Molded PCB Encapsulation for Water-Resistant Battery Packs
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Solution Overview
Problem
Existing electric devices, such as battery packs, face challenges in protecting their printed circuit boards (PCBs) from debris and water ingress, which can lead to corrosion and damage, and require manual masking with conformal coatings that are not always effective.
Innovation Solution
The solution involves molding plastic onto at least a portion of the PCB and battery cells within the battery pack housing, using processes like low-pressure over molding or multi-shot molding, to create a protective plastic body that acts as a water-resistant barrier and eliminates the need for conformal coatings, while ensuring precise protection and improved thermal performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If manual masking with conformal coatings is used to protect PCB, then protection from debris and water is provided, but the coating is not always effective and requires manual application
Solution Approach 1:
The patent replaces the mechanical manual masking process with an automated injection molding system. Molten plastic is injected under pressure to form a protective body that encapsulates the PCB, eliminating the need for manual masking and conformal coating application while providing more reliable protection.
Solution Approach 2:
The patent uses a composite structure where a plastic body is formed by injecting molten plastic that encapsulates the PCB. This composite protective body integrates structural support and environmental protection functions, providing more effective shielding against debris and water compared to thin conformal coatings.
2Productivity
If plastic is injected at high pressure to form protective body, then manufacturing efficiency is improved, but risk of damaging electrical components increases
Solution Approach 1:
The patent applies preliminary action by first masking sensitive electrical components before injecting the molten plastic. This preparatory step protects vulnerable areas from the high-pressure injection process while allowing efficient molding of the protective body.
Solution Approach 2:
The patent controls the injection pressure parameter within a specific range (at least 50 psi) to balance manufacturing efficiency with component safety. The pressure is sufficient to form a complete protective body but controlled to prevent damage to electrical components.
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 effectively prevents debris and water from reaching the electrical components, reduces the risk of corrosion, and enhances manufacturing efficiency by eliminating the need for manual masking, while improving thermal performance and reliability of the battery pack.
Implementation Method 1
The plastic is injected into the cavity at a pressure of at least 50 psi
Data Source
AI summary
An electric device includes a housing, a printed circuit board disposed in the housing, and plastic molded onto at least a portion of the printed circuit board.