C17200 beryllium copper foil is the definitive ultra-thin wrought copper alloy format for mission-critical applications requiring sub‑0.15 mm thickness without compromise on spring properties, electrical continuity, or fatigue endurance. As a precipitation‑hardened Cu‑Be alloy (UNS C17200 ± CuBe2 ± Alloy 25 ± DIN 2.1247 ± CW101C), this beryllium copper foil attains tensile strengths above 1380 MPa after age hardening—surpassing all other copper‑based materials—while preserving 22–28% IACS electrical conductivity, non‑magnetic behavior (permeability < 1.01), and corrosion resistance on par with pure copper, even in thin‑gauge configurations. Manufactured under ASTM B194, AMS 4533, and BS 3B 28 specifications via precision cold rolling followed by controlled atmosphere annealing, the foil format delivers thickness tolerances as tight as ±0.002 mm, flatness deviations ≤0.5 mm/m, and continuous coil lengths exceeding 35 feet without splices—directly applicable to high‑speed stamping of EMI finger gaskets, micro‑switch leaves, battery current collectors, and RF shielding layers. Unlike heavier strip products requiring secondary slitting or single‑part blanking, this beryllium copper foil is rolled to final width (1.0 mm–400 mm) with deburred or radius edges, eliminating downstream processing steps and reducing per‑part scrap. Available in tempers from dead‑soft annealed (A/TB00) for deep‑drawn diaphragms to mill‑hardened (AT/HT/TH01) for immediate high‑cycle spring function, the foil delivers stress relaxation retention > 90% after 1,000 hours at 150 °C, reverse‑bending fatigue endurance exceeding 10⁷ cycles at 40 ksi, and dimensional stability critical for miniaturized electromechanical systems in medical guidewires, MEMS packaging, and satellite deployment mechanisms. The following technical data sheet confirms conformance to global standards and provides engineering‑grade metrics for design validation, procurement qualification, and regulatory submission across aerospace, defense, medical, and commercial electronics supply chains.
Standards & Conformance
Beryllium copper foil is produced and certified to meet the following internationally recognized specifications, with full mill traceability and optional third‑party verification:
| Standard / Specification | Scope / Applicable Form | Key Requirements Covered |
|---|---|---|
| ASTM B194 | Copper‑beryllium alloy plate, sheet, strip, and rolled bar (includes foil thickness range) | Chemical composition limits, mechanical property ranges across tempers (A/AT/H/HT), dimensional tolerances for thin‑gauge products |
| ASTM B196 / B197 | Rod & bar / wire | Supplementary heat‑treat response validation; cross‑referenced for temper consistency |
| ASTM B251 | General requirements for wrought copper alloy strip | Edge finish classification, surface condition ratings, flatness and camber criteria |
| SAE J461 / J463 | Wrought and cast copper alloys | Unified numbering system (UNS C17200) property tables for aerospace procurement packages |
| AMS 4530 / 4533 | Sheet, strip, plate (aerospace grade) | High‑reliability temper (TH01/TF00) certification for flight‑critical foil‑formed components |
| BS 3B 28:2009 | British Standard for copper‑beryllium alloy strip and foil (solution treated and precipitation treated) | Specific foil tolerances, solution treatment protocols, precipitation hardening verification for UK aerospace and defense contracts |
| EN CW101C (CuBe2) | European wrought copper‑beryllium alloy standard | Chemistry equivalence (Be 1.8–2.0%), mechanical grade mapping (R430–R800), CE marking eligibility |
| DIN 2.1247 | German standard for CuBe2 beryllium copper | Wrought product specifications for precision engineering and automotive components |
| ISO 4137 | Wrought copper‑beryllium alloys | International harmonization of property ranges and test methods |
| JIS H3130 | Japanese Industrial Standard for beryllium copper sheets, plates, and strips | Thickness tolerances, temper designations, and inspection protocols for Asian electronics supply chains |
| RWMA Class 4 | Resistance Welding Manufacturer‘s Association classification | High‑strength designation (> 160 ksi tensile after aging) for foil used in welding electrodes and high‑cycle contact applications |
*Cross‑references: QQ‑C‑533 (historical federal specification), GOST 1789 (Russian strip/foil equivalent BrB2). Mill test certificates to EN 10204 Type 3.1 (standard batch) or Type 3.2 (with independent third‑party verification) are available upon request for all certified tempers and foil dimensions.*
Chemical Composition
The nominal chemical composition of beryllium copper foil per UNS C17200 (Alloy 25 / CuBe2 / DIN 2.1247) is presented below, compiled from ASTM B194 specifications, NGK Berylco production standards, and Materion (Brush Wellman) alloy data sheets:
| Element | Weight (%) | Specification Limits / Technical Notes |
|---|---|---|
| Copper (Cu) | Balance (≥ 97.5% min) | High‑purity copper matrix (99.5% Cu + alloying elements after trace adjustment); ensures baseline conductivity and corrosion resistance |
| Beryllium (Be) | 1.80 – 2.00 | Primary age‑hardening element; forms metastable gamma‑prime (γ′) and equilibrium gamma (γ) phase precipitates during heat treatment, generating the strengthening response attributable for > 200 ksi ultimate tensile strength |
| Cobalt (Co) | 0.20 min | Grain refiner; controls beryllide particle size and distribution during aging; enhances elevated‑temperature strength retention |
| Nickel (Ni) | ≤ 0.20 | Minor precipitation assist; when present with Co, improves aging kinetics and thermal relaxation resistance |
| Cobalt + Nickel (Co+Ni) | ≥ 0.20 (min) | Combined content governs age‑hardening response rate; lower limit ensures consistent property development across different coil positions |
| Cobalt + Nickel + Iron (Co+Ni+Fe) | ≤ 0.60 | Upper bound restricts excess intermetallic formation that reduces ductility and formability, particularly in the foil thickness range |
| Iron (Fe) | ≤ 0.10 | Tight control prevents embrittlement during cold rolling of thin‑gauge material; higher iron reduces fatigue life under cyclic loading |
| Silicon (Si) | ≤ 0.15 | Residual deoxidation element from primary melting; minimal effect on conductivity but monitored for welding compatibility |
| Aluminum (Al) | ≤ 0.10 | Trace impurity limit; elevated levels cause gamma‑phase instability during prolonged high‑temperature service |
| Lead (Pb) | ≤ 0.010 (0.02 max per AMS) | Ultra‑low lead composition (< 0.01%) ensures RoHS compliance for consumer electronics, medical devices, and European automotive contacts; verified by ICP‑OES per ASTM E1473 |
| Other Elements (Total) | ≤ 0.20 | Combined trace impurities from primary refining process are held to aerospace‑grade limits |
Note: Each coil is supplied with a certified mill test certificate (MTC) including ICP‑OES chemical verification per ASTM E1473. Composition applies uniformly across foil thickness range 0.0125 mm–0.4 mm with no gauge‑dependent variation.
Mechanical Properties (by Temper)
Mechanical performance of beryllium copper foil varies significantly with temper and post‑forming age‑hardening treatment. The values below consolidate data from NGK Berylco (Berylco 25), Materion (Alloy 25 Strip), MatWeb (UNS C17200 TH01 datasheet), Robert Laminage (CuBe2), eFunda, and AZoM materials databases:
| Temper / Condition | Temper Symbol | Tensile Strength (MPa / ksi) | Yield Strength (0.2% offset, MPa / ksi) | Elongation in 50 mm (%) | Hardness (Rockwell) | Typical Foil Application & Forming Requirement |
|---|---|---|---|---|---|---|
| Annealed (Solution Treated) | A / TB00 | 430 – 560 / 62 – 81 | 210 – 380 / 30 – 55 | 35 – 60 | B45 – 65 | Deep‑drawing of complex EMI finger profiles, intricate diaphragm geometries, and progressive die forming requiring maximum ductility |
| Quarter Hard | 1/4H / TD01 | 510 – 610 / 74 – 88 | 420 – 560 / 61 – 81 | 15 – 35 | B70 – 85 | Moderate bending operations for connector contact beams and relay leaf components where light cold work is retained |
| Half Hard | 1/2H / TD02 | 580 – 690 / 84 – 100 | 530 – 660 / 77 – 96 | 8 – 25 | B85 – 95 | High‑volume progressive die stamping for battery contact springs and SIM card connector terminals |
| Hard / Mill Hardened (Cold Rolled) | H / TD04 | 680 – 830 / 99 – 120 | 650 – 800 / 94 – 116 | 2 – 8 | B95 – C30 | Punching operations where no post‑blanking bending is required; typical for flat gasket fingers and EMI shielding frames |
| Mill‑Hardened (Aged, Formerly AT) | AT / TF00 | 1100 – 1400 / 160 – 203 | 1000 – 1200 / 145 – 174 | 4 – 10 | C36 – 40 | Precision springs, high‑cycle contact blades, and stamp‑and‑form components requiring immediate spring function without customer‑side heat treatment |
| Heat‑Treated (Peak Aged, Formerly HT) | HT / TH01 | 1205 – 1480 / 175 – 215 | 965 – 1380 / 140 – 200 | 2 – 6 (after aging) | C38 – 42 (up to C45 peak aged) | Aerospace connectors, sensor diaphragms, and other flight‑critical applications where maximum strength is required in the smallest cross‑section |
| Extra Hard (Peak Aged Mill State) | XHM / special | ≥ 1480 / ≥ 215 | ≥ 1300 / ≥ 188 | 1 – 3 | C40 – 46 | Bourdon tubing raw stock, bellows foil, and ultra‑thin measurement instrumentation requiring highest achievable modulus and creep resistance |
Key supplementary mechanical indicators for ultra‑thin foil formats:
| Property | Value | Condition / Reference |
|---|---|---|
| Fatigue Strength (10⁷ cycles, R=‑1 reverse bending) | 275 – 310 MPa / 40 – 45 ksi | Aged (HT/TH01) temper; values verified on 0.1 mm foil thickness samples |
| Elastic Modulus (tension) | 125 – 130 GPa (18.1 – 18.9 × 10³ ksi) | Applicable to all tempers; slight anisotropy (< 5% variation) in rolling direction versus transverse orientation |
| Shear Modulus (modulus of rigidity) | 50 GPa (7,250 ksi) | Isotropic value for torsion loading; critical for EMI finger stock performance under lateral deflection |
| Poisson‘s Ratio | 0.300 – 0.34 | Age‑hardened condition; ν = 0.300 nominal for design of diaphragms and pressure‑sensing elements |
| Formability Ratio (90° bend, good way — minimum radius/thickness) | 0 (can be bent flat on itself without cracking) | Annealed (A/TB00) temper at 0.025 mm–0.10 mm thickness; HT temper requires radius/thickness ≥ 2 for bend‑without‑failure |
| Stress Relaxation Resistance (% stress retained after 1,000 h) | > 96% @ 100 °C; ~92% @ 150 °C; ~85% @ 200 °C | Mill‑hardened condition; documented by Materion and NGK Berylco for Alloy 25 foil applications in elevated‑temperature automotive environments |
| Machinability Rating (UNS C36000 free‑cutting brass = 100%) | 20% (standard temper); up to 60–70% (C17300 lead‑bearing variant for automatic screw machining) | Foil‑to‑foil applications typically not machined; rating listed for design reference when converting from bar or rod forms |
| Electrical Contact Resistance (million – mΩ range) | < 5 mΩ (after tin/silver plating); 5–15 mΩ (unplated, freshly cleaned surface) | Measured at 10 mA, 0.1 N contact force; crucial for low‑power signal relay and sensor contact applications |
*Note: Mechanical property tables apply to products after age hardening (precipitation treatment). Solution‑annealed tempers (A/TB00) exhibit lower strength values prior to customer‑performed aging.*
Physical Properties
The following table summarizes the intrinsic physical parameters of beryllium copper foil (C17200 / Alloy 25 / CuBe2) in the age‑hardened state unless otherwise noted. Values are compiled from NGK Berylco, Materion, Robert Laminage, Goodfellow, AZoM, and ASM Aerospace Specification Metals (ASM) databases:
| Property | Metric Value | Imperial Value | Notes / Condition |
|---|---|---|---|
| Density (age hardened) | 8.25 – 8.36 g/cm³ | 0.298 – 0.302 lb/in³ | Increases approximately 4–6% vs. solution‑annealed state (8.25 → 8.36) due to gamma‑phase precipitation; density increase corresponds to ~2% maximum linear contraction during aging |
| Density (as solution annealed / A temper) | 8.25 g/cm³ | 0.298 lb/in³ | Applies to A‑temper foil prior to age hardening; verified by ASTM E‑specific gravity methods |
| Melting Range (liquidus — solidus) | 866 – 980 °C | 1590 – 1796 °F | Narrow melting range restricts brazing temperature selection; incipient melting avoided below 980 °C |
| Electrical Conductivity at 20 °C | 22 – 28% IACS (standard aged) | 12.8 – 16.2 MS/m | 22% IACS minimum for aged (HT/TH01) temper; annealed A‑temper foil (prior to age hardening) measures ~15–18% IACS; up to 30% IACS achievable in over‑aged conditions at modest strength reduction |
| Electrical Resistivity | 6.2 – 7.8 μΩ·cm | 37 – 47 Ω·cmil/ft | Reciprocal to conductivity range; temperature coefficient positive, linear up to 200 °C |
| Thermal Conductivity at 20 °C | 105 – 135 W/m·K | 60 – 78 BTU/(ft·hr·°F) | 105 W/m·K typical for peak‑aged (HT) foil; 135 W/m·K achieved in conductivity‑optimized processing routes (e.g., over‑aging) for thermal management applications |
| Coefficient of Thermal Expansion (CTE) | 16.7 – 17.8 × 10⁻⁶ / °C (20–200 °C range) | 9.3 – 9.9 × 10⁻⁶ / °F (68–572 °F) | Low hysteresis in thermal cycling (± 1.5 × 10⁻⁶ / °C difference between heating and cooling curves); critical for bellows and diaphragm pressure gauges |
| Specific Heat Capacity (cₚ) | 0.42 kJ/kg·K | 0.10 BTU/lb·°F | @ 20 °C, independent of temper and aging condition |
| Magnetic Permeability (relative, µᵣ) | < 1.01 (AMSolite = 1.0032 typical) | — | Non‑magnetic to less than 1% deviation from air (µ₀); no susceptibility even after extensive cold rolling or stamping; retains non‑magnetic property across full temper range (A through HT) |
| Electrical Resistivity Temperature Coefficient | 0.0015 – 0.0020 / °C (20–200 °C) | — | Positive, linear; enables resistance‑based temperature sensing in foil strain gauge applications |
| Emissivity (oxidized surface) | 0.55 – 0.70 (dependent on oxide thickness and surface finish) | — | Relevant for radiative cooling calculations in hermetically sealed electronic enclosures |
| Reflectivity (visible light, polished surface) | ~ 55–60% | — | Moderate reflectivity; often overplated with tin, silver, or nickel to enhance conductivity or solderability rather than reflectivity |
*Note: Electrical conductivity referenced to International Annealed Copper Standard, where IACS = 58 MS/m (100% conductivity) at 20 °C. Values for solution‑annealed foil (A/TB00 temper) are ~15‑18% IACS before age hardening; contact for temper‑specific certified values.*
Key Selling Points by Region
Our beryllium copper foil provides distinct value propositions for buyers across different global markets, based on regional manufacturing priorities, regulatory frameworks, and supply chain dynamics:
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South Asia & Southeast Asia (India, Vietnam, Thailand, Malaysia, Singapore, Philippines): Electronics manufacturing hubs drive demand for ultra‑thin beryllium copper foil in 0.025–0.15 mm thickness, mill‑hardened AT (TF00) temper, for SIM card contacts, battery leaf springs, micro‑switch blades, and mobile PCB shielding layers. Regional buyers prioritize unit economics through competitively coiled weights (20–300 kg per spool), JNPT port logistics (Mumbai), Singapore transshipment availability, and ASEAN tariff exemptions under ATIGA (ASEAN Trade in Goods Agreement). India‘s BIS certification for beryllium copper wire/strip is available upon request for government‑tendered electronics and defense contracts.
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Greater China (China, Taiwan, Hong Kong): The world’s largest consumer of precision beryllium copper foil for consumer electronics (smartphones, wearables, batteries) and industrial automation components. Chinese buyers require GB/T 5231 and YS/T 323‑2002 compliance alongside ASTM B194. Typical foil thickness 0.03–0.20 mm in coil widths 2–300 mm for high‑speed multi‑out progressive dies. Factory‑to‑factory shipments from bonded zones reduce import duty exposure.
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Japan & South Korea: Advanced electronics and automotive industries require beryllium copper foil meeting JIS H3130 (Japanese Industrial Standard) with exceptional surface finish (Ra ≤ 0.08 μm) and thickness uniformity (± 0.001 mm across 200 mm width). Korean buyers (Samsung, LG supply chain) specify IATF 16949 process certification and PPAP Level 3 documentation. Late‑model foil for EV battery contact systems and foldable display hinge springs.
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Middle East (UAE, Saudi Arabia, Kuwait, Qatar, Bahrain, Oman): Oil & gas and petrochemical safety applications require beryllium copper foil for non‑sparking tool components (heavy‑gauge foil converted to safety tool edges and striking surfaces), downhole MWD/LWD instrument housings (thin wall, high‑strength cladding), and pressure switch diaphragms for refinery instrumentation. Non‑magnetic (µᵣ < 1.01) and anti‑galling properties prevent spark ignition in explosive atmospheres—critical for ATEX and IECEx classified operations across GCC petrochemical plants. Saudi Arabia‘s SABER certification available upon pre‑shipment documentation.
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Europe (Germany, France, UK, Italy, Spain, Poland, Netherlands, Sweden): European engineering demands beryllium copper foil with full REACH (EC 1907/2006) and RoHS 2011/65/EU compliance for EV battery contact systems (800 V architectures), automotive sensor contacts, and high‑current relay components. German automotive tier‑1 suppliers require IATF 16949 process certification with PPAP Level 3 documentation. BS 3B 28:2009 certification specifically endorsed for UK aerospace and defense foil contracts. Sustainability declarations (carbon footprint per kg of CuBe2 foil, calculated under ISO 14067 methodology) available upon request.
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North America (USA, Canada, Mexico): Aerospace applications (AMS 4530 / AMS 4533) drive procurement of beryllium copper foil in non‑magnetic, high‑fatigue configurations for aircraft instrumentation housings, landing gear anti‑galling bushing wraps, and avionics connector shell feedstock. U.S. domestic end‑users require DFARS (Defense Federal Acquisition Regulation Supplement)‑compliant certified mill lots with full DOT‑classified hazardous material (beryllium) safety data sheets and conflict‑mineral declarations (EICC/GeSI). Canadian C.R.C. certification for aerospace material imports available.
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South America (Brazil, Argentina, Colombia, Chile): Brazilian electronics and automotive sectors emphasize local test certification (INMETRO registration) and Mercosur origin documentation for reduced intra‑bloc tariffs. Foil used in automotive electrical contact assemblies (connection systems for local vehicle manufacturers) and consumer electronics. Chile‘s mining sector requires beryllium copper foil for heavy‑equipment wear plates and non‑sparking pump shims, where abrasion resistance and corrosion resistance in acidic mine water (pH 2–4) are decisive factors. Colombia‘s electronics manufacturing free‑trade zones provide tariff exemptions for imported alloy foil meeting ASTM standards.
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Africa (Nigeria, South Africa, Angola, Morocco): Mining and mineral processing operations specify beryllium copper foil for heavy‑equipment wear plates and non‑sparking pump components, where abrasion and corrosion in acidic mine water (pH 2–4) are decisive. South African import controls require pre‑shipment inspection via SGS or Bureau Veritas for high‑strength precision alloy foil customs classification (HS 7409.1900). Nigeria‘s oil & gas sector uses beryllium copper foil as replacement stock for safety tool refurbishment programs.
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Australia & New Zealand: Defense and aerospace contracting through Australia‘s Defence Strategic Review framework requires beryllium copper foil with full supply chain traceability to NATO Codification Bureau (NSN assignment eligibility). Foil used in submarine sensor housings (non‑magnetic, high‑fatigue requirements) and marine propulsion monitoring diaphragms. New Zealand agricultural technology (automated milking systems) uses foil for precision sensor contacts in harsh, wash‑down environments.
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Global Maritime & Offshore: Seawater corrosion resistance comparable to nickel‑silver makes beryllium copper foil the preferred material for deep‑sea ROV connector housings, offshore platform electrical panel grounding strips, and subsea sensor diaphragms. Zero susceptibility to hydrogen embrittlement and hydrostatic pressure tolerance (to 4,000 m depth equivalent / 40 MPa external pressure) ensure long service life in underwater environments. Marine certifications (ABS, DNV, Lloyd‘s Register) available for qualified suppliers—contact for per‑order verification.
Primary Applications: How Engineers Use Our Foil
C17200 beryllium copper foil serves mission‑critical functions across the following industries and components. The table below cross‑references specific foil applications with governing standards, typical temper, and performance rationale:
| Industry / Sector | Specific Foil Application | Gauge Range / Temper | Why Beryllium Copper Foil? |
|---|---|---|---|
| EMI / RFI Shielding | Finger stock gaskets, contact strips, shielded door gaskets, board‑level shielding frames, automotive electronics compartment grounding fingers | 0.05–0.20 mm / mill‑hardened AT or HT | > 100 dB attenuation with low closure force (2–5 N/cm); continuous coil lengths up to 35 ft / 10.7 m without splices ensures uninterrupted stamping; high cycle resilience > 1 million compressions without set; tin, nickel, or silver plating available for corrosion protection and solder attachment |
| Micro‑Electronics & Consumer Devices | Smartphone SIM / smart card connector blades, battery contact springs, USB‑C and memory slot terminal leaves, micro‑switch spring leaves, MEMS packaging grounding clips | 0.025–0.15 mm / 1/2H or mill‑hardened AT | 22‑28% IACS conductivity combined with > 140 ksi yield strength permits narrow‑beam contact designs; low and stable contact resistance (< 5 mΩ after plating); non‑magnetic prevents signal interference in high‑frequency (5G / Wi‑Fi 6) communication paths; available in widths down to 1.0 mm slit‑to‑width |
| Medical Devices | Guidewire torque cores, endoscopic instrument actuator springs, micro‑surgical gripper flexures, implantable device connectors (encapsulated), hearing aid battery contacts | 0.0125–0.08 mm / mill‑hardened HT (sterilization‑compatible) | High fatigue endurance in minimally‑invasive instruments where deflection cycles exceed 10⁶; excellent biocompatibility for short‑term implantable contact housings; non‑magnetic compatible with MRI guidance systems; RoHS and REACH compliant for EU medical device regulation (MDR) applications |
| Aerospace & Flight Systems | Altimeter aneroid capsules, air data computer diaphragm pressure sensors, avionics connector hoods, flight control actuator springs, gyroscope suspension flexures, satellite deployment mechanism hinge foil | 0.025–0.20 mm / HT (TH01) peak aged | Non‑magnetic (< 1.01 permeability) eliminates compass and inertial navigation interference; exceptional fatigue resistance under cyclic loading (10⁷ cycles certified); AMS 4533 aerospace certification with full batch traceability to melt source; dimensional stability across temperature range –54°C to +125°C |
| Aircraft Electrical Systems | Electrical contactor spring leaves, connector contact blades, data transmission cable shield grounding lugs, cabin management system relay springs | 0.05–0.25 mm / AT (TF00) or HT (TH01) | Over 500 km of wired beryllium copper components across commercial aircraft platforms; resistance to vibration (20 G peak) and repeated mating cycles (50,000–100,000 cycles); FAA‑PMA (Parts Manufacturer Approval) compatibility documentation available |
| Oil & Gas / Downhole | MWD / LWD pressure housing sealing foil wraps, drill bit thrust bearing shims, subsea actuator spring stacks, valve seat wear‑layer foil, non‑sparking tool edge laminations | 0.10–0.30 mm / hot rolled + aged | Galling resistance against 17‑4PH and Inconel 718 steel components extends tool life in abrasive drilling muds; corrosion resistance in sour gas (H₂S) environments to NACE MR0175 / ISO 15156 for sub‑salt and high‑sulfur wells; zero galling with carburized steel mating surfaces |
| Precision Instrumentation | Bourdon tube raw stock (pressure gauges), bellows convolutions, diaphragm pressure sensors (0–10 psi ranges), flexible metal hose armor leaf, vibrational damping washers | 0.025–0.15 mm / mill‑hardened AT or HT | Low elastic hysteresis (≤ 0.5% of full scale) enables 0.1% pressure gauge accuracy across full range; dimensional stability across –50 °C to 200 °C with drift < 0.1% per 1,000 hours; coefficient of thermal expansion matched to Invar for temperature‑compensated assemblies |
| Automotive & EV Platforms | EV battery contact springs (liquid‑cooled and air‑cooled packs), high‑current relay blades (≥ 200 A), fuel injection solenoid springs, transmission clutch spring washers, autonomous sensor contact arrays (LiDAR, radar, camera heater contacts) | 0.05–0.25 mm / mill‑hardened AT | Stress relaxation resistance at elevated temperatures up to 200 °C maintains contact force over 1.0 × 10⁶ load cycles (validated by 100°C and 150°C test data); meets LV 214 (German automotive electrical connector specification) contact force degradation limits; IATF 16949 process certification available |
| Safety & Ordinance / Explosive Environments | Non‑sparking safety tool replacement blades (hammers, wrenches, chisels — laminated from foil stock), explosive environment equipment shim sets, ammunition feed pawl contact strips, breech mechanism wear foil | 0.10–0.40 mm / H or AT (wear‑optimized) | No spark generation upon impact (tested per ISO 19840 for explosive atmospheres); qualifies for ATEX (European Directive 2014/34/EU), IECEx (International Commission), and NFPA 77 (US National Fire Protection Association) hazardous area certification; low magnetic signature for ordinance handling in mine‑detection environments |
| MEMS & Semiconductor | Probe card contact spring blades, test socket contactors, semiconductor test handler actuator flexures, wafer‑level chip‑scale packaging (WLCSP) ground clips | 0.0125–0.08 mm / HT (TH01) or custom dual‑phase temper | Exceptional cycle life > 500,000 touchdowns in automated test equipment (ATE); consistent contact force (± 5% variation across full temperature range –40°C to +125°C); non‑magnetic eliminates interference with high‑impedance test measurements |
| Defense & Communications | Tactical radio connector contact springs, grade backplane connector blades, ruggedized handheld device battery contacts, portable power distribution relay springs | 0.05–0.20 mm / hardened HT | MIL‑PRF‑39024 (connector performance specification) conformity; survivability across shock (100 G / 10 ms half‑sine) and vibration (MIL‑STD‑810H) envelopes; 20‑year salt spray resistance per ASTM B117 with appropriate platin |
Available Forms, Dimensions & Customization
Beryllium copper foil is available in the following specification range, with customization options for coil weights, edge profiles, and plating finishes:
| Parameter | Range / Options | Tolerances & Notes |
|---|---|---|
| Thickness | Ultra‑thin range: 0.0125 mm to 0.05 mm Standard range: 0.05 mm to 0.40 mm Heavy foil (up to 0.50 mm): borderline with thin strip (> 0.50 mm refer to strip product line) |
±0.002 mm to ±0.008 mm depending on gauge; < 0.025 mm → ±25% (Goodfellow tolerance class A); 0.025–0.05 mm → ±15%; > 0.05 mm → ±10% per ASTM B194 Table 2 / BS 3B 28 Class 2. Looser tolerances available for non‑critical EMI finger stock applications. |
| Width (as‑rolled / slit) | Minimum: 1.0 mm (0.040″) Standard: 2 mm to 350 mm (0.079″ to 13.78″) Maximum (master coil): up to 625 mm (24.6″) for select gauges |
±0.05 mm for narrow widths (< 50 mm); ±0.1 mm for widths > 50 mm. Slitting to customer width performed on dedicated slitting lines with minimal camber. |
| Edge Profile Options | Slit edge (standard, cost‑optimized); Deburred edge (radius ≤ 0.05 mm for thin foil); Fully rounded edge (R‑profile, eliminates sharp burrs for medical guidewire blanking); Square edge (burr ≤ 0.01 mm for precision punch dies) | Edge condition crucial for progressive die tool life in high‑volume stamping (> 10⁶ strokes). Deburred edges reduce die wear by eliminating carbide micro‑chipping. |
| Coil ID (Inner Diameter) | 150 mm / 200 mm / 300 mm / 400 mm / 508 mm (6″ / 8″ / 12″ / 16″ / 20″) | Custom ID available on request. Smaller IDs (150 mm) preferred for lightweight automatic punch presses; larger IDs (508 mm) for high‑speed reel‑to‑reel plating and stamping lines. |
| Coil Weight | Sample coils: 5–20 kg Standard production coils: 20–300 kg Master coils (for slitting): up to 800 kg |
Weight selection affects per‑unit shipping cost and stamping line change‑over frequency. Multiple coils per pallet; export packaging to wooden crates with moisture barrier. |
| Coil OD (Outer Diameter) | Up to 1,000 mm (39.4″) maximum depending on gauge and width | Larger OD reduces coil change‑over time in automatic presses but increases shipping and handling weight. |
| Continuous Coil Length (EMI gasket stock) | Up to 10,700 mm (35 ft) in a single continuous length for finger gasket stamping | Splice‑free finished coil eliminates tool‑damaging joints and reduces material loss. Shielding effectiveness > 100 dB (plane wave, 100 MHz to 10 GHz) when correctly mounted. |
| Length (cut‑to‑length sheets) | 100 mm to 2,000 mm (custom) | Length tolerance: ±0.5 mm for lengths < 500 mm; ±1.0 mm for lengths > 500 mm. Sheets supplied interleaved with protective paper to prevent surface scratching. |
| Surface Finish Options | Bright Annealed (BA) — inert‑atmosphere bright finish, nominal Ra 0.2–0.4 μm; Pickled / Chemically Cleaned — oxide‑free for plating readiness; Precision Ground — Ra ≤ 0.08 μm for MEMS and semiconductor probe card applications; Polished (mechanical) — high‑reflectivity surface (~60% visible reflectivity) for aesthetic or optical sensing applications | Surface finish code (e.g., BA‑A for bright annealed A temper) specified on mill test certificate. Plating preparation includes pre‑cleaning for gold, silver, tin, nickel, palladium, or tin‑lead (SnPb) skip‑solder plating. |
| Flatness | Standard: ≤ 1.0 mm/m (0.012″/ft) bow; Precision: ≤ 0.5 mm/m (0.006″/ft) over entire coil length | Measured per ASTM B194 Annex A (optionally per BS 3B 28). Flatness critical for automated pick‑and‑place assembly of stamped contacts. |
| Straightness / Camber | ≤ 1.0 mm in 1,000 mm length (0.001 mm/mm) on precision slit material | Excessive camber causes tracking issues in multi‑out progressive dies. |
| Temper Options (as‑supplied) | Annealed (A / TB00), Quarter Hard (1/4H / TD01), Half Hard (1/2H / TD02), Mill‑Hardened AT (TF00), Mill‑Hardened HT (TH01), Extra Hard (H / TH02), Peak Aged (TH01 or XHM) | Temper designation per ASTM B194 and SAE J461/J463. Mill‑hardened tempers (AT/HT) require no customer‑side heat treatment — ready for immediate stamping and forming. |
| Aging Service (post‑form, for A temper) | Precipitation heat treatment performed at mill after customer‑side forming: 315 °C ± 5 °C (599 °F ± 9 °F) for 2–3 hours in protective atmosphere (argon or vacuum). | Hardness increase: from ~88 HRB (solution‑annealed) to ~38 HRC (aged) yields 3× higher tensile strength. Distortion risk minimized when parts are properly fixtured during aging cycle. Heat‑treat atmosphere prevents surface oxidation and color change. |
| Plating Compatibility & Pre‑cleaning | Pre‑cleaned surface available for gold (ASTM B488), silver (ASTM B700), tin (ASTM B545/Ff), nickel (ASTM B689), palladium, tin‑lead (SnPb), or immersion silver processes | Oxide‑free surface ensures adhesion and solderability. Full plating specifications available for automated reel‑to‑reel continuous selective plating lines. |
| Packaging Options | Eye‑to‑sky vertical coils; Eye‑to‑wall horizontal coils; Spool‑wound (for light gauge and narrow width); Cut‑to‑length sheet packs; Coil‑to‑coil (large slit coils on wooden pallet) | All coils protected with moisture‑proof VCI (vapor corrosion inhibitor) paper / polyethylene wrap and export‑grade wooden crates (ISPM 15 certified for international shipping). Desiccant included for long‑duration sea freight (> 30 days). |
| Regulatory Compliance Documentation | Mill test certificate per EN 10204 Type 3.1 (standard); EN 10204 Type 3.2 with BV/SGS verification (surcharge); RoHS / REACH compliance declaration (Europe); DFARS certification (USA defense); IATF 16949 process certification (automotive); PPAP Level 3 (automotive, custom per customer format); AMS 4533 batch traceability (aerospace); NACE MR0175 (oil & gas — on request) | Documentation lead time typically 5–10 business days after coil production. Hard‑copy and digital (PDF) copies available. |
*Notes: Material data sourced from NGK Berylco (Berylco 25), Materion (Alloy 25 Strip, formerly Brush Wellman), Robert Laminage (CuBe2), Goodfellow (Cu98/Be2 foil), MatWeb (Materion Alloy 25 Strip and Plate), AZoM (UNS C17200), eFunda Metals Division, Ulbrich (UNS C17200 alloy wire data) and Atlantic Equipment Engineers — validated for thickness range 0.0125 mm–0.40 mm.*
Frequently Asked Questions (FAQ)
Q1: What distinguishes beryllium copper foil from beryllium copper strip or tape? Where does one range end and the next begin?
“Beryllium copper foil” is functionally identical in chemistry and metallurgical behavior (UNS C17200 / CuBe2 / Alloy 25) to C17200 strip per ASTM B194, but three operational boundaries distinguish it for purchasing and engineering purposes. Thickness threshold (primary): Foil refers to gauges ≤ 0.15 mm (0.006″) per ISO and ASTM conventions, while strip covers 0.15 mm–6.0 mm. Some vendors extend “foil” classification to 0.30 mm for highly flexible applications. Width expectation: Foil typically implies narrow width (≤ 100 mm or 4″) — usually slit from wider master coils—while strip can range up to 600 mm+ widths. End‑use packaging: Foil implies continuous coiled lengths with precision edge finishing (deburred or radius edges) suitable for direct feed into automatic punch presses or reel‑to‑reel plating lines without secondary slitting. For heavy‑gauge forming operations above 0.40 mm, the strip product line is more appropriate. The category “tape” (sometimes used interchangeably) generally refers to adhesive‑backed products or EMI gasket mounting tapes—a different product family.
Q2: What is the maximum continuous length available for EMI finger stock gaskets in foil format?
Beryllium copper foil for EMI finger gaskets can be supplied in continuous coils up to 10,700 mm (35 ft) in a single uninterrupted length per standard industry packaging (frequently cited across Laird, Parker Chomerics, and other EMI gasket datasheets). Splice‑free finished coils eliminate tool‑damaging joints that would otherwise interrupt stamping press operation, reduce material scrap, and produce consistent part quality across the full coil length. Standard finger strip lengths are 406–610 mm (16–24 inches), but continuous stock lengths up to 5–10 m are available for automated high‑volume gasket production. Shielding effectiveness exceeds 100 dB for a 100 MHz plane wave when correctly mounted.
Q3: Is beryllium copper foil magnetic? Does it remain non‑magnetic after forming and stamping?
No. Beryllium copper foil exhibits a relative magnetic permeability of less than 1.01 (µᵣ ≤ 1.01, typically µᵣ ≈ 1.003–1.005 across industrially‑certified testing), making it effectively non‑magnetic. This property is retained after extensive cold working (stamping, rolling, bending, drawing) because copper‑beryllium does not undergo a martensitic transformation or form ferromagnetic phases during plastic deformation—unlike austenitic stainless steels (300‑series) which can become weakly magnetic after cold work due to strain‑induced martensite. Non‑magnetic performance is critical for high‑precision instruments (MRI scanner housings, aerospace gyroscope gimbals, naval degaussing system components, quantum computing cryogenic connectors) where µᵣ < 1.01 is a mandatory specification. Third‑party permeability certification (ASTM A342 / IEC 60404‑15) is available upon request for qualified orders.
Q4: What thickness tolerances can be held on ultra‑thin (< 0.05 mm) beryllium copper foil? How tight can tolerances go for MEMS and medical guidewire applications?
Thickness tolerance on beryllium copper foil below 0.05 mm (50 μm) follows the industry conventions below. Tighter tolerances (± 0.001 mm for gauges below 0.025 mm) are achievable for specially‑rolled MEMS and medical guidewire stock at additional cost:
| Thickness Range (mm) | ± Tolerance (mm) | ± Tolerance (μm) | Typical Application / Quality Level |
|---|---|---|---|
| 0.0125 – 0.025 | ± 0.0025 | ± 2.5 | MEMS probe card springs, medical guidewire torque cores (precision‑rolled) |
| 0.025 – 0.050 | ± 0.004 – 0.005 | ± 4 – 5 | Standard foil for medical micro‑springs, hearing aid contacts |
| 0.050 – 0.100 | ± 0.005 – 0.008 | ± 5 – 8 | Precision stamping for miniature switches, RF shielding layers |
| 0.100 – 0.150 | ± 0.008 – 0.010 | ± 8 – 10 | EMI finger stock, battery contact springs |
Tolerances refer to nominal thickness measured at centerline (ASTM B194 Section 6.2 / EN 1654 Class B). Edge thinning (cross‑sectional thickness reduction near slit edges) may occur on widths > 200 mm — consult sales engineering for your specific width/gauge combination. For applications requiring ± 1 μm thickness consistency (e.g., semiconductor probe card blades), we recommend ordering precision‑rolled stock with SPC (statistical process control) certification — lead times extended accordingly.
Q5: What is the European designation for C17200 beryllium copper foil? Does it match CW101C or CuBe2?
| Standard System | Designation | Notes |
|---|---|---|
| European EN (CEN) | CW101C (per EN 1652, EN 1654) | Full European standard designation for wrought copper‑beryllium products, including foil, strip, and sheet. |
| German DIN | 2.1247 (CuBe2) | Numeric DIN designation widely accepted for aerospace and automotive spring applications across German supply chains. |
| ISO (International) | CuBe2 (per ISO 4137, ISO 1187) | International alloy identification used in technical data sheets and global procurement packages. |
| British Standard | CuBe2 (per BS 3B 28:2009) | BS 3B 28 specifically addresses copper‑beryllium alloy strip and foil (solution treated and precipitation treated). |
European designation CW101C (EN) is fully equivalent to UNS C17200. In French standards, “CuBe1.9” is also common. Russian grade BrB2 (БрБ2) mirrors C17200 composition and is accepted for CIS region procurement. Certification to EN 10204 3.1 or 3.2 ensures acceptance across EU manufacturing, defense, and aerospace sectors. For UK‑specific government contracts, especially Ministry of Defence (MoD) procurement, BS 3B 28:2009 certification is explicitly required.
Q6: Does beryllium copper foil meet RoHS and REACH for European import? What about beryllium SVHC classification?
Yes, with clear caveats.
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RoHS (2011/65/EU) Compliance: Beryllium copper alloy C17200 (CuBe2) is not currently restricted under RoHS Directive 2011/65/EU (recast). RoHS restricts only: lead (Pb), mercury (Hg), cadmium (Cd), hexavalent chromium (Cr VI), poly‑brominated biphenyls (PBB), poly‑brominated diphenyl ethers (PBDE), and four phthalates (DEHP, BBP, DBP, DIBP). Copper‑beryllium alloys contain none of these restricted substances at above permitted limits. Standard mill test certificates for EU‑bound shipments include RoHS compliance statements.
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REACH (EC 1907/2006) Compliance: Beryllium metal is listed on the REACH Candidate List as a Substance of Very High Concern (SVHC) for carcinogenicity (H350i). However, REACH Article 33 disclosure (SVHC content > 0.1% w/w) applies to articles (finished parts) supplied to EU customers, not to raw material semi‑finished products (foil, strip, rod, wire). For raw beryllium copper foil sold to industrial downstream users, the primary obligation is to provide a Safety Data Sheet (SDS) for the substance mixture (copper‑beryllium alloy). Annex XVII restrictions do not apply to the finished alloy in solid form because the hazardous substance is bound within the alloy matrix and is not “intentionally released” under normal conditions of processing (cutting, stamping, forming). EU buyers should consult their own REACH Article 33 obligations if they incorporate finished beryllium copper foil parts — not into foil‑as‑raw‑material procurement.
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Health, Safety & Environment (HSE) Documentation: A certified SDS for copper‑beryllium alloy foil is included with each shipment to EU, UK, and REACH‑following jurisdictions (Switzerland, Norway, Iceland, Liechtenstein). For UKCA (UK Conformity Assessed) marking after Brexit, UK REACH regulations (S.I. 2019/758 with amendments) require equivalently updated SDS documentation—available upon request.
Q7: Does beryllium copper foil require post‑forming heat treatment? How do I distinguish between mill‑hardened and age‑hardenable tempers?
It depends entirely on the starting temper specification. The table below summarizes temper selection based on downstream processing requirements:
| Starting Temper | Post‑Form Heat Treatment Required? | Process Description | Final Properties After Stamp‑and‑Form | Best For… |
|---|---|---|---|---|
| Annealed (A / TB00) | YES — required | Customer‑performed age hardening: (1) solution anneal 790 °C × 4‑5 minutes, (2) water quench (≥ 50 °C/s cooling rate to suppress gamma‑phase precipitation), (3) age 315 °C ± 5 °C × 2‑3 hours in protective atmosphere (argon, nitrogen, or vacuum), (4) air or furnace cool. | Final hardness 36‑40 HRC; tensile ~1100‑1400 MPa; elongation 4‑10%. Full precipitation density only achieved after heat treatment. | Deep‑drawn cups, complex 3D forming, parts with severe deformation where mill‑hardened material would crack during forming. |
| Quarter Hard (1/4H) / Half Hard (1/2H) | YES — required for strength | Same age hardening cycle as A‑temper. The initial cold work (19% thickness reduction for 1/2H) plus subsequent precipitation hardening produces higher tensile strength (~200 MPa higher) than age‑hardening from fully annealed condition. | Tensile 1200‑1450 MPa; elongation 2‑6%; hardness 38‑43 HRC | Moderate forming with strength benefit after heat treatment. |
| Mill‑Hardened AT (formerly AT, now TF00) | NO — ready to use | Fully aged at the mill (315 °C × 3 hours). No customer‑side heat treatment required after stamping/forming. Supplied in peak‑aged condition. | Immediate spring function upon stamping; hardness 36‑40 HRC; tensile 1100‑1400 MPa; elongation 4‑10%. | High‑volume progressive die stamping of springs, connectors, contact blades, and EMI fingers (most common for foil). |
| Mill‑Hardened HT (formerly HT, now TH01) | NO — ready to use | Full age hardening at mill (315 °C × 2‑3 hours) applied after cold work. Highest strength temper. | Hardness 38‑45 HRC; tensile 1205‑1480 MPa; elongation 2‑6%. | Aerospace connectors, membranes for pressure sensors, high‑cycle leaf springs, bourdon tube stock. |
Selection Rule of Thumb : For production volumes above 50,000 pcs/month and part geometry does not require tight radii (< 1× metal thickness), specify mill‑hardened AT or HT to eliminate post‑processing steps, reduce distortion risk (parts do not move during aging), and lower per‑part cost. For low‑volume prototypes, R&D, or parts with severe forming requirements (radii < 0.5× thickness), specify annealed A‑temper and age‑harden after forming — but note that heat‑treat fixturing is required to prevent distortion during the aging cycle (parts deform under their own weight at 315 °C). Mill‑hardened materials are not subject to distortion because the aging occurs before forming—no further heat treatment is needed once parts are stamped.
Q8: Can beryllium copper foil be welded? What methods are recommended for ultra‑thin material (< 0.1 mm)?
Yes, with method recommendations specific to ultra‑thin foil. The table below summarizes feasibility and parameters for each welding method:
| Welding Method | Feasibility for Foil (≤ 0.1 mm) | Recommended Parameters & Notes |
|---|---|---|
| Resistance Spot Welding (RSW) | Best choice — the most reliable method for thin‑to‑thin and thin‑to‑thick configurations | Foil thickness 0.05–0.25 mm; Use RWMA Class 2 electrodes (copper‑chromium‑zirconium), moderate electrode force (50–100 N to avoid extrusion), short weld time (1–3 AC cycles / 0.016‑0.05 seconds), low weld current (0.5–3.0 kA depending on thickness). Pre‑cleaning (isopropyl alcohol) recommended. Post‑weld aging (315 °C × 2 h) restores strength after HAZ overaging for HT/AT tempers. |
| Laser Welding (Pulsed Nd:YAG / Fiber) | Excellent — minimal heat input, minimal HAZ (50 μm typical) | Pulse energy 0.2–2.0 J; Pulse width 1–5 ms; Spot diameter 0.1–0.5 mm; Travel speed 5–15 mm/s. Argon shielding gas (5–15 L/min). For foil < 0.05 mm, back‑side support required to prevent melt‑through. Post‑weld aging optional but recommended for structural weldments (restores 80‑90% of base metal strength). |
| Micro‑TIG Welding | Marginal for very thin foil — risk of burn‑through is high below 0.1 mm | For 0.10–0.30 mm only. Use smallest tungsten (0.5–1.0 mm diameter), minimal current (5‑20 A), pulse mode, automated manipulation. Backing bar with argon purge required. Not recommended for routine production below 0.08 mm due to high reject rate. |
| Soldering (Manual / Reflow) | Highly recommended — easiest method for electrical connections | Use Sn95/Ag5 (eutectic, 221 °C melting point) or Sn96.5/Ag3.5/Cu0.5 (SAC305) for RoHS compliance. Flux‑cored or flux‑coated surfaces (rosin‑based, no‑clean). Hand soldering iron temperature 260‑350 °C, contact time < 3 seconds to avoid overaging. Hot‑air reflow for reel‑to‑reel selective soldering. |
| Brazing (Torch / Furnace) | Acceptable with temperature control | Brazing temperature must remain below 790 °C (1450 °F) to avoid solution annealing of the foil. Cycle time minimized (< 15 sec). AWS filler: BAg‑8a (silver‑copper‑tin, 630‑730 °C liquidus) for highest ductility; BCuP‑5 (silver‑copper‑phosphorus) for self‑fluxing on copper‑rich surfaces. Brazing in nitrogen or argon protective atmosphere to prevent oxidation. Post‑braze aging restores near‑original properties (315 °C × 2 h). |
Critical notes for foil welding:
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For mill‑hardened HT/AT tempers, local annealing in the heat‑affected zone (HAZ) will occur — post‑weld re‑aging at 315 °C for 2 hours typically restores 80‑90% of original strength, depending on weld geometry.
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For annealed A‑temper foil, welding followed by full age hardening cycle (790 °C solution treat → quench → 315 °C age) yields mechanical properties equivalent to unwelded base metal.
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Filler metal recommendation for TIG / laser applications: AWS ERCuBe‑A or ERCuBe‑Al for matched composition and corrosion resistance — avoids galvanic effects in salt‑spray or marine environments.
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Avoid oxyacetylene welding entirely in any thickness — heat input too high, causes overaging and grain coarsening.
Q9: What safety precautions are required when processing beryllium copper foil?
Solid beryllium copper foil (as‑rolled coils, stamped parts, or cut lengths) poses no inhalation hazard — the beryllium is metallurgically bound within the copper matrix and is not airborne under normal handling, stamping, forming, or bending conditions. However, during grinding, sanding, polishing, welding, brazing, or any machining operation that generates airborne dust or fume, beryllium‑containing particles may be released. The following safety measures are mandatory for downstream processors:
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Dust and fume control: Use local exhaust ventilation (LEV) with HEPA filtration (≥ 99.97% efficiency at 0.3 μm) or wet machining (water‑based coolant / mist control) to capture particles at the source before they become airborne.
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Respiratory protection: Wear NIOSH‑approved P100 or HEPA‑filtered respirators (APF ≥ 10) for any process generating visible dust or fume. Full facepiece or powered air‑purifying respirator (PAPR) recommended for grinding operations.
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Housekeeping: NEVER dry sweep beryllium‑containing dust. Use HEPA‑vacuum (Class H, certified for beryllium) or wet wiping method. Compressed air blowing of surfaces is prohibited unless exhaust ventilation captures the dispersed aerosol.
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OEL / TLV compliance: Beryllium OSHA PEL (Permissible Exposure Limit) is 0.2 μg/m³ (8‑hour TWA); ACGIH TLV is 0.05 μg/m³ (inhalable fraction). Many jurisdictions follow the more stringent ACGIH TLV. Air monitoring required for qualifying processes.
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OSHA compliance (USA) : Copper‑beryllium alloy processing falls under OSHA 29 CFR 1910.1024 (Beryllium standard), which requires exposure assessment, written compliance program, medical surveillance for employees exposed above the action level (0.1 μg/m³), and change rooms / shower facilities for certain operations.
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Material Safety Data Sheet (SDS) : A current SDS for beryllium copper alloy (CAS 7440‑41‑7 beryllium content) is provided with each shipment. Review prior to processing. Available in US‑OSHA, EU‑REACH, and UK‑REACH formats.
Key distinction for product liability : End‑user processing safety is the responsibility of the downstream processor (the company operating grinding, welding, or sanding equipment). As a raw material supplier, we provide HSE documentation and alloy composition data to enable safe handling, but appropriate engineering controls must be implemented by the processor according to local occupational health regulations.
Q10: How do I select between C17200 beryllium copper foil and alternative beryllium‑copper grades (C17510, C17300, C17500)?
| Property | C17200 (Alloy 25 / CuBe2) | C17510 (CuNi2Be) | C17300 (CuBe2Pb) | C17500 (CuCo2Be) |
|---|---|---|---|---|
| Beryllium content | 1.80‑2.00% | 0.20‑0.60% | 1.80‑2.00% (with added Pb) | 0.40‑0.70% |
| Tensile strength (max) | Up to 1500 MPa (218 ksi) | Up to 800 MPa (116 ksi) | Up to 1480 MPa (215 ksi) | Up to 760 MPa (110 ksi) |
| Electrical conductivity | 22‑28% IACS | 45‑60% IACS | 18‑22% IACS | 45‑55% IACS |
| Relative machinability rating | 20% | ~35‑40% | 60‑70% | ~40‑50% |
| Thermal conductivity | 105‑135 W/m·K | 190‑210 W/m·K | 100‑120 W/m·K | 170‑190 W/m·K |
| Lead content | ≤ 0.01% (RoHS compliant) | Trace | ~0.4‑0.7% (not RoHS compliant) | Trace |
| Formability (annealed temper) | Excellent — bends flat on itself | Good | Reduced (lead inhibits formability) | Good |
| Spring performance relative to C17200 (same cross‑section) | Baseline = 1.0 (highest) | ~0.6 | ~0.95 | ~0.55 |
| Typical application | Connector springs, EMI gaskets, medical guidewires, instrument diaphragms | Resistance welding electrodes, high‑current bus bars, circuit breaker contacts | Automatic screw‑machined precision components (small diameter) | Welding wheels, mold cores, brake resistor terminals |
Selection guidance : Use C17200 beryllium copper foil when the application demands the highest possible spring force in the thinnest available cross‑section (typically foil gauge ≤ 0.15 mm) and conductivity above 20% IACS is sufficient. Use C17510 / C17500 when heat dissipation (thermal conductivity > 170 W/m·K) or > 45% IACS conductivity outweighs peak strength — but these grades are rarely available in foil thicknesses below 0.20 mm (typically restricted to bar, rod, heavy plate, and wire). Use C17300 when machinability (screw‑machined parts) is the priority — but this grade is not RoHS compliant due to lead content (Pb ~0.5%) and is typically used for bar‑turned precision components rather than foil stamping.
For the vast majority of foil‑based spring and contact applications (EMI finger stock, battery contact springs, connector blades, MEMS springs, medical guidewires), C17200 (Alloy 25 / CuBe2) is the correct selection.
Q11: What is the European equivalent designation for C17200 beryllium copper foil?
| Standard System | Designation | Application Context |
|---|---|---|
| EN (European Norm / CEN) | CW101C (EN 1652 / EN 1654) | Full European standard designation for wrought copper‑beryllium alloy — plate, sheet, strip, foil, and rolled bar. |
| DIN (German Institute for Standardization) | 2.1247 (CuBe2) | Numeric designation widely accepted across German automotive (VDA), aerospace, and precision engineering supply chains. |
| ISO (International Organization for Standardization) | CuBe2 (ISO 4137, ISO 1187) | International alloy identification used in global technical data sheets, academic research publications, and international procurement packages. |
| British Standard | CuBe2 (BS 3B 28) | BS 3B 28:2009 specifically titled “Specification for copper‑beryllium alloy strip and foil (solution treated and precipitation treated)” — explicitly includes foil as a covered form. Recommended for UK Ministry of Defence (MoD) and other UK government‑specified contracts. |
| French (NF) | CuBe1.9 | Also common in French technical literature and aerospace specifications. |
| Russian (GOST) | BrB2 (БрБ2) | Equivalent composition; accepted for CIS region procurement. |
| Japanese (JIS) | C1720 — no “W” or “R” designation differs, but substance same as C17200 | JIS H3130 standard for beryllium copper sheets, plates, and strips. |
Certification to EN 10204 3.1 (standard mill certificate) or 3.2 (third‑party verified) ensures acceptance across EU manufacturing, defense, and aerospace sectors. For UK‑specific government contracts, especially UK Ministry of Defence (MoD) aerospace procurement, BS 3B 28:2009 certification is explicitly required.
Q12: What is the proper storage, shelf life, and handling procedure for beryllium copper foil coils? Does it tarnish over time?
Storage Conditions: Store beryllium copper foil in its original moisture‑resistant packaging (VCI paper + polyethylene wrap) in a clean, dry indoor environment at 5 °C to 35 °C (40 °F to 95 °F) with relative humidity < 60%. Avoid exposure to:
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Acidic or alkaline fumes (including nearby pickling lines, battery charging areas, or chemical storage)
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Direct contact with concrete floors (concrete retains moisture and can surface‑tarnish copper over time)
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Outdoor or unheated warehouse storage where condensation cycles occur during temperature transitions
Shelf Life: Under proper storage conditions (sealed VCI packaging, stable temperature, humidity < 60%):
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Unopened packaging (sealed VCI bag) : ≥ 24 months with no visible tarnish. VCI (vapor corrosion inhibitor) chemicals protect copper surfaces by forming a monomolecular barrier.
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Opened coil (partial usage, repackaged with fresh VCI) : 12 months if rewrapped with care, dry atmosphere.
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Ambient storage (open reel, no protection) : 3–6 months — expect light surface tarnish (darkening) depending on local air quality.
Tarnish Appearance and Significance: Surface tarnish (oxidation) appears as darkening from bright pink‑copper to bronze, brown, or dark grey. In most spring and contact applications, light surface tarnish does not affect mechanical spring performance or fatigue endurance (tarnish depth is typically < 0.5 μm). However, tarnish does:
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Increase electrical contact resistance (tarnish layer resistive) — critical for low‑voltage signal contacts (< 5 V / < 50 mA). For such applications, specify tin, silver, or gold plating or request foil with tarnish‑inhibitor film.
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Reduce solderability (tarnish inhibits wetting) — use de‑oxidizing flux (activator‑containing rosin) or perform light acid cleaning (5‑10% citric acid dip) before soldering.
Tarnish Removal: For applications requiring oxide‑free surface after storage:
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Light tarnish (bronze color) → isopropyl alcohol + soft wipe, or 5‑10% citric acid dip (room temperature, 10–30 seconds) followed by deionized water rinse and nitrogen blow‑drying.
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Heavy tarnish (dark brown to black) → mild abrasive pad (Scotch‑Brite 7447) or alkaline cleaning (sodium metasilicate solution) is required. Replace with fresh plating after heavy tarnish removal if electrical performance is critical.
Best Practice Recommendation for production inventory: Schedule foil coil consumption on a first‑in, first‑out (FIFO) basis. For stocks held longer than 12 months, open one package for periodic visual inspection. If tarnish extends more than a light bronze coloration across the full surface, contact sales engineering for re‑pickling or replacement guidance. Avoid storing different beryllium tempers (annealed vs. mill‑hardened) mixed on the same shelf without label segregation—they are visually indistinguishable.
Q14: Can beryllium copper foil be supplied in anti‑tarnish or pre‑plated condition for extended shelf life? What plating options are available?
Yes — multiple surface finish options are available for beryllium copper foil to extend shelf life, improve solderability, enhance corrosion resistance, or prepare for high‑reliability electrical contacts.
| Surface Treatment / Plating | Primary Benefit | Typical Thickness | Shelf Life (ambient storage) | Notes |
|---|---|---|---|---|
| Tarnish‑Inhibitor Film (organic) | Extended storage without oxidation | < 0.5 μm | ≥ 18 months in sealed package; ≥ 12 months after opening (re‑wrapped with VCI) | Removed by isopropyl alcohol wipe; does not significantly affect contact resistance (removed during first insertion cycle). Recommended for standard spring and contact applications requiring immediate assembly but not soldering. |
| Tin Plating (matte or bright) | Superior solderability; moderate contact resistance (ASTM B545) | 2.5 – 7.5 μm (100‑300 μ″) | ≥ 36 months | Most common for automotive, consumer electronics, and industrial power contacts. Reflowable. |
| Silver Plating (ASTM B700) | Highest conductivity; lowest contact resistance | 2.5 – 10 μm (100‑400 μ″) | ≥ 24 months (may darken on prolonged air exposure but conductivity unaffected) | Preferred for high‑frequency (RF) connectors, high‑power contacts (> 50 A). Tarnish does not impair electrical performance, but darkening appearance may require bright finish for aesthetic applications. |
| Gold Plating (ASTM B488 / MIL‑G‑45204) | Zero oxidation; lowest and most stable contact resistance; excellent corrosion protection | 0.25 – 2.5 μm (10‑100 μ″) ENIG; optional 1.25 μm (50 μ″) hard gold for high‑cycle wear | ≥ 48 months (indefinite with proper storage) | Preferred for low‑level signal contacts (< 50 mV, < 10 mA), medical implants (biocompatible), space and defense electronics. Hard gold (with Co or Ni hardener) for high‑cycle applications; soft gold for wire bonding. |
| Nickel Plating (ASTM B689) | Barrier layer against copper diffusion; improves adhesion of gold or silver topcoats; corrosion resistance | 1.25 – 5.0 μm (50‑200 μ″) underplate | Indefinite with topcoat | Typically used as an underplate. Not typically used as final finish for springs (reduced spring force due to stress from nickel coating unless very thin). |
| Palladium (Pd) or Palladium‑Nickel (PdNi) | Hard, low‑friction surface; lower galling than gold; cost advantage for selective plating | 0.5 – 1.5 μm (20‑60 μ″) over nickel strike | ≥ 24 months (no oxidation) | Emerging alternative to hard gold for high‑volume connector and MEMS applications. |
Plating application methods :
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Pre‑plated foil (mill‑applied) : Plating applied to master coil before slitting and stamping. Most common for tin and silver.
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Reel‑to‑reel selective plating (post‑slitting) : Pre‑plating of entire coil outside of foil supplier‘s scope — can be performed by independent electroplating contractors with reel‑to‑reel selective and spot‑plating capabilities. We can recommend qualified vendors.
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Selective (strip) plating after stamping : Plating applied only to functional areas (e.g., contact tips) after blanking and forming — best for gold and palladium to minimize precious metal usage.
For extended shelf life requests (≥ 18 months) : Order tarnish‑inhibitor coated foil (organic protectant) completed at final slitting before export packaging. Shelf life tested to ≥ 18 months under standard storage (5‑35 °C, < 60% RH, no corrosive gas environment).