Method for predicting deterioration of grease, grease, and method for manufacturing grease

Patent metadata

Field	Value
Publication number	US-2019302089-A1
Application number	US-201916284512-A
Country	US
Kind code	A1
Filing date	Feb 25, 2019
Priority date	Mar 27, 2018
Publication date	Oct 3, 2019
Grant date	—

Abstract

In a method for predicting deterioration of grease, the grease is applied between a semiconductor module and a cooler. The semiconductor module accommodates a semiconductor element. The method for predicting deterioration includes predicting deterioration of the grease after specified heat cycles by using: a variable G1/G2 that is acquired by dividing an initial storage modulus G1 of the grease by an initial loss modulus G2 of the grease at an expected maximum use temperature of the semiconductor element; and distortion dD of the grease at the time when the initial storage modulus G1 and the initial loss modulus G2 have the same value.

First claim

What is claimed is:

1 . A method for predicting deterioration of grease,
the grease being applied between a semiconductor module and a cooler, and the semiconductor module accommodating a semiconductor element, the method for predicting deterioration comprising: predicting deterioration of the grease after specified heat cycles by using: a variable G 1 /G 2 that is acquired by dividing an initial storage modulus G 1 of the grease by an initial loss modulus G 2 of the grease at an expected maximum use temperature of the semiconductor element; and distortion dD of the grease at a time when the initial storage modulus G 1 and the initial loss modulus G 2 have the same value.

2 . The method for predicting deterioration according to claim 1 further comprising:
acquiring a predicted value A of an increase in thermal resistance of the grease after a temperature change of the semiconductor element from 20° C. to 120° C. is repeated for 200,000 cycles by using Formula 1,
A= 0.001×(22.57−0.7504× dD+ 267.4312×(1− G 1/ G 2))  (Formula 1).

3 . A method for manufacturing grease,
the grease being applied between a semiconductor module and a cooler, and the semiconductor module accommodating a semiconductor element, the method for manufacturing comprising: a deterioration prediction process; and a filler adjustment process of adjusting a contained amount of a filler based on a result of the deterioration prediction process, the filler being contained in the grease,
the deterioration prediction process being a process of predicting deterioration of the grease after specified heat cycles by using: a variable G 1 /G 2 that is acquired by dividing an initial storage modulus G 1 of the grease by an initial loss modulus G 2 of the grease at an expected maximum use temperature of the semiconductor element; and

distortion dD of the grease at a time when the initial storage modulus G 1 and the initial loss modulus G 2 have the same value.

4 . A method for manufacturing grease,
the grease being applied between a semiconductor module and a cooler, and the semiconductor module accommodating a semiconductor element, the method for manufacturing comprising: a deterioration prediction process; and an adjustment process of adjusting a number of crosslinks of crosslinked oil based on a result of the deterioration prediction process, the deterioration prediction process being a process of predicting deterioration of the grease after specified heat cycles by using: a variable G 1 /G 2 that is acquired by dividing an initial storage modulus G 1 of the grease by an initial loss modulus G 2 of the grease at an expected maximum use temperature of the semiconductor element; and
distortion dD of the grease at a time when the initial storage modulus G 1 and the initial loss modulus G 2 have the same value.

5 . Grease applied between a semiconductor module and a cooler, the semiconductor module accommodating a semiconductor element,
the grease comprising a variable G 1 /G 2 and distortion dD of the grease satisfy Formula 2,
the variable G 1 /G 2 being a variable that is acquired by dividing an initial storage modulus G 1 of the grease by an initial loss modulus G 2 of the grease at an expected maximum use temperature of the semiconductor element,
the distortion dD of the grease being distortion at a time when the initial storage modulus G 1 and the initial loss modulus G 2 have the same value,
0.02≥0.001×(22.57−0.7504× dD+ 267.4312×(1− G 1/ G 2))  (Formula 2).

6 . The grease according to claim 5 further comprising:
silica as a filler.

7 . A method for manufacturing grease,
the grease being applied between a semiconductor module and a cooler, the semiconductor module accommodating a semiconductor element, and in regard to the grease, a variable G 1 /G 2 that is acquired by dividing an initial storage modulus G 1 of the grease by an initial loss modulus G 2 of the grease at an expected maximum use temperature of the semiconductor element and distortion dD of the grease at a time when the initial storage modulus G 1 and the initial loss modulus G 2 have the same value satisfying Formula 2, the method for manufacturing comprising: an adjustment process of adjusting a number of crosslinks of crosslinked oil.
0.02≥0.001×(22.57−0.7504× dD+ 267.4312×(1− G 1 /G 2))  (Formula 2)

Assignees

• Toyota Motor Co Ltd

Inventors

• Sasaki Tomo
• Uchiyama Kazunori
• Hakamada Naoki
• Yoshida Tadafumi

Classifications

• G01N33/0047

  Organic compounds · CPC title

• G01N33/2888 Primary

  Lubricating oil characteristics, e.g. deterioration (lubricating properties G01N33/30) · CPC title

• G06F2119/08

  Thermal analysis or thermal optimisation · CPC title

• G06F30/20

  Design optimisation, verification or simulation (optimisation, verification or simulation of circuit designs G06F30/30) · CPC title

• C08J3/24

  Crosslinking, e.g. vulcanising, of macromolecules (mechanical aspects B29C35/00; crosslinking agents C08K) · CPC title