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Probe for Measurement of In-Plane Dielectric Properties of Bulk

IP.com Disclosure Number: IPCOM000106131D
Original Publication Date: 1993-Sep-01
Included in the Prior Art Database: 2005-Mar-20
Document File: 4 page(s) / 117K

Publishing Venue

IBM

Related People

Edelstein, DC: AUTHOR

Abstract

A planar electric probe is disclosed which, when brought into contact with a planar dielectric surface (either of a bulk or thin-film sample), can be used to measure the surface conductivity and in-plane dielectric properties of the sample at frequencies from DC to ~10 GHz. It is useful, for example, for inexpensive and rapid assessment of various polymer thin film dielectric properties over a broad frequency range. The in-plane dielectric probe is depicted in Fig. 1 (plan-view and cross-section). It consists of the following: optimally-designed thin-film metal interdigitated comb capacitor (CC, described in detail below); two thin-film metal contact pads (CP) connected to the comb capacitor; fused silica substrate (SiO&sub2.) diced from 0.

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Probe for Measurement of In-Plane Dielectric Properties of Bulk

       A planar electric probe is disclosed which, when brought into
contact with a planar dielectric surface (either of a bulk or
thin-film sample), can be used to measure the surface conductivity
and in-plane dielectric properties of the sample at frequencies from
DC to ~10 GHz.  It is useful, for example, for inexpensive and
rapid assessment of various polymer thin film dielectric properties
over a broad frequency range.  The in-plane dielectric probe is
depicted in Fig. 1 (plan-view and cross-section).  It consists of the
following:  optimally-designed thin-film metal interdigitated comb
capacitor (CC, described in detail below); two thin-film metal
contact pads (CP) connected to the comb capacitor; fused silica
substrate (SiO&sub2.) diced from 0.025" thick wafer with
chemically-etched trench (TR); a printed-circuit board substrate (PC)
with two plated-through holes and contact pads (PTH); two wire-bond
connections (WB) from CP to PTH; a sub-miniature 50 &Omega.  coaxial
cable (CX) with signal line (SIG) and ground shield (GND) bonded to
reverse sides of PTH; strain-relief strap (SR); compliant rubber or
polymer pad (P) glued to back of PC; rigid shaft (SH) bonded to back
of pad through backing plate (BP); and one high-freqency SMA or 3.5
mm connector (SMA) attached to other end of CX.  A capacitance, LCR,
impedance analyzer, or network analyzer instrument is connected to
the SMA connector for the measurement.  Alternatively the backs of
the plated-through holes can be probed directly by a high-frequency
probe such as from Cascade Microelectronics, Inc.  The shaft S is
held in a moveable chuck which lowers the probe onto the sample with
a slight pressure so the probe rests flat on the sample surface.  At
this point the capacitance, conductivity, dissipation factor,
breakdown voltage, I-V characteristic, and any other electrical
measurements can be made with the appropriate meter.  The design of
the comb capac...