Wetting properties of Nd:YAG laser treated copper by SAC solders

Abstract

Purpose This paper aims to discuss the effect of surface treatment on the wettability between copper and a lead-free solder paste. The industrial applications of laser technologies are increasing constantly. A specific laser treatment can modify the surface energy of copper and affect the wetting properties. Design/methodology/approach The surfaces of copper plates were treated using an Nd:YAG laser with varying laser powers. After laser surface treatment, wetting experiments were performed between the copper plates and SAC305 lead-free solder paste. The effect of laser treatment on copper surface was analysed using optical microscopy and scanning electron microscopy (SEM). Findings The experimental results showed that the wetting contact angles changed with the variation in laser power. Furthermore, it means that the surface energy of copper plates was changed by the laser treatment. The results demonstrated that the contact angles also changed when a different soldering paste was used. Originality/value Previous laser surface treatment can be a possible way to optimize the wettability between solders and substrates and to increase the quality of the soldered joints.

Analysis of Laser Treated Copper Surfaces

“…SEM investigations were carried out using a SEM equipment Philips XL-30 FEG SEM machine. fitted curve on all of the wettability measurements) (Hlinka et al, 2017) …”

“…The laser was used in continuous wave and TEM 00 mode. Argon gas was used as shielding gas to protect the samples from oxidation during laser irradiation with the flow-rate of 12.5 l/min (Hlinka et al, 2017). The laser machine and the layout of the treated samples were shown in Fig.…”

“…This type of copper is widely used for electrical and electronic applications. Before the measurements the copper plates were grinded and polished to remove the oxide layer and reach similar surface properties in every sample and washed with 96% ethanol (C 2 H 6 O) (Hlinka et al, 2017).…”

“…The changes in surface energy were investigated by the contact angle measurement of solders on copper (Hlinka et al, 2017). The wetting experiments were performed in a wetting angle measuring system (Hlinka and Weltsch, 2013) which can measure the wettability using sessile drop method (Abtew and Seldavuray, 2000), taking the methodological issues summarized by Sobczak (Sobczak et al, 2005) into account.…”

Experimental Studies of Different Strength Steels MIG Brazed Joints

“…A lot of paper deals with the modification of surface properties to increase the surface energy (decrease the contact angle to the way of hydrophilic), with these techniques the quality of the joints can be improved. The surface modification could be a laser beam treatment (Hlinka et al, 2017;Verezub et al, 2011). In this study the contact angle represent the quality of the connection between the copper filler wire and the DP, DC steels.…”