Abstract
In our previous papers, the dissolution of solid copper into liquid tin and the influences of additional elements to liquid tin were reported as a fundamental research of soldering. The purpose of this study is to make clear the growth process of an alloy layer formed between solid copper and liquid tin which has influence on the mechanical properties of soldered joints. A static study has been made on the process of the growth of the alloy layer under the condition with or without the dissolution of solid copper through the reaction. The results obtained from the experiments at different temperatures in the range 320∼580°C are summarized as follows :
(1) A formula W=b×ta between thickness of alloy layer W and reaction time t was derived for the growth of the alloy layer and the values of a were 0.38 for η phase and 0.53 for ε, δ and γ phases, under the condition without the dissolution of solid copper in liquid tin alloys saturated with copper.
(2) The temperature dependence of b in the formula W=b×ta was found to follow an activation process of the Arrhenius type.
(3) Under the condition with the dissolution of solid copper, the value of a was 1.0, that is, the thickness of the alloy layer increased linearly with the reaction time.
(4) It has be en made clear by microscopic observations that under the condition with dissolution, the alloy layers grew in intensive competition with the dissolution of solid copper.
