Over-Torque Mounts for PCB Heatsink Thermal Coupling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Electronic devices with aluminum PCBs face damage from flexure due to improper fastening, especially when using heat sinks, as excessive torque can cause the PCB to flex, potentially damaging surface-mounted components like ceramic capacitors.
Innovation Solution
The implementation of an over-torque protection feature in the package's mounts, which includes structurally weakest links that fail at a predetermined torque level, providing a mechanical indication of excessive force and preventing damage to the PCB by allowing the mounts to deform or break before the PCB flexes excessively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If machine screws exert enough force to assure contact and thermal coupling between the heat sink and aluminum PCB, then thermal coupling is improved, but the aluminum PCB may flex and damage surface-mounted components due to over-tightening
Solution Approach 1:
The patent applies preliminary action by incorporating over-torque protection features (such as torque-limiting mechanisms or compliant mounting structures) into the mounting hardware before assembly. These features are pre-designed to fail or deform at a predetermined torque level, preventing excessive force from being applied to the PCB during the fastening process. This ensures that thermal coupling is achieved without risking component damage from over-tightening.
Solution Approach 2:
The patent implements beforehand cushioning by using compliant or flexible mounting elements between the heat sink and PCB assembly. These cushioning elements absorb excess mechanical stress and torque, allowing the mounting structure to accommodate variations in surface flatness and thermal interface material thickness without transmitting damaging forces to the PCB and its sensitive components.
2Temperature
If the aluminum base layer or mounting surface is non-planar, then thermal contact may be insufficient, but over-tightening fasteners to compensate causes the aluminum base layer to flex
Solution Approach 1:
The patent applies dynamics by using flexible or compliant mounting structures that can adapt to non-planar surfaces. Instead of relying on rigid fasteners that transmit excessive force, the mounting structure incorporates elements that can deform or flex to accommodate surface irregularities, maintaining thermal contact without causing PCB flexure. This dynamic adaptation allows the system to handle variations in surface flatness while protecting the PCB.
Solution Approach 2:
The patent implements parameter changes by modifying the mechanical properties of the mounting structure to be more compliant. This includes using materials with different stiffness characteristics, adjusting fastener torque specifications, or incorporating elastic elements that change their mechanical behavior under load. These parameter changes allow the mounting system to achieve adequate thermal contact on non-planar surfaces without exceeding the PCB's flexure tolerance.
3Temperature
If thermal interface material (paste, gel, or pad) is placed between surfaces to fill air gaps, then thermal transfer is improved, but the material may cause the aluminum base layer to flex if fasteners are over-tightened
Solution Approach 1:
The patent applies preliminary action by pre-configuring the mounting structure with torque-limiting features or compliant elements that account for the presence of thermal interface material. These features are designed beforehand to prevent over-tightening, recognizing that the compressible nature of thermal pads, gels, or pastes can lead to excessive force application if not properly accounted for in the mounting design.
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 effectively prevents damage to flex-sensitive components by providing a mechanical fuse that fails before causing excessive flexure, ensuring secure attachment to heat dissipation objects without increasing the PCB's thickness or weight, and is suitable for use with thermal pads and materials that may enhance flexure risk.
Implementation Method 1
the PCB may be bolted or clamped to a heat sink with a thermally conductive paste, gel, or pad placed therebetween to fill potential air gaps between contact surfaces, and provide a thermal transfer path
Implementation Method 2
an over-torque protection feature connected between the opening and the sidewall... each mount comprising an opening via which the mount is fastenable to the heat dissipation object and an over-torque protection feature connected between the opening and the sidewall
Data Source
AI summary
A package for securing a PCB to a heatsink includes mounts with over-torque protection features. The PCB is seated in an open end of the package. Each mount includes a threaded opening for securing the package to the heatsink such that the base layer of the PCB is thermally coupled to the heat sink. The over-torque protection features are connected between the threaded opening and a sidewall of the package. The over-torque protection features may be designed to structurally fail and/or deform in response to over-torqueing of the fasteners, thereby inhibiting flexure of the PCB.