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Materials
C7701 nickel silver for shielding cans and contacts
C7701 is a copper-nickel-zinc alloy, often called nickel silver, standardized in JIS H 3130 for spring strip and equivalent to UNS C77000 and CuNi18Zn27. It solders without plating, stays bright and has good spring properties. We stamp C7701 1/2H from 0.15 mm coil for EMI shielding cans, frames and contacts.
Key specs at a glance
| Standard | JIS H 3130 (copper alloy strip for springs) |
|---|---|
| Equivalents | UNS C77000, EN CuNi18Zn27, GB BZn18-26 |
| In production at Sierxi | C7701 1/2H, 0.15 mm coil |
| Typical parts | Shielding cans and frames, spring contacts, terminals |
What is C7701 nickel silver?
Despite the name, nickel silver contains no silver. C7701 is roughly 55% copper, 18% nickel and the balance zinc. The nickel gives it a silver-white color, tarnish resistance and higher strength than brass, and the alloy keeps good spring properties in hard tempers.
| Element | Typical range (%) |
|---|---|
| Copper (Cu) | 54.0–58.0 |
| Nickel (Ni) | 16.5–19.5 |
| Zinc (Zn) | Remainder |
Typical mechanical properties by temper
| Temper | Tensile strength (N/mm²) | Hardness (HV) | Use |
|---|---|---|---|
| 1/2H | about 540–655 | about 150–210 | Shielding cans and frames with bends |
| H | about 630–735 | about 180–240 | Spring contacts with moderate bends |
| EH | about 705–805 | about 210–260 | Flat springs with gentle forms |
Physical properties
| Property | Typical value |
|---|---|
| Density | about 8.7 g/cm³ |
| Elastic modulus | about 125 GPa |
| Electrical conductivity | about 5–6% IACS |
| Magnetic | Non-magnetic |
Why C7701 is used for EMI shielding cans
- Solderability: it takes solder well without tin plating, which removes a plating step and its cost.
- Appearance: it resists tarnish and stays bright through storage and reflow.
- Formability in 1/2H: it bends cleanly into the side walls and snap features of a can or frame.
- Shielding: it provides effective shielding for typical board-level RF and digital noise. For low-frequency magnetic fields, steel-based materials are more effective.
C7701 compared with other shielding and contact materials
| Material | Solderability | Spring properties | Cost | Notes |
|---|---|---|---|---|
| C7701 nickel silver | Good, no plating | Good | Higher | Default for solder-mounted shields |
| SPCC + tin plating | Good when plated | Low | Lower | Plating needed; cut edges unplated |
| SUS304 | Poor | Good in hard tempers | Medium | Strong thin covers, clips |
| Phosphor bronze (C5191) | Good | Very good | Higher | Common for connector contacts |
Design rules for C7701 parts
- Specify the temper; 1/2H is the usual choice for cans and frames with 90° bends.
- Inside bend radius of at least about 0.5–1 × t in 1/2H; larger in H and EH.
- Keep solder flanges flat; coplanarity of the solder edge is what decides reflow yield.
- Mark pick-and-place pads and vent holes on the drawing.
- If the part is a contact, give force at deflection, not just geometry.
How to call out C7701 on a drawing
- Grade, temper and standard: for example “C7701R-1/2H (JIS H 3130)” or “CuNi18Zn27, R540”
- Thickness and tolerance; thin strip such as 0.15 mm is sensitive to thickness variation
- Plating, if any, and its thickness — or “no plating”
- Flatness or coplanarity of solder edges
- For contacts: force at deflection and cycle requirement
Frequently asked questions
Does nickel silver contain silver?
No. C7701 is copper, nickel and zinc. The name comes from its silver-white color.
Do C7701 shielding cans need tin plating?
Usually not. C7701 solders well bare. Plating can be added through our partners if your process requires it.
Can C7701 replace phosphor bronze for contacts?
Sometimes. C7701 is cheaper to solder and stays bright, while phosphor bronze generally has better spring and fatigue properties. Choose by contact force, cycle life and whether the part is soldered.
Is C7701 in scope of EU CBAM?
Copper alloys are not among the CBAM goods categories (iron and steel, aluminum, cement, fertilizers, hydrogen, electricity). Classification of the finished part is the importer’s decision.
Is C7701 harder to stamp than steel?
Not harder, but thin 0.15 mm strip needs tight die clearances to control burrs, and the bright surface marks easily. That is why we inspect flatness and burrs on first articles and on every lot.
What C7701 thickness do you stamp?
We currently run C7701 1/2H at 0.15 mm; our stamping range is 0.15–1.2 mm.
Related pages
Metal stamping
EMI shielding cans and frames
One-piece and two-piece board-level shields in nickel silver and steel.
Metal stamping
Stamped spring clips and spring contacts
Flat springs, grounding fingers and battery contacts.
Metal stamping
Stamped terminals and electrical contacts
Copper-alloy terminals, lugs and contacts, loose or on carrier strip.
Materials
JIS, ASTM and GB material equivalents
Equivalent grades for SPCC, SGCC, SUS304, A5052 and C7701 across JIS, ASTM/UNS, EN and Chinese GB standards, for stamping and sheet metal.