Encapsulated Circuit Device With Absorption Layer for Thermal Stress Management
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Solution Overview
Problem
Substrate-based circuits face mechanical stresses due to thermal expansion differences between materials, leading to unreliable electrical contacts and component damage, particularly in high-temperature applications like the automotive sector, where temperature fluctuations are significant.
Innovation Solution
A circuit device with a rigid outer encapsulation and a compressible absorption layer that absorbs thermal stresses, preventing direct contact between the encapsulation and voltage-sensitive components, and allowing for significant deformation to absorb volume changes without exerting pressure on the circuit, thus reducing mechanical stresses and maintaining reliability across wide temperature ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rigid outer encapsulation is used to protect the circuit, then mechanical stability and protection against external influences are improved, but mechanical stresses arise due to thermal expansion differences between materials
Solution Approach 1:
A compliant absorption layer is introduced as an intermediary between the rigid outer encapsulation and the circuit substrate. This absorption layer has a lower modulus of elasticity than the rigid encapsulation, allowing it to deform and absorb thermal expansion stresses while protecting the circuit components from mechanical stress transmission.
Solution Approach 2:
The patent changes the mechanical parameter (modulus of elasticity) of the absorption layer to be lower than that of the rigid encapsulation. This parameter difference enables the absorption layer to deform under thermal stress, accommodating differential thermal expansion between the circuit materials and the rigid housing without transmitting harmful stresses to the components.
2Strength
If the encapsulation is made rigid for mechanical stability, then structural strength is improved, but gaps and unreliable electrical contacts occur due to thermal expansion differences
Solution Approach 1:
The compliant absorption layer acts as a stress-absorbing intermediary that prevents direct rigid contact between the encapsulation and circuit components. This layer deforms to accommodate thermal expansion, preventing gap formation and maintaining reliable electrical contacts while the rigid encapsulation provides overall structural strength.
3Adaptability or versatility
If components are mounted on a substrate with large dimensions, then functional capability is improved, but mechanical stresses increase due to large enclosed volume during temperature changes
Solution Approach 1:
The patent utilizes the parameter difference in modulus of elasticity between the absorption layer and rigid encapsulation to enable the absorption layer to deform and absorb thermal stresses. This allows large-dimension circuits to be enclosed without transmitting harmful mechanical stresses to the components, as the absorption layer accommodates the volume changes during temperature variations.
4Reliability
If a housing is added to protect the circuit, then protection against environmental influences is improved, but space requirement increases
Solution Approach 1:
The patent uses a thin compliant absorption layer instead of a thick rigid buffer zone. This absorption layer provides the necessary stress absorption and protection functions while occupying minimal space, allowing the overall housing volume to remain compact while still providing environmental protection and stress management.
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
The solution significantly reduces mechanical stresses by orders of magnitude with minimal additional space requirement, ensuring reliable operation across wide temperature ranges and strong spatial temperature gradients, allowing heat-generating components to coexist with lower-temperature components without gaps or mechanical issues.
Implementation Method 1
materials with different properties, in particular with different coefficients of thermal expansion, collide. In particular, because the thermal expansion coefficient of the substrate differs from that of the surrounding housing material
Implementation Method 2
The deformation of the absorption layer can be an elastic deformation with a spring constant or with a modulus of elasticity that is well below that of the rigid outer encapsulation
Implementation Method 3
The absorption layer is provided as a compressible absorption layer, so that thermally induced movements of the substrate surface or of the components relative to the outer encapsulation are absorbed by deformation of the absorption layer
Data Source
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AI summary
The invention relates to an encapsulated circuit device comprising a substrate and a plurality of components arranged on a substrate surface section of a component side of the substrate. The device furthermore comprises an encapsulation; at least one electrical contact with an outer section which projects from the encapsulation and an inner section which is provided in the circuit device, and which is electrically connected to the substrate. The encapsulation comprises a rigid outer encapsulation, which completely reaches around the substrate, the components and the inner section of the at least one electrical contact, and also a compressible absorption layer, which is provided between the components and the outer encapsulation and completely covers at least the substrate surface section on which the components are arranged. The absorption layer is designed to absorb at least a large proportion of the deformation that arises as a result of thermally induced movement of the substrate surface and of the components relative to the outer encapsulation. The invention furthermore encompasses an associated production method.