关键词: 四侧引脚扁平封装（QFP）, 可靠性, 随机振动, 引脚, 疲劳寿命, 底部填充

Abstract: To address the reliability issue of quad flat package (QFP) devices under random vibration, finite element analysis is employed to evaluate three reinforcement methods: underfill, corner reinforcement, and underfill combined with corner reinforcement. Using the stress-fatigue life (S-N) curve, the fatigue life of pins under random vibration is predicted, and stress distribution/failure patterns of pins are analyzed. Results show that under underfill and combined reinforcement, the primary molding location at device corners is most prone to failure. For corner reinforcement alone, significant stress concentration occurs at the primary molding location of the central pins. The fatigue life cycles are 3.23×10³ (no reinforcement), 3.15×10⁶ (corner reinforcement), 4.33×10⁸ (underfill), and 2.86×10¹² (combined reinforcement). All reinforcement methods improve fatigue life, with underfill outperforming corner reinforcement, and combined reinforcement providing the greatest enhancement.

Key words: quad flat package (QFP), reliability, random vibration, pin, fatigue life, underfill