Ask him what his rework/touch-up levels are.
Is his assembly captive?
If his process works well with 80% lands than he can build good boards,
but no one else (outside vendors) will be comfortable. My experience is
they like standard footprints (i.e.: SM. 782, SMTPlus, etc.)
The biggest reason to use standards is compatibility.
Good Luck
FNK

Frank N Kimmey
EM Designer
C&K Systems, Inc
(916) 353-5366
[log in to unmask]

> ----------
> From:         scott eder[SMTP:[log in to unmask]]
> Reply To:     TechNet E-Mail Forum.;scott eder
> Sent:         Tuesday, April 21, 1998 9:25 AM
> To:   [log in to unmask]
> Subject:      [TN] SMD Land Patterns
>
> Dear Tech Net,
>
> I have a friend who is considering using a land pattern on a PWB that
> is 80% of  the  minimum part width. This means the part will be (much)
> wider than the pad, which will ensure that there is substantial
> overhang, in many cases outside the J-STD-001 limits.  I am trying to
> convince my friend to abide by IPC 275, but he insists that he always
> uses 80% of the minimum part width and has never seen a problem.   The
> parts in question are standard 0805, 1210 or 1206 R's and C's. The CCA
> should go through a standard solder paste reflow profile.
>
> Can you help me convince my friend to follow the straight and narrow
> path defined by 275? What benefits could I offer to him in adhering to
> standard land patterns? He is a "bottom line" kind of guy (you know
> the type!) and is looking for a "payback" to change his mind.
>
>
> Thanks in advance!
>
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