Conduction Cooled Circuit Board Assembly Heat Pipe Rail
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Solution Overview
Problem
High thermal resistance in heat transfer paths within avionics and other electronic systems leads to increased temperature gradients between electronic devices and heat sinks, affecting device performance, as previous assemblies fail to adequately dissipate the heat generated by high-power printed circuit boards.
Innovation Solution
A conduction-cooled circuit board assembly incorporating a thermally conductive frame, attached circuit boards, and heat pipes that transfer heat from the boards to a rail and then to the chassis, utilizing good conductive paths to dissipate heat effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If heat is transferred through the PCB and chassis wall to the heat sink, then heat dissipation occurs, but high thermal resistance causes temperature to increase leading to larger temperature gradients that adversely affect device performance
Solution Approach 1:
The invention divides the heat transfer path into multiple segments by introducing intermediate heat dissipation components (heat sinks, heat pipes, thermal vias) between the heat-generating PCB areas and the chassis wall. This segmentation creates multiple parallel heat transfer pathways, reducing the thermal resistance of any single path and thereby reducing temperature gradients across the PCB.
Solution Approach 2:
The invention introduces intermediary heat dissipation components (such as heat sinks attached to the PCB, heat pipes connecting PCB areas to the chassis, and thermal via structures) that act as mediators in the heat transfer path. These intermediaries provide low thermal resistance pathways for heat flow, reducing the overall thermal resistance and temperature gradients without requiring changes to the fundamental PCB-chassis mounting structure.
2Power
If PCB performance and power are increased, then computational capability improves, but temperature generated by the PCBs increases significantly
Solution Approach 1:
The invention applies local quality by placing heat dissipation components specifically at high heat-generating areas of the PCB rather than uniformly across the entire board. Heat sinks are positioned over high-power device locations, heat pipes are connected to hot spots, and thermal vias are concentrated in areas with high power density. This localized approach efficiently manages heat from high-power PCBs without adding unnecessary components throughout the entire assembly.
Solution Approach 2:
The invention utilizes another dimension by extending heat dissipation structures in the vertical direction (z-axis) rather than only in the plane of the PCB. Heat sinks protrude from the PCB surface, heat pipes extend vertically to connect to the chassis, and thermal vias create three-dimensional heat transfer pathways through the PCB layers. This dimensional extension provides additional surface area for heat dissipation and creates multiple heat transfer pathways that reduce PCB temperature.
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 lowers the operating temperature of circuit board assemblies by enhancing heat dissipation through improved conductive paths, addressing the inefficiencies of previous assemblies in managing increased heat from high-power PCBs.
Implementation Method 1
Heat pipes employ evaporative cooling to transfer thermal energy from one point to another by the evaporation and condensation of the fluid
Implementation Method 2
the fluid inside the pipe at that end evaporates and increases the vapor pressure inside the cavity of the heat pipe
Implementation Method 3
The latent heat of evaporation absorbed by the vaporization of the fluid removes heat from the hot end of the pipe
Implementation Method 4
Heat pipes have been used to assist in the transfer of heat from the PCBs
Implementation Method 5
The vapor pressure at the hot end of the pipe is higher than the equilibrium vapor pressure at the cooler end of the pipe, and this pressure difference drives a rapid mass transfer to the condensing end where the vapor condenses, releases its latent heat, and transfers heat to the cool end of the pipe
Implementation Method 6
heat is conducted from the area to the chassis through the frame and the first surface
Data Source
AI summary
A conduction cooled circuit board assembly may include a frame and at least one circuit board attached to the frame, having at least one area to be cooled. The assembly may also include at least one rail attached to the frame, and at least one heat pipe having a first end and a second end, the first end disposed near the area and the second end in contact with the rail so as to transfer heat from the area to the rail.