Thermally Isolating Mounting Boss for PCB Chassis Grounding
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Solution Overview
Problem
Conductive heat transfer from printed circuit boards (PCBs) to chassis in information handling systems is not effectively managed by existing mounting bosses, leading to high surface temperatures and potential electrical grounding issues when using thermal insulators.
Innovation Solution
Thermally isolating mounting bosses with a base section and a plurality of pillars, where the combined cross-section area of the pillars is less than the base section, providing structural support and maintaining electrical grounding while increasing thermal resistance to reduce heat conduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If metal mounting bosses are used to provide strong support and grounding, then structural strength and electrical grounding are improved, but heat conduction from PCB to chassis increases
Solution Approach 1:
The mounting boss is divided into a base section and multiple isolated pillar sections. The base section maintains full contact with the chassis for grounding, while the pillar sections contact the PCB at discrete points. This segmentation creates thermal isolation paths while preserving electrical grounding through the base section.
Solution Approach 2:
Different sections of the mounting boss have different thermal properties. The base section is thermally conductive for grounding, while the pillar sections are thermally isolated from the base section, creating localized thermal resistance at the PCB mounting interface.
2Temperature
If thermal insulators are added between PCB and mounting boss, then heat conduction is reduced, but electrical grounding capability deteriorates
Solution Approach 1:
The mounting structure is segmented into thermally isolated pillar sections that contact the PCB and a separate base section that contacts the chassis. This segmentation allows thermal insulation between the PCB and mounting boss while maintaining electrical grounding through the conductive base section.
Solution Approach 2:
The base section acts as an intermediary element that provides both electrical grounding and thermal management. It decouples the thermal path from the electrical grounding path, allowing heat to be blocked while maintaining electrical contact.
3Temperature
If the cross-section area of mounting boss is reduced to decrease heat conduction, then thermal resistance is improved, but structural support strength deteriorates
Solution Approach 1:
The mounting boss cross-section is segmented into multiple smaller pillar cross-sections distributed across the base section. The combined area of these pillars provides sufficient structural support while each individual pillar creates thermal isolation paths, reducing overall heat conduction.
Solution Approach 2:
The pillar sections have smaller cross-sectional areas than a solid mounting boss would have, creating localized thermal resistance. However, the distributed arrangement of multiple pillars maintains sufficient structural support through collective load-bearing capacity.
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 reduces heat conduction from PCBs to the chassis, maintaining lower surface temperatures and ensuring electrical grounding, with simulated temperature profiles showing a significant reduction in chassis surface temperature.
Implementation Method 1
a thermal insulator for positioning between the base section and a first side of the PCB
Implementation Method 2
Metal mounting bosses provide strong support and a grounding circuit for the PCB
Data Source
AI summary
A thermally isolating mounting boss for mechanically and electrically coupling a PCB to a chassis while thermally isolating the PCB from the chassis comprises a base section with a base surface coupled to the chassis and an isolation section comprising a plurality of pillars for thermally isolating the PCB from the chassis. A connector maintains the PCB in contact with the plurality of pillars, wherein the connector and the plurality of pillars form grounding circuits. The small cross-section area of each pillar and the cross-section area of the connector have increased thermal resistance to thermally isolate the PCB from the chassis. The pillars may extend from the base section or may be arranged radially outward of the base section.