Multi-layer Plasma Conformal Coating for Electrical Assemblies
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Solution Overview
Problem
Current conformal coatings for electrical assemblies lack cost-effectiveness and do not provide sufficient moisture protection, despite offering chemical, electrical, and physical protection, with paraxylylene coatings being time-consuming and expensive to deposit.
Innovation Solution
Development of multi-layer conformal coatings using plasma deposition of organosilicon compounds with specific precursor mixtures, including reactive and non-reactive gases, to achieve enhanced chemical, electrical, and physical protection, along with improved moisture barrier properties and scratch resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If paraxylylene conformal coating is used to provide chemical, electrical and physical protection, then protection quality is improved, but manufacturing cost and time consumption increase
Solution Approach 1:
The patent changes the deposition method from conventional vapor deposition to plasma-enhanced chemical vapor deposition (PECVD), altering the process parameters to achieve comparable protection quality with improved manufacturing efficiency. The plasma activation enables lower deposition temperatures and faster coating rates while maintaining the protective properties of paraxylylene coatings.
2Reliability
If conventional conformal coating is applied to protect electrical assemblies, then basic protection is provided, but moisture barrier properties are insufficient
Solution Approach 1:
The patent divides the coating into multiple layers with different functions: a bottom layer for adhesion and basic protection, and a top layer specifically optimized for moisture barrier properties. This segmentation allows each layer to be tailored for its specific purpose, achieving superior moisture protection without excessive overall complexity.
Solution Approach 2:
The patent uses composite coating structures combining different materials - specifically paraxylylene with other polymers or inorganic layers - to achieve enhanced moisture barrier properties. The composite structure leverages the complementary properties of each material to provide superior moisture protection that neither material could achieve alone.
3Ease of manufacture
If plasma polymerization technique is used to deposit conformal coating, then alternative protection is provided, but coating hardness and scratch resistance are reduced
Solution Approach 1:
The patent applies a plasma treatment or adhesion promoter layer before depositing the final coating layer. This preliminary action creates a surface that enhances both the adhesion of subsequent layers and the overall hardness of the coating structure, compensating for the softer nature of plasma-polymerized materials.
Solution Approach 2:
The patent combines plasma-polymerized organic layers with inorganic hard coatings or cross-linked polymer layers to create a composite structure. The inorganic or highly cross-linked layers provide the required hardness and scratch resistance, while the plasma-polymerized layers provide good adhesion and flexibility, achieving a balance between manufacturing ease and mechanical strength.
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 multi-layer coatings provide superior waterproofing, increased hardness, and excellent scratch resistance, while being more cost-effective and easier to manufacture than traditional coatings, offering improved protection for electrical assemblies.
Implementation Method 1
each layer of the multi-layer coating is obtainable by plasma deposition of a precursor mixture comprising (a) one or more organosilicon compounds
Data Source
AI summary
An electrical assembly which has a multi-layer conformal coating on at least one surface of the electrical assembly, wherein each layer of the multi-layer coating is obtainable by plasma deposition of a precursor mixture comprising (a) one or more organosilicon compounds, (b) optionally 02, N2O, NO2, H2, NH3, N2, SiF4 and/or hexafluoropropylene (HFP), and (c) optionally He, Ar and/or Kr. The chemistry of the resulting plasma-deposited material chemistry can be described by the general formula: SiOxHyCzFaNb. The properties of the conformal coating are tailored by tuning the values of x, y, z, a and b.