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Browse Prior Art Database

Thermal Module Using A Precision Strain Gauge (Resistor)

IP.com Disclosure Number: IPCOM000104783D
Original Publication Date: 1993-May-01
Included in the Prior Art Database: 2005-Mar-19
Document File: 1 page(s) / 38K

Publishing Venue

IBM

Related People

Cain, JF: AUTHOR [+4]

Abstract

Disclosed is a module that develops 1.25 watts @ 5 Vdd. This device will be housed in a 144 lead Plastic Flat Pack (PFP) if thermal profiles of the card permit its use. Ceramic packaging or heat sinks will be necessary if the thermal dissipation for the plastic package is not adequate. The procedure and process used to accomplish this task are described.

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Thermal Module Using A Precision Strain Gauge (Resistor)

      Disclosed is a module that develops 1.25 watts @ 5 Vdd.  This
device will be housed in a 144 lead Plastic Flat Pack (PFP) if
thermal profiles of the card permit its use.  Ceramic packaging or
heat sinks will be necessary if the thermal dissipation for the
plastic package is not adequate.  The procedure and process used to
accomplish this task are described.

      A precision resistor is available that is suitable for use in
this application.  Mechanical analysis measurement systems use strain
gauges that are flat ohmic devices.  The sizes of the gauges vary.  A
commonly used unit was available that would provide the correct
simulation.  This particular strain gauge is a precision 120 ohm unit
that closely matches the size of the device (8 mm).  The following
process was successful in providing a "strain gauge" thermal module:

o   Deprocess an existing 144 PFP using a micro milling machine to
    create a 10mm diameter cavity to a depth just above the die
    plane.

o   Remove the remaining plastic to clean up the die with fuming
    nitric acid.

o   Set the strain gauge resistor directly on the silicon device.

o   Secure the gauge with a suitable adhesive.

o   Solder each side of the gauge to the solder pad and extend the
    wire 12 inches for subsequent connection to a power supply.

o   Refill the cavity with 70% Alumina Filler with Hysol 3028 resin
    and 3416 hard...