Two mechanisms drive material choice, and confusing them is the most common selection error.
| Mechanism | Depends on | Frequency band | Material direction |
|---|---|---|---|
| Electric field (reflection) | Conductivity | GHz range — WiFi, 5G, Bluetooth | High conductivity: copper, tin-plated copper, brass |
| Magnetic field (absorption) | Permeability | Tens of kHz to a few MHz | High nickel: nickel silver, permalloy, Ni-Fe alloys |
"More nickel means better shielding" is not true. Nickel silver dominates phone and WiFi module cans because it balances solderability, corrosion resistance, formability and cost — not because of its nickel content. Genuine magnetic shielding near transformers and inductors is where high-nickel or permalloy is actually needed.
| Alloy | Type | Conductivity* | Relative cost | Best for |
|---|---|---|---|---|
| C7521 | Nickel silver (CuNiZn) | ~6–9% IACS | Baseline | Mainstream cans, decorative parts, antennas |
| C7701 | Nickel silver (high Ni) | ~5–7% IACS | Slightly higher | Cans needing higher corrosion and strength |
| ZSNH / KU400 | Zinc-tin-nickel | ~5–8% IACS | 20–30% lower | Mid-range cans and decorative substitutes |
| C2680 brass | Cu-Zn | ~27% IACS | Low | High-frequency shields, cost-first shields |
| SPTE | Tin-plated steel | ~9–12% IACS (surface) | Low | Low-frequency shielding |
| C17200 | Beryllium copper | ~22–28% IACS | 3–5× higher | Combined shield and spring fingers |
* Industry-typical. Final shielding effectiveness is dominated by structure — gap size, number and placement of grounding points, cavity depth. Material is one variable among several.
| Item | Specification | Typical use |
|---|---|---|
| Conductive cloth | Cu-Ni plated polyester fabric | Can gap wrapping, cable shielding |
| Conductive cloth tape | Conductive adhesive, die-cuttable | Grounding, cavity sealing |
| Single-sided Cu foil tape | Copper foil, single conductive adhesive | Local shielding, PCB grounding |
| Double-sided Cu foil tape | Conductive adhesive both faces | Interlayer conduction, shield fixing |
| Aluminium foil tape | Al foil, conductive adhesive | Lightweight, cost-first shielding |
A can must be solderable, deep-drawable, effective and affordable at once. Stainless steel conducts at 2–3% IACS with poor solderability and plateability — and since the can is soldered to the PCB for grounding, that alone rules it out.
Nickel silver C7521/C7701 gives ~6–9% IACS with 10–18% nickel for some magnetic shielding, plus corrosion resistance, deep drawability and a white appearance at a fraction of beryllium or titanium copper cost. Note that structural design — gaps, grounding points, cavity depth — drives effectiveness more than the alloy does.
Yes for mid-range cans and decorative parts, typically 20–30% cheaper (varies by temper and gauge; confirm against current quotation). ZSNH, ZN36, KU360, KU400 and KU570 were developed specifically to replace nickel silver: similar colour, density, strength and formability, with conductivity in the same order of magnitude.
Three gaps remain: slightly lower corrosion resistance, so long-term reliability in salt spray or high humidity trails C7521; a narrower soldering window requiring reflow re-qualification; and the fact that Japanese and automotive electronics customers specify C7521 directly, making substitution a formal change-control process. Supply samples for salt-spray and solderability validation before quoting as a drop-in.
Depends on the design. Contact areas that solder to the PCB usually need tin plating for solderability; the rest of the surface often does not. Plating only the functional zones is called selective or spot plating and cuts tin or precious metal consumption substantially.
If the whole can is soldered or must conduct across its full area, overall plating applies. Before selective or spot plating, the stamping pitch, feed direction and plating position tolerance must all be fixed — change any one and the plating mask must be rebuilt.
Body material and accessories from one supplier. Small-lot sampling with salt-spray and solderability validation available.