Bond Failure Mode Classification via Force Displacement Analysis
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Solution Overview
Problem
Existing methods cannot accurately distinguish between ductile and brittle failure modes in bond strength tests of semiconductor devices, making it difficult to determine the quality of the bond between a substrate and electrical connections, such as solder bumps or ball grid arrays.
Innovation Solution
The method involves analyzing force-displacement characteristics, including energy absorption after the peak applied force, and using variable speed testing to differentiate between ductile and brittle failure modes by processing digital signals from force and displacement measurements to determine the mode of failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If peak force measurement alone is used to assess bond strength, then the measurement process is simple, but the ability to distinguish between ductile and brittle failure modes is insufficient
Solution Approach 1:
The patent transitions from one-dimensional peak force measurement to two-dimensional force-displacement curve analysis. By incorporating displacement data alongside force measurements, the system captures the complete mechanical response during testing, enabling differentiation between ductile and brittle failure modes through the shape and characteristics of the force-displacement curve rather than relying solely on peak force magnitude.
Solution Approach 2:
The system implements automated analysis where the force-displacement data is processed through algorithms that provide feedback on failure mode classification. The computer automatically compares the measured curve characteristics against known patterns for ductile and brittle failures, providing real-time feedback to classify the failure mode without requiring manual interpretation by the operator.
2Productivity
If manual inspection of substrate after test is performed to determine failure mode, then equipment complexity is low, but productivity and automation are reduced
Solution Approach 1:
The system enables self-service automated classification by embedding the analysis capability within the testing apparatus itself. The computer automatically processes the force-displacement data, applies classification algorithms, and determines the failure mode without requiring external manual inspection. This integrates the analytical function directly into the testing system, allowing continuous automated operation.
Solution Approach 2:
The patent replaces the manual visual inspection process with an automated computational analysis system. Instead of relying on operators to physically examine substrates under microscopes or with naked eyes, the system uses computer-based algorithms to analyze the mechanical response data, substituting human sensory and cognitive processes with automated computational methods.
3Measurement precision
If variable speed testing is implemented to differentiate failure modes, then measurement accuracy improves, but testing time and process complexity increase
Solution Approach 1:
The system employs dynamic testing by varying the crosshead speed during the test process. Rather than using a single constant speed, the testing machine adjusts the loading rate dynamically based on the detected failure mode characteristics. This allows optimization of the testing process by adapting the speed to the specific material response being measured, improving discrimination between ductile and brittle behaviors.
Data Source
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AI summary
A method and apparatus for determining a mode of failure of a bond between an electrically conductive ball deposit and a substrate when breaking the ball deposit off of the substrate. The method and apparatus utilize tool force and displacement values to plot a force/displacement curve. The force/displacement curve is used to calculate the energy necessary to break the ball deposit off of the substrate. The energy value of a portion of a force/displacement curve is selected by reference to a peak force. In one preferred embodiment, this energy value is compared with a predetermined reference energy value to indicate a mode of failure. The peak force is preferably the maximum peak force, hi the preferred embodiment, the method and apparatus distinguish between a ductile failure mode and a brittle failure mode.