Display Substrate Contact Pads for Heat-Humidity Chip Bonding
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Solution Overview
Problem
The issue of driver chip detachment during reliability tests under high temperature and high humidity conditions due to the multi-layer pin structure in traditional display substrates, where the organic layer covering the pin is removed, leading to poor bonding with the driver chip.
Innovation Solution
A display substrate design with a contact pad insulating layer having varying thicknesses, exposing the contact pad surfaces and edges, and incorporating dummy and array test contact pads to enhance bonding reliability, along with a specific arrangement of contact pads and conductor portions to improve connectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the organic layer covering the pin is removed to expose the pin surface, then the pin becomes accessible for bonding, but the bonding reliability deteriorates under high temperature and high humidity conditions
Solution Approach 1:
The contact pad insulating layer is designed with non-uniform thickness: a first thickness in gaps between adjacent contact pads to provide insulation and protection, and a second thickness (smaller than the first) in the region between input and output contact pads to expose surfaces for bonding. This local differentiation allows simultaneous achievement of pin accessibility and bonding reliability under harsh conditions.
2Strength
If a multi-layer pin structure is used to increase pin height for enhanced bonding, then bonding capability is improved, but the driver chip becomes prone to detachment under reliability test conditions
Solution Approach 1:
The invention changes the thickness parameter of the contact pad insulating layer in different regions. By setting the thickness to a first value in gaps between contact pads and a second value (smaller than the first) in the bonding region, the structure achieves both adequate insulation strength and proper bonding surface exposure, eliminating the need for multi-layer pin structures while maintaining driver chip attachment reliability.
Data Source
AI summary
A display substrate, a method of manufacturing the display substrate, and a display device are provided. The display substrate includes: a base substrate, a plurality of sub-pixels, a gate driving circuit, a plurality of input contact pads, a plurality of output contact pads and a contact pad insulating layer. Surfaces of the input contact pads away from the base substrate and surfaces of the output contact pads away from the base substrate are exposed from the contact pad insulating layer. The contact pad insulating layer includes a first portion having a first thickness and a second portion having a second thickness smaller than the first thickness. Edges of the input contact pads and edges of the output contact pads are covered by the first portion. The second portion is located in the region between the input contact pads and the output contact pads.