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3D Printing、MIM、HIP、Brazing、Spraying、Porous material、PM
CuSn3P7 copper–tin–phosphorus brazing alloy · Copper-based self-fluxing powder/paste
Low melting point · High wettability · Silver-free, environmentally friendly, specially formulated for brazing -150 mesh · Powder/ointment form
Process Advantages
Strong self-brazing capability
During brazing, phosphorus reduces oxide films and forms phosphate slag; therefore, copper and copper alloys typically do not require the addition of a separate flux, significantly simplifying the process.
Low melting point · Narrow melting range
Moderate melting point, reasonable melting range, excellent fluidity, reduced risk of overheating and deformation of the base material, and a wide process window.
High wettability · Dense weld seam
Tin effectively enhances the wetting and spreading on copper and brass, resulting in a dense, porosity-free brazed joint with excellent bonding strength.
Corrosion-resistant · Environmentally friendly and economical
The brazing alloy is resistant to moisture and weak acids and bases, contains no silver or cadmium, complies with RoHS, and offers lower costs than silver-based solders, delivering exceptional cost‑performance.
Product Real Shots & Microscopic Morphology
Powder SEM (-150 mesh)
Irregular/spherical particles with uniform particle size and excellent flowability.
Real photo of powdered brazing filler metal
Brown-gray powder, packaged in vacuum-sealed aluminum foil bags or plastic canisters.
Real-life photo of paste-type solder alloy
Syringe/plastic can packaging, ready-to-use, with adjustable viscosity.
CuSn3P7 copper–tin–phosphorus self-fluxing brazing filler metal
CuSn3P7 is a silver‑free copper‑based brazing alloy that, by incorporating tin and phosphorus, significantly lowers its melting point and imparts self‑fluxing characteristics. It enables flux‑free or low‑flux brazing of copper and copper alloys—including red copper, brass, and bronze—offering a wide process window, dense joints, and excellent corrosion resistance. The powdered filler metal is produced via non‑vacuum atomization, yielding uniform particle size and good flowability; it can be used directly in flame or induction brazing, or blended with an organic carrier to form a paste suitable for automated dispensing and screen printing. Compared with high‑silver brazing alloys, it delivers substantially lower costs while maintaining superior brazing performance, making it an ideal choice for applications such as refrigeration piping, electrical busbars, and automotive heat exchangers.
Chemical Composition (wt%, Preferred Grade)
| Grade | Cu | Sn | P | Ni | Solidus (°C) | Liquidus temperature (°C) |
|---|---|---|---|---|---|---|
| qCuP-3 (Featured) |
Bal. | 2-4 | 6-8 | — | 650 | 690 |
| qCuP-4 | Bal. | 6.5-7.5 | 6.4-7.2 | — | 650 | 700 |
| qCuP-1 | Bal. | — | 7.5-8.1 | — | 710 | 770 |
| qCuP-6 | Bal. | 7-8 | 4.8-5.8 | 0.4-1.2 | 620 | 670 |
| qCuP-11 | Bal. | 15.1-16.1 | 4.7-5.7 | 3.8-4.8 | 585 | 605 |
* We primarily promote the qCuP-3 (CuSn3P7) powder grade—150 mesh—and offer custom particle size options.
Solder Paste Specification (CuSn3P7)
| Grade | Alloy powder content (wt%) | Binder (wt%) | Solidus (°C) | Liquidus temperature (°C) | Recommended Process |
|---|---|---|---|---|---|
| CuSn3P7 solder paste | 80-90 | Margin | 650 | 690 | Automatic dispensing, screen printing, manual coating |
* Viscosity can be customized to suit the customer’s dispensing equipment; the carrier evaporates completely, leaving minimal residue.
Particle Size Specifications & Physical Properties (Powder Form)
| Particle size specification | Corresponding mesh count | D50 range (μm) | Loose packing density (g/cm³) | Tap density (g/cm³) | Flowability (s/50g) | Recommended Process |
|---|---|---|---|---|---|---|
| ★ -150 mesh | ≤106μm | 55-85 | ≥3.2 | ≥4.2 | ≤28 | Flame brazing, induction brazing, paste materials |
| -200 mesh | ≤75μm | 40-65 | ≥3.4 | ≥4.4 | ≤26 | Precision brazing, paste raw materials |
| -300 mesh | ≤48μm | 25-40 | ≥3.5 | ≥4.5 | ≤25 | Micro brazing, precision dispensing |
* -150 mesh is our standard specification; other particle sizes are available upon request. The powdered product can be blended with an organic carrier to produce solder paste.
CuSn3P7 Brazing Process Reference
| Base material combination | Recommended Brazing Temperature (°C) | Flux Usage | Joint characteristics |
|---|---|---|---|
| Red copper–red copper | 700-750 | Usually no flux is required (self-fluxing). | The brazed joint is dense, with excellent bonding strength. |
| Red copper–brass | 720-780 | FB102 may be used in small quantities. | Good wetting, with a full brazing angle. |
| Brass - Brass | 740-800 | It is recommended to use FB102. | The brazed joint is bright and exhibits high strength. |
| Copper-steel | 760-820 | FB102/borax is required. | Good compatibility; suitable for non-pressure-bearing components. |
* Red copper exhibits the best self‑brazing performance; for brass, it is recommended to use a small amount of flux. Induction brazing is best performed at higher temperatures, while flame brazing should be carried out with a neutral flame.
CuSn3P7 vs. conventional copper-phosphorus brazing alloys/silver brazing alloys
| Comparison item | CuSn3P7 | CuP14 (copper phosphide) | BAg silver brazing filler metal |
|---|---|---|---|
| Cost | Low | Extremely low | High |
| Brazing temperature (°C) | 690-900 | 850-900 | 700-800 |
| Self-brazing | Excellent | Excellent | None |
| Wettability (on brass) | Excellent (Sn improvement) | General | Excellent |
| Brazing seam toughness | Medium | Relatively brittle | Excellent |
CuSn3P7, while maintaining low cost and self‑brazing properties, significantly enhances wettability and brazed joint toughness through the addition of tin, making it a highly cost‑effective copper alloy brazing filler metal.
Typical application areas
Refrigeration equipment
Condenser, evaporator, copper piping for air conditioners/refrigerators, compressor fittings
Power and Electrical Engineering
Busbar, wire terminals, switch contacts, grounding terminals
Automobile manufacturing
Radiator, oil cooler, heater core, and pipe fittings
Plumbing hardware
Plumbing fittings, valves, copper fittings, and bathroom hardware
General Industry
Heat exchangers, copper components, and motor manufacturing
Electronics and electrical appliances
Conductive connections, relay contacts, busbars
Powdered brazing filler metal (-150 mesh)
- Can be directly sprinkled as powder or pressed into preformed solder tabs.
- Good fluidity, suitable for automatic powder feeding and flame brazing.
- It can be blended with other metal powders to formulate special compositions.
- Vacuum-sealed for long-term storage without oxidation.
Paste-type brazing filler metal (ready-to-use)
- No on-site mixing of powder and adhesive is required; simply open the container and use.
- Excellent thixotropy, precise dispensing/printing, and no sagging.
- The carrier volatilizes completely, leaving minimal residue.
- Viscosity is adjustable, making it compatible with various dispensing equipment and manual coating applications.
End-to-end testing capability
Each batch of CuSn3P7 powder and solder paste is tested for chemical composition (Cu, Sn, P), particle size distribution, oxygen content, flowability, and tapped density, with a Certificate of Analysis (COA) provided.
Packaging & Delivery
Powder packaging
Vacuum-sealed in a double-layer aluminum foil pouch (to prevent oxidation), with an outer iron or plastic drum.
Specifications: 1 kg, 5 kg, 10 kg, 25 kg per drum
Solder paste packaging
Syringes (10 cc/30 cc/50 cc) or plastic containers (100 g/500 g/1 kg)
Refrigerate; shelf life: 6 months.
Export packaging
Export orders are packed in wooden crates or pallets and reinforced to protect against moisture and impact.
Compatible with sea freight, air freight, and international express delivery.
Delivery time
Standard particle size in stock; ships within 2–5 days after order confirmation.
Solder paste customization or particle size fine-tuning: 3–7 days
Batch Traceability
For each batch, a sample is retained, and the COA report is shipped with the goods.
Supports third-party testing (e.g., SGS)
Free sample
Free samples are provided for process validation.
Small-batch samples; bulk supply upon quality confirmation.
Customized Services
Particle size customization, solder paste viscosity adjustment
Meets special operating conditions and equipment requirements
Technical Support
Providing brazing process parameters and solder paste application guidelines.
Assist in resolving issues encountered during use.
Inquire Now for Free Samples
Fill out the form on the right or contact us directly; we will provide product samples, technical data sheets, and price quotes to help you quickly complete your additive manufacturing process validation.
Address: No.39, Liandong Yougu lnd. Park, Bachelor Street,Changsha City,Hunan Province, China.
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Address: No.39, Liandong Yougu lnd. Park, Bachelor Street,Changsha City,Hunan Province, China.
