Thermal Printhead Protrusion Uniformity via Anisotropic Etching
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Solution Overview
Problem
Conventional thermal printheads face challenges in achieving uniform heat storage characteristics and printing quality due to variations in film thickness and material thermal conductivity, particularly with convex glaze layers formed by screen printing and single-crystal semiconductor protrusions.
Innovation Solution
A thermal printhead with a protrusion formed on a single-crystal semiconductor substrate, featuring a heat storage layer on top of the protrusion, where the substrate and protrusion are integrally formed, and the protrusion is created through anisotropic etching with a glaze layer of predetermined thickness, ensuring uniform heat storage and high thermal conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a convex glaze layer is formed by screen printing, then heat storage characteristics are improved, but film thickness varies causing non-uniform printing quality
Solution Approach 1:
The patent replaces the mechanical screen printing process with a chemical wet-etching process to form the convex glaze layer. This substitution eliminates the film thickness variation inherent in screen printing while maintaining the heat storage functionality of the convex structure.
Solution Approach 2:
The patent changes the formation method parameter from mechanical deposition (screen printing) to chemical etching (wet-etching). This parameter change enables precise control of the convex glaze layer thickness and shape, achieving uniform film thickness across the entire surface.
2Manufacturing precision
If a protrusion is formed by anisotropic etching of single-crystal semiconductor, then uniform shape is achieved, but high thermal conductivity reduces heat storage characteristics
Solution Approach 1:
The patent creates a composite structure where a glass glaze layer is formed on top of the single-crystal semiconductor protrusion. The glass material provides low thermal conductivity for heat storage, while the semiconductor substrate provides the uniform protrusion shape through anisotropic etching. This composite structure combines the advantages of both materials.
Solution Approach 2:
The patent applies different materials to different regions: the single-crystal semiconductor forms the uniform protrusion shape, while the glass glaze layer is applied specifically to the top surface where heat storage is needed. This local differentiation allows each material to perform its optimal function.
3Ease of manufacture
If screen printing is used to form glaze layer, then manufacturing is simplified, but product-to-product and location-to-location variation occurs
Solution Approach 1:
The patent replaces screen printing with wet-etching, substituting a mechanical deposition process with a chemical etching process. This substitution maintains ease of manufacture while achieving superior film thickness consistency, as wet-etching naturally produces uniform thickness across the substrate.
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 configuration ensures uniform pressure and heat distribution for improved printing quality and high-speed printing, while maintaining the advantages of single-crystal semiconductor thermal conductivity and reducing manufacturing complexity and costs.
Implementation Method 1
the substrate and the protrusion are integrally formed from a single-crystal semiconductor
Implementation Method 2
By passing an electric current between the upstream electrode layer and the downstream electrode layer, the exposed parts of the resistor layer (i.e., heat-generating parts) generates heat by Joule effect
Implementation Method 3
forming an intermediate glaze by subjecting the glaze layer to wet-etching
Implementation Method 4
forming the protrusion by anisotropic etching of the material substrate
Data Source
AI summary
A thermal printhead includes a substrate, a protrusion formed on an obverse surface of the substrate and extending in a main scanning direction, a heat storage layer formed on a top surface of the protrusion, and a plurality of heat-generating parts arranged along the main scanning direction on the heat storage layer. The substrate and the protrusion are integrally formed from a single-crystal semiconductor.