What are the problems when combining three PCBs into one?

[srivatsan]

questions in pcb's

I am plannign to combine three different pcbs into one pcb. what are the possible problems that i may encounter (anything: cost, components, design, etc are all welcome)? if anyone has done this before, then i would like to hear from them. thanks.
srivatsan

 

[binu G]

questions in pcb's

srivastsan
depending on the laout tool you use.
1.mostly you will miss the refference no.because the duplicate ref is not allowed in most of the layout tools.
2. the cost factor can be reduced depending the shape of each pcb.

other way around is if these three pcb are for a single project you can combain the sch of the three and update the reference no and then update it to pcb this can clear the first problem.
but this may need a visual checking too.

i suggest u to combain the three board in a CAM tool.

binu g

 

[srivatsan]

Re: questions in pcb's

i am planning to use PCB123.com's layout software and for verification, right now, i feel CiruitSim might work. i also think i would be having 6 to 8 layers. i have not checked out if it is possible with these softwares. i dont think this project is per se combining three pcbs'. i might have to include interface between the pcb's. so i might be more than "three" pcbs'. well, i would like to know whether there are better softwares available but cannot spend a lot as my manager may not like that!! so let me know any ideas from anyone. thanks in advance.
srivatsan

 

[binu G]

Re: questions in pcb's

hi
if the all the layout is final. then i suggest you to combain the same in the CAM out put tools. like Gerbtool where you can import your files and merge and so on.

Binu G

 

[taring77]

Re: questions in pcb's

i have combined two boards together before but u have to actually ensure that the PCB that you are copying is error free
u might have conflict in Ref Des.
My suggestion is to use cam software coz it werks safely
& it can be say the easiest way to combine them.
depending on manufacturer but in most cases u'll save cost & do think of the way you are going to make the most of panels as some PCB manufacturer counts board in certain sizes.

taring

 

[cyberrat]

Re: questions in pcb's

Redesigning all three into one can give great cost savings, especially if for example there is a PSU section on each etc.
You can make 1 bigger PSU to cover all three, common functions can be combined.

Sections that span over several boards, when combined can give far better EMC & electrical performance, as well as making the reading of schematics much easier to understand as your not having to flick between drawings/boards.

Assembly time for 1 may increase, but it is usually much less than for 3 boards.

Problem wise, if they have different grounding requirements then this can cause problems, differing PSU voltages may mean dragging supply lines to 1 corner when its only used by 1 section that needs to go so far away from the PSU. supplies to the whole board can sometimes induce signals into other sections so it may need to be sub sectioned with filters etc.

Having recently combined approx 5 double sided into a single 4 layer board, it does take some time & lots of thought for getting it to work.
There may be plenty of redundancy in components that are no longer needed or processors that can be combined into 1 etc.

It is also a good time to include all the past modifications, wants & upgrades, also to use new technology & get rid of some components that are going obsolete, so I'd suggest a check on all the major components to see if they are on manufacturers list for going obsolete.

I'd suggest one of the bigger packages like Cadstar etc for a task as this, however as you say your manager wouldn't be so keen on spending too much. Mind you it is most likely possible in even simple packages such as easyPC etc especially as its all in how you prepare the design in the first place.

So get all board & schematics out, find a really big table, get some coffee & highlighters/pencils/erasers & have fun combining them all.

 

[srivatsan]

Re: questions in pcb's

thanks a lot to all of you who have replied. i still need some more information. let me get the process going. i was wondering about the verification of simulation that would be appropriate for such a pcb. let me know if you know. thanks
srivatsan

 

[srivatsan]

Re: questions in pcb's

hi cyberrat,
i have one question specific to you. i did not get PSU = (processor speedup unit or something else). rest were all clear. let me know.thanks.
srivatsan