Thermal Effects on PCB Laminate Material Dielectric Constant and Dissipation Factor


Values for printed circuit board (PCB) laminate dielectric constant (Dk) and dissipation factor (Df) used in circuit design and signal integrity (SI) modeling are typically those presented on laminate maker datasheets. In most cases, these values are derived from measurements on samples which have not been exposed to thermal stresses representative of the printed circuit board (PCB) assembly process. This paper discusses the changes in Dk and Df values for a variety of laminate materials following simulated assembly thermal exposure of test vehicles to six SMT cycles at 260°C (Pb-free) or 225°C (SnPb eutectic). An additional concern arises around an effect of operating temperatures upon the effective Dk and Df of PCB materials. Due to thermal radiation from active IC devices, power supplies, etc., the operating temperature of PCBs within a network equipment chassis is typically higher than the 23-25°C value at which Dk and Df are measured and reported. This paper also describes the changes in Dk and Df observed when the test samples were measured at temperatures of 50°C and 75°C.

Meeting Name

IPC APEX Expo Technical Conference (2010: Apr. 6-9, Las Vegas, NV)


Electrical and Computer Engineering

Research Center/Lab(s)

Electromagnetic Compatibility (EMC) Laboratory

Keywords and Phrases

Circuit Designs; Data Sheets; Dissipation Factors; Laminate Materials; Network Equipment; Operating Temperature; Pb-Free; Power Supply; Printed Circuit Board Assembly; Signal Integrity; Test Samples; Test Vehicle; Thermal Exposure; Electric Power Supplies To Apparatus; Exhibitions; Lead; Organic Pollutants; Temperature; Printed Circuit Boards

International Standard Book Number (ISBN)


Document Type

Article - Conference proceedings

Document Version


File Type





© 2010 IPC (Organization), All rights reserved.

Publication Date

01 Apr 2010

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