Circuit Board Wire Pattern Segmentation for Adhesive Bonding
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Solution Overview
Problem
The existing bonding methods for circuit boards in liquid ejection heads result in uneven adhesive spread due to the undulating wire patterns, leading to adhesive leakage and inappropriate bonding, which compromises the reliability of the connection.
Innovation Solution
The wire patterns are divided into portions with slits to maintain uniform widths, allowing the adhesive to spread evenly and preventing leakage and inappropriate bonding by controlling the flow resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wire patterns are used to connect terminals on a circuit board, then electrical connection is achieved, but the undulating shape of wire patterns causes uneven adhesive spread during bonding
Solution Approach 1:
The wire pattern is divided into multiple segments by introducing slits, transforming a single continuous conductive path into multiple separated sections. This segmentation allows the adhesive to flow uniformly across the bonding surface without being blocked by the undulating wire pattern, while the electrical connection function is maintained through the segmented conductive paths.
Solution Approach 2:
The slit is strategically positioned only in the wide portion of the wire pattern, not throughout its entire length. This local modification creates uniform width sections where adhesive can spread evenly, while preserving the necessary wire pattern structure in other areas for electrical connectivity and mechanical integrity.
2Reliability
If adhesive is applied to bond the circuit board to the support substrate, then bonding is achieved, but adhesive leakage occurs in areas where wire patterns are present
Solution Approach 1:
By segmenting the wire pattern with slits, the adhesive is prevented from being blocked and redirected by the undulating wire shape. The segmented structure creates a flat bonding surface that allows controlled adhesive application without leakage, while maintaining electrical connectivity through the segmented conductive paths.
3Adaptability or versatility
If wire patterns with varying widths are used for electrical connection, then design flexibility is improved, but adhesive flow resistance becomes uneven leading to inappropriate bonding
Solution Approach 1:
The slit is applied locally only to the wide portion of the wire pattern, creating a uniform width section specifically for adhesive bonding. This local modification ensures even adhesive flow and consistent bonding, while the rest of the wire pattern maintains its original design flexibility for electrical connection requirements.
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 ensures reliable bonding of the circuit board by evenly distributing the adhesive, preventing leakage and ensuring consistent contact between the circuit board and the support substrate.
Implementation Method 1
The circuit board is bonded, with an adhesive, to the support substrate via an insulation layer positioned on the wire pattern
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A wire pattern (23A) is divided into a plurality of portions (23A-1, 23A-2) in order to provide a circuit board for which very reliably bonding can be achieved and a liquid ejection head including the circuit board.