Compression Press Calibration for Uniform Flip-Chip Bonding Pressure
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Solution Overview
Problem
Current flip-chip bonding technologies face challenges with non-uniform compression forces, particularly affecting bumps at edges and corners, and varying functions with large pitch distances, leading to inefficient inter-chip bonding.
Innovation Solution
A method and system using a compression system with a first substrate and a second substrate, where the second substrate has spikes that form indentations in a test film, allowing for the determination of local pressures and adjustment of calibration parameters to achieve uniform pressure distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional compression bonding is used, then bonding process is simple, but pressure distribution is non-uniform causing edge and corner bumps to be over compressed
Solution Approach 1:
A test film is introduced as an intermediary layer between the first substrate and second substrate. This test film deforms under compression to create visible indentations that map the pressure distribution, allowing non-invasive measurement of contact pressure without interfering with the actual bonding process.
Solution Approach 2:
The pressure distribution is copied onto the test film as a pattern of indentations. By imaging these indentations, a visual copy of the pressure map is created, enabling analysis of pressure uniformity without directly measuring forces at each bump location.
2Strength
If compression force is increased to improve bonding, then bonding strength improves, but non-uniformity in pressure distribution worsens
Solution Approach 1:
The system uses imaging of test film indentations to provide feedback on pressure distribution. This feedback loop allows operators to adjust compression parameters (force, alignment, tilt) to achieve both sufficient bonding strength and uniform pressure distribution, preventing over-compression of edge bumps.
Solution Approach 2:
Calibration is performed before actual bonding using test substrates with test films. This preliminary action establishes the correct compression parameters and alignment that will produce uniform pressure distribution, ensuring optimal bonding conditions are set in advance.
3Ease of manufacture
If pitch between bumps is large (50 microns or greater), then manufacturing is easier, but compression forces exhibit varying function with oscillatory behavior
Solution Approach 1:
Direct mechanical measurement of forces at each bump location is replaced with an optical measurement system. The test film indentations are imaged and analyzed to determine pressure distribution, substituting complex mechanical force sensing with simpler optical imaging and analysis.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables high-resolution measurement and visualization of local and global pressure distributions, ensuring uniform compression forces for improved inter-chip bonding, enhancing performance in three-dimensional integration by increasing interconnectivity and reducing manufacturing failures.
Implementation Method 1
compressing the first substrate and the second substrate together with a force that causes the plurality of spikes to form a plurality of indentations in the test film
Implementation Method 2
generating an image of the plurality of indentations in the test film, wherein a plurality of light intensities in the image are representative of the plurality of local pressures
Data Source
AI summary
A method to aid in a calibration of a compression system includes mounting a first substrate in a press. The press has calibration parameters, and the first substrate has a test film on a first surface. The method includes mounting a second substrate in the press. The second substrate has spikes arranged in a spike pattern on a second surface. The method includes compressing the first substrate and the second substrate together with a force that causes the spikes to form indentations in the test film, separating the first substrate from the second substrate, determining local pressures applied by the spikes against the test film, and adjusting one or more calibration parameters of the press in response to the local pressures.