Current Sensor Housing Alignment via Injection Mold Structures
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Solution Overview
Problem
Current sensor production methods face challenges in securely integrating Hall sensors and current conductors within a plastic housing, particularly in ensuring precise alignment and robust insulation, which affects the accuracy and reliability of the measurement.
Innovation Solution
A method involving a leadframe with integrated Hall sensors and electrical connections, where the current conductor is aligned and secured using matching structures within an injection mold, allowing for precise packaging and encapsulation within a plastic housing, and optional reinforcement with ferromagnetic sheet metal to enhance magnetic field intensity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the current conductor is guided loosely through an opening in the housing, then the manufacturing process is simple, but the alignment precision and measurement accuracy deteriorate
Solution Approach 1:
The patent applies preliminary action by pre-structuring the housing with integrated alignment features (alignment protrusions and corresponding recesses) before the current conductor is inserted. This ensures precise positioning is established in advance, eliminating the need for complex post-assembly adjustments while maintaining manufacturing simplicity.
Solution Approach 2:
The patent implements nesting by integrating the alignment structures directly into the housing body itself, rather than adding separate alignment components. The alignment protrusions and recesses are formed as integral parts of the housing during molding, creating a compact nested structure that achieves precise alignment without increasing overall device complexity.
2Device complexity
If the Hall sensor is cast directly into the housing with other components, then the device complexity is reduced, but the measurement precision and reliability deteriorate
Solution Approach 1:
The patent applies segmentation by separating the Hall sensor into a distinct, encapsulated module rather than casting it directly into the housing with other components. This modular approach allows the sensor to be pre-assembled and tested independently, then integrated into the final device with precise positioning features, thereby maintaining measurement precision while managing device complexity through modular design.
3Reliability
If reinforced insulation is implemented, then the electrical reliability is improved, but the manufacturing complexity increases
Solution Approach 1:
The patent merges the insulation function with the structural housing components themselves. The housing is designed with integrated insulation features and positioning structures that simultaneously provide mechanical support, electrical isolation, and precise alignment, thereby achieving reinforced insulation without proportionally increasing manufacturing complexity.
4Reliability
If a multi-stage encapsulation process is used to protect bonding wires, then the reliability is improved, but the production time and productivity worsen
Solution Approach 1:
The patent applies preliminary action by pre-encapsulating the bonding wires and Hall sensor into a protected module before final assembly. This preliminary encapsulation protects the delicate bonding wires during subsequent handling and assembly operations, ensuring reliability without requiring complex multi-stage encapsulation processes during final production.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method ensures accurate alignment and secure integration of Hall sensors and current conductors, improving the reliability and precision of current measurements while allowing for flexible design of current conductor sections.
Implementation Method 1
placing the leadframe in an injection mold; closing the injection mold with a first mold insert, which has a mold surface provided with structures; injecting plastic material into the injection mold in order to package each semiconductor chip and parts of the associated leadframe section in an associated intermediate housing
Implementation Method 2
connecting electrical connection surfaces of the semiconductor chips to associated connection fingers of the leadframe by bonding wires
Implementation Method 3
A Hall sensor is used as the measuring element
Implementation Method 4
optional reinforcement with ferromagnetic sheet metal to enhance magnetic field intensity
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The invention relates to a method for manufacturing current sensors that have a plastic housing produced using IC technology. The central steps consist of mounting and wiring semiconductor chips with Hall sensors onto a leadframe, placing the leadframe in an injection mold, closing the injection mold with a first mold insert, and injecting plastic material, wherein each semiconductor chip is packaged in an intermediate housing (10) that has a flat surface (11) with alignment structures. Subsequently, the injection mold is opened, and a current conductor section (15) is placed on the flat surface (11) of each intermediate housing (10). This conductor section is formed with counter-structures (14) that match the alignment structures, so that it is automatically aligned and held in place.The injection mold is then closed with a second mold insert, and plastic material is injected to form the final housing of the current sensors. Two different injection molds can also be used.