Ti Layer Thickness Variation for Au Bump Bonding
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Solution Overview
Problem
Existing electronic components with a thick Ti layer as the uppermost layer on the wiring electrode experience increased resistance and loss, while a thin Ti layer can reduce bonding strength between the Au layer and the Au bump.
Innovation Solution
The electronic component design includes a wiring electrode with a first Ti layer as the uppermost layer, where the thickness of the Ti layer is greater under the Au bump than in other areas, ensuring reduced loss and enhanced bonding strength by controlling Ti deposition on the Au layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the Ti layer as the uppermost layer of the wiring electrode is made thick, then the bonding strength between the Au layer and the Au bump is improved, but the resistance value of the wiring electrode increases and loss increases
Solution Approach 1:
The Ti layer is designed with non-uniform thickness: thicker in regions where Au bumps are bonded to provide sufficient bonding strength, and thinner in regions where Au bumps are not present to minimize electrical resistance and energy loss. This spatial variation in thickness allows simultaneous optimization of both bonding strength and electrical performance.
Solution Approach 2:
The wiring electrode structure is segmented into different regions with different Ti layer thicknesses based on functional requirements. The region under Au bumps has increased Ti thickness for bonding, while other regions maintain reduced Ti thickness for low resistance, effectively dividing the electrode into functionally optimized zones.
2Loss of energy
If the Ti layer as the uppermost layer of the wiring electrode is made thin, then the electrical resistance and loss are reduced, but the amount of Ti deposited on the Au layer increases which may reduce bonding strength
Solution Approach 1:
The Ti layer thickness is locally optimized: thin in regions without Au bumps to minimize resistance and loss, while thick in regions with Au bumps to prevent excessive Ti deposition on the Au layer and maintain bonding strength. This resolves the contradiction by making the Ti layer thickness location-dependent rather than uniform.
Solution Approach 2:
Instead of uniformly reducing Ti layer thickness across the entire wiring electrode, the invention applies partial thickness reduction only in regions where it is beneficial (areas without Au bumps), while maintaining adequate thickness in regions where bonding is required. This selective approach prevents the harmful effect of excessive Ti deposition on Au layers while still achieving loss reduction.
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 configuration effectively reduces electrical resistance and maintains high bonding strength between the Au layer and the Au bump, preventing bonding strength degradation.
Implementation Method 1
the uppermost layer of the wiring electrode is a first Ti layer
Data Source
AI summary
An electronic component including a pad electrode provided on a wiring electrode and a Au bump provided on the pad electrode, wherein the uppermost layer of the wiring electrode is a first Ti layer, the uppermost layer of the pad electrode is a Au layer, and the thickness of the first Ti layer in at least a portion on which the Au bump is superposed in plan view is greater than the thickness of at least a portion of the first Ti layer in a portion on which the Au bump is not superposed in plan view.