Liquid Ejection Unit Wire Bonding to Prevent Board Gaps
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Solution Overview
Problem
Existing liquid ejection units face issues with wire bonding where the wire's elastic deformation creates a gap between the print element board and the electric wiring board, leading to instability in the electric connection and potential leakage of sealing agent, which compromises the reliability of the connection.
Innovation Solution
The solution involves using a specific shape for the electric connection members with first and second bending portions and a horizontal section to reduce elastic deformation, combined with a sealing agent that fixes and protects the connection, thereby minimizing gaps and ensuring reliable electrical contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a normal loop shape wire is used for electric connection, then the wire bonding process is simple, but the wire's elastic deformation creates a gap between the print element board and the electric wiring board, causing sealing agent leakage and reducing connection reliability
Solution Approach 1:
The wire is designed with a specific bent shape including a first bending portion, horizontal section, and second bending portion, rather than a simple continuous loop. This curvature configuration reduces elastic deformation and prevents gap formation between boards while maintaining manufacturing feasibility
Solution Approach 2:
The wire shape parameters are specifically controlled with the horizontal section having a length of 0.01 to 0.5 times the wire length, and bending portions with specific curvature radii. These parameter changes optimize the wire's mechanical properties to minimize elastic deformation and prevent sealing agent leakage
2Reliability
If the wire is made more rigid to reduce elastic deformation, then the gap formation is reduced, but the wire bonding process becomes more difficult and may damage the electrode pads
Solution Approach 1:
Instead of changing wire material rigidity, the patent changes the wire's geometric parameters - specifically the bent shape with controlled curvature radii and horizontal section length. This achieves reduced elastic deformation without increasing manufacturing difficulty or risking electrode pad damage
Solution Approach 2:
The bent wire shape with specific curvature in the first and second bending portions distributes stress more effectively, reducing the reaction force that causes gap formation while maintaining wire flexibility for easy bonding and electrode pad safety
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 stabilizes the electric connection by reducing the reaction force on the wiring board, preventing sealing agent leakage, and maintaining high reliability even with increased electrode pads and wires, thus enhancing the overall performance of the liquid ejection unit.
Implementation Method 1
a sealing agent is supplied to fill the gap
Implementation Method 2
electric connection members 106...connecting the electrode pads 107 and the terminals 110 to one another by wire bonding
Data Source
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AI summary
A manufacturing method of a liquid ejection unit (101) includes: arranging (S1201, S1202) an electric wiring board (103) on a print element board (102) such that the electric wiring board (103) abuts the print element board (102), the print element board (102) including an ejection port (109) configured to eject liquid, an energy generating element (108) configured to generate energy for ejecting the liquid from the ejection port (109), and an electrode pad (107) electrically connected to the energy generating element (108), the electric wiring board (103) including a terminal (110) for electrical connection to the electrode pad (107); connecting (S1203) the electrode pad (107) and the terminal (110) to each other by using an electric connection member (106); and covering (S1204, S1205) an electric connection portion with a sealing agent (104), the electric connection portion including at least the electric connection member (106), the electrode pad, and the terminal (110), in which in the connecting, the electric connection member (106) is shaped to include at least one bending point (106g).