Electronic Device Back Plate Isolating Cooling Stress From Solder Joints

Solution Overview

Problem

Existing electronic devices face a trade-off between reducing thermal resistance and maintaining connection reliability, as the application of a back plate to compress a heat conductive member often leads to distortion in the printed circuit board, degrading the connection reliability of electronic components.

Innovation Solution

The design includes a back plate with a main body portion overlapping and contacting the printed circuit board to compress the heat conductive member, while leg portions spaced apart from the board are fixed through holes without contacting it, allowing for reduced thermal resistance without stress on solder joints.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a back plate is applied to compress the heat conductive member, then thermal resistance is reduced, but the printed circuit board distorts and connection reliability degrades

Engineering Contradiction:

Improveconnection reliabilityVSAvoidthermal resistance

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The back plate is segmented into a main body portion and multiple leg portions. The main body portion contacts the printed circuit board to compress the heat conductive member, while the leg portions extend outward and are spaced apart from the board, allowing stress isolation during fixing.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The leg portions act as intermediaries between the fixing parts and the main body portion. By spacing the leg portions away from the printed circuit board, they mediate the fixing process to prevent stress transmission to the board and electronic components.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the back plate contacts the printed circuit board to compress the heat conductive member, then thermal resistance is reduced, but stress is applied to solder joints during fixing

Engineering Contradiction:

Improvesolder joint reliabilityVSAvoidthermal resistance

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The back plate is segmented into a main body portion and multiple leg portions. The main body portion contacts the printed circuit board to compress the heat conductive member, while the leg portions extend outward and are spaced apart from the board, allowing stress isolation during fixing.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The fixing function is extracted from the main body portion and assigned to the leg portions. By spacing the leg portions away from the printed circuit board, the harmful stress application is eliminated while retaining the beneficial compression function.

Inventive Principle:

Principle #2Taking out (Extraction)

3Stability of the object's composition

If fixing parts pass through the printed circuit board to secure the cooler, then the cooler is firmly fixed, but distortion occurs around the fixing portion

Engineering Contradiction:

Improvecooler fixation stabilityVSAvoidconnection reliability

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The back plate is segmented into a main body portion and multiple leg portions. The main body portion contacts the printed circuit board to compress the heat conductive member, while the leg portions extend outward and are spaced apart from the board, allowing stress isolation during fixing.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The leg portions act as intermediaries between the fixing parts and the main body portion. By spacing the leg portions away from the printed circuit board, they mediate the fixing process to prevent stress transmission to the board and electronic components.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 configuration effectively reduces thermal resistance while suppressing the degradation of connection reliability by isolating the stress from the fixing process, ensuring stable component mounting.

Implementation Method 1

a heat conductive member interposed between the electronic component and the cooler

Methodology Applied

Scientific EffectHeat conduction: Conduction (thermal)

Implementation Method 2

The main body portion of the back plate is disposed to overlap with at least a part of the electronic component in a plan view and compress the heat conductive member

Methodology Applied

Scientific EffectCompression: Compression

Data Source

PatentUS20250254786A1Electronic device

Publication Date: 2025.08.07 DENSO CORP

AI summary

An electronic device includes a printed circuit board, an electronic component disposed on a first surface of the printed circuit board, a cooler facing the first surface, a heat conductive member interposed between the electronic component and the cooler, and a back plate disposed on a second surface of the printed circuit board. A main body portion of the back plate is disposed to overlap with at least a part of the electronic component in a plan view and in contact with the second surface. Leg portions of the back plate extend from the main body portion, and are spaced apart from the second surface of the printed circuit board. A fixing part for fixing at least one of the leg portions of the back plate and the cooler passes through a through hole of the printed circuit board, and is not in contact with the printed circuit board.