Complete Datasheet: Stamped Electrical Terminals Copper Alloy Properties
An FEA model loaded with generic copper property data cannot predict cold-work conductivity derating, stress relaxation at elevated temperatures, or work-hardening localization at tight bend radii. These three failure modes emerge only when material data matches the stamped part’s actual alloy and temper condition.
In this reference, you will find mechanical, thermal, and processing data for five copper alloy families (C11000, Brass 260, C51000, C17200, C19400) anchored in ASTM test methods for direct FEA material card import.
Read the full comparative datasheet.
Mechanical & Physical Properties
Five copper alloy families serve stamped electrical terminals, each occupying a distinct band on the strength-versus-conductivity map. The selection decision determines minimum bend radius, contact normal force ceiling, long-term fretting resistance, and whether the terminal can function as a current-carrying spring member or only as a structural grounding path. For an overview of how alloy selection impacts production cost and lead time, see stamped terminal production capabilities.
Tensile & Yield Across Copper Alloy Grades
Tensile strength across the five alloy families spans from 220 MPa for annealed C11000 copper to 1380 MPa for age-hardened C17200 beryllium copper. Annealed C11000 enters the die at 220-250 MPa tensile with 45% elongation, forming easily but offering minimal spring contact force in the finished terminal. Age-hardened C17200 reaches 965-1100 MPa yield strength with elongation dropping to 3-10%, which drives cracking risk at bend radii below 3.0 t.
Yield strength is the forming threshold that determines the force the progressive die must overcome. C19400 (copper-iron-phosphorus) at half-hard temper delivers 380-450 MPa yield with 18% elongation, occupying the middle ground between pure copper formability and beryllium copper strength. Brass 260 half-hard at 310-415 MPa with 23% elongation provides the widest forming window for multi-bend terminal geometries. Phosphor bronze C51000 spring temper at 690-760 MPa tensile with 8% elongation delivers the highest contact normal force among non-beryllium alloys but demands tighter springback compensation in tooling design.
Elongation at break is the forming safety margin for tight bend radii. C11000 at 45% elongation forgives small clearance variations across progressive stations. C17200 at 3-10% elongation requires accurate bend radius control and solution-treated strip condition (AT temper) before stamping, with age hardening performed after forming to avoid cracking.
Hardness follows the same ranking: annealed C11000 at 45-55 HV, C19400 at 120-145 HV, Brass 260 at 110-140 HV, C51000 spring temper at 180-210 HV, and age-hardened C17200 at 350-420 HV.
| Property | C11000 (Annealed) | Brass 260 (Half-Hard) | C51000 (Spring) | C17200 (Age-Hardened) | C19400 (Half-Hard) |
|---|---|---|---|---|---|
| Tensile Strength | 220-250 MPa | 310-415 MPa | 690-760 MPa | 1170-1380 MPa | 440-520 MPa |
| Yield Strength (0.2% offset) | 70-110 MPa | 240-350 MPa | 550-620 MPa | 965-1100 MPa | 380-450 MPa |
| Elongation at Break | 45% | 23% | 8% | 3-10% | 18% |
| Hardness | 45-55 HV | 110-140 HV | 180-210 HV | 350-420 HV | 120-145 HV |
| Elastic Modulus | 117 GPa | 110 GPa | 110 GPa | 128 GPa | 121 GPa |
All values assume room-temperature testing at 23 degree C per ASTM E8 conditioning requirements. Yield strength drops approximately 8-12% for C11000 and 5-8% for C51000 when ambient temperature reaches 75 degree C, a condition common inside sealed automotive engine-bay connectors.
[Data Anchor]: Yield strength spans from 70 MPa (annealed C11000) to 1100 MPa (age-hardened C17200). C11000 is suitable only for non-spring-beam terminals at room temperature with contact normal force below 1.5 N. Terminals requiring above 8 N contact force must select C17200 or spring-temper C51000, both of which maintain structural stiffness above 5 N at elevated temperatures.
Electrical Conductivity Ranking
Electrical conductivity measured as percent IACS is the primary functional metric for current-carrying stamped electrical contacts. C11000 delivers 101% IACS in annealed condition, making it the benchmark against which all other copper alloys are measured. C19400 follows at 65% IACS, offering the optimal conductivity-strength balance for terminals carrying above 5 A continuous current without requiring pure copper formability limits.
Brass 260 drops to 28% IACS, adequate for mechanical grounding terminals where force retention matters more than current capacity. C17200 beryllium copper measures 22% IACS, and phosphor bronze C51000 measures 15% IACS, positioning both exclusively for signal-level contacts and spring-force-dependent applications where conductivity takes a secondary role.
Cold working after forming reduces C11000 conductivity by 2-5% IACS. This derating occurs because plastic deformation introduces dislocation densities on the order of 10^12 to 10^14 lines per square metre. Each dislocation acts as a scattering center for conduction electrons.
The mean free path of electrons in high-purity copper (approximately 40 nm at room temperature) is reduced by a factor of 2-3 at these densities. This directly increases electrical resistivity by 2-5% depending on the degree of cold reduction. FEA electrical-thermal coupled simulations must include this forming-induced conductivity loss when modeling terminal Joule heating at continuous currents above 5 A.
Contact resistance consists of two components: bulk resistance governed by percent IACS and constriction resistance governed by contact area and surface oxide films. A C11000 terminal with 0.5 mm thickness and 5 mm squared contact area contributes approximately 0.35 milliohm bulk resistance. The same geometry in C51000 contributes 2.4 milliohm. This 7x increase becomes significant in circuits carrying above 5 A continuous current.
[Data Anchor]: C11000 conductivity of 101% IACS degrades to a minimum of 96% IACS after 50% cold reduction due to dislocation-induced electron scattering. C19400 at 65% IACS offers the optimal balance for terminals carrying 5-15 A continuous current. Terminal designs above 10 A must derate current capacity by 5% to account for forming-induced conductivity loss.
Elastic Modulus & Spring Force Retention
Elastic modulus determines the contact beam stiffness that generates normal force at a given deflection. C17200 beryllium copper at 128 GPa produces the stiffest contact beam, followed by C19400 at 121 GPa, C11000 at 117 GPa, and Brass 260 and C51000 both at 110 GPa. A 15% modulus difference between C17200 and C51000 translates to a 15% difference in contact normal force at identical beam geometry and deflection.
The yield-to-modulus ratio predicts springback behavior. C11000 at a ratio of approximately 0.0008 requires only 2-4 degrees of overbend for a 90 degree target angle. C17200 at a ratio of approximately 0.008 demands 12-18 degrees of overbend — a 10x range that drives fundamentally different tooling compensation strategies. Terminal designs that switch from C11000 to C17200 at the same geometry without retooling the bend stations will produce parts that miss the dimensional print by 8-14 degrees.
Stress relaxation at elevated temperature — the time-dependent conversion of elastic strain into permanent set — follows a distinct ranking. C17200 retains 95% of initial contact force after 1000 hours at 150 degree C. C19400 retains 88% at 125 degree C.
C51000 retains 85% at 125 degree C. Brass 260 drops to 82% at 100 degree C. C11000 at 100 degree C retains only 80% of initial force over 1000 hours.
This means C11000 and Brass 260 are excluded from contact beam material selection for any terminal operating above 80 degree C ambient. Terminal designs requiring contact normal force above 2.5 N for tin-plated contacts at elevated temperatures must specify C17200, C19400, or C51000.
[Data Anchor]: C17200 beryllium copper retains 95% of initial contact force after 1000 hours at 150 degree C. C11000 drops to 80% retention at 100 degree C over the same period. Terminal designs operating above 100 degree C must exclude C11000 and Brass 260 from contact beam material selection. The yield-to-modulus ratio difference between C11000 (0.0008) and C17200 (0.008) drives a 10x range in springback compensation requirement from 2 degrees to 18 degrees at 90 degree bend geometry.
Thermal & Environmental Limits
Thermal derating hits copper alloys on three fronts simultaneously. Yield strength drops, resistivity rises, and stress relaxation accelerates. The five alloy families diverge sharply in their thermal tolerance windows.
Review our quality and testing protocols for validated thermal performance data across all five alloy families.
Stress Relaxation at Elevated Temperatures
Stress relaxation is time-dependent plastic strain under constant deflection. The mechanism involves dislocation climb at elevated temperature, where thermal activation enables dislocations to bypass pinning points and gradually replace elastic strain with permanent set. The rate depends on homologous temperature (the ratio of operating temperature to melting point) and on alloy-specific precipitation or solid-solution strengthening that pins dislocation motion.
C11000 at 100 degree C loses 5% of initial contact force after 1000 hours. Brass 260 loses 8% at the same temperature and duration because zinc-atom diffusion within the alpha-brass lattice accelerates dislocation climb. C51000 tolerates 125 degree C with only 3% force loss after 1000 hours due to tin-atom pinning of grain boundary dislocations.
C19400 at 125 degree C loses approximately 4%. C17200 loses less than 2% at 150 degree C over 1000 hours because nanoscale beryllide precipitates (BeCu and Be2Cu) effectively immobilize dislocation motion at temperatures up to 175 degree C.
The functionally significant threshold occurs when contact force drops below 2.0 N for tin-plated contacts per IEC 60512-2. C11000 crosses this threshold at 100 degree C within 2000 hours.
C51000 at 125 degree C crosses it after approximately 5000 hours. C17200 at 150 degree C remains above 2.0 N beyond 10,000 hours.
[Data Anchor]: C17200 beryllium copper operating ceiling is 150 degree C continuous with less than 2% force loss at 1000 hours. C11000 copper must not exceed 100 degree C for contact-beam applications. Exceeding 125 degree C with phosphor bronze C51000 triggers relaxation above 15% force loss within 500 hours, sufficient to cause intermittent electrical contact in mated connectors.
Corrosion Resistance by Alloy Family
Galvanic corrosion risk arises when a copper-alloy terminal mates with an aluminum conductor or steel connector body. The driving force is the difference in anodic potential. C11000 measures 0.35 V versus a saturated calomel electrode.
Aluminum conductors measure 0.75 V. The 0.40 V difference exceeds the 0.25 V threshold commonly accepted for dry indoor environments. Under humid or salt-spray conditions per USCAR-2, the allowable potential difference tightens to 0.15 V, which no unplated copper alloy can satisfy against aluminum.
Tin plating over C11000 at a minimum of 2.5 micrometre thickness shifts the effective surface potential and eliminates the couple, provided plating porosity remains below 5 pores per square millimetre.
Environmental corrosion mechanisms differ by alloy family. Brass 260 carries a dezincification risk in acidic environments below pH 5 or in chloride-containing atmospheres above 50 ppm concentration.
Selective leaching of zinc from the alpha-brass matrix leaves a porous copper sponge structure that loses 40-60% of original tensile strength within 6 months of continuous exposure. C17200 exhibits excellent general corrosion resistance with a beryllium oxide surface film (5-10 nm) that passivates the surface, though hexavalent beryllium compounds formed during laser marking or welding require ventilation protocols per OSHA 29 CFR 1910.1024.
C19400 benefits from iron-phosphide grain boundary pinning that reduces intergranular corrosion susceptibility. C51000 resists both dezincification and stress-corrosion cracking in chloride environments, passing 96-hour ASTM B117 salt spray testing with no visible pitting at 0.3 mm material thickness.
C19400 passes 120 hours under the same conditions. C17200 passes 200 hours, making it suitable for aerospace and defense connectors exposed to salt fog per MIL-STD-810.
[Data Anchor]: Unplated C11000 copper forms a galvanic couple with aluminum conductors at an anodic potential difference of 0.40 V. This exceeds both the 0.25 V dry indoor threshold and the 0.15 V humid-environment limit per USCAR-2. A minimum 2.5 micrometre tin barrier plating with porosity below 5 pores per square millimetre is required for any copper alloy terminal mating with aluminum in environments above 60% relative humidity.
Processing Behaviors & Morphology
Tensile data predicts none of the four variables that dominate progressive die design: blanking clearance, springback angle, bend radius limits, and surface finish after stamping. These must be derived from alloy-specific work-hardening curves and grain structure data. Kravzik correlates alloy properties with tooling design parameters through its progressive die tooling process.
The table below compares the five processing parameters that most directly influence progressive die design: work-hardening exponent, blanking clearance, springback compensation, minimum bend radius, and plating adhesion performance.
Work-Hardening Rate & Formability Window
The work-hardening exponent (n-value) determines how uniformly an alloy distributes strain during bending. C11000 at n = 0.35 exhibits excellent formability, distributing strain across a wide bend zone.
Brass 260 at n = 0.25 and C19400 at n = 0.22 show moderate strain distribution. C51000 at n = 0.15 and C17200 at n = 0.10 localize strain at the bend apex, requiring larger bend radii and accurate tool radius control to prevent cracking.
The n-value translates directly to practical forming limits. C11000 accommodates a minimum bend radius of 0.5 times material thickness (0.5 t).
Brass 260 and C19400 require 1.0 t. C51000 demands 2.0 t. C17200 in solution-treated (AT) condition before stamping allows a 1.5 t minimum bend radius, but after age hardening the minimum bend radius increases to 3.0 t.
This is critical because C17200 terminals are typically stamped in the soft AT condition and then age-hardened to full strength — the stamping tooling must be designed for the AT condition bend limits, and the final part must not be bent again after heat treatment.
| Processing Parameter | C11000 (Annealed) | Brass 260 (Half-Hard) | C51000 (Spring) | C17200 (Sol.-Treated) | C19400 (Half-Hard) |
|---|---|---|---|---|---|
| Work-Hardening Exponent (n) | 0.35 | 0.25 | 0.15 | 0.10 | 0.22 |
| Blanking Clearance (% thickness) | 5-8% | 4-6% | 3-5% | 3-4% | 4-6% |
| Springback Angle (90 degree bend) | 2-4 degrees | 5-8 degrees | 8-15 degrees | 12-18 degrees | 5-7 degrees |
| Minimum Bend Radius (x thickness) | 0.5 t | 1.0 t | 2.0 t | 1.5 t (AT) / 3.0 t (aged) | 1.0 t |
| Plating Adhesion (cross-hatch) | 5B (excellent) | 4B | 3B (requires pre-clean) | 4B (requires Ni strike) | 4B |
Moisture absorption is not a factor for copper alloys, but surface oxidation begins within 24 hours of stamping for uncoated C11000 exposed to 50% RH ambient air. This oxide film reaches 20-30 nm thickness within 72 hours and degrades solderability and wire-bonding performance. C17200 forms a stable beryllium oxide passivation layer of 5-10 nm under the same conditions, which is why it tolerates longer shelf life between stamping and assembly.
[Data Anchor]: Blanking clearance for C17200 beryllium copper must be held at 3-4% of material thickness. Below 3%, secondary shear accelerates carbide punch wear to 5-8 micrometre per 100,000 strokes. C17200 in solution-treated condition allows 1.5 t minimum bend radius for stamping, but age-hardened strip requires 3.0 t minimum — a 2x increase that must be accounted for in tooling design if post-stamp heat treatment is specified.
Grain Structure & Edge Quality
Grain size controls the proportion of the burnish zone on the blanked edge. C11000 at ASTM grain size 6 (45 micrometre average diameter) produces a 35-40% burnish zone.
Brass 260 at ASTM grain size 7 (32 micrometre) yields 45-50% burnish. C19400 at ASTM grain size 7.5 (28 micrometre) produces 50-55% burnish.
C51000 at ASTM grain size 8 (22 micrometre) reaches 55-60% burnish. C17200 at ASTM grain size 9 (16 micrometre) produces 60-65% burnish, the highest among terminal copper alloys.
Burnish zone proportion directly affects contact resistance consistency when the blanked edge serves as the contact interface. C17200 with 60-65% burnish eliminates the need for secondary deburring to meet the 0.05 mm burr height maximum typical for connector terminal specifications. C11000 with 35-40% burnish requires post-stamp deburring or a secondary shaving station to achieve the same burr height limit.
Running clearance below 3% accelerates punch wear and produces secondary shear zones. Running above 8% increases burr height beyond 0.05 mm.
Surface oxidation post-stamping follows distinct kinetics per alloy. C11000 forms a cuprous oxide (Cu2O) film reaching 20-30 nm within 72 hours at 50% RH.
C17200 forms a stable beryllium oxide (BeO) passivation layer of 5-10 nm that prevents further oxidation. Brass 260 forms mixed Cu2O/ZnO at 15-25 nm thickness.
C51000 and C19400 form oxide layers of 5-15 nm. The thinner oxide films on C17200 and C51000 translate to longer shelf life between stamping and subsequent plating or assembly operations.
[Data Anchor]: C17200 beryllium copper at ASTM grain size 9 (16 micrometre) produces 60-65% burnish zone on blanked edges. This eliminates secondary deburring for terminals where the cut edge serves as the contact interface. C11000 at ASTM grain size 6 produces 35-40% burnish, requiring post-stamp deburring to meet 0.05 mm burr height maximum. The burnish zone difference between C11000 and C17200 represents a 25 percentage point edge quality gap that directly affects contact resistance consistency.
Manufacturability & Industrial Applications
Property data drives alloy selection. Material availability, press speed compatibility, and plating process integration drive production economics. The profile below maps each alloy to its manufacturing sweet spot and typical application domain.
Alloy Selection by Application Domain
C11000 copper in annealed condition suits high-current power terminals above 10 A with fewer than 1,000 mating cycles at room temperature. It runs at the highest press speeds, up to 400 strokes per minute on a 60-ton mechanical press with carbide tooling, because its low yield strength minimizes punch wear and its high ductility forgives small clearance variations.
Tooling maintenance intervals extend to 500,000 strokes between resharpening cycles. C11000 is not suitable for contact beam applications where the terminal must function as a spring member above 1.5 N contact force or at temperatures above 80 degree C.
C19400 at 65% IACS and 450 MPa tensile represents the optimal balance for automotive connector terminals carrying 5-15 A continuous current with 5,000-10,000 mating cycle requirements. Maximum press speed reaches 300 spm with D2 tool steel blanking punches and 250,000-stroke resharpening intervals. C19400 occupies the production sweet spot for powertrain control module terminals where conductivity and spring force must coexist.
C51000 phosphor bronze spring temper suits signal-level contacts requiring above 10,000 mating cycles at the expense of conductivity (15% IACS). Maximum press speed drops to 200 spm with tungsten carbide tooling and 150,000-stroke resharpening intervals. Brass 260 half-hard offers 28% IACS for mechanical grounding terminals where contact force retention matters more than current capacity.
C17200 beryllium copper serves aerospace, military, and high-reliability automotive connectors requiring the combination of 1380 MPa strength, 95% force retention at 150 degree C, and 200-hour salt spray resistance — at the cost of 8-12 week mill lead time and maximum press speed of 120 spm with specialized carbide tooling. Kravzik maintains full strip inventory of C11000, Brass 260, C51000, and C19400 in thicknesses from 0.15 mm to 1.5 mm for stamped terminal production.
For terminals requiring both conductivity and spring force, a bi-metal approach using C11000 body with C17200 contact beam resolves the conflict outside the stamping die via post-stamp assembly. This approach adds 15-25% per-part cost but avoids the material trade-off penalty.
[Data Anchor]: C19400 at 65% IACS conductivity and 450 MPa tensile strength represents the optimal balance for automotive connector terminals carrying 5-15 A continuous current with 5,000-10,000 mating cycle requirements. C11000 (101% IACS, 250 MPa) suits fewer than 1,000-cycle power terminals at room temperature only. C17200 (22% IACS, 1380 MPa) is reserved for applications above 50,000 mating cycles or operating temperatures above 125 degree C where force retention dominates cost considerations.
Plating & Finishing Compatibility
Plating adhesion strength varies significantly across the five substrate alloys. C11000 copper achieves a cross-hatch adhesion rating of 5B under ASTM D3359 for tin and silver electroplated finishes, provided the surface receives alkaline degreasing within 8 hours of stamping to prevent oxide film buildup beyond 10 nm. Brass 260 achieves 4B adhesion for tin plating due to zinc-atom surface segregation during electrodeposition, which creates a zinc-rich interlayer approximately 0.5 micrometre thick that reduces the effective tin-to-substrate bond area.
C19400 achieves 4B adhesion with standard pre-plate cleaning. C51000 rates 3B for as-stamped surfaces and requires an electrolytic alkaline pre-clean followed by a nickel strike layer of 0.5-1.0 micrometre before tin or silver top-coat deposition. C17200 requires a nickel strike layer of 1.0-2.0 micrometre due to the stable beryllium oxide surface film that resists conventional acid activation.
Without this strike layer, tin plating on C17200 delaminates during the 3% minimum elongation experienced at connector mating, exposing the substrate to galvanic corrosion.
Pre-plated strip eliminates post-stamp plating for C11000, Brass 260, and C19400 but is not recommended for C51000 or C17200 due to the risk of plating delamination at the tight bend radii these alloys require. See Kravzik’s in-house plating and finishing capabilities for process details.
[Data Anchor]: C17200 beryllium copper requires a nickel strike layer of 1.0-2.0 micrometre before tin or silver top-coat to achieve acceptable plating adhesion. Without this strike layer, cross-hatch adhesion falls below 3B and plating cracks propagate into the substrate during the 3% minimum elongation at connector mating. C51000 requires 0.5-1.0 micrometre nickel strike. C11000 achieves 5B adhesion with standard pre-plate cleaning alone.
Data to Spec
You selected C11000 copper six months ago because the conductivity spec demanded 100% IACS and the FEA model converged cleanly at 25 degree C ambient. What happens when that terminal operates inside a sealed engine-bay connector where ambient temperature reaches 95 degree C and the contact beam undergoes 50,000 micro-motion cycles over a 150,000-kilometre vehicle lifetime?
Yield strength drops 12% from the room-temperature value. Conductivity drops 3% from cold-work derating. Stress relaxation reduces contact normal force from 3.5 N to 2.1 N — below the 2.5 N minimum for tin-plated contacts per IEC 60512-2.
This triple failure mode is one that a single-alloy FEA model built on room-temperature data cannot predict.
Kravzik cross-references your terminal geometry, operating temperature profile, current requirement, and mating cycle target against the five-alloy dataset in this datasheet before the first strip enters the press. Our material engineering team returns a FEA-ready material card that includes thermal derating curves for yield strength, conductivity, and stress relaxation at your specific operating temperature — not at 25 degree C.
An in-house alloy inventory spanning C11000, Brass 260, C51000, and C19400 in thicknesses from 0.15 mm to 1.5 mm means the alloy that matches your thermal and mechanical boundary conditions is on the shelf, not on a mill lead-time schedule. For C17200 applications, mill partnership delivers 4-week expedited turnaround.
Still reconciling FEA results that diverge from dimensional reality on every prototype run? Send us your terminal specs for an alloy-matched DFM report. Kravzik returns a feasibility assessment with FEA-ready material cards (including thermal derating curves), bend compensation factors specific to your selected alloy and temper, and plating compatibility projections within 48 hours.
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