Manufacturers who need high-conductivity components face a difficult choice. Many materials that conduct electricity well are difficult to form. Those that form easily often lack the electrical performance required. Copper alloys like brass offer strength, but they sacrifice conductivity. C1100 pure copper solves this problem. With 99.9% copper content, it delivers the highest conductivity among commonly stamped metals. It also offers exceptional ductility. But stamping C1100 requires specialized knowledge. Its softness can lead to galling, surface scratches, and oxidation if handled incorrectly. This guide covers the properties, processes, and design considerations you need to stamp C1100 successfully. You will learn how to harness its conductivity without sacrificing quality.
What Makes C1100 Pure Copper Unique?
C1100 is not just another copper alloy. It is electrolytic tough pitch (ETP) copper with a minimum copper content of 99.9%. This high purity gives it properties that set it apart.
High Conductivity
C1100 achieves 98% to 100% IACS (International Annealed Copper Standard). That is the highest rating among stamped metals. For comparison, brass typically offers 28% to 60% IACS. In electrical applications, this difference matters. Higher conductivity means less energy loss as heat and better signal integrity.
Exceptional Ductility
In its soft temper (O), C1100 offers 45% to 50% elongation. It bends, draws, and forms into complex shapes without cracking. This ductility allows draw ratios up to 3:1 in deep drawing operations—much higher than harder copper alloys.
Natural Corrosion Resistance
C1100 develops a protective oxide layer when exposed to air. This layer resists atmospheric corrosion. However, it is less resistant to acids than brass. It performs well indoors and in mild outdoor environments.
Temper Options
C1100 is available in several tempers:
- O (annealed): Softest, most formable. Ideal for intricate stamping.
- H1 (lightly cold-worked): Slightly stronger, still formable. Good for parts needing minor strength.
- H2 to H4: Increasingly harder, less formable. Used when strength is the priority.
For most precision stamping, O temper is the preferred starting point.
How Is C1100 Copper Stamped?
Stamping C1100 requires different techniques than stamping steel or brass. The material is soft, ductile, and prone to galling. Each step must account for these traits.
Progressive Die Stamping
Progressive die stamping is ideal for high-volume parts like electrical terminals. A strip of copper moves through a series of stations. Each station performs a different operation: blanking, bending, piercing, or forming.
For C1100, annealing steps are often integrated into the process. After every three to four stations, the material is annealed to restore ductility. While C1100 work-hardens slowly compared to other metals, progressive forming still builds stress. Annealing keeps the material malleable through the entire process.
Blanking and Piercing
Blanking cuts the basic shape from the copper strip. Piercing cuts holes. For C1100, tool geometry matters greatly.
Use sharp, polished dies with 5% to 7% clearance. Too much clearance creates burrs. Too little clearance causes excessive force and tool wear. The cutting edges must be smooth. Any roughness will transfer to the part or cause the copper to stick.
Bending
C1100 bends easily, but surface cracking is a risk with tight radii. Use wide-radius punches with a minimum radius of 1× material thickness for O temper. For H1 temper, increase to 1.5× material thickness.
A 0.5 mm sheet in O temper needs at least a 0.5 mm bend radius. Going tighter increases the chance of cracking on the outside of the bend.
Deep Drawing
C1100’s ductility makes it excellent for deep drawing. Draw ratios up to 3:1 are achievable. But success depends on controlling the process.
Use slow press speeds, typically 8 to 12 strokes per minute. High speeds generate friction heat, which can degrade the surface and cause sticking. Heavy lubrication is essential. The lubricant must reduce friction without leaving residues that interfere with downstream processes like plating.
Annealing
Annealing restores ductility after forming. Heat C1100 to 400°C to 500°C for 1 to 2 hours, then air-cool. This process recrystallizes the grain structure, removing the effects of work hardening.
For C1100, annealing is needed less frequently than for harder alloys because it work-hardens slowly. But it is still critical after deep drawing or extensive forming.
What Are the Key Challenges in Stamping C1100?
C1100’s softness creates specific challenges. Understanding them is the first step to solving them.
Galling
Galling is the transfer of copper to the die surface. It happens when the material sticks and tears under pressure. Galling leaves rough spots on the part and wears down the tool.
Prevention methods:
- Polish dies to Ra ≤ 0.2 μm. Smooth surfaces reduce friction.
- Use anti-galling lubricants containing graphite or molybdenum disulfide.
- Clean dies every 500 strokes to remove copper buildup.
A manufacturer stamping electrical terminals once switched from standard dies to polished carbide dies with a special lubricant. Galling dropped by over 90%, and die life tripled.
Edge Cracking
Edge cracking happens when small cracks at the cut edge propagate during forming. It is more common in parts that are blanked first and then formed.
Prevention methods:
- Deburr blanks before forming. Sharp edges concentrate stress.
- Avoid sharp die corners. Use radii wherever possible.
- Anneal after blanking for parts with thin sections.
Surface Scratches
C1100’s soft surface scratches easily. Scratches are not just cosmetic. They can create stress risers and affect performance in high-reliability applications.
Prevention methods:
- Use plastic interleaving between stacked sheets.
- Handle parts with clean, padded tools.
- Post-stamping, clean with soft cloths, not abrasive pads.
Oxidation During Annealing
Annealing in air causes copper to oxidize. The surface turns dark or discolored. For parts that need a clean finish or will be plated, this is a problem.
Prevention:
- Anneal in an inert gas environment, such as nitrogen.
- Use vacuum furnaces for critical parts.
- For small-scale work, apply a protective coating before heating.
What Design Considerations Matter for C1100 Stamping?
Designing parts for C1100 stamping requires thinking about the material’s behavior.
Minimum Bend Radius
| Temper | Minimum Bend Radius |
|---|---|
| O | 1× material thickness |
| H1 | 1.5× material thickness |
| H2 and above | 2× material thickness or more |
These are guidelines. Complex bends may need larger radii.
Grain Direction
Copper sheet has a grain direction from rolling. Forming with the grain (bending parallel to the rolling direction) gives maximum ductility. Forming cross-grain increases the risk of edge cracking.
For critical bends, specify the grain direction on the drawing. For parts with bends in multiple directions, O temper is safer.
Lubrication
Lubricants must be non-reactive with copper. Mineral oils with anti-oxidants work well. Avoid lubricants containing sulfur, which can stain copper and affect conductivity.
Tolerances
C1100’s softness allows tight tolerances—down to ±0.01 mm for critical features. But springback must be accounted for. In bending, C1100 shows 1 to 2 degrees of springback. Over-bend accordingly.
Where Is C1100 Copper Stamping Used?
Electrical Connectors and Terminals
C1100’s high conductivity makes it the standard choice for electrical connections. Wiring harnesses, circuit breakers, and battery contacts all use stamped copper terminals. In electric vehicles, where currents are high and efficiency matters, C1100 is essential.
Heat Exchanger Components
Copper’s thermal conductivity is second only to silver. Stamped C1100 parts appear in radiators, cooling plates, and heat sinks. For electronics cooling, stamped copper fins and plates outperform aluminum.
RF Shielding
Electromagnetic interference (EMI) can disrupt sensitive electronics. C1100 provides effective RF shielding. Stamped copper shields are common in smartphones, medical devices, and aerospace equipment.
Automotive Electrical Systems
Modern cars have hundreds of electrical connections. C1100 stamped parts appear in sensors, relays, charging ports, and battery management systems. For electric vehicles, the shift to higher voltages makes conductivity even more critical.
What Post-Stamping Treatments Work for C1100?
Tin Plating
Tin plating improves solderability and corrosion resistance. It also prevents oxidation of the copper surface. Tin-plated copper terminals are standard in automotive and consumer electronics.
Passivation
Passivation with citric acid enhances the natural oxide layer. It improves corrosion resistance without affecting conductivity. Unlike passivation for stainless steel, citric acid passivation is safe and does not harm the copper.
Annealing
As noted, annealing restores ductility after forming. For parts that undergo multiple operations, intermediate annealing keeps the material workable.
Conclusion
C1100 pure copper offers an unmatched combination of conductivity and formability. Its 99.9% purity delivers the electrical performance that brass and other alloys cannot match. Its 45% to 50% elongation allows complex stamping operations that harder materials cannot handle.
But stamping C1100 requires expertise. Its softness demands polished dies, careful lubrication, and slow speeds. Its tendency to gall and scratch requires clean handling and proper tool design. Its need for annealing in inert atmospheres calls for specialized equipment.
When these factors are managed correctly, the results are components that perform reliably in demanding applications. Electrical terminals carry current without loss. Heat exchangers transfer thermal energy efficiently. RF shields protect sensitive electronics. And electric vehicles achieve the range and performance that consumers expect.
For manufacturers who need high-conductivity components, C1100 is not just an option. It is often the only choice that meets the performance requirements.
FAQ About Metal Stamping C1100 Pure Copper
Can C1100 be stamped into very thin parts?
Yes. C1100 can be stamped down to 0.1 mm thickness with proper tooling. Use O temper for thin-gauge work. Keep press speeds slow and blank holder pressure light to avoid wrinkling.
How does C1100 compare to brass for electrical parts?
C1100 offers about three times the conductivity of brass. It is also softer and more formable. Use C1100 for high-performance electrical contacts where conductivity is critical. Use brass for parts that need more strength or wear resistance.
What is the best temper for stamping C1100?
O (annealed) temper is best for complex stamping and deep drawing. It offers maximum ductility. H1 temper works for simpler parts that need slightly more strength.
Does C1100 need heat treatment after stamping?
C1100 work-hardens slowly, but after extensive forming it may need annealing to restore ductility. Heat to 400°C to 500°C for 1 to 2 hours in an inert atmosphere to prevent oxidation.
How do I prevent oxidation during annealing?
Anneal in a nitrogen atmosphere or use a vacuum furnace. Avoid annealing in air, which will discolor the surface and may affect subsequent plating or soldering.
Contact Yigu Technology for Custom Manufacturing
Stamping C1100 pure copper requires precision, clean handling, and deep material knowledge. At Yigu Technology, we specialize in custom copper stamping for electrical, automotive, and aerospace clients. We use polished carbide dies and inert gas annealing to maintain conductivity and surface quality. Our process controls ensure tight tolerances in connectors, terminals, and shielding parts. Whether you need high-volume production or complex prototypes, we have the capabilities to deliver. Contact us today to discuss your project.
