Touch Panel Border Alignment via Inverted Fabrication Sequence
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Solution Overview
Problem
The existing fabrication processes for capacitive touch panels face challenges in achieving the required precision and production capacity due to the need for narrow borders and precise alignment between the patterned transparent conductive layer and the metal trace, leading to difficulties in meeting the specifications of overlapping width and pitch.
Innovation Solution
The method involves forming a patterned metal layer on the border region before forming the patterned transparent conductive layer, which reduces the shift range between the contact regions to less than 150 μm, and baking the transparent conductive layer before patterning to prevent undesirable phenomena like warpage and bluing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the patterned transparent conductive layer and metal trace are formed using conventional photolithography and silver screen printing processes, then the touch panel can be manufactured, but the precision and production capacity are insufficient to meet the narrow border requirements (overlapping width d1 < 0.3 mm and pitch d2 < 0.5 mm)
Solution Approach 1:
The metal trace layer is formed on the substrate before the transparent conductive layer is patterned. This preliminary formation of the metal trace establishes a stable reference structure that subsequent processing steps can align to, thereby improving overall alignment precision while maintaining production efficiency
Solution Approach 2:
The conventional fabrication sequence is inverted: instead of first forming the transparent conductive layer pattern and then adding the metal trace, the metal trace is formed first on the substrate, followed by forming and patterning the transparent conductive layer. This inversion allows the metal trace to serve as the primary alignment reference, improving precision without sacrificing productivity
2Ease of manufacture
If the transparent conductive layer is patterned before baking, then the fabrication process can proceed, but warpage and bluing phenomena occur
Solution Approach 1:
The transparent conductive layer is baked to remove organic residues and stabilize its structure before the photolithography patterning process. This preliminary thermal treatment prevents warpage and bluing during subsequent processing by eliminating volatile components that would otherwise cause structural instability
Solution Approach 2:
Baking the transparent conductive layer before patterning acts as a preventive measure that removes potential sources of structural instability (organic residues and moisture). This beforehand treatment cushions against the development of warpage and bluing phenomena during the patterning and assembly processes
Data Source
AI summary
A touch panel is provided. The touch panel includes: a substrate, wherein the substrate includes a viewing region and a border region at an edge of the viewing region; a patterned transparent conductive layer formed on the substrate, wherein the patterned transparent conductive layer is formed on the viewing region and the border region, and the patterned transparent conductive layer has a touch sensitive function; and a patterned metal layer formed on the border region, wherein the patterned metal layer includes a contact region and a trace region connecting to the contact region, and at least a portion of the contact region overlaps with the patterned transparent conductive layer, wherein a shift range between the contact region and the patterned transparent conductive layer disposed on the border region adjacent to the contact region is smaller than about 150 μm.