Printed Circuit Board(PCB) Designing

[Arthi]

Dear All,
If you are into Electronics Field, and especially into Printed Circuit Board Designing, yes, you are the one whom am searching for to ask my doubts

1. What is the future for PCB Designing in InDIA.
2. Current s/w that have been used
3. Is there any Institutuon available to Learn PCB Designing(Preferably in Mumbai)
4. Does Orcad S/w has any value in the Market.

I want to update myself in this field.

Please help me friends

[Sanguine Sridhar]

:lol:

[Arthi]

:lol:

Why are you laughing here, I cann't understand.
I hope I have not cut any joke here to laugh like this. :evil:
If u cld help me, plz provide me the necessary information :) am seriouls. I have done many projects also.
ok Brother :)

[Shakthiprabha.]

:? :roll:

try google search arthi.

[Arthi]

:? :roll:

try google search arthi.

I tried Google search Guruji, If I find some one here i can ask all my doubts(I have been colleting date since last 2 years)

I cann't join full time course, some constraints am having...

Guruji, Oru vazhi kamikka kodadha?

[Arthi]

:? :roll:

try google search arthi.

I tried Google search Guruji, If I find some one here i can ask all my doubts(I have been colleting date since last 2 years)

I cann't join full time course, some constraints am having...

Guruji, Oru vazhi kamikka kodadha?

[Shakthiprabha.]

ARthi,

Enakku therinja solren.

u ask me questions referring me as guruji.

Half of the time I BLINK without knowing answers.

I am THE DUMBEST GURUJI ever a person can have :rotfl: :lol: :rotfl: :lol:

[kannannn]

Arthi, I can answer as much as I know. That's not my background but I have used the services of people who use these software for PCB design. Until as late as 4 months back, Orcad and PSpice were used extensively in India for PCB design. Top academic institutions in India also use these software for their projects. As for courses, I think IIT Mumbai must offer part time courses through their electronics dept. If you don't mind traveling to Bangalore, CEDT at IISc (www.cedt.iisc.ernet.in) regularly offers short term courses in electronics design, through the continuing education cell. Of course, there are plenty of private institutions too that offer these courses. The most famous in Bangalore seems to be the Indian Institute of Hardware Technology (IIHT, they call themselves) near Sankey Tank in Bangalore. But I can't vouch for the quality of private institutions.

[gaddeswarup]

A related question: Are there any good PCB manufacturers in India exporting to other countries?

[rajraj]

Arthi: Without knowing your educational/technical background it will be difficult for people to advise. In the US PCB design is taught in two year colleges or vocational schools attended by people who are looking for a job as a technician. You can get course material and a design kit from some institutes. Some people do it as a hobby for their own needs. Try searching for
'printed circuit board design course'. If you are degree holder this may not be for you unless you are planning to start your own company and want hands-on experience.

[rajraj]

A related question: Are there any good PCB manufacturers in India exporting to other countries?


Swarup,
Search using 'printed circuit board design India'. Looks like there are some exporters.

[gaddeswarup]

Arthi,
I think that there are some 'do it yourself' kind of instructions on the web. If you like, I can ask my wife (who knows a bit more about them) and send you the URLs.
Swarup

[Arthi]

swarup,

Please do it :), Thanx

[gaddeswarup]

Arthi,
Sent a PM.
swarup

[Arthi]

Arthi,
Sent a PM.
swarup

Thanks swarup for ur urls.
It gives me a feeling of understanding... :)

[Arthi]

Hi Friends, I have some doubts regarding PCB, Cld anyone help me :)

Some fundamental Questions in PCB Designing


1.what is Differential pair,length matching,How will u do placemnt ,and routing for Mixed(analog,Digital,RF) components.
2.what is DFM,DFA ?
3.what will be the pad size for 30 mil lead ?
4.What for we using Assembly,silk screen, mask ,paste layers. that's is purpose of those layer.
5.What do u mean by thermal?
6.what is series and parallel termination?How will u place the resistor of series and parallel termination.
7.What is layer Stackup?
8.To match the impedance what are all to be followed?

[raaja_rasigan]

Hi Friends, I have some doubts regarding PCB, Cld anyone help me :)

Some fundamental Questions in PCB Designing


1.what is Differential pair,length matching,How will u do placemnt ,and routing for Mixed(analog,Digital,RF) components.
2.what is DFM,DFA ?
3.what will be the pad size for 30 mil lead ?
4.What for we using Assembly,silk screen, mask ,paste layers. that's is purpose of those layer.
5.What do u mean by thermal?
6.what is series and parallel termination?How will u place the resistor of series and parallel termination.
7.What is layer Stackup?
8.To match the impedance what are all to be followed?

Arthi I can help u in this.... i working as a pcb design engineer in bangalore....

whatz ur educational background & what r u doing now reg. pcb

i'll come back to u in one or two days :D

[Anoushka]

why two threads for PCB? can we not merge them into one? :) info tends to be scattered if it is on two different threads!

[raaja_rasigan]

why two threads for PCB? can we not merge them into one? :) info tends to be scattered if it is on two different threads!

yeah...... the mods can delete the one which was created by me i.e., the other thread 8-)

[sarna_blr]

1.what is Differential pair?

The two signals which are equal in magnitude but having opposite polarity

Eg:- If one signal is Data plus, then other signal will be data minus

D+ and D- together form differential pair

2.How to route differencial pair?

Maintain two signals equal length and equal spacing through out the signals

[app_engine]

A few years back (2002-2003 time period), there were a number of active PCB exporters. One of them was extremely good - HiQ Hosur and we used to source boards having 6 / 8 layers with excellent quality for mfr of systems within India, and there used to be always priority issues for them w.r.t capacity allocating to us v/s exports. Then there was this stovec screens in Goa, Micropack in Jigani Indl estate Bangalore and Indal near Mysore (belongs to Indian Aluminium group, excellent facility that I've visited a few times).

I'm not sure how many of them are active today.

[app_engine]

>>2.what is DFM,DFA ? <<

I think these are related to manufacturability. (Designed for manufacture / Designed for Assembly). Simply means the design should cater to the needs of efficient assembly processes (like automatic component placement machines - onsertion / insertion etc.)

[app_engine]

>>4.What for we using Assembly,silk screen, mask ,paste layers. that's is purpose of those layer. <<

Again related to manufacturing.

"Mask" for the wire tracks is needed for automatic soldering machines to fill in the lead only on the pads. Without mask, it'll get applied everywhere making the assembly a mess:-)

At times, there are pads that need to be exposed (i.e. there should not be any mask) but should not be "soldered", for e.g. gold fingers / touch key pads etc. There is usually a separate "peelable mask" layer applied on top of them which can be peeled off after the wave soldering process.

[app_engine]

A typical technique used for multi-layered boards is to have a whole layer for Vcc and another whole layer for ground. While making the routing of signals in other layers much easier, this also helps in EMI considerations. Most digital systems that have 4 layer boards have these two as inner layers while the outer layers will have the other circuits.

[sarna_blr]

A typical technique used for multi-layered boards is to have a whole layer for Vcc and another whole layer for ground. While making the routing of signals in other layers much easier, this also helps in EMI considerations. Most digital systems that have 4 layer boards have these two as inner layers while the outer layers will have the other circuits.

kalakkunga :D

If u dont mind , innum konjam thelivaa solla try pannalaam :)

[Arthi]

:notworthy: sarna & app_engine for making this thread active :D


I have a very minimal knowledge abt PCB yet am interested to know about this field in detail.

Will join you people soon with my doubts

[Arthi]

I have designed multilayed PCB board(only 2 layers).

even designing 2 layered was a big task for me then :D

[app_engine]

2 layer board is not called "multi" layer board:-) It's usually referred as "double side" (and if it does have plated through holes for interconnections between the layers, it's called DSPTH)

Multilayer is > 2 layers:-) Usually, it's much simpler to design the 4 layer board than a 2 layer board for boards that use a CPU chip and the like, as the supply voltage & ground routing is not a big worry (being confined to the inner two layers). Only signals need to be routed in the external layers, making it all the much simpler. DSPTH is more complex, IMHO.

[app_engine]

>>If u dont mind , innum konjam thelivaa solla try pannalaam<<

sarna_blr, If you can eloborate on where I should be more clear, I can improve:-)

Do you mean the reference to Vcc? Well, I thought if someone is gonna venture into PCB design, it's not difficult to figure this out:-)

[Arthi]

yes,i just forgot the term double sided :x

can you expand the term DSPTH?

[app_engine]

Double Sided Plated Through Hole board. Here again, good designers tend to have in one layer all the tracks oriented in horizontal and vertical in another. (in other words, tracks in each layer are perpendicular, to the extent possible, to the other)

[Arthi]

>>If u dont mind , innum konjam thelivaa solla try pannalaam<<

sarna_blr, If you can eloborate on where I should be more clear, I can improve:-)

Do you mean the reference to Vcc? Well, I thought if someone is gonna venture into PCB design, it's not difficult to figure this out:-)

:redjump: :boo: :bluejump:

need to go a long way i know!!!

[app_engine]

Vcc is the +ve supply voltage to any digital circuit. The potential difference between the Vcc and the Ground makes it possible for these digital circuits to function. Few decades back there was all bipolar transistors that were used and (thus the term TTL, or transistor-transistor-logic) where typically 5V was the supply with less variance on upper / lower limits. Later most of them switched to complementary metal oxide semiconductor logic (CMOS, using field effect transistors) and supply voltages could go to more variations in the upper and lower limits than the conventional 5V.

And the binary logic of 1 & 0 is implemented like 5V is 1 and 0V (or ground) is 0. It could be vice versa also, depending upon the "truth table".

[raaja_rasigan]

neenda natkalaga kedappil podappattirundha en thurai sarndha thiri uyir petruvittadhe

[Arthi]

neenda natkalaga kedappil podappattirundha en thurai sarndha thiri uyir petruvittadhe

hey yes :redjump: welcome RR :D

please make your valuable presence here often & share your knowledge

[Arthi]

can i have freeware to bursh up my knowledge in PCB designing?

PS: I have knowledge in ORCAD, both in schematic & Layout & have expericence in designing a PCB board right from designing the circuit diagram in schematic & converting that to a PCB Design through Layout.

Tried up to double sided PCB board

[Arthi]

Hi Friends, I have some doubts regarding PCB, Cld anyone help me :)

Some fundamental Questions in PCB Designing


1.what is Differential pair,length matching,How will u do placemnt ,and routing for Mixed(analog,Digital,RF) components.
2.what is DFM,DFA ?
3.what will be the pad size for 30 mil lead ?
4.What for we using Assembly,silk screen, mask ,paste layers. that's is purpose of those layer.
5.What do u mean by thermal?
6.what is series and parallel termination?How will u place the resistor of series and parallel termination.
7.What is layer Stackup?
8.To match the impedance what are all to be followed?

Arthi I can help u in this.... i working as a pcb design engineer in bangalore....

whatz ur educational background & what r u doing now reg. pcb

i'll come back to u in one or two days :D

RR: for ur kind notice :D

[raaja_rasigan]

RR: for ur kind notice :D

:)

I know.... since no one is interested.... i left it as such..... now i cud c a couple of them posting in this & thought of participating in this

[raaja_rasigan]

can i have freeware to bursh up my knowledge in PCB designing?

PS: I have knowledge in ORCAD, both in schematic & Layout & have expericence in designing a PCB board right from designing the circuit diagram in schematic & converting that to a PCB Design through Layout.

Tried up to double sided PCB board

PCB designing involves both theoritical knowledge & practical working....... if you know Orcad, it is a kind of basic tool in this it is like a first step in practical study but now the company "cadence" has decided to stop Orcad.

Another shareware (some basic functions u can work it out / u can completely do a small layout) is PADS from Mentor Graphics

[Arthi]

:notthatway: I have very little knowledge in PCB designing field.

Busy with my stuff which earns me my bread & butter :P
will try to chipin :D

[Arthi]

Another shareware (some basic functions u can work it out / u can completely do a small layout) is PADS from Mentor Graphics

That's a great news for me RR :D

Will try to use this tool.
do u have url for this :roll: :D

[app_engine]

Well, though I haven't personally worked with pcad kind of tools for PCB design, I've "lived" with PCBs for more than a decade as part of the team:-) One of my most dreaded "smells" in life is that of a burnt track on a pcb:-) We used to call this "electronic smell":-))

[Arthi]

I am very much happy that this thread is activated again.

I request you all add value to this thread :D

[Arthi]

Well, though I haven't personally worked with pcad kind of tools for PCB design, I've "lived" with PCBs for more than a decade as part of the team:-) One of my most dreaded "smells" in life is that of a burnt track on a pcb:-) We used to call this "electronic smell":-))

it happened with me too... though my experience in this field is very less but had great/high experience in burning track :wink: :oops:

[raaja_rasigan]

I never used to be at a manufacturing / assembly house....... we / I will be doing in sofware & sending the gerbers (hope u all know what it is...... if i use any technical terms).. just saw some fabricated board

[Arthi]

RR: am the only novice here, ironically who started this thread :lol:

i heard of the name gerbers :roll:

cld u plz explain me?

[raaja_rasigan]

http://www.mentor.com/products/pcb/pads/pads_eval.cfm

try this for pcb software

[app_engine]

As most are aware, PCB pattern routing is both an art and engineering as it's not simply connecting from one circuit point to another. Improper routing of patterns, apart from making it appear shabby and contributing to inefficient manufacturing processes, can also cause great troubles in the functionality / reliability of the unit.

Let me share an experience as to how much the routing of patterns in PCB is so important, without getting into the actual case (as the information is proprietory). This was a case of replacing an expensive IC with an equivalent from a competitor with exactly same functionality / quality / reliability / # of pins etc but only with a different pin configuration. In addition, the requirement was to have provision to mount either of them (i.e. from either source - expensive and economical) on the board, as availability for production is another consideration.

Well, the board got redesigned / tested fine during all the lab / factory / beta validations, with both chips and all combinations. Then we shipped a bunch of units to field and had the worst nightmare for that product. (I had to personally spend a lot of time in customers' places, travelling through out the country etc. along with the field engineers, to carry out the fix). The routing of patterns was the cause of some inexplicable spikes for some line driver chips on the board that used to fail like "eesal" and considerable time and money was spent to include additional protection on 100's of boards and the amount of customer yelling that the field technicians had to undergo was phenomenal.

Bottomline: PCB pattern routing is more electronic engineering than drawing / art.

[Arthi]

http://www.mentor.com/products/pcb/pads/pads_eval.cfm

try this for pcb software

Downloading the s/w :D

[raaja_rasigan]

http://www.mentor.com/products/pcb/pads/pads_eval.cfm

try this for pcb software

Downloading the s/w :D

i haven't tried downloading, but size shud be huge

[Arthi]

yes it is huge :(

Trying it letz see :D

[raaja_rasigan]

Bottomline: PCB pattern routing is more electronic engineering than drawing / art.

:yes:

first preference for electrical correctness then art.

For example, we need to give enough space between 2 tracks to avoid electrical/magnetic coupling between the traces. But for a differential pair, u cannot have more space than the specified ones.

[raaja_rasigan]

RR: am the only novice here, ironically who started this thread :lol:

i heard of the name gerbers :roll:

cld u plz explain me?

Gerber files are the output files which we need to send to the manufacturers for getting our finished PCB.

As i told already, I can give just a hint about the terms, while reading some documents & practically doing a board we will be know a lot of things.

[Arthi]

Bottomline: PCB pattern routing is more electronic engineering than drawing / art.

:yes:

first preference for electrical correctness then art.

For example, we need to give enough space between 2 tracks to avoid electrical/magnetic coupling between the traces. But for a differential pair, u cannot have more space than the specified ones.

Yes i too agree...
when we were in college... we used to design a layout by keeping pads close to each other. we used to give importance too look and alingment of teh compones and while place the componed and soldering...we used to encounter all the problems

[Arthi]

RR: am the only novice here, ironically who started this thread :lol:

i heard of the name gerbers :roll:

cld u plz explain me?

Gerber files are the output files which we need to send to the manufacturers for getting our finished PCB.

As i told already, I can give just a hint about the terms, while reading some documents & practically doing a board we will be know a lot of things.

yes i am getting it. I had gone to PCB desining shop with my own PCB design printouts

[raaja_rasigan]

innaikku class podhum.... nalla padichuttu nalaikku vanga... test vekkiraen :) :lol:

[Arthi]

yes sir :)

still downloading the s/w 53% reached

on the serious note:
i am ready to take up assignment too if u ppl have time, i don't mind doing :)

PCB designing is my passion, but as of now no knowledge in it :(

[raaja_rasigan]

on the serious note:
i am ready to take up assignment too if u ppl have time, i don't mind doing :)
ready to guide u if time persmits... so that i cud also learn by teaching some one



PCB designing is my passion, but as of now no knowledge in it :(

it its is just a hobby, then i donno how long u will be interested in it

[Arthi]

hey it has been my hobby for last 5 years :D
if everything materialise as per my plan :redjump: then ...

u don't worry, i keep the momentum :D

[raaja_rasigan]

Good Night (guessing u r in India / location shows Mumbai)

[Arthi]

Good Night (guessing u r in India / location shows Mumbai)

yes am

ok gudnite :D

[Arthi]

:redjump: :boo: :bluejump:

RR: I installed the s/w successfully.
From tomorrow onwards will start practising :D

[sarna_blr]

>>If u dont mind , innum konjam thelivaa solla try pannalaam<<

sarna_blr, If you can eloborate on where I should be more clear, I can improve:-)

Do you mean the reference to Vcc? Well, I thought if someone is gonna venture into PCB design, it's not difficult to figure this out:-)

Unga answer'la irundhe varane

>>2.what is DFM,DFA ? <<

I think these are related to manufacturability. (Designed for manufacture / Designed for Assembly). Simply means the design should cater to the needs of efficient assembly processes (like automatic component placement machines - onsertion / insertion etc.)

DFM--design for manufacturing(valid point dhaan)
Ippa Hi-Q hosur Fab house'a eduththukkitteengana,
1- min trace width 4 mil
They can manufacture minimum 4 mil trace and 4 mil spacing.
Ippa naama 4 mil trace'a vida kammiya trace width eduththukkittom'na---we have to look for another fab house---IMO Hi-Q is one of the best in South India--I dont know anyother fabhouse in India will fab a board less than 4 mil trace width

IMO--FAB=Manufacturiong(notes)

2- Maximum 16 layers
Coming to number of layers--Ennoda arivukku ettiya varayil--In India we can FAB upto 16 layers.
So we should not go behind 16 layers ---if we are going to fab/manufacture in India

Idhu maadhiri innu konjam detailed'a sollalaam--innum neraya sollaalaam...,

Now Let us come to DFA
DFA-Design for assemly

Let me put here my persnal experience( Costly lesson)
In my company, we designed a board
Size--12x10 inch
layer count-- 16 layers

While testing (in house testng), we faced a problem. Wn plugging and un-plugging test bus connectors--board used to get bend--So we planned to go for higher thinkness.
There we made a big mistake of taking 3.2 mm board thickness
We ordered 10 boards--(cost 6 lakhs)
Wn the board came we were not able to solder even a single through-hole component--because the board thickness is 3.2 mm and the pin length is less than 3.2 mm---wt to do--we lost 6 lakhs

This is nothing but DFA--ie Design for Assemly

Idhu madhiri konjam detailed'aa sonneengana nalla irukkum

[raaja_rasigan]

sarna..... useful details...... keep it up

[raaja_rasigan]

:redjump: :boo: :bluejump:

RR: I installed the s/w successfully.
From tomorrow onwards will start practising :D

Arthi, u can use the Help to get started with the basics & there will be a sample layout provied as a tutorial......

Happy layouting

[sarna_blr]

:redjump: :boo: :bluejump:

RR: I installed the s/w successfully.
From tomorrow onwards will start practising :D

Arthi, u can use the Help to get started with the basics & there will be a sample layout provied as a tutorial......

Happy layouting

Hi R_R,
neenga endha tool use pannureenga

[raaja_rasigan]

PADS-dhan maximum use panraen

But I know to work in,

Allegro

& other tools like

Orcad
AutoCAD

[sarna_blr]

PADS-dhan maximum use panraen

But I know to work in,

Allegro

& other tools like

Orcad
AutoCAD

PADS great

[sarna_blr]

RR: am the only novice here, ironically who started this thread :lol:

i heard of the name gerbers :roll:

cld u plz explain me?

Gerber is similar to NEGATIVE(in photographs)

If we have NEGATIVE, we can develop the photo----
In similar way --if we have gerber we can manufacture/fab the board
In another way of explaination,
If we designed 2 layer board,double side components
It will have
1...top routing layer---(will have pins, traces , via )
2...bottom routing layer---(will have pins, traces , via )
3...Top silkscreen---(will have component names which are placed on top side)
4...bottom silkscreen---(will have component names which are placed on bottom side)
5...top solder mask---(will have a mask other than the solderable area of top side)
6...bottom solder mask---(will have a mask other than the solderable area of bottom side)
7...Drill legend----(will have the drilling informations)

The mirror image of above said things (or) artwork of above said things (or) the drawing files in gerber format(those can be viewed in gerber viewer) is called as gerbers

[sarna_blr]

yaaraavudhu vandhu--interact pannungapa

[raaja_rasigan]

yaaraavudhu vandhu--interact pannungapa

8 hrs work panna kanakku kamikkanum anne :P

[sarna_blr]

yaaraavudhu vandhu--interact pannungapa

8 hrs work panna kanakku kamikkanum anne :P

Eight hours work pannina kanakku kaamikkanumaa?
illa 8 hours office'la irundhu kanakku kaattanumaa?

Enga office work irundhaa pannu---illanaa 9 hours office'la kundhinu keda... :(

[sarna_blr]

As most are aware, PCB pattern routing is both an art and engineering as it's not simply connecting from one circuit point to another. Improper routing of patterns, apart from making it appear shabby and contributing to inefficient manufacturing processes, can also cause great troubles in the functionality / reliability of the unit.

Let me share an experience as to how much the routing of patterns in PCB is so important, without getting into the actual case (as the information is proprietory). This was a case of replacing an expensive IC with an equivalent from a competitor with exactly same functionality / quality / reliability / # of pins etc but only with a different pin configuration. In addition, the requirement was to have provision to mount either of them (i.e. from either source - expensive and economical) on the board, as availability for production is another consideration.

Well, the board got redesigned / tested fine during all the lab / factory / beta validations, with both chips and all combinations. Then we shipped a bunch of units to field and had the worst nightmare for that product. (I had to personally spend a lot of time in customers' places, travelling through out the country etc. along with the field engineers, to carry out the fix). The routing of patterns was the cause of some inexplicable spikes for some line driver chips on the board that used to fail like "eesal" and considerable time and money was spent to include additional protection on 100's of boards and the amount of customer yelling that the field technicians had to undergo was phenomenal.

Bottomline: PCB pattern routing is more electronic engineering than drawing / art.

Unga english konja high level'aa irukku, adhanaala purinjukkuradhukku kashttamaa irukku... please reconsider it....

[sarna_blr]

Hi Friends, I have some doubts regarding PCB, Cld anyone help me :)

Some fundamental Questions in PCB Designing


1.what is Differential pair,length matching,How will u do placemnt ,and routing for Mixed(analog,Digital,RF) components.
2.what is DFM,DFA ?
3.what will be the pad size for 30 mil lead ?
4.What for we using Assembly,silk screen, mask ,paste layers. that's is purpose of those layer.
5.What do u mean by thermal?
6.what is series and parallel termination?How will u place the resistor of series and parallel termination.
7.What is layer Stackup?
8.To match the impedance what are all to be followed?

For ur 1st question I have not answered fully--I will answer u later---Because u should know the basics first--ok

For ur second question answered upto my knowledge

Now ur 3rd question,...3.what will be the pad size for 30 mil lead ?

If lead is 30 mil dia, then the hole required to insert the pad should be more than 30 mil ---Am i right?
If u give 30 mill drill size, then the fabricator will come with 26 mil drilled hole---Because he requires minmum 4 mil for finishing...
Finishing means---After drilling he will coat the drilled area with copper for getting proper connectivity in all layers---So he require 4 mills extra---
So now 30+ 4= 34
If u give 34mil as hole size for fabricator--he will give you 30 mil drilled hole--But if it is exactly 30 mils hole size means, while inserting the lead, u will have problem---so u can increase another 2 to 4 mils

So up to my knowledge for 30 mil lead, u have to provide 36 to 38 as drill size
36 is minimum requirement

Addition to that 12 to 15 mil annular ring is required
Annular ring is nothing but Total pad size minus Drill
So total pad size is Annula ring plus drill size

So 15 + 36=51
For 30 mil lead 51 mil pad is required and 36 mil drill size is required
Got my point,
Addition to that +5 mil solder mask is required

[Arthi]

:redjump: :boo: :bluejump:

RR: I installed the s/w successfully.
From tomorrow onwards will start practising :D

Arthi, u can use the Help to get started with the basics & there will be a sample layout provied as a tutorial......

Happy layouting

Yesterday i had a glance about the schematic part it would be more like ORCAD i feel :roll:

I am happy to know that you work on PADS which i am going to explore :D

this thread is getting activated really :thumbsup:

[Arthi]

hi sarna, RR, app_engine

I request you all to share your knowledge here and often visit this thread.

I know that I will definetly ask silly questions, before asking any question i will first go through the help file from the PADS software as suggested by RR :D

thanks all once again for your valuable participation, I really am getting motivated and hope will grasp the concept fast without troubling you friends much

[raaja_rasigan]

Yesterday i had a glance about the schematic part it would be more like ORCAD i feel :roll:


every tool has the basic concept with different working methods & terms... since u have knowledge in ORCAD, u can learn easily this PADS Logic (schematic tool in PADS)

[app_engine]

sarna_blr,

Excellent postings! அருமையா எழுதுறீங்க. தொடருங்கள்!

About my posting having complex language, I'm sorry. Since this thread is of technical nature (and I assume mostly read by engineers related to electronics), I thought a little indulgence in technical terms is not out of place. I'll try to explain as detailed and simple as possible, in any future posts. Thank you!

[app_engine]

An additional info on the "hole size" to what sarna_blr has posted.

What if the whole size is too large? That is, for example, if the size of the component lead (or pin) is 30 mil and you have a 42 mil hole? Can't it be mounted and soldered? Yes it can, but with atleast two big problems, when automatic soldering is done:

1. Improper soldering / trapping of air in the soldering joint possibly leading to "dry-solder" which means no connectivity between the pin and the hole / pad

2. "Escape" of solder (leak thru the gap) from the molten bath into the "other" side of the PCB (i.e. to the component side, which is not touching the molten solder) as small "balls" that could go and get stuck in unwanted places, causing short-circuits (unwanted connections).

So appropriate hole size that fits the component lead (should be possible to comfortably insert while not too loose) is important.

[Arthi]

In PADS what is Modeless Command?
How to use it?

[Arthi]

RR:
I just started going through the help file

I am familiar with the mouse actions :P

[Arthi]

What is Bug Media Wizard?

[raaja_rasigan]

In PADS what is Modeless Command?
How to use it?

Modeless command: this is the name given for invoking a command thru keyboard (i.e, using a combination of keys)

1) For eg: u need to identify the location of a capacitor C1...... instead of zooming & searching area by area in a dense board, u can simply use a modeless command (type) "ss C1" (at this point of time u shud have selected the pointer button in the toolbar)

the command is ss ref des

2) another example: to point to a location for eg: to place the cursor over board origin ie. (0,0).... use the command ss 0 0

help tutorial will give u some more examples which u will be frequently using while doing a layout

[raaja_rasigan]

An additional info on the "hole size" to what sarna_blr has posted.



App_engine, really useful post for me... :clap:

sarna..... good post

After cing some detailed posts from u 2, i thought of asking some of my doubts:

1) Can some one explain the concept of EMI & EMC & its effects with a practical example

(1 1/2 month back i attended an interview, there they asked me the same question & i need to explain this for a mobile phone, my answer is :? & :roll: )

//whenever i get some doubt i'll post it immediately//

[Arthi]

In PADS what is Modeless Command?
How to use it?

Modeless command: this is the name given for invoking a command thru keyboard (i.e, using a combination of keys)

1) For eg: u need to identify the location of a capacitor C1...... instead of zooming & searching area by area in a dense board, u can simply use a modeless command (type) "ss C1" (at this point of time u shud have selected the pointer button in the toolbar)

the command is ss ref des

2) another example: to point to a location for eg: to place the cursor over board origin ie. (0,0).... use the command ss 0 0

help tutorial will give u some more examples which u will be frequently using while doing a layout

RR: Morning :)
Thanks for the explanation, I will try this out at home and ask you if i face any problem :P

I got the below link which is also useful and it talks about modeless command

If any novice like me visit this thread, it will be useful :D

http://www.people.vcu.edu/~rhklenke/tutorials/PADS/PADS_Tutorial_User_Interface/UserInterface.html

[raaja_rasigan]

RR:
I just started going through the help file

I am familiar with the mouse actions :P

start with that simple layout given in tutorial..... if needed i'll review it once u finish that...

about Bug media wizard.... haven't yet came across that word.... i'll try to find it if it is related to PADS :)

[Arthi]

RR:
I just started going through the help file

I am familiar with the mouse actions :P

start with that simple layout given in tutorial..... if needed i'll review it once u finish that...

about Bug media wizard.... haven't yet came across that word.... i'll try to find it if it is related to PADS :)

Will do it sure, and please review it.

As of now i am just picking up the component from the library trying placing the components :roll:

Today will try to design a circuit after aapis hrs :P

[raaja_rasigan]

RR: Morning :)


Good mornign Arthi..... :)

let me start my official work :(

[sarna_blr]

RR: Morning :)


Good mornign Arthi..... :)

let me start my official work :(

Good morning for everybody,

Hi R_R,
From today onwards--i too will busy on my official work----
but i will be in keeping touch with this forum...

[sarna_blr]

sarna_blr,

Excellent postings! அருமையா எழுதுறீங்க. தொடருங்கள்!

About my posting having complex language, I'm sorry. Since this thread is of technical nature (and I assume mostly read by engineers related to electronics), I thought a little indulgence in technical terms is not out of place. I'll try to explain as detailed and simple as possible, in any future posts. Thank you!

Romba Thanks,

But I am very much poor in English language---Like me many of friends who studied in Tamil nadu are poor in English comminucation skill----So let our language be very simple here...,

I think most of the Forum members will be tamilians---so tamizh'la pesuna problem illainu nenakkurane....

[sarna_blr]

An additional info on the "hole size" to what sarna_blr has posted.



App_engine, really useful post for me... :clap:

sarna..... good post

After cing some detailed posts from u 2, i thought of asking some of my doubts:

1) Can some one explain the concept of EMI & EMC & its effects with a practical example
(1 1/2 month back i attended an interview, there they asked me the same question & i need to explain this for a mobile phone, my answer is :? & :roll: )

//whenever i get some doubt i'll post it immediately//


EMI & EMC
Its a big topic---
Let me give introduction about these things based on my practical knowledge---

EMI is nothing but Electromagnetic Interference...,,,

Cross talk, Impedance mismatch, noise, and so many things will come under EMI

EMC is Electromagnetic compatibility---is a process of avoiding EMI effectively

Simple to say like this---But there are lot of things to discuss about EMI---I will continue for the best of my knowledge...

[Arthi]

sarna_blr,

Excellent postings! அருமையா எழுதுறீங்க. தொடருங்கள்!

About my posting having complex language, I'm sorry. Since this thread is of technical nature (and I assume mostly read by engineers related to electronics), I thought a little indulgence in technical terms is not out of place. I'll try to explain as detailed and simple as possible, in any future posts. Thank you!

Romba Thanks,

But I am very much poor in English language---Like me many of friends who studied in Tamil nadu are poor in English comminucation skill----So let our language be very simple here...,

I think most of the Forum members will be tamilians---so tamizh'la pesuna problem illainu nenakkurane....

No proba sarna, edhula PEsurOmgaradhu mukkiyam illa, sOnna samaacharam purindhudha garadhu dhaan mukiyum

as far as we are comfortable & able to understand, lang will not be a problem :D

[sarna_blr]

An additional info on the "hole size" to what sarna_blr has posted.

What if the whole size is too large? That is, for example, if the size of the component lead (or pin) is 30 mil and you have a 42 mil hole? Can't it be mounted and soldered? Yes it can, but with atleast two big problems, when automatic soldering is done:

1. Improper soldering / trapping of air in the soldering joint possibly leading to "dry-solder" which means no connectivity between the pin and the hole / pad

2. "Escape" of solder (leak thru the gap) from the molten bath into the "other" side of the PCB (i.e. to the component side, which is not touching the molten solder) as small "balls" that could go and get stuck in unwanted places, causing short-circuits (unwanted connections).

So appropriate hole size that fits the component lead (should be possible to comfortably insert while not too loose) is important.

Thanks nanbaaa............

[Arthi]

An additional info on the "hole size" to what sarna_blr has posted.

What if the whole size is too large? That is, for example, if the size of the component lead (or pin) is 30 mil and you have a 42 mil hole? Can't it be mounted and soldered? Yes it can, but with atleast two big problems, when automatic soldering is done:

1. Improper soldering / trapping of air in the soldering joint possibly leading to "dry-solder" which means no connectivity between the pin and the hole / pad

2. "Escape" of solder (leak thru the gap) from the molten bath into the "other" side of the PCB (i.e. to the component side, which is not touching the molten solder) as small "balls" that could go and get stuck in unwanted places, causing short-circuits (unwanted connections).

So appropriate hole size that fits the component lead (should be possible to comfortably insert while not too loose) is important.


When we first designed our PCB board, we faced all these problems.
While designing the Layout, the pad size were looking too big and we thought the size would be perfect enough to solder the components
But in practical, after getting the board on hand the thing changed upside down :x

[sarna_blr]

[tscii:06ec1a9def]So now about CrossTalk( one of the factors of EMI)

I copied from an article....,,

Crosstalk: When two traces are placed close
together, the current flowing down one (in this context
we call it the “aggressor” trace) induces a current
in the other (victim) trace. The electric field
causes a current in the victim trace that flows both
ways, backwards and forwards. Think of the case of
a single electron at a point along the aggressor
trace. It will tend to repel electrons in the victim
trace in both directions away from that point. We
often call this type of coupling “capacitive” coupling.
The aggressor trace also generates a magnetic
field, which in turn generates a current in the reverse,
or backward direction in the victim trace. We
often call this type of coupling “inductive” coupling.
These two types of coupling tend to reinforce
each other in the backwards direction, but they tend
to cancel each other in the forward direction (they
exactly cancel in stripline environments.) Hence,
reverse coupling, or backwards crosstalk, tends to
be the problem in this situation.
In summary, crosstalk is a direct result of the
electromagnetic field radiated from the aggressor
trace

Innum neraya sollalaaam........,[/tscii:06ec1a9def]

Innum simple'aa sollanum'na,

2 engg's pakkaththu pakkaththula ukkaandhukkittu, oruththaroda velaya innoruththar seiyya vidaama thadukkuradhukku peru dhaan----

[raaja_rasigan]

Good morning for everybody,

Hi R_R,
From today onwards--i too will busy on my official work----
but i will be in keeping touch with this forum...

good morning sarna... i guess only 4 of us are part of this thread... let us keep it active as long as possible....

though we can learn a pdf doc for any doubts.... reading in this forum gets into mind easily like chatting with friends.. so lets continue with our tech discussions.... though a minimum amount of digressions are acceptable like good morning, how r u etc. :D

[Arthi]

I am here to keep this thread active :roll:
you 3 bear answering my silly questions :P

[sarna_blr]

Good morning for everybody,

Hi R_R,
From today onwards--i too will busy on my official work----
but i will be in keeping touch with this forum...

good morning sarna... i guess only 4 of us are part of this thread... let us keep it active as long as possible....

though we can learn a pdf doc for any doubts.... reading in this forum gets into mind easily like chatting with friends.. so lets continue with our tech discussions.... though a minimum amount of digressions are acceptable like good morning, how r u etc. :D

Is there any possible of uploading PDF documents here---so that any one can download it and access

[sarna_blr]

I am here to keep this thread active :roll:
you 3 bear answering my silly questions :P

never degrade about yourself---

No-one is genius in world--everybody is learner---

u may be in LKG---

I may be in 1st standard---

Our R_R and App_engine may be in SSLC---

thatsall

[Arthi]

As of now only we four are contributing/learning from this thread.

Why don't you share with four of us, if u have no problem? :idea:

anyone joins this thread,we can circulate the pdf :idea:

[sarna_blr]

As of now only we four are contributing/learning from this thread.

Why don't you share with four of us, if u have no problem? :idea:

anyone joins this thread,we can circulate the pdf :idea:

How come?

Ho to upload PDF documents in this thread?

[Arthi]

sarna, rightly said...

I will improve my PCB knowledge, btw i can improce my electronics knowledge too, ofcouse which is essential.

again i get a chance to brush up my knowledge after 4 years... i am not currently into electronics field... that is why i made such statement.

[sarna_blr]

sarna, rightly said...

I will improve my PCB knowledge, btw i can improce my electronics knowledge too, ofcouse which is essential.

again i get a chance to brush up my knowledge after 4 years... i am not currently into electronics field... that is why i made such statement.

To improve PCB knowledge--Electronics knowledge is very important

[raaja_rasigan]

To improve PCB knowledge--Electronics knowledge is very important

PCB is nothing but an electronics circuit's hardware

[sarna_blr]

To improve PCB knowledge--Electronics knowledge is very important

PCB is nothing but an electronics circuit's hardware

naan Printed Circuit Board'nla nenachEn :lol: :lol: :lol:

Veettu velai theriyum'nu sonna--samayalum theriyum'nu arththam

Samayal theriyum'nu sonnaa, veettu velayum theriyum'nu arththamaa?

Samayal ---PCB
Veettu velai---Electronics

[app_engine]

When there was this limitation of fabricating only DSPTH and not more layers in the country (I'm talking about many years back), the EMI problem was quite sharp (though that has come down after easy availability of 4 layer boards inside the country, with the supply and ground layers taking away a lot of pressure on the PCB designer).

Otherwise, on just a double side board, it was challenge for all the clock signals (remember we're talking only about 2 Mhz:-) With frequencies in the order of GHz, I expect this to be phenomenal nowadays (microwaves work in this freq range, cooking food - though at higher power / intensity)

OK, coming to the topic, one of the techniques used to avoid this clock signal (like the PCM clock) getting distorted was to give a "ground guard". i.e. if there is a long running track of clock signal, have a "ground loop track" around the "clock track" !

[sarna_blr]

Inru crosstalk'a paththi chinnadhaa oru bit

Crosstalk, which is the coupling of energy from one line to another, will occur whenever the
electromagnetic fields from different structures interact. In digital designs the occurrence of
crosstalk is very widespread. Crosstalk will occur on the chip, on the PCB board, on the
connectors, on the chip package, and on the connector cables. Furthermore, as technology
and consumer demands push for physically smaller and faster products, the amount of
crosstalk in digital systems is increasing dramatically. Subsequently, crosstalk will introduce
significant hurdles into system design, and it is vital that the engineer learn the mechanisms
that cause crosstalk and the design methodologies to compensate for it.

[raaja_rasigan]

Today a practical doubt (happened today in the board of my collegue):

Pin sequences for the power connector & a RJ45 is reversed in foot print.

Board is manufactured & while assembling they found the problem.

What will they do to make the board work or is the board is a waste?

// customer mailed saying that he need to do some surgery in the board //

[app_engine]

oh..Oh:-(

Power connector may be possible to cut / re-route the tracks (can manually drill an extra hole and wire). Though the same may be done for RJ45, it would be a lot more messier. They may instead think about buying RJ45's with wires (not PCB mounting type) and mount them on the plastic box itself or on a bracket...

Ofcourse the above suggestions are only if the board is too expensive and time for revised board to obtain is too long etc. Otherwise, personally, I never liked the cut-and-route kind of works on PCB, though we had done a lot of them those days.

[app_engine]

I am here to keep this thread active :roll:
you 3 bear answering my silly questions :P

never degrade about yourself---

No-one is genius in world--everybody is learner---

u may be in LKG---

I may be in 1st standard---

Our R_R and App_engine may be in SSLC---

thatsall

Actually, I am an "illiterate" in PCB design (means no formal education). Though worked with them for many years as "thaRkuRi", now practically "retired":-)) For the last 5 years or so probably didn't even touch a PCB (as I've got into ERP implementations / software analysis / design / development etc on a full-time basis).

So any information that I post here may be "dated" (means very old). However, I feel some of these are basic in nature and can serve as primers to aspiring PCB designers.

[Arthi]

Hey I faced an error message while closing the PADS s/w (schematic)

Yesterday while designing a Circut, i placed 3 powersupplies and deleted the rest of the 2 power supplies. I was naming the sheet by providing some information like company name, sheet name etc.
After this changes i save the design. I made a few changes though minor in the design and I tried to close the design, I came across with a dialog box "Do you want to save changes". I opted for 'Yes" option. After this I came across an error message "Segmentation Fault ..."

What does it mean?

[Arthi]

Today a practical doubt (happened today in the board of my collegue):

Pin sequences for the power connector & a RJ45 is reversed in foot print.

Board is manufactured & while assembling they found the problem.

What will they do to make the board work or is the board is a waste?

// customer mailed saying that he need to do some surgery in the board //

I am not an expert (obviously) to suggest you any tips but we too came across such issues

To avoid this problem, we should always take printout of the mirror image of the layout.
shouldn't we?

[Arthi]

For the last 5 years or so probably didn't even touch a PCB (as I've got into ERP implementations / software analysis / design / development etc on a full-time basis).


same goes good for me too, but my hunger to become a good PCB designer oneday yields me the result !!!

[sarna_blr]

Today a practical doubt (happened today in the board of my collegue):

Pin sequences for the power connector & a RJ45 is reversed in foot print.

Board is manufactured & while assembling they found the problem.

What will they do to make the board work or is the board is a waste?

// customer mailed saying that he need to do some surgery in the board //

If those board are used for only testing purpose, then u can mount the components on bottom side(if all through hole)----
try it.....

[raaja_rasigan]

The pin sequence is not our problem... the datasheets doesn't show the pin#1 marking & my collegue has mailed about this while releasing the gerbers

: anyway thanks for ur suggestions sarna & app, since my practical knowledge is very minimal i thought of asking this

[sarna_blr]

The pin sequence is not our problem... the datasheets doesn't show the pin#1 marking & my collegue has mailed about this while releasing the gerbers

: anyway thanks for ur suggestions sarna & app, since my practical knowledge is very minimal i thought of asking this

Whether ur problem get solved---if not

Please give me details--i think I can help you

[raaja_rasigan]

Arthi, reg: ur error message, i am not using schematic much, though I know the basics in schematic .... search with help & check.

Mostly customers send us the netlist, so that we directly work in Layout.

Also, mostly schematic is done in orcad capture

[Arthi]

Arthi, reg: ur error message, i am not using schematic much, though I know the basics in schematic .... search with help & check.

Mostly customers send us the netlist, so that we directly work in Layout.

Also, mostly schematic is done in orcad capture

ok no probs :D

so you do only layout in PADS?

[raaja_rasigan]

The pin sequence is not our problem... the datasheets doesn't show the pin#1 marking & my collegue has mailed about this while releasing the gerbers

: anyway thanks for ur suggestions sarna & app, since my practical knowledge is very minimal i thought of asking this

Whether ur problem get solved---if not

Please give me details--i think I can help you

He is a US customer & manufactured in US.... so they won't get bck to us for any manufacturing suggestions

[raaja_rasigan]

Arthi, reg: ur error message, i am not using schematic much, though I know the basics in schematic .... search with help & check.

Mostly customers send us the netlist, so that we directly work in Layout.

Also, mostly schematic is done in orcad capture

ok no probs :D

so you do only layout in PADS?

I can say that i frequently work in Layout

[sarna_blr]

The pin sequence is not our problem... the datasheets doesn't show the pin#1 marking & my collegue has mailed about this while releasing the gerbers

: anyway thanks for ur suggestions sarna & app, since my practical knowledge is very minimal i thought of asking this

Whether ur problem get solved---if not

Please give me details--i think I can help you

He is a US customer & manufactured in US.... so they won't get bck to us for any manufacturing suggestions

Actualla unga question idhu dhaana,
Pin sequences for the power connector & a RJ45 is reversed in foot print. Board is manufactured & while assembling they found the problem.

If so u can mount the component on bottom side(surely if through hole)

Ore velai unga question idhu illana--neenga konjam thelivaa kelvi kekkalaam...

By the by I am having little lot of practical experience--because In my company, we will design, manufacture, assemble and test---so like this problem we have faced a lot...
So i think I can help u

[raaja_rasigan]

Actualla unga question idhu dhaana,
Pin sequences for the power connector & a RJ45 is reversed in foot print. Board is manufactured & while assembling they found the problem.

If so u can mount the component on bottom side(surely if through hole)

Yes..... this is my question & in the bottom side of the board.. a daughter card is to be attached.. so i don't thing they can mount in the opposite side

sarna... r u doing circuit designing also..... if so how can i start learning this.... i am zero in this part & mostly companies calling for Board designing / Hardware... so i feel a bit tough to shift

[sarna_blr]

Actualla unga question idhu dhaana,
Pin sequences for the power connector & a RJ45 is reversed in foot print. Board is manufactured & while assembling they found the problem.

If so u can mount the component on bottom side(surely if through hole)

Yes..... this is my question & in the bottom side of the board.. a daughter card is to be attached.. so i don't thing they can mount in the opposite side

sarna... r u doing circuit designing also..... if so how can i start learning this.... i am zero in this part & mostly companies calling for Board designing / Hardware... so i feel a bit tough to shift

Best IDEA---u should join a company saying that u have basic knowledge in it----
Circuit designing is not a big deal----But i am learning now---
Upto my knowledge,
u should know the basics of electronics to learn circuit designing and if PCB knowledge--it will be very helpful for u

[raaja_rasigan]

OK..... first i'll thorough my Electronics basics

[sarna_blr]

OK..... first i'll thorough my Electronics basics

:D :D

[Arthi]

Circuit designing.... are u ppl talking abt schematic??? in ORCAD it is called capture

[sarna_blr]

Circuit designing.... are u ppl talking abt schematic??? in ORCAD it is called capture

Not about Schematic editing---Schematic designing..... :)

[Arthi]

What is the difference between schematic designing & Editing?

[sarna_blr]

What is the difference between schematic designing & Editing?

Designin means---They will tell u that they need this function--for that u have select appropriate components and design the schematic

Editing means--they will give u the designed schematic and u have to capture it in ORCAD CAPTURE or someother tool

got it

[Arthi]

What is the difference between schematic designing & Editing?

Designin means---They will tell u that they need this function--for that u have select appropriate components and design the schematic

Editing means--they will give u the designed schematic and u have to capture it in ORCAD CAPTURE or someother tool

got it

ok ok got it :)

designing is tougher :roll:
Do you design a circuit :shock: :clap:
Let me learn one by one

Thanks sarna for ur explanation :D

[sarna_blr]

What is the difference between schematic designing & Editing?

Designin means---They will tell u that they need this function--for that u have select appropriate components and design the schematic

Editing means--they will give u the designed schematic and u have to capture it in ORCAD CAPTURE or someother tool

got it

ok ok got it :)

designing is tougher :roll:
Do you design a circuit :shock: :clap:
Let me learn one by one

Thanks sarna for ur explanation :D

I am learning now.....,

[raaja_rasigan]

What is the difference between schematic designing & Editing?

Designin means---They will tell u that they need this function--for that u have select appropriate components and design the schematic

Editing means--they will give u the designed schematic and u have to capture it in ORCAD CAPTURE or someother tool

got it

ok ok got it :)

designing is tougher :roll:
Do you design a circuit :shock: :clap:
Let me learn one by one

Thanks sarna for ur explanation :D

I am learning now.....,

if any link for step by step learning, provide it.. i'll try

[sarna_blr]

What is the difference between schematic designing & Editing?

Designin means---They will tell u that they need this function--for that u have select appropriate components and design the schematic

Editing means--they will give u the designed schematic and u have to capture it in ORCAD CAPTURE or someother tool

got it

ok ok got it :)

designing is tougher :roll:
Do you design a circuit :shock: :clap:
Let me learn one by one

Thanks sarna for ur explanation :D

I am learning now.....,

if any link for step by step learning, provide it.. i'll try

I have no links---But i will give u tips

[Arthi]

Hey we can share the knowledge about designing circuits, so everyone will be benifited.

I don't have even my Basic of Electronics book on hand :(

[app_engine]

While you people are getting into circuit design (& schematic drawing), let me throw in some more info (probably "dated") on PCB laminates.

We've had an earlier posting on the "board thickness" hindering component mounting. (For example, if the board is 3.2mm thick, it could then be difficult to mount certain components (like flat cable connectors) that have shorter pin leads.) And the thickness of PCB is the sum total of the thicknesses of insulating laminate layer(s) and the copper that is clad on it. Though the "solder mask" is an additional layer and so is the legend printing, these typically are "coatings" and hence do not significantly affect the overall board thickness. Even the copper is only microns thick (35 micron for most signal boards and 70 microns for some power supplies) but could contribute a little bit in the case of multilayer boards.

Most digital boards are 1.6mm thick while the "mother boards" for chassis equipments (having mostly connectors to which other boards are plugged in) could be 2.4, 3.2 mm or thicker. And typically these 1.6mm boards have 2 or 4 layers with the laminate taking most of the 1.6 mm. If it's a double side board (or even a single side board), there is just one insulating laminate of 1.6 mm and if it's a four layer board there will have to be 3 thinner layers of laminate sandwiched between the four copper sheets.

And these insulating laminates for double side or multilayer PCBs are usually of FR4 grade or better, while these could be of lower FR grade (FR2, FR3 etc) for entertainment electronics boards that are typically singe sided (audio / TV / toys)

Now what is this FR thing? It is expanded as "Flame Retardant" grade level, as this insulating material should also be thermally insulative as there are possibilities of temperature increase due to various reasons:
a) Electrical current flows through the copper patterns which have some resistance and could generate heat
b) The electronic components generating a lot of heat (think about those power transistors with heat-sinks)
c) The ambient temperature itself could shoot up (e.g. boards used in automobiles or in Rajasthan's desert)

The material of the laminate decides which FR grade it fits in. Some commonly used ones are:

Paper phenolic - FR2 - used in toys, audio, TV etc and appears brown in color. Can easily break:-) For mass production of single side boards, they don't even drill holes but 'punch' using a press tool.

Paper Epoxy -FR3 - used in some telephones where the phone companies like BSNL / MTNL insists it to be of that grade. Yellowish brown, can also be "punched" to make holes

Glass Epoxy - FR4 - This is the green colored laminate used in most professional boards / computers / telecom etc, more suited for DSPTH / ML boards. I have observed some single sided boards without PTH getting punched (especially for thicknesses below 1.6mm), but 1.6mm or above are mostly drilled.

[app_engine]

Another abbreviation that one might encounter in the bare PCB manufacture is 'SMOBC', which is expanded as "Solder Mask Over Bare Copper". Why this term? This has some history.

As briefly mentioned in prior posts, the circuit is etched out in copper. And copper can easily get oxidised. That means, if we store a PCB for a while, it'll lose the "solderability" resulting in poor quality, especially during automatic soldering processes. So, after etching out the circuit, they used to plate the whole area with tin (Sn?) in olden days, and then apply the solder mask (the green colored ink). Those points which are not "masked" will be soldered when passing through the bath. When I started my job as a trainee engineer, this used to be the norm (that of plating complete area with tin and then apply the mask, and this tin plating was a time consuming process as it's basically "electro plating" with baths, electrodes, chemicals etc and messy).

Then the smart machine was developed which could literally "pump" the shiny, tin coating in one quick shot to whichever area got unmasked on the PCB.

So, the process got changed -first apply the solder mask on the "bare copper" circuit, after the unwanted copper is etched out to get the circuit. This becomes "SMOBC"

Then pass the board through this "wonder machine" which coats with the "shiny, tinny" stuff (to all the unmasked area, like component pads etc). This saves a lot of material (which was a waste before being buried under the solder mask).

Old process : drill cu_clad sheets > etch out > tin plating > solder mask
Revised : drill > etch out > solder mask (SMOBC) > "bath" with solder coat in the machine

Big innovation those days!

[app_engine]

Hey we can share the knowledge about designing circuits, so everyone will be benifited.

I don't have even my Basic of Electronics book on hand :(

web irukka bayam edhaRku? google and you'll probably get more info:-)

[sarna_blr]

Enna aachu ...indha hub'ku

Arthi..enga...

[Arthi]

Enna aachu ...indha hub'ku

Arthi..enga...

hub-ku enna aachu oNuum aagala
namba Thread dhan slow-a eruku :P

sorry guys another 10 days i can't peep in here :( :x
I should have something to talk here, I am not practising... just wait for 10 more days :cry:

I will start trying PCB designing again :thumbsup:

[raaja_rasigan]

Enna aachu ...indha hub'ku

Arthi..enga...

hub-ku enna aachu oNuum aagala
namba Thread dhan slow-a eruku :P

sorry guys another 10 days i can't peep in here :( :x
I should have something to talk here, I am not practising... just wait for 10 more days :cry:

I will start trying PCB designing again :thumbsup:

:lol: :) i already told u that hobby cannot become a habit.....

anyway... for me too more work now..... i'll try to post 1 or 2 things per day

[sarna_blr]

Enna aachu ...indha hub'ku

Arthi..enga...

hub-ku enna aachu oNuum aagala
namba Thread dhan slow-a eruku :P

sorry guys another 10 days i can't peep in here :( :x
I should have something to talk here, I am not practising... just wait for 10 more days :cry:

I will start trying PCB designing again :thumbsup:

:lol: :) i already told u that hobby cannot become a habit.....

anyway... for me too more work now..... i'll try to post 1 or 2 things per day

kaNNu pada pOgudhayya chinna goundarE........
umakku suththi poda venumayya chinna goundarE......

[Arthi]

Enna aachu ...indha hub'ku

Arthi..enga...

hub-ku enna aachu oNuum aagala
namba Thread dhan slow-a eruku :P

sorry guys another 10 days i can't peep in here :( :x
I should have something to talk here, I am not practising... just wait for 10 more days :cry:

I will start trying PCB designing again :thumbsup:

:lol: :) i already told u that hobby cannot become a habit.....

anyway... for me too more work now..... i'll try to post 1 or 2 things per day

While writing those sentence, i seriously thought of you and hope that u wld comment
nirubichuteenga :twisted:

hope i will also prove u :thumbsup:

[sarna_blr]

Enna aachu ...indha hub'ku

Arthi..enga...

hub-ku enna aachu oNuum aagala
namba Thread dhan slow-a eruku :P

sorry guys another 10 days i can't peep in here :( :x
I should have something to talk here, I am not practising... just wait for 10 more days :cry:

I will start trying PCB designing again :thumbsup:

:lol: :) i already told u that hobby cannot become a habit.....

anyway... for me too more work now..... i'll try to post 1 or 2 things per day

While writing those sentence, i seriously thought of you and hope that u wld comment
nirubichuteenga :twisted:

hope i will also prove u :thumbsup:

ennanu....that hobby cannot become a habit..... na... :lol:

[raaja_rasigan]

sarna...... post some basic electronics & pcb layout tips (interview point of view)

[sarna_blr]

main question will be...

How many nets will u route perday?

Can u answer for this....with reason...if yes give me...

[raaja_rasigan]

not practical ?'s... some theoritical ?'s like:

Stripline
Microstrip
what is a diff pair... etc. etc.

local-a sonna.... nalla bittu podura madhiri irukkanum

[sarna_blr]

not practical ?'s... some theoritical ?'s like:

Stripline
Microstrip
what is a diff pair... etc. etc.

local-a sonna.... nalla bittu podura madhiri irukkanum

Microstripline....traces routed in top and bottom side....propagation delay is 140ps per inch or 55ps per cm

Stripline...traces routed in inner layers...propagation delay per inch is 180ps per inch or 70ps per cm

Differential pair....already solli irukkEn..irundhaalum..once again

Two signals which have same value but opposite in magnitude

A+ and A- have same value A and opposite in magnitude..(sign)

[sarna_blr]

http://www.ece.arizona.edu/~ece372_spr04/ece372_spr05/References/pcb_xilinx.pdf

lot of useful informations are there......

[sarna_blr]

few informations addition to Strip and microstrips...

For an outer-layer trace (air on one side), the propagation delay is 140 ps/inch, or 55 ps/cm. For an inner-layer trace (FR4 with E = 4.5 on both sides), the propagation delay is 180 ps/inch, or 70 ps/cm.

The voltage-to-current ratio at any point along the transmission line is called the characteristic impedance Z0. It is determined by w/d, the ratio of trace width "w" to the distance "d" above the ground or VCC plane.

For an outer layer trace (microstrip):

Z0=50 ohms when w = 2d (e.g., w = 4 mil, d = 2 mil),

Z0=75 ohms when w = d (e.g., both 2 mil = 0.5mm).

For an inner layer trace (stripline):

Z0=50 ohms when w = 0.6*d (e.g., w = 4 mil, d = 2 mil),

Z0=75 ohms when w = 0.25*d (impractical).

Most signal traces fall into the range of 40 to 80 ohms

[raaja_rasigan]

:ty:

char imp. appadiye manasula padhiya vechuttaen.. so simple while reading here

[sarna_blr]

if u ask question I can answer...in my level...

c..u gave few hints...i was able to answer...so please wt u need...

[raaja_rasigan]

tomorrow going for an interview... vandhu let us discuss.... ippodhaikku enakkum theriyala enna ketpadhendru

[sarna_blr]

congradulations....best of luck...

[Arthi]

tomorrow going for an interview... vandhu let us discuss.... ippodhaikku enakkum theriyala enna ketpadhendru

:thumbsup: sEndru vaarungaL vEndru vaarungaL :thumbsup:

[raaja_rasigan]

:ty:

:nanri:

[sarna_blr]

Hi r_r...this is one of the blog/forum for PCB

u may get better ideas..try

http://blog.ednchina.com/hitwcm/37581/message.aspx

[raaja_rasigan]

tomorrow going for an interview... vandhu let us discuss.... ippodhaikku enakkum theriyala enna ketpadhendru

:thumbsup: sEndru vaarungaL vEndru vaarungaL :thumbsup:

:)

ada neenga vera..... time pass-ku pala peru interview veppanga...
just for an experience i am going........

nalaikku edhavadhu poi sollanum office-la :?

[raaja_rasigan]

ok...... friends... nalai malai sandhippoam...

[raaja_rasigan]

sarna & Arthi...... came to office by 12:30 pm..... just 20 mins interview.... kettavarukke adhigam theriyalai (enakkumdhan)... its a small company, much smaller than my current one....

so.. next company pakkalamnu adha patri marandhuttaen

[Arthi]

hey I was about to ask u abt ur interview
so sweet of u, u shared here :D

yes, jump for a bigger company which has more scope than the current one :D

All the best !!! :thumbsup:

[raaja_rasigan]

?'s asked:

as usual.. strip line, Microstrip - its advantages

good designing - minimise layers & via count

about impedence control boards

& whats ur role in the company / ur clients

[sarna_blr]

sarna & Arthi...... came to office by 12:30 pm..... just 20 mins interview.... kettavarukke adhigam theriyalai (enakkumdhan)... its a small company, much smaller than my current one....

so.. next company pakkalamnu adha patri marandhuttaen

In my opinion...company is not important...how can u expose urself and develop ur skills...that is main...

[raaja_rasigan]

both have advantages & disadvantages, IMO

[Arthi]

both have advantages & disadvantages, IMO
yes IMO company size(either big or small) is not imp, but scope for us is imp
What we can learn from that company is imp

[sarna_blr]

both have advantages & disadvantages, IMO


accepted...only in money wise...

[raaja_rasigan]

when u r in a Big company...... no need to explain much to the interviewer about ur company..... they would have already known it... but if a small company means, need to explain as much as possible so that he comes to a conlusion that it is not a "dappa" company

------------------------------
sarna..... seriously i need to steady my basic electronics..... from monday lets start step by step

[sarna_blr]

surely.......

[sarna_blr]

Hi R_R...Can u post the questions that had been asked in ur interview...let us discuss on that....

[raaja_rasigan]

1) What will be the return path for a signal in a 2 layer board (for a multilayer board, adjacent plane will be return path)

[sarna_blr]

1) What will be the return path for a signal in a 2 layer board (for a multilayer board, adjacent plane will be return path)

ur explaination for return path is wrong...

[sarna_blr]

R_R....

Always signals will be a closed loop....

Let us take one signal as X...and X is going through Y to Z...so the return path should be going through some media so that the loop will be closed.... mostly this return path will be ground...but in some cases pwr will be there...Generally for analog signals we will use analog ground as adjacent plane and for digital signals we will have digital ground as adjacent plane...but wn we r using planes return path will be less...so no problem..

but in case of 2 layers...we should avoid lenghthy routings especially in pwr & gnds....

this is a big topic will continue....

[Bipolar]

I'm not very knowledgable about this topic, but... I think you may find the following textbooks useful:

Practical Electronics Handbook, 6th Ed. (http://rs167.rapidshare.com/files/116041685/Practical_Electronics_Handbook.rar), Sinclair and Dunton.

Radio Electronics Cookbook (http://rapidshare.com/files/21843186/Radio___Electronics_Cookbook.pdf), Brown.

[HonestRaj]

:) [edho niyabagam vandhadhu]

[sakaLAKALAKAlaa Vallavar]

http://www.edaboard.com/


PCB Routing & Schematic Layout software & Simulation
http://www.edaboard.com/forum6.html

etho nammaala mudinjathu :)

[HonestRaj]

Found this to be a useful link

http://www.hardware-guru.net/index.htm

[sarna_blr]

http://circuitcalculator.com/wordpress/

this blog has some useful informations regarding PCB Designing :D

[sarna_blr]

http://www.smps.us/pcb-design.html

[jaaze]

I hate PCB designing :banghead: (hope I won't have it this sem :shaking: )