Publication: Optimization of wire-bonding process parameters for gold wire and aluminium substrate using response surface methodology
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Date
2024-09-01
Authors
Megat Sufi Aniq, Mohamad Rosli
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Abstract
Wire bonding is a connecting technique that uses a combination of temperature,
force, ultrasonic power, and time to attach two metallic materials, a wire, and a bond
pad. In electronics, gold-aluminium (Au-Al) contact wire bonds are widespread due to
corrosion resistance and great conductivity of both metals. However, the intermetallic
compound growth at the metal’s interaction boundary has considerably worsened the
advantageous properties of Au-Al intermetallic system due to the large contact-
potential difference. These intermetallics exhibit low toughness, and possibly low
corrosion resistance, which would result poor bonding quality. This study aims to
investigate the most optimized set of parameters to be used in Au-Al wire bond system.
During the initial study, this research’s starting point is to identify the dependent and
independent parameters within the wire bonding process by using the two fractional
factorial method. After conducting the experiments, data has shown that there are 4
dependent and 4 independent parameters. The four dependent parameters are time of
bond at first bonding site, wire looping height, Y-axis length and ultrasonic force at
second bonding site. These four dependent parameters are brought into extended study
for further analysis. In the extended study, the experimental array was created using a
response surface methodology (RSM)-based design of experiments. The effect of
parameters and their significance to bonding quality in the Au-Al bond system were
studied using analysis of variance (ANOVA). A correlation model was created for the
wire bond strength data. The findings suggest that, within the range of parameters
examined, the proposed correlation model can be utilized to predict performance measures. The optimum value of Au-Al wire bond system parameters was established
at time of bond at first bonding site selected for 300 milliseconds (ms), wire looping
height selected for 1200 micrometre (μm), wire bond Y-axis length selected for 996
micrometre (μm), and ultrasonic force at second bonding site selected for 300 milli
Newton (mN). A validation test was conducted to verify the adequacy of the developed
regression model, and the percentage errors between the predicted and experimental
data were calculated as 0.91% to 7.05%. Thus, the regression model created for this
study are capable of being reasonable accurate. The outcomes of this research add to
our understanding of the Au-Al wire bonding contact for the engineers in the
microelectronics industry and to enhance the wire bond’s quality during the electronic
packaging process.