Evaluation Technique for Complex Permittivity of Mid-Loss Underfill Materials by a Cut-Off Circular Waveguide Method in Millimeter Wave Bands

Takashi SHIMIZU  Yoshinori KOGAMI  

IEICE TRANSACTIONS on Electronics   Vol.E97-C    No.10    pp.972-975
Publication Date: 2014/10/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E97.C.972
Type of Manuscript: BRIEF PAPER
complex permittivity,  dielectric,  underfill material,  cut-off circular waveguide method,  millimeter wave,  

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Underfill materials are used in a packaging of millimeter wave IC. However, there are few reports for dielectric properties of underfill materials in millimeter wave region. A cut-off circular waveguide method is one of a powerful technique to evaluate precisely complex permittivity in millimeter wave region. This method may be useful not only for low-loss materials, but also for mid-loss ones with loss tangent of 10-2 order. In this paper, an evaluation technique based on the cut-off circular waveguide method is presented to measure mid-loss underfill materials. As a result, the relative permittivity εr and the loss tangent tanδ are in the range of 2.8∼3.4 and (1.0∼1.6)×10-2, respectively. Also, the measurement precision is 2.3% for εr ≅ 3 and 40% for tanδ ≅ 10-2.