Hall Sensor Package With Internal Magnetic Shielding Layout
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Solution Overview
Problem
Existing semiconductor devices with Hall sensors face challenges in integrating magnetic shields during manufacturing, leading to high costs and susceptibility to stray magnetic fields, which affect current measurements.
Innovation Solution
A semiconductor device package design that includes a first magnetic shield mounted to the package substrate with a die mount area exposed and a second magnetic shield with a cantilever portion over the Hall element, combined with a heat slug for current conduction, all encapsulated in a mold compound to form a thermal pad.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If magnetic shields are integrated using semiconductor device processing, then magnetic shielding performance is improved, but manufacturing cost increases and manufacturing complexity increases
Solution Approach 1:
The magnetic shield is divided into separate components (first magnetic shield portion and second magnetic shield portion) that are attached to different surfaces of the semiconductor device package, rather than attempting to integrate a single complex shield structure during semiconductor processing. This segmentation allows each portion to be manufactured independently and attached separately, reducing overall manufacturing complexity and cost while maintaining shielding effectiveness.
Solution Approach 2:
The magnetic shield is transitioned from a planar structure to a three-dimensional structure by attaching portions to both the first surface and the second surface of the package substrate. This dimensional approach creates a more effective shielding enclosure around the Hall sensor without requiring complex integration during semiconductor fabrication, thereby improving shielding performance without proportionally increasing manufacturing difficulty.
2Reliability
If custom semiconductor packages are used for Hall sensors, then magnetic shielding and sensor integration are improved, but assembly cost increases due to non-standard footprints
Solution Approach 1:
The package substrate is designed with a standard footprint that can accommodate the Hall sensor die, magnetic shield portions, and electrical connections in a universal configuration. This standardized design allows the same package substrate to be used across different Hall sensor applications, enabling economies of scale in manufacturing and reducing assembly costs while maintaining effective sensor integration and magnetic shielding.
3Measurement precision
If magnetic shields are added to protect Hall sensor, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The magnetic shield is segmented into multiple portions that are attached to different surfaces of the package substrate. This segmentation allows each portion to perform a specific shielding function (blocking magnetic fields from different directions) while keeping the individual components simple and easy to manufacture, thereby improving measurement precision without proportionally increasing overall device complexity.
Solution Approach 2:
The package substrate serves as an intermediary structure that holds both the Hall sensor die and the magnetic shield portions in precise relative positions. This intermediary approach simplifies the overall device structure by providing a single platform for mounting multiple components, reducing the complexity that would otherwise arise from trying to directly integrate shields with the sensor die.
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 design provides effective magnetic shielding, reducing measurement errors from stray fields while maintaining a standard package footprint, thus lowering assembly costs and improving performance.
Implementation Method 1
Hall effect sensors with circuitry. Magnetic sensing can be used for motor control, position sensing, automation, current sensing and other applications. Hall effect sensors integrated in semiconductor devices can be formed by doping regions to include carriers that are sensitive to a magnetic field. A voltage proportional to a magnetic field is output by the Hall sensor while a current is applied to the Hall sensor.
Implementation Method 2
An aspect of a Hall sensor is the need for magnetic shielding. Because the Hall sensor uses a magnetic field caused by a current flowing through a metal conductor to sense the current, stray magnetic fields in the environment can adversely impact sensing and result in error in the current measurements. To improve performance, magnetic shielding and magnetic concentrators are used.
Implementation Method 3
forming a package substrate having a board side surface and an opposite top surface, and having a heat slug coupled to the package substrate, the heat slug configured to conduct a current between terminals of the package substrate
Data Source
AI summary
A described example includes: a heat slug coupled to a package substrate, the heat slug configured to conduct a current between terminals of the package substrate; a first magnetic shield mounted to a top surface of the package substrate, the first magnetic shield including a die mount area; a semiconductor die flip chip mounted to the die mount area; a second magnetic shield mounted to the package substrate, the second magnetic shield having a cantilever portion extending over a portion of the semiconductor die including a Hall element; electrical connections of wire bonds or ribbon bonds between bond pads of the semiconductor die and leads on the package substrate; and mold compound covering the electrical connections, the semiconductor die, the first magnetic shield, and the second magnetic shield, while a portion of the heat slug is exposed forming a thermal pad for a semiconductor device package.