TECHNICAL HANDBOOK

Presentation

The technical data sheets created by the METACONCEPT Group are dedicated to tin-based alloys as well as hard brazing. Tin-based alloys are generally used to assemble metal parts at a temperature below 450°C. This brazing procedure is called“soft soldering”.

For all types of soldering it is necessary to use a flux (internal or external) which removes the layer of oxides and at the same time protects the parts and the solder from oxidation during the soldering process.

These alloys can be used for applications other than soft soldering, such as:

 

Brazing is an assembly method which is carried out between 600° and 850°C. It requires the use of a flux (internal or external) which removes the oxide layer whilst protecting the parts and the solder from oxidation during the brazing process (except copper/phosphorous solders which self-flux on the copper).

Characteristics

Soft soldering and other brazing methods

Techniques
Filler metal
Melting T°
Heating tools
Metals being assembled
Implementation
Solidity
Soft solderingTin-based alloy
140° – 450°
– Soldering iron
– Blow torch
– Solder bath
– Wave
– Induction
– Hot air
Almost all
Easy
Average
BrazingAlloys made from:
– Copper
– Silver
– Zinc
– Phosphorous
600° – 850°
Dual gas torchAll except :
– Zinc
– Lead
– Tin
Good
Good
Brass weldingBrass
(copper and zinc)
850° – 950°
Dual gas torch– Steel
– Stainless steel
– Cast iron
– Copper
Average
Good
WeldingThe same type of
parts being
assembled
1500° – 2000°
Electrival stationAll metals able to
withstand high
temperatures
Difficult
Good

Implementation

Main metals used for the implementation of alloys in soft soldering and brazing

Description
Symbol
Density
g/cm3
Melting
point
Properties
Uses
Antimony
Sb
6,68
630,5°
– ncreases the melting temperature
of the alloy
– Strengthens it
– Slightly improves its
wettability
– Slightly breakable metal
The metal’s use in batteries and Babbitt alloys represents half of its overall consumption.
Silver
Ag
10,5
962°
– Strengthens the alloy.
– Improves the “wettability”
– Used in small quantities
in the manufacture of tin-based
alloys.
Tin/silver alloys are primarily used in electronics and in the automotive sector. Silver-based alloys, for Cu/P-based brazing, are specifically used in plumbing; silver- based brazing is used for all types of work where the mechanical strength needs to be increased.
Bismuth
Bi
9,78
271,3°
– Very breakable metal
– As with antimony and gallium,
bismuth increases in volume
during solidification.
Often used for its fusibility and controllable dimensional change properties.
Copper
Cu
6,68
1084°
– Strengthens the alloy.
– Prevents “leeching”
(dissolution of the
parts’ copper into the solder
bath).
– Ductile metal with
particularly high
electrical and thermal
conductivity.
– Very resistant to corrosion
It is used in areas such as:
– Electrics
– Electronics
– Microprocessors
– Heat exchangers
– Building
– Pipes for soft soldering and
brazing
Tin
Sn
7,30
231,9°
– Malleable metal, fairly
ductile.
– Resistant to corrosion from
salt and fresh water, but may
be attacked by strong acids.
Used in practically all sectors where soft soldering is recommended.
Indium
In
7,31
156°
– Malleable metal, resistant to
corrosion.
– Soft metal like lead.
– Reduces the temperature of the alloy
Widely used in flat screens. It is used in:
– Avionics
– The nuclear industry
– Mechanics (bearings and
rollers)
– medecine
– Glass coatings
Phosphorous
P
2,40
NC
The higher the percentage of phosphorous in the Cu/P compound, the greater the fluidity of the alloy but also the more its mechanical characteristics are reduced.
Phosphorous-based brazing alloys are used in the cooling and air-conditioning sector and for any application where the assemblies must resist stresses resulting from expansion, shrinkage or vibrations.
Lead
Pb
11,35
327°
– Non-breakable
– Good value for money
– Soft metal
– Oxidises over time
Prohibitions of the use of lead in various applications are increasing because of its toxicity. Still commonly used in plumbing, roofing and zinc works.
Zinc
Zn
7,15
419°
Excellent joint stability (does not move over time) and solidity.
Rarely used in soft soldering. It is mainly used in the composition of brazing alloys.

Technical Glossary

 

Mechanical assembly:An assembly enabling two or more parts to be fixed together with a view to automating their operation.
Electrical assembly:An assembling combining and optimising the conduction between several parts with different properties.
Soldering:An action consisting of soldering with an alloy whose melting temperature is lower than that of the surfaces being soldered.
Brazing:An assembly operation carried out between 600 and 800°C.
Soft soldering:Generally tin based, it refers to assemblies created at temperatures generally lower than 450°C.
Bending:An operation consisting of adding a curve to a hollow or tubular part by injecting it with a fusible alloy which will be removed by raising the temperature.
Casting:An operation consisting of pouring the metal into the mould.
Degrees Celsius (°C):= °F – 32 (x 5 : 9)
Degrees Fahrenheit (°F):= °C (x 9 : 5) + 32
Electroplating:An operation, also known as surface treating, consisting of applying a thin layer of protective metal or alloy to a part using electrolysis.
Electroforming:The manufacture or reproduction of imprints produced by the electrolytic deposition of a metal on a mandrel and separated by demoulding.
Tinning:A technique consisting of applying a very thin layer of tin to a metal part.
Eutectic:The specific property of an alloy that goes from a solid state to a liquid state without passing through the mushy phase. This melting point of the eutectic alloy varies in accordance with the properties of the components.
Forming:An operation consisting of forming a part, in other words giving it a shaped, convex or concave appearance or creating an embossed design.
Laminating:An operation consisting of compressing the metal to turn it into sheets, strips, etc.
Moulding:An operation consisting of producing a part from a mould template.
Recycling:An operation consisting of collecting metallic scraps or residues from an alloy or a metal to give them a second life by refining them and removing impurities.
Slabbing:An operation consisting of stamping, cold forming or deforming a part outwards to create an embossed design.
Welding:An action consisting of permanently welding two parts together using an alloy whose melting temperature is the same as that of the parts being assembled.
Surfacing:An operation consisting of polishing the surface of a raw part.

Precautions for use

To prevent burns caused by the molten metal, it is advisable to wear a protective apron, shoes, gloves, helmet and glasses.
Do not smoke at the workstation.
The workstation must be well ventilated.
Wash your hands when leaving the workstation.

Comments:
Always use a flux suited to the intended use. Contact our technical department to ascertain which product is most suited to your application.

All of the information contained in this document is provided for informational purposes only and the METACONCEPT Group will not be held liable for it.