Wire Bonder Gas Diffuser for Copper Wire Hardness Control
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Solution Overview
Problem
The high hardness of copper wire free air balls during wire bonding increases the likelihood of damage to semiconductor device bond pads and circuit board patterns, leading to defects and cracking, especially in low-dielectric constant semiconductor devices.
Innovation Solution
A wire bonder equipped with a gas diffuser that diffuses a heated gas to the conductive wire, reducing the hardness of the free air ball and improving bondability by maintaining the free air ball at a temperature of 25° C.-300° C., thereby avoiding damage to bond pads and enhancing the bonding process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copper wire is used to replace gold wire, then cost is reduced, but hardness of free air ball increases causing damage to bond pad
Solution Approach 1:
The patent applies parameter changes by heating the copper wire free air ball to temperatures between 25°C and 300°C before bonding. This thermal parameter change reduces the hardness of the copper wire FAB, making it softer and less likely to damage the bond pad during the bonding process, while still maintaining the cost advantage of using copper wire instead of gold wire.
2Strength
If heated gas is applied to reduce wire hardness, then bondability improves, but excessive heating may damage circuit board or semiconductor die
Solution Approach 1:
The patent applies preliminary action by heating the copper wire free air ball to a controlled temperature range (25°C-300°C) before the actual bonding operation. This pre-heating softens the wire FAB in advance, improving bondability, while the temperature is carefully controlled to prevent thermal damage to the circuit board or semiconductor die during subsequent bonding steps.
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 solution effectively reduces the hardness of copper wire free air balls, minimizing damage to semiconductor devices and improving bondability, as evidenced by increased ball shear and stitch pull forces with temperature variations, while avoiding excessive heating that could harm the circuit board or semiconductor die.
Implementation Method 1
A gas diffuser is positioned beside the capillary to diffuse a heated gas to the distal end of the wire... diffusing a heated gas to a conductive wire positioned at a lower end of a capillary... reduces the hardness of the free air ball
Implementation Method 2
provides an electric flame to a distal end of the conductive wire to create a free air ball
Data Source
AI summary
A wire bonder has a capillary through which a wire passes. A discharge tip is positioned near a bottom section of the capillary and provides a flame to a distal end of the wire. A gas diffuser is positioned beside the capillary to diffuse a heated gas to the distal end of the wire.