Real-Time Shear Strength Monitoring in Wire Bonding
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Solution Overview
Problem
Existing methods for determining the shear strength of bonded free air balls in wire bonding processes are inefficient, requiring offline destructive tests that are time-consuming and costly.
Innovation Solution
A method to determine the shear strength of bonded free air balls in real-time on a wire bonding machine by monitoring wire bonding process signals during a controlled movement of the wire bonding tool, allowing for continuous operation and automatic adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If offline destructive tests are used to measure shear strength, then measurement accuracy is improved, but productivity is reduced and time is lost
Solution Approach 1:
The patent replaces the mechanical offline destructive testing system with an in-line electrical measurement system. Instead of physically shearing the ball and measuring force offline, the system uses electrical signals during the bonding process to determine shear strength, eliminating the need for separate mechanical testing equipment and operations.
Solution Approach 2:
The patent introduces electrical signals as an intermediary to indirectly measure shear strength. Rather than directly measuring the mechanical shear strength through destructive testing, the system uses electrical parameters (current, voltage, impedance) during the bonding process as intermediaries to infer shear strength, enabling non-destructive in-line measurement.
2Measurement precision
If offline destructive tests are used to measure shear strength, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The patent enables continuous measurement of shear strength during the wire bonding process without interruption. The electrical signals are monitored continuously throughout the bonding operation, allowing shear strength determination to occur simultaneously with production activities rather than requiring separate offline testing time.
Solution Approach 2:
The patent performs shear strength determination as a preliminary action during the bonding process itself. By measuring shear strength in-line during bonding, the system identifies potential issues before they affect production quality, eliminating the need for subsequent offline testing and rework time.
3Productivity
If in-line monitoring is implemented, then productivity is improved, but device complexity increases
Solution Approach 1:
The patent makes the wire bonding machine multi-functional by enabling it to perform both the bonding operation and shear strength measurement functions. The same machine hardware that performs bonding also monitors electrical signals to determine shear strength, eliminating the need for separate dedicated testing equipment and reducing overall system complexity.
Solution Approach 2:
The wire bonding machine performs self-diagnosis and self-measurement of shear strength through its own built-in electrical signal monitoring capabilities. The system uses its existing sensors and control systems to automatically determine shear strength without requiring external testing equipment or additional measurement devices.
Data Source
AI summary
A method of determining a shear strength of a bonded free air ball on a wire bonding machine is provided. The method includes the steps of: (a) providing a free air ball at a working end of a wire bonding tool; (b) bonding the free air ball to a bonding location of a workpiece; (c) moving the wire bonding tool, while in contact with the bonded free air ball, in a direction along the bonding location; (d) monitoring wire bonding process signals during step (c); and (e) determining a shear strength using the wire bonding process signals monitored in step (d).