Resonance Sensor for PCB Defect Detection
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Solution Overview
Problem
Current functional testing and in-circuit testing (ICT) methods are inadequate for identifying defects in modern electronic devices, particularly in PCB connectors, due to accessibility issues and high component density, leading to inefficient fault detection and significant waste.
Innovation Solution
A sensor device that detects open and short defects in electronic circuits without access points or power, using signal lines, inductors, and ground lines to determine resonance frequencies, allowing for capacitive couplings and fault identification without physical contact or powering the device under test.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional contact probe solutions (bed of nails, VTEP) are used, then fault detection capability is provided, but access points are required which are not available due to high component density and hidden soldered pins
Solution Approach 1:
The patent replaces mechanical contact probes with electromagnetic field-based sensing. The sensor device uses capacitive coupling through the PCB substrate to detect electrical defects without physical contact, substituting mechanical measurement systems with electromagnetic field interaction systems that can penetrate through the PCB structure.
Solution Approach 2:
The PCB substrate itself serves as an intermediary medium. The sensor device couples capacitively through the PCB substrate to reach the conductors and defects beneath, using the substrate as a mediator that enables detection without requiring direct access to test points or connectors.
2Measurement precision
If boundary scan technique is used, then defect detection is enabled, but the DUT must be powered up which could cause irreversible damage and the technique is unscalable to multiple connectors
Solution Approach 1:
The sensor device performs preliminary defect detection before the DUT is powered up or before irreversible damage can occur. By detecting open and short defects in conductors, connectors, and IC bond wires in advance, the system prevents potential damage that would result from powering up defective circuits.
Solution Approach 2:
The patent replaces electrical testing methods (boundary scan) that require powering the DUT with electromagnetic field-based capacitive coupling sensing. This substitution allows defect detection without injecting power into the circuit, eliminating the risk of damage while maintaining detection capability.
3Measurement precision
If ICT is used to identify components and electrical connections, then fault location precision is improved, but test access points must be available which are not accessible in modern dense PCB designs
Solution Approach 1:
The patent replaces complex mechanical test access structures (test pads, pogo pins, bed of nails fixtures) with a simplified electromagnetic sensing system. The sensor device detects defects through capacitive coupling with the PCB substrate, eliminating the need for elaborate physical access structures while maintaining fault location precision.
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
Enables efficient detection of open and short defects in PCB connectors and IC bond wires without physical contact or powering the DUT, reducing waste and improving testing efficiency while being cost-effective and scalable.
Implementation Method 1
In response to the stimulus signal, capacitive couplings are generated between the signal line and the ground line, between the signal line and the first conductor, between the ground line and the second conductor, and between the first and second conductors, collectively providing effective capacitances corresponding to the signal lines, respectively.
Implementation Method 2
A resonance frequency for each of the signal lines is determined based on the inductance and the effective capacitances, respectively.
Data Source
AI summary
A sensor device is provided for detecting electrical defects in a device under test (DUT). The sensor device includes a signal line configured to conduct a stimulus signal through a first conductor in the DUT; an inductor connected in series with the signal line for providing an inductance; and a ground line arranged adjacent to the signal line and configured to provide a ground path through a second conductor in the DUT for the stimulus signal conducted through the signal line and the first conductor. A resonance frequency for the signal line is determined based on the inductance and an effective capacitance of the signal line generated in response to the stimulus signal. An increase in the resonance frequency indicates an open defect in the first conductor and/or the second conductor, and a decrease in the resonance frequency indicates a short defect between the first conductor and the second conductor.