Finite Element Analysis of Weld Area in Spot Bonding Process to Predict Bond Strength in Transparent Materials Using Ultrafast Lasers

Laser spot bonding is an approach to weld transparent materials at micro level or bonding in/for MEMs devices. This manuscript intends to investigate the dynamics of welding procedure in transparent materials with ultrafast lasers acting as the heat source. Spot bonding takes place when a laser beam creates a molten pool of the two materials to be bonded and subsequently the molten materials interact, gel with each other and solidify to create a bond. Thus, predicting the correct amount of molten matter is highly important for a reliable bond. Proper understanding of ultrafast laser matter interaction will provide the means to define ultrafast laser parameters for controlled molten volume leading to controlled bonding strength. This study will utilize the non linear breakdown caused by ultrafast lasers in borosilicate glass to determine the temperature profile and estimate the radial weld area. A finite element (FE) model of the system is presented and solved in ANSYS to estimate the weld area in borosilicate glass strips under action of a single ultrafast laser pulse. The effects of the focusing location of the laser beam, laser process parameters (energy level, focusing lens, pulse width) and material properties (optical and thermal absorptivity) will be discussed.