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Browse Prior Art Database

Thermistor Bonding Technique to Chipsite Pads

IP.com Disclosure Number: IPCOM000101933D
Original Publication Date: 1990-Sep-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 2 page(s) / 49K

Publishing Venue

IBM

Related People

Gerhart, MS: AUTHOR

Abstract

Disclosed is a technique for bonding a thermistor to a chipsite pad (C4) on a Thermal Conductive Module (TCM) substrate when normal mounting procedures do not exist, or have not been designed into the TCM. This technique is helpful in monitoring the temperature of the TCM during early hardware testing.

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This is the abbreviated version, containing approximately 80% of the total text.

Thermistor Bonding Technique to Chipsite Pads

       Disclosed is a technique for bonding a thermistor to a
chipsite pad (C4) on a Thermal Conductive Module (TCM) substrate when
normal mounting procedures do not exist, or have not been designed
into the TCM.  This technique is helpful in monitoring the
temperature of the TCM during early hardware testing.

      When mounting a thermistor to a TCM, the C4 pads and I/O pins
are mapped into the design of the substrate.  The pads then contain a
higher gold content and are a larger size so the thermistor can be
bonded directly to the pad. If a thermistor is needed after the
design release, another design release has to be done with the
change.  There would be a delay of time before getting the new
substrate back with the thermistor installed.

      The thermistor can be bonded to an unused chipsite engineering
changeable C4 pad by using the following technique.

      The process uses a thermistor (Fig. 1) (unformed leads) and 38
micron gold wire used for TCM substrate jumpers.  The gold wire is
wrapped around the lead twice and as close as possible to the body of
the thermistor (Fig. 2).  The gold wire is soldered to the lead using
a very fine solder and solder tip.

      The C4 pads can have two bonds attached to them.  For extra
strength and reliability, bond both ends of a gold wire to a single
C4 pad (Fig. 3).   Bond the thermistor as close to the substrate as
possible because if the thermist...