Bond Wire Latent Defect Detection via Capacitive Coupling
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Solution Overview
Problem
Conventional testing methods for integrated circuit (IC) devices fail to detect latent defects in bond wires, which can lead to device failure over time due to issues like near-shorts, especially in high-vibration environments, and existing methods like X-ray radiographs are expensive and prone to human error.
Innovation Solution
A method using capacitive coupling measurements between bond wires to identify latent defects by measuring fringing capacitance, which is inversely proportional to the distance between wires, allowing for the detection of near-shorts before they develop into hard shorts or opens, using a test system that applies a stimulus signal and measures the response to determine if the capacitance is within a predetermined range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional testing methods are used to test IC devices, then hard shorts and hard opens can be identified, but latent defects in bond wires cannot be detected
Solution Approach 1:
The patent performs capacitance measurements on bond wires during the manufacturing process, before the device is put into service. By measuring the capacitance values and comparing them against expected ranges, the system identifies latent defects (such as near-shorts) in advance, allowing defective devices to be filtered out before they can fail in the field.
Solution Approach 2:
The patent replaces physical inspection methods (such as X-ray radiographs) with electrical capacitance measurements. Instead of using expensive and complex imaging equipment, the system uses standard semiconductor test equipment to measure capacitance values, which are then used to infer the physical condition and spacing of bond wires.
2Measurement precision
If X-ray radiographs are used to detect latent defects, then defect identification is possible, but the cost increases and human error is introduced
Solution Approach 1:
The patent uses inexpensive, readily available semiconductor test equipment to perform capacitance measurements, replacing expensive X-ray radiography systems. The test equipment uses standard electrical signals and measurement circuits that are already present in semiconductor testing infrastructure, eliminating the need for costly specialized imaging equipment.
Solution Approach 2:
The patent enables the test equipment to automatically measure capacitance values, compare them against pre-established expected ranges, and identify defective devices without requiring human interpretation. The system self-automates the defect detection process, eliminating manual analysis and reducing human error.
3Reliability
If capacitance measurements are performed on all pin pairs, then latent defects can be identified, but testing time increases
Solution Approach 1:
The patent performs capacitance measurements on all pin pairs, which may seem excessive, but this comprehensive approach ensures that no potential latent defects are missed. By measuring every possible pair, the system guarantees complete coverage of all bond wire interactions, ensuring high reliability in defect identification.
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 approach allows for the early identification of latent defects in IC devices, reducing the risk of failure and is faster and less expensive than conventional methods, providing reliable predictions of device reliability through accurate capacitance measurements.
Implementation Method 1
measuring a response to the stimulus signal. The response indicates capacitive coupling between a bond wire attached to a first pin of the plurality of pins and a bond wire attached to a second pin of the plurality of pins
Implementation Method 2
measuring a fringing capacitance between a bond wire attached to first pin of the pair and a bond wire attached to a second pin of the pair; and determining whether the fringing capacitance is within a predetermined range
Data Source
AI summary
Disclosed herein are testing apparatus and methods to identify latent defects in IC devices based on capacitive coupling between bond wires. Bond wires may have latent defects that do not appear as hard shorts or hard opens at the time of testing, but may pose a high risk of developing into hard shorts or hard opens over time. A latent defect may form when two adjacent bond wires are disturbed to become close to each other. According to some embodiments, capacitive coupling between a pair of pins may be used to provide an indication of a near-short latent defect between bond wires connected to the pair of pins.