GB/T 42800-2023High purity opaque quartz glass (English PDF)

Foreword

This document was issued on 23 May 2023 by the State Administration for Market Regulation; Standardization Administration of the PRC and takes effect on 1 December 2023.

It is a GB/T standard: recommended rather than compulsory, but it is the text a Chinese reviewer applies when assessing a submission.

1 Scope

GB/T 42800-2023 specifies high purity opaque quartz glass. Opaque quartz is deliberately filled with fine bubbles so that it scatters infrared instead of transmitting it, which makes it a thermal insulator that keeps the chemical purity and thermal shock resistance of fused silica - the reason it lines the hot zones of semiconductor diffusion furnaces and photovoltaic crystal pullers, where any metallic contamination would reach the wafer. Purity is therefore specified more tightly than for any other glass. The standard sets the grades, the requirements, the test methods, the inspection rules and the marking, packaging, transport and storage provisions. It took effect on 1 December 2023.

This document specifies the classification, requirements, test methods, inspection rules,

marking, packaging, transportation, and storage of high-purity opaque quartz glass.

This document is applicable to high-purity opaque quartz glass materials with thermal

insulation in semiconductor, photovoltaic, and other fields.

2 Normative references

The following documents contain the provisions which, through normative reference in

this document, constitute the essential provisions of this document. For the dated

referenced documents, only the versions with the indicated dates are applicable to this

document; for the undated referenced documents, only the latest version (including all

the amendments) is applicable to this document.

GB/T 191 Packaging - Pictorial marking for handling of goods

GB/T 3284 Analytical method of the chemical composition in the quartz glass

GB/T 5432 Test method for density of glass by buoyancy

GB/T 10701-2008 Test methods for thermal stability of silica glass

GB/T 22588 Determination of thermal diffusivity or thermal conductivity by the

flash method

JC/T 2205 Terminology of quartz glass

3 Terms and definitions

The terms and definitions defined in JC/T 2205 apply to this document.

4 Grades

According to product appearance quality and impurity element content, it is divided

into semiconductor grade and photovoltaic grade.

5 Requirements

5.1 Specifications, dimensions, and dimensional deviations

They are negotiated by the supply and demand sides.

5.2 Appearance quality

5.2.1 The surface shall be smooth, uniform in color, and free from cracks, regular

microcracks, and scratches with a length greater than 10 mm or a width greater than 0.5

mm.

5.2.2 Visually it is milky white, and there shall be no transparent areas.

5.2.3 Semiconductor-grade high-purity opaque quartz glass shall not have speck spots,

coloured spots, and raw material particles; photovoltaic-grade high-purity opaque

quartz glass shall not have speck spots, coloured spots, and raw material particles with

a diameter greater than 1 mm, and the total number of speck spots, coloured spots, and

raw meal particles, whose diameters are not greater than 1 mm, in any area of 100 cm2

shall not exceed 4.

5.3 Density

The density shall not be greater than 2.15 g/cm3 and not less than 1.90 g/cm3.

5.4 Spectra transmittance

The spectra transmittance in the wavelength range of 380 nm~3000 nm shall be less

than 1.0%.

5.5 Thermal stability

After the test, there shall be no cracks, breaches, or skin flake-off.

5.6 Heat resistance

The deformation rate after the test shall not exceed 2.0%.

5.7 Thermal conductivity

At 20 degrees C, the thermal conductivity shall not be greater than 1.25 W/(m - K) and not less

than 1.00 W/(m - K).

5.8 Content of impurity elements

The impurity elements include aluminum (Al), iron (Fe), calcium (Ca), magnesium

(Mg), titanium (Ti), copper (Cu), cobalt (Co), nickel (Ni), manganese (Mn), lithium

Clean the sample in an ultrasonic bath, then wipe it clean with alcohol, rinse it with

deionized water, and dry it naturally; then, carry out the test according to the method

specified in GB/T 5432, and round the results to two decimal places.

6.5 Spectra transmittance

6.5.1 Sample

Take one piece of sample; the length and width are about 50 mm, the thickness after

grinding is 5 mm+/-0.5 mm, and there are no obvious speck spots, coloured spots, raw

material particles, or other defects that affect the test.

6.5.2 Test equipment

The requirements for the spectrophotometer:

a) It is able to measure the spectra transmittance of regular light;

b) The wavelength includes the range of 380 nm~3000 nm;

c) The transmittance measurement accuracy is not less than +/-1%.

6.5.3 Test procedure

The test is carried out as follows:

a) Wipe the surface of the sample with alcohol until it is clean, rinse it with

deionized water, and dry it at 110 °C+/-5 °C;

b) Use a spectrophotometer to measure the spectra transmittance of the sample

in the range of 380 nm~3000 nm for regular light.

6.5.4 Data processing

Read the maximum transmittance value and round the result to one decimal place.

6.6 Thermal stability

Carry out the test according to the air cooling method specified in GB/T 10701-2008.

Take three samples with a length of 50 mm+/-1 mm, a width of 50 mm+/-1 mm, and a

thickness of 5 mm+/-1 mm, keep them at the temperature of 1200 degrees C+/-10 degrees C for 30 min,

take them out and cool them in the air to room temperature.

6.7 Heat resistance

6.7.1 Samples

Take 3 samples; the length is 180 mm+/-2 mm, the width is 20 mm+/-1 mm, and the

H1 -- the arch height of the sample before the test, in millimeters (mm);

H2 -- the arch height of the sample after the test, in millimeters (mm).

The result is rounded to one decimal place, and the maximum deformation rate among

the three samples is taken as the measurement result.

6.8 Thermal conductivity

Clean the sample in an ultrasonic bath, then wipe it with alcohol, rinse it with deionized

water, and dry it at 110 degrees C+/-5 degrees C or dry it naturally; carry out the test according to the

method specified in GB/T 22588, and round the result to 2 decimal places.

6.9 Content of impurity elements

Carry out the test according to the method specified in GB/T 3284.

6.10 Maximum pore size, pore size standard deviation, porosity, and porosity

standard deviation

6.10.1 Samples

Take 3 samples; the length and width are about 50 mm, and the thickness after grinding

is 5 mm+/-0.5 mm. The test surface shall be free from concaves, scratches, cracks, and

other defects that affect the test.

6.10.2 Equipment

The requirements for pore analysis equipment:

a) It can measure the smallest pore diameter that is not greater than 0.1 um;

b) The moving range of the sample platform is not less than +/-60 mm, and the

smallest moving unit is not greater than 0.002 mm.

6.10.3 Test methods and procedures

The area method is used for measurement, and the test is carried out as follows:

a) Wipe the surface of the sample with alcohol until it is clean, use black ink or

a black oil-based pen to blacken the test surface of the sample, and fill the

pores of the test surface with white powder (such as limestone, talcum powder)

with a particle size of less than 10 um after the surface dries completely;

b) The equipment needs to be turned on and warmed up for 0.5 h; then, adjust the

focal length of the lens to make the phase clear, use the standard ruler to set

the conversion ratio between the actual size and the pixel, and set the

appropriate binarization threshold to clearly identify the pores; set the

measuring range to be 20 mmx20 mm, the minimum analysis pixel to be 2,

the circularity to be 0.3, and each frame of the image to be 5 mmx5 mm, a

total of (4x4) frames;

c) Measure the pore diameter and porosity of the three samples, respectively.

6.10.4 Data processing

The data is processed as follows:

a) Take the maximum value of the measured pore diameters of each sample as

the maximum pore diameter of the sample;

b) Calculate the standard deviation of the pore diameter of each sample;

c) Calculate the porosity standard deviation of the three samples;

d) The above results are all rounded to one decimal place.