Ball Bond Attachment Using Mechanical Scrubbing
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Solution Overview
Problem
Ultrasound-based wire bonding in semiconductor packages is not always stable and requires a long time to establish a sufficient electrical connection due to instability in bonding the ball formed at the end of the wire to the semiconductor die.
Innovation Solution
A scrubbing technique is employed instead of ultrasound, where a motor moves the bonding table with the semiconductor die relative to the capillary containing the wire, applying a lateral or circular motion to adhere the ball to the pad, with specific parameters like scrub force, amplitude, and cycle number adjusted based on wire diameter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ultrasound-based bonding is used to attach the ball to the pad, then the bonding process can be performed, but the bonding stability is poor and the bonding time is long
Solution Approach 1:
The patent replaces the ultrasound-based bonding mechanism with a mechanical scrubbing system. A motor drives a scrubbing element to mechanically scrub the ball against the pad surface, creating a reliable mechanical bond through friction and pressure rather than ultrasonic vibration. This substitution eliminates the instability and time delays associated with ultrasound bonding while achieving consistent, rapid attachment.
2Manufacturing precision
If traditional ultrasound method is used, then bonding can be achieved, but the bond shape regularity is poor and structural failures occur
Solution Approach 1:
The patent changes the bonding parameters by replacing ultrasonic vibration with controlled mechanical scrubbing. The scrubbing force, pressure, and motion characteristics are precisely controlled to produce uniform, regular bond shapes. This parameter change eliminates the irregular bonding and structural failures that occur with traditional ultrasound methods, achieving consistent and reliable bond morphology.
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
The scrubbing method results in a more stable, uniform, and quicker formation of ball bonds, reducing the likelihood of structural failures and improving the regularity of the bond shape compared to ultrasound-based methods.
Implementation Method 1
moving, using a motor, the support surface relative to the capillary tool to thereby bond the ball, without using ultrasound, to the pad
Implementation Method 2
applying a lateral or circular motion to adhere the ball to the pad
Data Source
AI summary
A method for forming a ball bond for an integrated circuit formed on a semiconductor die includes forming a ball at a first send of a conductive wire inserted in a capillary tool and lowering the capillary tool toward a pad on the semiconductor die positioned on a support surface. The method further includes moving, using a motor, the support surface relative to the capillary tool to thereby bond the ball, without using ultrasound, to the pad and then raising the capillary tool.