The general definition of anisotropy is variation in a given material property with respect to orientation. In the case of woven fiberglass composite laminates such as TLY-5A, Er anisotropy specifically refers to the differences in dielectric constant in the X and Y plane of the laminate compared with the Z axis. In printed circuit boards, the degree of anisotropy has relevance in cases where electric field lines are oriented in perpendicular to the Z axis.

This white paper describes the evaluation of Er in the X and Y planes of Y-5A material using samples from a thick test laminate, by means of the Bereskin Method. The results demonstrate that TLY-5A with woven fiberglass provides all the advantages of woven fiberglass laminates with a very low degree of anisotropy, making it a quality choice for applications requiring optimal low DF.