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X Probe Logo X39-25 Series | 0.039 [1.00] Centers | 0.250 [6.35] Full Stroke

Designed for loaded board testing.


39mil 250 Stroke Socketless Probe for loaded board testing

Spring Force

spring force chart

Probe Selection

QA Technology offers many combinations of probes. You can build your probe by selecting the tube style, tip style and spring force for your specific application.

If you have questions at any time during the process, contact us at (603) 926-0348.

P/N X39-PR P25
NOTE: Not all combinations are available. Please verify your part number to be sure it is valid.
If you need assistance, please call 603-926-0348.

Begin building your part number.

NOTE: P has already been selected for you as the default tube material.
      Current Rating1
Letter Material Average Resistance MW @ 120°C SS @ 204°C
 P Nickel silver/ID precious metal clad < 25 milliohms 3.4 Amps 4.7 Amps
Select your tip style. Standard material is heat-treated BeCu/plated gold over nickel.
Choose Steel for steel plungers, if available.
Use the drop-down menu at right to filter your choices by target type.
Select your spring force.
Letter Spring Force Preload @ 0.167 [4.24]
Material Cycle Life @
0.167 [4.24] Stroke
 L Low 1.2 [34g/0.33N] 3.0 [85g/0.83N] MW 1,000,000
 S Standard 1.1 [31g/0.31N] 4.3 [122g/1.20N] MW 1,000,000
 H High 2.4 [68g/0.67N] 5.6 [159g/1.56N] MW 1,000,000
 Y Elevated 3.2 [91g/0.89N] 8.0 [227g/2.22N] SS 25,000
 E High Preload (Available only
with headless -S tip styles)
4.2 [119g/1.17N] 8.0 [227g/2.22N] SS 10,000
Select your option (if required).
Letter Description
 N No probe lubrication. Removing probe lubrication greatly reduces cycle life and should only be used in applications requiring operating temperatures below -55°C.
Steel Heat treated steel/plated gold over nickel. (see tip styles for availability).
You may add your Part Number to your Order.

1Current Rating is affected by spring material and lubrication choice. MW springs and lubrication both have a 120°C operating temperature limit. Use SS springs with no lubrication (-N) for testing up to 204°C. Before using probes near these limits, please refer to Current Carrying Capacity and Operating Temperature Application Notes.

2Maximum plunger OD should be used to calculate minimum guide plate clearance holes.

All specifications subject to change without notice. All dimensions are in [mm]. All spring forces are oz [gm/newtons]. US Patent No. 6,570,399 & 4,885,533