Dimensional stability of stripline materials

A pre-etch thermal shock treatment effectively stabilized ⅛″ stripline boards of irradiated polyethylene clad with 1 oz/sq ft copper. No evaluations have been completed regarding the effect of this process on other thicknesses or dielectrics. However, it is expected that the experimental procedure used for determining the proper treating cycle may be applicable to all thermoplastic stripline boards. Such processing would add to the cost of a finished microwave circuit, but when balanced against the higher price and weight of reinforced materials and potential failure of unstable circuits, the economics of a stabilizing treatment prove inviting.