Handy & Harman/Lucas-Milhaupt Brazing Filler Metals

Silver Copper Phosphorus Alloys

and

Copper Phosphorus Alloys

This table is intended to cover only a few typical applications of the most frequently used brazing filler metals. For special brazing problems, contact our Technical Services Department.

Note: The Sil-Fos and Fos-Flo filler metals are for use with copper and copper alloy base metals. Do not use these materials to join ferrous materials as brittle phosphate compounds will be formed at the interface. The Sil-Fos and Fos-Flo filler metals have a unique characteristic called the "Flow Point". The "Flow Point" is defined as the temperature at which the filler metal is fluid enough to capillary through a joint even though not completely liquid (i.e. above the liquidus temperature).

Filler Metal name: Sil-Fos 18
Typical Applications: A ternary eutectic filler metal for joints where good fit-up can be maintained and low melting point is of prime importance. Clearance: .001" to .003" (.025mm to .127mm). Very fast flo.
Solidus: 1190'F/645'C
Liquidus: 1190'F/645'C
Max. Recom. Brazing Temp. 'F: 1300
Nominal Composition,%: 18Ag 74.75Cu 7.25P
Joint Color as Brazed: Gray
Density Troy lb./cu in: .293
Electrical Characteristics
  • Conduct. % IACS: 5.9
  • Resistivity microhm-cm: 29.4

Filler Metal name: Sil-Fos
Typical Applications: For use where close fit-ups cannot be maintained and joint ductility is important. Recommended joint clearance: .002" to .005" (.051mm to .127mm). Slow flow. The only phos/copper silver filler metal available in strip or sheet form.
Solidus: 1190'F/645'C
Liquidus: 1475'F/800'C Flow Point: 1300'F/705'C
Max. Recom. Brazing Temp. 'F: 1500
Nominal Composition,%: 15Ag 80Cu 5P
Joint Color as Brazed: Gray
Density Troy lb./cu in: .305
Electrical Characteristics
  • Conduct. % IACS: 9.9
  • Resistivity microhm-cm: 17.4

Filler Metal name: Sil-Fos 6
Typical Applications: A very fluid filler metal for close fit-up work. Low melting range makes it ideal where temperature is a factor. Recommended joint clearance: .001" to .003" (.025mm to .076mm). Fast flow. Lowest melt and flow in the minimum silver class.
Solidus: 1190'F/645'C
Liquidus: 1325'F/720'C Flow Point: 1275'F/690'C
Max. Recom. Brazing Temp. 'F: 1450
Nominal Composition,%: 6Ag 86.75 7.25P
Joint Color as Brazed: Gray
Density Troy lb./cu in: .284
Electrical Characteristics
  • Conduct. % IACS: 7.9
  • Resistivity microhm-cm: 21.9

Filler Metal name: Sil-Fos 6M
Typical Applications: Recommended for use where close fit-up cannot be maintained. Has the ability to fill gaps and form fillets without affecting joint strength. Recommended joint clearance: .002" to .005" (.051mm to .127mm). Slow flow.
Solidus: 1190'F/645'C
Liquidus: 1495'F/815'C Flow Point: 1325'F/720'C
Max. Recom. Brazing Temp. 'F: 1500
Nominal Composition,%: 5Ag 89Cu 6P
Joint Color as Brazed: Gray
Density Troy lb./cu in: .294
Electrical Characteristics
  • Conduct. % IACS: 9.6
  • Resistivity microhm-cm: 18.1

Filler Metal name: Sil-Fos 5
Typical Applications: Designed primarily for those applications where close fit-ups cannot be maintained. It has ability to fill gaps and form fillets without adversely affecting joint strength. Recommended joint clearance: .002" to .005" (.051mm to .127mm). Slow flow.
Solidus: 1190'F/645'C
Liquidus: 1495'F/815'C Flow Point: 1325'F/720'C
Max. Recom. Brazing Temp. 'F: 1500
Nominal Composition,%: 5Ag 89Cu 6P
Joint Color as Brazed: Gray
Density lb./cu in: .294
Electrical Characteristics
  • Conduct. % IACS: 9.6
  • Resistivity microhm-cm: 18.1

Filler Metal name: Sil-Fos 2
Typical Applications: A filler metal with comparable characteristics to Fos-Flo 7. Recommended joint clearance: .001" to .005" (.025mm to .127mm). Medium flow.
Solidus: 1190'F/645'C
Liquidus: 1450'F/875'C Flow Point: 1325'F/720'C
Max. Recom. Brazing Temp. 'F: 1500
Nominal Composition,%: 2Ag 91Cu 7P
Joint Color as Brazed: Gray
Density Troy lb./cu in: .289
Electrical Characteristics
  • Conduct. % IACS: 5.5
  • Resistivity microhm-cm: 31.5

Filler Metal name: Sil-Fos 2M
Typical Applications: Has ability to fill moderate gaps in poorly fitted joints. More ductile that fos-Flo 7 or Sil-Fos 2. Intended for use on copper tube headers and similar applications where a sleeve fit is not practical. Recommended joint clearance: .002" to .005" (.051mm to .127mm). Slow flow.
Solidus: 1190'F/645'C
Liquidus: 1495'F/815'C Flow Point: 1350'F/730'C
Max. Recom. Brazing Temp. 'F: 1550
Nominal Composition,%: 2Ag 91Cu 5P
Joint Color as Brazed: Gray
Density Troy lb./cu in: .2992
Electrical Characteristics
  • Conduct. % IACS: 7.5
  • Resistivity microhm-cm: 22.9

Filler Metal name: Fos-Flo 7
Typical Applications: An economical, very fluid medium temperature filler metal for use with copper, brass and bronze. Withstands moderate vibration, Recommended joint clearance: .002" to .005" (.051mm to .127mm). Fast flow.
Solidus: 1310'F/710'C
Liquidus: 1460'F/795'C Flow Point: 1350'F/730'C
Max. Recom. Brazing Temp. 'F: 1550
Nominal Composition,%:92.75Cu 7.25P
Joint Color as Brazed: Gray
Density Troy lb./cu in: .289
Electrical Characteristics
  • Conduct. % IACS: 7.5
  • Resistivity microhm-cm: 23.2

Filler Metal name: Fos-Flo 6
Typical Applications: An economical filler metal with a wide melting range and moderate flow. For use where close fit-ups cannot be maintained and ductility is important. Recommended joint clearance is .003" to .005" (.076mm to .127mm).
Solidus: 1310'F/710'C
Liquidus: 1570'F/854'C Flow Point: 1375'F/746'C
Max. Recom. Brazing Temp. 'F: 1600
Nominal Composition,%: 93.85Cu 6.15P
Joint Color as Brazed: Gray
Density lb./cu in: .293
Electrical Characteristics
  • Conduct. % IACS: 7.2
  • Resistivity microhm-cm: 24.1