Purity 99.9% · CAS 7440-50-8 · Cu
Copper Powder 99.9% (3N) — powder metallurgy grade
Powder metallurgy, conductive fillers, MIM
Overview
Gas- or water-atomised copper at three-nines purity with controlled oxygen and a narrow particle size distribution. The workhorse grade for pressed-and-sintered parts and for conductive polymer fillers.
Typical trace impurities
| Impurity | Typical max |
|---|---|
| O (oxygen) | ≤ 2000 ppm |
| Fe | ≤ 100 ppm |
| Pb | ≤ 50 ppm |
| Ni | ≤ 50 ppm |
Indicative values. The certificate of analysis for your lot is the binding document.
Where this grade is used
- ▪Powder metallurgy part makers
- ▪Metal injection moulding feedstock producers
- ▪Conductive and EMI-shielding compound formulators
- ▪Diamond tool and metal-bond segment producers
Common forms
Spherical, irregular, dendritic
Specification at a glance
| Material | Copper Powder (Cu) |
|---|---|
| Purity | 99.9% (3N), metals basis |
| CAS | 7440-50-8 |
| Production route | Water or gas atomisation from refined cathode copper |
| Available forms | Spherical, irregular, dendritic |
| Analysis method | ICP-OES assay plus oxygen determination |
| Documentation | Certificate of analysis per lot, RoHS and REACH statements, country of origin |
| Typical packaging | 50 g argon-sealed jar · 500 g · 5 kg · Bulk drums |
What 99.9% (3N) actually means
3N is shorthand for 99.9% purity on a metals basis: at most 0.1% of the material, by weight, is something other than Cu. The metals-basis convention excludes dissolved gases and, for powders, surface oxygen — which is why oxygen is quoted separately in the trace table below.
Two lots at the same nominal purity are not interchangeable if the residual elements differ. For this grade the limiting element is typically O (oxygen) at ≤ 2000 ppm. What matters is which impurities your process is sensitive to — judge a lot on its full trace analysis, not on the headline number.
Choosing 3N versus the neighbouring grades
Coming from 99% (2N): the step up buys you tighter trace control for powder metallurgy, conductive fillers, mim. If your process tolerates the residuals of 2N, the lower grade remains the more economical and more widely available choice.
Going up to 99.99% (4N) is worth it when additive manufacturing, conductive inks describes your application; expect a materially higher cost per kilo and scarcer availability for a difference few processes can detect otherwise.
When in doubt, qualify both adjacent grades on a sample and run your own incoming inspection before committing a process to either.
Quality control and traceability
Copper Powder at 99.9% is normally released against a lot-specific certificate of analysis stating the assay, the trace elements measured and the method used (ICP-OES assay plus oxygen determination). Well-run lots stay traceable from the refinery batch through to the container that reaches the laboratory.
- ▪A retained sample per lot, so a later question can be re-tested against the original material
- ▪Independent third-party verification, used when the assay is contractually critical
- ▪Incoming inspection on the receiving side — the certificate states the method, not the result you will measure
Handling, storage and shipping
- ▪Fine copper powder oxidises at the surface; keep containers sealed and open them under inert gas or dry air for grades from 5N upward.
- ▪Sub-45 µm cuts are classified as a combustible dust — ground equipment, avoid dust clouds and follow ATEX or NFPA 484 practice on site.
- ▪Store between 5 °C and 30 °C at low humidity, away from ammonia, acids and sulphur compounds.
Frequently asked questions
Common questions from buyers specifying copper powder at 99.9%.
- Is 99.9% copper powder the right grade for my application?
- It is the usual choice for powder metallurgy, conductive fillers, mim. Below it, 99% (2N) covers less demanding work at lower cost. Above it, 99.99% (4N) is reserved for additive manufacturing, conductive inks.
- What does the 3N designation mean?
- The N notation counts the nines in the assay: 3N equals 99.9% Cu on a metals basis, with the balance made up of the trace elements listed in the analysis table.
- Which impurities are measured and reported?
- ICP-OES assay plus oxygen determination is used, and a certificate of analysis reports each element in the table above, starting with O (oxygen) at ≤ 2000 ppm. The scope of a scan can be widened to further elements when a process is sensitive to one in particular.
- How is this grade normally packed?
- 50 g argon-sealed jar, 500 g, 5 kg, Bulk drums. Sub-45 µm cuts are classified as a combustible dust — ground equipment, avoid dust clouds and follow ATEX or NFPA 484 practice on site.
- Which forms is 99.9% copper powder available in?
- Commonly: spherical, irregular, dendritic. The form is often a bigger practical constraint than the assay itself, because the last processing step has to preserve the purity already achieved.