[hpsdr] Sl\older Reflow Problem

[bstrick at n5brg.com]

Hi Horst, DL6KBF

Your problem looks a little strange and I can offer a few comments:

It may be that your PCB was not dry and moisture was working its way out of the PCB and delaminating the solder mask material. The solder mask material may have also contained moisture or not been completely cured.

If this is the condition you have you may correct the problem by baking the PCB. The exact time and temperature needed may be determined by testing. I would start with a bake at 100 C for a minimum of 10 hours. This should dry out the moisture. You will need to solder the boards very soon after drying them or protect them from reabsorbing moisture.

The black material is more troubling. Could this material be something placed in the reflow furnace that should not have been there? Some low temperature plastic material that melted and found its way through the holes in the PCB. That is what it appears to be.

Double check the solder reflow profile temperatures. Be sure your furnace temperature is correct. The temperature you reported sounds low for a typical reflow profile but the results may indicate the temperature was much higher than you thought.

Your boards and components should have a JEDEC moisture sensitivity level (MSL) rating. This rating gives you information on how fast the parts absorb moisture. This is typically not as much of PCB problem as it is for the parts.

Hope this helps.

Bob, N5BRG


-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.openhpsdr.org/pipermail/hpsdr-openhpsdr.org/attachments/20070506/77f98f72/attachment-0003.htm>