Actuator Unit FPC Protrusion Bonding for Inkjet Printhead Reliability
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Solution Overview
Problem
Inkjet printheads face issues with short-circuits due to reduced solder bonding areas, leading to electrical disconnections and structural complexity, and existing solutions compromise mechanical strength or require additional components.
Innovation Solution
An electric device with an actuator unit and flexible printed circuit board (FPC) connection using protrusions and recesses on the FPC, where bonding parts cover the contact area to prevent short-circuits and maintain contact without additional structural members, simplifying the design and protecting the actuator unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the bonding area between connection pads and auxiliary electrode portions is reduced to prevent solder bump contact, then short-circuit between electrodes is prevented, but the bond strength deteriorates causing electrical disconnection
Solution Approach 1:
The patent introduces a protrusion structure on the FPC that acts as an intermediary mechanical connector. This protrusion physically engages with a corresponding recess on the printhead, providing mechanical support and maintaining contact pressure between the connection pads and auxiliary electrode portions. This allows sufficient bonding area to be maintained for electrical reliability without requiring excessive solder volume that would cause short-circuits.
2Ease of manufacture
If additional members such as elastic members and fixing members are used to press FPC against piezoelectric patches, then electrical connection is achieved without solder, but the structure becomes complex and the piezoelectric patch may be damaged
Solution Approach 1:
The patent merges the electrical connection function and mechanical support function into a single integrated structure. The protrusion on the FPC simultaneously provides mechanical engagement and maintains contact pressure for electrical connection, eliminating the need for separate elastic members and fixing members. This reduces structural complexity while achieving reliable electrical connection without solder.
3Productivity
If continuous flat piezoelectric sheets are used with high density pressure chamber array, then printing resolution and speed are improved, but bonding area between connection pads and auxiliary electrodes decreases causing short-circuit risk
Solution Approach 1:
The patent applies local quality by concentrating the bonding function at specific locations through the protrusion-recess engagement structure. Instead of relying on large-area solder bonding across the entire FPC surface, the critical electrical connections are localized to specific engagement points where the protrusion maintains contact pressure. This allows high-density pressure chamber arrays to be used for improved printing resolution while maintaining reliable electrical connections at the localized bonding points.
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 solution effectively inhibits short-circuits and reduces the need for conductive materials, simplifies the structure, and enhances mechanical strength by using a bonding part to maintain contact between the FPC and electrodes, ensuring reliable electrical connections and preventing damage to the actuator unit.
Implementation Method 1
A portion of the piezoelectric sheets, which is interposed among the individual and common electrodes and polarized in the direction of stacking of the piezoelectric sheets and common and individual electrodes, expands and contracts in the stacking direction by the piezoelectric longitudinal effect
Data Source
AI summary
There is disclosed an electric device comprising: an actuator unit which includes a plurality of electrodes formed thereon; a printed wiring board which comprises: an electrically insulating flexible layer which has on one of its opposite sides protrusions for the respective electrodes, each of the protrusions forming a corresponding recess on the other side of the flexible layer; and a plurality of electrically conducting layers disposed on the respective protrusions to be in contact with the respectively corresponding electrodes; and a plurality of bonding parts each of which is in contact with one of the conducting layers and a corresponding one of the electrodes to completely cover a contact portion between the conducting layer and the electrode so as to maintain the contact therebetween.