Semiconductor device

Abstract

A semiconductor device including: an insulating substrate; a semiconductor element mounted on the insulating substrate; an internal printed circuit board disposed on the semiconductor element; and a sealing member that seals the semiconductor element, the internal printed circuit board, and at least a portion of the insulating substrate. The sealing member is made of a sealant that includes a resin and a pigment, and that initially has a chromatic, white, or gray color, and the sealing member degrades, thereby causing color of a front surface thereof to change to a degree recognizable by a user after the semiconductor device has been in use under a prescribed condition for a prescribed duration.

What is claimed is: 
     
         1 . A semiconductor device, comprising:
 an insulating substrate;   a semiconductor element mounted on said insulating substrate;   an internal printed circuit board disposed on said semiconductor element; and   a sealing member that seals said semiconductor element, said internal printed circuit board, and at least a portion of said insulating substrate;   wherein said sealing member is made of a sealant that includes a resin and a pigment, and that initially has a chromatic, white, or gray color, and   wherein said sealing member degrades, thereby causing color of a front surface thereof to change to a degree recognizable by a user after the semiconductor device has been in use under a prescribed condition for a prescribed duration.   
     
     
         2 . The semiconductor device according to  claim 1 , wherein said pigment has a blue color so that a b* value within a L*a*b* color space of the front surface of said sealing member is −40 to −20. 
     
     
         3 . The semiconductor device according to  claim 2 , wherein the b* value of at least a portion of the front surface of said sealing member changes to −5 or above as a result of degradation of said sealant. 
     
     
         4 . The semiconductor device according to  claim 1 , wherein said pigment has a blue color and the sealant further includes another pigment that has a yellow color, so that an a* value within a L*a*b* color space of the front surface of said sealing member is −30 to −15. 
     
     
         5 . The semiconductor device according to  claim 4 , wherein the a* value of at least a portion of the front surface of said sealing member changes to −5 or above as a result of degradation of said sealant. 
     
     
         6 . A device, comprising:
 a printed circuit board; and   the semiconductor device according to  claim 1  mounted in a plurality on the printed circuit board.   
     
     
         7 . A method of estimating remaining life of a semiconductor device that includes a sealing member made of a sealant, the sealant initially having a chromatic, white, or gray color, the method comprising:
 heating a test sealant that has the same composition as the sealant in the semiconductor device at prescribed heating temperatures for prescribed durations;   acquiring a relationship among the heating temperatures, heating durations, and resulting changes in color of the test sealant, by observing the color of the test sealant while the test sealant is being heated; and   estimating the remaining life of the semiconductor device that has been operated, by evaluating color of a front surface of the sealing member in accordance with the relationship acquired in the step of acquiring said relationship.   
     
     
         8 . The method of estimating remaining life of a semiconductor device according to  claim 7 , wherein the color of the test sealant is quantified using a L*a*b* color space in the step of acquiring said relationship. 
     
     
         9 . The method of estimating remaining life of a semiconductor device according to  claim 7 , wherein the step of heating includes:
 preparing a test semiconductor device having the same structure and composition as the semiconductor device of which the remaining life is to be estimated;   operating the test semiconductor device under a prescribed condition for a prescribed duration;   measuring a temperature of the front surface of the sealing member of the test semiconductor device while the test semiconductor device is being operated; and   observing changes in the color of the front surface of the sealing member of the test semiconductor device while the test semiconductor device is being operated.   
     
     
         10 . A method of verifying the quality of semiconductor devices, comprising:
 mounting a plurality of semiconductor devices, each including a sealing member formed of a sealant that initially has a chromatic, white, or gray color, on a substrate;   comparing degrees of discoloration of the respective sealing members in the plurality of semiconductor devices to one another; and   determining that the plurality of semiconductor devices are in good working condition when the step of comparing does not show a prescribed degree of variation in the degrees of discoloration among the plurality of semiconductor devices, and determining that the plurality of semiconductor devices are not in good working condition when the step of comparing shows the prescribed degree of variation in the degrees of discoloration among the plurality of semiconductor devices.