Abstract
Ultrasonic-assisted soldering, as a type of new welding method, is widely used in the field of electronic packaging. This research used the immersion method to study the dissolution behavior of copper in liquid tin and the growth of IMC at 513, 543, and 573 K with/without ultrasonic waves. The amount of copper dissolved and IMC layer thickness were measured and the dissolution activation energy of Cu/Sn was calculated. Experimental results indicated that Without ultrasonic waves, the amount of copper dissolved increased nonlinearly with immersion time. However, with ultrasonic waves, the amount of copper dissolved increased linearly with immersion time. The amount of copper dissolved in liquid tin increased considerably with ultrasonic waves, and the dissolution rate increased by 7–8 times. The thickness of the IMC layer decreased as the ultrasonic time and ultrasonic power increased. Meanwhile, the ultrasonic waves reduced the dissolution activation energy of the Sn/Cu system.
Highlights
As a key process in the electronic packaging industry, soldering is expected to meet new demands with the development of integrated circuits in the sub‐micrometer and deep sub‐micrometer range
The dissolution rate of the copper matrix in liquid tin is usually expressed by the following equation[12,13,14]: ( ) = dC / dt where C is the concentration of copper in liquid tin after immersion time t, K is a dissolution rate constant, A is the interface area between copper and liquid tin, V is the volume of liquid tin, and Cs is the saturation concentration of copper in liquid tin
In this study, when the copper wire was inserted into liquid tin, on the one hand, the copper atom was directly dissolved into liquid tin, and on the other hand, an IMC layer was formed on the surface of the copper substrate
Summary
As a key process in the electronic packaging industry, soldering is expected to meet new demands with the development of integrated circuits in the sub‐micrometer and deep sub‐micrometer range. Several new soldering techniques have received attention As one of these methods, ultrasonic-assisted soldering has been widely used for electronic packaging. Compared to the traditional soldering method, ultrasonic‐assisted soldering can promote the wetting of solder on the substrate[1,2], remove the oxide film on the surface of the substrate to avoid the problem of residual corrosion of the joint interface flux, and refine grains to improve the shear strength of the solder joint[3,4,5]. It is suitable for the connection of complex shapes and structures. It is necessary to study the dissolution behavior in the reaction system with ultrasonic waves
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