Electronics Forum | Tue Jul 29 03:32:19 EDT 2014 | cmchoue
The solder in MB become to yellowish after thermal test (100 oC/12HR) I think the problem that is flux residue and I really want to know the principle that why it color change Thanks!!
Electronics Forum | Wed Sep 16 00:03:55 EDT 2009 | linseeg
We encoutered few PCB after IR reflow the PCB pad change color from silver to yellowish / brownish. Our IR reflow peak temp is ~250 degree. The brownish cannot be remove with IPA as well. What is the main reason causing this issue?
Electronics Forum | Mon Jan 31 11:28:51 EST 2011 | krisroberson
You stated that you are producing Class 3 boards so I assume you are familiar with the IPC standards.To answer your question directly, I'll refer you back to the J-STD-001. Clause 12.1 states "12.1 Rework Hardware defects shall [N1N2D3] be documented
Electronics Forum | Wed Sep 16 13:32:05 EDT 2009 | davef
Questions are: * What is the solderability protection on the pad that changes color? * What is the distribution of this issue?
Electronics Forum | Thu Sep 17 04:48:51 EDT 2009 | grahamcooper22
The colour you see on the pads is tin/copper intermetallic layer. In your reflow the immersion tin coating and the copper pad underneath react to form in intermetalic layer. The effect is worse the hotter the pcb or area of the pcb gets. In IR reflow
Electronics Forum | Thu Jan 20 08:08:24 EST 2011 | deanm
Because we build Class 3 assemblies, our company has formal inspection steps on our routes. CCA's go through surface mount and then an operator inspects the solder joints for defects and corrects them (touch-up). Following this they go to formal insp
Electronics Forum | Fri Feb 11 13:02:01 EST 2011 | deanm
Thank you for all who read this with interest and especially those who replied. I have considered the points posted and here is what we came up with: We all agree that double inspection is a wasteful operation especially if the operator is more crit
Electronics Forum | Wed Nov 25 10:36:28 EST 2009 | gregoryyork
Is this the Nitric Acid Based Silver finish or the Alkali, I think most are Nitric. Have you tested the solder resist as well for porousity. Cheers Greg
Electronics Forum | Fri Nov 20 14:50:13 EST 2009 | davef
One of our instruments has a high impedance front-end. We: * Passed functional test in the environmentally controlled shop. * Failed test, on the same unit, while carrying it to burn-in chambers in an uncontrolled part of the plant. Solder flux resi
Electronics Forum | Sun Nov 22 09:36:17 EST 2009 | patrickbruneel
Dave, A low residue/No residue flux does exist that when an excessive amount of flux is applied it would only create a cosmetic problem not a reliability issue. The active ingredients are neutralized by the heat applied in the soldering machine and
