Ultrasonic Bonding Electrode Terminal Hollow Part Oxide Removal
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Solution Overview
Problem
Conventional solder bonding in power semiconductor devices is unreliable due to overheating, which remelts the solder and results in nonuniform bonding and complex manufacturing processes, while existing ultrasonic bonding techniques do not effectively remove oxide films from the center of the bonding surface, leading to unbonded areas and insufficient bonding strength.
Innovation Solution
Incorporating a penetrating hollow part in the electrode terminal surrounded by the bonding surface allows the oxide film to be pushed aside during ultrasonic bonding, ensuring a strong bond and enabling visual inspection of the bonded area through the hollow part.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If solder bonding is used to bond the electrode terminal to the conductive pattern, then large area bonding is achieved, but the solder remelts due to overheating during bonding, resulting in nonuniform bonding and reduced reliability
Solution Approach 1:
The patent replaces the thermal bonding process (solder bonding) with a mechanical bonding process (ultrasonic bonding). The ultrasonic bonding device uses mechanical vibration and pressure to bond the electrode terminal to the conductive pattern, eliminating the need for heating that causes solder remelting. This substitution of bonding mechanism resolves the contradiction by achieving both large area bonding and high reliability without thermal damage.
2Reliability
If ultrasonic bonding is used to bond the electrode terminal, then heating is avoided and solder remelting is prevented, but oxide films remain on the bonding surface, creating unbonded areas and reducing bonding strength
Solution Approach 1:
The patent utilizes mechanical vibration (ultrasonic vibration) not only for bonding but also for removing oxide films from the bonding surface. The high-frequency vibration mechanically disrupts and removes the oxide layer, exposing clean metal surfaces that can form strong bonds. This application of mechanical vibration resolves the contradiction by simultaneously preventing thermal damage and eliminating oxide films that would otherwise weaken the bond.
3Area of stationary object
If the bonding area is increased to accommodate large current, then current carrying capacity is improved, but oxide films in the center of the bonding surface cannot be pushed aside, leaving unbonded portions
Solution Approach 1:
The ultrasonic vibration applied during bonding creates mechanical energy that propagates through the bonding interface, effectively removing oxide films from the entire bonding surface including the center regions. This mechanical action ensures uniform bonding across the entire large bonding area, resolving the contradiction by maintaining bonding uniformity even as the bonding area increases to accommodate higher current requirements.
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
This approach enhances bonding strength and reliability by removing oxide films from the bonding surface, ensuring uniform bonding and allowing for post-bonding visual verification of the bonded area, thus addressing the limitations of conventional solder bonding and ultrasonic bonding techniques.
Implementation Method 1
a material to be bonded is bonded by being caused to vibrate ultrasonically while being pressurized through an ultrasonic horn
Implementation Method 2
the ultrasonic bonding breaks an oxide film on a surface to be bonded to push the oxide film aside to the outside of a bonded part
Data Source
AI summary
A semiconductor device of the present invention includes a bonding target and an electrode terminal bonded to the bonding target. The electrode terminal and the bonding target are bonded by ultrasonic bonding at a bonding surface to be subjected to bonding. The electrode terminal includes a penetrating hollow part surrounded on at least two sides by the bonding surface.