Hi Robert,
strange name on your company, how do you pronounce it?
To start with, I have pretty much litterature on soldering, but after so
many years confronting soldering, I seldom need look in the book shelf.
However, I did in your case. Wassink has a whole chapter about solder
failures, and in special what he calls ' Soldering Defects Fault Finder
Diagram' Lots of defects are mentioned but not a word about side fillets.
Moreover, most gurus claim, that what is alpha and omega is the solder
fillet between the lead's underside and the solder pad of the board. The
wetting on the sides of the leg, the side fillets, do not play a significant
role according to some authors. Well, that may be so, and the IPC got its
requirements as you mention. Myself, I allow myself to have a quite
different opinion. I've participated in control and inspection documents for
Ericsson for many years, and the operators follow my instructions
meticulously. I mean, that solder fillet on one side only can't be
acceptable for a high quality production process. It has not to do with any
mechanical aspect nor any strength or fatigue calculations. It has simply to
do with the quality of the general lead finish. If there is a one side ony
fillet, we immediately suspect that there may be a plating problem or a
wetting issue. And we never take the risk of accepting such solder joints.
On the 'toe' question, I say it depends on whether the leg is plated befor
or after leg cutting. If the legs are cut after the plating, you cannot
demand solder wettin of course.
The TN gurus will probably do protest, but in this case, I will not take
one step backwards.
Inge
--------------------------------------------------
From: "Robert N" <[log in to unmask]>
Sent: den 18 May 2010 21:07
To: <[log in to unmask]>
Subject: [TN] Acceptabe Solder Fillet on Gull wings
> IPC 610 Cl 2 states that a side overhang of 50% is acceptable. Does that
> means, which seems obvious but not stated, that an acceptable solder
> fillet is
> required on one side only? Does the same apply to the toe, which allows
> for
> an overhang?
>
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