Method to evaluate the electrical performance of printed circuit board laminate materials

Abstract

Board materials are rapidly changing to meet the requirements for low cost, environmentally preferred, and data rate (3G) applications. Therefore, it is necessary to have electrical test and characterization methods that are quick, accurate, and able to be implemented during development, design, and manufacture. In order to meet these needs, a characterization method was developed based on RF resonator filter printed circuit structures. The method is repeatable, cost effective, and uses automated test equipment and procedures. The design of the filter structures is such that the sensitivity is capable of detecting critical RF attributes of the dielectric material and the printed circuit manufacturing process. The test procedure is capable of determining variation in dielectric constant, material loss, dielectric thickness, and layer-to-layer alignment. The results are given in terms relevant to circuit design applications - selectivity, bandwidth, and insertion loss. This paper discusses the electrical performance of printed circuit board dielectrics needed to meet today's requirements, the novel test method used to evaluate the dielectric and manufacturing process, and the data collected for materials such as FR4, environmentally preferred, and low Dk high performance laminates using the new test method.