Tip Style Materials - BeCu vs. Steel

QA Technology tip styles are manufactured from beryllium copper and steel. They are heat treated for durability and plated with hard gold to eliminate surface oxides and to lower electrical resistance. We offer a wide range of standard point styles to cover a variety of testing applications.

Diagram A compares the electrical performance of 100-25 series probes with beryllium copper and steel plungers with gold plating. There is a slight but measurable difference in the average resistance between the two base materials. The steel plungers average 5 or 6 milliohms higher resistance than the equivalent tip styles made of BeCu. Note that the bulk electrical resistance of BeCu is .08 microO- meters at 20°C, while the steel in QA tip styles are .18 microO- meters. Although steel has about twice the bulk resistance of BeCu, the difference it makes in probe resistance will not affect the vast majority of test applications. The hardness of steel plungers typically ranges between 58 and 60 on the Rockwell C scale, versus 38-42 for beryllium copper. Steel tip styles will, therefore, remain sharp longer than BeCu plungers.

chart showing average electrical resistance of beryllium copper and steel plungers with gold plating

In cases of heavy side loading over many cycles, testing shows virtually no difference in wear between BeCu and steel tip styles. Sixteen pieces each of 100-PRP2524S and 100-PRP2524S-S were run for 500,000 cycles at two-thirds travel against a contact surface angled 30º from horizontal. There was no difference in life between BeCu and steel, see Diagram A and Table A.

Electrical Resistance (milliohms) Summary for 30° Side Load over 500,000 Cycles
  Base Material Min. Max. Avg. Std Dev
  BeCu 7 16 11 1.22
  Steel 10 24 15 2.35