GB/T 5593-2015Structure ceramic materials used in electronic component and device (English PDF)

3.4 Forsterite ceramics

Ceramics, with magnesium silicate (Mg2SiO4) as the main crystal phase, containing a certain amount of barium glass phase. It is characterized by high mechanical strength, excellent dielectric properties, and a coefficient of linear expansion similar to that of metal titanium, which therefore allows a good sealing-in with metal titanium. Its disadvantage is poor thermal stability.

Note: Forsterite ceramics is used to manufacture insulating parts of electron tubes and semiconductor devices, and is widely used in small cermet tubes. In addition, it is also used in the manufacture of resistor substrates and ceramic capacitors.

3.5 Alumina ceramics

Ceramics, with alumina as the main component and alpha-Al2O3 as the main crystal phase, such as A-75 ceramics, A-95 ceramics, A-97 ceramics, A-99.9 ceramics, etc. It is characterized by high mechanical strength, excellent dielectric properties at high temperatures, good vacuum air tightness, low dielectric loss, high hardness, good thermal conductivity, high temperature resistance, wear resistance, corrosion resistance, oxidation resistance and the like.

Note: It is mainly used in the manufacture of insulating structural parts of ultra-high frequency and high-power electric vacuum devices, thick film, thin film and microwave integrated circuit substrates, shells and brackets of silicon rectifiers, and radome etc.

3.6 Porous alumina ceramics

Ceramics - containing a large number of closed pores and through open pores - whose main component is alpha-Al2O3. The pores are required to be evenly distributed, and have a certain mechanical strength, which can withstand thermal shocks.

Note: It can be used as a support in the tube, a catalyst carrier, etc.

3.7 Beryllia ceramics

Ceramics, of which the main crystal phase is beryllium oxide with wurtzite structure, and the secondary crystal phase is magnesium-aluminum-beryllium compound.

According to the content of beryllium oxide, it can be divided into B-95 ceramics and B-99 ceramics. It is characterized by high thermal conductivity; its thermal conductivity is almost equal to that of pure aluminum. It has superior thermal shock resistance, and its electrical properties are similar to alumina ceramics.

Note: It is used to make transistor shells, tube sockets, heat sinks, high-power integrated circuits and microwave integrated circuit substrates, microwave windows, and reducers for space technology and atomic energy neutron, etc.

3.8 Aluminium nitride ceramics

Ceramics whose main crystal phase is mainly aluminum nitride (AlN). White color; hexagonal crystal; good thermal conductivity, second only to beryllia ceramics; a high thermal conductivity material; good thermal shock resistance; stable chemical properties.

Note: It is used for the manufacture of ceramic substrates for high-power thick-film integrated circuits, substrates for high-power semiconductor devices and ultra-large-scale integrated circuits; it can also be used as high-temperature corrosion-resistant materials, etc.

3.9 Boron nitride ceramics

Ceramics, with boron nitride as the main component, whose crystal structure is hexagonal or cubic. Boron nitride ceramics with a hexagonal structure is similar to graphite - with good lubricity and low hardness, easy to machine - which is a good machinable material. Cubic boron nitride ceramics has high hardness, similar to diamond. Boron nitride ceramics, of low density, good thermal and chemical stability, has outstanding features such as high thermal conductivity and low electrical conductivity, easy processing, as well as excellent lubricating properties; it also has good high temperature resistance; its high temperature performance is better than alumina porcelain; it has penetrating ability to microwave radiation.

Note: It can be used for radar windows, as well as for high-power transistor sockets, tube shells, heat sinks and microwave output windows.

3.10 For A-90, A-95, A-99, A-99.5, B-97, B-99 ceramic materials, the specified temperature

is 800 °C ± 10 °C, repeated 10 times is qualified.

For M2S ceramic materials, the test temperature is 400 °C ± 10 °C, repeated five times is qualified.

5.9 Coefficient of linear expansion

When measuring the coefficient of linear expansion of ceramic materials, it shall be carried out according to the method specified in GB/T 5594.3.

5.10 Thermal conductivity

When measuring the thermal conductivity of ceramic materials, it shall be carried out according to the method specified in GB/T 5598.

5.11 Dielectric constant and dielectric loss tangent

5.11.1 Dielectric constant and dielectric loss tangent (1 MHz)

When measuring the dielectric constant and dielectric loss tangent of ceramic materials at 1 MHz or under high temperature conditions, it shall be carried out according to the method specified in GB/T 5594.4.

5.11.2 Dielectric constant and dielectric loss tangent (10 GHz)

When measuring the dielectric constant and dielectric loss tangent of ceramic materials at 10 GHz, it shall be carried out according to the method specified in GB/T 5597.

5.12 Volume resistivity

When measuring the volume resistivity of ceramic materials, it shall be carried out according to the method specified in GB/T 5594.5.

5.13 Breakdown strength

When measuring the breakdown strength of ceramic materials, it shall be carried out on DC high-voltage equipment. The equipment shall ensure that the voltage can rise evenly, the boosting rate is not greater than 1 000 V/s, and the voltage measurement error shall not be greater than ±5%. See Table 2 for sample and electrode requirements. The test shall be carried out in insulating oil or transformer oil with sufficient insulating properties. When measuring the thickness, the error shall not be greater than ±0.002 mm. The test result is calculated according to Formula (3):

Where:

E - electric strength of the sample, in kilovolts per millimeter (kV/mm);

U - breakdown voltage of the sample, in kilovolts (kV); h - thickness of the sample, in millimeters (mm).

5.14 Chemical stability

When measuring the chemical stability of ceramic materials, it shall be carried out according to the method specified in GB/T 5594.6.

5.15 Porosity

When measuring the porosity of ceramic materials, it shall be carried out according to the method specified in GB/T 1966.

5.16 Grain size

When measuring the grain size of ceramic materials, it shall be carried out according to the method specified in GB/T 5594.8.

5.17 Hardness

When measuring the hardness of ceramic materials, it shall be carried out according to the method specified in Appendix A.

6.1 Inspection classification

6.1.1 General

The inspection of ceramic materials is divided into ex-factory inspection (delivery inspection) and type inspection (routine inspection).

6.1.2 Ex-factory inspection

Each batch of ceramic materials shall undergo ex-factory inspection according to the test items specified in Table 3.

A.5 Samples

Test samples shall meet the following requirements:

a) Sample requirements: 1 cm × 1 cm square, thickness not less than 4 mm;

b) The parallelism between the test surface and the opposite machine surface is not greater than 0.3 mm/cm;

c) The test surface shall be a smooth plane, and the roughness shall be no more than 0.8 µm according to the test value Ra specified in GB/T 1031-1995.

A.6 Test procedures

The test procedures are as follows:

a) Place the hardness testing machine on a solid foundation and adjust it to a level with a levelness of 0.2/1 000;

b) Make the test surface of the sample perpendicular to the axis of the indenter;

c) Adjust the focal distance of the microscope;

d) Select the test force to be 49 N (5 kg). For special cases, the test force can be selected separately, which shall be indicated in the test report;

e) Before the test or after replacing the indenter, use the corresponding standard Vickers hardness block to verify whether the shape of the indentation and the measured value of the hardness are correct;

f) Apply a load at a loading speed of 0.3 mm/s. There shall be no shock or vibration during the test; keep the test force for 10 s ~ 15 s, and accurately measure the diagonal length of the indentation;

g) The number of indentations on the same test surface shall not be less than 5;

h) The distance between the centers of two adjacent indentations is 10 ~ 15 times the length of the diagonal of the indentation, and the distance from the center of the indentation to the edge of the sample is at least 10 ~ 15 times the average length of the diagonal of the indentation;

i) After the test, when the shape of the indentation on the test surface is incomplete or deformed, the result is invalid.

A.7 Calculation of hardness value

The calculation formula of Vickers hardness is shown in Formula (A.1): […]