การปรับปรุงกระบวนการประกอบกล่องโลหะกับแผ่นวงจรพิมพ์ เพื่อลดปัญหาคราบกาวโดยการออกแบบการทดลอง

Saovaluck Bokum; Suwitchaporn Witchakul; Prapol Chivapornthip

Authors

Saovaluck Bokum Master’s Degree Student in Engineering Management Program, Department of Industrial Engineering, Faculty of Engineering, Kasetsart University
Suwitchaporn Witchakul Assistant Professor in Department of Industrial Engineering, Faculty of Engineering, Kasetsart University
Prapol Chivapornthip Lecturer in Department of Industrial Engineering, Faculty of Engineering, Kasetsart University

Keywords:

design of experiments, metal box and printed circuit board assembly process, measurement of resin bleed, shear test

Abstract

In the metal box and printed circuit board assembly process of the case study company, a contract manufacturer of optical transceiver devices, resin bleed exceeding 5.4 millimeters was identified as a critical issue. This problem led to scrap in the gold wire bonding process. The average resin bleed length before improvement was 5.2633 millimeters. This research aimed to reduce the resin bleed length and improve the bonding quality between metal box and printed circuit board. The average shear force before improvement was 11.3946 gram-force. The study investigated the factors affecting resin bleed length and shear force to determine the optimum factors that minimize resin bleed length and maximize shear force. A central composite design was applied. Four factors were studied: epoxy weight, waiting time after assembly at room temperature, surface cleanliness, and epoxy type. The experimental results were analyzed using response surface methodology. The experimental results indicate that the factors affecting resin bleed length are the interaction between waiting time after assembly at room temperature and epoxy type, and the interaction between surface cleanliness and epoxy type. For shear strength, the significant factors include the quadratic term of epoxy weight, the interaction between epoxy weight and surface cleanliness, the interaction between epoxy weight and epoxy type, and the interaction between surface cleanliness and epoxy type. The optimal conditions were: settings were an epoxy weight of 6.91 milligrams, the waiting time after assembly of 41.72 minutes, plasma surface cleanliness, and epoxy type 2. Confirmation experiments with 30 samples demonstrated that, at a 95 percent confidence level, the mean resin bleed length was less than 1.3461 millimeters, representing a reduction of at least 30 percent compared to the pre-improvement condition. Furthermore, the mean shear force was greater than 27.7776 gram-force, which is significantly higher than the pre-improvement condition.

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