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Borosilicate Glass
Special Properties
  • Our borosilicate glass comes with high temperature load capacity. (- up to 450°C permanent load; - up to 500°C temporary load (< 10h))
  • It gives low coefficient of thermal expansion and CTE (Coefficient of thermal expansion) value is matched to silicon. (anodic bonding)
  • High thermal shock resistance
  • Clear, colorless appearance
  • Low fluorescence
  • High UV transmission
  • High chemical resistance against acids, alkalies, and organic substances
  • Low alkali content in the glass composition
  • Low specific weight
Typical Applications

The borosilicate glass is commonly ideal for substrates for dielectric coatings, wafer substatrates, optical filter coating substrates, photovoltaics, neutron absorbers, as well as lighting applications. In the meanwhile, it find find its wide applications in the biotechnology, environmental technology, and measurement and sensor-technology.

Optical Properties

Optical transmission spectrum
Substrate thickness: 0.7mm / 3.3mm
Abbe constant ve: 65,41
Dispersion nF - nC: 71,4 x 10-4
Stress optical coefficient K: 4,0 x 10-6 mm2 N-1

Index of Refraction
Title Wavelength (nm) Refractive Index
ng 435,8 1,48015
nF' 479,9 1,47676
ne 546,1 1,47311
nd 587,6 1,47140
nD 589,3 1,47133
nC' 643,8 1,46953
nC 656,3 1,46916
Mechanical Properties

Density: 2,2 g/cm3 (25°C)
Young's modulus E: 64 kN/mm2(acc. to DIN 13 316)
Poisson's ratio μ: 0,2 (acc. to. DIN 13 316)
Shear modulus σ: 25 Mpa (acc. to. DIN 52 292 T 1)
Knoop hardness HK0,1/20: 480 (acc. to. ISO 9385)

Thermal Properties

Coefficient of thermal expansion: 3,25 x 10-6/K (20-300°C) (acc. to. ISO 7991)
Specific heat capacity cP: 0,83 kJ (kg x K)-1
Specific heat conductivity: 1,2 W (m x K)-1(90°C)
Transformation temperature Tg: 525°C

Viscosities of borosilicate glass

Working point (104 dPa): 1270°C
Softening point (107,6 dPa): 820°C
Annealing point (1013 dPa): 560°C
Strain point (1014,5 dPa): 518°C

Maximum operating temperatures σmax:
for short term load 500°C (< 10 h)
for long term load 450°C (≥ 10 h)
(only valid if the following RTG and RTS values are considered)

Resistance to thermal gradients (RTG):
110K (< 1h)
90K (1-100h)
80K (> 100h)

Resistance to thermal shock (RTS):
175K (thickness ≤ 3,8mm)
160K (thickness = 5,0-5,5mm)
150K (thickness = 6,5-15,0mm)
125K (thickness > 15,0mm)
(Details of test method are available on request.)

Chemical Properties

Hydrolytic Resistance: Class HGB 1 (acc. to. ISO 719 / DIN 12 111) Class HGA 1 (acc. to. ISO 720) Acid resistance: Class 1 (acc. to. ISO 1776 / DIN 12 116) Alkali resistance: Class A2 (acc. to. ISO 695 / DIN 52 322)

Electrical Properties

Dielectric constant εr: 4,6 (1 Mhz ; 25°C) Loss tangent (tan δ):37 x 10-4 (1 Mhz ; 25°C) Logarithm of electrical volume resistivity lgρ: 8,0 Ω x cm (250°C) 6,5 Ω x cm (350°C)