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April 2002

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Subject:
From:
Brent Sayer <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Tue, 2 Apr 2002 13:29:21 -0600
Content-Type:
text/plain
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text/plain (38 lines)
All,
I'm searching for an automated process (conveyorized) to attach heatsinks to
an ASIC (BGAs or CCGAs) component prior to reflow soldering. The
process I'm interested in would attach the heatsink directly to the
1/2" die.
Currently we are using Chomerics adhesive tapes and/or 384 thermal
conductive adhesive with 7387 activator. These solutions, for the most part,
cannot be conveyorized. They are time consuming (Loctite is a 5 min. cure)
or are a poor adhesive (Chomerics tapes have poor adhesion to a 1/2" glass
die).
The ideal process would be able to:
1. Place the ASIC components in wet solder paste.
2. Pick n place the heatsink on to the ASIC component. This may require some
type of liquid adhesive to be dispensed or have an adhesive tape be
preloaded on the heatsink. This is the $1,000,000 question: Is there an
adhesive (liquid, tape or other)that will be compatible with this process?
Some of the problems I foresee are:
The adhesive (liquid or tape) generally require some pressure or force to
make the heatsink adhere to the substrate. Little or no force can be exerted
by the heatsink otherwise the solder paste will short underneath BGAs or
CCGAs.
3. Reflow the solder paste and cure the adhesive (liquid, tape or other)
using a typical reflow profile.
The process sounds relatively easy but after a detailed analysis it is quiet
complex.
Is there a solution?

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