CuSn6 Phosphor Bronze Strip

CuSn6 Phosphor Bronze Strip – High-Strength, Fatigue-Resistant Alloy for Connector Springs & Electrical Contacts

CuSn6 Phosphor Bronze Strip is a tin-phosphor bronze containing approximately 6% tin, offering an optimal balance of high strength, excellent fatigue resistance, and good electrical conductivity. As a leading CuSn6 strip supplier, we provide precision-rolled strip in tempers from soft to extra-hard, engineered for connector springs, terminals, switch contacts, and precision-stamped components.

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Product Overview

CuSn6 (UNS C51900 / EN CW452K / JIS C5191) is one of the most widely specified phosphor bronze alloys for electrical and electronic applications. The 6% tin content combined with phosphorus addition delivers:

Higher strength and elasticity than lower-tin phosphor bronzes
Excellent fatigue resistance for repeated deflection cycles
Good corrosion resistance in industrial and marine atmospheres
Reliable spring properties for long-term contact force retention

Phosphor bronze strip is commonly used for deep drawing into bellows, stamping and forming into spring devices, and terminals and connectors for electrical apparatus. CuSn6 specifically is suitable where a component must flex repeatedly without permanently losing its functional shape.

Key Features & Benefits

1. High Fatigue Resistance

CuSn6 strip exhibits fatigue life exceeding 1 million cycles, making it ideal for high-frequency elastic components in connectors and switches. The alloy maintains functional spring behavior under repeated deformation.

2. Excellent Elasticity

With an elastic modulus of about 115 GPa and an elastic limit up to 500 MPa, CuSn6 provides reliable contact force for precision spring applications.

3. Superior Corrosion Resistance

The alloy resists atmospheric, seawater, and weak-acid corrosion, with a corrosion rate of ≤0.005 mm/a, making it suitable for harsh environments, including marine hardware and industrial instrumentation.

4. Good Formability

CuSn6 strip supports cold/hot working, welding, and brazing, with excellent stamping and forming characteristics for high-volume production.

5. Controlled Impurity Levels

Lead content is strictly controlled to ≤0.02%, avoiding brittleness while maintaining material purity and consistency.

Technical Specifications

Chemical Composition (wt%)

Element	CuSn6	Function
Cu	Balance (≥93.5%)	Base material, ensures conductivity and corrosion resistance
Sn	5.5 – 7.0%	Enhances elasticity, wear resistance, and corrosion resistance
P	0.10 – 0.35%	Deoxidizer, refines grain structure, improves wear resistance
Pb	≤0.02%	Strictly controlled to avoid brittleness
Fe	≤0.10%	Impurity control
Zn	≤0.20%	Residual element
Others	≤0.20%	Total impurities

Values in weight %.

Mechanical Properties

Temper	Tensile Strength (N/mm²)	Elongation (%)	Hardness (HV)
Soft (O)	≥290 – 400	≥35 – 40	80 – 180
1/4 Hard (H02)	390 – 510	≥35	100 – 160
1/2 Hard (H04)	440 – 570	≥8	150 – 205
Hard (H06)	540 – 690	≥5	180 – 230
Extra Hard (H08)	≥640	≥2	≥200

Properties vary with thickness and processing conditions.

Physical Properties

Property	Value	Remarks
Density	8.82 – 8.9 g/cm³	High density for precision parts
Electrical Conductivity	13 – 16% IACS	Suitable for electrical contacts
Thermal Conductivity	60 – 75 W/(m·K)	Moderate heat dissipation
Elastic Modulus	≥115 GPa	Critical for spring applications
Melting Point	995 – 1050°C

Available Forms & Sizes

Form	Size Range	Temper
Strip/Coil	Thickness: 0.05 – 2.0mm; Width: < 600 mm	O, 1/4H, 1/2H, H, EH
Sheet	Thickness: 0.1 – 1.5mm; Width: 10 – 200mm	O, 1/2H, H
Rod	Diameter: 5 – 150mm	Drawn, Hot-Rolled
Wire	Diameter: 0.05 – 8.0mm	Soft, Half-hard

Custom sizes and profiles available upon request.

Applications

Electronics & Electrical

Connector springs and terminals
Relay springs and switch contacts
EMI shielding components
Probe card springs for semiconductor testing

Precision Engineering

Stamped parts requiring wear resistance and high mechanical strength
Diaphragms and bellows
Spring contacts for electrical apparatus

Automotive

High-pressure fuel system precision springs
Sealing rings for corrosion and pressure resistance

Marine & Industrial

Seawater-resistant valves and sensor components
Components in paper and textile manufacturing plants
Marine hardware and instrument components

Processing Guidelines

Process	Recommendation
Annealing	650 – 750°C for 1-2 hours (post-cold working)
Stress Relief	200 – 350°C
Welding	Laser or electron beam welding preferred; brazing strongly recommended
Machining	Cutting speed ≤50 m/min; carbide tools with oil-based coolant
Surface Preparation	Clean thoroughly before plating to ensure adhesion

Quality Assurance

Each order ships with:

Mill Test Certificate (MTC) – chemical composition, mechanical properties

Dimensional Inspection Report – thickness, width, tolerance verification

Surface Quality Report – visual and dimensional checks

Material Traceability – lot and heat number tracking

Compliant Standards: ASTM B103/B103M, EN 1652/1654, GB/T 2059-2000, JIS H3110.

Why Choose Our CuSn6 Phosphor Bronze Strip?

Consistent Quality: Strict tolerance control on thickness and width, with each coil verified for hardness and mechanical properties.

Flexible Order Quantities: From prototyping (low MOQ) to production-scale volumes, with stable bulk supply capability.

Fast Lead Time: 10-15 days after PO confirmation for standard specifications.

Technical Support: Our metallurgical team assists with temper selection, forming parameters, and application-specific recommendations.

Custom Solutions: OEM/ODM support based on drawings, samples, or specific technical requirements.

Frequently Asked Questions

Q: What is the difference between CuSn6 and CuSn8?
A: CuSn8 (C52100) contains 8% tin, offering higher strength and hardness but lower electrical conductivity than CuSn6. CuSn6 provides a better balance of spring performance and formability for most connector applications.

Q: What temper should I choose for connector spring applications?
A: The optimal temper depends on your forming process and required contact force. Harder tempers (H04–H06) provide higher strength and resistance to deformation, while softer tempers (O–H02) offer better formability. We recommend specifying temper based on the final spring geometry and working stress.

Q: Is CuSn6 suitable for high-temperature applications?
A: CuSn6 maintains good mechanical properties at moderate temperatures. For extended high-temperature service, consider stress-relief annealing at 200–350°C to optimize performance.

Q: What is the minimum order quantity?
A: MOQ varies by product form and specification. Contact our sales team for current lead times and minimum quantities.

Q: Can you provide RoHS-compliant material?
A: Yes. We offer CuSn6 strip with lead content controlled below 100 ppm, with RoHS compliance reports available.

Request a Quote

Ready to specify CuSn6 Phosphor Bronze Strip for your application? Contact us with your requirements:

Alloy: CuSn6 / C51900 / CW452K

Form: Strip / Coil / Sheet

Thickness: ______ mm

Width: ______ mm

Temper: ______ (O / 1/4H / 1/2H / H / EH)

Quantity: ______ kg

Application: ______

Our team responds within 24 hours with pricing, lead time, and technical recommendations.

CuSn6 Phosphor Bronze Strip Manufacturer & Supplier – Precision Copper Alloy Solutions for Connector Springs, Terminals, and Electrical Contacts. Email: [email protected]