Thermal Print Head Wiring Layout for Narrow Width and Low Voltage Drop
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing thermal print heads face challenges in efficiently arranging pads for wire bonding, leading to increased width and susceptibility to defects, as well as voltage drops due to restricted pad arrangements.
Innovation Solution
The thermal print head design includes a substrate with a bump and wiring layers arranged in specific directions, allowing for pads to be aligned in a line, reducing width and minimizing voltage drops through a thicker wiring layer and electrical connections that expose a heat-generating body film for efficient heat generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If pads are arranged in multiple rows along the first direction for wire bonding, then the thermal print head can accommodate more wire bonding connections, but the width of the thermal print head increases
Solution Approach 1:
The patent transitions from a conventional multi-row pad arrangement (occupying lateral width) to a linear single-row pad arrangement along the longitudinal direction. By repositioning pads in a line along the first direction and extending the substrate lengthwise, the design accommodates multiple wire bonding connections without increasing width, effectively moving the solution from two-dimensional lateral distribution to one-dimensional longitudinal distribution.
2Adaptability or versatility
If pads are arranged in multiple rows, then wire bonding connections are accommodated, but the thermal print head becomes more susceptible to defects
Solution Approach 1:
By reconfiguring the pad arrangement from multiple rows (increasing lateral complexity) to a single line along the longitudinal direction, the patent reduces the number of pad-row interfaces and alignment points, thereby reducing potential defect locations. The linear arrangement simplifies the wire bonding process and reduces susceptibility to manufacturing defects.
3Adaptability or versatility
If pads are arranged in multiple rows, then wire bonding is enabled, but voltage drops increase due to restricted pad arrangements
Solution Approach 1:
The linear arrangement of pads along the longitudinal direction allows for optimized wiring paths that reduce current travel distance and resistance. By eliminating the need for lateral wire routing across multiple rows, the design reduces voltage drops associated with longer and more complex electrical pathways.
Solution Approach 2:
The patent merges multiple pad rows into a single linear pad arrangement, consolidating the electrical connection points along one direction. This merging simplifies the electrical architecture and reduces the total length of wiring required, thereby minimizing voltage drops and energy loss.
4Ease of manufacture
If a conventional pad arrangement is used, then wire bonding is achieved, but the thermal print head width increases
Solution Approach 1:
The patent maintains ease of wire bonding implementation by providing adequate pad spacing and access, but achieves this along the longitudinal direction rather than laterally. The linear pad arrangement allows wire bonding operations to proceed efficiently while constraining the width of the device.
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 design enhances manufacturing yield, reduces defects, and minimizes voltage drops, enabling more efficient and compact thermal print head production.
Implementation Method 1
The wiring layer is arranged on the main surface with the resistor layer interposed therebetween. The wiring layer includes a common electrode and a plurality of individual electrodes... Each of the individual electrodes includes a second base and a second extension. The second extension extends from the second base along the second direction. A tip of the second extension overlaps with the protrusion in a plan view, and faces the tips of the first extensions with a gap left therebetween. That is, the resistor layer under the wiring layer is exposed from between the tips of the first extensions and the tip of the second extension.
Data Source
AI summary
A thermal print head includes: a substrate including a main surface; an insulating film arranged on the main surface; a first wiring layer arranged on the insulating film; a first interlayer insulating film arranged on the first wiring layer; a heat-generating body film; and a second wiring layer arranged on the first interlayer insulating film with the heat-generating body film interposed therebetween, wherein a bump is formed on the main surface, wherein the bump extends along a first direction in a plan view, wherein the second wiring layer extends along a second direction orthogonal to the first direction to intersect the bump in a plan view, and includes first, second, third, and fourth wirings arranged along the first direction, wherein the second wiring is located between the first wiring and the third wiring, and wherein the third wiring is located between the second wiring and the fourth wiring.