Polysiloxane Film for Water-Resistant Electronic Contacts
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Solution Overview
Problem
Current protective films for electronic devices are inadequate in providing comprehensive water protection, often resulting in incomplete encapsulation, contamination of electrical contact zones, and functional failures due to high impedance and corrosion issues, especially when thick or made with large molecular weight materials like parylene and cross-linked fluoroacrylates.
Innovation Solution
A polysiloxane film with Si—O bonds, formed by polymerizing specific siloxane monomers, is applied using a plasma-enhanced chemical vapor deposition process, which provides a thickness of 0.3 to 1.5 microns, passing corrosion current and contact resistance tests, and offering improved water resistance and mechanical compliance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a thick protective film is applied to provide better water protection, then water resistance is improved, but electrical contact zones become contaminated and impedance increases
Solution Approach 1:
The patent applies different properties to different regions of the protective film. The film is designed to be selectively permeable, allowing it to block water and ions while permitting electrical current passage. This local differentiation of protective and conductive properties resolves the contradiction between water resistance and electrical contact reliability.
Solution Approach 2:
The protective film is constructed as a composite material combining hydrophobic polymeric material with conductive elements or structures. This composite structure enables the film to simultaneously provide water protection through its hydrophobic properties and maintain electrical conductivity through embedded conductive pathways, thus resolving the contradiction between these two opposing requirements.
2Strength
If a protective film with high molecular weight material like parylene is used, then mechanical strength is improved, but incomplete encapsulation and corrosion issues occur
Solution Approach 1:
The patent modifies the physical and chemical parameters of the protective film, including its molecular weight, cross-linking density, and surface energy characteristics. By optimizing these parameters, the film achieves both adequate mechanical strength and complete encapsulation capability, preventing corrosion while maintaining structural integrity.
Solution Approach 2:
The patent employs a flexible thin film structure that can conformally coat complex electronic component geometries. This flexible film design ensures complete encapsulation of all surfaces and crevices, preventing corrosion ingress while maintaining the mechanical protection needed, thus resolving the contradiction between strength and encapsulation completeness.
3Object-affected harmful factors
If a protective film is applied to seal interfaces, then protection from moisture ingress is improved, but mechanical compliance is reduced
Solution Approach 1:
The patent utilizes a flexible thin film that can accommodate mechanical deformations and thermal expansions while maintaining the seal. The film's flexibility allows it to comply with the mechanical movements of connected components, preventing moisture ingress without restricting necessary mechanical compliance.
Solution Approach 2:
The protective film is designed with dynamic properties that allow it to adapt to changing mechanical conditions. The film can deform, flex, and recover in response to thermal cycling and mechanical stress, maintaining its sealing function while accommodating the dynamic mechanical behavior of the connected components.
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 polysiloxane film effectively prevents water ingress and ion conduction, providing up to IPx7 protection while maintaining electrical contact and mechanical robustness, significantly reducing corrosion and functional failures compared to existing films.
Implementation Method 1
The plasma process applies charges to the surface of the substrate so molecular fragments of the fluorohydrocarbon monomers created by the plasma, or pulsed plasma, may be bonded to the charged surface.
Implementation Method 2
The film may be deposited by plasma-assisted chemical vapor deposition of fluorohydrocarbon monomers onto at least part of the substrate surface.
Implementation Method 3
These references describe the application of a hydrophobic polymeric film having a thickness between at least one to ten microns (1-10 μm) around electronic components on substrate assemblies.
Data Source
AI summary
A polysiloxane film comprises Si—O bonds and has a thickness of 0.3 to 1.5 microns. Adjacent electrodes coated with the polysiloxane film have a leakage current of at most 0.01 mA at 10 V after contact with water. An electrode coated with the polysiloxane film has a contact resistance of at least 0.01 ohms at 1.0 mm of pogo pin compression under a 1.0 N load. The polysiloxane film provides IPx7 protection from ingress of water.