Mike:
I applaud your interest.  Let me just say this however.  When we first
started out w/ SMT, the IPC land pattern manual was nowhere near as complete
as it is today.  We had to do a lot of educated guessing and trial and error
to develop our land pattern library at Nicolet, with mixed results.  Since
the latest revision was released, we have changed or geometries to match the
IPC recommended patterns.  Our SMT yields have increased significantly.

Our policy now is to always start with the IPC recommendation.  We will
modify it after we try it if we find that it needs to be changed to match
our process (which is almost never).

The reason for my writing is not to dissuade you from questioning the IPC
specs but rather to dissuade you from altering the pattern unless you have a
real good reason.  Take advantage of all the work which has come before you.


At 04:48 PM 2/27/96 -0800, you wrote:
>
><Text_1>
>       Our company just started using surface mount components and as I'm
>     creating the land patterns, I notice that on the resistors &
>     capacitors, the width of the part is greater than the width of the
>     pad. What is the reason for this and would it cause a problem if I
>     made the pad the same size as the part?
>
>     Thanks,
>     Mike Wedlock
>     Aerospace Avionics
>
>

-Pat-

-------------
Patrick McGuine
Nicolet Instrument
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(608) 276-6334