Disk Drive Flexure Tail Noble Metal Layer Testing
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Solution Overview
Problem
Current head suspension assembly flexure tail designs require extra processing steps for reliable electrical connections during dynamic electrical testing, necessitating enlarged testing pads that need to be cut away, and lack a straightforward method for making a reliable ground connection without additional processing.
Innovation Solution
The flexure tail terminal region is designed with a configuration that includes a structural layer, a conductive layer, and a dielectric layer, featuring aligned bond pads for secure bonding with the FPC, and optional noble metal testing pads and a grounding pad for reliable temporary connections, allowing for efficient electrical testing without extra processing steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If enlarged testing pads are added to facilitate dynamic electrical testing, then testing reliability is improved, but device complexity and processing steps increase
Solution Approach 1:
The noble metal layer is designed to serve multiple functions: it provides reliable bonding surfaces for FPC connection, enables dynamic electrical testing through integrated testing pads, and establishes ground connections. This multi-functionality eliminates the need for separate enlarged testing pads that would require additional processing steps.
Solution Approach 2:
The testing pads are merged with the bonding pads by using the same noble metal layer for both purposes. The bond pad backing islands serve dual roles as both bonding surfaces and testing contact points, consolidating what would traditionally be separate features into a unified structure.
2Reliability
If ground connection features are added to the flexure tail, then ground connection reliability is improved, but manufacturing complexity increases
Solution Approach 1:
The ground connection feature is merged with the existing bond pad structure. The noble metal layer that forms the bonding surface also creates the ground connection path through its conductive properties, eliminating the need for separate ground connection features.
Solution Approach 2:
The noble metal layer performs multiple functions simultaneously: it provides mechanical bonding support, enables electrical signal transmission, and establishes ground connections. This multi-functionality reduces manufacturing complexity by eliminating the need for separate ground connection processing steps.
3Reliability
If noble metal layer is deposited on bond pad backing islands, then bonding reliability and testing capability are improved, but manufacturing steps increase
Solution Approach 1:
The noble metal layer deposition process is designed to simultaneously achieve multiple objectives: it creates reliable bonding surfaces for FPC attachment, forms integrated testing pads for dynamic electrical testing, and establishes ground connection paths. This multi-functionality offsets the added manufacturing step by eliminating the need for separate enlarged testing pad features.
Solution Approach 2:
The noble metal layer is selectively deposited only on the bond pad backing islands in the terminal region of the flexure tail, rather than throughout the entire flexure. This localized deposition provides the necessary bonding and testing reliability where needed while minimizing additional manufacturing complexity.
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 design facilitates reliable electrical connections and ground connections during testing without the need for extra processing steps, enhancing the efficiency of the head stack assembly process and ensuring consistent performance.
Implementation Method 1
a noble metal layer comprising testing pads (552, 554) is disposed on the plurality of bond pad backing islands (512, 514)... The noble metal layer also includes a grounding pad (556) deposited on the structural layer (510) in the adjacent area (570)
Data Source
AI summary
A head suspension assembly for a disk drive includes a load beam and a laminated flexure that comprises a stainless steel layer, a copper trace layer, and a dielectric layer between the stainless steel layer and the copper trace layer. The laminated flexure includes a flexure tail that extends away from the load beam to a flexure tail terminal region. The copper trace layer includes a plurality of flexure bond pads in the flexure tail terminal region. The stainless steel layer includes a plurality of backing islands in the flexure tail terminal region. Each of the plurality of backing islands is aligned with a corresponding one of the plurality of flexure bond pads. A noble metal layer is disposed on the plurality of backing islands.