Electronics Forum | Thu Jan 08 14:33:50 EST 2004 | dwzeek
Toe fillets are not required per IPC. Toe fillets could be used as a process indicator, if you desire; I would not. Gull wing leads are typically cut off on the ends when manufactured; this exposes the non-plated material in the lead, typically coppe
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 | Tue Dec 14 12:00:34 EST 1999 | Kris Wiederhold
We recently reduced our standard aperture reduction to aid in the reduction of solder on gold defects. Since this reduction in aperture size, we have been experiencing exposed copper at the end of the component pads. The heel and toe joints are per
Electronics Forum | Fri Dec 22 16:04:26 EST 2006 | mika
Hi, This Not so easy as one wuold think. Has the thermal pad of yours vias? How many? What's the via's dia? What is the pcb thickness? If the the pcb has a "ground layer" connected (vias) to the pcb thermal pad, it could sometimes be a little bit tri
Electronics Forum | Mon Jun 27 09:38:30 EDT 2005 | Bob R.
What problems are the quality people seeing? I hope they aren't expecting a toe fillet. QFNs are typically cut from an array after plating. This leaves exposed copper on the sides of the part. We'll often see smearing from the sawing process that
Electronics Forum | Thu Jul 05 15:13:46 EDT 2007 | joeherz
We've seen non-functional QFNs cured by touching up the toe fillets. Especially with parts that are not plated on the edge/face where you get minimal/no wetting due to oxidation of bare copper. I'm not suggesting that you touch everything up but th
Electronics Forum | Mon Dec 18 13:00:34 EST 2006 | realchunks
Hi John, Depending on your board, it could make a difference. Copper finishes might leave that part of the pad exposed, which is a no-no in most places. Where as a HASL board prolly won't care if you pulled the print back. On the other end, over
Electronics Forum | Wed Mar 31 13:05:46 EST 2004 | JoeH
Anyone used this package? It's Cygnal PN C8051F300. The part has bottom side, flat terminations (like a BGA without the balls). There is metalization on the sides of the package but it's not plated (bare copper). Metalization on the bottom is pla
Electronics Forum | Wed Oct 30 02:37:58 EST 2002 | Dreamsniper
Hi Guys, I have a fine pitch QFP that I suspect of having a solderability (wetability) problem. The heel joint is 50%-75% of the lead thickness so it means that I passed the IPC Class 2 recommended criteria on the Heel. The toe has at least 25%-50% s
Electronics Forum | Tue Jun 07 16:19:58 EDT 2005 | davef
Q1) How to identify on good or bad ICs lead that could contribute to dewetting? A1) Distinguish between good or bad IC that could contribute to dewetting by testing for solderability, according to J-STD-002. Q2) What actions that must be taken in fa
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