Ink Jet Head Electrode Protection Member Design
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Solution Overview
Problem
The existing ink jet head structures face challenges in protecting the electrode portion of the wiring board, which is prone to peeling off or breaking due to stress, and assembling difficulties arise from the small gap between the electrode and adjacent members, making it hard to apply protective coatings without pinholes.
Innovation Solution
An ink jet head design featuring a holding member that covers the electrode portion and an electrode protection member with weak adhesion, made of polytetrafluoroethylene or polyolefin, bonded between the holding member and the electrode portion using an epoxy-type adhesive, to absorb stress and prevent disconnection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the electrode portion is formed on the wiring board made of ceramic by aluminum evaporation, then the manufacturing process is simplified and cost is reduced, but the bonding strength between the electrode portion and the wiring board body becomes weak making it prone to peeling off
Solution Approach 1:
An adhesive layer is introduced as an intermediary between the electrode portion and the wiring board body. This adhesive layer serves as a mediator that provides stronger bonding than the direct aluminum evaporation bonding, preventing the electrode portion from peeling off while maintaining the simplicity of the manufacturing process.
Solution Approach 2:
The structure transitions from a single-material bonding (aluminum evaporation on ceramic) to a composite material structure involving the adhesive layer. This composite approach combines the advantages of both the electrode material and the adhesive material to achieve both ease of manufacture and strong bonding.
2Reliability
If the gap between the electrode portion and other adjacent members is increased to prevent stress application, then the electrode portion is protected from peeling off, but the assembling work becomes very difficult
Solution Approach 1:
The adhesive layer acts as a stress-absorbing intermediary between the electrode portion and surrounding components. It allows the electrode portion to remain in close proximity to adjacent members for easy assembly while the adhesive absorbs and distributes stress, preventing peeling.
Solution Approach 2:
The adhesive layer changes the mechanical parameters of the bonding interface by providing different elasticity and adhesion properties. This allows the structure to maintain small gaps for easy assembly while the adhesive's material properties prevent stress-induced peeling.
3Reliability
If a filling material is coated to protect the electrode portion, then the electrode portion is protected from stress, but it becomes very difficult to coat the filling material thinly and without generating pinholes in the small gap between the electrode portion and other members
Solution Approach 1:
The adhesive layer serves as a thin, disposable protective element that can be applied uniformly without the complexity of coating filling materials. It provides sufficient protection against stress while being easy to apply thinly and uniformly in the small gap, avoiding pinhole formation issues.
Solution Approach 2:
The adhesive layer's material parameters (viscosity, adhesion, thickness) are optimized to allow thin, uniform coating in small gaps. This enables effective protection of the electrode portion while maintaining coating uniformity and avoiding pinholes that would occur with filling materials.
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
The electrode protection member effectively absorbs stress instead of the electrode portion, preventing peeling and disconnection, and allows for easier coating and assembly by ensuring the electrode portion remains intact, enhancing the reliability and efficiency of the ink jet head.
Implementation Method 1
a piezoelectric element is provided to each nozzle for ejecting ink, and by making shear deformation of this piezoelectric element an ink is ejected from the each nozzle
Implementation Method 2
an electrode portion protection member bonded between the holding member and the electrode portion by using adhesive
Data Source
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AI summary
Disclosed is an ink jet head exhibiting good assemblability while protecting an electrode portion. An ink jet head (10) comprising a head chip (2) including drive walls (22) and channels (23) juxtaposed alternately with a drive electrode (25) being formed on the drive wall (22), and a nozzle plate (24) wherein a connection electrode is formed on the rear surface of the head chip (2), a wiring board (3) on which an electrode portion (32) is formed is bonded to project from the head chip (2), and ink in the channel (23) is ejected by causing shear deformation of the drive wall (22) is further provided with a holding member (5) disposed at a position covering the electrode portion (32) and holding a portion (31) of the wiring board (3) projecting from the head chip (2), and an electrode portion protection member (4) bonded between the holding member (5) and the electrode portion (32) using adhesive and having a thickness in the range of 0.01-0.5 mm at a part covering the electrode portion (32).