PROJECT TITLE :

Competing Fracture Modeling of Thin Chip Pick-Up Process

ABSTRACT:

The IC chip ejecting and pick-up method in electronic assembly plays a essential role in advanced packaging since the success ratio and productivity are determined by the delamination of thin chips from the underlying substrate. For a chip-on-substrate structure subjected to a transverse focused load ensuing from the ejecting needle, a competing relationship between chip peeling-off and chip cracking is discovered from the attitude of integral structure. A competing index, $Gamma$, is defined to characterize the competing fracture behavior between cracking and peeling-off, and therefore the competing fracture mechanism is then uncovered fundamentally. Primarily based on the index, the results of chip geometry on competing behavior are investigated using the virtual crack-closure technique with dummy nodes. Essential thickness and length, which separate chip peeling-off and cracking modes, are found and that they represent the extremity of successful pick-up method. The crucial values are determined by important competing index, $Gamma=Gamma_c$. The competing mechanism uncovered applies to general decide-up method with numerous chip sizes and materials. The crucial sizes and the strategy of evaluating important values are meaningful for chip profile style, optimization of choose-up method, and propelling new styles of electronic assembly process, especially for skinny chips.