Suspension Substrate Adhesive Overflow Containment

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Solution Overview

Problem

In hard disk drives, the use of conductive adhesive to connect actuator elements to the suspension substrate can lead to short circuits due to overflow, especially when the terminal part is near a load beam, causing electrical connections between electrodes to malfunction.

Innovation Solution

The suspension substrate design includes a connection structure region with a metallic support layer positioned outside the insulating and wiring layers, a protective layer inside the metallic support layer, and a through hole with gold plating for the wiring connection section, allowing visual confirmation of the adhesive overflow and preventing short circuits by ensuring the adhesive does not reach adjacent metallic structures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a liquid conductive adhesive is injected into a through hole to connect the piezoelectric element to the terminal part, then electrical connection between the electrode and wiring section is achieved, but the conductive adhesive may overflow from the liquid stopper and reach the load beam, causing short circuit between electrodes

Engineering Contradiction:

Improveelectrical connection reliabilityVSAvoidshort circuit risk from adhesive overflow

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces a recess structure as an intermediary containment zone between the liquid stopper and the load beam. This recess acts as a mediator that captures any adhesive overflow before it can reach the load beam and cause short circuits, while still allowing proper electrical connection to be formed

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The recess is designed in advance to provide a cushioning zone that prevents harmful effects. By creating this containment structure beforehand, the patent ensures that even if adhesive overflow occurs during the bonding process, the overflow will be contained within the recess and cannot reach the load beam to cause short circuits

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Area of stationary object

If the terminal part is located in the vicinity of the load beam to save space, then device compactness is improved, but the risk of short circuit increases when conductive adhesive overflows

Engineering Contradiction:

Improvesubstrate area utilizationVSAvoidshort circuit hazard from adhesive

Core Design Contradiction:

Area of stationary objectVSObject-affected harmful factors

Solution Approach 1:

The patent segments the connection structure into distinct functional zones: the liquid stopper defines the primary bonding area, the recess provides a containment zone for potential overflow, and the load beam position is separated from direct exposure to adhesive. This segmentation allows compact layout while maintaining safety through spatial zoning

Inventive Principle:

Principle #1Segmentation

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 design effectively prevents short circuits between actuator element electrodes by visually confirming the adhesive overflow and containing it within the connection structure region, ensuring reliable electrical connections and preventing malfunctions.

Implementation Method 1

a conductive adhesive is injected into a through hole, thereby the piezoelectric element can be joined to the terminal part, as well as the electrode of the piezoelectric element located on the side of the suspension substrate can be electrically connected with the wiring section

Methodology Applied

Scientific EffectConductive adhesive bonding: Conduction (electrical)

Implementation Method 2

the PZT micro-actuator is composed of a piezoelectric element composed of a lead titanate zirconate (PZT) and configured to be expanded and contracted with application of a voltage

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentUS8921707B2Suspension substrate, suspension, head suspension, and hard disk drive

Publication Date: 2014.12.30 DAI NIPPON PRINTING CO LTD

AI summary

A suspension substrate according to the present invention includes an insulating layer and a metallic support layer provided on the actuator element's side of the insulating layer. On the other side of the insulating layer, a wiring layer is provided. This wiring layer includes a plurality of wirings and a wiring connection section that can be electrically connected with the actuator element via a conductive adhesive. The outer periphery of the metallic support layer in a connection structure region is positioned outside relative to the outer periphery of the insulating layer and the outer periphery of the wiring connection section of the wiring layer.