Electronics Forum | Fri Nov 08 17:20:52 EST 2002 | davef
You need to get as much paste on the board as you can get. A BIG opening gives: * Better release. * More paste. You may be able to cheat further by rotating the square so that it is on the diagonal.
Electronics Forum | Fri Nov 08 17:10:04 EST 2002 | rspoerri
Is that square inscribed or circumscribed with respect to the pad? It sounds like you're saying circumscribed (overprint) given the volume comment. Wanted to confirm though. Kim
Electronics Forum | Thu Nov 07 09:23:05 EST 2002 | russ
What would the considerations be in utilizing a type 4 paste as opposed to type 3? We have an assembly that has a large amount of uBGAs (12 mil diam pad)along with 50 mil pitch BGAs assorted fine pitch etc... We are experiencing difficulty in paste
Electronics Forum | Thu Nov 07 10:59:11 EST 2002 | pjc
IPC-7525 "Stencil Design Guidelines" is a good reference document to have. Here are notes from a Tessera, (a major mBGA mfg.), study- "Application Note Solder Stencil Requirement for mBGA" The stencil aperture is to be square, equal in size to the l
Electronics Forum | Fri Nov 08 14:48:58 EST 2002 | davef
Yours is (12 thou x12 thou)/(2x(12 thou +12 thou)x5 thou) = 0.60 * Aspect=W/T for electroformed stencils SB GT 1.1 => Yours is 12 thou/5 thou = 2.40 So, we kind of think of what you�re trying do as maybe printing a 16 pitch QFP, which gives you simi
Electronics Forum | Thu Nov 09 20:01:12 EST 2006 | AB
What are the pros and cons between type 3 and type 4 no clean solder paste (SnPb)?
Electronics Forum | Sat Nov 11 07:54:53 EST 2006 | davef
Many use the following guideline when judging the proper paste for a stencil aperature: You want approximately 5 particles minimum across the smallest aperture.
Electronics Forum | Fri Nov 10 09:13:34 EST 2006 | russ
Dave hit the cons pretty well for type 4 type 4 is used when you have extremely small apertures and type 3 will not fit into them or release adequately basically. I have not yet had application that requires it but got very close once, .007 circle
Electronics Forum | Thu Nov 09 23:01:34 EST 2006 | davef
Tin/lead alloys tend to oxidize very easily, affecting solderability. Use the largest particle sized paste possible, because as the particles decrease in size their total surface area per unit mass increases, effecting: * Demands on the flux increase
Electronics Forum | Wed Sep 04 07:15:02 EDT 2013 | anilw2006
We have using SAC305 type solder paste for lead free process. One sample paste received of SN100C.After reflow SN100C type paste joint looks brighter and good compare to SAC305. Please help me which paste is good for smt process?
