 | Making Permanent Joints - Course: Basic skills and knowledge of electrical engineering. Trainees' handbook of lessons (Institut für Berufliche Entwicklung, 19 p.) |
 |  | 3. Soldered Joints |
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3.1. Accessories
Soldering fluxes
Soldering fluxes are non-metallic materials preparing the metal surface for soldering. They are important for faultless soldering.
Soldering fluxes have the following properties:
- Removal of unwanted layers from the metal surface.
- Complete moistening of the metal surface to facilitate flowing of the solder.
- Protection of the cleaned metal surface against oxidation.
Soldering fluxes and their behaviour and use:
|
Soldering fluid |
aggressive |
for thick multi-core conductors |
|
Soldering paste |
aggressive |
for thick multi-core conductors or heavily or oxidized conductors |
|
Soldering tincture |
conditionally aggressive |
for fine soldering |
|
Colophony (rosin), solid or dissolved in spirit |
non-aggressive |
for manual fine soldering |
Solders
Solders are metals with a lower melting point than that of the metals to be joined. Common solders are tin and lead based.
Depending on their use, they are available in different forms:
- Bar solder for soldering baths.
- Thread type solder for manual soldering.
- Strip solder with flux for manual soldering.
- Friction solder for manual soldering of aluminium.
Cleaners
Fluxes, such as soldering tincture or soldering paste, become detrimental to the properties of soldered joints in the course of time. Therefore, it is necessary to remove flux residues after soldering. For cleaning of the soldered joints we use
- spirit or
- naphtha.
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