Evaluation of Transmission Characteristic and Complex Permittivity on Relative Humidity for Flexible Printed Circuit Board in Microwave Band

Akihisa TSUCHIYA  Hideaki SUGAMA  Masami SAKURAI  Naomi HIDAKA  Osamu HASHIMOTO 

Publication
C - Abstracts of IEICE TRANSACTIONS on Electronics (Japanese Edition)  Vol.J93-C  No.6  pp.189-194
Publication Date: 2010/06/01
Online ISSN: 1881-0217
Print ISSN: 1345-2827
Type of Manuscript: PAPER
Category: 
Keyword: 
flexible printed circuit board,  complex permittivity,  humidity,  microwave, 

Full Text(in Japanese): PDF(407.5KB)

Summary: 
At the frequency range from 1 GHz to 10 GHz, complex permittivity of the Polyimide film (PI) and the Liquid crystalline polymer film (LCP) used for Flexible Printed Circuit Board (FPC) in relative humidity and drying condition are measured. As a result, real part of complex permittivity of the PI film in 25 and 60%RH increased by 10% as compared with drying condition. Dielectric loss factor of the PI film in 25 and 60%RH was 3 times at 1 GHz and 6 times at 10 GHz larger than drying condition. On the other hand, the complex permittivity of the LCP film in 25 and 60%RH was constant with drying condition. Compared with PI films with different moisture absorption, PI film with 1.4% of moisture absorption is 2 times larger than with 1.1% of moisture absorption. We reavel the influence of relative humidity on dielectric loss of microstrip line fabricated with each PI films.