Double-Sided PCB Power Block Cooling for Higher Device Density

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Solution Overview

Problem

Conventional cooling methods for semiconductor devices attached to printed circuit boards (PCBs) face challenges such as PCB deformation, bending, or fracture due to increased heat dissipation requirements, and high thermal resistance when heat is dissipated through the bottom surface, limiting the number of devices that can be integrated.

Innovation Solution

A cooling apparatus that utilizes a combination of thermal pads, thermal interface structures, and heat sinks on both top and bottom surfaces of the PCB, with spring-loaded fasteners and dielectric layers to efficiently dissipate heat while maintaining mechanical stability and allowing for increased semiconductor device integration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If heat sinks are attached to top surfaces of semiconductor devices mounted over a top surface of a PCB, then heat dissipation is improved, but the number of semiconductor devices that can be integrated is limited due to PCB deformation, bending, or fracture

Engineering Contradiction:
Improveheat dissipationVSAvoidnumber of semiconductor devices
Core Design Contradiction:
TemperatureVSQuantity of substance

Solution Approach 1:

The patent transitions from single-sided heat dissipation to double-sided heat dissipation by mounting semiconductor devices on both the top and bottom surfaces of the PCB. This dimensional change allows heat to be dissipated from both sides of the board, effectively doubling the heat dissipation capacity without increasing the thermal load on any single side, thereby preventing PCB deformation while integrating more devices.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent divides the heat dissipation function into two separate systems: one for the top surface with first semiconductor devices and first heat sinks, and another for the bottom surface with second semiconductor devices and second heat sinks. This segmentation allows independent thermal management on each side, preventing the cumulative thermal stress that causes PCB deformation when multiple devices are mounted on a single side.

Inventive Principle:
Principle #1Segmentation

2Quantity of substance

If the number of semiconductor devices mounted over the top surface of the PCB increases, then heat dissipation requirements increase, but the PCB may deform, bend, or fracture

Engineering Contradiction:
Improvenumber of semiconductor devicesVSAvoidPCB structural stability
Core Design Contradiction:
Quantity of substanceVSStability of the object's composition

Solution Approach 1:

By utilizing both top and bottom surfaces of the PCB for device mounting, the patent distributes the thermal and mechanical loads across two dimensions rather than concentrating them on one side. This dimensional distribution maintains PCB structural stability even as the total number of integrated devices increases.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent uses the bottom surface of the PCB as a counterbalancing dimension to offset the thermal and mechanical stress on the top surface. Devices and heat sinks on the bottom surface act as a thermal and structural counterweight, preventing the PCB from deforming under the cumulative load of multiple high-power devices.

Inventive Principle:
Principle #8Anti-weight (Counterweight)

3Quantity of substance

If heat dissipates through bottom surfaces of semiconductor devices, then device integration is improved, but thermal resistance is high

Engineering Contradiction:
Improvedevice integrationVSAvoidthermal resistance
Core Design Contradiction:
Quantity of substanceVSReliability

Solution Approach 1:

The patent segments the thermal path into two independent routes: one through the top surface heat sinks and another through the bottom surface heat sinks. Each path handles a portion of the total heat load, preventing any single path from experiencing excessive thermal resistance. This segmentation allows high device integration while maintaining acceptable thermal performance through distributed heat dissipation.

Inventive Principle:
Principle #1Segmentation

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 solution enables effective heat dissipation and increased power density on PCBs without causing deformation or bending, allowing for more semiconductor devices to be integrated while maintaining thermal efficiency and mechanical stability.

Implementation Method 1

a first thermal interface structure thermally coupled between the first thermal pad and the first heat sink, a second heat sink, and a second thermal interface structure thermally coupled between the second thermal pad and the second heat sink

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

heat sinks are attached to top surfaces of semiconductor devices mounted over a top surface of a PCB

Methodology Applied
Scientific EffectHeat sinking: Heat Sink

Data Source

PatentEP4310903A1Power block based on top-side cool surface-mount discrete devices with double-sided heat sinking
Publication Date: 2024.01.24 UNITED SILICON CARBIDE
  • EP4310903A1 patent drawingFigure 1A
  • EP4310903A1 patent drawingFigure 1B~1C
  • EP4310903A1 patent drawingFigure 2

AI summary

This disclosure relates to a cooling apparatus and a method for cooling semiconductor devices, wherein the cooling apparatus is disposed over a top surface and a bottom surface of a printed circuit board. The disclosed cooling apparatus comprises a printed circuit board, a first semiconductor device comprising a first thermal pad and mounted on a top surface of the printed circuit, a second semiconductor device comprising a second thermal pad and mounted on a bottom surface of the printed circuit, a first heat sink, a first thermal interface structure thermally coupled between the first thermal pad and the first heat sink, a second heat sink, and a second thermal interface structure thermally coupled between the second thermal pad and the second heat sink.