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The internal electronic connectivity requirements of electric toothbrushes vary significantly based on their technical threshold (e.g., standard vibration vs. high-end maglev motors) and charging methods (wireless induction vs. USB-C direct charging).
Given that electric toothbrushes are high-frequency vibrating consumer electronics that require strict waterproofing, their internal wiring and connectors must prioritize vibration fatigue resistance and space optimization.
Below is a translation of the common applications for connectors and wiring in electric toothbrushes:
1. Internal Wiring Applications
￭ Enamelled Copper Wire
Application: Used for the wireless charging secondary coil at the base.
Features: Due to extreme space constraints, the coil is usually soldered directly onto the PCB. The connection point between the coil windings and the circuit board is the most common failure point (fracture) during long-term use.
￭ Silicone Wire or Fine Electronic Wire
Application: Connects the battery to the PCB and the motor to the PCB.
Features: Battery leads are typically required to be highly flexible to facilitate cable routing within the narrow cylindrical housing during assembly.
￭ Flexible Printed Circuit (FPC)
Application: Used in high-end smart toothbrushes to connect LED display panels, pressure sensors, or Bluetooth modules.
Features: Saves space and conforms to the internal curvature of the toothbrush's cylindrical body.
2. Connectors
￭ Board-to-Board (BTB) Connectors
If the toothbrush utilizes a dual-board design (e.g., separating the main controller from the button/indicator board), miniature BTB connectors are used for interconnection.
￭ USB-C Connectors
Application: Found in non-wireless (fast-charging) models, located at the base.
Technical Focus: Must achieve an IPX7 waterproof rating, typically utilizing mid-mount (sink-type) designs or waterproof sealing gaskets.
￭ Battery Tabs / Contact Springs
To facilitate automated production, many designs replace wires with nickel tabs (spot-welded) or metal contact springs to secure and connect 14500 Li-ion or Ni-MH batteries to the PCB via a plastic frame.
￭ Motor Terminals
For ease of assembly or repair, some designs use miniature pluggable terminals between the motor and PCB. However, most low-cost solutions prefer hard-wiring (direct soldering) to reduce costs and minimize the risk of loosening caused by vibration.
3. Specialized Manufacturing Processes
Since sonic toothbrushes generate over 30,000 vibrations per minute, connection points often require additional reinforcement:
￭ Dispensing (Potting/Gluing): Applying RTV silicone or UV glue over solder joints (such as coil leads and motor terminals) to prevent solder joint peeling due to vibration fatigue.
￭ Heat Shrink Tubing: Used to protect battery leads and prevent insulation wear within the tightly packed internal space.