How advanced low coefficient of thermal expansion (CTE) laminates and prepregs can improve the reliability of printed circuit boards (PCBs)

Abstract

This paper details the impact of “Coefficient of Thermal Expansion” (CTE) imbalances caused by the different materials used in a Printed Circuit Board (PCB). It will also provide guidance as to how the PCB manufacturing process can be modified to accommodate the new requirements from PCB fabricators, assemblers and OEMs for high dimensional consistency of the laminate and prepreg to improve manufacturing yields in bare PCB fabrication, in assembly and during the life‐cycle of the electronic device in the field.The paper also explains the risks associated with metal migration and cathodic/anodic filaments (CAF) in PCBs, the impact of a lower CTE and a lower dielectric constant (Dk), as well as the need to minimise the differences of CTE between the PCB laminate and the package/chip in order to better manage the higher stress incurred by the use of lead‐free soldering materials. New materials are discussed which are processable in standard PCB fabrication lines, and which can accommodate the needs engendered by halogen‐free resin systems.

Citation

Weinhold, M. and Yen, G. (2003), "How advanced low coefficient of thermal expansion (CTE) laminates and prepregs can improve the reliability of printed circuit boards (PCBs)", Circuit World, Vol. 29 No. 1, pp. 24-31. https://doi.org/10.1108/03056120310445907