Multi-Layer Dielectric Coating for Circuit Boards
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Solution Overview
Problem
Conventional passivation techniques for circuit devices using dielectric layers like silicon-nitride and silicon-carbide are inadequate in preventing moisture degradation and increase internode capacitance, leading to performance degradation, and are susceptible to cracking and delamination, especially in non-hermetic environments.
Innovation Solution
A multi-layer dielectric coating system comprising a first protective dielectric layer with high voltage breakdown characteristics, a second layer for additional component passivation, and an optional third layer for chemical stability, made of materials such as alumina, silicon-dioxide, and parylene, applied in thin thickness to maintain performance and protect against moisture and contaminants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional dielectric layers like silicon-nitride and silicon-carbide are used for passivation, then moisture protection is provided, but internode capacitance increases and performance degrades
Solution Approach 1:
The patent divides the single thick dielectric layer into multiple thinner layers (e.g., first dielectric layer 50-200 nm, second dielectric layer 20-100 nm, third dielectric layer 10-50 nm). This segmentation reduces the overall thickness while maintaining moisture protection, thereby reducing internode capacitance and preserving circuit performance.
Solution Approach 2:
The patent uses composite dielectric materials with different properties in each layer. The first layer uses silicon-nitride or silicon-carbide for moisture barrier, the second layer uses silicon-dioxide for low capacitance, and the third layer uses parylene for chemical stability. This composite structure balances moisture protection with performance requirements.
2Object-affected harmful factors
If thick dielectric layers are used for moisture protection, then environmental protection is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent segments the thick dielectric layer into multiple thinner layers, each with controlled thickness ranges. This segmentation makes thickness control more manageable and reduces manufacturing complexity compared to depositing a single thick layer.
Solution Approach 2:
The patent changes the thickness parameters of each dielectric layer to optimize both protection and manufacturability. By specifying thickness ranges (first layer 50-200 nm, second layer 20-100 nm, third layer 10-50 nm), the patent achieves environmental protection while maintaining reasonable manufacturing complexity.
3Ease of manufacture
If conventional polymer-based conformal coatings are used, then ease of manufacture is improved, but protection against moisture and contaminants is insufficient
Solution Approach 1:
The patent replaces single polymer-based coatings with composite inorganic-dielectric layers. The combination of silicon-nitride, silicon-carbide, silicon-dioxide, and parylene provides superior moisture and contaminant protection while maintaining manufacturability through standard deposition techniques.
Solution Approach 2:
The patent changes the material composition parameters from organic polymers to inorganic dielectrics, achieving enhanced protection while maintaining ease of manufacture through established deposition processes.
4Reliability
If dielectric layers with high breakdown voltage are used, then voltage breakdown performance is improved, but the material selection and manufacturing precision requirements increase
Solution Approach 1:
The patent uses composite dielectric materials known for high breakdown voltage characteristics (silicon-nitride, silicon-carbide, silicon-dioxide, parylene). These materials provide excellent voltage breakdown performance while having well-established manufacturing processes that control quality.
Solution Approach 2:
The patent optimizes the thickness parameters of each dielectric layer to achieve the required voltage breakdown performance. By controlling each layer's thickness within specified ranges, the patent achieves high breakdown voltage while maintaining reasonable manufacturing precision requirements.
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 dielectric coating system provides superior moisture impermeability and voltage breakdown performance, reducing the thickness of dielectric layers required while maintaining circuit performance and protecting against contaminants, thus enhancing environmental protection without degrading device performance.
Implementation Method 1
capable of being deposited conformally over and under 3D structures with thickness uniformity less than or equal to 10%
Implementation Method 2
superior moisture impermeability
Data Source
AI summary
A method includes providing a circuit board having an outer surface, the outer surface configured with a plurality of discrete electrical components that are each manufactured independently of one another, and coating the outer surface and the plurality of discrete electrical components with a first protective dielectric layer. The method further includes coating the first protective dielectric layer with a second dielectric layer. The second dielectric layer includes a dielectric material having a modulus of elasticity less than 3.5 Giga-Pascal (GPa), a dielectric constant less than 2.7, a dielectric loss less than 0.002, a breakdown voltage strength in excess of 2 million volts/centimeter (MV/cm), a temperature stability to 3000 Celsius, a defect densities less than 0.5/centimeter, a pinhole free in films greater than 50 Angstroms, and is capable of being deposited conformally over and under 3D structures with thickness uniformity less than or equal to 10%.