Cycle Life

Kelvin Life Cycle Test

The 4-Wire Kelvin Life Cycle Test is an important step in the design evaluation process. IDI has developed a new generation of programmable Life Cycle Test Systems capable of delivering fast and accurate feedback to our design engineers. Each test system is capable of determining the reliability and performance characteristics of our probes. This ensures that the electrical and mechanical performance of each probe meets engineering specifications, as well as customers' expectations. Each system was designed with an open architecture, allowing for the flexibility necessary to adapt to the growing needs of the ATE industry.

Typical Test Set-up

1. Up to 64 spring contact probes are installed into receptacles that have been press fitted into a matrix of holes drilled into a G-10 fiberglass block.
2. The G-10 block is mounted firmly to a stage with the contact probes perpendicular to the test platen. The platen used is made of copper, plated with .005 inches of silver, and 50 micro-inches of gold to contact the probe tips.
3. The test platen is mounted to a precision cross roller slide driven by a cam and micro-stepper motor. At set-up, the mechanical stroke of the probe can be controlled with great precision.
4. Test cables are soldered to each receptacle and plugged into multiplexers that route the signals to the digital multi-meter and current source.
5. The program, written with LabVIEW™ Version 5.1, controls all aspects of the test such as current settings, stepper motor speeds, mechanical stops for resistance, stroke loss and pauses.
6. The software also features on-screen SPC analysis, which is available at any point during the test.

Physical Parameters

1. Resistance is measured using the 4-wire Kelvin test. This method uses apair of wires to supply constant current to the device under test (DUT). A separate pair of wires measures the voltage drop across the DUT. This method allows the system to void the resistance of the measuring leads. The resistance of the test platen is then offset with software. The system is calibrated at regular intervals with standards traceable to the National Institute of Standards Technology. The system has proven accuracy to within +\- .5 milliohms. The 5 ½ digit multimeter is directly connected to the PCI slot of the computer and acts as the data acquisition card as well.This allows information to be digitized and transferred directly across the 100 MHz bus of the computer without cables.
2. The current source provides constant current to the DUT. The output current
is verified before the DMM triggers the multiplexer and is corrected programmatically if needed. This provides repeatable measurements over time and eliminates current drift. The current is adjustable from .010 to 1 amps with a maximum compliance voltage of 125 volts DC.

3. The cycle rate is set at 4 Hertz for most tests, but can be adjusted from 1 to 12 Hertz programmatically.
4. The LabVIEW™ software used to program the test system gives the flexibility needed to meet the changing demands of the ATE industry. The open architecture allows changes to be made quickly to adapt to our customers’ needs.