Case study

Background of the Problem The material of a Device Under Test (DUT) fuses to a probe as it contacts.
Measurement Conditions
  • Electric Current - 50A DUT - Aluminum plating
  • Probe - CP90-D4<8> SPS (carbon tool steel, serrated 52-point, 520g of 2/3 spring compression)


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.

This is a typical case to be brought to us very frequently.
A solution for it can be found in"selecting probes for high current" on this website. The following methods can help to decrease contact resistance under high current;


Strengthen the spring force - This problem can be caused by lack of spring force.
(eg. 2/3 spring compression 520g → 2000g)
Use conductive material for the tip
(eg. Carbon tool steel → silver alloy)
Increase probe tip points - More contact points can disperse the electric charge.
(eg. 52-point → 81-point)

<NOTE>When you increase tip points of the probe, the spring force can be dispersed at the same time, so that the “solution 1” can be ineffective in some applications. We recommend to measure contact resistance in advance and to know the most suitable spring force.