Electronics Forum | Mon Aug 10 12:58:04 EDT 2020 | SMTA-64386637
We have found Acrylic CC under QFNs is a failure mechanism in thermal cycling. The coating acts as a wedge and causes solder joint cracks. We do not coat QFNs. To enhance reliability we have the vias plugged with solder mask. This eliminates some
Electronics Forum | Thu Aug 20 07:11:25 EDT 2020 | sssamw
What your said looks like a acrylic coating thermal expansion causes small solder joint crack. Do you cure coating with heating, or heating after curing? Solder joint crack while you see resistor and QFN trouble? Clear and detail description of your
Electronics Forum | Tue Aug 04 14:29:14 EDT 2020 | dwl
Is the component an LGA or BGA? If its a BGA, it appears like the component is missing balls, if its an LGA, it appears like the solder isn't wetting to the component. What solder are you using? The wetting to the larger pads in the last pic seems
Electronics Forum | Thu Sep 03 01:15:03 EDT 2020 | kylehunter
> I hacked machine to only spend nitrogen when > solder pump is on, this made about 80% save when > you count in frame change, fluxing and operator > slacking Hah! I was thinking of doing just that. What'd you use to trigger the sol
Electronics Forum | Thu Sep 03 22:03:32 EDT 2020 | SMTA-64386139
Both conditions are acceptable for this bottom brazed flat pack package. The solder coverage must be within 0.070 inch of the lead/package interface per MIL-PRF-38535, paragraph A3.5.6.3.4.a. While that requirement could allow for a gold gap near t
Electronics Forum | Tue Oct 06 15:01:33 EDT 2020 | charliedci
We've used glass (pyrex, corningware) bread pans in the past, not filling them much over 1" deep. It takes a while but leaves solder ingots sized well to drop back in. Have not tried lead free yet, the higher temp could be an issue using same ty
Electronics Forum | Mon Oct 12 01:17:00 EDT 2020 | SMTA-64386317
Hi, I am facing high fall out of microphone low sensitivity issues. This microphone is soldering thru SMT soldering with low peak temperature profile which peak at 232 DegC to 240 DegC and have skipped X-Ray inspection but still seeing fall out espec
Electronics Forum | Thu Oct 22 22:01:33 EDT 2020 | SMTA-64386500
Hi John - send me an email (david.hillman@collins.com) and I can send you a few photos of what Mike K. was describing in terms of the solder joint surface being "etched" by the cleaning solution. The dull appearance is due to the abundance of lead o
Electronics Forum | Fri Jan 22 13:22:18 EST 2021 | davidhillman
Hi Graham - brite acid tin gets it "shiny" appearance due to codeposited organic material in the tin plating. The codeposited materials volatilize during the soldering process causing a ton of voids. Brite acid tin plating should not be used as a sol
Electronics Forum | Fri Feb 05 02:40:40 EST 2021 | victorzubashev
For components with the large pads, you can also use secondary soldering dispensing. Some printers like DEK have an option to mount a syringe with an auger valve to do dispensing after the printing step process. Obviously will not work if you have to
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