'Solder Ball' Formation in Silicon Alloy Transistors

摘要

This report discusses the investigation and solution of the so-called 'solder ball' problem which has plagued the transistor industry for years. Upon investigating silicon alloy transistors which use tin for eletrodes, it was discovered that 'solder balls' (which can cause internal short-circuiting of the device) are not necessarily associated with manufacturing procedures as previously believed, but are produced by the devices themselves because of the material used in construction. Electrical stresses or high temperatures produce balls in units which initially were free of any foreign matter. This is due to the low melting temperature tin alloy used in the transistor's (or other semiconductors) construction. Thus, devices may have balls when put in use and later cause equipment failure. The devices appear good under all measurements. However, when the device is in use, a mechanical shock may shake a ball loose, shorting the transistor and making the circuit inoperable. (Author)