Liquid Ejection Head Wiring Layout to Prevent Bend-Induced Breakage
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Solution Overview
Problem
Existing liquid ejection head manufacturing methods risk breaking the flexible wiring substrate due to excessive stress when bending it on adhesive agent protrusions, leading to potential electrical failures.
Innovation Solution
The flexible wiring substrate is bent from a non-fixed portion as a starting point, with a groove or space formed to accommodate excess adhesive agent, preventing it from protruding and causing stress, and using a high-hardness adhesive agent to secure bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the flexible wiring substrate is bent on the protruding portion of the applied adhesive agent as a starting point, then the adhesive agent can be applied without requiring a groove or space, but the flexible wiring substrate will be subjected to excessive stress leading to breakage
Solution Approach 1:
The patent segments the flexible wiring substrate into a fixed portion (bonded to the support member) and a non-fixed portion (free to bend). The bending starting point is positioned in the non-fixed portion, separating the bending action from the bonded area. This segmentation allows the substrate to bend without transmitting excessive stress to the adhesive bond, preventing breakage while maintaining manufacturing simplicity.
Solution Approach 2:
The patent applies preliminary action by pre-defining the bending starting point in the non-fixed portion before the bending process. The flexible wiring substrate is configured in advance with a fixed portion and a non-fixed portion, so that when bending occurs, it starts from the predetermined location in the non-fixed portion. This preliminary configuration prevents the bending stress from concentrating at the adhesive interface, thereby avoiding substrate breakage.
2Reliability
If a groove or space is formed to accommodate excess adhesive agent, then the flexible wiring substrate is protected from breakage, but the device structure becomes more complex
Solution Approach 1:
The patent applies local quality by creating a groove or space only in the specific region where adhesive agent accumulation occurs, rather than modifying the entire support member structure. This localized feature accommodates excess adhesive agent without requiring complex overall structural changes, thus protecting the flexible wiring substrate from breakage while minimizing increases in device complexity.
3Strength
If the flexible wiring substrate is fully fixed to the support member, then bonding strength is maximized, but the substrate cannot be bent without causing floating or breakage
Solution Approach 1:
The patent segments the flexible wiring substrate into a fixed portion that is bonded to the support member and a non-fixed portion that remains free. This segmentation allows the fixed portion to provide strong adhesive bonding while the non-fixed portion maintains bending capability. The substrate can be bent from the non-fixed portion without compromising the bond strength of the fixed portion, thus resolving the contradiction between bonding strength and bending adaptability.
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 enhances the reliability of the flexible wiring substrate by preventing breakage and ensuring stable electrical connections.
Implementation Method 1
the flexible wiring substrate includes a fixed portion fixed to the support member by an adhesive agent
Data Source
AI summary
A liquid ejection head with improved reliability has an element substrate configured to eject a liquid according to an electric signal; a support member supporting the element substrate; and a flexible wiring substrate fixed to the support member and configured to supply the electric signal to the element substrate. On a surface of the support member supporting the element substrate, the flexible wiring substrate includes a fixed portion fixed to the support member by an adhesive agent and a non-fixed portion not fixed to the support member. The flexible wiring substrate is bent from a position included in the non-fixed portion as a starting point.