Liquid Discharge Head FPC Mounting Step Design
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Solution Overview
Problem
In liquid discharge devices like inkjet printers, the fine pitch wiring and thick plating can lead to warping and unintended connections between electrodes, and the thick insulating cover layer reduces mounting options, necessitating longer flexible printed circuits or fewer mounting portions.
Innovation Solution
A liquid discharge head design incorporating an anisotropic conductive film, resin material between the insulating cover layer and step portions, and stacked piezoelectric layers with internal electrode layers, where the step portion is recessed to accommodate the flexible printed circuit and reduce dead space, allowing for efficient mounting and minimizing warpage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the plating thickness is increased to support fine pitch wiring, then wiring strength and reliability are improved, but warping occurs due to stress and adjacent electrodes may be inadvertently connected
Solution Approach 1:
The patent applies different plating thicknesses at different locations: the first plating layer has thickness of 5-15 μm for general wiring support, while the second plating layer has reduced thickness of 3-10 μm in specific regions to prevent warping and short circuits. This local variation in plating quality resolves the contradiction between needing thick plating for reliability and thin plating to avoid warpage.
2Reliability
If the insulating cover layer is thickened to prevent short circuits, then electrical insulation is improved, but the number of available mounting portions is reduced and the FPC needs to be lengthened
Solution Approach 1:
The patent creates a stepped structure where the insulating cover layer has different heights in different regions, forming a first region and second region. This vertical dimensionality change allows the FPC to be mounted at different levels, providing multiple mounting portions without requiring the FPC to be longer, thus resolving the contradiction between insulation thickness and mounting flexibility.
3Ease of operation
If chamfering is performed on the side surface to enable FPC mounting, then ease of mounting is improved, but the structural integrity of the actuator is reduced
Solution Approach 1:
The patent segments the side surface into multiple regions: a first side surface with chamfering for FPC mounting and a second side surface without chamfering to maintain structural integrity. This segmentation allows the actuator to have both easy mounting capability and sufficient structural strength by distributing the chamfering effect to specific localized areas rather than the entire side surface.
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 design enhances mounting reliability, reduces device size, and maintains the accuracy and functionality of the piezoelectric elements by eliminating dead space and accommodating thicker insulating cover layers without compromising the piezoelectric actuator's performance.
Implementation Method 1
A piezoelectric actuator using a piezoelectric material such as lead zirconate titanate (PZT) can be used for driving a liquid discharge device such as an inkjet printer head
Data Source
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AI summary
According to one embodiment, a liquid discharge head includes a flexible printed circuit (FPC) connected to piezoelectric elements. The FPC has a first end in the first direction. A wiring layer of the FPC has a first region at the first end and a cover layer covering on a second region. The piezoelectric elements are spaced from each other in a second direction and each has a first electrode on a side surface facing towards the FPC. The first side has a joint surface facing the first region of the wiring layer. The first electrode is electrically connected to the wiring layer at the joint surface. The side surface includes a step portion that is recessed from the joint surface. A portion of the cover layer protrudes into a space adjacent to the step portion.