Flexible Cable Trace Density via Vertical Stacking
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Modern magnetic hard disk drives face challenges in accommodating an increasing number of conductive traces on flexible cables due to size constraints and the need for additional structures and functions in head gimbal assemblies, limiting the number of electrical paths and connections to integrated circuit chips.
Innovation Solution
The solution involves a flexible laminar cable design that uses a combination of subtractive and additive processes to define and deposit conductive traces, allowing for a higher density of electrical paths with reduced spacing and width, enabling more traces to be integrated in the distal region of the cable, which is reinforced with a metallic stiffener and includes an insulative cover layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the number of conductive traces on the flexible cable is increased to accommodate additional HGA structures and functions, then the functionality and electrical connectivity of the disk drive is improved, but the available space on the flexible cable is exhausted due to width limitations imposed by disk drive height constraints
Solution Approach 1:
The patent transitions from traditional planar trace routing to a three-dimensional vertical stacking architecture. Multiple conductive traces are arranged in vertical layers (first plurality on first side, second plurality on second side) separated by a dielectric layer, enabling increased trace density without increasing cable width. This dimensional transition allows the flexible cable to accommodate more conductive paths while maintaining the same footprint constraints.
2Productivity
If the flexible cable width is increased to accommodate more conductive traces, then the number of electrical paths is improved, but the disk drive height is exceeded
Solution Approach 1:
The invention moves the expansion direction from horizontal (width) to vertical (thickness). By stacking conductive traces in multiple layers separated by a dielectric layer, the cable achieves higher electrical path capacity without increasing the lateral dimensions that would exceed disk drive height constraints.
Solution Approach 2:
The flexible cable employs a composite laminar structure consisting of multiple dielectric layers, conductive trace layers, and reinforcing stiffener layers. This composite architecture enables high-density trace routing while maintaining mechanical flexibility and structural integrity within the height constraints of the disk drive.
3Productivity
If conductive traces are placed closer together to increase trace density, then the number of traces per unit area is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The dielectric layer is deposited and patterned beforehand to establish precise spacing guidelines before the conductive traces are formed. This preliminary structuring of the dielectric layer with defined thickness and pattern features provides a template that guides subsequent trace formation, ensuring consistent spacing and reducing manufacturing variability.
Solution Approach 2:
The use of laminar dielectric layers with controlled thickness provides a physical template that defines trace spacing. The dielectric material acts as a spacer and structural guide, making the trace spacing dependent on the dielectric layer dimensions rather than direct trace placement, thereby reducing manufacturing precision requirements.
Data Source
AI summary
A novel method to manufacture a flexible cable for a disk drive is disclosed. The method includes providing a flexible laminar sheet. The flexible laminar sheet has a dielectric substrate layer and an electrically conductive layer contacting a first side of the dielectric substrate layer. A portion of the electrically conductive layer is etched away to define a first plurality of electrically conductive traces and to expose an etched surface of the first side of the dielectric substrate layer. A second plurality of electrically conductive traces is deposited on the etched surface of the first side of the dielectric substrate layer.