Reliability of wafer level chip scale package (WLCSP) with 96.5Sn-3.5Ag lead-free solder joints on build-up microvia printed circuit board

Using improved simulated anneal arithmetic to improve semiconductor packaging ball placement process capability

“…The optimum parameter level combination considering the G 0i of grey relation analysis of cost and quality aspects. 11 The degree of relationship among sub-systems or elements could be evaluated through grey relational analysis, [26][27][28] and important influential factors to the development trend are then determined to learn the major features of the system through the following steps: References: Lau and Lee, 1 Lee et al, 2 Tee et al, 3 and Akbari et al 4 *F-value is relative efficiency of factors effect in the Taguchi method. F-value \ 1: the factor effect is small; F-value .…”

“…organic solderability preservative, I-Ag, I-Sn surface-treated board) or nickel base (Electroless nickel immersion gold surface-treated board) in the strong heat, and thus a solid interface IMC is generated. [1][2][3][4]…”

“…1:33 acceptable) as shown in Table 2, meaning the process capability is unstable and insufficient, and there is a large room for improvement. The experiment is designed according to the ball placement process parameters of the case company, and the six most important controlled factors in the experiment are selected from the process parameters according to the field engineer's advice, which are substrate design-Pad Open, Profile type, maximum temperature (°C), solder melting time (s), preheating temperature (°C), and solder ball composition, and the References: Lau and Lee, 1 Lee et al, 2 Tee et al, 3 and Akbari et al 4 Figure 3. Solder ball shear test.…”

“…However, higher strength may be accompanied by IMC (intermetallic compound) layer embrittlement, which may result in another reliability problem; thus, it is not discussed in this study for the moment. 1,[5][6][7][8] The purpose of ball placement is to lay the solder ball on the substrate. The solder ball is the conductor of electrical connection and heat dissipation between the substrate and the mainboard.…”

“…Thus, it is not included in the research scope of this study. [1][2][3][4] This study used the Taguchi method and multiple quality characteristics to calculate the signal-to-noise (SN) ratio and factor level combination from the original data measured after the soldering experiment and took multiple quality characteristics to work out analysis of variance (ANOVA) and contribution rate data, which are integrated into a cross-over analysis table in order to obtain four visualized optimal solutions. The SN ratio was used as an input value, the priority value of various schemes was found by the conversion mode of grey relation analysis, and a rough optimal solution was obtained.…”