Moulded circuitry

Given that some basic technical problems can be overcome, metallic additives have an exciting future with the possibility of moulding the complex electrical and electronics circuits in electronics equipment, as are used now in automobiles, rather than using printed circuitry. While printed circuits go a long way, the next stage is to mould three-dimensional circuitry, and mixing metallic 

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Although it consumes only about 5-7% of plastics, the electrical and electronics market sector exercises large demands on additives, which will certainly grow in volume and value. Covering both consumer and industrial products, E and E involves housings and enclosures for all types of equipment and an increasing volume of moulded connectors and circuitry. Insulation and sheathing for wire and cable, with its own specific demands, can also be included. 

Vacuum infrastructure The evacuation of the vacuum bag is realized by vacuum pumps connected via tubes and hoses to intake valves in the vacuum set-up. The intakes can be positioned either in the vacuum bag, in which case the vacuum foil has to be perforated in order to provide a passage, or as part of circuitry integrated into the mould. For further distributing the airflow efficiently, it is usually necessary to install additional channels underneath the vacuum bag, e.g. by stacking up several narrow layers of breather fabric. 

The trend for miniaturisation and increasing complexity of circuitry has already seen the standard for contact spacing fall from 0-2 to 0 1 in and a further reduction to 0-05 in may take place. The plastics employed for connectors must be easily moulded in intricate moulding tools with thin sections and close tolerances. 

In electronics, polyimides are now extensively used in the form of self-standing films for flexible circuitry, deposited films for interlayer dielectrics, passivation and buffer coatings, moulding thermoplastic powders for PCBs, and adhesive pastes or tapes. The basic polyimide chemistry has been adapted to fulfill the specific requirements of these applications. A series of books provides complete information not only on the chemistry of polyimides but also on their utilization in electronics [4,23,24]. The following figures summarize the chemical formulae of the most important categories of polyimide precursors or precyclized polymers that are commonly used in electronics. 

These plastics are processable by injection moulding, blow moulding, extrusion and sheet forming and can be plated. Applications include electronic connectors, TV components, printed circuitry, projector lamp housings, and filter bowls. Produced in the USA, it is worthwhile monitoring the availability of polysulphones as applications are planned. 

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