Molded three-dimensional circuit boards

Wolf, M. Injection Molding Three-Dimensional Circuit Boards. Kunststoffe, pp. 20-22, Feb. 1989. 

The manufacture of a three-dimensional circuit device from a molded plastic such as the demonstration part shown in Figure 1 differs from the traditional printed circuit board. Different imaging techniques are required due to the three-dimensional features of the devices. In addition, the metal comprising the traces on the surface of the substrate are now deposited rather than formed from the laminated copper foil. 

This chapter presents an overview of performance plastic polymers in commercial planar and 3-dimensional circuit board products, and describes in detail one approach (two-shot molding) developed as an integrated 3-D circuit manufacturing technology. The distinctions between conventional planar (2-dimensional) circuitry, based on thermoset laminates and "subtractive etching processes, and the enhanced design flexibility afforded by expanded interconnection capacity in three axes are discussed. Specific examples of 3-dimensional interconnect protoypes and products are described and pictured. 

Newer resins include polysulfone, polyethersulfone, polyetherimide, and polyetherketone. Some of these newer materials are high temperature thermoplastic, not thermoset, resins. They are being promoted for the design of injection-molded printed circuit boards in three-dimensional shapes for functional appHcations as an alternative to standard flat printed circuit boards. Only semiadditive or fully additive processing can be used with these devices. 

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