Manufacturing requested something similar for the large pad of our
D2PAK footprint.  The paste stencil has 3 rectangular openings,
sized to deposit paste on about 70% of the pad.

They requested this because a full stencil opening was causing some
sort of problem with excess solderpaste.  Possibly solderballs.
Sorry I can't remember what the exact problem was.  Normally I try
to learn the "why" of things when Manufacturing makes that kind of
request, but it has been a few years.

If your "sketch" below is close to scale, that seems like a very
small amount of paste.  I will echo what is often suggested on this
list: you should run it past your assembly people.

Ron



-----Original Message-----
From: ert ert [mailto:[log in to unmask] <mailto:[log in to unmask]> ]
Sent: Wednesday, July 12, 2006 12:24 AM
Subject: OFN thermal pad pastemask

 Hi All,

I recently captured on a board, the QFN package has thermal pad whose paste
mask is not fully opened but has small square openings as shown below. What
the reason to provide this type of pastemask?

 _____________________
|       ___           ____      |
|     |      |          |      |      |
|     |      |          |      |      |
|      ------           ------        |
|                                    |
|       ___           ____      |
 |     |      |          |      |      |
 |     |      |          |      |      |
 |      ------           ------        |
|                                    |
-------------------------------------

Thanks,
Nagaraj C.I.D

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