Transparent Electrode Interconnection via Adhesional Wetting
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Solution Overview
Problem
Circuit board interconnections using anisotropic conductive films (ACFs) with solder particles result in increased electrical resistance and unreliable connections, especially when soldering to thin ITO electrodes, as the soldering process can corrode the ITO electrodes, leading to poor electrical continuity.
Innovation Solution
A circuit board interconnection structure and method utilizing metal-containing conductive particles and a thermoset resin, where the conductive particles adhesinally wet the transparent metal oxide electrodes, forming a reinforcing resin portion to create a reliable connection without alloy formation, using thermocompression bonding to enhance the joining process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solder particles are used as conductive particles to enable soldering between electrodes, then electrical connection reliability is improved, but the thin ITO electrodes may corrode due to alloying with solder material, causing poor electrical continuity
Solution Approach 1:
The patent introduces a barrier layer between the ITO electrode and the solder particles to prevent direct contact and alloying. This intermediary layer acts as a protective mediator that allows electrical connection while preventing corrosion of the thin ITO electrode by the solder material.
Solution Approach 2:
The patent uses a composite conductive material consisting of solder particles combined with other materials that provide both electrical conductivity and protective functions. This composite structure enables reliable electrical connection while preventing harmful alloying effects on the ITO electrode.
2Ease of operation
If anisotropic conductive film (ACF) is used to join electrodes, then ease of interconnection is improved, but electrical resistance increases and connection reliability decreases
Solution Approach 1:
The patent changes the key parameter of the conductive material from mere particle contact (in ACF) to actual soldering with metal-containing particles. This parameter change transforms the connection mechanism to achieve both ease of interconnection and low electrical resistance with high reliability.
3Reliability
If soldering is performed on thin metal oxide films, then electrical continuity is improved, but the thin films are easily corroded, impairing conductivity
Solution Approach 1:
The barrier layer serves as an intermediary between the solder and the thin metal oxide film, enabling electrical continuity through the soldering process while preventing corrosion that would compromise the film's integrity and conductivity.
Solution Approach 2:
The barrier layer is formed on the ITO electrode surface before the soldering process. This preliminary protective action prevents the subsequent soldering from corroding the thin metal oxide film, preserving both electrical continuity and film integrity.
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 prevents corrosion of the thin metal oxide films, reduces electrical resistance, and ensures a reliable and stable connection between circuit boards with transparent electrodes, improving the reliability and durability of the interconnection.
Implementation Method 1
heating the interconnecting material mixture to a predetermined temperature Ta at which the thermoset resin thermally cures
Implementation Method 2
a first abutting portion of the one or more joining portions abutting the first electrode, being formed by adhesional wetting of the first electrode with the conductive material
Implementation Method 3
one or more joining portions formed of a metal-containing conductive material for joining the first and second electrodes
Data Source
AI summary
Provided is a circuit board interconnection structure including: a first circuit board including a first substrate and a first electrode formed on a surface of the first substrate; a second circuit board including a second substrate and a second electrode formed on a surface of the second substrate; one or more joining portions formed of a metal-containing conductive material for joining the first and second electrodes, interposed between the first and second electrodes; and a reinforcing resin portion for reinforcing the one or more joining portions. The first electrode is a transparent electrode including a metal oxide film. A first abutting portion of the joining portion abutting the first electrode, is formed by adhesional wetting of the first electrode with the conductive material.