MOSFET Half-Bridge Module with Elastic Clip Mounting
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Solution Overview
Problem
Existing power converters face challenges in efficiently dissipating heat and reducing parasitic inductance, leading to voltage ringing and electromagnetic interference, particularly in high-power density applications like electric vehicle chargers, where traditional heat sink attachment methods are inefficient and complex.
Innovation Solution
A power switching device using a multiple-layer PCB board with a flat back side directly attached to a heat sink via elastic retaining clips, minimizing parasitic inductance and enhancing thermal contact by eliminating the need for screws and optimizing the placement of ceramic capacitors and thermal vias for effective heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional screw mounting methods are used to attach heat sinks, then secure mechanical connection is achieved, but assembly complexity and thermal contact resistance increase
Solution Approach 1:
The patent extracts the mounting function from traditional screw holes and relocates it to the PCB edges, using simple retaining clips that attach to edge-mounted holes. This separates the thermal contact function (maintained by spring pressure) from the mechanical attachment function (performed by edge clips), eliminating the need for through-hole screws and reducing assembly complexity.
Solution Approach 2:
The patent introduces spring-loaded retaining clips as intermediary components that provide both mechanical attachment and thermal pressure. These clips act as mediators between the heat sink and PCB, combining the functions of mechanical fastening and thermal contact maintenance without requiring complex screw assemblies.
2Temperature
If multiple mounting holes are used to improve thermal contact, then thermal resistance is reduced, but the board area available for other components decreases
Solution Approach 1:
The patent segments the mounting function into two parts: mechanical attachment at the edges (retaining clips) and thermal contact at the center (spring pressure on thermal pad). This segmentation allows the thermal pad to be a small localized feature rather than requiring multiple large mounting holes distributed across the board, preserving board area for other components.
Solution Approach 2:
The patent moves the mechanical attachment points from the board surface (2D plane) to the board edges (1D perimeter), freeing up board surface area. The thermal contact is maintained through vertical spring pressure applied at the center, separating the spatial requirements of mechanical attachment and thermal contact.
3Strength
If through-hole mounting is used for power switches, then mechanical strength is improved, but parasitic inductance increases significantly
Solution Approach 1:
The patent replaces the mechanical through-hole mounting system with a surface-mount device (SMD) system. Power switches are mounted on the board surface using SMD techniques, eliminating the long vertical leads of through-hole components that create high parasitic inductance. The mechanical strength is maintained through the rigid PCB structure and edge-retaining clips rather than through-hole fastening.
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 significantly improves thermal contact and reduces parasitic inductance, leading to more efficient heat dissipation and reduced electromagnetic interference, enabling compact, high-power density designs with lower assembly complexity and cost.
Implementation Method 1
fostering thermal contact between the flat portion of the back side of the PCB power board and the flat thermal pad of the heat sink
Implementation Method 2
heat sinks are widely used to dissipate thermal energy generated by PCB power boards
Data Source
Figure 1
Figure 2a~2c
Figure 2d
AI summary
A power switching device comprising at least one heat sink (50) and at least one multiple layer PCB power board (10) comprising at least one two-switch leg structure comprising power switching components (14) and associated driving circuits, having a said power board having a front side comprising said power switching components (14), and a back side comprising at least a flat portion containing no surface-mouted components, characterised in that said board is configured such that the current flows from a top layer to a bottom layer, to minimize power-loop inductance. Said PCB power board (10) has a bottom side provided with a flat portion for connection to a flat thermal pad (32) which is part of said heat sink (50), and is connected to said heat sink (50) by means of at least one elastic retaining clip (30), wherein said at least one elastic retaining clip (30) exerts mechanical pressure onto at least one of said power switching components (14), said mechanical pressure being directed towards said flat thermal pad (32).