Case study

Background of the Problem What happened ? A spring broke suddenly and the probe became useless.
Measurement Conditions
  • Electric Current - 10A Probe - CP40-A SPS (Spear, Spring Force 285g)
  • Probe - Wire connected to a receptacle by soldering (See, Methods of Wiring)


The utmost cause was that the temperature was raised at the contact point due to the high contact resistance. The high temperature melted the plating material on the DUT, which was led to fusing to the probe. The way to solve this problem is to decrease contact resistance as much as possible.

See the detail


Changing the wire connection method can solve this problem

Change the wiring method
Wiring to a receptacle(=indirect wiring to a probe) ⇒ Wiring to a probe (by soldering or with a terminal)
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The wire needs to be connected to the probe itself. This wiring method can fix the main path of current-flow into the probe body.
The large amount of current, to the degree that is far beyond the capacity of the probe, can sometimes flow unexpectedly. In that case, the current can flow through the spring even if wire was connected to the probe. It can cause the spring fusing.