CAJ | 학술논문

提出一种基于数值模拟的试验设计方法，研究材料属性和几何结构对多圈四边扁平无引脚(Quad flat no-lead，QFN)封装热疲劳寿命的影响，并进行最优因子的组合设计，以提升热疲劳可靠性。采用 Anand 黏塑性本构模型描述无铅钎料Sn3.0Ag0.5Cu的力学行为，建立三维有限元模型分析焊点在温度循环过程中的应力应变，采用Coffin-Manson寿命预测模型计算多圈QFN封装的热疲劳寿命。采用Taguchi试验设计(Design of experiment，DOE)方法建立L27(38)正交试验表进行最优因子的组合设计。采用有限元分析方法对最优因子组合设计结果进行验证。结果表明，印制电路板(Printed circuit board，PCB)的热膨胀系数、焊点的高度和塑封料的热膨胀系数对热疲劳寿命的影响最为显著；初始设计情况下多圈QFN封装的热疲劳寿命为767次；最优因子组合设计情况下的热疲劳寿命提高到4165次，为初始设计情况下的5.43倍。
제출일충기우수치모의적시험설계방법，연구재료속성화궤하결구대다권사변편평무인각(Quad flat no-lead，QFN)봉장열피로수명적영향，병진행최우인자적조합설계，이제승열피로가고성。채용 Anand 점소성본구모형묘술무연천료Sn3.0Ag0.5Cu적역학행위，건립삼유유한원모형분석한점재온도순배과정중적응력응변，채용Coffin-Manson수명예측모형계산다권QFN봉장적열피로수명。채용Taguchi시험설계(Design of experiment，DOE)방법건립L27(38)정교시험표진행최우인자적조합설계。채용유한원분석방법대최우인자조합설계결과진행험증。결과표명，인제전로판(Printed circuit board，PCB)적열팽창계수、한점적고도화소봉료적열팽창계수대열피로수명적영향최위현저；초시설계정황하다권QFN봉장적열피로수명위767차；최우인자조합설계정황하적열피로수명제고도4165차，위초시설계정황하적5.43배。
A design of experiment (DOE) methodology based on numerical simulation is presented to improve thermal fatigue reliability of multi-row quad flat non-lead (QFN) packages. The influences of material properties, structural geometries and temperature cycling profiles on thermal fatigue life are evaluated. Anand constitutive model is adopted to describe the viscoplastic behavior of lead-free solder Sn3.0Ag0.5Cu. The stress and strain in solder joints under temperature cycling are studied by 3D finite element model. Coffin-Manson model is employed to predict the fatigue life. A L27(38) orthogonal array is built based on Taguchi method to figure out optimized factor combination design for improving thermal fatigue reliability. The optimized factor combination design derived from DOE methodology is verified by finite element analysis. Results indicate that the coefficients of thermal expansion (CTE) of printed circuit board (PCB), the height of solder joints and CTE of epoxy molding compound (EMC) have critical influence on thermal fatigue life. The fatigue life of multi-row QFN package with original design is 767 cycles, which can be substantially improved by 5.43 times to 4 165 cycles after the optimized factor combination design based on the presented method.