Gideon Analytical Laboratories received one 2N3700 transistor for failure analysis. A new 2N3700 transistor was also received for comparison. A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power. It is composed of semiconductor material with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistor’s terminals changes the current through another pair of terminals. Because the controlled (output) power can be higher than the controlling (input) power, a transistor can amplify a signal. The 2N3700 NPN bipolar transistor had a collector base maximum voltage of 140V, a collector-emitter maximum voltage of 80V, and an operating temperature range from -55°C to 175°C. The goal was to identify the reason for failure.
Failure analysis was conducted on the 2N3700 NPN transistor. It was sealed in hermetic TO-18 can. Thermal stress was evident. Material pulled away from the lead plating had not affected the hermeticity. The interior showed melted aluminum wire bonds on both sides on the base and emitter. The die was electrically tested and showed normal functionality. The wires showed excessive power, which caused the melting of the entire wire. The ends of the wires balled up as a result of too much power. Although the die has a large black region on the die pads, the die still operated. Under a curve trace, the transistor was within the manufactures electrical criteria. There was another cause for concern. With only the slightest bit of purging, the die came off the header frame. This is indicative of a lateral crack in the die. The die not being attached well was not the cause of the failure, only something to investigate in the future. The cause of the wires both on the emitter and on the base opening up was sustained excessive power.
Gideon Analytical Laboratories has been solving electronics problems for decades. We have helped hundreds of electronics companies save time and money by identifying the causes of failures. Despite the decades of experience, we have not lost our passion and youthful exuberance when it comes to failure analysis. We sincerely enjoy helping, assisting, and consulting with electronics companies and helping them improve their products and their businesses. When you have a failure, call Gideon Analytical Laboratories.