PZT Microactuator Stroke Length via Segmented Epoxy Bonding
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Solution Overview
Problem
In dual stage actuated (DSA) suspensions for disk drives, the stroke length of microactuators is reduced due to elastic deformation of adhesives used for mechanical and electrical bonding, limiting the linear expansion or contraction in response to driving voltage.
Innovation Solution
The use of additional strong adhesives like epoxy to anchor PZT microactuators to the suspension, with a combination of non-conductive and conductive adhesives to enhance the ground and driving connections, allowing for increased stroke length without inhibiting the microactuator's expansion and contraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If conventional adhesives are used to bond PZT microactuators to the suspension, then the microactuator can be mechanically and electrically connected, but the stroke length is reduced due to elastic deformation of the adhesive
Solution Approach 1:
The bonding system is segmented into multiple functional layers: a non-conductive adhesive layer for mechanical bonding and a conductive adhesive layer for electrical grounding. This segmentation allows each layer to be optimized for its specific function, with the non-conductive adhesive providing strong mechanical attachment while the conductive adhesive provides reliable electrical connection without interfering with the microactuator's stroke.
Solution Approach 2:
The invention uses composite adhesive materials - specifically combining non-conductive adhesive (for mechanical bonding) with conductive adhesive (for electrical grounding). This composite approach allows the bonding system to simultaneously achieve strong mechanical attachment and reliable electrical connection while minimizing elastic deformation that would reduce stroke length.
2Length of moving object
If additional strong adhesive is added to anchor the PZT microactuator, then the stroke length increases, but the complexity of the bonding process increases
Solution Approach 1:
The bonding process is segmented into distinct sequential steps: first applying non-conductive adhesive for mechanical bonding, then applying conductive adhesive for electrical grounding. This segmentation allows each adhesive to be applied in its optimal state and cured separately, achieving strong anchoring and reliable electrical connection without excessive process complexity.
Solution Approach 2:
The non-conductive adhesive acts as an intermediary layer between the PZT microactuator and the conductive adhesive. This intermediary provides a stable mechanical foundation that allows the conductive adhesive to be applied effectively for electrical grounding, while both layers work together to maximize stroke length through optimized anchoring.
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
The approach results in a significant increase in microactuator stroke length by approximately 0.9 nm/V, improving the positioning accuracy and reliability of the head slider over the disk surface.
Implementation Method 1
The term 'stroke' or 'stroke length' as used herein is shorthand for the amount of linear expansion or contraction of the portion of the suspension moved by the microactuator in response to a given amount of input driving voltage to the microactuator. For PZT microactuators, stroke is usually expressed in nm/V.
Implementation Method 2
The ground connection is made by a dispensation or mass of electrically conductive adhesive that bridges a first gap between the top and generally horizontal face of the PZT device and an electrical ground top portion of the suspension
Implementation Method 3
The microactuator is mounted to the proximal portion and to the distal portion via first and second dispensations or masses of non-conductive adhesive
Data Source
AI summary
In a dual stage actuated (DSA) suspension, a PZT microactuator is electrically and mechanically bonded to the rest of the suspension by non-conductive epoxy on the front and rear bottom faces of the PZT, by conductive epoxy that bridges a gap between the top face of the PZT which defines the ground electrode and an adjacent metallic and grounded portion of the suspension, and further by additional non-conductive epoxy that bridges the gap and which at least partly overlies the conductive epoxy. The additional non-conductive epoxy increases the effective stroke length of the PZT.