Patent ID: 8920938

Claim:
A flat product made of a metal material for whose surface, over a basic area of at least 0.8×0.8 mm 2 , after removing a possible slope in the basic area's topography, filtering out high frequency portions by means of a Gaussian low-pass filter (λs=10 μm) and determining a frequency distribution of the height values with a class size of 0.1 μm, has: a) the frequency distribution of the height values has two pronounced maxima, which equate to correspondingly pronounced peak and valley levels of the surface; b) when just those topography regions, which have a slope of 5° at the most in relation to the basic area (horizontal) are observed, the frequency distribution of the height values resolve into at least two local main maxima, a peak main maximum and a valley main maximum; which local main maxima are substantially normally distributed with the peak main maximum having a standard deviation of 2σ≦2 μm and the valley main maximum having a standard deviation of 2σ≦1 μm; c) frequency of peaks is greater than frequency of valleys; d) the peak main maximum is also an absolute maximum; e) a difference between the peak main maximum and the valley main maximum is 1 μm-5 μm; and f) on a level, which lies exactly midway between the peak main maximum and the valley main maximum, the half width of the valleys is 40 μm-100 μm and the half width of the peaks is 40 μm-100 μm, wherein at least 99.99% of topography measurement points possess a minimum distance to the edge of the valleys or peaks of 40 μm-100 μm.