Traditional continuity test methods only do a basic pass/fail test that may miss critical defects. 4-wire Kelvin test is the best method for ensuring that circuit connections are optimal. Kelvin tests detect defects such as via and hole wall conductivity issues, trace line imperfections that cause high resistance, and surface contaminations that cause contact issues.
Why 4-Wire Kelvin Test
The traditional method for testing PCB circuit resistance is to test for continuity at a set resistance value (10 ohms for IPC Performance Class 3). This means a circuit that should have a very low resistance of 0.1 ohms can have a resistance value of up to 10 ohms and still pass a test. This defective circuit will likely cause performance and reliability issues.
Kelvin test can detect high resistance continuity failures and ensure circuit integrity. A report of a circuit’s resistance values can be generated, which may be useful for design and manufacturing of critical high-end products, and confirming the integrity of the PCB prior to assembly.
Our Kelvin Test Capabilities
- Range: 0.25mΩ - 1kΩ
- Accuracy: +/- 0.025 mΩ +/- 2%
- Contact Pressure: 0.2 g to 5.0 g
- Min test pad size: 4 mil
4-Wire Kelvin Test Explained
Kelvin Test, also known as 4 terminal sensing, is a method for making resistance measurements very accurately. It can be used to measure very low resistance. Each of the two test points has two probes, one force probe and one sense probe. The force probe applies a constant current, while the sense probe measures the voltage. A very accurate resistance reading is derived from the sense probe’s measurement.