Lucent Technologies Inc.

Carl J Tiegelmann

Chen-chieh Lin

Jae Hong Choi

William Mitchel Gibbs

A substantially warp-free laminate polymeric film structure is obtained by a fabrication process in which the individual layers of polymeric film that are to be laminated together to form a card or similar structure are selected such that the mechanical properties of one layer or pair of layers are offset by those of another layer or layer pair wherein each polymeric film layer is bonded to its adjacent polymeric film layers by adhesive layers wherein the adhesive layers have a tack point temperature that is within 10.degree. C. of the glass transition temperature of said polymeric film layers. The properties of the layers which may be subject to this consideration include, for example, the layer thickness, tensile strength, elongation factor, shrinkage rate, and machine processing direction. In an illustrative three-layer substrate embodiment of the present invention, the tensile strength, elongation factor, and shrinkage rate of the outer film layers of the substrate are the same, with the outer layers having a higher tensile strength value than the inner layer tensile strength. The orientation of the film's processing and machine direction and the orientation of the coil set of the film are also considered in arriving at a matched layer set.

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Little Rock, AR, United States of America

Carl J Tiegelmann