1. General

The usability of metallic materials, even after a long period of time, depends on the one hand on the storage conditions, but also on the requirements during further processing of the material by the customer.

Soldering processes in which good solder wettability is required must be considered as more critical than other applications in which e.g. color properties or corrosion effects play a role.

In principle, the mechanical and electrical properties of metal strip are not affected by environmental influences.

Surface effects such as oxidation, discoloration and corrosion, on the other hand, are sensitive and require precautions in order to avoid them.

Coatings, applied galvanically, electrolytically, or by hot- dip tinning, are critical and temperature sensitive. They can - depending on the layer structure - change their composition and thus their properties. This affects, for example, the mechanical wear resistance, the electrical (transition) resistance and the coefficient of friction.

Kemper AIP Metals will have the original surface appearance ensured for up to 150 days (5 months) ex-mill date. After this period, Kemper AIP Metals reserves the right not to accept the quality claims for stains and oxidation.

2. Optimal storage conditions

To avoid oxidation, discoloration and corrosion, we recommend the following storage conditions:

Max temperature fluctuation within a day: 46.4° F
Minimum temperature: 50° F
Maximum temperature: 86° F
Average temperature during winter: 59° F (reference value)
Average temperature during summer: 75.2° F (reference value)
Maximum fluctuation in relative humidity: 20%
Maximum relative humidity: 75%
Average relative humidity during winter: 50% (guide value)
Average relative humidity during summer: 60% (guide value)
Implementation of the “First In First Out” principle
The package must be stored in its original, unopened and undamaged condition.

Storage times of more than 5 months should be avoided if possible. Manufacturers of substances for surface passivation for bare and coated surfaces, available at the market, usually show an effective duration of the surface protection of up to 5 months.

Kemper AIP Metals will have the original surface appearance ensured for up to 150 days (5 months) ex-mill date. After this period, Kemper AIP Metals reserves the right not to accept the quality claims for stains and oxidation.

3. Measures during strip production to protect against oxidation, discoloration and corrosion

3.1 Oiling

As standard, the oiling of the surface offers a certain degree of protection against oxidation and corrosion.

Discoloration can be caused by residues.

This discoloration can easily be removed in the following processes, e.g. by alkaline or electrolytical degreasing.

3.2 Passivation

Bare copper alloy surfaces a passivation ("Benzotriazole", BTA) can be applied after degreasing. The protection is long lasting (5 months).

However, since the surface is very dry, the risk of fretting corrosion is increased.

Typically, when this surface treatment is used, special moisture-proof packaging is applied to the metal strip.

Both in combination, BTA treatment and moisture protection packaging represent the optimal protection for copper alloy strips.

3.3 Hot dip tinning

Hot dip tinned strip surfaces generally do not require any further measures to prevent corrosion.

The tin layer forms a very thin, dense oxide skin that protects the underlying material from further attack by atmospheric oxygen.

Even uncoated stamped edges and imperfections are protected by the anode principle. To avoid fretting corrosion, oiling is recommended in any case.