HDD Flexure Tongue Gaps Prevent Electrical Shorts

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Solution Overview

Problem

In hard disk drives, the assembly of microactuators with flexure support structures often results in undesirable electrical shorts due to mechanical and electrical coupling, which affects manufacturing yield and areal density improvements.

Innovation Solution

A flexure gimbal assembly with a conductive layer and insulating layer featuring a flexure tongue with gaps or voids to prevent contact between conductive adhesive and the conductive layer, along with an electrically conductive adhesive of viscosity 10 Pa-s to 60 Pa-s to ensure a tight bond without overflow.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If microactuators are mechanically and electrically coupled to flexure support structure using conductive adhesive, then precise head positioning is achieved, but electrical shorts occur reducing manufacturing yield

Engineering Contradiction:

Improvehead positioning precisionVSAvoidmanufacturing yield

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The flexure support structure is segmented into electrically isolated regions using insulating layers and discontinuous conductive patterns. This segmentation prevents electrical shorts while maintaining mechanical coupling functionality, thereby improving manufacturing yield without compromising head positioning precision.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

An insulating layer is introduced as an intermediary between the conductive adhesive and the flexure support structure's conductive elements. This intermediary prevents direct electrical contact that causes shorts while allowing the conductive adhesive to maintain mechanical bonding, thus resolving the contradiction between electrical isolation and mechanical coupling.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Strength

If conductive adhesive is applied to attach microactuator to flexure tongue, then mechanical bonding is achieved, but adhesive overflow contacts conductive layer causing electrical shorts

Engineering Contradiction:

Improvebond strengthVSAvoidelectrical short risk

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The flexure tongue is pre-configured with an insulating layer and defined conductive patterns before adhesive application. This preliminary preparation creates controlled zones that guide adhesive placement, ensuring strong bonding while preventing overflow onto conductive elements that would cause electrical shorts.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The flexure tongue exhibits local quality variations with insulating regions and conductive regions in specific locations. The insulating areas are strategically positioned to receive and contain the conductive adhesive, while conductive areas are protected from adhesive contact, thus achieving both strong bonding and electrical isolation.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS9218834B2Dual stage microactuator flexure feature for minimizing electrical shorts

Publication Date: 2015.12.22 WESTERN DIGITAL TECHNOLOGIES INC

AI summary

Approaches to a flexure gimbal assembly for a hard-disk drive (HDD), having a feature for reducing the risk of electrical shorts, include a flexure having an electrically conductive layer and an insulating layer having a flexure tongue with which one or more microactuator piezo actuating device is coupled, where the flexure tongue comprises a gap positioned to inhibit contact between the conductive adhesive and the conductive layer of the flexure which may otherwise cause an electrical short.