Microactuator Bonding Aperture for Complete Epoxy Cure

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

The electrical connection between the PZT microactuator and the stainless steel flexure in dual stage actuated suspensions for hard disk drives often degrades or fails due to incomplete curing of conductive epoxy, which acts as a thermal insulator, leading to grounding issues during fatigue reliability testing.

Innovation Solution

Relocating the conductive epoxy bridge for the ground connection to a position where it can receive adequate heating during the curing process, such as from the opposite side of the PZT mounting, and creating an aperture in the load beam to allow direct access for heating, ensuring complete curing of the epoxy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conductive epoxy is placed between the PZT microactuator and the stainless steel flexure to create an electrical connection, then the electrical grounding is achieved, but the epoxy acts as a thermal insulator and prevents adequate heating during curing, leading to incomplete cure and connection failure

Engineering Contradiction:

Improveelectrical connection reliabilityVSAvoidcuring temperature exposure

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The patent applies dimensionality change by creating an aperture in the load beam that allows the heating source to access the conductive epoxy from a different spatial dimension (through the aperture rather than from the side). This enables thermal energy to reach the epoxy that was previously shielded by the PZT microactuator, resolving the contradiction between maintaining electrical connection integrity and achieving adequate curing temperature.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The aperture acts as an intermediary structure that facilitates heat transfer to the conductive epoxy. By creating this opening in the load beam, the patent introduces a pathway that allows thermal energy to penetrate through to the epoxy, mediating between the heating source and the epoxy material to ensure complete curing while maintaining the electrical grounding function.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the conductive epoxy is sandwiched between the PZT and the stainless steel layer, then the electrical grounding path is established, but the epoxy cannot receive adequate heating during the curing process due to thermal insulation by the PZT and stainless steel

Engineering Contradiction:

Improvegrounding connection reliabilityVSAvoidcuring process difficulty

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent applies segmentation by dividing the load beam structure to create an aperture, effectively segmenting the otherwise continuous structure. This segmentation allows the heating process to access the conductive epoxy from a new direction, making the curing process feasible without requiring complex heating apparatus or process modifications.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of attempting to heat the epoxy from the conventional side (which is blocked by the PZT and stainless steel), the patent inverts the approach by heating through the aperture from the opposite side. This inversion of the heating direction allows thermal energy to reach the epoxy effectively, resolving the manufacturing difficulty associated with the sandwich configuration.

Inventive Principle:

Principle #13The other way round (Inversion)

3Reliability

If the PZT microactuator is mounted on the stainless steel flexure with conductive epoxy, then the electrical grounding is achieved, but the connection degrades or fails during fatigue reliability testing due to incomplete epoxy cure

Engineering Contradiction:

Improveelectrical grounding reliabilityVSAvoidconnection durability under stress

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent applies preliminary action by ensuring complete curing of the conductive epoxy before the PZT microactuator is subjected to operational stresses. By modifying the curing process to provide adequate heat exposure through the aperture, the epoxy achieves full cure strength and electrical conductivity in advance, preventing connection degradation during subsequent fatigue testing and extended operational periods.

Inventive Principle:

Principle #10Preliminary action

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 approach enhances the quality and reliability of the electrical contact, reducing the likelihood of connection failure over time and under environmental stressors like temperature cycling and vibration.

Implementation Method 1

The conductive epoxy that forms an electrically conductive bridge between the PZT's ground electrode and the stainless steel surface of the flexure

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

receiving adequate heating during the curing process

Methodology Applied

Scientific EffectConvection: Convection

Data Source

PatentUS9349398B1Microactuator bonding having increased adhesive exposure for more thorough adhesive cure

Publication Date: 2016.05.24 MAGNECOMP CORP

AI summary

In a dual stage actuated suspension, conductive adhesive is both sandwiched between a microactuator and a grounded stainless steel layer of the suspension, and also extends at least partially onto a wrap-around portion of the microactuator's ground electrode. The conductive adhesive that extends onto the wrap-around portion of the electrode has an exposed edge for more complete exposure and curing during the cure step.