Browse Prior Art Database

Thermal Shock Resistant Encapsulants Based on Polycaprolactone

IP.com Disclosure Number: IPCOM000116274D
Original Publication Date: 1995-Aug-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 2 page(s) / 31K

Publishing Venue

IBM

Related People

Christie, FR: AUTHOR [+4]

Abstract

The present invention pertains to a low viscosity, low alpha emission encapsulant composed of 100% liquid thermosetting components that have improved thermal shock resistance. This is accomplished by incorporating in the formulation from about 15% to about 30% by weight polycaprolactone oligomers. Such compositions survive 10 ship shock cycles without microcracking where as the unmodified composition shows microcracking after 1-2 cycles. The coefficient of thermal expansion of these compositions is controlled by the use of inorganic fillers free from radioactive isotopes such as uranium and thorium. These fillers contain radioactive impurities of less than a part per billion levels which at higher levels can produce alpha particle emission and as a result cause soft errors in memory chips.

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Thermal Shock Resistant Encapsulants Based on Polycaprolactone

      The present invention pertains to a low viscosity, low alpha
emission encapsulant composed of 100% liquid thermosetting components
that have improved thermal shock resistance.  This is accomplished by
incorporating in the formulation from about 15% to about 30% by
weight polycaprolactone oligomers.  Such compositions survive 10 ship
shock cycles without microcracking where as the unmodified
composition shows microcracking after 1-2 cycles.  The coefficient of
thermal expansion of these compositions is controlled by the use of
inorganic fillers free from radioactive isotopes such as uranium and
thorium.  These fillers contain radioactive impurities of less than a
part per billion levels which at higher levels can produce alpha
particle emission and as a result cause soft errors in memory chips.

Key advantages these compositions provide are as follows:
  o  Improved thermal shock resistance to aggressive thermocycling
  o  Uniform flow and wetting of both the chip and the ceramic
      surfaces securing a good fillet around the periphery of the
chip
  o  Complete coverage of the solder joints
  o  Low alpha particle emission underfill compositions