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Tue, 24 Jan 2012 23:39:47 +0100 |
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William,
it seems to me as a question of viscosity. Ask for a film with somewhat
higher value or lower the processing temperature. The later will result in
longer processing time, which you may not accept if it's a high volume
line. We have been bonding boards on aluminum heatsinks for years with
Staystik 811 without flowing issues. Just as an example.
Inge
On 24 January 2012 16:18, William Noel <[log in to unmask]> wrote:
> Hello all - We have a project for which every PCB assembly needs to be
> bonded to a heatsink for thermal transfer from the devices on the board to
> the heatsink and out through the Heatsink mounting hardware to the box that
> houses the assembled board/heatsink "modules". One of the requirements we
> have is that when the board assembly is mounted to the heatsink it needs to
> be electrically isolated from the ground potential associated with the
> heatsink and box mounting hardware. As a result, we have used a
> combination of ablefilm and glass microspheres at the bonding interface
> between the board assembly and heatsink. The ablefilm serves as the bond
> and the glass microspheres provide electrical isolation. The problem we
> have consistently had with this process is squeeze out of the ablefilm
> through the holes in the vias of the board. We have attempted to use
> soldermask to tent the vias and thereby essentially seal the top surface of
> the board. This has worked somewhat but we still seem to have problems
> with this approach. Does anyone else out there have experience with this
> and could share some advice with us. Thanks in advance for any help you
> can share.
>
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