PCB Radiator Thermal Stress Mitigation via Intermediate Layer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing printed circuit boards (PCBs) with radiators face issues due to significant differences in heat expansion coefficients between the radiator and the substrate or resin layer, leading to potential disengagement and inadequate heat dissipation, particularly when coupled with LED devices.
Innovation Solution
A PCB design featuring a radiator with an electrically insulated core and conductive layers, a substrate with matching conductive layers, and a flexible member connecting two PCBs, allowing for improved heat dissipation through a heat dissipater coupled to the radiator and substrate, while minimizing thermal stress and expansion coefficient mismatches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a copper radiator is used to export heat from LED devices, then heat dissipation is improved, but heat expansion coefficient mismatch with the substrate causes radiator disengagement
Solution Approach 1:
An intermediate layer with thermal conductivity of 0.5-5 W/mK is introduced between the copper radiator and the substrate. This intermediary layer acts as a buffer that accommodates the thermal expansion coefficient mismatch between the copper radiator and the substrate, preventing disengagement while maintaining effective heat dissipation from the LED devices through the radiator assembly.
Solution Approach 2:
The radiator assembly is constructed as a composite structure comprising a copper radiator layer, an intermediate layer with specific thermal conductivity properties, and a substrate. This composite material approach allows optimization of each layer's properties: copper for high heat dissipation, intermediate layer for expansion mismatch accommodation, and substrate for structural support, achieving both thermal performance and structural reliability.
2Temperature
If a ceramic radiator is used to export heat, then heat dissipation is improved, but heat expansion coefficient mismatch with the resin layer causes radiator disengagement
Solution Approach 1:
An intermediate layer with thermal conductivity of 0.5-5 W/mK is positioned between the ceramic radiator and the resin layer substrate. This intermediary layer serves as a buffer that compensates for the thermal expansion coefficient difference between the ceramic radiator and the resin layer, preventing disengagement while preserving the ceramic radiator's superior heat dissipation capabilities.
Solution Approach 2:
The radiator assembly forms a composite structure with a ceramic radiator layer, an intermediate layer with controlled thermal conductivity, and a resin layer substrate. This composite construction allows each material to perform its optimal function: ceramic for heat dissipation, intermediate layer for thermal expansion accommodation, and resin layer for insulation and support, achieving both thermal performance and structural integrity.
3Reliability
If the PCB is made flexible to accommodate thermal expansion, then thermal stress is reduced, but manufacturing complexity increases
Solution Approach 1:
The PCB is designed with flexible regions that allow dynamic movement and deformation in response to thermal expansion forces. These flexible regions enable the PCB to accommodate dimensional changes during thermal cycling without generating excessive stress, while the rigid regions maintain structural integrity. This dynamic design approach manages thermal stress effectively while using standard flexible PCB manufacturing processes.
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 enhances heat dissipation and stability by aligning the thermal and electrical conductive layers, reducing the risk of radiator disengagement and improving the PCB's ability to manage heat generated by LED devices, thereby increasing the reliability and longevity of electronic components.
Implementation Method 1
a heat dissipater on the bottom surface coupled to the radiator and the substrate
Implementation Method 2
a first electrically conductive layer formed on a top and bottom surface of the electrically insulated core, a substrate having a second electrically conductive layer formed on a top and bottom surface of the substrate
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
A method of manufacturing a printed circuit board includes providing a substrate having at least one resin plate and a semi-cured sheet. A through hole is formed in the substrate to accommodate a radiator having an electrically conductive layer and an electrically insulated layer. The substrate and radiator are heat pressed to fully cure the epoxy and couple the substrate and radiator together. The excess resin is removed and electrically conductive layers are plated on the board. Surface circuits and a heat dissipating pattern are then etched into the conductive layer. An LED is attached to the printed circuit board. In some embodiments, a flexible segment is formed by removing a portion of the substrate. The radiator can have an electrically insulated layer extending at least partially across a surface of an electrically insulated and thermally conductive core.