Overmolded Electronic Module Flexible Circuit Pigtail Protection
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Solution Overview
Problem
Existing overmolded electronic modules lack a reliable method to integrate a flexible circuit pigtail, which is essential for applications requiring environmental sealing and protection from mechanical and thermal damage during the overmolding process.
Innovation Solution
The method involves fixturing the electronic assembly with a flexible circuit in a mold cavity, using a compressible elastomeric interface to seal and protect the circuit from clamping forces, and applying a pre-mold coating for adhesion, along with a heat exchanger to manage thermal stress, ensuring the flexible circuit is securely encapsulated within a plastic resin housing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the flexible circuit is directly placed in the mold cavity for overmolding, then the molding process can be simplified, but the flexible circuit is damaged due to clamping force and thermal conduction from the mold
Solution Approach 1:
A compressible elastomeric material is introduced as an intermediary between the mold and the flexible circuit. This elastomeric material absorbs the clamping force during molding and provides thermal insulation, preventing both mechanical damage and thermal conduction to the flexible circuit while allowing the molding process to proceed
Solution Approach 2:
The elastomeric material is positioned in advance between the mold and the flexible circuit to provide cushioning protection before the molding process begins. This pre-positioned cushioning material prevents direct transmission of harmful forces and heat during the molding operation
2Ease of operation
If the flexible circuit is exposed at the mold surface for electrical access, then electrical connection is enabled, but the flexible circuit is exposed to mechanical damage and thermal stress
Solution Approach 1:
The elastomeric material is selectively positioned only at the exposed portion of the flexible circuit where it protrudes from the mold. This localized protection provides mechanical cushioning and thermal insulation precisely where the circuit is most vulnerable, while maintaining electrical access functionality
Solution Approach 2:
The compressible elastomeric material acts as a flexible protective layer around the exposed flexible circuit. This flexible shell provides mechanical protection and thermal insulation while allowing the circuit to maintain its flexibility and electrical connection capability
3Reliability
If the flexible circuit is fully encapsulated for environmental sealing, then environmental protection is improved, but electrical access to the circuit board becomes difficult
Solution Approach 1:
The flexible circuit is segmented into two functional zones: an exposed portion that protrudes from the mold for electrical access and connection, and an encapsulated portion that is surrounded by the elastomeric material and molding compound for environmental sealing. This segmentation allows both electrical access and environmental protection to coexist
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
This approach provides a durable and reliable overmolded electronic module with a flexible circuit pigtail, ensuring adequate sealing, mechanical protection, and thermal management, thereby enhancing the module's reliability and durability.
Implementation Method 1
a compressible elastomeric interface between the mold and the flexible circuit seals off the mold cavity and protects the flexible circuit from damage due to the clamping force of the mold
Implementation Method 2
The portion of the flexible circuit within the mold cavity is pre-coated with a material that ensures good adhesion with the molding compound
Implementation Method 3
a heat exchanger thermally coupled to the portion of the flexible circuit that protrudes from the mold protects the flexible circuit from damage due to thermal conduction from the mold and mold compound
Data Source
AI summary
A method of producing an overmolded electronic assembly including a circuit board and a flexible circuit interconnect by fixturing the assembly in a mold cavity such that a portion of the flexible circuit protrudes from the mold, and providing a compressible elastomeric interface between the mold and the flexible circuit to seal off the mold cavity and protect the flexible circuit from damage due to the clamping force of the mold. The portion of the flexible circuit within the mold cavity is pre-coated with a material that ensures good adhesion with the molding compound, and a heat exchanger thermally coupled to the portion of the flexible circuit that protrudes from the mold protects the flexible circuit from damage due to thermal conduction from the mold and mold compound.