| 摘要 |
PROBLEM TO BE SOLVED: To determine a soldering temperature which prevents cracks to semiconductor devices on the basis of an interfacial moisture concentration of the semiconductor devices and a heating temperature of a solder bath. SOLUTION: A plurality of semiconductor devices are left in a high-temperature and high- humidity bath having a desired atmosphere condition until the interfacial moisture concentration of semiconductor devices of any kind is saturated. Thereafter, these semiconductor devices are separated to a plurality of groups and soaked in a plurality of solder baths having different heating temperatures. Subsequently, the presence/absence of generation of cracks to the semiconductor device is detected for each semiconductor device. The presence/ absence of generation of cracks is distinguished and plotted for every atmosphere condition where the semiconductor device is left in the high-temperature and high-humidity bath and for every heating temperature of the solder bath. A crack limit graph is formed by connecting limit value plots where no crack is generated. An experimental equation is expressed by Q=C.exp(Ea/kT). No crack is generated if the solder heating temperature T which satisfies Qm>Q is determined wherein Q is the interfacial moisture concentration, T is the solder heating temperature (absolute temperature), C is a crack constant, Ea is an activation energy, k is a Boltzmann constant and Qm is a critical interfacial moisture concentration.
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