Probe tubes are deep drawn from a variety of alloys and clad
materials. In the drawing process, precision flat stock is
formed into tubes through a sequence of progressive dies.
Standard nickel silver alloy and custom designed clad
materials are used in tube manufacturing process. Deep drawing gold
clad stock (with the gold on the inside diameter) hardens
the precious metal layer, producing tubes with a uniform layer
of gold on the inside surface. This is a critical surface,
for it makes sliding contact with the probe plunger.
QA is an industry leader in the use of gold clad materials
for probe construction. The various probe tube materials offered
by QA give the needed options for testing in any environment.
How to Select the Proper Tube Material
Probe tubes may be clad, plated, or left unfinished, depending
on the intended application. The following is a summary of
the various options and their applications:
"N" Style Probe Tube: This nickel silver
tube with no cladding or plating is suitable for most
bare board test applications where probe resistance
below one ohm is acceptable, or when cost is an issue.
Oxides which form on the inside surface of the tube
can impede current flow between the tube and plunger.
"G" Style Probe Tube: The same as the "N"
tube, but with a layer of gold plating on the outside
surface of the tube. On .100 [2.54] and .075 [1.91] center spacing probes,
the plating also covers the inside of the probe tube
and improves performance considerably compared to the
"P" Style Probe Tube: The "P" tube
is deep-drawn from nickel silver alloy with precision metal clad on the inside surface, and is used for in-circuit testing
where low and consistent electrical resistance is necessary.
The deep-drawing process hardens the gold, improving
wear characteristics and resulting in a gold layer of
extremely uniform thickness along the entire inside
surface of the tube.
"H" Style Probe Tube: The "H" tube
is made from a proprietary, high conductivity alloy, gold plated.
These tubes are used in high current applications, very
humid environments or where extremely low electrical
resistance is required.