Ioan,
I hope to address this issue in New Orleans at the IPC mtg there. The
picture and the text are in conflict as they are in several areas in the
manual. You should know that the text takes precedence. The text says that
the solder has not wetted to the land or termination. In this photo, the
one in the DRM, the solder has indeed wetted to the land, although not
completely. If, as it is in this case, the connection meets all other
criteria for that lead or connection style, it is acceptable. If the solder
does not wet the land at all, it would be a defect.
Regards,
Bill Westmoreland
President, BEST, Inc.
Phone (847) 797-9250
Fax (847) 797-9255
Email [log in to unmask]
-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Tempea, Ioan
Sent: Wednesday, October 23, 2002 1:23 PM
To: [log in to unmask]
Subject: [TN] Nonwetting on ImAu, REAL message
Sorry, the finger hit send too fast.
Hi Technos,
I just saw a copy of the desk reference manual IPC-DRM-SMT-C, in normal
language the Surface Mount Solder Joint Evaluation excerpt from IPC-A-610C.
I would need your opinions on the paragraph treating the nonwetting (page
35).
The manual shows a fine pitch IC, on ImAu pads, with pretty uniform and well
wetted joints, but the solder does not go all the way to cover the whole
pad. The tips still show the gold. This is presented as a defect.
Is it really a defect? With extra large pads for fine pitch, we all reduce
the apertures of the stencils. In this situation, there will not be enough
solder to wet all the surface of the pads. What about the homeplated
apertures? No way that the chopped corners will be covered with solder.
So, I guess you know, there are big issues with the inspection.
Please let me know what your experience is with non HASL finishes. Do have
the solder covering 100% of the pad after reflow?
Thank you,
Ioan
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