Head Suspension Wiring Member Insulation for Short-Circuit Prevention
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Solution Overview
Problem
Existing head suspension assemblies in disk devices face issues with short-circuits between electrodes of piezoelectric elements and conductive adhesives, which compromise the reliability of electrical connections.
Innovation Solution
The design incorporates a wiring member with a metal layer, base insulating layer, conductive layer, and cover insulating layer, featuring pad openings and recessed regions to secure a gap margin between the conductive adhesive and electrodes, preventing short-circuits and enhancing electrical connection reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conductive adhesive is used to connect the piezoelectric element electrode to the conductor pattern, then electrical connection is achieved, but short-circuit between electrode and conductive adhesive occurs
Solution Approach 1:
An insulating layer is introduced as an intermediary between the conductive adhesive and the piezoelectric element electrode. This insulating layer prevents direct contact and short-circuit between the conductive adhesive and the electrode, while still allowing electrical connection to be achieved through the conductive adhesive to the conductor pattern. The insulating layer acts as a mediator that eliminates the harmful short-circuit effect while preserving the useful electrical connection function.
Solution Approach 2:
The wiring member is segmented into multiple functional layers: a base insulating layer, a conductive layer, and a cover insulating layer. The conductive adhesive is positioned between the base insulating layer and the piezoelectric element electrode, with the cover insulating layer providing additional insulation. This segmentation separates the conductive and insulating functions into distinct layers, preventing short-circuit while maintaining electrical connection reliability.
2Reliability
If the conductive adhesive is positioned close to the electrode for good electrical connection, then connection reliability improves, but the risk of short-circuit increases
Solution Approach 1:
The insulating layer serves as a mediator that allows the conductive adhesive to be positioned close to the electrode for good electrical connection while simultaneously preventing short-circuit. The insulating layer is positioned between the conductive adhesive and the electrode, enabling close proximity for effective electrical connection without direct contact that would cause short-circuit.
Solution Approach 2:
The wiring member structure provides different local qualities at different positions: the base insulating layer and cover insulating layer provide electrical insulation, while the conductive layer provides electrical conductivity. The conductive adhesive is positioned in a specific region where it can achieve good electrical connection to the conductor pattern while the surrounding insulating layers prevent short-circuit to the electrode.
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 effectively prevents short-circuits between the piezoelectric element electrodes and conductive adhesive, thereby improving the reliability of electrical connections and ensuring stable operation of the head suspension assembly and disk device.
Implementation Method 1
A head suspension assembly of one type has a piezoelectric element as a microactuator
Implementation Method 2
An electrode of the piezoelectric element is electrically and physically connected to a conductor pattern of the flexure, such as a conductive pad, using a conductive adhesive
Data Source
AI summary
A head suspension assembly includes a support plate, a wiring member on the support plate, a head mounted on the wiring member and electrically connected to the wiring member, and a piezoelectric element mounted on the wiring member. The piezoelectric element has first and second electrodes electrically connected to the wiring member. The wiring member includes a metal layer, a base insulating layer, a conductive layer, and a cover insulating layer stacked in order. The cover insulating layer includes a pad opening through which the first electrode is connected to the conductive layer with a conducive adhesive therebetween. The base insulating layer includes a first region below the first pad opening and a second region below a side surface of the piezoelectric element. A thickness of the base insulating layer in the second region is less than a thickness of the base insulating layer in the first region.