Stainless Steel Ground Plane Islands for Disk Drive Flexure Impedance

Solution Overview

Problem

Existing disk drive head suspensions with integrated lead or wireless flexures face a trade-off between high-performance mechanical properties and low impedance, high bandwidth electrical characteristics, as the removal of stainless steel layers to minimize mechanical impact on electrical traces leads to impedance mismatches and limited bandwidth.

Innovation Solution

The implementation of a flexure design with stainless steel ground plane islands on unsupported trace sections, which are electrically isolated from the stainless steel layer, maintains mechanical properties while enhancing trace impedance and bandwidth by minimizing contact with the gimbal and base regions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the stainless steel layer is removed from sections where traces are routed off the load beam spring region and flexure gimbal, then the mechanical properties (spring rate, pitch and roll stiffness) are improved, but the electrical performance deteriorates due to impedance mismatches

Engineering Contradiction:

Improvemechanical stiffnessVSAvoidimpedance mismatch

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by making different sections of the flexure have different stainless steel layer configurations. Specifically, the unsupported trace sections have no stainless steel layer to maintain mechanical stiffness, while supported sections have the stainless steel layer to provide electrical reference planes and improve bandwidth. This spatial differentiation resolves the contradiction between mechanical performance and electrical performance.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The flexure is segmented into distinct regions: unsupported trace sections where the stainless steel layer is removed to minimize mechanical impact, and supported sections where the stainless steel layer is retained to provide electrical reference planes. This segmentation allows each region to be optimized for its specific function, resolving the impedance mismatch problem while maintaining mechanical stiffness.

Inventive Principle:

Principle #1Segmentation

2Object-affected harmful factors

If the stainless steel layer is retained on unsupported trace sections, then the electrical bandwidth is improved through continuous reference planes, but the mechanical stiffness deteriorates due to increased trace rigidity

Engineering Contradiction:

ImprovebandwidthVSAvoidmechanical stiffness

Core Design Contradiction:

Object-affected harmful factorsVSStrength

Solution Approach 1:

The patent applies local quality by making different sections of the flexure have different stainless steel layer configurations. Specifically, the unsupported trace sections have no stainless steel layer to maintain mechanical stiffness, while supported sections have the stainless steel layer to provide electrical reference planes and improve bandwidth. This spatial differentiation resolves the contradiction between mechanical performance and electrical performance.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The supported sections act as intermediary regions that provide electrical reference planes without significantly impacting mechanical stiffness. These sections serve as a transition zone that maintains electrical continuity while the unsupported sections maintain mechanical flexibility, effectively mediating between electrical and mechanical requirements.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Strength

If traces are routed off the spring arms and gimbal, then the mechanical performance is improved, but the electrical impedance increases due to unsupported trace sections

Engineering Contradiction:

Improvespring rateVSAvoidimpedance

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by making different sections of the flexure have different stainless steel layer configurations. Specifically, the unsupported trace sections have no stainless steel layer to maintain mechanical stiffness, while supported sections have the stainless steel layer to provide electrical reference planes and improve bandwidth. This spatial differentiation resolves the contradiction between mechanical performance and electrical performance.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The flexure is segmented into distinct regions: unsupported trace sections where the stainless steel layer is removed to minimize mechanical impact, and supported sections where the stainless steel layer is retained to provide electrical reference planes. This segmentation allows each region to be optimized for its specific function, resolving the impedance mismatch problem while maintaining mechanical stiffness.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS8416532B1Continuous stainless steel ground plane flexure for a disk drive head suspension

Publication Date: 2013.04.09 HUTCHINSON TECH INC

AI summary

An integrated lead flexure comprising a base region, a gimbal extending from the base region and conductive traces. The gimbal includes spring arms and a slider mounting region extending from the spring arms. The conductive traces include one or more unsupported trace sections extending from head bond pads on the slider mounting region to the base region off of the spring arms. One or more metal islands on the unsupported trace sections enhance the impedance characteristics of traces. An insulating layer is located between the traces and the metal islands.