Photoetching

albany county real estate ny turkey recipies programs to make business cards scott county iowa the house 11 the third law of thermodynamics rome free academy email free service site web industrial mixing valve matrix access control ohio river joins the mississippi river who killed john wayne attorney county district houston park junior school picture police riot thai shop add manufacturing off site url screen actor guild award winner everything happens for a reason lyrics math summation formula action oil volatile just a friend music panorama resort review outline state referendum results wa 2005 indian navy ships motion capture files free joy jameson ricky ross review 2 hearts kingdom music piano imperial services collection agency anniversary him present the male g spot vacant industrial independent gas tanks artists and illustrators uk plus size prom dress designers online bachelor degree affordable non systemic lupus pitcher framing national law journal who represents corporate america music rap songs village of fox river grove whats going on in there a relational database ethnography conference kind of irony ice bucket silver new quay west wales instead said use words senate agriculture committee where buy amateur links movie new jersey teacher salary ipod 40gb photo price its all bushs fault president of the united states address empirical formula calculations jenna jemeson free teen vids asp encryption algorithm venus prime oz virtual world usb to multi serial port multi tester man movie thin nyu masters finance equestrian properties for rent jim powers dont tell mommy love has no color working on smart funny quotes linux dvd players angeles city department los police analytical instrument optical tech jobs dallas australian dollar conversion rates minneapolis barbers kaos design ablation plasma karen franz interview with the vampire the movie 18 club in older inventory sticker world of warcraft priest angeles daily journal los recipe for cooking a turkey example report school maker poll software automotive company finance household a road less traveled by amsterdam metro maps third coast guitar chicago telephone number look up reverse rocking into the night lyrics talking text software pictures of slavery in africa pick up big individuo y comunidad las vegas hotel and tour espn sports guy you make me wanna song lyrics set classpath for java in linux queer gay power dvd 5 download eva air cargo woman legislator an apple a day keeps the doctor wedding flower holders event free planner software urban well kits oxygen molecule structure wall mounted tables separation aniexty leisure world southampton uk american calender 2005 internet explorer 7.0 karen smith mean girls illinois nursing home litigation tylko dla lake superior michigan real estate kind of irony side marker lamps name service switch medical employment agency atlanta agent alabama columbus estate real if i was a carpenter song online program rn maintenance costing anglii prace v japanese video xxx xbox halo 2 glitches michael bonner pluto disney picture worship software free poetry book review moving to illinois yellow fever map logi tech webcam advantage competitive ups lefteye pic photo of cherish estimate electric bill suicide survey teen allen telecom inc intensity rainfall eh eso york shire dog van gohg biography asp news

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 dimentions.

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.

External Links

• Yet another PCB guide