Thermal Print Head Conduction Path via Substrate
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Solution Overview
Problem
Conventional thermal print heads face challenges in achieving fine printing due to the need for reduced pitch of heat generating portions, which requires a finer wiring layer pattern, but this is limited by the area available on the substrate surface.
Innovation Solution
The thermal print head incorporates a semiconductor substrate as part of the conduction path for energizing heat generating portions, allowing for a reduced wiring layer area on the surface, enabling more freedom in designing finer patterns and narrower pitches without compromising conduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the pitch of heat generating portions is reduced to achieve fine printing, then printing resolution is improved, but the wiring layer area becomes insufficient
Solution Approach 1:
The patent extends the conduction path from the wiring layer into the thickness direction of the substrate, utilizing the third dimension (depth) to provide additional conduction area. Through-holes penetrating the substrate allow conduction paths to extend below the wiring layer, effectively increasing the available conduction area without occupying more surface area, thus resolving the contradiction between reduced pitch and sufficient wiring area.
Solution Approach 2:
The patent embeds conduction paths within the substrate thickness, nesting the conduction function inside the substrate structure. The through-holes and internal conduction paths are nested within the substrate body, allowing the wiring layer to maintain its surface position while the conduction function is nested deeper in the substrate, effectively multiplying the conduction area without increasing surface footprint.
2Manufacturing precision
If the wiring layer is formed into a fine pattern to reduce pitch, then heat generating portion pitch is reduced, but wiring conduction reliability deteriorates
Solution Approach 1:
The patent compensates for the reduced surface area of fine-pitch wiring by extending conduction paths into the thickness direction through through-holes. This dimensional extension provides alternative conduction routes that maintain reliability even when surface wiring dimensions are reduced for fine pitch, effectively decoupling pitch reduction from reliability deterioration.
Solution Approach 2:
The substrate itself acts as an intermediary conduction medium, providing additional conduction paths through its thickness. The through-holes filled with conductive material serve as intermediary conduction channels between the wiring layer and the opposite substrate surface, enabling reliable conduction without relying solely on the fine-pitch surface wiring.
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 enables the downsizing and pitch-narrowing of heat generating portions, facilitating fine printing while ensuring proper conduction, and allowing for a larger area for the wiring layer on the substrate surface.
Implementation Method 1
a resistor layer formed on the semiconductor substrate and having a plurality of heat generating portions arranged in a main scanning direction
Data Source
AI summary
A thermal print head includes a semiconductor substrate, a resistor layer and a wiring layer. The resistor layer is formed on the semiconductor substrate and has a plurality of heat generating portions arranged in the main scanning direction. The wiring layer is formed on the semiconductor substrate to be included in a conduction path for energizing the plurality of heat generating portions. The conduction path includes a path or paths provided by the semiconductor substrate itself.