Photoetching

levers www volta it serghei besplatni ex yu midi bubba sparxxx cuffia piscina monitor 26 principe e socio m occhiali dolce renault grande espace soltanto tra amici punto 187 gs1 qqaaxx lampada da giardino inno corpo sciolto seconda prova 2004 or hacker killed berg nel cerchio western digital - hard disk wd 74gb tastiere musicali per computer boston red sox ticket lettori dvd-vcr foto di giardini fonetica live calze sexy hotel imperial djerba partitura pachelbel kavalier hotel vienna televisori samsung 32 pollici obbligazione tiscali puttanella casse jbl per pc www delonghi com torna il sereno eustace spartiti vasco senso klite maporama com classico mario bros times square snoopy tennis devilman story initiatives centro assistenza amstrad roma freddie mercury tribute www agritur it maxtor 120gb ata cuffie walkman terrario carboneria airone orari da roma fiumicino renault laguna grandtour dci smashing pumkins malattie tumorali telemundo51 obiettivi eos 350d hotel centro storico firenze blu express www miniclips congreso eucaristico ruggito tigre can i mpd psycho 1 il ritorno di lassie assicurazione ortisei incontri sex descrizione di strutture per anziani lingua lunga firestone vacanze offerta gem shop calendario di victoria calendari 2006 asus k8n-dl hooft, pieter cornelisz kabyle nupe pentium m 730 condizionatori fissi whirlpool drum magicolor 7300 telefonino alcatel agenzia matrimoniale ragazze latine era una notte buia e tempestosa... the best is yet to come flying shark palmari compaq pocket pc spartiti gen verde i promessi sposi alessandro manzoni multipla jtd serie speciale sound trak films mi sdoppio in 4 la marsigliese cucconi kernite fava abbigliamento cani colron toshiba sa50 filosofico giacca moto donna about her malcolm mclaren toghether definizione di colonialismo ladro damore ingrosso articolo regalo cd bombay fotocopiatrici canon ir 1600 creare sito web gratis adattatori joypad play station koda un univers obsesion mid www nikon jvc dr-mh30 nuove immagini da forza motorsport secret sorrow jaguar xjsc hotel aurelia and suites monitor tuner vip a jesolo orgy starblazers carts tasso di inflazione cappe per cucine donnenude nike 35 rosa dvd gorillaz peter evrard freddy fitness hp jetdirect 300x harman kardon on tour maliziose video canadese rilasciata iraq zuma srl archos 4 in 1 man i fill like a woman barra, eduardo de la- punjabi mc kodomo pianta friburgo te iubesc asa de mult olbia verona biglietti aerei dangelo f sobri notr destin giochi porno reali gratis la signora del fiume adidas calzature - ragazza villorba storie divertenti sul matrimonio getix www yugiohetc com s2emu 2 download cartoline calabria porto vintage porte e finestra xfx 6800 cervantes saavedra, miguel de- piano gospel wireless netgear tony tamaro zegar smierci lavello nike golf palline hotel reggio emilia racconti incestuosi in famiglia what if vila real (distretto) kusbdtii 1gb snow, sir charles percy facolta di infermieristica discipline devil may cry 3 ha un nuovo trailer haj belaid take my breack away dect gap brondi giugno 84 la bellissima estate mutua e previdenza - casse batterie olympus litio bennato mediterraneo finanziamento statali machina della grondaia il volo del calabrone remix testi furtado i go again pentium iv intel processori svetlana khorkina playboy sony dscw15 sirena ambulanza korn. deuce el sa sa sa video pe hex carta pirata esonero leva militare bar stools rex microonde tour robbie williams giacca antipioggia nilsen kurt l indiana snc

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 t 1000 hru-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