Electronics Forum | Thu Sep 11 23:50:51 EDT 2003 | Dean
Epoxy is hydroscopic. A cavity will form when the cure furnace reaches the boiling point of water. The steam expansion creates the pocket. It can be large enough to be filled with molten solder from the wave machine and cause a hard short under th
Electronics Forum | Thu Sep 11 15:23:31 EDT 2003 | Peter L.
I have come across a rash of failed assemblies that have 0805 capacitors and resistors, bottom side glued, wave soldered and washed. Trouble shooter reported touching up the solder joints on a few areas and the boards would pass test. I had a look a
Electronics Forum | Fri Aug 26 17:27:48 EDT 2005 | saragorcos
Hello there, Most probably, since the solder balls are entrapped, it is a process indicator, but refer to IPC 610-6.5.3.1 on Excess solder / solder balls / splashes - it really depends on what class you are manufacturing, and the minimum electrical c
Electronics Forum | Mon Aug 29 11:05:10 EDT 2005 | foresiteeric
davef: I am a colleague of Sara at Foresite and we came to the conclusion that the solder balls were entrapped based on the minimal amount of information from the original question and the fact that the x-ray showed the balls and it wasn't mentioned
Electronics Forum | Sun Aug 28 09:23:52 EDT 2005 | davef
Sara Rice: How did you determine the balls were entrapped?
Electronics Forum | Thu Sep 01 09:05:47 EDT 2005 | russ
Thermal pads located underneath leadless devices require a 50% reduction in the stencil aperture.
Electronics Forum | Thu Sep 01 11:25:21 EDT 2005 | chunks
Unless it is peppered with via holes. Then it depends on the size of the pad and via holes.
Electronics Forum | Wed Aug 31 12:49:04 EDT 2005 | kmeline
I have been having the same problem with the LLP. I have three stencil I have done reduction on. The first I went by the manufacturing recommendations. The last two I have done more reducing for the thermal pad. The last one was at a 20% reduction an
Electronics Forum | Mon Aug 29 13:05:11 EDT 2005 | solderguy
Hi All, In IPC-A-610 there is a definition for what constitutes "Entrapped/encapsulated/attached" on page 5-14 in the note. It says that it means that the ball will not be dislodged in the normal service environment of the product. Jim Jenkins
Electronics Forum | Fri Aug 26 10:02:31 EDT 2005 | S vaughan
Hello, Can anyone comment on the implications of small sodler balls under a leadless device such as LLP with a centre thermal land. I believe that we did not make a good reduction and the paste squeezed out of the centre land and balled up under the
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