Reliability Assessment of Copper Wire Bonding under Temperature Cycling Based on Kernel Density Estimation

Wire bonding is one of the mainstream connection methods in current integrated circuit packaging. With the rise in gold wire prices, copper wire has gradually gained wide application due to its lower cost and better electrical and thermodynamic performance. However, the development time of copper wire bonding technology is relatively short, lacking assessment methods for high-reliability applications. Therefore, it is necessary to assess the reliability of copper wire bonding. This paper proposes using wire bond pull force as the assessment parameter. A reliability assessment method of copper wire bonding under temperature cycling based on kernel density estimation is proposed. This method utilizes an adaptive bandwidth kernel density estimation. The difficulties of destructive test data not conforming to common sample distributions are overcome. Finally, a case analysis is conducted to validate the feasibility of this method. The Gaussian kernel function is used to fit the distribution of degradation and the reliability is calculated for 100 ∼ 1000 temperature cycles. A theoretical basis is provided for the application of copper wire bonding in the field of high reliability. The method proposed in this paper can also provide a reference for the reliability assessment of other materials bonding wires.