Comb Structure Piezoelectric Microactuator for Disk Drive Suspension
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Solution Overview
Problem
Conventional PZT microactuators for disk drive suspensions are complex to integrate mechanically and electrically, requiring numerous steps and thermal curing that can impact performance, and they often have porous sawn edges prone to particle shedding, which can damage data disks.
Innovation Solution
A PZT microactuator assembly with a comb structure operating in the d33 mode, featuring electrodes on the same horizontal level, simplifying electrical connections and integration, using a single vertical layer of PZT material, and sintering with electrodes in place to reduce adhesives and enhance characteristics, allowing for greater stroke length and precise mass control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional PZT microactuators use top and bottom electrodes with vertical stacking, then the device can operate in d31 mode, but the electrical connections become complex and integration requires numerous steps
Solution Approach 1:
The patent transitions from vertical stacking (d31 mode with top and bottom electrodes) to a planar comb structure where all electrodes are arranged horizontally in interdigitated fingers. This dimensional reconfiguration places all electrical connections on the same level, eliminating the need for complex through-layer routing and simplifying integration while maintaining d33 mode operation.
Solution Approach 2:
The patent divides the electrode structure into multiple interdigitated fingers rather than using single top and bottom electrodes. This segmentation creates multiple parallel electrical pathways in the planar direction, enabling simplified connections while achieving the desired actuation through d33 mode expansion across all finger gaps simultaneously.
2Strength
If conventional PZT microactuators use thermal curing of adhesives for integration, then mechanical bonding is achieved, but PZT performance degrades when cure temperature approaches Curie temperature
Solution Approach 1:
The patent combines the PZT material deposition and electrode formation into a single co-sintering process. The PZT slurry is applied over the electrode pattern, and both are sintered together in one thermal cycle, eliminating the need for separate adhesive bonding steps and avoiding exposure to temperatures that would degrade PZT performance.
Solution Approach 2:
The patent replaces mechanical adhesive bonding with direct ceramic bonding through co-sintering. Instead of using organic adhesives that require thermal curing, the PZT material is sintered directly onto the electrode substrate, creating a strong mechanical bond without exposing the PZT to degradation temperatures.
3Manufacturing precision
If conventional PZT microactuators use sawn edges for shaping, then precise dimensions are achieved, but porous edges prone to particle shedding are created
Solution Approach 1:
The patent performs the final shaping and densification of the PZT material during the sintering process itself, before the device is removed from the substrate. The co-sintering process densifies the PZT ceramic and seals the edges, preventing particle shedding while achieving precise dimensions through controlled sintering parameters.
Solution Approach 2:
The patent uses controlled sintering parameters (temperature, time, atmosphere) to transform the PZT slurry into a dense ceramic structure with sealed edges. By optimizing these parameters, the process achieves both precise dimensional control and elimination of porous structures that would cause particle shedding.
4Ease of manufacture
If conventional PZT microactuators require multiple applications of conductive and structural adhesives, then electrical and mechanical connections are established, but the number of process steps increases to 52
Solution Approach 1:
The patent merges multiple separate processes (electrode fabrication, PZT material application, structural bonding, and electrical connection) into a single co-sintering operation. The electrode pattern and PZT slurry are applied together, and both are sintered in one thermal cycle, reducing the process from 52 steps to a manageable number of key steps.
Solution Approach 2:
The co-sintering process performs multiple functions simultaneously: it bonds the PZT material to the substrate, establishes electrical connections through the electrode pattern, and densifies the PZT ceramic structure. This multi-functional approach eliminates the need for separate adhesive applications and curing steps.
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 solution reduces assembly steps, minimizes adhesive use, prevents particle shedding, and achieves higher stroke length per unit voltage with enhanced characteristics, improving integration and performance in disk drive suspensions.
Implementation Method 1
When an actuating voltage is applied to the PZT, the PZT expands and contracts lengthwise in the d31 mode of the piezoelectric material
Implementation Method 2
sintering with electrodes in place to reduce adhesives and enhance characteristics
Data Source
AI summary
A microactuator assembly is formed by depositing PZT material over electrode gaps, the electrode gaps being defined by the spaces between interleaved fingers of metal that define alternating plus and minus electrodes. The PZT material is hardened and poled. The PZT material may be deposited and poled either as isolated islands of PZT material across respective electrode gaps, or as a continuous sheet of PZT material with localized areas of that material being poled and then activated. The individual PZT elements are arranged such that successive PZT elements extend in the same direction as across the electrode gaps. The resulting microactuator assembly acts in the d33 direction of the PZT elements. The electrodes have raised or recessed features such as ribs or castellations, with the PZT material mating with those features, thus anchoring the PZT material to the electrodes.