Recording Head Actuator Bump Connection via Resin Penetration
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Solution Overview
Problem
The existing methods for connecting a piezoelectric actuator and a printed wiring board in recording head units are costly and unreliable due to the need for high-accuracy formation of openings in the cover coat to expose terminal portions, which increases wiring density and manufacturing costs.
Innovation Solution
A method involving the formation of conductive bumps on the actuator unit that protrude to connect with terminal portions on the printed wiring board, using an uncured synthetic resin layer to facilitate reliable electrical connection without the need for precise opening formation in the cover coat, thereby reducing manufacturing costs and increasing reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the terminal portions are formed larger to account for opening formation errors, then the connection reliability is improved, but the wiring density increases and manufacturing cost increases
Solution Approach 1:
The patent introduces a resin layer as an intermediary substance between the terminal portions and the cover coat. This resin layer fills the openings and provides a bonding medium, allowing smaller terminal portions to achieve reliable connections without requiring large safety margins for opening formation errors.
Solution Approach 2:
The patent changes the physical state of the resin from uncured to cured, transforming it from a fluid that can flow into openings to a solid that provides structural support and electrical insulation. This phase change enables the resin to adapt to varying opening sizes and provide reliable bonding regardless of opening formation precision.
2Reliability
If the terminal portions are formed larger to ensure reliable connection, then the connection reliability is improved, but the spacing pitch between conductive leads decreases
Solution Approach 1:
The resin layer acts as a flexible intermediary that can accommodate misalignments and errors in opening formation. This mediation allows terminal portions to be smaller while still achieving reliable connections, thereby maintaining adequate spacing pitch between adjacent conductive leads.
3Ease of manufacture
If high accuracy opening formation is implemented to minimize terminal portion area, then the wiring density is reduced, but the manufacturing cost increases
Solution Approach 1:
The resin layer serves as a compensating intermediary that tolerates variations in opening formation accuracy. By providing a fluid bonding medium that flows into and fills openings, the resin eliminates the need for high-precision opening formation, allowing standard manufacturing processes to achieve adequate connection reliability.
Solution Approach 2:
The patent utilizes the phase change property of the resin, applying it in the uncured state to allow flow and filling of openings, then curing it to provide structural integrity. This parameter change enables the system to tolerate a wider range of opening sizes and positions without requiring high manufacturing precision.
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 method allows for a reliable and cost-effective electrical connection between the actuator unit and the printed wiring board, reducing wiring density and simplifying the manufacturing process by eliminating the need for precise opening formation, while ensuring stable ink ejection in ink-jet heads.
Implementation Method 1
bringing the plurality of conductive bumps and the terminal portions of the conductive leads into contact with one another by pressing the plurality of conductive bumps onto the uncured synthetic-resin layer such that the plurality of conductive bumps penetrate the uncured synthetic-resin layer
Implementation Method 2
curing the uncured synthetic-resin layer
Implementation Method 3
pressing the plurality of conductive bumps onto the uncured synthetic-resin layer such that the plurality of conductive bumps penetrate the uncured synthetic-resin layer
Data Source
AI summary
A method of producing a recording head unit including: (A) a recording head including: a plurality of recording elements; and an actuator unit including a plurality of individual electrodes which respectively correspond to the recording elements; and (B) a printed wiring board which includes conductive leads respectively having terminal portions, which is electrically connected to the individual electrodes, and through which an operating signal for operating the recording elements is supplied to the individual electrodes, the method including: forming a plurality of conductive bumps on a surface of the actuator unit such that the bumps protrude from the surface of the actuator unit, so as to be electrically connected to the individual electrodes, respectively; coating a surface of the printed wiring board with an uncured synthetic resin to form an uncured synthetic-resin layer covering the conductive leads of the printed wiring board; bringing the bumps and the terminal portions of the conductive leads into contact with one another by pressing the bumps onto the uncured synthetic-resin layer such that the bumps penetrate the uncured synthetic-resin layer; and curing the uncured synthetic-resin layer.