Most pogo pin selection errors are not made at the plating stage or at the force stage. They are made at the
first step, before either of those is decided. This guide gives the order that works, and explains why the
order cannot be rearranged.
Why the sequence decides the outcome
A pogo pin is a spring loaded contact. Its electrical performance is a consequence of its mechanical state: how far the spring is compressed, and how much normal force reaches the contact point. Everything else — plating, current capacity, cycle life — is downstream of those two variables.
Stroke first
Working stroke determines where on the spring you will actually be operating. Get this wrong and every later choice is made against the wrong operating point.
Force second
Force is selected against the stroke you will really run, not against the nominal stroke on the datasheet.
Plating last
Plating is chosen against how much wear the contact point will see, which is a function of stroke position and force.
The common failure sequence runs in the opposite direction: plating is chosen first because it appears in the part number, force is chosen second from a catalogue table, and only then is working stroke checked. By that point the spring is already operating outside its intended range, and the plating and force figures no longer describe the part that will actually be built.
After stroke, force and plating are fixed, three checks remain: current and temperature rise, cycle life, and the termination and substitution grade that tie the contact into the rest of the assembly.
Stroke: nominal, working, and over-travel
Three different travel numbers get used interchangeably in conversation, and confusing them is the single most common source of pogo pin field failures.
| Term | What it means | Consequence of getting it wrong | Design rule |
|---|---|---|---|
| Nominal stroke | The spring contact’s rated full deflection, measured at the published reference position | Treated as a working position, it leaves no pre-load reserve | Never use as the operating position |
| Working range | The band of deflection in which the contact holds its specified force and resistance | Operating above the band: force rises and wear accelerates. Below the band: resistance is unstable | Operate in the middle of the band, not at its edge |
| Over-travel margin | The remaining deflection beyond the working position, available to absorb assembly tolerance | No margin: the contact bottoms out on a worst-case stack-up and force spikes | Reserve margin for board thickness, solder height and mating-side tolerance |
| Contact point position | Where the plunger actually meets the mating surface at the working position | Mis-set position moves the wear zone and changes resistance | Locate by measurement, not by assumption |
Working position, not nominal stroke, is the number that belongs in your mechanical design.
Stroke cannot be selected in isolation from dimensional tolerance. The position height of the contact, the true position of the contact point and the accumulated pitch error all move the effective working position, and they are covered in the Tolerance Control Guide. Selecting stroke without a closed stack-up means selecting against a position the assembly may never reach.
Spring force: the balance that sets contact resistance
Force is not a quality ranking. More force is not better. It is a balance point between contact resistance and wear, and it is specific to the application.
| Force band | Typical applications | Why this band | Main risk if misapplied |
|---|---|---|---|
| Light / low force — under 50 g | Wearable devices, light battery contacts, assemblies sensitive to compression space | Low pre-load suits thin assemblies and soft mating surfaces | Insufficient normal force: unstable contact resistance and micro-motion corrosion |
| Standard force — 60 g to 120 g | Standard board-to-board connection, docking and charging bases | Stable resistance at moderate cycle counts with acceptable wear | Chosen by habit rather than by measuring the mating surface |
| High force — 150 g and above | High-current transfer, high-vibration environments, test probes | Higher normal force resists separation and lowers contact resistance | Accelerated plating wear and higher insertion force on the assembly |
Give or take the exact figures in this table, the underlying rule matters more than the numbers: a force figure is only meaningful when it is measured at a stated stroke, with a stated mating pin, after a stated number of cycles. A force quoted without those three conditions cannot be compared against a competitor’s figure, and it cannot be verified on a first article.
Two consequences follow. First, ask for the measurement stroke whenever a force figure is quoted, including our own. Second, terminate the selection knowing that force is a function of the mating pin as well as of the contact, so the force you specify applies to a pair, not to a part.
Plating: chosen last, because it depends on the first two
Plating is the most visible line in a part number and the last decision that should be made. Wear at the contact point is a product of stroke position and force, so plating can only be selected once both are known.
| Plating | Thickness basis | Where it suits | Trade-off |
|---|---|---|---|
| Gold (Au) over nickel | Au 1–30 µ″ selectable, Ni underlayer 50–100 µ″ | Low and stable contact resistance; the usual choice for signal and mixed-signal contacts | Cost scales with the gold thickness required by the cycle count |
| Nickel (Ni) | Usually 50–100 µ″ as an underlayer | Barrier layer beneath gold; not intended as a final contact surface | Oxidises as a contact face; resistance rises over time |
| Palladium-cobalt (PdCo) | Selected against cycle count | High cycle-count and wear-resistant applications | Contact resistance and cost both need to be evaluated against the target |
Plating is an outsourced step for us, and we describe it that way. We do not operate a plating line. What we control is the specification and the verification: gold thickness selectable 1–30 µ″ over a nickel underlayer of 50–100 µ″, thickness measured on incoming lots rather than accepted from a supplier certificate, appearance and adhesion criteria applied at incoming inspection, and batch traceability retained so a plating deviation can be traced to a specific lot.
Plating thickness also belongs in the tolerance conversation, because build-up moves the contact point when measured at the contact face. See the Tolerance Control Guide for how plating contributes to the stack-up.
Current and temperature rise: check before you commit
A current rating without its test conditions is not a specification. Before committing to a contact, establish what the four controlling factors are in your design, and ask for the test report rather than the headline number.
| Controlling factor | Why it changes the answer | What we can provide | What we need from you |
|---|---|---|---|
| Mating pin design | Contact area and heat path depend on the pin geometry that meets our contact | Test reports on request | Counterpart drawing or pin specification |
| Housing / insulator | Thermal mass and airflow around the contact set the steady-state temperature | Test reports on request | Housing material and wall thickness |
| PCB copper | Copper area and layer count determine how quickly heat leaves the pad | DFM comment | Copper geometry around the pad |
| Ambient and duty cycle | Continuous and intermittent current load reach different steady states | Test reports on request | Ambient temperature and duty cycle |
Subject to specific mating pin and housing design. Test reports available upon request.
Our published position on current-carrying capacity.
In practice, the design lever that matters most is contact count. Where a single contact is marginal against the target current, splitting the load across additional contacts reduces current per contact and lowers local heating, which is usually cheaper than specifying a larger contact.
Cycle life: two things change, not one
Cycle life is commonly quoted as a single number. In service, two characteristics move together: contact resistance rises and normal force falls. Both need to be tracked, because a contact can still meet its resistance limit while its force has already fallen below the pre-load the design assumed.
| Item | Basis |
|---|---|
| Test conditions | Standard laboratory conditions (25 °C, 50 % RH), with specific mating surfaces |
| Tracked characteristics | Contact resistance, normal (spring) force, and visible wear at the contact point |
| Acceptance | Test stops when either characteristic leaves its limit; the cycle count at that point is reported |
| Reporting | Test reports available on request, with the mating surface used |
| What changes the result | Mating surface finish, contamination, ambient conditions and actual working stroke |
Tested under standard laboratory conditions (25 °C, 50 % RH) with specific mating surfaces. Life cycle varies by application.
Our published position on cycle life.
Where a design calls for a high cycle count, the usual answer is not a longer-life contact but a corrected working position: a spring operated near the middle of its band holds its force far longer than one already compressed close to its limit.
Termination and substitution grade
A pogo pin is rarely a part on its own. It is the first link in a chain — battery contact to harness to board — and the grade of substitution you accept determines how much of that chain has to be re-qualified.
Termination types we provide
| Termination | Used for | Note |
|---|---|---|
| SMT / SMD (surface mount) | Automated pick-and-place assembly | Suits high-volume board assembly |
| THM (through-hole) | Wave-soldered joints requiring high mechanical strength | Preferred where the joint carries withdrawal load |
| Solder cup / wire | Hand-soldered cable attachment | Suits low-volume and repair-friendly builds |
| Custom cable harness | Turnkey assemblies: contact overmoulded and crimped into a finished harness | Delivered as a complete assembly rather than a component |
Substitution grades
| Grade | What changes on your side | What we deliver |
|---|---|---|
| Drop-in | No design change | 2D Footprint Specs and first-article report |
| Pin-to-pin | Pin definition matches; footprint detail may need adjustment | 2D Footprint Specs, footprint confirmation, samples |
| Footprint-compatible | Footprint matches; electrical or force parameters re-verified | Parameter re-verification and test report |
| Custom | New design against your drawing | DFM review, tooling, first-article report, volume ramp |
Where a substitution crosses more than one link of the chain — a battery contact and the harness that serves it, for example — the grades have to be assessed together, because a drop-in contact feeding a re-qualified harness is not a drop-in assembly. Our cross-reference hub is organised around exactly that problem.
Common selection mistakes
Each of these leads to the same outcome: a contact that measured correctly in isolation and behaves differently in the assembly.
Using nominal stroke as the working position
Leaves no pre-load or over-travel reserve for assembly tolerance.
Quoting force without a measurement stroke
A force figure without its stroke and mating pin cannot be verified or compared.
Choosing plating from a catalogue
Plating is a function of cycle count and wear zone, not of part number.
Accepting a current rating without test conditions
The rating depends on the pin, the housing, the copper and the ambient.
Ignoring the mating-side tolerance
It is part of the stack-up even though it is not part of your purchase order.
Using an SMT part for a high-cycle application
Solder joints and pads see the withdrawal load too, not just the contact.
Forgetting PCB copper in the current path
Copper area and layer count decide how fast heat leaves the pad.
Opening tooling before the stack-up is closed
The most expensive order of operations there is.
Pogo pin selection questions engineers ask
What is the difference between nominal stroke and working stroke?
Nominal stroke is the rated full deflection published for the part. Working stroke is the band of deflection in which the contact holds its specified force and resistance. The operating position should sit inside the working band with margin left over — never at the nominal limit.
How do I know which spring force band my design needs?
Start from the assembly rather than from the contact. Thin assemblies with soft mating surfaces generally suit lighter force, while high-current and high-vibration applications need more normal force to stay stable. Then confirm the choice with a force measurement at the actual working stroke.
Which plating should I specify for a high cycle count?
Specify plating against the wear the contact point will see, which depends on stroke position and force. Gold thickness from 1 to 30 µ″ over a 50–100 µ″ nickel underlayer covers most signal applications, and palladium-cobalt is worth evaluating where cycle counts are high. Plating is chosen after stroke and force, not before.
Can you give me a current rating for this contact?
We publish it with its conditions instead of as a bare number: subject to specific mating pin and housing design, with test reports available on request. Send the mating pin, the housing and your ambient condition and we will reply against your configuration.
Do you provide 3D models?
We provide 2D Footprint Specs — application-matched dimensional data, verified against the drawing datum. Verified 3D data is available offline for specific programmes rather than as a public download, because an unverified model can hide stack-up on the mating side.
Can you take over a whole chain, not just the contact?
Yes. Custom cable harness assemblies are delivered turnkey, with the contact overmoulded and crimped into a finished harness where that is the practical route. For multi-part substitutions we assess the grades together, because a drop-in contact feeding a re-qualified harness is not a drop-in assembly.
How fast can I get a selection response?
Send the drawing, the mating-side geometry and the assembly method, and you receive a DFM review and a selection response within 12 hours.
Send your drawing. Get a selection response in 12 hours.
Working stroke, force band and plating confirmed against your mating geometry — not against a catalogue table.
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