Kontaktimpedantsi

Kontaktimpedantsi (contact impedance) refers to the electrical resistance observed at the junction between two conductors when an electric current passes through. It is a crucial parameter in circuits and devices where tight, reliable connections are required, such as in printed circuit boards, power transmission, and medical implants.

The value of contact impedance is influenced by surface roughness, material composition, temperature, pressure applied across the interface, and the presence of oxides or contaminants. Even a small gap or oxide layer can increase impedance by several ohms, affecting signal integrity and power efficiency. In high‑frequency applications, impedance also includes capacitive effects, so contact impedance is often treated as a complex quantity measured in ohms or milliohms.

Measurement techniques for contact impedance involve placing a known test signal across the contact and sensing the resulting voltage or current. The simplest method is a four‑point probe, which eliminates lead resistance. For dynamic or in‑situ monitoring, impedance spectroscopy or time‑domain reflectometry may be employed. Accurate measurement demands stable temperature and mechanical conditions to prevent drift caused by thermal expansion or vibration.

High contact impedance can lead to overheating, signal distortion, or even complete circuit failure. Therefore, engineering practices such as ultrasonic cleaning, applying conductive greases, bump bonding, or increasing clamping force are commonly used to minimize it. In microelectronic test fixtures, designers often specify a maximum allowable contact impedance to ensure reliability across mass production.

In summary, kontaktimpedantsi is a fundamental electrical characteristic that bridges material science and circuit performance, requiring careful control and measurement to maintain efficient, reliable electronic systems.