Leaf Spring Heat Sink Coupling With Reduced PCB Keep-Out Area
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Solution Overview
Problem
Conventional leaf spring designs for heat sinks on printed circuit boards (PCBs) require large 'keep-out' areas, limiting PCB design and performance due to the need for a substantial footprint opposite heat-generating integrated circuits (ICs), which restricts the placement of other electronic components and reduces transmission efficiency.
Innovation Solution
A leaf spring design with a central aperture and two spring arms, each with a through-hole for fasteners, featuring perpendicular bending axes that allow for a smaller keep-out area on the PCB, enabling greater force application with fewer screws, thus accommodating ICs and other components closer to the heat sink.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If conventional leaf spring designs are used to couple heat sinks to integrated circuits, then sufficient pressing force can be applied, but large keep-out areas are required on the back side of the PCB
Solution Approach 1:
The leaf spring is segmented into multiple spring arms (first spring arm, second spring arm, etc.) that can be distributed across different locations on the PCB. This segmentation allows the pressing force to be applied through distributed spring arms rather than requiring a single large spring structure, thereby reducing the keep-out area while maintaining sufficient pressing force on the heat sink.
Solution Approach 2:
The invention transitions from a planar leaf spring design to a three-dimensional structure with spring arms that extend in multiple directions and can be positioned at different heights. The spring arms can be configured with different lengths and orientations, allowing force application from multiple spatial dimensions. This dimensional change enables more efficient space utilization on the PCB and reduces the required keep-out area.
2Reliability
If large keep-out areas are allocated on the back side of the PCB, then heat sink coupling is achieved, but transmission latency increases due to component placement constraints
Solution Approach 1:
By segmenting the leaf spring into multiple spring arms that can be distributed across the PCB, the design allows electronic components to be placed in the areas previously occupied by the keep-out zone. This enables shorter transmission paths between components and the heat sink, reducing transmission latency while maintaining reliable heat sink coupling through the distributed spring arm structure.
3Device complexity
If fewer fasteners are used to reduce device complexity, then manufacturing is simplified, but achieving sufficient pressing force becomes more difficult
Solution Approach 1:
The spring arms are designed to be elastic and deformable, allowing them to dynamically adjust and distribute the pressing force across multiple contact points on the heat sink. This dynamic capability enables fewer fasteners to achieve sufficient total pressing force, as each spring arm can independently contribute to the overall force while accommodating variations in heat sink positioning and PCB deformation.
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 allows for more efficient heat sink coupling with reduced PCB space requirements, enabling better component placement and improved performance by allowing ICs to be positioned closer to the heat sink while maintaining effective force application.
Implementation Method 1
spring-based devices can be used to fix a heat sink against one or more heat-generating chips within a computing device with relatively high, uniform pressure
Data Source
AI summary
Various embodiments of the present disclosure relate to a leaf spring for coupling a heat sink to an integrated circuit, where the leaf spring includes a central portion that has an aperture, a first spring arm that is formed on a first side of the central portion and includes a first through-hole for a first fastener, and a second spring arm that is formed on a second side of the central portion and includes a second through-hole for a second fastener. In various embodiments, a first bending axis passes through the first side and is substantially perpendicular to a longitudinal axis of the leaf spring that passes through the first through-hole and the second through-hole, and a second bending axis passes through the second side and is substantially perpendicular to the longitudinal axis of the leaf spring.