Head Gimbal Assembly Laser Diode Solder Connection Stability
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Solution Overview
Problem
Conventional head gimbal assemblies using solder connections for thermally assisted magnetic heads experience mechanical stress due to surface tension, leading to unstable connection conditions and reduced stability, especially with the inclusion of laser diodes which increase the complexity of solder connections.
Innovation Solution
A method of manufacturing a head gimbal assembly where a single solder ball is used to connect the laser diode to the flexure, with a preliminary heat step to raise the solder ball's temperature before melting, forming a solder connector with a curved surface to distribute stress evenly and improve connection stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple solder connections are used to connect the laser diode to the flexure, then the electrical connection is ensured, but the mechanical stress and connection instability increase due to surface tension
Solution Approach 1:
The patent merges multiple solder connections into a single solder ball connection. The single solder ball simultaneously connects the laser diode electrode to the flexure wiring, eliminating the need for multiple separate solder joints. This reduces the complexity of solder connections while maintaining electrical connectivity, and crucially reduces the cumulative mechanical stress from multiple solder joints to a single stress point that can be more effectively managed through the curved surface design.
Solution Approach 2:
The patent segments the solder connection into a two-stage process: first placing the solder ball in an unmelted state to establish mechanical contact, then selectively melting only the portion needed for electrical connection. This segmentation allows the connection to be formed with minimal solder material, reducing surface tension effects while ensuring adequate electrical conductivity.
2Reliability
If a large amount of solder is used to ensure reliable connection, then the electrical connection is improved, but the mechanical stress from surface tension increases causing connection instability
Solution Approach 1:
The patent applies partial action by melting only the necessary portion of the solder ball to achieve electrical connection, rather than melting the entire solder ball. The unmelted portion remains as a solid mechanical anchor, providing structural support while the melted portion creates the electrical pathway. This minimizes the amount of solder subjected to surface tension forces while ensuring adequate electrical conductivity.
Solution Approach 2:
The patent utilizes the spherical shape of the solder ball and creates a curved solder connector surface. The curved surface distributes mechanical stress more evenly across the connection interface, reducing stress concentration points. The spherical geometry naturally provides a compact, stress-resistant structure that maintains connection integrity under thermal and mechanical loads.
3Ease of manufacture
If conventional soldering is used without preliminary heating, then the process is simple, but the solder ball creates excessive mechanical stress due to sudden melting and surface tension
Solution Approach 1:
The patent applies preliminary heating to the solder ball before the main melting step. This pre-heating reduces the temperature differential during melting, causing the solder to melt more gradually and uniformly. This preliminary action reduces the sudden expansion and surface tension effects that occur with rapid melting, thereby reducing mechanical stress on the connection while adding only a minor step to the manufacturing process.
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 reduces mechanical stress and enhances the stability of the connection conditions by gradually melting the solder ball, minimizing surface tension effects and preventing issues like peel-off or lift-up, thereby improving the reliability and stability of the head gimbal assembly.
Implementation Method 1
a solder ball arrangement step of arranging only one solder ball so that the laser diode is connected to the flexure; a connecting ball attaching step of attaching the connecting ball to the electrode surface and the flexure
Implementation Method 2
the solder ball arrangement step is performed using a connecting ball, as the solder ball, having a size larger than a wiring gap between an electrode surface of the laser diode and a wiring end part, of the flexure, which is closest to the electrode surface and being in unmelted-solid condition
Implementation Method 3
near-field light is used as means for heating the magnetic recording medium in the conventional thermally assisted magnetic head
Implementation Method 4
records data while instantaneously heating and thereby increasing the temperature of a portion of the magnetic recording medium where data will be recorded
Data Source
AI summary
A method of manufacturing a head gimbal assembly includes a head connecting step which a thermally assisted magnetic head is connected to a suspension. The head connecting step includes a solder ball arrangement step which only one solder ball is arranged so that a laser diode of the thermally assisted magnetic head is connected with a flexure of the suspension, in an assembly structure which a slider of the thermally assisted magnetic head is adhered to the suspension. The solder ball arrangement step is performed using a connecting ball, as the solder ball, having a size larger than a wiring gap and being in unmelted-solid condition. The head connecting step includes a heat step which an electrode surface of the laser diode is heated.