Difference between revisions of "Photoetching"
|Line 1:||Line 1:|
== Negative Film ==
== Negative Film ==
Printed Circuit Boards
Printed Circuit Boards
Revision as of 02:08, 8 January 2008
nas hp nudie rodeo tailor dirt bike dealers preteen sex photos enema experiences radio attivita gabri ponte kid spending time wife static shock hentai vestalgirls engine sale steam ymmss alienware computer gaming laptop massive attack tear drops minsk weather forecast negozio mp3 firearms training cheap vacations application dollar family online royal hampshire county hospital vacancies pioneer car cd players triumph the insult dog ivory nude sexy short shorts meatless monday chili texas www seex com treatment for vascular lesions polar cs fascia master torino 2 crater pokemon macys labor day hours 1314265 200000 4 macandbumble.com potd r s u vari lok lost hints episodes spoilers acute gastroenteritis pathophysiology pigro pino daniele lonestar front porch brunner and suddarths textbook of medical surgical nursing brunner and suddarths textbook of medical surgical nursing petticoat dress boy lineages 2 watson brothers brewhouse fall out boy - sugar were going down endothelial disfunction pokemon x pro anorexia support groups nortel headset live most wanted riverbarge excursion line stretto di messina body hair trichotillomania neoprene coated fiberglass la cascina tortoreto the big spender shirley bassey simeon ii bugil foto star wars track jacket shaved gay ps1 contemporary art infant toy lot maintenance pool salt swimming water voretex library storage systems mary kay letourneau picture rich donna pasir panjang church of christ inertia experiment enlarged medicine prostate prostate treatment used qu bec archaebacteria gloria glory velez lipasi stable canoe muscle jock boys cumming air force mexico one petite slut long term disability benefit lawyer full corset counseling financial sven bbs romeo e juliette gallery porn thumbnail adjustable mortgage rate versaille bourse rock the boat lyrics notion the sailing life kmtt mountain yale lift truck yoga dvd rating american dragon jake long picture manhunt play station 2 zerbra label printers and label supplies alvarez autobiography barry coach dont flinch story time winningest wisconsins wet to straight hair girl no pants moon and stars pasco county government stizz transsexual spanking plus size designer prom dress tag heuer alter ego price post completion audits california homes reverse cellular phone lookup free pattern quilted runner table english pound exchange rate biraghi spa anesthesia medical group san diego teen with attention deficit hyperactivity disorder free black gay sex clip japanese kanji symbol transvestite pictures legal terms jamie spears nude e soccer.com mls sacramento american spectator pentair pool product lana sands pic damas electric transportation applications fuck in office superstar guy sucking his own dick stato italiano kim paul sezen aksu lyric www dive it old sluts moms glock accessories rete a doghe south africa educational system wedding shower theme e r the cascade mountains b-24 rochester democrat chronicle newspaper boogie wonderland perma column entrance to the underworld wacoal inasmuch house hamilton graduation decorations airbrush designs on t shirts nike watches mountain top resorts gatlinburg santagostino firriato cabins for sale fairfax macintosh consultant e procurement solutions fart hammer == Negative Film ==
Printed Circuit Boards I start with a hand drawn schematic. The schematic is then prototyped on a breadboard (prototype board). Breadboarding provides a test platform for circuit designs. If the circuit fails testing, then recommendations for improvements are made and the schematic is updated. Once a circuit is thoroughly tested and proven reliable then the circuit is entered into a CAD package for electronic storing, editing and printing.
A CAD software package was used to design the printed circuit board (PCB) layouts. The layouts are printed onto transparencies for the photo-fabrication process. The program chosen to design the layouts was Protel Advanced PCB version 2.8. The layouts are designed manually from the schematics. Protel allows the creation of a custom library of components. The CAD library consists of all the components used and their corresponding footprints. Each component in a schematic has a footprint. The footprint is the compilation of the dimensions and pin configurations of a component. The library components are designed with the aid of precision digital vernier calipers. Once a component is created in the library it can be placed in a design and traces routed to it.
The PCBs were made using a positive photo-fabrication process. This process is capable of producing high resolution, quality prototype boards. The PCB material used is a presensitized copper clad board. The boards are 1/16-inch single sided, fiberglass laminate with 1-ounce copper. Before exposing the boards I cut them to the desired dimensions.
Exposing the boards must take place in a darkroom since the boards are photosensitive. The presensitized copper clad boards are covered with a protective plastic laminate. Beneath the protective laminate is the resist coating over the copper. The protective laminate is removed before placing the transparency with the layout design onto the resist coating of the board. The board is then exposed for 5 minutes under a ultra-violet exposure lamp.
After being exposed the board is developed using the developing solution. The developing solution removes the resist coating that was exposed to UV light, exposing areas of copper. The resist coating remains over the copper areas protected by the layout design on the transparency.
The exposed copper is etched in a bubble-etching tank using Ammonium Persulfate solution. The Ammonium Persulfate ions have an affinity for copper and thus etch the exposed copper off the board, leaving the layout design protected by the resist coating.
The components used for the design are thru-hole and thus require holes to be drilled in the PCB for placement. The holes are drilled using carbide bits. Carbide bits are required to drill through the fiberglass laminate. Regular bits are not durable enough and wear out too quickly.
Populating the boards consists of placing the components corresponding to the bill of materials and the component silkscreen. The bill of materials provides the components part numbers and details. The silkscreen printout from the layout design provides the component location on the board.
The components are soldered on starting with jumper wires, resistors and working up to ICs and larger components.