Experimental and Numerical Thermal Analysis for Advanced Flip Chip Thermo-Compression Bonding via CMOS Microsensor Arrays and Finite Element Modelling
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Date
2017-10-03
Authors
Athia, Depayne
Journal Title
Journal ISSN
Volume Title
Publisher
University of Waterloo
Abstract
Thermo-compression bonding (TCB) relies on uniform thermal distribution during
microelectronic packaging processes to ensure reliable interconnects are formed. During
any TCB processes, the thermal application must uniformly distribute heat in order to produce
robust, thoroughly bonded packages without being damaged due to thermo-mechanical
effects. To better control and develop TCB processes, further insight through thermal
analysis is required. Due to the form factors and complexity involved in TCB, it is difficult
to accurately extract viable information such as temperature variation, lateral and vertical
gradients, or interfacial bonding temperatures.
To extract real time in-situ temperature and force signals, a microsensor array was
used to observe any thermo-mechanical features recorded during emulated TCB processes.
Algorithms were developed to post-process the signals and produce quantifiable
data. Finite element models were developed to verify the experimental thermal responses
and subsequently post-analyze the numerical results. Models formed through hybridized
contact resistance layers as well as surface contact models are also discussed.
Several features were identified and quantified: maximum heating rates, location
of maximum lateral thermal gradients, internal joint thermal distributions, knee-region
slope analysis and joint to joint thermal variation. The experimental responses in combination
with numerical analyses show evidence that thermal applications during TCB is
robust. Low thermal variation was found with respect to joint to joint temperatures. Chip
design was found to heavily influence cooling on the periphery edges of the bump array.
The sensor chip temperatures were to found to be about ≈ 6 °C lower than the extracted
bump temperatures, signifying the use of microsensor arrays could be developed as accurate
tools for thermal process control during TCB.
Description
Keywords
thermo-compression bonding, finite element analysis, flip chip, CMOS, RTD, microsensor, thermal contact resistance, thermal, thermal gradient, numerical analysis, Gold bumps