Mounting Spring Design for Power Electronics Module Packages
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Solution Overview
Problem
Existing power electronics module packages face issues with non-uniform pressure distribution during mounting, leading to potential plastic deformation and strain due to over-tightening, as conventional screw-based mounting methods do not ensure even force application across the mounting area.
Innovation Solution
The use of mounting springs that absorb and distribute the force applied by screws, preventing over-tightening and ensuring even pressure across the package by translating the screw force onto a plateau portion of the lid, thereby maintaining the package's position on a heat sink without causing deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If screws are torqued to apply mounting force, then the package can be securely mounted to the heat sink, but the pressure may not be uniformly applied and over-tightening can cause plastic deformation
Solution Approach 1:
A compliant mounting plate is introduced as an intermediary component between the screws and the package substrate. This mounting plate distributes the localized screw torque across a broader area, transforming concentrated point loads into distributed pressure. The compliance of the mounting plate allows it to deform elastically, ensuring uniform pressure distribution while preventing stress concentration that would lead to plastic deformation of the package substrate.
Solution Approach 2:
The system changes the mechanical compliance parameter of the mounting structure by using a compliant mounting plate with controlled elastic properties. This parameter change allows the mounting plate to deform under screw torque, converting rigid force application into flexible, distributed pressure. The compliance parameter is tuned to provide sufficient mounting force while maintaining pressure uniformity across the thermal interface.
2Temperature
If screws are torqued to ensure optimal thermal interface pressure (80-125 psi), then thermal performance is improved, but over-tightening can easily occur causing damage
Solution Approach 1:
The compliant mounting plate serves as a cushioning element that is pre-installed between the screws and the package substrate. This cushioning layer absorbs excess force from over-tightening before it can reach the package substrate. The elastic properties of the mounting plate allow it to compress and deflect, providing a safety margin that prevents damage even when screw torque exceeds the optimal range for thermal interface pressure.
Solution Approach 2:
The mounting plate acts as a protective intermediary that decouples the screw torque application from the package substrate. By placing this compliant layer in between, the system gains a buffer zone that regulates force transmission. The mounting plate ensures that the package substrate never experiences forces beyond its elastic limit, thereby preventing plastic deformation while still achieving the required 80-125 psi thermal interface pressure.
3Temperature
If mounting pressure is increased to ensure optimal thermal contact, then thermal interface efficiency improves, but non-uniform pressure distribution causes deformation
Solution Approach 1:
The compliant mounting plate is positioned as an intermediary layer between the screw mounting mechanism and the package substrate. This intermediary component distributes the mounting pressure uniformly across the entire thermal interface area, preventing stress concentration at specific points. The plate's compliance allows it to conform to surface variations, ensuring consistent pressure distribution that maintains both thermal contact efficiency and structural integrity of the package substrate.
Solution Approach 2:
The system modifies the mechanical parameter of the mounting structure by introducing a compliant layer with specific elastic modulus and thickness. This parameter change transforms the pressure distribution profile from non-uniform (with high stress concentrations) to uniform across the thermal interface. The compliant mounting plate's material parameters are selected to provide optimal balance between achieving sufficient thermal contact pressure and preventing structural deformation of the package.
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 provides improved mounting pressure and prevents plastic deformation, ensuring even force distribution and maintaining the package's position on a heat sink, reducing the risk of damage from over-tightening and enhancing thermal interface efficiency.
Implementation Method 1
mounting springs that absorb and distribute the force applied by screws
Implementation Method 2
translating the screw force onto a plateau portion of the lid, thereby maintaining the package's position on a heat sink
Data Source
AI summary
A module package can include a substrate; at least one device component configured to be positioned on the substrate; a module package lid configured to be positioned over the at least one device component and on the substrate, the module package lid exhibiting a plateau portion; and at least one mounting spring configured to be positioned on the module package lid, wherein the at least one mounting spring is configured to be mechanically coupled with a mounting surface and further positionally secure the module package lid and the at least one device component. Each mounting spring can include a middle portion; an end portion having a mounting hole; and a curved section between the middle portion and the end portion, the middle portion arranged to mate with the plateau portion of the module package lid when the end portion are secured to the substrate, the curved section being configured to prevent contact with a first corner portion of the module package lid.