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Ruggedized PCB Assembly

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Ruggedized PCB Assembly - 11-/21-07 by Paul M.

Ruggedized PCB Assembly - 11-/21-07 by SWAG

Ruggedized PCB Assembly - 11-/21-07 by davef

Ruggedized PCB Assembly - 11-/21-07 by Real Chunks

Ruggedized PCB Assembly - 11-/21-07 by Paul M.

Ruggedized PCB Assembly - 11-/22-07 by davef

Ruggedized PCB Assembly - 11-/23-07 by Bruce Barton

Ruggedized PCB Assembly - 11-/23-07 by aj

Paul M.

#52608

Ruggedized PCB Assembly | 21 November, 2007

Need some opinions from you fine folks.

We are building assemblies 90% SMT, 10% TH. Fine pitch and BGA devices, etc. The customer is complaining about cold solder joints (SMT) after about 1 year of use, scattered thru-out the assembly, not consistant areas, we haven't actually seen a failed assembly yet, this is what the customer is telling us. The assemblies are visually inspected during manufacturing with no problems seen. The assemblies are used in equipment that vibrates some what and tempertures from 20f to around 125f. The PCB's are ENIG, double sided and we use SnPb solder. Are there some standards to apply to make this assembly "more" rugged? More "robust", last longer? Board finishes, paste, processes,etc?

Your expertise and comments are welcomed.

Thanks.

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SWAG

#52609

Ruggedized PCB Assembly | 21 November, 2007

Maybe you're not be getting all the flux removed in your wash process and your customer thinks the degraded solder joints look cold???

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davef

#52610

Ruggedized PCB Assembly | 21 November, 2007

On one hand, maybe National Aeronautics and Space Administration standards are a good starting point to establish standards for ruggedized manufacturing practice. Look here: http://workmanship.nasa.gov/wkstds_nasa.jsp

On the other hand, as you say, it's really tough to assess a situation with such a small amount of information. Based on what you described, your ENIG boards could have 'black pad' as a possible explanation as good as the next. If that's the case, ruggedizing the board wouldn't change very much.

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Real Chunks

#52615

Ruggedized PCB Assembly | 21 November, 2007

Who is your customer? There are a lto of ways to improve the way you are building. From design to various processes.

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Paul M.

#52618

Ruggedized PCB Assembly | 21 November, 2007

Thanks folks,

Yes, we do not have enough info yet to make decisions at this point.

Just trying to get a feel what folks would do in this case.

Enig,Black-Pad-Nickle skips....Always concerned about ENIG. Silver finish? Is this better?

DaveF, Thanks for the link.

SWAG,

Customer resolders suspected IC lead(s), problem goes away. Not just a visual issue.

It's not a NASA or military app.

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davef

#52620

Ruggedized PCB Assembly | 22 November, 2007

Paul: If your customer "resolders suspected IC lead(s), problem goes away" - It's not an 'black pad' issue. You need to improve the way you solder this product.

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Bruce Barton

#52624

Ruggedized PCB Assembly | 23 November, 2007

Do you have any input as to the vibrations seen on the end-use device? Types of device(s) that have solder joint failure? How many thermal cycles the PCB goes through before failure? There are several areas in production of the board that could be the inducing the problem. Is this infant mortality (new boards) or have these boards been in the field for a while? How are the boards mounted? Do they have vibration isolation? Too many questions to list here. My company is listed on this site...Contact me and we can discuss the details. I AM a consultant, but would be willing to discuss initially free of charge.

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#52625

Ruggedized PCB Assembly | 23 November, 2007

A couple of points -

1.I would recommend that you get your solder paste supplier involved as this could be their issue , let them do some research into proving that its not !

2.Is the problem happening on this product only or do you see it on other products ? If it is just the one product then you can be sure that it reduces the chances of it been your Process.

3.What sort of environment is the product exposed too ?

aj...

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