Power Tool Battery Pack Circuit Board Slit Design
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Solution Overview
Problem
Power tool battery packs are vulnerable to electrical connections between signal terminals due to water exposure, leading to improper operation, and existing coatings like low temperature, low pressure molding resin are insufficient in preventing such connections.
Innovation Solution
Incorporating a slit or insulating material between signal terminals on the circuit board to create a gap that prevents electrical connection, even if water contacts the terminals, and using a resin member to cover and isolate the signal terminals from water.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If signal terminals are disposed adjacently on the circuit board, then the battery pack structure is compact and simple, but water droplets can electrically connect adjacent terminals causing improper operation
Solution Approach 1:
The circuit board is segmented by cutting slits between adjacent signal terminals, creating physical separation that prevents water droplets from bridging multiple terminals. This segmentation maintains the compact overall structure while eliminating the electrical connection risk between terminals.
Solution Approach 2:
An insulating material is introduced as an intermediary substance between adjacent signal terminals on the circuit board. This insulating layer acts as a mediator that prevents electrical connection through water droplets while allowing the terminals to remain adjacently disposed for compact design.
2Ease of manufacture
If signal terminals are coated with low temperature low pressure molding resin, then some protection is provided, but the coating is insufficient to prevent electrical connection through water
Solution Approach 1:
Slits are cut into the circuit board before final assembly, creating pre-established physical barriers between terminals. This preliminary action ensures that even before any coating is applied, the terminals are structurally separated to prevent water-induced electrical connection.
Solution Approach 2:
The solution combines multiple protective approaches: physical slits in the circuit board combined with insulating material coating. This composite protection method is more effective than using either method alone, providing both structural separation and material-based insulation.
Data Source
AI summary
A power tool battery pack includes a lower side case, an upper side case fixed to the lower side case, a battery cell in the lower side case and a circuit board connected to the battery cell. A plurality of electrical signal terminals are arranged in parallel on the circuit board, and the circuit board includes at least one slit between adjacent pairs of the plurality of signal terminals to make it difficult for any water that reaches the circuit board to electrically short two of the signal terminals together. Alternately or in addition, a wall structure may be provided between the terminals for reducing the likelihood that water reaching one of the signal terminals will be able to electrically connect two of the signal terminals.