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1996

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From:
[log in to unmask] (James C. Patten)
Date:
Mon, 4 Nov 96 14:41:55 PST
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>From jamesp Mon Nov  4 13:12:03 1996
To: [log in to unmask], [log in to unmask]
Subject: re: Surface Mount Land Patterns
Content-Length: 799

Gary:

We comply with the principles of "782A" as well. We have higher yields using
the footprints made from this spec. I'm not sure however what you have found
with the chipcaps? My understanding is that the land pattern ranges for "Z"
"G" and "X" dimensions and the 'Jtmin/max' and 'Jhmin/max' dims were compiled 
empirically from the industry? If I apply our company's assy/fab tolerances, 
and establish the manufacturer's tol, I thought that as long as unilateral
tolerances were handled such that the principles for rss'ing toward the MMC/LMC
profile limits allowed any pattern to be created. Are the fillet tables possibly
incorrect? The manufacturer dimensions seem to be consistant with mil/ sheets,
etc.       
                     James Patten
                     TRW Space Electronics

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