Two-Wire Kelvin Contact Resistance Measurement for Accurate DUT Testing
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Solution Overview
Problem
The contact resistances (CRES) at the points where wires of a two-wire Kelvin connection make contact with a Device Under Test (DUT) can affect the accuracy of electrical measurements, particularly when testing low-resistance components, and there is a need for determining these resistances accurately.
Innovation Solution
A method and apparatus for determining the first and second CRES by performing specific voltage and current measurements with each measurement path of the two-wire Kelvin connection coupled and decoupled to the DUT, using a predefined measurement current and high-ohmic voltmeter, allowing for individual determination of each CRES without additional resources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If contact resistances are not measured and compensated, then measurement process is simple and fast, but measurement accuracy deteriorates due to parasitic resistances affecting low-resistance component measurements
Solution Approach 1:
The measurement process is segmented into distinct phases: a first measurement phase where both measurement paths are coupled to the DUT to obtain a first measurement value, and second/third measurement phases where only one measurement path is coupled at a time to obtain second and third measurement values. This segmentation allows separate characterization of contact resistances and DUT resistance, resolving the contradiction by making the complex measurement process systematic and manageable while achieving high accuracy.
Solution Approach 2:
The contact resistances are determined in advance through preliminary measurement actions before the final DUT resistance measurement. By performing measurements with only one measurement path coupled at a time, the contact resistances are characterized beforehand, allowing their effects to be compensated in the final calculation. This preliminary action eliminates the harmful effect of contact resistances on measurement accuracy.
2Measurement precision
If additional measurement paths and resources are used to determine contact resistances, then measurement accuracy improves, but device complexity and resource requirements increase
Solution Approach 1:
The existing measurement apparatus is made multi-functional by utilizing the same measurement paths and components for different measurement purposes. The first measurement path serves both as a force path (supplying current) and a sense path (measuring voltage) at different times. The second measurement path similarly serves dual functions. This universality allows contact resistance determination without adding dedicated measurement resources, resolving the contradiction between accuracy improvement and device complexity.
Solution Approach 2:
The measurement apparatus performs self-characterization by using its own components to measure and determine its internal contact resistances. The system measures the contact resistances of its own measurement paths without requiring external test equipment or additional resources. This self-service capability enables accurate contact resistance compensation while avoiding the need for additional measurement apparatus.
3Measurement precision
If contact resistances are determined through separate measurements, then measurement accuracy improves, but measurement time increases
Solution Approach 1:
The measurement process maintains continuity by seamlessly transitioning between different measurement configurations. The apparatus continuously performs measurements - first with both paths coupled, then with only one path coupled at a time - without interrupting the overall measurement flow. The control unit coordinates these continuous measurements to determine contact resistances and DUT resistance in an integrated process, minimizing idle time and maintaining measurement momentum throughout.
Solution Approach 2:
The measurement process employs periodic switching between different measurement configurations. The system alternates between measuring with both measurement paths coupled and measuring with only one measurement path coupled, using periodic action to systematically gather the necessary data for contact resistance determination. This periodic switching enables accurate measurements to be taken in a structured, time-efficient sequence.
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 more accurate Kelvin measurements by compensating for parasitic resistances, preventing overvoltage damage, and monitoring contact quality, while increasing test parallelism and reducing test time in high-volume production.
Implementation Method 1
The contact resistances (CRESs) at the points where wires of a two-wire Kelvin connection make contact with a Device Under Test (DUT) can affect the accuracy of electrical measurements
Implementation Method 2
supplying a predefined measurement current to the DUT via the first measurement path and measuring a first voltage at an input node of internal circuitry of the DUT
Data Source
AI summary
In accordance with an embodiment, a method for determining a first contact resistance or a second contact resistance that includes: performing a first measurement using both a first measurement path and a second measurement path coupled to a device under test (DUT) by supplying a predefined measurement current to the DUT via the first measurement path, and measuring a first voltage at an input node of internal circuitry of the DUT to which the first and second measurement paths are coupled; and performing at least one of: a second measurement using only the first measurement path coupled to the DUT for determining the first contact resistance, or a third measurement using only the second measurement path coupled to the DUT for determining the second contact resistance.