Electronics Forum | Thu Mar 29 08:28:28 EDT 2012 | williamaxler
In the IPC-A-610E standard QFNs are classified as BTC (bottom termination components). Most QFNs do not have a solder-able surface on the outside of the part. Usually the lead that you can see on the outside is copper and classified is not solder-a
Electronics Forum | Thu Aug 10 11:24:18 EDT 2017 | dleeper
The exposed metallization on the sides of the QFN probably aren't tinned and therefore not expected to have solder wetted to them. If previous parts formed nice toe filets, it might just be that those parts were fresher and the exposed metal did not
Electronics Forum | Wed Nov 15 12:52:21 EST 2017 | georgetruitt
IMO – Look into nano-coatings for your stencil and radius all square apertures This should help out with solder paste releasing from the stencil helping with insufficient solder QFN LGA aperture design, try a stencil cut with a few different apertur
Electronics Forum | Wed Mar 31 20:34:03 EST 2004 | davef
We have not used this specific package. We agree on your toe fillet idea. Toe fillets add no strength to solder connections. This part is a MicroLeadFrame�, which is similar to QFN, BCC, LGA, and whatnot. Consider: * Searching the fine SMTnet Arch
Electronics Forum | Fri Jun 20 18:32:55 EDT 2008 | hegemon
Back when I used to do a lot of these style devices we ran into the same problem you are describing. Use a pattern for the center pad area and keep the total coverage to about 68% of the pad area. Diagonal Stripes, tic tac toe, cloverleaf, dot array
Electronics Forum | Mon Feb 28 12:01:30 EST 2005 | Bob R.
We use QFNs in automotive products and have done a good bit of experimenting with pad designs, paste patterns, stencil thickness, and thermal via patterns. All of them have an effect on assembly and thermal cycle reliability. There is not a yes or
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