The Accelerated Testing of Plastic Encapsulated Semiconductor Components

Abstract

Elevated temperature and elevated humidity have been studied as stress factors for predicting the reliability of plastic encapsulated bipolar semiconductor components. The test transistors used in the study were encapsulated in a variety of epoxy resins and a silicone resin the purity of which were characterised by a determination of the conductivity of an aqueous extract of the resin.Both stress conditions induce failures-mtodes due to gain degradation, leakage growth and increase in saturation voltages and, under humidity stress, the degree of degradation could be related to the resin purity. It is concluded that elevated temperature is not useful for predicting the reliability of epoxy encapsulated components but is useful-for silicone encapsulated components operating above about 1000C. Humidity stress testing is shown to be valid and relevant for both epoxy and silicone encapsulated components operating below 1000C because of the water that will be present in the encapsulants in normal environmental conditions. It is proposed that the humidity stress factor for life predictive purposesis (RH) because this -is directly related to the water content of the encapsulating resin and can be used as the basis of a physical model -that explains the experimental observations in terms of the ionic impurity content of the resin.

Current‐gain degradation and failure‐rate prediction in bipolar junction transistors

“…For small signal npn transistors encapsulated in either TO94 or 14 lead dual-in line packages, it was reported that the current-gain degradation was about 10% at 1,000 hours and about 40% at 5,000 hours undsr the conditions of 85°C and 85% RH [10]. In our test, only 1.34% degradation after a 1,000-hour test was found for test I.…”

“…Most of these analyses focus on the variations of current gain in short time interval [9,11,15, 16J or on the failure mechanisms of bipolar IC's [13]. The long-term variations of current gain is seldom treated [10,14].…”

“…Therefore, the increase of I C BO may be an indication of the h FE degradation, instead of a sufficient condition for the h FE degradation. Other effects such as metallization corrosion [10] and I EB0 variation [4] should also be considered. Detailed analysis of the degradation model remains to be done through further experiments as well as theoretical studies.…”

“…It contains the information about E-B junction, C-B junction, and base width, etc., and features the device performance. Although its changes with collector current or bias have already been dealt with in many works [9,11,16], its variation with time [10] is seldom treated. The time variations of the current gain under conditions of high temperature and reverse bias are presented here.…”

Evaluation of AlGaInP LEDs reliability based on accelerated tests

“…We have analyzed two humidity models, Lawson [18] and Peck [19] , for degradation failures, best results were obtained with Peck. Fig.…”