Electronics Forum | Wed Apr 08 11:33:51 EDT 2009 | 1036
2) STD FR4 material with HASL finish, 4 layer board. Reflowed under tin-lead temps with another 4 layer board same time(no delamination problem). 3) We uasualy do not pre-bake board unless board is too old. 4) We do not have the board on hand right
Electronics Forum | Fri Apr 21 09:03:59 EDT 2006 | choppy
I guess the first thing to look at is the temperature. We had to heat more for QFP256 on sample boards and we saw discoloration on some small parts. Just try to sense around when profiling to see what's there.
Electronics Forum | Thu Apr 20 22:14:51 EDT 2006 | raquel
hello! need ur inputs... if the Matte Sn pbfree finish of the component discolors AFTER having been exposed to bake, or, after reflow, will the base leadframe have any potential contribution to it? i know most likely suspects would be the plating pro
Electronics Forum | Fri Sep 18 07:32:53 EDT 2009 | karthikthebest
I agree with Graham cooper's input. Also note that the brownish color is incremental w.r.t to number of days you hold after the thermal cycle(example: after the reflow)so try to complete all thermal cycles ASAP to lessen the discoloring.
Electronics Forum | Thu Jan 18 21:52:24 EST 2001 | arul2000
>>>>Dave, The BGA substrate surface finish is NiAu, while the PCBA pad surface is HASL. The solder ball composition is SnPb 63/37 and the solder paste used on the PCBA is also the same but with 2% Silver.>>> Dave, sorry I don't have the picture with
Electronics Forum | Sun Aug 23 11:42:01 EDT 2009 | ysutariya
Hi Dave, I haven't tried the Probimer yet, but the Taiyo ink didn't hold up too well. As a PCB fabricator, finding a white soldermask that has good trace coverage and survives 4X solder immersion (HASL) is like the holy grail of white soldermask.
Electronics Forum | Mon Aug 14 14:27:00 EDT 2017 | emeto
Here is some food for thought. Try to answer these questions yourself and I am sure you will see huge improvement. Reasons: - Bad PCB design - Plating-uneven HASL cause more than OSP Au/Ni or Silver - Poor paste and print quality - uneven paste ca
Electronics Forum | Sat Aug 15 06:29:40 EDT 2009 | abeasia
Help, experiencing discolor of a white solder resist paint after reflow of 250 degree, it turned yellow. Have tried many paints, no luck. Anyone knows one that wouldn't change color and holds the white nicely? Thanks for your support in advance.
Electronics Forum | Wed Sep 09 12:20:28 EDT 2009 | richardli
What is the cause of this discoloarion? Soldermask masterial wrong? Thanks.
Electronics Forum | Sun Aug 16 19:46:48 EDT 2009 | abeasia
Hi Dave F. Thanks for the suggestion, will give it a try. With Appreciation, ABE.Asia
