Capillary Bonding Apparatus for Even Wire Loops on Overhanging Dies
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Solution Overview
Problem
Existing wire-bonding techniques for overhanging semiconductor dies face challenges in forming even wire loops due to the need to stop and detect contact, which slows down the process and introduces accuracy issues from load variations caused by disturbances.
Innovation Solution
A bonding method and apparatus that detect the position and load of a capillary in association with each other, calculate the movement distance based on a load change point, and retract the capillary by this distance to form wire loops, eliminating the need to stop at contact and reducing the influence of vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the capillary stops moving to detect contact position, then the contact detection accuracy is improved, but the loop formation speed deteriorates
Solution Approach 1:
The system performs preliminary action by continuously detecting capillary position and load during movement, and pre-calculates the movement distance to the contact point before actual contact occurs. This allows the system to prepare the retraction amount in advance, eliminating the need to stop for detection and enabling continuous high-speed operation while maintaining accurate contact detection.
2Measurement precision
If the capillary stops to detect low load contact, then the contact position is accurately identified, but the overall bonding process time increases
Solution Approach 1:
The system maintains continuity of useful action by continuously moving the capillary toward the bonding position without interruption. The load sensor continuously monitors contact force during movement, and the control unit continuously calculates the movement distance, enabling the entire process to proceed without stopping, thus eliminating time loss while maintaining detection accuracy.
3Difficulty of detecting and measuring
If load detection is used to detect contact, then the contact position can be identified, but detection accuracy is reduced due to load variation from disturbances
Solution Approach 1:
The system applies feedback by continuously monitoring the relationship between capillary position and load, and using this feedback to dynamically calculate and adjust the movement distance. The control unit processes the correlated position and load data to identify the load change point, and uses this feedback information to determine the precise retraction distance, compensating for load variations and maintaining high detection accuracy.
4Productivity
If the capillary moves continuously without stopping, then the loop formation speed is improved, but the reference position for wire loops becomes unstable
Solution Approach 1:
The system performs preliminary calculation of the movement distance from the load change point to the bonding position before forming the wire loop. This pre-calculated distance is stored and used as a reference for the retraction amount, ensuring that even though the capillary moves continuously without stopping, the reference position for wire loop formation remains stable and consistent, resulting in even loops.
Data Source
AI summary
Provided is a bonding apparatus capable of forming even loops at high speed. According to a bonding apparatus 1, a capillary 5 is lowered to a bonding position to bond an initial ball 10 to a pad 104 on an overhanging die 100. Here, a position of the capillary 5 in a Z direction and a load detected by a load sensor 7 are detected and stored every predetermined time period. A load change point is detected by referring to the stored load and the stored position. By subtracting the bonding position from a load changing position of the capillary 5 at the load change point, a movement amount Z of the capillary 5 from the load changing position to the bonding position is calculated. After the capillary 5 is lifted by the movement amount Z, a wire loop is formed between the pad 104 and a lead 105.