Ian,
        as for your comments below, I will vouch for your comments 100%.
        Typically almost 2/3rds of the solder in on a gull wing device is
reflowed to the heel area. Thus where is the strongest portion of the joint?
Typically the toe supplies a place to probe or apply heat from your hand
soldering iron during re-work/touch-up.

        SMT Plus' land pattern designs are designed for a standard paste
application of 6 - 8 mils where the paste mask aperture matches the pad
aperture. They are also significantly smaller then the former IPC land
patterns.

Sincerely,
Brad Velander.

Lead PCB Designer
Norsat International Inc.
Microwave Products
Tel   (604) 292-9089 (direct line)
Fax  (604) 292-9010
email: [EMAIL PROTECTED]
http://www.norsat.com


-----Original Message-----
From: Ian Wilson [mailto:[EMAIL PROTECTED]]
Sent: Monday, August 12, 2002 4:38 PM
To: Protel EDA Forum
Subject: Re: [PEDA] IPC Footprint Standards

<SNIP>

I have read somewhere (maybe "Printed Circuits Handbook" (Clyde, 4th 
Edition), possibly in some notes from elsewhere, that the heel rather than 
the toe is the most critical part of the join (from a strength 
perspective).  Reflow footprints can theoretically have no toe and still be 
reliable at least according to the data I read some year ago.  The obvious 
problem with this is the difficulty of inspection for QA - but these days 
we have that with BGA footprints don't we.  I would not suggest that anyone 
reduces their small device pads this far on my recommendation - I have 
never gone that far.

<SNIP>

I gather the SMC-plus (is that right?) footprint libraries may have 
soldering technology specific footprints - at least someone once told me 
they did.

Ian Wilson


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