Actually, neither IPC standard requires rework or repair. They require
disposition. Disposition may include rework, repair, use "as is", re-grade .
. . These come to mind.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D.
Sent: Friday, November 17, 2006 10:17 AM
To: [log in to unmask]
Subject: Re: [TN] One solder Ball Not Connected on a No Connect Pad After
Rework
When the pad is lifted, it typically exposes the fiberglass weave underneath
the pad. This allows moisture, flux, solvents, etc, to enter the pwb and
can cause problems later.
The answer to your question depends on what the assembly is used for, and to
what standard do you wish to comply with. IPC 610 and J-STD-001 do not allow
missing pads, they require it be repaired.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of bob wettermann
Sent: Friday, November 17, 2006 9:11 AM
To: [log in to unmask]
Subject: [TN] One solder Ball Not Connected on a No Connect Pad After Rework
This question to the group is about expected solder joint strength on a BGA.
The BGA in question is a 8 x 8mm plastic package BGA using a LF
SAC305 soldering process. It has 64 x 0.018" balls holding it to the PCB.
When removing this device for rework 3-4% of the time one of the corner NO
CONNECT pads comes off.
The question is if we do nothing upon replacement of a new device to the
damaged pad will it really make a difference ??? We are arguing that the
holding strength of the reworked device would be approximately the same
because the change in overall surface area is marginally impacted.
Thanks
Bob Wettermann
Bob Wettermann
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