PCB Assembly Thermal Dissipation via Through-Hole Pins
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Solution Overview
Problem
High power integrated circuit chips on printed circuit boards face thermal dissipation challenges due to the difficulty in arranging a short path length between heat generators and heat sinks, leading to excessive temperatures that can damage the circuits, especially in densely layered PCBs with conventional thermal transfer methods.
Innovation Solution
A printed circuit board assembly with a ball grid array (BGA) on its underside, featuring through-holes in a second PCB for thermally conductive pins and matching studs that enhance heat transfer to a heat sink, allowing for efficient thermal dissipation and easy replacement of integrated circuit chips without disturbing other components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional thermal transfer methods are used through PCB layers, then the structure is simple, but the thermal dissipation rate is insufficient leading to excessive temperatures
Solution Approach 1:
The patent introduces a vertical through-hole dimension through the PCB layers, creating a direct thermal pathway from the BGA heat source through the PCB to the heat sink. This three-dimensional thermal conduction path dramatically reduces thermal resistance compared to conventional lateral heat transfer through multiple PCB layers, enabling effective heat dissipation from high-power chips.
Solution Approach 2:
The patent employs thermally conductive pins as intermediary elements that bridge the BGA and heat sink. These pins serve as dedicated thermal conduits, transferring heat efficiently from the integrated circuit through the PCB structure to the heat sink, thereby resolving the thermal management challenge without requiring direct contact between the chip and heat sink.
2Temperature
If a short path length between heat generators and heat sinks is arranged, then thermal dissipation improves, but the PCB layout becomes more difficult especially with multiple layers
Solution Approach 1:
The patent segments the thermal management function into distinct components: the BGA with integrated heat source, the through-hole thermal pathway, the thermally conductive pins, and the heat sink. This segmentation allows each component to be optimized independently while maintaining a simple overall assembly process, resolving the conflict between thermal efficiency and manufacturing ease.
Solution Approach 2:
By transitioning from lateral heat transfer within PCB layers to vertical heat transfer through the PCB thickness, the patent achieves a shorter thermal path length. The through-hole configuration provides a direct upward/downward thermal conduit that bypasses the complex lateral routing required in conventional multi-layer PCB designs, thereby improving thermal dissipation without significantly complicating the PCB layout.
3Reliability
If integrated circuit chips are sealed in boxes, then protection is provided, but replacement of chips requires replacing the entire sealed box
Solution Approach 1:
The patent separates the protective enclosure function from the integrated circuit chip itself. The BGA package provides chip protection while the through-hole and pin assembly serves as a standardized mounting interface. This segmentation enables the chip to be replaced independently by removing the BGA from the through-hole assembly, eliminating the need to replace the entire sealed box and thereby improving repairability while maintaining protection.
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 provides a more effective thermal interface and path for heat dissipation from the BGA to the heat sink, ensuring satisfactory thermal management and facilitating the replacement of integrated circuit chips without damaging the assembly, thus preventing overheating and extending the lifespan of high-power components.
Implementation Method 1
a thermally-conductive pin projecting normally into the through-hole or a respective one of the through-holes in the second PCB, and, for each pin, a thermally-conductive stud of the same cross-section as the pin, bonded to the BGA and disposed within the through-hole between the pin and the first PCB in thermal contact with the pin
Data Source
AI summary
An assembly comprising a first printed circuit board, PCB, with a ball grid array, BGA, on its underside, a second PCB facing the first PCB and having at least one through-hole between its top and bottom surfaces, its top surface printed with a circuit pattern bonded to the BGA, a heat sink layer facing the bottom surface of the second PCB and having at least one thermally-conductive pin projecting normally into the through-hole or a respective one of the through-holes in the second PCB, and, for each pin, a thermally-conductive stud of the same cross-section as the pin, bonded to the BGA and disposed within the through-hole between the pin and the first PCB in thermal contact with the pin.