Electronics Forum | Sun Aug 15 04:43:15 EDT 2004 | Danish
Can anyone advise how to measure flatness of a surface?Flatness on top of IC..
Electronics Forum | Mon Aug 16 09:17:13 EDT 2004 | russ
For flatness - Put the part on a leveling plate and roll a dial indicator across it. The leveling plate is not required for a true flatness check but using this will also work for parallelism of lead base to top of body.
Electronics Forum | Thu Sep 11 16:50:18 EDT 2003 | davef
Sure it's conceivable that thin HASL can cause tombstoning. Harkening back to the ample discussion in the fine SMTnet Archives, tombstoning is caused by an imbalance in solder surface tension between the two pads of SMT component. The source of thi
Electronics Forum | Fri Sep 12 09:10:23 EDT 2003 | Norm Morikawa
Around 1989 I had this probelmm with a SMT CCA that would not solder in one area consistently. I had it cross sectioned by the bare board supplier and found that under their metallurgical microscope the thickness of this HASL bare board could not be
Electronics Forum | Mon Nov 20 12:03:42 EST 2006 | ferqs
Good morning Ken, Thank you for your feedback. Just as a clarification, SMD stands for Surface Mount Device. Although my end product, in this case, is a SMD, it might be also referenced as a board. In the other hand, what I get from your feedback i
Electronics Forum | Fri Nov 17 14:36:17 EST 2006 | Fer
Good afternoon all, There is an issue in my company regarding flatness on SMDs. The part I am fabricating is a multilayer assembly of .175" by .175" by .049" thick. The part is made out of a multilayer copper clad PTFE with a tin finish surface. Af
Electronics Forum | Mon Nov 20 19:49:03 EST 2006 | davef
Sorry for stating this incorrectly. It should been: Bow & twist for bare boards and panels: IPC-A-610 Acceptability of Electronic Assemblies, 10.6: 1.5% for PTH only and 0.75% for SMT, acording to test method TM-650, method 2.4.22 IPC-6012, par. 3.
Electronics Forum | Mon Jun 15 16:51:05 EDT 2020 | emeto
Tin/Lead has 183C melting point and probably around 220 peak temperature at reflow. Tin has 232C melting point. I would assume that based on this information you would understand why intermetallic joint is questionable. Go to any flat finish. HASL wi
Electronics Forum | Wed Oct 30 13:35:45 EDT 2019 | emeto
We prefer Flat finish. We don't like HASL.
Electronics Forum | Wed Oct 30 18:19:17 EDT 2019 | slthomas
We use ENIG whenever possible, to the extent that we will try to talk customers out of Pb-free HASL until our keyboard punching fingers bleed. It's much more solderable than HASL and it's flat.
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