Piezoelectric Actuator Electrical Connection via Through-Hole Adhesive Injection
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Solution Overview
Problem
Existing methods for connecting piezoelectric elements in head suspensions face challenges in ensuring reliable electrical connections without damaging the elements, as wire bonding can cause stress and reduce bonding strength, while conductive adhesives may lead to clearance issues and short circuits.
Innovation Solution
A through hole is formed through the piezoelectric element from one end face to the opposite end face, allowing for the injection of a liquid conductive adhesive to connect the electrode to a terminal, ensuring secure and reliable electrical connections without stress or clearance problems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wire bonding is used to connect the piezoelectric element, then electrical connection is achieved, but the piezoelectric element may crack due to local stress
Solution Approach 1:
A conductive adhesive is introduced as an intermediary material between the piezoelectric element and the terminal. This adhesive distributes the bonding stress over a larger area rather than concentrating it at a single wire bonding point, thereby preventing cracks while maintaining reliable electrical connection. The adhesive layer acts as a stress-distributing medium that protects the fragile piezoelectric element.
2Reliability
If conductive adhesive is used to connect the piezoelectric element, then electrical connection is achieved, but swell protrusion or terminal inclination occurs causing clearance insufficiency
Solution Approach 1:
A through-hole is formed in advance through the piezoelectric element before applying the conductive adhesive. This through-hole serves as a pre-prepared cavity that guides and confines the adhesive flow, preventing unwanted swell protrusion. The preliminary creation of this structural feature ensures that subsequent adhesive application will not cause clearance issues or terminal inclination.
Solution Approach 2:
The conductive adhesive is applied locally within the confines of the through-hole rather than being freely distributed. This localized application ensures that the adhesive fills only the necessary space for electrical connection without protruding into areas where it would cause clearance problems or terminal misalignment.
3Object-affected harmful factors
If wire bonding is used to connect the piezoelectric element, then electrical connection is achieved, but bonding strength is insufficient when applied force is reduced to prevent cracking
Solution Approach 1:
The conductive adhesive serves as a mediator that provides both electrical conductivity and mechanical bonding strength. Unlike wire bonding which requires high localized force, the adhesive distributes bonding forces across a larger interface area, achieving sufficient strength without applying damaging concentrated stress to the piezoelectric element.
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 provides a reliable and durable electrical connection between the piezoelectric element and terminal, preventing damage and ensuring precise positioning of magnetic heads in magnetic disk drives, while allowing for easy automation of adhesive injection and preventing short circuits.
Implementation Method 1
a piezoelectric element (13) which is arranged between a base plate (33) and a load beam (35) and which minutely moves a front end of the load beam in a sway direction when deformed with an applied voltage
Implementation Method 2
a conductive adhesive is injected into the through hole to join the electrode and terminal together
Data Source
AI summary
An electrical connecting structure for a piezoelectric element enables wiring to the piezoelectric element to be carried out without deteriorating the productivity and reliability of the piezoelectric element. The electrical connecting structure is formed by facing a common electrode of the piezoelectric element to a terminal that supplies power to the common electrode and by injecting a conductive adhesive into a through hole, which is formed substantially at the center of the piezoelectric element, from an opening of the through hole that is on the opposite side of the common electrode, thereby securing electrical connection between the terminal and the common electrode of the piezoelectric element.