Stacked Motor Control PCBs With Board-to-Board Connector Assembly
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Solution Overview
Problem
The existing electric drive devices face challenges with miniaturization and cost reduction due to large terminal pitches, increased assembly steps, and vulnerability to breakage from lead frame terminals, and higher production costs with flexible terminals.
Innovation Solution
An electric drive device with first and second circuit boards stacked with a space between them, where a plug connector on one board and a receptacle connector on the other form a board-to-board connector for electrical connection, allowing simultaneous assembly and reducing the need for soldering and terminal connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If lead frame terminals are used to connect circuit boards, then electrical connection is established, but the board occupying area becomes large due to large terminal pitches
Solution Approach 1:
The patent transitions from planar terminal connections to three-dimensional stacked board connections. Multiple circuit boards are stacked in the vertical direction with connectors extending between them, utilizing the third dimension (height/depth) to establish electrical connections without increasing the horizontal board area. This resolves the contradiction by reducing board occupying area while maintaining connection reliability through the stacked configuration.
2Ease of manufacture
If lead frame terminals are used to connect circuit boards, then electrical connection is established, but the number of assembling process steps increases with the need to perform soldering operation on each terminal
Solution Approach 1:
The patent merges multiple separate connection operations into a single integrated assembly process. The stacked board configuration with built-in connectors allows electrical connections between multiple circuit boards to be established simultaneously in one assembly step, eliminating the need for separate soldering operations on each terminal. This reduces assembly complexity while maintaining connection reliability through the integrated connector design.
3Reliability
If lead frame terminals are used to connect circuit boards, then electrical connection is established, but the terminal has a fear of breakage by resonance because of its elongated terminal shape
Solution Approach 1:
The patent segments the connector structure into multiple independent connection points distributed across stacked boards. Instead of using single elongated terminals that are susceptible to resonance, the connection is divided into multiple shorter terminal segments arranged vertically across different board layers. This segmentation reduces the effective length of each terminal, minimizing resonance vulnerability while maintaining overall connection reliability.
4Ease of manufacture
If flexible terminals are used to connect circuit boards, then electrical connection is established, but the production cost increases with increase in the number of assembling process steps
Solution Approach 1:
The patent incorporates connectors directly into the circuit board structure during board manufacturing, rather than adding them as separate components during assembly. The plug and receptacle connectors are pre-installed and positioned on the boards before stacking, eliminating the need for additional assembly steps. This preliminary action reduces production cost by eliminating extra manufacturing processes while maintaining high assembly speed through the pre-configured connector arrangement.
Data Source
AI summary
A first circuit board 16 and a second circuit board 17, each of which have mounted thereon circuit components for controlling and driving an electric motor, are stacked with a space left therebetween such that one board surface of the first circuit board and one board surface of the second circuit board are opposed to and face each other in the direction of a rotation shaft 14 of the electric motor. In a state that the first circuit board 16 and the second circuit board 17 are attached to the motor housing, a receptacle connector 28 mounted on the first circuit board and a plug connector 34 mounted on the second circuit board form a “board-to-board connector” by which the circuit components of the first and second circuit boards are electrically connected.