USEFUL INFORMATION

The INGUN Part Number
The logical constellation of the INGUN Part No. allows clear identification and recognition of the Test Probes. The individual numbers define the Series, Material, Tip-Style and Diameter, Spring Force and Assembly Conditions (i.e. grid etc.). Within the series, the various combination possibilities are described on each data sheet.

After choosing the individual components, the Order No. of the Test Probe can be derived using the following system:

1  Type of Product 
·   E = E-Type Probe
· GKS = GKS Standard Test Probe
· HFS = HFS High-frequency Probe
· HSS = HSS High-current Probe
· HMS = HMS Stroke-measuring Probe
· PKS = PKS Pneumatic Probe
· SKS = SKS Switching Probe
·  KS = KS Receptacle
 
2  Series  
 
3  Tip Material  
0 = Delrin
1 = Brass
2 = Steel
3 = CuBe
 
 
4  Tip Style   (see overview)
 
5  Tip Diameter 
in mm/100 (e.g. 090 = 0.9mm) 
 
6  Tip Plating  
A = Gold
G = Aurun
N = Nickel
R = Rhodium
 
 
7  Spring Force 
in N ( Newton )/10 (e.g. 20 = 2.0N) 
 
8  Collar Height 
Collar Height of the Barrel in mm
00 = no Collar
 
 
9    Special Designation
(e.g. “C” = heat-proof)

 

Ingun North America

Wobble and Minimum Test Pad Size

Due to the necessary play between the Plunger and the Barrel of a Test Probe, the tip can be deflected out of the ideal (i.e. vertical) position. This deflection, the so-called “wobble”, was measured on INGUN Test Probes using a state-of-the-art optical measuring machine. This machine can, on request, also be used to verify customized Test Fixtures. To define the minimum test point size, the various tolerances of the Test Fixture were also taken into consideration.

Basically, the statement can be made that no direct dependency between the wobble and the contacting accuracy of a Test Probe exists. Important is especially the position of the probe tip at the time of actual contacting. For the subsequent stroke it is even often an advantage when a greater wobble exists, because this then helps to reduce the wear when the plunger is pressed down into the barrel. Furthermore, the tendency to bend the Test Probe is reduced and thus the life-expectancy prolonged. The minimum test point size is stated for all common Test Probes and is related to the usage in INGUN Test Fixtures.

The following diagram shows the deflection of the Plunger from the ideal position (i.e. the centre of the assembly hole) of various Test Probes. The experimental set-up was made with a standard INGUN probe plate, and the Test Probes were inserted in Receptacles. The row of experimental tests was carried out a number of times. Between each measurement the Test Probes were activated a few times.

The result of the investigation offers no information about other factors, which must also be taken into consideration, i.e. the tolerances of the PC-Board and of the Test Fixture assembly as well as the uncertainty and faults, which can be incurred during insertion and removal of Receptacles and Test Probes. Therefore, INGUN recommends the usage of a guide plate (especially in the case of critical applications, i.e. Test Point Size < 0,8 mm) with which the plunger tips are guided. Then, the majority of the tolerances can be ignored.

Base Materials

The choice of the base materials is dependent on the demands put on each individual component.

Brass is sometimes used for passive tip-styles and for machined barrels. The high percentage of copper makes it an ideal electrical conductor. Brass, however, is too soft for aggressive tip-styles.
Steel is used for practically all aggressive tip-styles. It provides a high level of hardness and sharpness of the points and the flanks. This ensures good durability and reliable contacting.
BeCu (Beryllium-Copper) provides a good combination and compromise between brass and steel: The high percentage of copper makes it an ideal electrical conductor and the small percentage of Beryllium allows the base material to be hardened (up to 435 HV). This then ensures good durability and optimizes the aggressiveness of the plunger tip.
New-Silver (NiAg) and Bronze are mainly used for Receptacles and the Barrels of the Test Probes. These materials have a high tensile strength, which is ideal for the long-term life of Test Probes. Furthermore, these materials provide a good elasticity of the crimps on the Receptacles.

Spring Steel of the highest possible quality is used for the manufacturing of the springs. For high and low temperature ranges, certain high-alloyed spring steels (i.e. stainless steel) are used.

Plating Materials

Hard-gold, chem. Nickel and Rhodium are used. The choice of plating materials is made according to functional features.

Hard-gold: best chemical resistance, Hardness 150-200 HV. Especially good against oxidation.
Aurun: this gold-alloy plating type was developed especially for Test Probes and has a very good chem. resistance. Hardness 300-350 HV. Usage for aggressive tip-styles for testing unwashed PC-Boards.
Rhodium: extremely good resistance to wear, Hardness 600-1000 HV; very brittle. Usage when special demands in regard to durability of the plunger tip are required. Because of the brittleness, this plating material is not suitable for aggressive tip-styles in conjunction with high spring forces.
Chem. Nickel: very good chem. resistance, Hardness 400-600 HV. Important because of the true depositing, i.e. without build up on points and edges (so-called “dog-bone” effect). Very suitable as durable layer for plungers. Because of the relatively high ductility. This plating material is ideal for aggressive tip-styles.

All plating materials guarantee the best contacting reliability due to the very low specific resistance values of 4-8µ.