Method for predicting strength degradation of sn-based solder alloy joints during high temperature service

Abstract

The application discloses a method for predicting strength damage of Sn-based solder alloy welding spots in high-temperature service, which comprises the following steps: firstly, the tin-based alloy is divided into two types, one is IMC strengthening Sn-based alloy, and the other is solid solution strengthening Sn-based alloy; wherein, under the action of 170 DEG C isothermal thermal load (homologous temperature is 0.8), the strength damage σ of the IMC strengthening alloy welding spot presents exponential decline, and follows the formula: wherein, σ0 is the strength caused by the IMC strengthening part; t is aging time; τ is a constant related to the material. The IMC phase rapidly coarsens, rapidly declines in 0-250 h, and then tends to be stable in 250 h-1000 h, so the welding spot strength is controlled by the matrix Sn, and thus tends to be consistent. The solid solution strengthening Sn-based alloy welding spot keeps stable in the whole aging range.

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