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Hi tcas, Chris from Worthington Assembly here. We found that when we switched to our super fancy high end reflow oven (that's literally 15 feet long) all those
by EChrisDenney 13y ago
Hi tcas, Chris from Worthington Assembly here.
We found that when we switched to our super fancy high end reflow oven (that's literally 15 feet long) all those sorts of issues kind of went away. Stencil design has a lot to do with it, believe it or not. Too much paste on the center pad and the QFN just floats up and the joints never get connected. So yeah, if CircuitHub just has a footprint for QFN's that's known to work, you can eliminate a lot of that type of research.
- tcas 13y agoI believe that. Even for 0.5mm QFPs, trying to do a stencil at home controlling the amount of solder paste is very difficult. Almost every attempt I've tried leads to at least a few bridges (easy to fix, but still annoying). With the professional machines you guys have it's probably much more reliable even with not so great stencils. Do you end up doing a final DFM as well for most submitted stencil files?
- EChrisDenney 13y agoYeah, every stencil file gets thoroughly reviewed. We reduce aperture sizes for fine pitch components, "window pane" large apertures, round-rects on BGA's, all that kind of stuff. If you choose a CircuitHub approved footprint, all that kind of stuff will be taken care of automatically. Using high-end machines makes life a lot easier too because we have a controlled snap off speed and angle as well as consistent squeegee pressure and paste bead height. You wouldn't believe how many factors go into getting a good stencil print.