Printed circuit board process considerations

Statistical copolymerization of ethylene glycol and 1,4-butanediol with dimethyl ter-ephthalate results in products with improved crystallization and processing rates compared to poly(ethylene terephthalate). Polyarylates (trade names Ardel, Arylon, Durel), copolymers of bisphenol A with iso- and terephthalate units, combine the toughness, clarity, and proce-sibility of polycarbonate with the chemical and heat resistance of poly(ethylene terephthalate). The homopolymer containing only terephthalate units is crystalline, insoluble, sometimes infusible, and difficult to process. The more useful copolymers, containing both tere- and isophthalate units, are amorphous, clear, and easy to process. Polyarylates are used in automotive and appliance hardware and printed-circuit boards. Similar considerations in the copolymerization of iso- and terephthalates with 1,4-cyclohexanedimethanol or hexa-methylene diamine yield clear, amorphous, easy-to-process copolyesters or copolyamides,... 

The following are important design considerations regarding the assembly process for a through-hole printed circuit board products ... 

As far as the production of these samples is concerned, the outlay involved in the lasering, metallization, and component placement processes for MID components is comparable to that for the manufacture of other electronic parts such as printed-circuit boards. The costs incurred for preparing the plastic blanks as the MID bodies in real-part quality, by contrast, are considerably higher because an injection-molding tool is necessary. 

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