Indium Corporation, Nordson to Present Joint Paper at PCIM Asia

August 25, 2021 2:13 pm

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.

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.