Gold Wiring Adhesion via Base Layer Exposure in Electronic Devices
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Solution Overview
Problem
The existing bonding techniques using gold (Au) wiring in electronic devices suffer from weak adhesive strength, particularly in configurations with high-density wiring, leading to insufficient bonding reliability.
Innovation Solution
The solution involves forming a base layer on the drive substrate with gold wiring, exposing a portion of it, and applying a bonding resin to the exposed base layer, which increases the bonding strength between the drive substrate and the stacked body. This configuration includes a wiring metal removal region that is surrounded by gold wiring, with a surface treatment using an organic molecule with functional groups, enhancing adhesion. Additionally, using a base layer made of a different metal can secure conductivity and reduce electrical resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gold (Au) wiring is used for driving the drive element, then electrical resistance is reduced and conductivity is improved, but adhesive strength with bonding resin becomes weak and bonding reliability deteriorates
Solution Approach 1:
The patent applies local quality by creating a wiring metal removal region where gold wiring is selectively removed to expose the base layer. This local modification allows the bonding resin to directly contact the base layer in specific areas, improving adhesive strength at the bonding interface while maintaining gold wiring in other areas for optimal conductivity. The selective removal creates different local properties: high conductivity where gold is present and high adhesion where the base layer is exposed.
Solution Approach 2:
The base layer serves as an intermediary between the gold wiring and the bonding resin. By removing portions of the gold wiring, the base layer is exposed to directly bond with the bonding resin, acting as a mediating layer that provides both electrical connection (through the underlying structure) and improved adhesive properties. This intermediary approach resolves the conflict between gold's excellent conductivity and poor adhesion to bonding resin.
2Productivity
If high-density wiring is implemented on the substrate, then miniaturization and integration are achieved, but the bonding strength in wiring portions becomes insufficient and adhesive peeling occurs
Solution Approach 1:
The patent applies local quality by creating specific wiring metal removal regions where gold wiring is selectively removed to expose the base layer. This local modification allows the bonding resin to directly contact the base layer in specific areas, improving adhesive strength at the bonding interface while maintaining gold wiring in other areas for optimal conductivity. The selective removal creates different local properties: high conductivity where gold is present and high adhesion where the base layer is exposed.
Solution Approach 2:
The patent applies preliminary action by pre-creating the wiring metal removal region before final bonding. The base layer is exposed in advance in strategic locations, allowing the bonding resin to form strong bonds with the base layer during the bonding process. This preliminary preparation ensures that when high-density wiring is implemented, the bonding interfaces are already optimized for strong adhesion, preventing adhesive peeling even in highly integrated configurations.
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 significantly improves the adhesion reliability and bonding strength, especially in high-density Au wiring configurations, while maintaining conductivity and minimizing electrical resistance.
Implementation Method 1
a surface treatment using an organic molecule with functional groups, enhancing adhesion
Data Source
AI summary
An electronic device includes a drive substrate (a pressure chamber substrate and a vibration plate) including a piezoelectric element and electrode wirings related to driving of the piezoelectric element formed thereon, and a sealing plate bonded thereto, the electrode wirings are made of wiring metal containing gold (Au) on the drive substrate through an adhesion layer which is a base layer, and has a removed portion in which a portion of the wiring metal in a region containing a part bonded to a bonding resin is removed and the adhesion layer is exposed.