On July 1st, Toshiba Corporation's Semiconductor Company and Storage Products Company consolidated to form Semiconductor & Storage Products Company.This page describes reliability information of semiconductor products.

Temperature Difference

[As of April, 2011]

Tests for repeated thermal stress from the external environment or internal heat source include the temperature cycle test and thermal shock test. In these tests, the device is subjected to repeated high/low temperature changes to determine temperature change resistance. The failure modes that occur during the tests include bonding opens, aluminum slide, passivation cracks, package cracks, chip cracks and characteristic fluctuation (due to piezo effects).
The temperature cycle test uses a gas as the heating medium, and the thermal shock test uses a liquid. In the temperature cycle test, the device is generally subjected to its high and low storage temperature limits repeatedly. In some cases these limits are exceeded to achieve even greater acceleration. However, it should be noted that, because the test is conducted in device areas having different material physical characteristics, the behavior of the device during actual use may not match the test results.
Figure 1 shows the relationship between the number of cycles and the temperature difference found from the results of a temperature cycle test conducted by Toshiba. Temperature cycle test results can be obtained from the following equation:

A: Constat
α: Acceleration coeffient
N: Number of cycles

From these test results, α = 7.5 is obtained for the aluminum slide failure mode and α = 5.0 is obtained for the package crack failure mode. The lifetime in the field can be estimated from these acceleration coefficients.

This is [Figure 1 Relationship Between Number of Temperature cycles and Temperature Difference].

Figure 1 Relationship Between Number of Temperature cycles and Temperature Difference