IPC International, Inc. Effects of Moisture Content on Permittivity and Loss Tangent of Printed Circuit Board Materials PDWEB10-PCBMOIST

DESCRIPTION Printed circuit board laminate datasheets provide permittivity (dielectric constant, Dk) and loss tangent (dissipation factor, Df) values that are used for specification and board design. But past studies have shown that these properties vary with changes in the moisture content of the PCB laminate material. Major problems can arise when material substitutions are made using laminate datasheets as a guide, especially when the data is derived using dissimilar test conditions or methods. For example, initial impedance calculations on the basis of datasheet values may be acceptable, but actual board performance may be significantly different and may result in poorly functioning and unreliable boards. This webinar will discuss the results of an experimental study to establish whether the preconditioning steps outlined in the IPC-TM-650 2.5.5.9 (Permittivity and Loss Tangent, Parallel Plate, 1MHz to 1.5 GHz) test standard account for varying moisture contents in PCB laminate test coupons. The moisture content in a PCB material may vary because of material constituents, board design or handling, processing, shipping and end use conditions. Results also shed light on the dependence of dielectric values on moisture content and type of flame retardant used. Commercially available PCB materials sourced from two manufacturers were tested in this study. Materials were classified on the basis of flame retardant type (halogenated or halogen-free) and glass transition temperature. Extent of variation in the dielectric properties is discussed as a function of material constituents and moisture content. Types of materials that are most affected—and reasons behind the variation—are also reviewed. 59 minutes. Released 2010. This downloadable webinar includes synchronized audio and slides. It was presented by Bhanu Sood, CALCE.