Printed Wiring Boards Flexible

MIL-P-50884, Printed Wiring Board, Flexible or Rigid-Flex, General Specification for ... 

Manufacture of Printed Wiring Boards. Printed wiring boards, or printed circuit boards, are usually thin flat panels than contain one or multiple layers of thin copper patterns that interconnect the various electronic components (e.g. integrated circuit chips, connectors, resistors) that are attached to the boards. These panels are present in almost every consumer electronic product and automobile sold today. The various photopolymer products used to manufacture the printed wiring boards include film resists, electroless plating resists (23), liquid resists, electrodeposited resists (24), solder masks (25), laser exposed photoresists (26), flexible photoimageable permanent coatings (27) and polyimide interlayer insulator films (28). Another new use of photopolymer chemistry is the selective formation of conductive patterns in polymers (29). 

Electrochemistry is a central theme in the interconnection of chips and other microelectronic components. The manufacture of printed wiring boards, such as single-layer, multilayer, or flexible boards, involves electroplating of the conductor that forms the electrical paths. The corrosion of these paths and the interfacial stability of the conductor-polymer composites that determine the reliability of these interconnections are electrochemical problems. 

Besides this prime role of attachment, electrically conductive adhesives are widely used to form electrical contacts between components and the printed-wiring board or other interconnect substrate, such as thin-film or thick-film ceramic substrates or flexible cable. For this function, adhesives serve as low-cost alternates to wire, solder, and other metallurgical connections. 

Polyurethane adhesives are used primarily in the assembly of printed-wiring boards to attach large components such as capacitors, magnetics, heat sinks, and connectors. Their key benefits include flexibility, absorption of stresses, vibration damping, and thermal transfer. Being thermoplastic, polyurethanes are also easier to rework than epoxies. 

The number of equivalents of the polyol is 0.58, so the amount of the isocyanate required to react in a 1 1 ratio will be 111 grams. The more flexible polyurethanes used in printed-wiring board applications generally employ polyols that have lower hydroxyl contents. 

PEI resins have been used in a variety of applications such as electrical connectors, internal computer parts, printed-circuit boards, flexible circuits, optical fiber connectors, fire helmets, large appliances, aircraft interiors, trays, microwave cookware, reflectors, motor parts, gears, pumps, lubrication systems, wire coating, industrial applications, bearings, small appliances, films, and fibers. Polyetherimides are used in a wide range of applications. A few of the key markets for PEI resins and some of the benefits they bring to the application are summarized below. 

IPC-6202, IPC/JPCA Performance Guide Manual for Single- and Double-Sided Flexible Printed Wiring Boards ... 

JIS-C 5016 Test methods for flexible printed wiring boards... 

JIS-C 5017 Flexible printed wiring boards, single-sided and donble-sided... 

MIL-P-50884 Military Specification for Printed Wiring, Flexible, and Rigid Flex MIL-PRF-55110 Performance Specification, Printed Wiring Boards, Rigid General Specification... 

Uses Binder, film-former in paints (printed circuit board coatings, coil, container, corrosion protection, marine, metal, plastics, primers, sealers, tarp, wire enamels, wood varnishes, barrier primers), printing inks (gravure, flexo, screen printing), primers (adhesion promotion/corrosion protection), heat-sealable lacquers, two-pack paints, resinous/polymeric food-contact coatings, reactive resin in two-pack systems, e.g., crosslinked with melamine/phenolic resins Features Forms flexible, odorless, tasteless films thru solv. evaporation ... 

The first application of polyimides was for wire enamel. Applications for polyimides include bearings for appliances and aircraft, seals, and gaskets. Film versions are used in flexible wiring and electric motor insulation. Printed circuit boards are also fabricated with polyimides/ ... 

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