Simulation and characterization of a thin film Au/Ni micro hot bridge-wire ignition element under capacitor discharging

Thin film gold/nickel (Au/Ni) micro hot bridge-wire ignition elements with different bridge shapes have been proposed in this paper. They were simulated and optimized using commercial COMSOL software and a finite element (FE) model of the hot bridge-wire ignition elements with different lengths, widths and shapes was set up. Then the simulation of the bridge-wire ignition elements in firing sequence under capacitor discharging has been carried out. The temperature of the hot bridge-wire ignition elements with different lengths, widths, substrates and shapes as a function of the time has been obtained and discussed. It's indicated that the hot bridge-wire ignition element shows a quick response and can rapidly reach the maximum temperature for firing sequence under capacitor discharging. The simulated response time is 0.15 ms. However, this response speed based on the direct current load is obviously too long to meet the fast response requirement in the firing sequence system. One of the advantages of capacitor discharging current is the fast response speed. The micro hot bridge-wire element has been fabricated by surface micromachining technology and then tested using a customized circuitry. Whether the hot bridge-wire ignition element is melted or not can be used to estimate qualitatively whether its maximum temperature reaches the nickel film melting point or not. The test results show that the hot bridge-wire ignition element with zigzag shape can be fused the most easily at the same supplied voltage. It means that this structural bridge-wire element has the highest temperature under supplied capacitor discharging, which is in good agreement with the simulated results.