Pogo Pins for PCB Test Fixtures: Selection Guide & Specs

A pogo pin is a spring-loaded electrical contact probe used in bed-of-nails test fixtures to connect a circuit board's test points to external instrumentation. Each pin contains a plunger (the tip that contacts the board), a barrel, and an internal spring that maintains consistent contact force through thousands of test cycles. Pogo pins are also called spring-loaded test probes, spring contacts, or contact pins.

Selecting the right pogo pin means matching tip style, spring force, current rating, and pitch to your board's test points. Get those four parameters right and your fixture makes reliable contact every cycle. Get them wrong and you'll spend hours debugging intermittent failures that look like board defects.

How pogo pins work in bed-of-nails test fixtures#

In a bed-of-nails fixture, pogo pins mount into receptacles pressed or soldered into a probe plate. The probe plate is machined with holes positioned to match the test point locations on your PCBA. When an operator loads a board into the fixture and closes it, each pogo pin's plunger compresses against its target test point. The internal spring provides controlled contact force -- enough to push through surface oxidation and make solid electrical contact, but not so much that it damages the pad or component.

The plunger connects electrically through the barrel to the receptacle, which connects to the fixture's signal interface (hand-wired connections, TPCB, or feedthrough plate). From there, signals reach your test instrumentation: power supplies, DMMs, programmers, whatever the test plan requires.

This simultaneous contact is what makes bed-of-nails testing fast. Instead of manually probing one test point at a time, the fixture connects every point in the fraction of a second it takes the springs to compress. Drop board, press button, get results.

Spring mechanics and cycle life#

The spring inside each pogo pin determines two critical parameters: contact force and working travel.

Contact force is the pressure the plunger exerts on the test point when compressed to working height. Too little force and the probe skates across the pad surface without breaking through oxidation. Too much force and you risk damaging pads, lifting components, or flexing the board.

Working travel is how far the plunger compresses from its free position. Typical working travel is 1.5-2.5mm, which accommodates board warpage and thickness variation across the panel. If your boards have significant bow or twist, you need probes with enough travel to reach the lowest test points while the highest ones are already compressed.

A well-made pogo pin delivers consistent force across 500,000+ cycles. Spring fatigue is gradual -- you won't see a sudden failure. Instead, contact force drops slowly over time, eventually falling below the threshold needed for reliable contact. Track pass rates. If they decline without any change in the boards being tested, probe wear is the most likely cause.

Pogo pin tip styles for PCB test points#

The tip is the business end of the pogo pin -- the part that actually touches your board. Different test point geometries and surface conditions require different tip designs. Using the wrong tip creates intermittent contact failures that waste hours of debugging.

We carry four tip styles, each designed for specific test point types:

Crown tip#

Multi-point contact design with four or more small points arranged in a circle. The crown's geometry provides redundant contact -- if one point lands on oxidation or flux residue, the others still make connection. Crown tips are the workhorse choice for general-purpose test fixtures.

Use for: Solder-coated pads, through-hole test points, general-purpose functional testing. When in doubt, start here.

Watch out: Crown tips can scratch delicate gold finishes. The multiple contact points concentrate force on a small area, which is a feature on solder-coated surfaces (it breaks through contamination) but a problem on soft gold pads.

Serrated tip#

Aggressive contact surface with teeth that cut through flux residue, oxidation, and other surface contamination. The serrated design actively bites into the test point surface rather than relying on spring force alone.

Use for: Post-reflow boards with flux residue, oxidized surfaces, test points that have been handled or stored. Essential when boards come off the line without cleaning and go straight to test.

Watch out: Serrated tips will scratch and damage soft gold pads. They also wear faster than crown or flat tips because the teeth gradually dull. If your boards have gold finish test points, serrated tips will destroy them.

Flat tip#

Large, smooth contact area that distributes force evenly across the pad surface. The flat geometry avoids concentrating pressure on any single point, making it the gentlest option for sensitive surfaces.

Use for: Gold pads, ENIG finish, sensitive components where pad damage is unacceptable, and any application where surface finish preservation matters.

Watch out: Flat tips rely on the pad surface being clean. They lack the mechanical advantage that crown and serrated tips use to break through contamination. If your boards have flux residue or oxidation, flat tips will give you intermittent contact.

Concave tip#

Cup-shaped tip that self-centers on round features. The concave geometry captures cylindrical pins, component leads, and raised test points, holding them in the center of the contact area.

Use for: Round pins, headers, component leads, raised test points, through-hole connector pins. Any test point with a cylindrical profile.

Watch out: Concave tips make poor contact with flat pads. The cup shape results in edge-only contact on a flat surface, which is unreliable. Only use concave tips when the test point is genuinely round or raised.

Choosing the right tip style#

Match tip style to what your test points actually look like -- not what the BOM says. A pad specified as "gold finish" may arrive from the board house with flux residue from adjacent components, which changes the probe selection entirely.

Pogo pin specifications that affect test reliability#

Four specifications determine whether a probe works in your fixture. Get all four right and the fixture makes reliable contact. Miss one and you'll chase intermittent failures.

Spring force#

The force the plunger exerts on the test point when compressed to working height. Measured in grams-force (gf) or Newtons.

• 25-50 gf (light force): Delicate components, BGA interposers, flex circuits. Use when pad lift or component stress is a concern.
• 75-100 gf (standard force): General-purpose functional testing. Enough to break through light oxidation on solder-coated pads. This is the range for most fixtures.
• 150-200+ gf (high force): Heavy contamination, high-current contacts, applications requiring maximum contact reliability. Be aware that total probe force adds up -- 200 test points at 200gf requires 40kg of fixture closing force.

Total probe force matters for fixture design. Add up the spring force of every probe in the fixture to determine the actuation force your fixture mechanism must deliver. High-density fixtures with hundreds of probes may need vacuum or pneumatic actuation to provide sufficient closing force.

Current rating#

The maximum current a probe can carry continuously without overheating or degrading contact resistance.

• Standard probes (2-3A): Signal-level testing, logic signals, low-power measurements. Adequate for most functional test applications.
• High-current probes (9A+): Power rail testing, motor drive circuits, battery charging paths, LED driver testing. Use when the test plan requires sourcing or measuring significant current through specific test points.

Running a 5A power test through a 2A-rated probe won't cause immediate failure. It will gradually increase contact resistance, create measurement errors, and eventually damage the probe. If your test plan includes power testing, spec the current-carrying probes from the start.

Pitch (center-to-center spacing)#

The minimum distance between probe centers, determined by the barrel diameter plus clearance. Pitch constrains how closely you can place probes in the fixture.

Pitch determines the probe family (the mechanical series), which in turn determines compatible receptacles. You cannot mix probes from different pitch families in the same receptacle. When in doubt, choose the largest pitch your test point layout allows -- larger probes are more robust, carry more current, and cost less.

Travel#

The total distance the plunger can compress. Working travel (the recommended operating range) is typically 60-70% of total travel.

• 1.5-2.5mm working travel: Standard for most applications. Accommodates normal board warpage and thickness variation.
• 3mm+ working travel: For boards with significant bow, thick conformal coating, or applications where the fixture must accommodate multiple board thicknesses.

Insufficient travel means some probes won't reach their test points on warped boards. Excessive travel wastes spring force on compression rather than contact pressure. Match travel to your boards' actual flatness variation, not their specification.

What goes wrong: common probe selection mistakes#

We see the same mistakes repeatedly from teams building fixtures for the first time. These cost hours of debugging because intermittent contact failures look exactly like board defects until you figure out the fixture is the problem.

Defaulting to crown tip on gold pads. Crown tips are the safe general-purpose choice, but their multi-point design concentrates force on gold finishes, causing scratches and pad damage. After a few hundred cycles, the gold surface degrades enough to cause intermittent contact. Use flat tips on gold pads and ENIG finishes.

Ignoring spring force until contact failures at volume. Light-force probes work fine when you test five boards. After a few thousand cycles, plunger tips accumulate contamination and spring force drops slightly below the contact threshold. The fixture passes boards intermittently -- but only on a warm day when everything is just right. Start with standard force (75-100 gf) unless you have a specific reason to go lighter.

Mixing probe families in the same fixture. Different manufacturers use different barrel diameters, even at the same nominal pitch. A 100-mil probe from one vendor may not fit in a receptacle designed for another vendor's 100-mil series. Standardize on one probe family per fixture and match receptacles to that family.

Under-specifying current for power test points. Engineers select probes for signal testing (2-3A rating) and use the same probes for power rails carrying 5A+. The fixture works initially, but contact resistance rises over time, creating measurement errors that looks like a board calibration problem. Specify high-current probes for any test point that carries more than 2A.

Not accounting for total probe force. Each probe adds its spring force to the total closing force required. A 200-point fixture with 100gf probes needs 20kg of actuation force. If the fixture mechanism can't deliver that consistently, probes at the edges don't fully compress and you get position-dependent failures.

Two paths to tested boards#

Engineers land on this page for two reasons, and we support both:

Sourcing probes for a fixture you're building or maintaining#

We carry probes from Ingun, QA Technology, and other manufacturers -- the same components we source for our own fixture production. If you're building fixtures in-house or replacing worn probes in an existing fixture, you can buy components directly from our shop.

For detailed probe-to-test-point matching guidance -- including series compatibility, force calculations, and pitch constraints -- see the probe selection guide. And if you're also sourcing receptacles, our receptacles page covers the mounting hardware that holds probes in the probe plate.

Getting a complete fixture from FixturFab#

If you'd rather not source individual probes, match them to receptacles, drill probe plates, and wire everything up yourself -- we handle all of that. Upload your design files to Studio, configure online, and get instant pricing. Fixtures ship in 2-3 weeks. We select the right probes for your board's test points based on your Gerber files and test point file, so you don't have to become a probe expert.

About two-thirds of our fixture customers started by buying components for DIY builds before deciding it was worth letting us handle the fixture. If you're on your second or third revision and the debugging time is adding up, that's a common inflection point.

Probes we carry and use in our fixtures#

We stock probes from established manufacturers whose quality we verify through our own fixture production. When we build a fixture for a customer, it uses probes from this same inventory.

By pitch family#

By application#

Browse specific probe products and pricing on shop.fixturfab.com.

Probe lifecycle and when to replace#

Pogo pins are wear items. The spring, plunger tip, and barrel all degrade with use. How quickly depends on your test environment.

Expected cycle life#

Most quality probes from manufacturers like Ingun and QA Technology are rated for 500,000+ cycles under clean conditions. In practice, cycle life depends on:

• Board cleanliness. Flux residue and solder paste contamination accelerate tip wear. Boards tested immediately after reflow (no-clean process) wear probes faster than cleaned boards.
• Contact force. Higher spring force accelerates mechanical wear on both the probe tip and the test point surface.
• Tip style. Serrated tips wear fastest because the teeth gradually dull. Crown tips last longer. Flat tips last longest.
• Environmental conditions. Humidity and temperature fluctuations cause expansion and contraction that accelerate fatigue.

Signs it's time to replace probes#

• Rising contact resistance. Measure periodically with a milliohm meter. If resistance across a probe exceeds the manufacturer's specification, replace it.
• Declining pass rates. A gradual drop in pass rate with no change in the boards being tested usually means probe degradation.
• Visible tip wear. Crown tips with flattened points, serrated tips with dulled teeth. Inspect under magnification.
• Inconsistent test results. The same board passes some cycles and fails others. This is the hallmark of marginal contact.

Reordering#

When probes need replacing, you need the same part number from a compatible source. We carry the same probe families we install in FixturFab fixtures, so if you're maintaining a fixture we built -- or one you built with our components -- reordering from our shop means exact replacements without cross-referencing datasheets.

Pogo pin terminology: a quick reference#

The same component goes by different names depending on who's writing the datasheet. If you're comparing specs across manufacturers or reading fixture documentation, here's the translation:

"Pogo pin" originated as a brand name (from a manufacturer's product line) but is now used generically across the industry, similar to how "Band-Aid" became the common term for adhesive bandages. All the manufacturers we carry use the term interchangeably with "test probe" or "spring-loaded contact."

Frequently asked questions#

Q: What is a pogo pin?#

A pogo pin is a spring-loaded electrical contact probe used in test fixtures to make temporary connections to circuit boards. It has three parts: a plunger (tip) that contacts the test point, a barrel that provides structure, and an internal spring that maintains consistent contact force. Pogo pins are the standard contact technology in bed-of-nails test fixtures for PCBAs.

Q: How do I choose the right pogo pin tip style?#

Match the tip to your test point's geometry and surface condition. Crown tips work for general-purpose solder-coated pads. Serrated tips cut through flux residue and oxidation. Flat tips protect delicate gold or ENIG finishes. Concave tips self-center on round pins and headers. If you're building a fixture with mixed test point types, you'll likely use multiple tip styles in the same fixture.

Q: How many cycles do pogo pins last?#

Quality probes from manufacturers like Ingun and QA Technology are rated for 500,000+ cycles under clean conditions. Actual cycle life depends on board cleanliness, contact force, and tip style. Serrated tips wear fastest, flat tips last longest. Monitor contact resistance and pass rates to determine when replacement is needed -- gradual degradation is normal, sudden failures are not.

Q: What's the difference between a pogo pin and a receptacle?#

A pogo pin is the spring-loaded probe that contacts the board. A receptacle is the socket that holds the pogo pin in the fixture's probe plate and provides the electrical connection to the signal interface. They must be matched by series -- a probe from one manufacturer's 100-mil family won't necessarily fit a different manufacturer's 100-mil receptacle.

Q: Can I use pogo pins for high-current testing?#

Standard pogo pins handle 2-3A, which is sufficient for signal-level testing. For power rail testing, motor drive circuits, or LED driver testing, use high-current probes rated for 9A or more. These have larger barrels and heavier-gauge internal connections. Running excessive current through an undersized probe won't cause immediate failure, but contact resistance will increase over time, creating measurement errors.

Q: How do I select the right pogo pin pitch?#

Pitch is determined by the minimum center-to-center distance between your test points. Choose the largest pitch your layout allows -- larger probes are more robust, carry more current, and cost less. Common options: 0.635mm (25 mil) for high-density boards, 1.27mm (50 mil) for standard Dev and Dev Pro fixtures, and 2.54mm (100 mil) for production fixtures with wider test point spacing.

Source the probes or skip the sourcing entirely#

Browse pogo pins and other fixture components on our shop -- same parts we install in FixturFab fixtures. Or upload your design files to Studio and let us handle the probe selection, fixture design, and assembly. Fixtures ship in 2-3 weeks.