Electronics Forum | Tue Apr 11 10:30:46 EDT 2000 | Jeremy Smith
I am having a problem with some joints on a 100 pin pqfp and few different soics on one particular board. When viewed a 8x with a "Mantis" inspection scope the joints look as though they wetted to the ic leg but when probed the leg will pop loose.
Electronics Forum | Tue Mar 25 09:35:28 EDT 2014 | emeto
Have you tried to bake the boards before you process them?
Electronics Forum | Tue Mar 25 10:31:05 EDT 2014 | sara_pcb
The boards are baked for 2 hours at 120 deg C Regards, R.Saravanan
Electronics Forum | Tue Mar 25 08:29:33 EDT 2014 | sara_pcb
Please refer the attached jpegs, The problem is noticed after reflow soldering followed by conventional through hole soldering. Flux used one is MIL Std. Brush cleaning in IPA is followed after each soldering step. regards, R.Saravanan
Electronics Forum | Tue Mar 25 11:25:18 EDT 2014 | horchak
The first impression I get is that the mask was applied over dirty or contaminated copper. What is the trace and land finish on the PCB? You also appear to have a wetting problem.
Electronics Forum | Tue Mar 25 11:43:48 EDT 2014 | sara_pcb
It is Solder Mask on Bare copper, The land finish is HASL as per MIL-PRF-55110G which accepts trace of HASL as acceptable. Wetting is acceptable. regards, R.Saravanan
Electronics Forum | Tue Mar 18 11:53:58 EDT 2014 | sara_pcb
Our contract manufacturing agency have procured pcbs from approved vendor. After assembly we found solder mask separated from the PCB on the epoxy area as patches. The top side is intact. also over the pcb tracks, the mask got damaged. In what c
Electronics Forum | Wed Mar 19 08:38:13 EDT 2014 | davef
I can't picture much of what you're saying, not for nothing, I'm just not connecting. During assembly, solder mask can affected by heat and chemicals. Typically this would be during: * Soldering * Cleaning I will tell you this: Not to defend assem
Electronics Forum | Tue Mar 25 13:55:05 EDT 2014 | horchak
Ok lets put it this way. If the PCB house used a high quality mask and properly applied it to a properly cleaned surface and properly cured it, then as Dave stated above there are only two things that can destroy it. Excessive heat and overly aggress
Electronics Forum | Mon Apr 17 19:30:27 EDT 2000 | Boca
All of the above is good stuff. To add, I have seen this several times if the assembly is wavesoldered. Heat from the wave can partially reflow the top side SM solder joints and weaken them. To test, check joint strength before wave and then after
