IC Peripheral Conductive Layers for RF-Resistant Optical Sensors
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Solution Overview
Problem
Analog integrated circuits and sensors are susceptible to severe errors and communication failures due to intense radio frequency interference from adjacent RF antennas, which existing shielding techniques, such as metal boxes, cannot effectively mitigate without obstructing external light for optical sensors.
Innovation Solution
An integrated circuit chip mounted on a ground plane with electrically conductive layers encircling its periphery and additional bondwires electrically coupled to the ground plane, forming low impedance loops that induce an opposing magnetic field to counteract RF interference while allowing light to be sensed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a metal box surrounding the integrated circuit is used for shielding, then RF interference is blocked, but external light cannot reach the optical sensor
Solution Approach 1:
The shielding structure is segmented into multiple functional layers: conductive layers encircling the chip periphery for RF shielding, and light-transmissive regions for optical sensor access. This segmentation allows different parts of the package to perform different functions - blocking RF interference while permitting light transmission to the optical sensor.
Solution Approach 2:
Different regions of the package have different shielding properties. The sides and bottom of the package have conductive shielding layers for RF protection, while the top region has light-transmissive properties to allow optical sensor operation. This local differentiation of shielding quality resolves the contradiction between RF blocking and light transmission.
2Object-affected harmful factors
If conventional shielding techniques are used, then RF interference is reduced, but the cost increases due to metal enclosures
Solution Approach 1:
The package structure performs multiple functions simultaneously: the conductive layers provide RF shielding, the bondwires provide electrical connections, and the overall structure provides mechanical support. This multi-functionality eliminates the need for separate expensive metal enclosures, reducing manufacturing cost while maintaining RF interference protection.
Solution Approach 2:
Instead of using expensive metal enclosures, the invention uses a simplified package structure with conductive layers and bondwires that replicates the essential shielding function. This copying approach achieves the same RF protection effect at lower cost by using existing package components in a shielding configuration.
3Reliability
If the integrated circuit is exposed to intense magnetic and electric fields for EMC testing, then communication reliability is improved, but analog circuit errors increase
Solution Approach 1:
The conductive layers and bondwire configuration are designed in advance to counteract the effects of intense magnetic and electric fields during EMC testing. The low-impedance loops formed by the bondwires and conductive layers induce opposing magnetic fields that preemptively counteract the interfering fields, preventing analog circuit errors before they occur.
Solution Approach 2:
The patent converts the harmful effect of intense magnetic fields into a beneficial shielding mechanism. The same magnetic fields that could cause errors are utilized to induce currents in the conductive loops, which then generate opposing magnetic fields that protect the analog circuits. This transforms the harmful RF interference into a protective shielding effect.
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
Significantly reduces RF interference, minimizing errors in analog circuits and communication failures, particularly for optical sensors, without the need for expensive metal enclosures, as demonstrated by TEM Cell test results showing a delta count reduction to approximately 0.1% of the raw count.
Implementation Method 1
forming low impedance loops that induce an opposing magnetic field to counteract RF interference
Data Source
AI summary
An apparatus comprises a ground plane (2), an integrated circuit chip (1) disposed on the ground plane (2), the integrated circuit chip (1) comprising one or more electrically conductive layers (10) encircling a periphery of the integrated circuit chip (1), and a plurality of bondwires (9) electrically coupling the one or more electrically conductive layers (10) to the ground plane (2).