Vibration Actuator PCB Bonding Stress Reduction
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Solution Overview
Problem
The concentration of stress on the electromechanical transducer in vibration-type actuators can lead to breakage when a flexible printed circuit board is bonded using adhesives or anisotropic conductive films, due to the creation of spaces between the transducer and protrusions, causing uneven pressure distribution.
Innovation Solution
The flexible printed circuit board is positioned such that no end portion overlaps with the internal spaces of the protrusions in a direction perpendicular to the elastic body's surface, reducing stress concentration on the electromechanical transducer by ensuring pressure is applied outside these spaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a flexible printed circuit board is bonded to the electromechanical transducer using adhesive or anisotropic conductive film, then power can be fed to the vibration-type actuator, but stress concentration occurs on the transducer due to spaces between the transducer and protrusions, causing breakage
Solution Approach 1:
The patent introduces a filler material as an intermediary substance placed in the spaces between the electromechanical transducer and the protrusions. This filler material serves as a mediator that transmits bonding pressure uniformly across the transducer surface, preventing stress concentration while still allowing the flexible printed circuit board to be bonded effectively. The filler material fills the gaps without being compressed excessively, thereby protecting the transducer from breakage during the bonding process.
2Manufacturing precision
If pressure is applied to bond the flexible printed circuit board to achieve conduction and predetermined thickness, then proper electrical connection is established, but the pressure may cause breakage of the electromechanical transducer due to uneven distribution
Solution Approach 1:
The filler material acts as a pressure-distributing intermediary between the bonding pressure and the electromechanical transducer. It receives the applied pressure and redistributes it uniformly across its surface and the transducer, preventing localized stress concentration that would cause breakage. This allows proper bonding quality to be achieved while protecting transducer integrity.
Solution Approach 2:
The patent changes the physical parameters of the bonding interface by introducing a material with specific compressibility and pressure-distributing properties. The filler material's parameters (compressibility, hardness, distribution characteristics) are selected to optimize pressure distribution, transforming the bonding process from one that concentrates stress to one that distributes stress uniformly, thereby preventing transducer breakage while maintaining bonding quality.
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 configuration stabilizes the manufacturing process by reducing the likelihood of electromechanical transducer breakage and ensures stable operation of the vibration-type actuator.
Implementation Method 1
a piezoelectric element 3 attached to one surface of the elastic body 2
Implementation Method 2
The protrusions 21 are brought into pressure contact with the slider 5... the slider 5 can be moved relative to the elastic body 2
Data Source
AI summary
The present invention provides a vibration-type actuator that makes it possible to improve and stabilize yields.A vibration-type actuator includes a vibrator including an elastic body with a protrusion having a contact portion, and an electromechanical transducer attached to a surface of the elastic body; and a flexible printed circuit board having an electrode portion and attached to the electromechanical transducer. There is a space between the contact portion and the electromechanical transducer. No end portion of the electrode portion of the flexible printed circuit board is overlapped with the space in a direction perpendicular to the surface of the elastic body.