Wedge Tool Groove Geometry for Copper Wire Bonding Stability
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Solution Overview
Problem
In semiconductor devices, the use of copper wiring members reduces thermal fatigue, but the high rigidity of copper can cause the wedge tool to tilt during ultrasonic bonding, leading to uneven bonding and potential damage to the semiconductor element or circuit board.
Innovation Solution
A wedge tool with a groove in its end portion that is inclined along the longitudinal direction of the wiring member, allowing the heel side to be closer to the bonding surface than the toe side, which prevents the tool from tilting and ensures uniform bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copper is used as a bonding wire instead of aluminum, then thermal fatigue resistance is improved, but the wedge tool may tilt during bonding causing damage to the semiconductor element
Solution Approach 1:
The invention introduces a groove structure at the end portion of the wedge tool that creates localized geometric features. This groove has different depths at different locations (deeper at the heel side, shallower at the toe side), creating local quality variations that guide the copper wire into proper positioning and prevent tool tilting during bonding, thereby resolving the contradiction between using copper for thermal fatigue resistance and preventing damage to the semiconductor element.
2Strength
If a wedge tool presses a copper wire against a bonding surface, then bonding strength is improved, but the tool may have abnormal amplitude causing damage to the tool or wire
Solution Approach 1:
The invention modifies the geometric parameters of the wedge tool end portion by introducing a groove with specific depth variations. The groove depth changes from the heel side to the toe side, creating parameter changes in the tool's contact geometry with the copper wire. This geometric modification stabilizes the tool's vibration characteristics during ultrasonic bonding, preventing abnormal amplitude while maintaining strong bonding, thus resolving the contradiction between bonding strength and tool stability.
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 design stabilizes the bonding process, preventing damage to the semiconductor device and ensuring reliable wedge bonding by maintaining contact with the wiring member while suppressing abnormal amplitude and tool damage.
Implementation Method 1
a wedge tool that presses a wiring member against a bonding surface of a structure to which the wiring member is bonded by a wedge bonding method
Implementation Method 2
a groove that is provided in the end portion of the wedge tool body, that is configured to extend along a longitudinal direction of said wiring member, and that is inclined so that the groove on the heel side of the wedge tool body is closer to said bonding surface than the groove on the toe side of the wedge tool body
Data Source
AI summary
A bonding tool includes a wedge tool that presses a bonding wire against a principal plane of a structure such as an electrode to which the bonding wire is to be bonded. A groove formed in an end portion of a wedge tool body of the wedge tool is inclined along a longitudinal direction of the bonding wire so that a heel side of the groove is closer to the principal plane of the structure than a toe side of the groove. As a result, the wedge tool is inclined at a tilt angle and the bonding wire fits the groove in the end portion of the wedge tool body along the longitudinal direction of the bonding wire. Thus, a corner portion of the wedge tool does not contact the electrode.