Phase growth competition in solid/liquid reactions between copper or Cu3Sn compound and liquid tin-based solder

Abstract

International audienceInterfacial reaction between solid e-Cu3Sn compound and liquid Sn at 250 °C is studied for the first time. The reaction product formed at the e-Cu3Sn/liquid Sn interface consists of the single g-Cu6Sn5 phase. The growth kinetics of the g phase formed at the incremental e/liquid Sn couple (e/g/Sn configuration) is compared to that of g phase formed at the classical Cu/liquid Sn couple (Cu/e/g/Sn configuration). The experimental method con- sists first in processing of intimate interfaces by dipping peaces of solid e-Cu3Sn compound and Cu in liquid Sn for 1 s at 250 °C. Afterwards, isothermal holding of such pre- performed couples for 10, 30, 120 and 480 min at 250 °C are performed for both couples. A theoretical analysis of the growth kinetics of g phase and comparison of its in both configurations are performed

Differences in the interfacial reaction between Cu substrate and metastable supercooled liquid Sn–Cu solder or solid Sn–Cu solder at 222 °C: Experimental results versus theoretical model calculations

“…In order to evaluate the time evolution of the average scallop size we use a simplified model based on the model proposed by [9] (FDR model) and modified by [31]. We will describe the growth kinetics of Cu 6 Sn 5 layer between Cu and the Sn-Cu liquid alloy by assuming that it is controlled by the diffusion of copper through nanometric liquid channels formed between Cu 6 Sn 5 scallops (according to Refs.…”

“…These applications will be performed for T = 222°C but also for T = 250°C by using experimental data of k 2 g and k Ã3 g at 250°C that we have recently published in Ref. [31].…”

“…All calculations details are given in Ref. [31] where it is assumed that the so-called Wagner integrated diffusivities (products D i Dc i of average interdiffusion coefficient D i and of concentration range Dc i ) remains constant during reaction. The ratio between the growth kinetic constants for g (k g ) and e layers (k e ), r = k g /k e , is then given by [31]: and c e given above, Eq.…”

Influence of Copper Pretreatment on the Phase and Pore Formations in the Solid Phase Reactions of Copper with Tin

“…where D = 10 −9 m 2 /s [8], δ = 2.5⋅10 −9 m [8], (C b -C e ) = 8.75⋅10 −3 [8], C i = = 6/11 [8], t = 2 s. In the latter formula, 2 seconds instead of 1 second is taken as a reaction time (the time of the very immersion), since the tin remains liquid for some time after taking the sample out. In the mode of solidphase diffusion in the copper/tin system, the kinetics of phase growth should be determined by the equations derived from the equations of flow balance in the case of plane interphase boundaries [8]. According to the results of work [8], one could expect the ratio of phase thickness to the order of one in the case of solid-phase diffusion annealing.…”

“…In this case, the formation of Cu 3 Sn phase layer during the first second is generally suppressed, and then occurs, but much slower than the growth of Cu 6 Sn 5 [7]. At the stage of operation, when the solder is solid (solid-state ageing), the growth rate of both phases becomes approximately the same [8]. The pore formation with the growth of Cu 3 Sn phase is the main reason for the failure of the soldered contacts.…”