Custom Semiconductor Probe Pins Machined to the Micron
We manufacture pogo pin plungers, barrels, cantilever probe needles, and test socket contact pins entirely to your drawing — on Swiss-type CNC machines that handle bar stock from Ø0.5 mm, holding ±0.005 mm tolerance and Ra ≤ 0.2 µm bore finish.
Probe Pins: The Contact Interface of Semiconductor Testing
A semiconductor probe pin is a precision-machined contact component that creates a temporary, repeatable electrical connection between test equipment and a device under test (DUT) — whether that's a bare wafer, a packaged IC, a PCB, or an electronic subassembly.
The pin is the most critical consumable in the test chain. Its dimensional accuracy directly determines contact resistance, signal integrity, cycle life, and test yield. A barrel bore that's 5 µm out of round causes plunger binding. A plunger OD that's 8 µm oversized causes seizure after a few hundred cycles. A tip radius 10 µm off nominal changes contact force enough to produce inconsistent electrical results.
We don't sell catalog pins. We machine your design — your geometry, your material, your plating specification — on Swiss-type CNC equipment from CITIZEN and Tsugami that was built specifically for small-diameter, high-precision turned components.
Pin Types We Produce
Pogo Pin Plunger
The dynamic contact element of a spring-loaded assembly. OD held to ±0.005 mm for controlled radial clearance inside the barrel bore. Tip geometry — crown, dome, flat, chisel, pointed — machined per your drawing.
Pogo Pin Barrel
The housing that guides the plunger and contains the compression spring. ID bore finish and roundness are the governing specs — Ra ≤ 0.2 µm and roundness ≤ 0.002 mm to minimize friction and contact resistance variation.
Cantilever Probe Needle
Used in wafer probe cards and PCB test fixtures. Long, slender needle profiles machined on Swiss-type sliding headstock — the only platform that eliminates deflection on L/D ratios above 5:1 without chatter or taper.
Test Socket Contact Pin
Precision-turned contacts for IC test sockets and burn-in sockets. We supply machined subcomponents to your socket designer's BOM, or complete assemblies to your drawing. Full lot traceability standard.
Pogo Pin Anatomy — Cross Section
Every Part of the Pin, to Your Spec
A pogo pin has three precision-machined components. We manufacture all three — as individual component supply, or as a complete kit to your BOM. Each component has its own machining challenge that our Swiss-type equipment is designed to solve.
Component 01
Plunger
The plunger is the dynamic interface — it contacts the DUT pad and transmits the electrical signal. Its OD must be held to tight tolerance relative to the barrel bore to achieve controlled radial clearance without binding or excessive play.
Tip geometry defines the application: crown tips penetrate oxide layers, chisel tips scrub contamination, flat tips minimize pad damage in fine-pitch wafer test, pointed tips self-align on PCB vias.
Component 02
Barrel
The barrel is the structural housing. Its bore guides the plunger and contains the spring. Bore ID, roundness, and surface finish are the most demanding features we machine — a degraded bore finish manifests directly as increased and variable contact resistance.
We use precision boring tools on CITIZEN machines to achieve Ra ≤ 0.2 µm bore finish at diameters down to Ø0.8 mm, verified by Mitutoyo surface roughness instrument on every production lot.
Component 03
Cantilever Probe Needle
Cantilever needles are used in wafer probe cards. They are long, slender, and demand extremely tight diameter control over the full length — the exact profile that Swiss-type sliding headstock machining is designed for.
The guide bushing in our CITIZEN machines supports bar stock within 0.5–2 mm of the cutting zone. No deflection, no taper, no chatter — even at L/D ratios that would be completely unmachinable on a conventional CNC lathe.
Why Swiss-Type Is the Right Machine for Probe Pins
Probe pin components are the archetype of Swiss-type work: small diameter, tight tolerance, high L/D ratio, high volume. Every aspect of our equipment lineup is pointed at this category.
Guide bushing eliminates deflection
The guide bushing holds bar stock within 0.5–2 mm of the cutting zone. A Ø1.0 mm plunger shaft produces zero chatter and zero taper — impossible on a conventional lathe at this diameter.
Live tooling completes complex geometry in one setup
Cross-holes, flats, grooves, and retention features are milled in the same cycle as turning. No secondary fixturing means no inter-operation dimensional accumulation error.
Sub-spindle finishes the back end without re-chucking
CITIZEN machines pick off the part in the sub-spindle and finish the solder-tail or press-fit end in the same program. Part accuracy is never compromised by a second chuck setup.
Bar stock from Ø0.5 mm — covers every pogo pin design
Our CITIZEN A16 machines handle Ø0.5 mm bar stock. That covers the finest probe pin plungers in current IC test socket designs — and most of what will be specified next generation.
Equipment Available for Probe Pin Production
Primary platforms highlighted. All have live tooling and sub-spindle.
| Machine | Type | Bar Range | Tol. | Units |
|---|---|---|---|---|
| CITIZENA16 | Swiss sliding headstock | Ø0.5–15mm | ±0.005 | 4 |
| CITIZENA20 | Swiss sliding headstock | Ø0.5–25mm | ±0.005 | 15 |
| CITIZENBNC 40 | Turn-mill fixed head | Ø5–120mm | ±0.005 | 4 |
| TSUGAMIB206 | Swiss-type CNC lathe | Ø1–20mm | ±0.005 | 20 |
| MAZAKTurn-Mill | Multi-axis turn-mill | Ø5–60mm | ±0.005 | 18 |
| NOMURA1085 | Swiss sliding headstock | Ø1–6mm | ±0.005 | 4 |
Highlighted rows are primary platforms for probe pin work.
The Numbers on Your Inspection Report
These are values our CMM reports confirm on production lots — not brochure claims. Every probe pin order ships with a dimensional inspection report traceable to ISO 10012-certified instruments.
Material Selection for Probe Pin Performance
Wrong material choice in a probe pin manifests quickly — as contact resistance drift, plunger seizure, or premature tip wear. We machine all standard probe pin materials and can advise on selection based on your duty cycle, operating temperature, and current requirements.
Beryllium Copper Recommended
Default choice for plungers and barrels requiring long cycle life, low contact resistance, and fatigue resistance. C17510 offers higher conductivity with moderate hardness for power test applications.
Free-Cutting Brass C360 / C385
High-volume barrel stock where cost matters more than maximum cycle life. PCB test fixtures, lower-duty-cycle production testers, and applications below 100K cycles.
Stainless Steel 303 / 316L
Spring elements and barrels where corrosion resistance or non-magnetic properties take priority over conductivity. Also used in cleanroom and wet chemical environments.
Phosphor Bronze C510 / C544
Preferred barrel material in high-frequency applications where barrel material affects signal integrity. Better elastic stability than brass, no beryllium handling concerns for assembly teams.
Plating Options
Plating is the active contact interface. We coordinate all plating through our certified partner network with full XRF verification and traceable lot documentation.
Hard Gold (Ni + Au)
Most common probe pin plating. Nickel subplate (2–5 µm) prevents diffusion; hard gold (0.3–3 µm) provides low contact resistance and oxidation immunity. 50K–1M+ cycles depending on thickness.
Palladium + Gold (Pd/Au)
Higher hardness than pure gold, excellent wear and oxidation resistance at elevated temperature. Standard in burn-in socket applications and high-cycle semiconductor ATE programs.
Electroless Nickel (EN)
Uniform coverage regardless of geometry. Used on barrel exteriors for corrosion resistance and solderability. EN alone is not suitable for contact surfaces — gold overplate required.
Rhodium (Rh)
Extreme hardness (800–900 HV). Used in very high-cycle wafer probe card applications exceeding 1 million insertions where standard gold wears prematurely. Higher cost, justified by extended service life.
Silver (Ag)
Highest conductivity of common contact platings. Used in power-test applications where current-carrying capacity is the governing requirement. Requires controlled-atmosphere storage.
Custom Plating Stack
Work to your specification. Any barrier / hardness / contact layer combination. Thickness verified by Seiko SII SEA1000A XRF analyzer. Cross-section analysis available on request.
Where Our Probe Pins Go to Work
Probe pins appear at every stage of semiconductor test — wafer-level, package-level, and board-level. Each stage has distinct requirements for geometry, material, and plating.
Wafer Probe Cards
Cantilever needles contacting bond pads on un-diced wafers for parametric and functional test. Fine pitch (≥120 µm pad pitch), force uniformity ≤±20%, and extreme straightness are the governing requirements.
IC Test Sockets (ATE)
Spring-loaded pogo pins in automated handlers for final test of packaged ICs — BGA, LGA, QFP, CSP. Low contact resistance, fine pitch, and 100K–1M+ cycle life are the critical parameters.
Burn-In Sockets
Elevated temperature stress testing at 125–150°C. BeCu material, Pd/Au plating, and consistent contact force across full temperature range are required. Cycle life targets: 500K+.
PCB In-Circuit Test (ICT)
Bed-of-nails fixtures testing populated boards. Spring-loaded contact pins compress onto test vias and pads. Spring force, pin pitch, travel range, and tip geometry are specified by your fixture designer.
Power Device Test
High-current probe contacts for IGBT, SiC MOSFET, and power module test. Larger plunger diameters (Ø2–6 mm), silver or thick-gold plating, and higher spring forces optimize current-carrying capacity.
Production & Functional Test
Charging contacts, programming interfaces, and product-specific test connections in high-volume manufacturing lines. We machine the exact geometry that integrates with your product's pad layout or charging interface.
Inspection Protocols for Probe Pin Production
Probe pins fail at the measurement limit — a few microns of dimensional error in the plunger-to-barrel clearance directly changes contact resistance. Inspection isn't a final gate for us; it's a continuous feedback loop at every machining station.
Every production lot ships with a dimensional inspection report. For automotive or aerospace programs, we issue full first article inspection (PPAP Level 3 or AS9100D FAI) before production approval.
IATF 16949:2016
FMEA, PPAP, control plans, SPC. Applies to automotive probe pin programs including EV charging contacts and sensor connector pins.
AS9100D — Aerospace QMS
First article inspection, configuration control, and lot traceability for aerospace test socket and structural probe components.
ISO 10012:2003 — Measurement Management
Every gauge used in probe pin inspection operates under a documented, traceable calibration system. No unverified measurements reach the inspection report.
Inspection Equipment for Probe Pin Verification
Documents Shipped With Every Order
What Makes Us the Right Manufacturer
We Go to Ø0.5 mm — Most Don't
Our CITIZEN A16 handles bar stock from Ø0.5 mm. At that diameter, Swiss-type sliding headstock is the only machining approach that works. We have 4 dedicated units, with 15 more A20 units covering up to Ø25 mm.
Bore Finish Verified Every Lot
Barrel bore quality determines plunger friction — which determines contact resistance variation across your test population. We check Ra on every production lot with a Mitutoyo roughness meter, not just at first article.
We Machine Components, Not Catalog SKUs
We machine your drawing. That means your tip radius, your retention groove, your thread, your press-fit diameter — exactly as designed. No forced compromise to fit a standard geometry we happen to stock.
Volume Capacity Without Delivery Risk
With 54+ Swiss-type and turn-mill machines, we run multiple programs concurrently. A tight delivery on one customer's order doesn't displace yours. Lead time is confirmed at quoting and held to.
Plating in Our Network — One Document Set
We coordinate gold, EN, Pd/Au, and rhodium plating through our certified partner network. One PO, one lot number, one document package. You don't manage a separate plating vendor or second traceability chain.
Semiconductor Industry Track Record
We already machine semiconductor valve bodies, VCR fittings, EP process components, and IC assembly hardware for clients in the US, Korea, and Japan. Probe pins are a natural extension of that work, not an unfamiliar category.
From Drawing to Qualified Probe Pin
Probe pins have no tolerance for ambiguity. Our process is designed to surface specification gaps early — before machining — and document every decision so there's no misalignment at delivery.
Drawing Review & DFM Assessment
We review your 2D drawing and 3D STEP file, verify tolerances against our process capability, and flag any features approaching the process limit — wall thickness, bore-to-OD concentricity, minimum tip radius — before we quote.
Common DFM findings: barrel wall below 0.15 mm, bore-to-OD concentricity tighter than ±0.003 mm, tip radii below R0.05 mm. We document all findings before quoting — no surprises at first article.
Quoting — 24 to 48 Hours
Detailed quote covering material, machining cycle, plating, inspection, and packaging. Unit pricing at your required volume, with alternative quantity tiers shown if they affect lead time or cost meaningfully.
Process Planning & Tooling
Machine selection, boring tool specification, fixturing design, and QC control plan documented before the first piece is cut. For probe pins, we specify the boring bar type, cutting parameters, and Ra verification interval at this stage.
First Article with Full Dimensional Report
We machine a first article lot (typically 5–20 pcs), perform full dimensional inspection against your drawing, and issue an inspection report. Parts are held until you approve. No production starts on unapproved first articles.
FAI report covers all drawing dimensions with actual values, surface finish readings, material cert reference, and operator sign-off. Available in FAI (AS9100D) or PPAP Level 3 (IATF 16949) format.
Production with In-Process QC
Full production with IPQC inspection at defined intervals. CCD auto-sorters perform 100% OD verification on plunger diameters. Bore finish checked at setup and at regular intervals throughout the run.
Final Inspection, Plating, and Shipment
OQC inspection before plating handoff. Post-plating XRF plating thickness verification on request. Complete document package assembled and shipped with every order.
Questions We Hear from Test Engineers
What file format do you need for a probe pin quote?
A 2D drawing in PDF or DXF with all critical dimensions and GD&T callouts is the minimum. A 3D STEP file is strongly preferred for complex tip geometries — it eliminates interpretation errors on tip radius, chamfer angle, and feature transitions. If you only have a sample pin you want reverse-engineered, send it — we can measure and generate a drawing from the physical part.
Can you match a competitor's catalog pin dimensions exactly?
Yes — provide us with a drawing or a sample we can measure, and we can machine to those dimensions in your material choice. We regularly produce drop-in replacements for standard catalog pins, often with a material upgrade or tip geometry the original supplier doesn't offer. We need a legitimate engineering basis (your drawing or a measured sample) — we won't reverse-engineer a proprietary design without that.
How tight a bore tolerance can you hold on a Ø1 mm barrel ID?
At Ø1 mm bore, our standard is +0.005/0.000 mm with bore roundness ≤ 0.002 mm. Tighter tolerances (±0.002 mm) are achievable on specific bore diameters with dedicated setup — confirmed during DFM review and documented in the control plan. Bore finish (Ra ≤ 0.2 µm) is held regardless of bore size, verified on every lot by Mitutoyo roughness meter.
What is your minimum order quantity?
No fixed minimum. Prototype and first article runs of 5–50 pcs are common for new socket designs in development. Volume production typically ranges from 5,000 to 500,000+ pcs per order. Unit pricing scales with volume — your quote shows pricing at multiple quantity tiers so you can plan your inventory and call-off strategy.
Do you supply complete pogo pin assemblies (plunger + barrel + spring)?
We specialize in machining the plunger and barrel. Spring procurement and final assembly can be coordinated — discuss during DFM review and we'll confirm scope. Many customers prefer to receive machined components and assemble in-house; others want complete assemblies. We work to your preference and document the scope explicitly in the purchase order.
Can you machine beryllium copper safely? Any special handling needed?
Yes — BeCu (C17200, C17510) is one of our most common probe pin materials and our machines are set up to handle it safely. BeCu machining generates beryllium-containing dust, managed through enclosed machining environments and proper filtration — an established part of our standard process. Finished machined BeCu parts are safe to handle without special precautions; the hazard is specific to machining dust, not the solid alloy.
What's the typical lead time for first article and production?
First article: typically 10–15 working days for standard geometries, 15–25 for complex tip profiles or unusual materials. Production after first article approval: 15–35 working days depending on quantity and scheduling. We provide a confirmed lead time at the quoting stage — it's a KPI we hold ourselves to, not just a number we print.
Can you verify plating thickness on finished pins?
Yes. Our Seiko SII SEA1000A X-ray fluorescence (XRF) analyzer provides non-destructive plating layer thickness and composition measurement — gold over nickel, palladium over nickel, and other stacks. XRF reports can be included in your shipment documentation on request. For applications requiring cross-section verification, we arrange destructive analysis at an external lab with results documented in the lot record.
Ready to discuss your probe pin requirements?
Submit your drawing and we’ll review tolerances, confirm feasibility, and return a quote within 24–48 hours. No commitment at the quoting stage.
- Quote within 24–48 hours
- DFM feedback included at no charge
- Ø0.5 mm minimum bar diameter
- ±0.005 mm standard tolerance
- Au, Pd/Au, Rh plating available
- IATF 16949 & AS9100D certified