The primary current path in a spring loaded contact or probe is through the junction of the plunger with the barrel and the barrel with the receptacle, if a receptacle is used for quick-change capability. Secondary paths include the contact junction between the spring and plunger and the spring and barrel.
Resistance is dependent on several factors:
1. the conductivity of base metals and plating material,
2. the resistance at points of contact between components (which is affected by surface condition),
3. the area of contact,
4. the force applied at contact junctions,
5. The materials used,
6. and finally, the architecture and/or design.
For applications requiring very low, and consistent resistance, such as low voltage semiconductor testing it is possible to employ higher spring forces, or an enhanced bias design, that helps to maintains electrical contact between the plunger(s) and barrel of the product.
Resistance can be affected by other components in the integration of a spring loaded. Other components include:
1. surface contamination of the item being contacted
2. spring force used
3. the receptacle and/or wire terminations
4. wiring or cabling.
5. test interface design, and high-resistance contacts in the test system
6. tip selection
7. and more…
Spring contacts are typically designed to operate at a specified working travel. Some designs may be able to reach, and work at full travel position, but most have a sweet spot of operation around 2/3 compression.
Spring compression dynamics, and the overall design will dictate he maximum travel, and force that a spring loaded contact is able to attain.
You will find specifications, including force at a recommended travel, and other values provided by our Sellers throughout this site. We also provide a Spec Converter on the product pages, and in the footer of the home page to aid in converting between Imperial, Metric, and other values.
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