Indium Corporation’s Leo Hu, senior area technical manager – East China, and Nordson’s Jonas Chen, China Applications Manager of AXI Products, will co-present a joint paper on using solder-reinforced matrix preforms to increase reliability in power modules and the development of a novel X-ray algorithm to reduce false void detection at PCIM Asia, Sept. 9-11, Shenzhen, China.
In their presentation, Power Modules: Implementing Solder-Reinforced Matrix-Preforms for Increased Reliability & Unique Inline X-Ray Algorithms to Eliminate False Void Calls, Hu and Chen examine the benefits and cost-savings of using a solder-reinforced matrix-preform and how a unique X-ray algorithm can enable 100% inspection of these traditionally challenging-to-inspect parts.
Cracking and solder layer delamination occurs faster in inhomogeneous solder joints due to stress concentration at thinner areas of the joint. Bondline control is, therefore, critical to prevent tilt and achieve a uniform solder joint. Unlike standard solder preforms and their higher cost of production due to necessary additional process steps, a solder preform engineered with an embedded reinforced matrix can achieve uniform solder bondline across the entire solder area, and eliminate all costs associated with the traditional wire spacer stitch and trim technique. Additionally, the innovative matrix design embedded in the solder significantly increases thermal cycling reliability by improving solder creep resistance and suppressing solder fatigue.
Non-destructive inspection of voids in solder joints is crucial in the production process of power modules. While the matrix within the solder preform—and the multiple overlapping solder layers already present within power modules—can present a challenge, autonomous X-ray inspection is the ideal method to solve this inspection task. A special approach was developed that involves an algorithm identifying typical features on the image for the reconstruction. To enable void inspection, the cooling pins (on the backside of the baseplate) are removed during the reconstruction, so that they do not appear on the slice images. Furthermore, due to the presence of the matrix in the solder preform, an additional step is necessary: a unique algorithm identifies and masks the matrix completely, so that it can be excluded from the analysis, enabling stable void inspection.
Hu joined Indium Corporation in 2016 and is based in Suzhou, China. He has nearly 15 years of experience in semiconductor packaging and is a veteran in advanced assembly technology development, process improvement, and assembly materials applications. Hu has served in many roles at industry-leading outsourced assembly and test (OSAT) companies, including process engineer, project engineer, senior R&D engineer, and chief engineer. He has a master’s degree in IC engineering from the Chinese Academy of Science and a bachelor’s degree in electronic information science and technology from Nankai University, Tianjin, China.
Chen joined the MATRIX team in 2012, before the Nordson acquisition. He is based in Shenzhen, China. He has nearly 10 years of experience with inline X-ray inspection systems and is an expert in FATP (Final Assembly Testing), wire-bond, Power Hybrid inspection and in special applications. Chen has served MATRIX, and since 2015 Nordson, in many roles: he began as an engineer, he became a site leader afterwards and currently holds the position of Application Manager in China for the AXI products.