Interleaved Conductor Structure for Hard Disk Drive Signal Integrity
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Solution Overview
Problem
In hard disk drives, the intrinsic stiffness of conductor wires connected to the head slider causes unwanted signal losses, reflections, and inefficiencies due to high signal rates and mutual coupling with conductive stainless steel flexures, affecting read/write head performance.
Innovation Solution
An interleaved conductor structure with alternating widths and phases of electrical traces, along with insulation layers and a conductive underlayer, is used to reduce signal loss and increase characteristic impedance range, providing better interference shielding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conductor traces are positioned close to the conductive stainless steel flexure structure, then electrical interconnection is achieved, but signal losses and reflections increase due to mutual coupling and inductance
Solution Approach 1:
The patent transitions from a planar trace layout to a three-dimensional interleaved structure where conductor traces on different layers are offset from each other. This vertical stacking with lateral offset creates spatial separation that reduces mutual coupling and inductance while maintaining electrical connectivity through the insulating layer structure.
Solution Approach 2:
The patent introduces an insulating layer structure as an intermediary between the conductor traces and the conductive stainless steel flexure. This intermediate layer acts as a barrier that reduces direct electromagnetic coupling and mutual inductance between adjacent traces, thereby reducing signal losses while still allowing electrical interconnection.
2Power
If conductor trace width is increased, then signal transfer capability is improved, but characteristic impedance control becomes more difficult
Solution Approach 1:
The patent divides the conductor trace system into multiple segments across different layers, with each layer containing traces of specific widths optimized for their function. The interleaved structure allows different trace segments to have different impedance characteristics, enabling better overall impedance control while maintaining signal transfer capability.
Solution Approach 2:
The patent varies the width parameter of conductor traces across different layers and positions within the interleaved structure. By changing trace width as a parameter, the design achieves both adequate signal transfer capability (wider traces where needed) and precise characteristic impedance control (narrower traces where impedance matching is critical).
Data Source
AI summary
An interleaved conductor structure for electrically connecting the read/write electronics to a read/write head in a hard disk drive is provided. The interleaved conductor structure may allow for an increased characteristic-impedance range, greater interference shielding and a reduction of signal loss that is contributed by a lossy conductive substrate. The electrical traces may have different widths, be offset, or even wrap around each other at the via connections.