Browsing by Author "Cheng, Tung-Hua"

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Analysis of stresses in adhesive joints applicable to IC chips using symbolic manipulation and the numerical method
(2006)
Cheng, Tung-Hua
;
Tseng, Ching-Huan
;
Hung, Ching-Hua
;
機械工程學系
;
Department of Mechanical Engineering
In this study, a concentrated force is applied to both adherends bonded by an adhesive under pin-pin boundary conditions. First a mathematical model is derived with governing equations and boundary conditions. These complicated, and analytically problematic, coupled equations are solved numerically using symbolic manipulation and singular value decomposition (SVD). Also discussed are the effects of major factors, including the relative thickness of adherends, joint length and the action point of the concentrated force on the peel and shear stresses in the adhesive layer. This study identifies the conditions under which the upper adherend without breakage can be fully separated from the lower adherend. Particularly, it is found that the thickness of the lower adherend should be greater than ten times that of the adhesive layer but less than one-third that of the upper adherend, the adhesive layer should be relatively thin (h(a) <= 0.01 mm), and the adhesive joint should be relatively short (thickness to length ratio gamma(1) >= 0.08).
Application of a Genetic Algorithm Associated With Adhesive Joint Analysis to the IC Chip Pick-up Process
(2008)
Cheng, Tung-Hua
;
Tseng, Ching-Huan
;
Hung, Ching-Hua
;
機械工程學系
;
Department of Mechanical Engineering
In the condition investigated here, a concentrated force is applied to both IC chip and blue tape bonded by an adhesive under pin-pin boundary conditions. The experimental results show that even though IC chips of 0.1 mm thickness are subjected to a concentrated force of 4.8 N, they cannot be fully separated from the blue tape and fail easily during the pick-up process. However, when IC chips of 0.34 mm thickness are subjected to a concentrated force of only 3.5 N, they can be fully separated from the blue tape without breakage. These two experimental findings are then explored analytically by applying the C++ program of the genetic algorithm associated with adhesively bonded joint analysis to the IC chip pick-up process. In accordance with the experimental results, the results for the 0.1 mm thick IC chips reveal no solutions for the material properties or adhesive thickness to satisfy the conditions of the IC chip successful pick-up process, although those for the 0.34 mm thick IC chips show solutions for the values of both the elastic modulus and the adhesive layer's thickness. As regards the easy failure of IC chips with 0.1 mm thickness, if the blue tape's mechanical properties are appropriately chosen and then used in this process and its elastic modulus is greater than one-tenth that of the IC chips, the probability of the IC chips being fully separated from the blue tape can be expected to increase. (C) Koninklijke Brill NV, Leiden, 2008