Linden,
Given the two footprint documents, IPC vs the manufacture's ,  I will always
use the manufacture's first.   The manufacture has generally  allowed for
tolerances specifically designed for their part.   Under some circumstances,
I have had  large contract manufactures provide me with very  specific
design guidelines which altered footprints for their  reflow process.  One
claimed since he was also responsible to his client to provide warranty, any
percent of increased reliability =  one percent of his profits.   I would
set the precedence to follow the manufacture's guidelines then IPC.  (which
by the way is very good)


Mike Reagan





----- Original Message -----
From: Linden Doyle <[EMAIL PROTECTED]>
To: PEDA <[EMAIL PROTECTED]>
Sent: Sunday, August 11, 2002 10:36 PM
Subject: [PEDA] IPC Footprint Standards


> Greetings all,
>
> I have a copy of IPC-SM-782. In it are described various recommended
> footprints for resistors, capacitors, discrete semis and ICs.
>
> I also have some documentation from Philips Semiconductors describing the
> same items.
>
> The problem is that the sizes represented in each publication are vastly
> different.
>
> What dangers are there in straying from the path prescribed by the IPC? If
I
> work from the Philips documents I have smaller footprints for things like
> generic 0603 and 0805 thus allowing for tighter layouts. My copy of
> IPC-SM-782 is date 1993 - is it likely that the footprint recommendations
> would have changed in later revisions of the standard?
>
> My previous surface mount boards have not been overly tight but this is
not
> the case with the latest job - I need all the space I can get.
>
> Any comments would be greatly appreciated.
>
>
> Thanks and Best Regards,
>
> Linden Doyle
> Product Development Engineer
> Zener Electric Pty Ltd.
>
> Ph: +61 2 9795 3600
> Fax: +61 2 9795 3611
> [EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]>
>
>
>
> ************************************************************************
> * Tracking #: 7AE998780E1AD14BA518CF969F9E79261307E4BB
> *
> ************************************************************************
>

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