Kelvin Force-Sense Contacts for Microcircuit Testing
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Solution Overview
Problem
Current microcircuit test equipment faces challenges in making accurate, low-resistance, and non-destructive electrical connections due to the small size and close spacing of microcircuit contacts, leading to incorrect identifications of defective devices and wear-related contamination issues, which increase costs and reduce throughput.
Innovation Solution
The development of a test system using electrically conductive force and sense contacts that form temporary mechanical and electrical connections with microcircuits, where force contacts deliver current and sense contacts measure voltage without drawing significant current, with designs that include forked or rod-shaped sense contacts to maintain alignment and prevent lateral wobbling, and sliding or hinged configurations to accommodate variations in terminal height and planarity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional test contacts are used to test microcircuits at high throughput, then productivity is improved, but wear and debris generation increase causing false defect identifications
Solution Approach 1:
The contact system is divided into separate force contacts and sense contacts. Force contacts apply mechanical pressure and deliver current, while sense contacts measure voltage without drawing significant current. This segmentation allows the sense contacts to detect actual device defects without being contaminated by wear debris from the force contacts, resolving the contradiction between high throughput testing and contact accuracy.
Solution Approach 2:
The sense contacts act as intermediaries between the force contacts and the microcircuit terminals. By using sense contacts to measure voltage drops across the device under test, the system can identify actual defects without the sense contacts themselves being contaminated by wear debris from the force contacts, maintaining reliability during high-volume production.
2Reliability
If force contacts are used to deliver current to microcircuit terminals, then electrical connection is achieved, but wear and debris are generated contaminating the test equipment
Solution Approach 1:
The contact system separates the current-delivery function (force contacts) from the measurement function (sense contacts). Force contacts are designed to withstand wear and generate debris, while sense contacts remain clean and uncontaminated because they only measure voltage without carrying significant current. This functional segmentation resolves the contradiction between achieving reliable electrical connection and minimizing harmful wear debris.
Solution Approach 2:
The measurement function is extracted from the current-delivery function. Sense contacts are dedicated solely to voltage measurement with minimal current draw, separating this function from the force contacts that handle current delivery and wear. This extraction ensures that the measurement function remains clean and accurate despite the presence of wear debris in the current-delivery path.
3Manufacturing precision
If sense contacts are positioned close to force contacts to maintain alignment, then manufacturing precision is improved, but lateral misalignment occurs causing incorrect connections
Solution Approach 1:
The sense contacts are positioned asymmetrically relative to the force contacts, with the sense contact array offset laterally from the force contact array. This asymmetric arrangement, combined with the forked geometry of the sense contacts, ensures that even if the overall contact assembly experiences lateral misalignment during manufacturing or assembly, the sense contacts will still make correct connections to the appropriate terminals, resolving the contradiction between manufacturing precision and connection accuracy.
Solution Approach 2:
The sense contacts incorporate forked or curved geometries that allow them to self-align and accommodate lateral misalignments. The forked structure enables the sense contact to engage with terminals even when the force contact array experiences lateral displacement, maintaining connection accuracy while allowing for manufacturing tolerances and assembly variations.
4Manufacturing precision
If multiple contacts are made to closely spaced terminals, then manufacturing precision is improved, but small errors in contact positioning result in incorrect connections
Solution Approach 1:
The sense contacts are positioned asymmetrically relative to the force contacts, with the sense contact array offset laterally from the force contact array. This asymmetric arrangement, combined with the forked geometry of the sense contacts, ensures that even if the overall contact assembly experiences lateral misalignment during manufacturing or assembly, the sense contacts will still make correct connections to the appropriate terminals, resolving the contradiction between manufacturing precision and connection accuracy.
Solution Approach 2:
The sense contacts incorporate forked or curved geometries that allow them to self-align and accommodate lateral misalignments. The forked structure enables the sense contact to engage with terminals even when the force contact array experiences lateral displacement, maintaining connection accuracy while allowing for manufacturing tolerances and assembly variations.
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 solution enables accurate and efficient testing of microcircuits by minimizing wear and debris-related issues, reducing false defect identifications, and extending the lifespan of test equipment components, thereby improving manufacturing efficiency and reducing costs.
Implementation Method 1
force contacts extending through longitudinal holes in the housing toward the device under test and being compressible/deflectable through the holes in the housing
Implementation Method 2
sense contacts measure voltage without drawing significant current
Implementation Method 3
a hinged portion connecting the fixed portion and the free portion
Implementation Method 4
The free portion includes a forked portion at its distal end that extends on opposite sides of a distal end of the corresponding force contact
Data Source
AI summary
Terminals (2, 502) of a device under test (DUT) are connected to corresponding contact pads or leads by a series of electrically conductive contacts. Each terminal testing connects with both a “force” contact and a “sense” contact. In one embodiment, the sense contact (770) partially or completely laterally surrounds the force contact (700). In order to increase the contact surface, the force contact, in a spring pin (700) configuration contacts the device under test terminal at that portion of the lead which is curved or angled, rather than orthogonal to the pin.