Embedded PCB Busbars for Vibration-Resistant Power Tool Motors
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Solution Overview
Problem
Solder connections between wires and printed circuit boards in power tools are prone to breakage due to vibrations, leading to unreliable electrical connections.
Innovation Solution
Embedding busbars between layers of the printed circuit board to provide a more robust electrical connection between the stator terminals and the PCB, using switches like FETs or MOSFETs, with ends of the busbars extending radially or being connected via screws or welding for enhanced stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solder connections are used to connect wires to the PCB, then the electrical connection can be established, but the connection is prone to breakage from vibrations
Solution Approach 1:
The patent merges the wire connection function directly into the PCB by embedding busbars within the PCB structure. The busbars are integrated between PCB layers and extend to contact surfaces, eliminating the need for separate wire soldering operations. This integration creates a unified structure where the electrical connection is inherent to the PCB itself, thereby improving reliability by removing the vulnerable solder joint interface.
Solution Approach 2:
The patent transitions from a surface-level wire soldering approach to a multi-dimensional embedded busbar structure. The busbars are positioned between PCB layers (internal dimension) and extend to external contact surfaces (external dimension), creating a three-dimensional connection architecture. This dimensional transformation provides mechanical reinforcement against vibration while maintaining electrical connectivity.
2Reliability
If embedded busbars are used instead of soldered wires, then vibration resistance improves, but manufacturing complexity increases
Solution Approach 1:
The busbars are pre-positioned and embedded within the PCB structure during PCB manufacturing, before final assembly. This preliminary integration allows the busbars to be securely anchored between layers and connected to internal circuit traces in advance, creating a robust embedded structure that can withstand subsequent assembly operations and usage vibrations without requiring additional reinforcement steps.
Solution Approach 2:
The embedded busbars serve as intermediaries between the external contact surfaces and the internal PCB circuitry. By positioning the busbars within the PCB structure rather than on the surface, they act as a mediating element that transfers electrical and mechanical loads through the PCB thickness, distributing stress and improving vibration resistance while maintaining electrical functionality.
Data Source
AI summary
A power tool that includes a motor and a printed circuit board (“PCB”). The motor includes a rotor and a stator. The stator includes a plurality of stator terminals. The PCB is electrically connected to the stator. The PCB includes a switch and an embedded busbar. A first end of the embedded busbar is electrically connected to the switch. The embedded busbar extends away from the PCB. A second end of the embedded busbar electrically connects to a stator terminal of the plurality of stator terminals for providing power to the motor using the switch. The embedded bus bar is embedded between two layers of the printed circuit board.