Need input on cracked caps/new reflow

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I am wondering how to move from hand soldering our ceramic c... - Nov 07, 2006 by

You are correct that hand soldering ceramic capacitors often... - Nov 07, 2006 by davef

Andrea

#44943

Need input on cracked caps/new reflow | 7 November, 2006

I am wondering how to move from hand soldering our ceramic caps to doing a reflow type process. The reason for the change is too many cracked ceramic caps. I have asked our vendors to assemble our boards via reflow but because of our hardware (swaged standoffs/terminals) they say they can not use a reflow process. We don't want to install hardware after because of component proximety and mechanical stress to smd. Our boards very often have through hole and smd both sides.

I know our company can not be the only manufacturer to have hardware on boards.

So how does a "normal" company utilize a reflow process or how to mitigate cracked caps?

Back ground on the assemblies is the control board is soldered to converter board, converter board is soldered to mother board via headers or terminal pins.

TIA, Andrea

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davef

#44946

Need input on cracked caps/new reflow | 7 November, 2006

You are correct that hand soldering ceramic capacitors often causes them to crack. They do not take thermal shock well. You might be able to reduce the amount of cracking by following the rework repair guidelines discussed in the fine SMTnet Archives. Addirtionally, many ceramic capacitor suppliers provide guidelines for soldering their products.

Your boards sound like the board equivalent of a root canal. If a contractor refuses your product, that's really bad. Those guys will try to build anything. Comments are: * Put PTH on only one side * Put complex SMT on the PTH side, less complex SMT on any side it wants to go * Attach SMT, PTH next, and hardware last

If you continue to allow your designers to do any pinhead thing that pleases them, your boards will continue to be unmanufacturable. Design/Layout rules: * IPC-2221 * IPC-2222

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