itmeThermal Analysis of Starch for Realizing
Embedded Channel in Low Temperature CoFired Ceramic Substrate
Eszter Horváth, Attila Géczy, and Gábor Harsányi
Department of Electronics Technology, Budapest University of Technology and Economics,
H-1111 Budapest, Goldmann Gy. t. 3, Hungary
horvathe@ett.bme.hu
Topic: A
Presentation: P
Summary: Multi-layer lamination with sacrificial volume material (SVM) was used to support
the embedded structures of the low temperature co-fired ceramics (LTCC) during lamination and
sintering. As a consequence of burnout, the increased fraction of evolving gases from SVM
requires an adequate adaptation of the firing process to provide a residue-free burnout without
damaging the structure. Using thermal analysis the intensity of the evaporating gases was
determined during co-firing, thus the modification of the heating profile could be done with these
experimental results. Thermal and thermoxidative degradation for starch by different methods
has been studied. Activation energy and pre-exponential constant of starch was evaluated by
applying Arrhenius kinetic model to the resulting data. The study of SVMs degradation kinetics
shows that its degradation could be controlled by changing the heating rate. Based on these
results, embedded structures in a multi-layer LTCC platform were realized by controlling SVM
burnout with a modified heating profile.
Keywords: Key words: LTCC, microchannel, SVM, thermal analysis.
Motivation
The LTCC technology offers good realization possibilities through the implement of
electrical, mechanical and fluidic elements on one substrate [1,2]. The application of LTCC for a
microsystem with three-dimensional forms needs the adaptation of some technology steps. Both
the parameter values and the technological sequence of the standard LTCC process must be
varied. Deformation and sag of the channel during lamination can be avoid by filling the cavity
with fugitive material. Additionally as a consequence of burnout, the increased fraction of
evolving gases from SVM requires an adequate adaptation of the firing process to provide a
residue-free burnout without damaging the structure. The application as SVM makes important
to study the thermal and thermoxidative degradation behavior and the kinetic parameters of
starch by different techniques.
Results
Thermal degradation under inert atmosphere and thermoxidative degradation under air
atmosphere for starch by Flynn-Wall-Ozawa and Coats–Redfern methods using
thermogravimetric analysis at 10, 20, 30, 40 and 50% mass losses has been studied (Fig. 1 and
Fig. 2). Activation energy and pre-exponential constant of starch was evaluated by applying
Arrhenius kinetic model to the resulting data.
-2.26E-04 -2.24E-04 -2.22E-04 -2.20E-04 -2.18E-04 -2.16E-04
-12.4
-12.6
ln(F(α)/T^2)
-12.8
-13
-13.2
y = 197839x + 30.465
-13.4
-13.6
F(α)=-ln(1-α)
Experimental
Fit
-13.8
-14
-14.2
-14.4
-1/RT
Fig. 1: Result of Coats-Redfern method in N2
atmosphere at the heating rate of 10°C/min.
Fig. 2: Flynn-Wall-Ozawa plots of lnβ against
1/T in nitrogen.
Based on these results, it is proposed that the fabrication of embedded structures in a multilayer LTCC platform could be achieved by controlling SVM burnout with a modified heating
profile, which can ensure complete burnout without affecting damage of LTCC structures. Using
this approach, fabrication of embedded channels with dimensions of 30 mm×1 mm×0.50 mm in
LTCC substrate is demonstrated.
References
[1]
[2]
Khanna PK, Hornbostel B, Burgard M, Schafer W, Dorner J. Studies on threedimensional
moulding, bonding and assembling of low-temperature-cofired ceramics for MEMS and MST
applications. Mater Chem Phys, pp. 89:72–9, 2005.
Jones WK, Liu Y, Wang P, Zampino M. Chemical structural and mechanical properties of LTCC
tapes. Int J Microcirc Electron Packaging, pp. 23(4):469–73, 2000.