PWB Fabrication-Ch16

PWB Fabrication-Ch16 - PWB Fabrication(Ch 16 Material...

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PWB Fabrication (Ch 16) Material, design and process for conventional laminated printed wiring boards
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PWB Fabrication (Material) Desirable Properties High Strength Nonconductive Non-burning Low Warpage Substrate (Base) Portion of the Circuit Board Purpose : Mechanically support and affix components, dissipate heat. •FR-4 board: A composite material made of multiple plies of epoxy and glass fiber or cloth as filler •Metal Core board: PWB with metal base used in high heat or high power dissipation •Earliest of PWB were made of phenolic and paper (not compatible with plated through-holes, therefore double-sided not optimal)
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PWB Fabrication (Material) Desirable Properties High Conductivity Light weight Strong bond to substrate Conductive Portion of the Circuit Board Purpose : Electrically connect components, provide power. •Copper (sometimes plated) is most commonly used •Conductive polymers (silver shavings embedded in plastic) •Typically 35μm thick •Copper foil laminated to substrate
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SMOBC (Solder Mask over Bare Copper) Main Purpose : To keep solder on copper pads (prevent solder bridges) and to form exact edges for contact points. Also, increases corrosion and flammability resistance and applied for aesthetic reasons. A plastic coating, typically either Blue or Green PWB Fabrication (Material) Desirable Properties Non-Conductive (Dielectric) Resistive to heat Repels solder Ink for lettering (inspection aid)
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PWB Fabrication (Design) Computer aided design (CAD) systems are used
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  • Fall '07
  • PERKS
  • Semiconductor device fabrication, Printed circuit board, Electron beam lithography, PWB Fabrication, removes unexposed resist

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PWB Fabrication-Ch16 - PWB Fabrication(Ch 16 Material...

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