Cris Ball,

You sounds like one of those assembly people who say " we
assembled boards this way for 20 years.  Why we have to
change that way"   Excuse myself for side tracking.  I don't get
your point.   You did say wave pad is 2/3 of component width for
15 years.  That is basically what IPC-SM-782 recommends for
wavesoldering chips.  Check at the bottom page of subsection
8.1, subject chip resistors.  It also says about stretching wave
pad in Y-axis as well.

regards
Matthew Park
NII-Norsat International Inc.

>>> Chris Ball <[log in to unmask]> September 24,
1998  5:59 am >>>
Hello all,

Mary. We wave solder a lot of 1206's. Our standard pad config is
2/3 the
width of the part and has been for about 15 years. Every year or
so,
someone comes along and says we should change our pads to
'IPC Standards'.
Where is it documented that the footprint should be 2/3 of the
width of the
part? It would be nice to have a better response than "trust me,
this is
what you want".

Thanks,
Chris Ball
ITT Automotive (formerly Delco Chassis/ soon to be Valeo)





.................
A different footprint is required for wave soldering than is for
reflow soldering.  The wave solder footprint must be narrower to
minimize the amount of solder that is retained.  For wave
soldering,
the width of the footprint should only be 2/3 of the width of the
part.  During wavesoldering, the solder should form a nice
concave
and feathered joint at each end of the component.  The solder
joint
should not be bulged nor should it build up over the top of the
termination.
..................

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