Wiring Board Alignment Marks for Thermal Expansion Compensation
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Solution Overview
Problem
The existing mount structures for wiring boards on electrooptic panels face challenges due to significant expansion and contraction of polyimide resin-based wiring boards, leading to pitch gaps and alignment issues, which complicate the alignment process and increase manufacturing costs.
Innovation Solution
A wiring board with a terminal group and alignment marks extending to a common phantom center point, allowing for easy alignment by maintaining similar triangle shapes before and after expansion or contraction, eliminating the need for operators to determine expansion or contraction amounts and simplifying the alignment process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the wiring board is made of polyimide resin to achieve flexibility and electrical insulation, then electrical insulation performance is improved, but the wiring board expands or contracts significantly with temperature and humidity changes, causing pitch gaps and alignment failure
Solution Approach 1:
The patent changes the material parameter from polyimide resin to glass fiber reinforced epoxy resin, which has significantly lower thermal expansion and moisture absorption coefficients. This material substitution maintains electrical insulation while eliminating the expansion/contraction that causes pitch gaps, thereby resolving the contradiction between reliability and manufacturing precision
Solution Approach 2:
The patent employs glass fiber reinforced epoxy resin, a composite material combining glass fibers with epoxy resin matrix. This composite structure provides both the electrical insulation required for wiring boards and the dimensional stability needed to prevent pitch gaps during assembly, simultaneously achieving reliability and manufacturing precision
2Adaptability or versatility
If the input terminals and connecting terminals are arranged in belt shape along multiple lines passing through a common point to accommodate expansion, then adaptability to thermal expansion is improved, but the alignment process becomes more complex requiring reference marks and scales
Solution Approach 1:
The patent extracts and eliminates the need for complex alignment reference marks and scales by preventing expansion-induced misalignment in the first place. By using dimensionally stable glass fiber reinforced epoxy resin, the terminals maintain their designed positions, making additional alignment features unnecessary and simplifying the overall device structure
Solution Approach 2:
Instead of designing the terminal arrangement to accommodate expansion (belt shape along multiple lines), the patent inverts the approach by selecting a material that does not expand significantly. This eliminates the need for complex geometric arrangements and reference marks, reducing alignment process complexity while maintaining adaptability
3Measurement precision
If thin linear patterns are used for the scale to achieve higher alignment accuracy, then alignment precision is improved, but the manufacturing yield decreases and cost increases due to difficulty in pattern formation
Solution Approach 1:
The patent removes the entire alignment reference mark and scale system from the design by preventing misalignment through material selection. This eliminates the need for thin linear patterns that are difficult to manufacture, thereby improving manufacturing yield and reducing costs while maintaining alignment accuracy through material dimensional stability
Solution Approach 2:
The patent replaces the expensive and low-yield thin linear pattern scale with a simpler, more manufacturable solution based on dimensionally stable material properties. The alignment accuracy is achieved through the inherent stability of the glass fiber reinforced epoxy resin rather than through fragile thin patterns, improving productivity and reducing manufacturing costs
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 solution ensures high alignment accuracy and simplifies the alignment process, reducing manufacturing costs and improving yield by maintaining proper terminal alignment despite thermal and moisture-induced changes.
Implementation Method 1
the glass fiber reinforced epoxy resin substrate which has a small coefficient of thermal expansion and a small coefficient of change in moisture absorption
Implementation Method 2
the glass fiber reinforced epoxy resin substrate which has a small coefficient of thermal expansion and a small coefficient of change in moisture absorption
Data Source
AI summary
There is provided a wiring board including: a terminal group including a plurality of terminals arrayed along a specified array axis; and a pair of alignment marks disposed on opposite sides of the terminal group in the direction of the array axis. The alignment marks each have a first portion extending so as to intersect at an angle to the array axis. The first portions of the alignment marks and the plurality of terminals extend from the terminal group to a common phantom center point that is apart from the terminal group in the direction intersecting the array axis.