PI2525 Polyimide Recipe v 1.1, 25 April 2001 *** 50 um wide flexures with 4 um thick polyimide *** see data sheet at www.hdmicrosystems.com warning- wear coat, latex gloves, goggles and work under fumehood with polyimide o (if not already in small container, thaw PI2525 and pour into small plastic bottle. cap tightly after use) replace PI2525 in freezer * warm to room temperature - I suggest a warm water bath for the small bottle. Cooler temperature will be viscous and too thick * o prepare slide with double sided GelPak X4 to hold SS o attach 12 um stainless, sand lightly with silicon carbide, 600 grit o clean debris from SS with acetone on Q tip until tip is clean o turn on vacuum for spin coater and position slide. Make sure slide is securely held o pour PI2525 from small bottle in center of SS, being careful not to introduce bubbles, let sit ~ 1 minute to partially spread out o spin on KW4A timer 1: 18 sec, 2:00 on dial timer 2: 50 sec, 3:00 on dial (this gives 4 um thick polyimide) o place slide+gelpak+stainless steel on hotplate at #3 for 2 minutes. SS will curl up and release from gel pak. Pull SS off of gelpak with tweezers, and remove gelpak from hotplate so it doesn't burn. Polyimide will still be tacky, so don't stick anything on it. o Place SS directly on hotplate (polyimide side up). To ensure uniform heating, loosely place glass slides at edge of SS to hold in contact with hot plate surface. Make sure hotplate surface is clean or SS will stick. Heat for 30 minutes on hotplate at #6 to cure polyimide. Longer might be better? (This is hot enough to burn/ignite paper so be careful). _____________________ etching ____________________ polyimide is easily cut with the laser on green- could coat both sides with polyimide if desired o attach SS to microscope slide with tape, or use gelpak o sand backside of SS with 600 grit silicon carbide o clean with acetone in Q tip o coat with red enamel spray paint under fume hood o cure 10 minutes on hotplate at #5, paint should be dry to touch (put beaker on top -open side down- to prevent air condx from cooling) o cut pattern on laser machine using low power setting, about 500, blast just paint, not S.S. 50 um wide green works well o put S.S. in small beaker/bottle with ferric chloride, agitate gently, check every 5 minutes- pull out with plastic tweezers, rinse in tap water. At room temperature, 50 um line was completely etched in 10 minutes, 50 um square was half etched in 10 minutes. Ferric chloride does not seem to affect polyimide.