J. Micromech. Microeng. 18(2008)105009 CALla anya and K Ta (1)Laminate double Hot-roll laminator lAminate double sist films for 70- esist films for 70- um-thick sacrificial/ anchor layer anchor layer on 18μ m-thick Cu (2) Laminate18μm thick Cu foil (2) Laminate 15-um- other side of Cu foil essex (3)Laminate 1 thick resist 4 UV light (3)Pattern the top ( 4)Pattern the top kpe Mylar Electrode, Anchor (4)Wet etch Cu foil (5)Laminate on the (wEt etch Cu foil workpiece Developer resist in developer and cleaning Figure 3. Two dry-film processes developed for the fabrication of the movable electrode devices on the workpiec tainless steel substrate 3 wafer of Dry-film stainless steel (a)Ar Cu electrodes Patterned copper Figure 5. A6 6 cm- piece of sacrif m photoresist with patterned electrode devices(the 3"wa eath the resist film was placed for dimensional comparisor (a)了 AnchoElectrode layer during the etching process(step b4). Figure 5 shows a piece of sacrificial dry film with arrays of patterned copper electrodes prior to the lamination on a workpiece. After the completion of the electrode fabrication, the protective film of sacrificial resist is removed and laminated on the sample to be machined(step b5). Sacrificial etch is performed in a similar c 4. A SEM image of (a)a fixed-fixed electrode and (b)a manner to that described in process(a) er electrode both with the layouts shown in figure 2, and (c an optical image of the fabricated devices. 5. Experimental results For process(b), the copper foil is laminated with a double- Figure 6 shows a set-up used for uEDM tests as well as layer sacrificial film of PM240 photoresist on one side and with characterization of the electrode structures. The substrate SF306 photoresist on the other side of the foil ( steps bl and b2). with the fabricated devices was placed in an ultrasonic bath The SF306 resist is patterned (step b3)and used as a mask for filled with low-viscosity dielectric EDM oil(EDM 185 wet etching of copper while the protective film of PM240 Commonwealth Oil Co., ON, Canada). A 20 KS2 resistor photoresist is kept intact to avoid any damage to the sacrificial was connected between the device and the dc voltage sourceJ. Micromech. Microeng. 18 (2008) 105009 C R Alla Chaitanya and K Takahata (a) (b) Figure 3. Two dry-film processes developed for the fabrication of the movable electrode devices on the workpiece. (a) (b) (c) Figure 4. A SEM image of (a) a fixed–fixed electrode and (b) a cantilever electrode both with the layouts shown in figure 2, and (c) an optical image of the fabricated devices. For process (b), the copper foil is laminated with a double￾layer sacrificial film of PM240 photoresist on one side and with SF306 photoresist on the other side of the foil (steps b1 and b2). The SF306 resist is patterned (step b3) and used as a mask for wet etching of copper while the protective film of PM240 photoresist is kept intact to avoid any damage to the sacrificial Figure 5. A 6 × 6 cm2 piece of sacrificial dry-film photoresist with patterned electrode devices (the 3 wafer underneath the resist film was placed for dimensional comparison with the film). layer during the etching process (step b4). Figure 5 shows a piece of sacrificial dry film with arrays of patterned copper electrodes prior to the lamination on a workpiece. After the completion of the electrode fabrication, the protective film of sacrificial resist is removed and laminated on the sample to be machined (step b5). Sacrificial etch is performed in a similar manner to that described in process (a). 5. Experimental results Figure 6 shows a set-up used for μEDM tests as well as characterization of the electrode structures. The substrate with the fabricated devices was placed in an ultrasonic bath filled with low-viscosity dielectric EDM oil (EDM 185TM, Commonwealth Oil Co., ON, Canada). A 20 K resistor was connected between the device and the dc voltage source 4