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Mixed Technology



Mixed Technology | 5 October, 2000

Hi! Does anyone have experience from PCBs with mixed technology. Do you store the PCBs in nitrogen/dry air cabinetts if you�re not able to wavesolder the PCBs within the same day. What considerations need to be taken concerning popcorning/delamination of the SMCs when wave-soldering the board. (Very greatful for any answers.)

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Re: Mixed Technology | 5 October, 2000

It�s funny, the third question on this topic via "Georgia tech..." in the last few weeks. Seems on that particular forum people with the same interests are gathering or maybe they are working all on the problem without knowing about each other.

Daniel: Think of your drying process and your parameters and than consider normal wavesolder conditions. What temperatures will your suspected part see while wavesoldering a) during preheat b) while maybe staying in the hot solder for 3-4sec ? I guess it�s still in the range of your favorite drying temperature (haven�t measured it myself yet), but to be sure take a measurement and you will know how to handle those boards. We haven�t taken any special precautions but that doesn�t mean anything besides the fact that delamination and popcorn related failures didn�t occru to us yet.

Good luck Wolfgang

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Kev Head


Re: Mixed Technology | 6 October, 2000

Most places I've seen don't do anything special. But then again most places only have chip components on the bottom of their boards along with some thru-hole. The best way to find out if you are going to delaminate is to talk to the board manufacturer. Most PCBs are designed to take wave soldering without any special care like nitrogen storage. SMT componets that are designed for wave are the same, but if you have a "special" part, talk to the manufacturer. Give em you process specs of the wave and also the way you plan to store the part while not in use.

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