Analysis of laser metal-cut energy process window

Metal fuses for laser redundant links have been used for years in laser rep air application. Nonetheless, reliability problems have occurred for laser metal cut structures, such as the material leftover remaining at the bottom of the cut site or the formation of a lower corner crack. In this paper, a special finite element Two-Stage Laser Cut Simulation Model (TSLCSM) is pr oposed to study the cut process. Compared with other simulation methods for similar purposes, the proposed model not only includes the stress-relief e ffect caused by cracking and breakthrough of passivation caused by upper co rner cracks, but it also explains the laser-cut mechanism ignoring the meta l underlayer. It proves earlier experimental results that a laser-energy wi ndow exists for each cut structure under a specified laser pulse. Different laser cut structures and different laser parameters are considered in the simulation, and useful guidelines are obtained for a maximum laser-energy p rocess window. Experimental observations consistent,with simulation results show that the differential between upper corner stress and lower earner st ress is temporarily dependent on the passivation breakthrough caused by upp er corner cracks. Also, it is shown that lower corner cracks can be formed at much lower laser energies than previously expected.