Head Suspension Assembly with Reinforced LDU Connection Terminals
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Solution Overview
Problem
The connection terminals for the laser diode unit (LDU) in hard disk drives (HDDs) are not rigid enough, leading to bending and instability in the connection terminal and connection pad distance during solder bonding, which can result in poor bonding yield and potential cracks due to shocks or heat cycles.
Innovation Solution
A head suspension assembly design that includes a cover layer covering the non-bonding surface of the connection terminals for the LDU, increasing their strength and stability, and using integrated connection terminals to reduce the number of wiring lines, thereby stabilizing the connection terminal and pad distance during solder bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If connection terminals for LDU are supported in a cantilever shape protruding from the base layer, then the connection terminals are exposed and accessible for bonding, but the connection terminals are not rigid enough and may bend
Solution Approach 1:
The connection terminal structure combines multiple materials: a flexible portion made of flexible printed circuit board material for bendability, and a rigid portion made of rigid printed circuit board material for strength. This composite structure allows the terminal to be both accessible and rigid enough to prevent bending during bonding and operation.
Solution Approach 2:
The connection terminal is divided into two distinct segments: a flexible portion that provides accessibility and conformability, and a rigid portion that provides structural support and prevents bending. This segmentation allows each part to fulfill its specific function optimally.
2Ease of manufacture
If connection terminals are exposed on both sides of the flexure, then bonding is possible, but the distance between connection terminal and connection pad is unstable during solder bonding
Solution Approach 1:
The rigid portion of the connection terminal is designed with predetermined dimensions and positioning features that pre-establish the correct distance relationship with the connection pad before bonding occurs. This preliminary structural design ensures distance stability during the solder bonding process.
3Ease of manufacture
If connection terminals are used in current configuration, then existing manufacturing processes can be used, but cracks may occur in the solder and connection terminals due to shocks or heat cycles
Solution Approach 1:
The combination of flexible and rigid portions creates a structurally robust connection terminal that better withstands mechanical shocks and thermal cycling. The rigid portion provides resistance to deformation while the flexible portion accommodates thermal expansion differences, reducing stress concentration that would lead to cracks.
Data Source
AI summary
According to one embodiment, a head suspension assembly includes a support plate, a wiring member on the support plate, and a magnetic head mounted on the wiring member. The magnetic head includes a slider, a head element, connection pads, and a laser oscillation element on the slider. The wiring member includes a plurality of first connection terminals each having a bonding surface bonded to a connection pad of the slider and a second connection terminal including a bonding surface bonded to a connection pad of the laser oscillation element and a non-bonding surface opposite to the bonding surface. The wiring member includes a cover layer covering at least a part of the non-bonding surface of the second connection terminal.