Hard Disk Drive Flexure Plasma Treatment for Low-Resistance Adhesion
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Solution Overview
Problem
As flexible circuits in hard disk drives become smaller, ensuring low-resistance electrical connections and good adhesion between conductive and insulative layers becomes increasingly challenging due to smaller feature sizes and contamination issues.
Innovation Solution
The use of atmospheric plasma and ion beams to treat the surfaces of flexible circuits, removing contaminants, forming seed layers, and depositing conductive traces, while also functionalizing dielectric polymer layers to enhance adhesion and reduce defects in electrical connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If flexures become smaller to achieve higher-density disk drives, then disk drive density increases, but electrical connection quality and adhesion between layers deteriorate
Solution Approach 1:
The patent applies preliminary plasma treatment to the metal substrate surface before depositing the dielectric layer and subsequent conductive traces. This preliminary cleaning and activation of the surface ensures low-resistance electrical connections are established early in the manufacturing process, preventing connection defects even as flexure features are scaled down to achieve higher disk drive density.
Solution Approach 2:
The patent utilizes plasma treatment to fundamentally change the surface parameters of the metal substrate, including surface energy, roughness, and chemical composition. These parameter changes enable reliable adhesion and electrical connection in smaller flexures by creating an optimized surface state that compensates for the challenges of reduced feature sizes.
2Length of moving object
If feature sizes are reduced to achieve smaller flexures, then flexure size decreases, but adhesion between conductive and insulative layers deteriorates
Solution Approach 1:
Plasma treatment is applied to the metal substrate surface before dielectric layer deposition to preliminarily enhance surface adhesion properties. This preliminary action creates a surface that promotes strong bonding between the metal substrate and dielectric layer, ensuring layer adhesion remains robust even when flexure dimensions are reduced.
Solution Approach 2:
The plasma treatment process changes critical surface parameters including surface energy, wettability, and chemical composition. These parameter changes create an optimized surface state that enhances adhesion strength between layers, allowing smaller flexures to maintain reliable inter-layer bonding despite reduced feature sizes.
3Device complexity
If conventional plasma treatments are used, then manufacturing process is simple, but electrical connection resistance is high and adhesion is poor
Solution Approach 1:
The patent employs specific plasma treatment parameters including power levels, gas composition, treatment duration, and atmospheric pressure conditions to fundamentally change the surface properties of the metal substrate. These controlled parameter changes achieve low-resistance electrical connections and strong adhesion while maintaining a relatively simple manufacturing process that can be integrated into existing production lines.
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 significantly reduces defective ground feature rates, improves electrical resistance, and increases peel strength, making it effective for producing reliable and durable flexible circuits in smaller formats.
Implementation Method 1
treating the exposed portion of the surface of the metal substrate with the atmospheric plasma to remove contaminants from the exposed portion of the metal substrate
Implementation Method 2
The atmospheric plasma functionalizes the surface of the dielectric polymer layer
Implementation Method 3
depositing a seed layer on the dielectric polymer layer and the treated surface of the metal substrate
Implementation Method 4
electroplating a conductive metal onto portions of the seed layer not covered by the photo resist layer to form a plurality of conductive traces
Implementation Method 5
the atmospheric plasma removes conductive contaminants from the exposed portion of the surface of the dielectric polymer layer between adjacent conductive traces
Data Source
AI summary
Methods for producing flexible circuits can include creating treating a surface of the flexible circuit with at least one of an atmospheric plasma and a beam of ions. The atmospheric plasma is formed by directing a flow of gas between an electrode and the surface of the flexible circuit and generating a voltage between the electrode and the flexible circuit to create a plasma from the gas. A mean ion energy of the ions in the ion beam ranges from about 500 electron volts to about 1,500 electron volts.