Self-Locking Fastener for PCB Module Alignment Under Heatsink Load
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Solution Overview
Problem
During the installation of heatsinks in information handling systems, the heatsinks can tilt slightly when tightening the screws, causing an imbalance force on the CPU chipset, which can lead to thermal module unbalance and mis-alignment.
Innovation Solution
A self-locking fastening system is introduced, comprising a fastener with a hollow shaft, threaded portion, and protrusions with angled surfaces, and a nut with a projection and locking features. This system engages in two states: the first state allows rotation in response to a downward force, and the second state maintains the positioning of the fastener with respect to the nut, ensuring secure coupling of the computing module to the printed circuit board.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional screw fastening system is used to couple the heatsink to the PCB, then the installation process is simple, but the heatsink tilts during tightening causing imbalance force on the CPU chipset and thermal module unbalance
Solution Approach 1:
The fastening system is designed to automatically self-align and self-lock during the installation process. The angled surface of the protrusion engages with the angled surface of the locking feature, causing the fastener to automatically rotate into the correct position and lock without requiring manual alignment or complex alignment tools, thereby preventing thermal module unbalance while maintaining simple installation
Solution Approach 2:
The spring acts as an intermediary element between the fastener and the computing module, providing continuous contact force to maintain proper positioning. The spring compensates for any gaps or misalignments, ensuring the heatsink remains stable and balanced on the CPU chipset during and after installation
2Manufacturing precision
If a conventional screw fastening system is used, then the fastener can be easily installed, but it cannot prevent mis-alignment of the computing module with the printed circuit board
Solution Approach 1:
The fastening system incorporates preliminary alignment features including the angled surfaces on the protrusion and locking feature, and the sloped surfaces on the fastener that guide and pre-align the components before final engagement. This preliminary alignment mechanism prevents mis-alignment issues before they occur, while the spring provides continuous corrective force to maintain precision throughout the installation process
3Reliability
If the fastener is tightened to prevent tilting, then alignment improves, but the risk of damaging the CPU chipset or PCB increases
Solution Approach 1:
The spring provides beforehand cushioning by absorbing excess tightening force and providing continuous gentle contact pressure. This cushioning effect prevents the fastener from applying damaging forces to the CPU chipset or PCB while still maintaining sufficient attachment stability to prevent tilting and ensure proper alignment throughout operation
Data Source
AI summary
A fastening system, including: a fastener including: a hollow shaft; a threaded portion positioned on an outer surface of the hollow shaft; a first protrusion extending from an inner surface of the hollow shaft, the first protrusion including: a first angled surface; a first engagement surface; a nut corresponding to the fastener, including: a cavity having threaded portion; a projection positioned within the cavity of the nut, the projection including: a first locking feature positioned on an outer surface of the projection, the first locking feature including: a second angled surface; a first locking surface; wherein, in a first state of engagement of the fastener with the nut, the first angled surface of the first protrusion of the fastener engages with the second angled surface of the first locking feature of the projection to rotate the fastener with respect to the nut in response to downward force on the fastener.