Heterogeneous PCB Encapsulation with Localized Epoxy and Silicone
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Solution Overview
Problem
Existing encapsulation techniques for electronic components on substrates, such as printed circuit boards, lack the ability to provide tailored mechanical, electrical, and chemical protection, as they often use a single encapsulant that may not adequately address the diverse needs of different components and areas on the board, leading to potential environmental hazards and reliability issues.
Innovation Solution
Employing two or more encapsulants with different mechanical, electrical, and chemical properties on the same substrate, where a compliant silicone encapsulant is used for areas requiring flexibility and a rigid epoxy encapsulant for precise patterns and environmental sealing, allowing for customized protection of electronic components and the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single uniform encapsulant is used for all components, then the manufacturing process is simple, but the protection effectiveness is insufficient for different component requirements
Solution Approach 1:
The patent applies different encapsulant materials to different regions of the substrate based on specific component requirements. Hard epoxy encapsulant is used for components requiring rigid protection and precise patterning, while soft silicone encapsulant is used for components requiring mechanical compliance and flexibility. This local differentiation of material properties optimizes protection effectiveness for each component type without requiring a completely complex multi-layer structure throughout the entire device.
Solution Approach 2:
The patent employs composite encapsulation by combining two distinct encapsulant materials (epoxy and silicone) with different mechanical and chemical properties on the same substrate. This composite approach allows the system to leverage the advantages of both materials - the chemical resistance and structural stability of epoxy, and the flexibility and compliance of silicone - thereby improving overall reliability while maintaining a manageable structural complexity.
2Manufacturing precision
If a hard rigid encapsulant is used, then precise patterns and environmental sealing are achieved, but mechanical compliance is reduced
Solution Approach 1:
The patent strategically places hard epoxy encapsulant only in regions where precise patterns and environmental sealing are critical, such as around closely spaced components and connection interfaces. In regions requiring mechanical compliance, the patent uses soft silicone encapsulant instead. This localized application of different material properties allows the system to achieve high manufacturing precision where needed without sacrificing overall mechanical adaptability.
Solution Approach 2:
The patent changes the mechanical parameters of the encapsulant material by selecting materials with different durometer values and viscoelastic properties. The epoxy encapsulant has high rigidity and low compliance, suitable for precise patterning, while the silicone encapsulant has low rigidity and high compliance, suitable for mechanical adaptation. By changing material parameters rather than attempting to modify a single material's properties, the patent simultaneously achieves both precise patterning and mechanical compliance in different regions.
3Adaptability or versatility
If a compliant soft encapsulant is used, then mechanical flexibility is improved, but precise pattern application and environmental sealing are compromised
Solution Approach 1:
The patent restricts the use of soft silicone encapsulant to specific regions where mechanical flexibility is the primary requirement, such as areas with moving components or thermal expansion concerns. In regions requiring precise pattern application and environmental sealing, the patent uses hard epoxy encapsulant. This spatial differentiation ensures that each material's strengths are utilized where most needed, preventing the soft encapsulant from compromising pattern precision while still providing necessary mechanical flexibility elsewhere.
Solution Approach 2:
The patent creates a composite encapsulation system where the hard epoxy material provides the precise patterning and environmental sealing capabilities, while the soft silicone material provides the mechanical flexibility. The two materials work together in a coordinated manner, with each performing its specialized function, thereby achieving both precise pattern application and mechanical flexibility without either property being compromised by the other.
4Reliability
If multiple different encapsulants are used, then tailored protection for different components is achieved, but the manufacturing complexity increases
Solution Approach 1:
The patent divides the encapsulation process into distinct segments or regions, with each segment receiving a specific encapsulant material tailored to the component requirements. This segmentation allows for specialized protection of different component types while maintaining clear boundaries between application zones. The segmentation strategy simplifies manufacturing by providing clear guidelines for material application rather than requiring complex real-time adjustment of a single material system.
Solution Approach 2:
The patent implements local quality control by specifying different encapsulant materials for different regions of the substrate based on component characteristics. This approach enables tailored protection for each component type while maintaining a systematic manufacturing process. The local quality strategy reduces manufacturing complexity compared to attempting to create a universal encapsulant solution, as it provides clear material selection criteria for each region rather than requiring complex process control.
Data Source
AI summary
An improved method for producing a PCB assembly requiring at least two different encapsulants is disclosed. The PCB assembly may have two or more separate regions in which electronic devices are attached. In each region, a unique encapsulant with different mechanical, electrical, physical and or chemical properties is used according to the particular requirements of the electronic devices in that region.