Improvement of Joint Reliability of Sn-Ag-Cu Solder Bumps on Cu by a Laser Process

Abstract

Laser soldering has recently been introduced in industry because of its unique properties, which include localized and noncontact heating, a rapid rise and fall in temperature, and easy automation compared to reflow soldering. In this study, the effect of an annealing treatment on the impact strength of solder bumps heated using the laser process was investigated to improve the impact reliability of soldered joints. It was found that, in the as-soldered condition, a thin intermetallic compound (IMC) layer was formed at the interface of the solder bumps on a Cu pad when using the laser process with and without annealing. After aging at 150°C, the impact reliability of the solder bumps heated using the laser process with annealing was superior to that of the solder bumps heated using the laser process without annealing. This was because the IMC grains at the interface clearly grew to a large size. These were effective at preventing Cu atoms from diffusing to the interface of the joints soldered by the laser soldering process and may be the reason that the annealing treatment at 20 W for 5 s prevented the degradation of the maximum load of solder bumps when using the laser soldering at 40 W for 1 s.

Burnout mechanism and control methods in laser soldering

“…The problem of overheating damage of heat sensitive components is solved by laser soldering because of the advantage of local non-contact heating [3][4][5]. In order to better utilize the advantages of laser soldering, many scholars have carried out a series of studies on wettability, mechanism of intermetallic compound generation, and mechanical properties of solder joints [6][7][8].…”

A data-driven framework to predict the morphology of interfacial Cu6Sn5 IMC in SAC/Cu system during laser soldering

“…The attributes such as precisely focused laser beam, localized and non-contact heating, rapid rise and fall in temperature, large cooling rate, short duration etc. make laser soldering a better choice over reflow soldering [6][7][8] . Nishikawa and Iwata [9] have found out that the solder joints processed by laser has superior impact reliabilit than those prepared by conventional reflow soldering.…”

“…make laser soldering a better choice over reflow soldering [6][7][8] . Nishikawa and Iwata [9] have found out that the solder joints processed by laser has superior impact reliabilit than those prepared by conventional reflow soldering. Moreover, the growing popularity of laser in flexible electronics [10] , additive manufacturing (3D printing) [11][12][13][14] and biomaterials fabrication [15] sectors, has attracted a great attention from researchers, and study of laser heat source on any materials system can aid in understanding the mechanism of laser-materials interaction.…”

TEM observation of interfacial compounds of SnAgCu/ENIG solder bump after laser soldering and subsequent hot air reflows

“…Recently, laser soldering, as a new and unique soldering process has been introduced into the electronic packaging industry [1,2]. Compared with the conventional reflow soldering processes, laser soldering shows obvious advantages for solder bumping in ball grid array (BGA) electronic packages, due © 2015.…”

“…This manuscript version is made available under the Elsevier user license http://www.elsevier.com/open-access/userlicense/1.0/ 2 to its unique properties such as localized and noncontact heating, fast heating and cooling. [1][2][3][4]. By laser soldering, lead-free SnAgCu solder balls are melted and metallurgically soldered to metallic pads to form solder bumps, which inevitably experiences subsequent multiple reflows during multi-assembly in 3D packaging and assembly technology [5,6].…”