A new spalling mechanism of intermetallics from the adhesion layer in the terminal-stage reaction between Cu and Sn

Microstructural and Mechanical Characterization of Cu/Sn Slid Bonding Utilizing Co as Contact Metallization Layer

“…The reasons of the detachment from inside the (Cu,Co) 6 Sn 5 were detailed in our previous work [35]. Furthermore, according to the results in the current study, the adhesion between Ti and IMCs is weak after the total consumption of the Co and Sn layers by IMCs formation(as seen for Sample A and The detachment of intermetallic compounds from interfaces between solder and the thin wetting layer used in under bump metallization (spalling phenomena) has been discussed in literature [63][64][65][66][67][68][69]. It has been shown that the spalling phenomena, when the large amount of solder remained, appears due to a high interfacial energy between IMCs and an adhesion layer (such as Cr and Ti) [63][64][65][66]68,69].…”

Highly Robust Ti Adhesion Layer during Terminal Reaction in Micro-Bumps

“…Cu-Sn IMCs may spall from the Cr and Ti surfaces when the Cu film is consumed in solid-liquid reactions [2][3][4][5][6][7]. In addition, the spalling phenomenon between the IMCs and Cr adhesion layer has also been observed during the solid-state reaction, which was confirmed by the high interfacial energy between the IMCs and Cr [13]. However, in this study, the SEM cross-sectional results illustrate that the Cu 6 Sn 5 and Cu 3 Sn compounds stably adhered to the Ti surface, as shown in Figure 7.…”

“…Figure 1 presents a schematic of the dimensions of the Sn/Cu/Ti structure used in this study. The detailed procedure for sample preparation has been presented previously [13]. In brief, the samples were first fabricated by electroplating Cu and Sn, sequentially on the Ti adhesion layer, to form micro-bumps and then aged at 200 • C, which could accelerate the IMCs formation to reach the terminal stage of interfacial reaction, for 0, 24, 36, and 42 h to observe the evolution between layers.…”

“…However, fewer studies have investigated the same when the constraint volume of Cu and Sn is simultaneously converted into the full IMC joints in the terminal solid-state reaction. In a previous study, Tsai et al [13] found that when the IMCs were attached to the Cr adhesion layer, Cu 6 Sn 5 and Cu 3 Sn detached and left the substrate during the terminal solid-state reaction. In addition, this spalling process did not dominate the ripening or gravity effects of Cu 6 Sn 5 compared to regular spalling.…”

Robust Cu–Cu Bonding with Multiscale Coralloid Nano-Cu3Sn Paste for High-Power Electronics Packaging

“…Intermetallic compounds (IMCs), which possess high MP, for example, Cu 6 Sn 5 (415 °C) and Cu 3 Sn (676 °C), have been widely investigated in the reaction between the Cu substrate and tin-based solders. − Recently, full-IMC joints, which can be formed at low temperature but can be serviced at high temperature, have been considered to overcome the above-mentioned technological challenges. The full-Cu 6 Sn 5 or full-Cu 3 Sn IMC joints are usually fabricated by eutectic bonding, transient liquid phase (TLP) bonding, and solid–liquid interdiffusion (SLID) bonding technologies. − However, the above bonding techniques may require longer times (for example 120 min, 180 min, and 960 min) to form a thermodynamically stable full-IMC joint.…”