• 24. April 2020

Why are copper and copper alloy strips hot-dip-tinned?

This question arises immediately if the "noble" copper strip is coated by base tin. But there are 3 good reasons for this:

Number 1:
Tin is an excellent corrosion protection for copper strips, because its base character ensures that tin is preferentially attacked by various liquid and gaseous media. The copper strip underneath is protected against corrosion.  Depending on the conditions, the applied tin layer is „sacrificed“ over a long period of time.

Number 2:
In addition to good electrical conductivity, tin has very good forming properties, which is also referred to in technical terms as very good ductility.  
Conductivity and ductility are the essential properties that are of particular importance for connector applications.

Number 3:
The third essential parameter is the good wear resistance of the tin layer, which must ensure that the electrical connection is plugged in and pulled out at least 10 times. The formation of an intermetallic phase, which is formed directly when copper strip comes into contact with molten tin, is helpful in reaching this user requirement.  Compared to tin, this phase formation is very hard and an essential characteristic of hot-dip tinning, since it occurs directly and without additional treatment.

Due to the high ductility of the tin, when the tab and receptable are plugged in, the contact point (s) of the system is embedded with tin, which is the main reason for the good contacting, as well as the good corrosion resistance, since corrosion media do not have direct access to the contact point.

These essential technological properties, combined with the comparatively high productivity of a hot-dip tinning system, even with thicker layers, make the process of hot-tinning copper strips an ideal and preferred material combination for connector applications. The KMD Group, Stolberg plant has almost 40 years of experience and operates one of the most efficient systems for hot-dip tinned strips worldwide.

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