Design & Manufacturing

Korean Society of Die & Mold Engineering (한국금형공학회)
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Analysis of Wrinkle Defects and Improvement Methods in the Bending Process of PA12 Insulation-Coated Busbars

PA12 절연 코팅 부스바의 굽힘 공정에서 주름 불량 원인 분석 및 개선방안 연구

  • Yong-Jun Jeon (Regional Industry Innovation Department (Growth engine), Korea Institute of Industrial Technology)
  • 전용준 (한국생산기술연구원 지역산업혁신부문(성장동력))
  • Received : 2024.09.13
  • Accepted : 2024.09.30
  • Published : 2024.09.30
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Abstract

This study investigates the causes of wrinkle defects in PA12-insulated busbars used in electric vehicles and proposes an improvement method to address these issues. Busbars, essential components for efficient current transmission in electric vehicle battery modules, require complex three-dimensional bending to optimize internal layouts. For this study, oxygen-free copper busbars with a 0.8 mm PA12 insulation coating were subjected to three types of bending tests: flat bending, edge bending, and torsional bending. Experimental results showed that wrinkle defects only occurred during edge bending, while flat and torsional bending modes exhibited no significant issues. Cross-sectional analysis revealed that the PA12 insulation layer's thickness was uneven, with thinner sections on flat areas and thicker accumulation at the comers. This uneven distribution led to poor adhesion between the insulation and copper layers, resulting in the formation of wrinkles, particularly in areas with air gaps ranging from 75 to 250 ㎛. To further analyze the issue, finite element analysis (FEA) of the bending process was performed under adhesive and non-adhesive conditions. The results confirmed that wrinkles formed when the adhesion between the copper and PA12 coating was insufficient. Improved adhesion conditions, achieved through a heat treatment process at 120℃ for 2 hours, significantly reduced the occurrence of wrinkles during edge bending. This study demonstrates that optimizing the adhesion between the insulation coating and the copper busbar, through controlled heat treatment, can prevent wrinkle defects. The findings provide a pathway for enhancing the durability and performance of insulated busbars in electric vehicle applications.

Keywords

Acknowledgement

본 연구는 한국생산기술연구원 기관주요사업 "제품생산 유연성 확보를 위한 뿌리공정기술 개발(KITECH EO-24-0009)"의 지원으로 수행한 연구입니다.

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