Sealed Circuit Card Assembly Dual-Layer Protection
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Solution Overview
Problem
Conventional wire bundle assemblies in harsh environments, such as aircraft brake systems, are susceptible to moisture ingress and corrosion due to their susceptibility to failure under extreme conditions like varying temperatures and pressures, leading to potential damage of active circuit cards.
Innovation Solution
A method involving the encapsulation of circuit card assemblies within a housing using a curable liquid, followed by curing and vacuum impregnation with a sealant to form a dual-layer protective composition, where a first cured material provides mechanical retention and primary sealing, and a second cured material occupies porosity and interfaces to enhance sealing and flexibility, preventing moisture ingress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional wire bundle assemblies are used in harsh environments, then the system can operate under extreme conditions, but moisture ingress and corrosion occur leading to circuit card failure
Solution Approach 1:
The patent implements a nested protective structure where the circuit card assembly is first potted within a housing using curable liquid encapsulant, then the entire assembly is vacuum impregnated with sealant that penetrates and seals the potting material. This multi-layer nested approach creates progressive barriers against moisture ingress, with each layer providing additional protection while maintaining structural integrity in harsh environments
Solution Approach 2:
The patent combines two different curable liquids with complementary properties: a first curable liquid (encapsulant) that provides mechanical retention and structural support, and a second curable liquid (sealant) that provides enhanced moisture barrier properties. This composite material approach leverages the strengths of each material to achieve both structural integrity and superior moisture protection
2Ease of manufacture
If a single-layer protective coating is applied to the circuit card, then the manufacturing process is simple, but the sealing effectiveness against moisture is insufficient
Solution Approach 1:
The protective system is segmented into distinct functional layers: the first curable liquid provides mechanical retention and primary encapsulation, while the second curable liquid provides secondary sealing through vacuum impregnation. This segmentation allows each layer to be optimized for its specific function while maintaining a relatively simple two-step manufacturing process
Solution Approach 2:
The first curable liquid is applied and cured before the second curable liquid is introduced. This preliminary action creates a structured matrix that guides the vacuum impregnation process, ensuring the sealant penetrates to all critical interfaces and porosity regions before final curing occurs
3Strength
If the circuit card assembly is fully encapsulated in rigid material, then mechanical strength is improved, but flexibility and stress absorption are reduced
Solution Approach 1:
The patent applies different material properties to different regions and functions: the first curable liquid provides rigid structural support and mechanical retention, while the second curable liquid penetrates porosity and interfaces to provide flexible sealing. This local differentiation of material properties allows the assembly to simultaneously achieve mechanical strength and flexibility where needed
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 dual-layer protective composition effectively inhibits moisture ingress and mechanical stress, enhancing the durability and reliability of circuit card assemblies in harsh environments by providing both primary sealing and flexibility, thus preventing corrosion and structural failure.
Implementation Method 1
at least partially filling the volume with a curable liquid such that the curable liquid encapsulates at least a circuit card of the circuit card assembly
Implementation Method 2
after at least partially filling the volume with the curable liquid and after curing the curable liquid, vacuum impregnating the potted circuit card assembly with a sealant
Implementation Method 3
vacuum impregnating the potted circuit card assembly with a sealant to seal any exposed interfaces or cracks
Data Source
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AI summary
A method of manufacturing a sealed circuit card assembly includes disposing a circuit card assembly (112) within a volume defined by a housing (111) and at least partially filling the volume with a curable liquid such that the curable liquid encapsulates at least a circuit card (113). The method may also include curing the curable liquid to form a potted circuit card assembly and, after at least partially filling the volume with the curable liquid and after curing the curable liquid, vacuum impregnating the potted circuit card assembly with a sealant to seal any exposed interfaces or cracks to form the sealed circuit card assembly. Accordingly, the sealed circuit card assembly may include a first cured material encapsulating the circuit card (113) of the circuit card assembly (112) and a second cured material disposed within, for example, a porosity of the first cured material.