Motor Vehicle Sensor Overmolding for Precise Magnet Alignment
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Solution Overview
Problem
Existing sensor manufacturing methods result in variations in the positioning of the magnet relative to the measurement cells, leading to inaccurate measurements due to high tolerance ranges, causing inconsistent signals for the same measurement configuration across different sensors.
Innovation Solution
A method involving a mold with lateral indentations that retain the lead frame and magnet during overmolding, ensuring precise longitudinal and transverse locking, allowing for consistent positioning and reducing tolerance, thereby achieving high accuracy in sensor measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the magnet is positioned on the overmolded integrated circuit without lateral retention, then the manufacturing process is simpler, but the positioning precision of the magnet relative to the measurement cells varies from one sensor to another
Solution Approach 1:
The mold is divided into multiple sections including a lower mold half, lateral mold halves, and an upper mold half. The lateral mold halves incorporate lateral retention members that segment the retention function from the general overmolding process, enabling precise magnet positioning while maintaining manufacturing efficiency.
Solution Approach 2:
The lateral retention members are pre-positioned in the lateral mold halves before the overmolding process begins. This preliminary positioning ensures that when the magnet is placed on the integrated circuit, it is automatically retained in the correct position relative to the measurement cells, eliminating positioning variations between sensors.
2Measurement precision
If lateral retention members are used to lock the magnet during overmolding, then the magnet positioning consistency is improved, but the device complexity increases
Solution Approach 1:
The lateral retention members are integrated into the lateral mold halves, combining the retention function with the molding structure. This merging ensures that the magnet is locked in position during overmolding without requiring separate retention mechanisms, thereby improving measurement precision while controlling device complexity.
Solution Approach 2:
The lateral retention members serve multiple functions: they retain the magnet during overmolding, define the magnet's position relative to the integrated circuit, and ensure consistent positioning across all sensors. This multi-functionality improves measurement precision without proportionally increasing device complexity.
3Manufacturing precision
If the magnet is positioned without lateral locking during overmolding, then the manufacturing process is simpler, but the tolerance range is high leading to inaccurate measurements
Solution Approach 1:
The lateral retention members are pre-installed in the lateral mold halves before the overmolding process. This preliminary action ensures that when the magnet is placed on the integrated circuit, it is automatically positioned with high precision relative to the measurement cells, eliminating the need for complex post-positioning adjustments.
Solution Approach 2:
The lateral retention members act as intermediaries between the lateral mold halves and the magnet. They transfer the positioning precision of the mold structure to the magnet, ensuring accurate positioning relative to the measurement cells while simplifying the overall manufacturing process by eliminating the need for complex alignment procedures.
Data Source
AI summary
A method for manufacturing a sensor for a motor vehicle. The method includes placing a sensor core in a lower indentation of a mold; the sensor core having a metal lead frame, including connection pins and lateral retention members, and an integrated circuit, including at least one measurement cell and being overmolded on a support zone of the metal lead frame so the lateral retention members and the connection pins are exposed, and an electrically conductive terminal on each connection pin; placing a magnet in line with the overmolded integrated circuit; placing two lateral indentations of the mold on either side of the magnet and the integrated circuit so the lateral indentations retain the lead frame in the vicinity of the lateral retention members; overmolding the integrated circuit, the magnet and part of the lead frame to allow the free end of the terminals to project; and removing the mold.