Flexure Terminal Pad Plating for Hard Disk Drive Reliability
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Solution Overview
Problem
In hard disk drives, the connection between the terminals of a slider and a head suspension is prone to failure due to insufficient bonding material, especially with the downsizing of terminals and the use of smaller solder balls or conductive paste, leading to unreliable connections.
Innovation Solution
A terminal pad with a base plating and a padding plating made of the same material, integrated and swelling to reduce the distance between connected portions, formed using a plating process without a mask or with a partial mask, ensuring a secure connection even with reduced bonding material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the terminals are downsized to increase recording density, then the terminal size is reduced, but the connection reliability deteriorates due to insufficient bonding material
Solution Approach 1:
The patent extends the terminal pad structure from a single-layer planar configuration to a multi-layer three-dimensional structure by adding a first plating layer, second plating layer, and third plating layer at different heights. This vertical dimensionality increase provides additional bonding surface area without increasing the horizontal footprint, thereby maintaining connection reliability while accommodating downsized terminals for higher recording density.
Solution Approach 2:
The patent implements a nested structure where the first plating layer, second plating layer, and third plating layer are concentrically arranged with each layer extending beyond the previous one. This nested configuration maximizes the use of vertical space and creates multiple overlapping bonding surfaces, ensuring sufficient bonding material contact area even when the overall terminal size is reduced.
2Quantity of substance
If smaller solder balls are used to match downsized terminals, then the solder ball size is reduced, but the fillet formation quality deteriorates
Solution Approach 1:
The multi-layer plating structure provides extended vertical bonding surfaces that compensate for the reduced horizontal contact area of smaller solder balls. The first, second, and third plating layers create multiple bonding interfaces at different heights, ensuring that sufficient fillet material is available and properly formed even when using smaller solder balls matching the downsized terminals.
3Loss of substance
If the used amount of bonding material is reduced, then the material consumption is decreased, but the connection stability deteriorates
Solution Approach 1:
By transitioning from a single-layer to a multi-layer plating structure, the patent distributes the bonding function across multiple layers at different heights. This vertical distribution allows for more efficient use of bonding material, as each layer contributes to the overall connection stability, thereby maintaining robust connections while potentially reducing the total amount of bonding material required compared to a single-layer design.
Solution Approach 2:
The patent creates a composite plating structure with multiple layers (first plating layer, second plating layer, third plating layer) that function together as an integrated bonding system. This composite structure provides enhanced connection stability through the synergistic effect of multiple layers, ensuring reliable connections even when the overall bonding material quantity is reduced.
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
The solution effectively prevents connection failures by forming a sufficient fillet between terminals, maintaining reliability even with smaller solder balls or reduced conductive paste, enhancing the connection stability and accuracy.
Implementation Method 1
a base plating formed on a surface of the terminal body and having an uniform thickness, a padding plating made of a same material as the base plating and integrated with the base plating so that the padding plating swells with respect to the base plating
Data Source
AI summary
A terminal pad of a flexure for a head suspension connected to a functional part through a bonding material includes a terminal body, a base plating formed on a surface of the terminal body and having an uniform thickness, a padding plating made of a same material as the base plating and integrated with the base plating so that the padding plating swells with respect to the base plating, and a surface plating formed on a surface of the padding plating.