The Fabrication Of MEMS Fuze Safety Device And The Study On Bonding Strength Of Electroforming Layer

With the development and wide application of MEMS technology, MEMS fuze safety device is developing very quickly. It tends to replace the traditional mechanical fuze safety device in large field. In order to obtain a high-performance fuze, it is very important to control the volume effectively. The MEMS fuze safety device can satisfy the requirement perfectly. It is much smaller than traditional one, therefore the fuze can have more space for the multi-sensor detection circuit and the main charge, and the fuze accuracy and destructive power will be greatly improved. In addition, The MEMS fuze safety device takes many other advantages which have attracted considerable interests, such as low cost, small weight, high strength and high reliability.In this paper, comparing the existing technologies in fabricating MEMS fuze safety device, a new micro fabrication method of metal-based fuze MEMS safety device is presented based on UV-LIGA technology. The method consists of SU-8 thick photoresist lithography process, micro electroforming process, no back plate growing process and SU-8 photoresist sacrificial layer process. Two kinds of double-layer moveable metal devices have been fabricated on metal substrates directly with the method. Because UV-LIGA technology and no back plate growing technology were introduced, the production cycle was shortened and the cost was reduced. The smallest dimension of the devices is 40μm, which met the requirement of size. To evaluate the adhesion property between electroforming deposit layer and substrate qualitatively, the impact experiments have been done on the device samples. The samples were still in good condition and workable after undergoing impact pulses with 20,000g peak and 150μs duration and completely met the requirement of strength. Besides, six problems in the fabrication process have been solved effectively, which is helpful for the fabrication of similar kinds of micro devices. The fabrication method presented in the paper provides a new option for the development of MEMS fuze.Besides, the mechanism of electroforming and the factors that influence the bonding strength of electroforming layers have been discussed. Comparing different testing method of film-substrate bonding strength, scratch tests have been done to evaluate the bonding strength of Ni layers, and the samples were electroformed under different current density. The result has been discussed, which made a preparation for the further work.