Window Assembly Conductive Compressible Member Thermal Stress
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Solution Overview
Problem
Window assemblies for vehicles experience mechanical stress and water intrusion issues due to encapsulation on solder joints, leading to cracking of transparent panes and corrosion of electrical conductors, resulting in increased failure rates.
Innovation Solution
Incorporating an electrically conductive compressible member, such as a foam material, between the electrical connection element and conductor, which absorbs thermal expansion stress and eliminates the need for solder joints, thereby preventing mechanical stress and water intrusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If encapsulation is disposed on the solder joint to attach additional components, then the additional components are securely attached to the window assembly, but the differences in coefficients of thermal expansion impart mechanical stress on the transparent pane causing cracking, delamination, or solder joint failure
Solution Approach 1:
The patent introduces a compliant undercoating layer as an intermediary between the encapsulation and the solder joint. This undercoating layer has different mechanical properties (higher compliance, different coefficient of thermal expansion) that act as a buffer to absorb thermal expansion stresses, preventing direct stress transmission to the fragile solder joint and transparent pane while still allowing the encapsulation to securely attach additional components
2Strength
If encapsulation is used to attach additional components, then the components are secured to the window assembly, but water penetrates through the encapsulation to contact the printed silver circuit near the solder joint causing corrosion and rendering the circuit inoperable
Solution Approach 1:
The compliant undercoating layer serves as an additional protective intermediary between the encapsulation and the electrical conductor. This layer creates an extra barrier that complicates water penetration pathways and provides additional protection to the printed silver circuit, reducing the risk of corrosion while still allowing the encapsulation to perform its sealing and attachment functions
3Reliability
If solder joint is used to electrically connect the printed silver circuit to the connection element, then electrical connection is established, but the solder joint is prone to cracking and failure due to mechanical stress from thermal expansion differences
Solution Approach 1:
The compliant undercoating layer acts as a stress-absorbing intermediary between the rigid encapsulation and the fragile solder joint. This layer has mechanical properties that allow it to deform and absorb thermal expansion stresses, preventing these stresses from being transmitted to the solder joint and maintaining electrical connection reliability over time
Solution Approach 2:
The patent changes the mechanical parameters of the interface between encapsulation and solder joint by introducing a layer with different compliance and elastic modulus. This parameter change transforms the rigid interface into a compliant interface that can accommodate thermal expansion differences, thereby protecting the solder joint from stress-induced cracking
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 reduces the likelihood of cracking and corrosion, making the window assembly more environmentally friendly and less prone to failure by absorbing thermal expansion stress and eliminating the need for solder, thus enhancing reliability and durability.
Implementation Method 1
the differences between the coefficients of thermal expansion of the solder joint, the transparent pane, and the encapsulation impart mechanical stress on the transparent pane
Implementation Method 2
a foam material that is compressed between said electrical connection element and said electrical conductor for providing an electrical connection
Implementation Method 3
an electrically conductive compressible member disposed between the electrical connection element and the electrical conductor, and comprising a foam material that is compressed between said electrical connection element and said electrical conductor for providing an electrical connection
Data Source
Figure 1
Figure 2
Figure 3~5
AI summary
A window assembly (10) includes a transparent pane (18), an electrical conductor (20) contacting the transparent pane (18), an electrical connection element (22) for energizing the electrical conductor (20), an encapsulation (26) disposed over the electrical connection element (22) and the electrical conductor (20), and an electrically conductive compressible member (28) disposed between the electrical connection element (22) and the electrical conductor (20) for providing an electrical connection between the electrical connection element (22) and the electrical conductor (20).