SCHOTT Borofloat® 33 / Nexterion® Glass B Flatness and Surface Quality

SCHOTT Borofloat® 33 / Nexterion® Glass B

Borofloat® 33 is a flat, borosilicate glass

Borofloat® 33 is manufactured using the “microfloat” method

The production method produces virtually flawless flat glass and a mirror-like surface quality

Many Parameters Influence Glass Sheet “Flatness”

Surface Flatness is the deviation for a plano surface Warp is the difference between the maximum and minimum deviations of the median

surface relative to the backside reference plane. Warp is like the wavy deformation seen in potato chips.

Bow is the measure of how concave or convex the deformation of the median surface of the glass sheet at the center point, independent of any thickness variations. The easy way to visualize Bow is if you think of a bowl turned either upside down or right side up on a flat surface (convex or concave).

Total Thickness Variation (TTV) represents the difference between the minimum and maximum thickness measured on the sheet of glass.

Thickness Tolerance (inter-slide) The production of large flat sheets of glass yields variances in thickness. Thickness will vary depending on sheet size and where on the sheet the measurement is made. In order to accommodate this fact SCHOTT uses a nominal tolerance value

Thickness deviation (intra-slide) This is the thickness differences between slides Surface Roughness Smoothness: RA (average roughness) or RMS (root mean

squared) is a measure of the texture of a surface.

Bow and Warp

Total Thickness Variation (TTV)

“Flatness” of Nexterion® Glass B Slides

SCHOTT Nexterion® defines “flatness” as the accumulated overall possible thickness deviation

This includes warp, intra-slide thickness deviation, and inter-slide thickness tolerance

Thickness deviation intra-slide Thickness tolerance inter-slide  

Nexterion® slides have a maximum total “flatness” deviation of ≤ 25 µm for these three factors combined

Measurement of individual Glass B Slide Flatness using Interferrometry

ZYGO's VeriFire™ XP/D Laser Fizeau mechanical phase-shifting interferometer

Flatness of Nexterion® Glass B Slides

  

The typical flatness across a single 75.6 x 25 mm slide is ≤ 5 µm

Surface MicroRoughness of Glass B Slides

Measured using Digital instrument nanoScope Atomic Force Microscope (AFM)

Surface MicroRoughness of Glass B Slides

Typical MicroRoughness Ra < 3 nm

This data represents typical average values and is for reference only.

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