I not sure I understand what you're saying about your customer's
requirement, but appreciate your concern about printing too much paste and
floating the part.

We assemble with EPTSSOP [Exposed Pad Thin Shrink Small Outline Package]
parts, which sounds similar to your part.  EPTSSOP increases the thermal
efficiency of power constrained standard TSSOP packages by as much as 150%
by soldering the heat sink pad on the bottom of the package to the board.

Apparently, Amkor [the part fabricator] is particularly optimistic about our
ability to assemble boards with these parts.  So, they provide virtually no
information on their site, other than "use standard processes".  [er, words
to that effect]  We printed various paste volumes, placed, reflowed, and
sectioned dummy parts from Practical Components [probably Top Line and
others have similar parts].

If your customer is asking you to prove that there is solder coverage of the
gold pad for the heat sink after soldering,
* Why not just pop the part off the board with a beer can opener?
* Never tried this, but wont your xray machine show this?

Dave Fish
----- Original Message -----
From: "Andre Leclair" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Tuesday, October 23, 2001 11:39 AM
Subject: [TN] SMT part with Backside Ground


> Hi All
>
> Hope some one can help?  We have have a board from a customer which has a
> PSSop-16 with a Backside Ground ( #RF2119DBP).  The stencil house has made
> a cutout that is slightly smaller then the ground on the device.  The
> ground plane area on the card is basically the size of the body of the
part
> with 10 via holes in it.
> The customer wants evidance of solder reflow on the ends (Tinning of the
> Gold Plate).  Current stencil does not get enough paste to do this and we
> are concerned that if we make the cut out larger then the device contact,
> the part may ride on top of the extra solder and result in
> opens/insufficients on the leads.  Also I have been unable to find a
> recomended land/paste pattern for this type of device.
> Any ideas would be appreciated.
>
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