Should you place solder mask over BGA pads? Do you know why? | Tom Hausherr |
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- เผยแพร่เมื่อ 16 พ.ค. 2022
- How to decide on BGA pad size and if SMD (solder mask defined) or NSMD (non-solder mask defined) pad should be used. I asked Tom Hausherr
You can watch the full interview with Tom here:
• How to create perfect ...
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- Tom Hausherr: / tom-hausherr-cid-cit-4...
- Tom's company website: PCB Libraries www.pcblibraries.com/
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I'm just loving these shorter snippets of useful information! As much as I like the long interviews, it demands some commitment to sit down and absorb it, bite-sized videos are more compelling.
I believe you can specify a negative solder mask expansion on pads etc to achieve that effect. I do that on vias for "tenting" (not true tenting probably but covers majority of the via annular ring)
Maybe a “star” pattern on the pads so there are holddowns around the pad but the solder can get around the pad in 6-8 spots around the pad. Combine both approaches.
Really appreciate these shorter clips, very informative.
Very clarifying, thank you Robert!
great info!
So what happens if you put solder mask the same way as thermal reliefs so not a complete ring but a couple of edges. I guess a straight line like a thermal relief is not a good way but maybe like half circles. That way it kind of looks like a flower pattern from the top. Would the ball be able to collapse partially onto a pad and the parts of solder mask that stick over be able to hold the pad better.
Oooh, I wrote the same thing! Great minds think alike.
Would you also find the same problems with other SMD components with the copper pads ripping off during drop tests/vibe?
I think its harder for other pads since they are generally larger than those tiny BGA pads. Larger pads means more "hugging" to the Epoxy I'd think. Fair warning though, I have never done any vibrational testing but I do PCB design too, simpler stuff.
Simple solution to the pads ripping off: everyone should go back to only using through-hole components! 😂 Just kidding