Housing-side separating layer for stress decoupling in potted electronics
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing devices face mechanical stress issues due to potting compound shrinkage, leading to tensile stress on electrical contact points, which can cause cracks and failure of the electrical circuit, exacerbated by thermal expansion and shear forces.
Innovation Solution
A stress-relief gap is introduced between the housing and the substrate, allowing the potting compound to detach from a specially designed wall within the housing, preventing lateral movements and reducing mechanical stress on the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the potting compound adheres to the housing inner walls during hardening, then mechanical fixation is achieved, but tensile stress is generated on the substrate and electronic components due to shrinkage
Solution Approach 1:
The housing inner wall is segmented into two functional zones: an adhesion-promoting zone and a detachment-promoting zone. This segmentation allows the potting compound to adhere in some areas while detaching in others, creating a stress-relief gap that prevents tensile stress transmission to the substrate.
Solution Approach 2:
Different surface properties are applied to different regions of the housing inner wall. The adhesion-promoting zone has high surface energy and roughness to maximize bonding, while the detachment-promoting zone has low surface energy and smoothness to minimize bonding. This local quality differentiation enables selective adhesion/detachment behavior.
2Stress or pressure
If a relaxation gap is formed between the substrate and potting compound, then tensile stress is reduced, but lateral movements occur causing shear forces on electronic components
Solution Approach 1:
The stress management function is segmented between two locations: the relaxation gap on the substrate side reduces tensile stress, while the detachment zone on the housing side prevents lateral movement. This segmentation of stress relief mechanisms addresses both types of mechanical stress.
Solution Approach 2:
The detachment-promoting zone acts as an intermediary mechanism that allows controlled detachment of the potting compound from the housing wall. This intermediary zone enables the system to accommodate substrate movement while preventing harmful lateral forces from being transmitted to the electronic components.
3Stress or pressure
If the housing wall is made elastic with spring mechanism, then shrinkage stress is compensated, but device complexity increases
Solution Approach 1:
Instead of changing the mechanical structure of the housing to an elastic spring mechanism, the invention changes the surface energy parameters of the housing inner wall. By controlling wettability and surface roughness, the housing maintains its simple structure while achieving stress compensation through controlled adhesion/detachment behavior.
Solution Approach 2:
The mechanical spring mechanism is replaced with a surface chemistry-based solution. The housing wall uses surface treatments (plasma, chemical, or physical modifications) to create zones with different adhesion properties, substituting a complex mechanical system with a simpler surface property-based system.
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 reduces mechanical stress on electrical contact points, preventing cracks and enhancing the reliability of the electrical circuit by minimizing contamination-induced damage through controlled adhesion and detachment of the potting compound.
Implementation Method 1
The potting compound can adhere to the housing and detach from the wall
Implementation Method 2
When the casting compound hardens, which could happen when a plastic is used as the casting compound by polymerizing, the casting compound shrinks significantly
Implementation Method 3
When the casting compound hardens, which could happen when a plastic is used as the casting compound by polymerizing
Implementation Method 4
EP 0 398 108 A1 therefore proposes a special design for the plastic housing, with a housing wall of the plastic housing being folded into a spring mechanism
Data Source
Figure 1
AI summary
The invention relates to a device (2), which comprises a substrate (12) for carrying an electrical circuit (14), a housing (4) for enclosing the substrate (12), and a potting compound (22) accommodated in the housing (4), which potting compound at least partially encloses the substrate (12). The potting compound (22) can adhere to the housing (4). Furthermore, the device has a wall (26), from which the potting compound (22) can detach.