Electric Device Substrate Fixing with Slits and Washers
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Solution Overview
Problem
Existing electric devices face stress issues due to differences in the linear coefficient of expansion between metal plates and substrates, which can lead to substrate damage from thermal expansion, as current methods do not adequately mitigate these stresses effectively.
Innovation Solution
The electric device design incorporates bosses at the substrate's corners and within a rectangle, with slits adjacent to these bosses to reduce rigidity and allow for inclination, along with the use of rubber washers at some fixation points to absorb deformation stress, while omitting washers at others to minimize substrate distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the substrate is rigidly fixed to the metal plate with multiple male screws, then the fixing strength is improved, but stress is generated in the substrate due to difference in linear coefficient of expansion
Solution Approach 1:
The patent applies different fixing methods at different locations: rubber washers are used at corner bosses (first bosses) to provide elastic stress mitigation, while rigid fixing without washers is used at the central boss (second boss) to prevent substrate distortion. This local differentiation resolves the contradiction by optimizing each location's fixing characteristics.
Solution Approach 2:
The fixing structure is segmented into multiple bosses (first bosses at corners, second boss at center) with different fixing characteristics. This segmentation allows the substrate to be fixed at multiple points with different compliance levels, reducing overall stress while maintaining positioning accuracy.
2Stress or pressure
If rubber washers are used at all fixation points, then stress mitigation is improved, but substrate distortion occurs due to excessive compliance
Solution Approach 1:
The patent applies rubber washers only at specific locations (corner bosses) where stress mitigation is most needed, while omitting them at the central boss to maintain positioning stability. This selective application resolves the contradiction between stress mitigation and positioning stability.
Solution Approach 2:
The fixing system is segmented into compliant regions (corner bosses with rubber washers) and rigid regions (central boss without washer). This segmentation allows the substrate to have both stress relief and stable positioning simultaneously at different locations.
3Stress or pressure
If the metal plate rigidity is reduced with slits, then stress mitigation is improved, but the structural strength of the metal plate deteriorates
Solution Approach 1:
The metal plate is segmented with slits that create localized flexibility zones near bosses without compromising the overall plate structure. The slits are positioned strategically to allow thermal expansion accommodation while maintaining global structural integrity.
Solution Approach 2:
The slits create local quality changes in the metal plate, providing flexibility only in specific regions where stress concentration occurs near bosses, while the rest of the plate maintains its full rigidity and strength for structural support.
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 design effectively reduces stress on the substrate by allowing the metal plate to deform and incline, thereby mitigating thermal expansion-induced stress, while allowing for a larger component installation area and improved vibration resistance.
Implementation Method 1
the rubber washers as electric bodies are deformed, so that stress generated in the substrate due to a difference in the linear coefficient of expansion between the metal plate and the substrate is mitigated
Implementation Method 2
stress generated around the second boss due to a difference in the linear coefficient of expansion between the substrate and the metal plate is mitigated when the metal plate is deformed so that the second boss is inclined
Data Source
AI summary
An electric device includes a substrate on which electronic components are mounted, and a metal plate to which the substrate is fixed. The metal plate includes first bosses provided at positions corresponding to four corners of the substrate, a second boss provided inside a rectangle that connects the four first bosses, and a slit that is provided adjacent to the second boss, and extends in non-parallel with any side of the rectangle. The substrate is fixed to each of the four first bosses with a first male screw, such that a rubber washer is sandwiched between the substrate and the first male screw. The substrate is fixed to the second boss with a second male screw, such that no rubber washer is sandwiched between the substrate and the second male screw.