ProductsSingle-Ended Probes
The Structure of Single-Ended Probes
Contact probes—also known as pogo pins, probe pins, or spring-loaded pins—are essential components used in a wide range of electrical continuity and circuit board inspections among other applications. Each probe consists of three main parts: the plunger, barrel (pipe), and spring.
Plunger: Contacts directly the target electrode, applying the appropriate force through its stroke motion.
Barrel: Houses the internal spring and guides the plunger’s motion, ensuring mechanical stability.
Spring: Adjusts the contact force (spring load), enabling reliable and consistent electrical connections.
As the plunger moves within the spring-loaded barrel, it maintains stable contact with the target electrode—making precise and repeatable electrical testing possible.
Types of Single-Ended Probes
Probe Materials and Characteristics
The materials listed below are standard examples. We can propose custom materials tailored to your inspection requirements.
| Parts / Process | Material | Characteristics |
|---|---|---|
| Plunger | Beryllium copper (BeCu) | Commonly used for its low electrical resistance. With a hardness around HV-400, it may wear quickly when used on hard surfaces. It is non-magnetic. |
| Free-cutting carbon tool steel (SK) | Also widely used, offering higher hardness (approx. HV-600) and better durability—ideal for needle and crown-type tips. It is magnetic. |
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| Lead-free SK | Conventional cutting materials often contain small amounts of lead. This lead-free variant offers improved machinability while eliminating lead content. |
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| Metal alloys (S2 or S5) | Alloys of silver, palladium, and copper, offering hardness of HV-400–500, long life, and low resistance. Plating is not required, and it’s resistant to solder transfer. It is non-magnetic. |
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| Barrel | Phosphor bronze (PB) | An alloy of tin and phosphorus, commonly used for general-purpose applications. It is non-magnetic. |
| Brass (Bs) | Used for thicker probes; an alloy containing zinc. It is non-magnetic. |
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| Nickel Silver (NS) | A copper-based alloy with nickel, resistant to discoloration and corrosion without plating. Used in SQ catalog series only. |
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| Spring | Piano wire (SWP) | Standard spring material with heat resistance up to approx. 120°C. Spring load can be customized. |
| Stainless steel (SUS) | Withstands higher temperatures (up to 200°C) and provides superior heat and corrosion resistance. Offers slightly lower spring load. |
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| NAS | High-performance material suitable for temperatures up to 270°C. Also ideal for non-magnetic applications. |
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| Seiken Original Non-Magnetic Spring |
Completely non-magnetic and compatible with ultra-fine pitch probes (as small as 150μm pitch). |
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| Plating | Nickel (Ni) | Electroless nickel is commonly used as a base layer. It is magnetic. |
| Gold (Au) | Standard plating offering low resistance and stable performance (HV-150 to 200). |
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| Palladium (Pd) | Harder than gold with a hardness around HV-500. |
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| Others | We also offer even harder options like rhodium (Rh), depending on your inspection conditions. |
Probe Tip Shapes and Applications (Examples)
We offer various standard tip shapes and can also propose custom solutions based on your testing requirements.
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Round (S〇-1 Series) Ideal for FPCs and cases where electrodes must not be damaged. |
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Needle (S〇-2 Series) Suitable for precise inspections of PCB pads. |
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Flat / Reverse Cone Used for tests requiring even contact surfaces. Flat tips prevent electrode damage; reverse cones are effective for terminal sockets. |
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Triangular Pyramid (S〇-4 Series) Ensures secure contact—used for through-hole testing. |
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Crown (S〇-5 Series) Provides stable multi-point contact—great for BGA, ball terminals, and component leads. |
We offer a variety of probe tip shapes to match your specific application. Contact us for tailored recommendations.
Selecting Spring Load / Force
Each probe series offers various spring load options.
Choosing the Right Probe – e.g., from the SE Series
If you need a round tip with high force, we recommend the SE-1V(ED).
How to Make the Most of Your Single-Ended Probes
Contact probes are inserted into sockets, which are fixed into resin holders. Only the worn-out probes need to be replaced, making maintenance simple and reducing long-term operating costs.
- Note: Handling ultra-fine probes requires advanced technical skill.
- Detailed usage guidelines are available on a separate page.
Get the Single-Ended Probes You Need
For orders over 50 pieces or for custom requests, please contact us through the inquiry page.
Small Lot Orders
Previously, a minimum order of 50 units was required. Now, you can purchase catalog products starting from a single piece via MiSUMi-VONA (Not all of our catalog probe are included). Perfect for one-off testing or trial use.
Fixture Manufacturing
One-Stop Support for Inspection Fixtures
At Seiken, we provide more than just contact probes. We offer end-to-end solutions, including material machining, socket integration, and wiring. We also accept orders for machining alone.
Please feel free to reach out to us with any questions or requests.