Conductive Paste Contact for Light Emitting Device
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Solution Overview
Problem
Existing light emitting devices face issues with loose connections due to size differences in connection electrodes caused by process errors, leading to deformation and poor contact, resulting in dead pixels, reduced brightness, and decreased product reliability and throughput.
Innovation Solution
A light emitting device with a paste-type electrical contact portion having conductivity, viscosity, and thermal resistance, typically made of Ag, Cu, or Au, is used to improve the electrical connection between the connection electrode and the drain electrode, addressing height differences and stress-induced deformations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a spacer structure is used to form connection electrodes, then the connection electrode can be formed with a defined height, but process errors cause size differences between connection electrodes leading to loose connections
Solution Approach 1:
The patent introduces an electrical contact portion made of conductive paste as an intermediary element between the connection electrode and the drain electrode. This paste layer compensates for height differences and dimensional variations in the spacer structure, ensuring reliable electrical contact even when connection electrode heights vary due to process errors.
Solution Approach 2:
The patent changes the physical state and properties of the electrical contact by using conductive paste with specific viscosity and thermal resistance parameters. These parameter changes allow the contact portion to adapt to dimensional variations and maintain reliable electrical connection despite manufacturing tolerances.
2Ease of manufacture
If substrates are attached with concentrated stress on a part, then attachment is facilitated, but the spacer deforms and floats up causing loose contact
Solution Approach 1:
The electrical contact portion acts as a mediator that absorbs the stress and deformation effects. Even when the spacer deforms due to concentrated attachment stress, the conductive paste maintains electrical contact by compensating for the dimensional changes and floating of the spacer structure.
Solution Approach 2:
The conductive paste provides beforehand cushioning against the deformation and floating of the spacer during substrate attachment. The paste's viscosity and compliance allow it to absorb dimensional changes and maintain stable electrical contact despite stress-induced deformations.
3Illumination intensity
If the device operates at high temperature, then light emission performance is improved, but heat causes spacer deformation leading to loose contact
Solution Approach 1:
The patent utilizes the thermal properties of the conductive paste, specifically its thermal resistance parameter, to manage heat effects. The paste maintains its electrical conductivity and physical integrity at operating temperatures, compensating for thermal expansion and deformation of the spacer structure while allowing the device to operate at high temperatures for improved light emission.
Solution Approach 2:
The electrical contact portion serves as a thermal intermediary that buffers the thermal effects between the light emitting portion and the connection structure. It maintains electrical contact stability despite heat-induced deformations of the spacer.
4Strength
If a rigid connection structure is used, then structural stability is improved, but process errors cause loose connections due to size variations
Solution Approach 1:
The patent changes the mechanical parameters of the electrical contact from rigid to compliant by using conductive paste with appropriate viscosity. This allows the contact portion to accommodate dimensional variations in the spacer structure while maintaining strong electrical connection, effectively decoupling structural strength from manufacturing precision 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
The solution enhances the electrical connection state, preventing loose contacts and improving the reliability and lifespan of the device by maintaining consistent contact despite process errors and heat-induced deformations.
Implementation Method 1
A light emitting device comprises a first pixel portion that includes a light emitting portion arranged between two electrodes on a first substrate. The light emitting device further comprises a transistor portion formed on a second substrate arranged to be opposed to the first substrate, a connection electrode extended from one of the two electrodes, and an electrical contact portion in surface contact with both the connection electrode and a drain of the transistor portion.
Data Source
AI summary
A light emitting device comprises a first pixel portion that includes a light emitting portion arranged between two electrodes on a first substrate, a transistor portion formed on a second substrate arranged to be opposed to the first substrate, a connection electrode extended from one of the two electrodes, and an electrical contact portion in surface contact with both the connection electrode and a drain of the transistor portion.