BCuP-2 to BCuP-5 powder for paste, rings and preforms. Self-fluxing on copper, silver-bearing options for brass and wide gaps. AWS A5.8 certified lots.
QUICK ANSWER
BCuP powder is a copper-phosphorus brazing alloy (typically Cu-7P, or silver-bearing BCuP-5 with 15% Ag) that self-fluxes on copper and joins copper-to-copper and copper-to-brass without additional flux. Melting at 650-800 °C depending on grade, it is the standard filler for HVAC/R copper tube joining, electrical busbar brazing, and heat exchanger production — the highest-volume brazing alloy family in the world.
Phosphorus does two jobs in these alloys: it depresses the copper melting point into a practical brazing range, and it reduces copper oxide on the joint surface, giving self-fluxing behavior on copper that eliminates flux cost and flux-residue corrosion. Powder and paste forms serve automated dispensing in refrigeration line-set production and preplaced-ring manufacture, where dosing accuracy determines joint quality at line speeds. Note: phosphorus-bearing alloys must never be used on nickel-bearing or ferrous alloys, where they form brittle phosphides.
MATERIAL DATA
Lot-level controls focus on the chemistry, particle characteristics, and process values that influence manufacturing consistency and finished-part performance.
| Element | Content | Performance Role |
|---|---|---|
| Copper (Cu) | Balance (86-93 wt%) | Conductive, ductile base matching copper tube metallurgy |
| Phosphorus (P) | 6.8-7.5 wt% (BCuP-2) | Melting depressant and self-fluxing agent on copper |
| Silver (Ag) | 0-15 wt% (grade dependent) | Improves flow, ductility, and gap-filling in premium grades |
| Tin (Sn) | 0-6 wt% (some grades) | Further lowers melting point and improves wetting |
| Others | < 0.15 wt% total | Impurity limits per AWS A5.8 |
Final limits can be aligned with the agreed purchase specification.
APPLICATIONS
HVAC and refrigeration is the defining market: copper tube joints in air conditioners, heat pumps, refrigeration line sets, and heat exchangers are brazed by the billions annually with copper-phosphorus alloys. Automated production lines use paste-dispensed or preplaced-ring BCuP on return bends and manifold assemblies, where the self-fluxing behavior keeps cycle times short and joints leak-tight for the unit's service life. Powder buyers in this market are paste formulators and ring manufacturers who buy on particle size consistency and phosphorus control.
Electrical and plumbing markets follow: busbar and switchgear joints use BCuP where conductivity matters; copper plumbing fittings in commercial buildings are brazed with silver-bearing grades for their better gap-filling on field-fit joints. The silver-bearing grades (BCuP-5, BCuP-6) also serve jewelry and instrument manufacture where their lower melting range protects heat-sensitive assemblies.
BRAZING FILLER & SOLDER POWDERS
CUSTOM SUPPLY
We supply the full BCuP range in powder form for paste and preform production: BCuP-2 for flux-free copper joining, silver-bearing grades for improved flow on brass and wider gaps. Custom phosphorus levels, size cuts for ring pressing, and matched paste-formulation support are available. Export note for silver-bearing grades: China's silver export is administered under quota and state-trading rules; our silver-bearing brazing powders are exported as manufactured alloy products with the required declarations, and we confirm documentation at order placement.
We supply the full BCuP range in powder form for paste and preform production: BCuP-2 for flux-free copper joining, silver-bearing grades for improved flow on brass and wider gaps.
Custom phosphorus levels, size cuts for ring pressing, and matched paste-formulation support are available.
Export note for silver-bearing grades: China's silver export is administered under quota and state-trading rules; our silver-bearing brazing powders are exported as manufactured alloy products with the required declarations, and we confirm documentation at order placement.
MATERIAL COMPARISON
| Comparison Point | This Product | BCuP-5 (15% Ag) |
|---|---|---|
| Melting range | 707-793 °C | 643-802 °C — wider plastic range |
| Gap filling | Close-fit joints | Excellent on wider, uneven gaps |
| Ductility | Moderate — P-rich phases | High — silver plasticizes the alloy |
| Cost | Low | 2-3x (silver content) |
| Flux on brass | Required | Required |
| Best use | Production-line copper tube | Field joints, brass, vibration service |
TECHNICAL FAQ
Need a different chemistry, particle range, or processing route? Our material team can review the requirement and supply window.
Phosphorus reacts with iron and nickel to form hard, brittle phosphide layers along the joint interface. The joint may look acceptable but fails under vibration or thermal cycling — use silver-bearing BAg alloys or nickel fillers for ferrous joints instead.
No — the phosphorus self-fluxes on copper and copper-rich alloys. On brass and bronze, zinc and tin oxides are not reduced by phosphorus, so an external flux is required.
BCuP-2 or the tin-modified variants for close-fit production joints; move to BCuP-5/6 when joint fit-up varies or brass components enter the assembly. We supply trial quantities for line qualification.
Silver metal export from China is quota-administered, but manufactured brazing alloys ship as finished products with composition declarations. Lead times remain normal; we handle the export documentation.
Typically -100/+325 mesh with controlled apparent density for consistent press-fill. Tell us your ring geometry and we match the powder cut and flow characteristics.
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