TW202038402A - Composite structure with insulating and heat dissipating coating, and manufacturing method and application thereof wherein the composite structure is advantageous in having a higher thermal conductivity and a higher breakdown voltage - Google Patents

Abstract

The invention provides a method for manufacturing a composite structure with an insulating and heat dissipating coating. The method includes following steps: (a) providing a metal substrate, wherein the metal substrate has a surface; and (b) using a thermal spraying to spray a coating composition on the surface to form an insulating and heat dissipating coating so as to obtain the composite structure with the insulating and heat dissipating coating. Based on a total weight of the coating composition, the coating composition includes 60 to 80 weight percent of silicon carbide and 20 to 40 weight percent of yttrium aluminum garnet. In comparison with the prior art, the manufacturing method simplifies the steps, and saves process time and cost. In addition, the composite structure with insulating and heat dissipation coating made by the manufacturing method is advantageous in having a higher thermal conductivity, a higher breakdown voltage and so on, which is more suitable to be used in manufacturing a heat dissipation circuit board of a semiconductor component.

Description

Composite structure with insulating and heat-dissipating coating, its preparation method and use

The present invention relates to a composite structure with an insulating and heat-dissipating coating, its preparation method and application, in particular to a composite structure mainly containing a silicon carbide coating, its preparation method and its application to a semiconductor element heat-dissipating circuit board.

When semiconductor components are in motion, because they cannot achieve 100% efficiency, their power consumption will be dissipated and transferred in the form of heat energy. If there is no good heat dissipation, the temperature will rise, which will easily affect the performance of the semiconductor components and even cause damage to the semiconductor components. This phenomenon is particularly obvious in high-power semiconductor components, such as insulated gate bipolar transistors (IGBT) and high-power light-emitting diodes (High Power LED). Therefore, the circuit board carrying these components must have good heat dissipation characteristics to maintain the performance and service life of the semiconductor components.

Generally speaking, the current circuit boards carrying high-power semiconductor components are mainly made of alumina ceramic insulating boards. Because ceramic insulating boards have the characteristics of thermal expansion coefficient close to semiconductors, high heat resistance and good electrical insulation, they are suitable for high Power semiconductor components. However, since the heat dissipation capacity of the ceramic insulation board is not sufficient to meet the requirements of high-power semiconductor components, it needs to be welded with a metal heat sink to improve the overall heat dissipation capacity. As a result, the production process includes the production of ceramic insulation The hot-pressing sintering step of the plate and the subsequent welding step of joining it with the metal result in a complicated, time-consuming and high-cost overall manufacturing process. Among them, the hot-pressing sintering of the ceramic insulating plate includes the following two steps:(1 ) Pre-pressing the ceramic powder using a mold; and (2) Performing hot-press sintering of the pre-pressed ceramic powder together with the mold under appropriate temperature, pressure and gas protection conditions to complete the ceramic insulating board, and so on , Which increases the time, cost and complexity of the process.

Not only that, with the rapid advancement of science and technology, the development of high-power semiconductor components has made alumina-based ceramic insulation boards unable to meet the demand for heat dissipation. Therefore, there is an increasing demand for the development of other high thermal conductivity ceramic insulation materials.

Therefore, in addition to the development of a more simplified, time-saving and cost-saving manufacturing process for heat dissipation circuit boards, the industry must also focus on the development of other high thermal conductivity ceramic insulating materials to enhance the application range and value of heat dissipation circuit boards for high-power semiconductor components. .

In view of the technical shortcomings faced by the above-mentioned prior art, the purpose of the present invention is to provide a method for preparing a composite structure with an insulating and heat-dissipating coating, which simplifies the overall manufacturing complexity because it does not require hot press sintering and welding processes And reduce the cost and time required.

Another object of the present invention is to provide a method for preparing a composite structure with an insulating and heat-dissipating coating, so that the composite structure with an insulating and heat-dissipating coating has excellent heat dissipation capability, electrical insulation and other characteristics.

To achieve the foregoing objective, the present invention provides a method for manufacturing a composite structure with an insulating and heat-dissipating coating, which includes the following steps: step (a): providing a metal substrate, wherein the metal substrate has a surface; and step (b) : Using a thermal spraying step to spray a coating composition on the surface to form an insulating and heat-dissipating coating to obtain the composite structure with the insulating and heat-dissipating coating; wherein, the total weight of the coating composition is As a benchmark, the coating composition contains 60 to 80 weight percent of silicon carbide (SiC) and 20 to 40 weight percent of yttrium aluminum garnet (YAG).

The present invention combines the selection of silicon carbide and yttrium aluminum garnet as the coating composition and the thermal spray method to form an insulating heat dissipation coating, which can use yttrium aluminum garnet to coat the surface of the silicon carbide to form protection, so that the coating composition can be used The thermal spray method forms an insulating and heat-dissipating coating on the metal substrate, thereby solving the cumbersome steps of forming a ceramic insulating plate through hot pressing and sintering and then welding with the metal; in addition, the silicon carbide in the coating composition Its thermal conductivity (126 W/mK) is about 4.5 times that of alumina (28 W/mK), which can improve the overall heat dissipation effect of the composite structure with insulating and heat dissipation coating.

Preferably, the coating composition can optionally be obtained by a step including agglomerated and sintered; for example, in order to further make the coating composition more suitable for the hot melt spraying process, the coating composition It can be obtained by granulation sintering and grinding and sieving steps. Accordingly, through the granulation step, the yttrium aluminum garnet can be coated on the surface of the silicon carbide to form protection, avoiding the problem that the silicon carbide is volatilized before it transforms into the molten state during the thermal spraying process, so that the coating composition The object is more suitable for the thermal spray process to form an insulating and heat-dissipating coating on the metal substrate.

Preferably, the particle size of the coating composition is between 10 micrometers (mm) and 90 mm, so as to be suitable for the hot melt injection process.

Preferably, the metal surface may be roughened through a sand blowing step to form a surface with a roughness (Ra) of 5 mm to 10 mm, which further improves the adhesion between the coating and the metal.

Preferably, the step of thermal spraying uses high velocity oxygen fuel spraying (HVOF). Generally speaking, when performing high-speed flame spraying, a fluid containing mixed gas or fuel is first provided to form a high-temperature flame, so that the temperature reaches 3200°C or higher, and then through the high-temperature flame, an expanding airflow with a speed of sound is generated. At the same time, the coating composition is fed into the high-temperature flame at an appropriate rate, and after a molten state is formed instantaneously, the high-speed airflow (flight time is about 10 ^-3 to 10 ^-4 seconds) hits at an appropriate distance On the metal surface, due to the relatively low temperature of the metal surface, the molten droplets are rapidly cooled, and a coating can be formed on the surface of the metal substrate. The thermal fusion injection step mentioned in the present invention does not specifically limit the various parameters during operation.

The present invention also provides a composite structure with an insulating and heat-dissipating coating prepared by the aforementioned method for preparing a composite structure with an insulating and heat-dissipating coating. The composite structure with an insulating and heat-dissipating coating includes a metal substrate and an insulating and heat-dissipating coating. Coating; wherein, the insulating and heat-dissipating coating contains 60 to 80 weight percent of silicon carbide and 20 to 40 weight percent of yttrium aluminum garnet.

Preferably, the thickness of the insulating and heat dissipation coating is between 100 mm and 800 mm. According to the present invention, since the insulating and heat-dissipating coating mainly contains silicon carbide and yttrium aluminum garnet, and its thickness is controlled within a specific range, it has both good heat dissipation capacity and electrical insulation characteristics, and it will not be too thick. The heat dissipation capacity is reduced, and the breakdown voltage (breakdown voltage) is not reduced because it is too thin and cannot withstand the applied voltage.

Preferably, the thermal conductivity of the composite structure with insulation and heat dissipation coating is between 50 W/mK and 400 W/mK.

Preferably, the direct current (DC) breakdown voltage of the composite structure with insulating and heat dissipation coating is between 3.6 kV and 4.5 kV.

Preferably, the bonding strength of the composite structure with an insulating and heat dissipation coating is between 5.0 kgf/mm ² and 7.5 kgf/mm ² .

The present invention also provides the use of the composite structure with an insulating and heat dissipation coating applied to a semiconductor element heat dissipation circuit board. Because the composite structure with an insulating and heat dissipation coating of the present invention has an insulating and heat dissipation coating containing silicon carbide and yttrium aluminum garnet, Its thermal conductivity is higher than the current heat dissipation circuit board using alumina as a ceramic insulation board, so it is more in line with the heat dissipation requirements of semiconductor components. More preferably, the semiconductor element is a high-power semiconductor element.

In the description, the range represented by "decimal value to large value", if not specified, means that the range is greater than or equal to the small value to less than or equal to the large value. For example: 60 weight percent to 80 weight percent, which means that the range is "greater than or equal to 60 weight percent to less than or equal to 80 weight percent".

To sum up, the present invention sprays the coating composition containing silicon carbide and yttrium aluminum garnet on the surface of a metal substrate through the thermal spraying step to form an insulating and heat-dissipating coating. The composite structure with insulating and heat-dissipating coating does not require the steps of hot-pressing sintering and welding, which is simpler, more time-saving and lower in cost; in addition, the silicon carbide in the insulating and heat-dissipating coating has better properties than alumina The higher thermal conductivity, therefore, has a better heat dissipation effect, and can better meet the heat dissipation requirements of high-power semiconductor components in the future, thereby enhancing the value of the present invention in the industry.

Specific examples are listed below to illustrate the implementation of the present invention. Those skilled in the art can easily understand the advantages and effects of the present invention through the content of this specification, and make various modifications and changes without departing from the spirit of the present invention. , To implement or apply the content of the present invention.

Example 1

Provide a stainless steel plate with a length and width of 6 cm (cm) and a thickness of 2 millimeters (mm) as the metal substrate. The surface will be sandblasted to provide a surface with a roughness of 5.6 mm, which will then contain 70 The coating composition of silicon carbide and 30% by weight of yttrium aluminum garnet is introduced into the high-speed flame spray gun at a powder feeding rate of 15 rpm, and the high-speed flame spray gun is operated to After the coating composition is in a molten state or a semi-molten state above 3200°C, it is sprayed on the surface of the stainless steel plate 152 mm apart from the muzzle at a surface rate of 600 mm/s to form a consistent and dense insulation and heat dissipation coating. The thickness is about 300 mm, the porosity is less than 1%, the hardness is 780 (Hv 0.3), and the roughness is less than 2 mm.

Example 2

Provide a stainless steel round rod with a diameter of 1 inch and a length of 8 cm, and sandblasting on the transverse surface to provide a surface with a roughness of 5.6 mm. The remaining steps are the same as in Example 1. An insulating and heat-dissipating coating with a thickness of approximately 300 mm is formed on the transverse surface of the stainless steel rod.

Comparative example 1

The manufacturing steps of Comparative Example 1 are the same as those of Example 1, except that Comparative Example 1 uses alumina powder for high-speed flame spraying, and finally forms an alumina coating with a thickness of about 300 mm.

Comparative example 2

The manufacturing steps of Comparative Example 2 are the same as those of Example 2, except that Comparative Example 2 uses alumina powder for high-speed flame spraying, and finally forms an alumina coating with a thickness of about 300 mm.

Test example 1 : DC Measurement of breakdown voltage

The DC breakdown voltage is the minimum voltage that converts a part of the insulator into an electrical conductor; if you want to meet the requirements of high-power semiconductor heat-dissipating circuit boards, the DC breakdown voltage must reach 3.5 kV or more to maintain good electrical insulation characteristics. Hereinafter, Example 1 and Comparative Example 1 are selected to measure the DC breakdown voltage, using a voltage and current (IV) measuring machine, whose model is HP 4156 or Keithley 4220. When the measurement is performed, a DC power supply with a gradually increasing voltage is applied to the coating, and the current passing through the metal substrate is measured at the same time. When the measured current passing through the metal substrate increases instantly, the voltage applied to the coating is now It is called DC breakdown voltage, and its measurement results are listed in Table 1 below. Table 1: The measurement results of the DC breakdown voltage of Example 1 and Comparative Example 1 Maximum (kV) Minimum (kV) Average (kV) Example 1 3.909 3.86 3.885 Comparative example 1 2.362 2.336 2.349

From the results in Table 1 above, it can be seen that Example 1 has a higher DC breakdown voltage than Comparative Example 1. It can be seen that the present invention uses an insulating and heat-dissipating coating containing silicon carbide and yttrium aluminum garnet, compared to the existing Alumina, which is commonly used in technology, is used as a ceramic insulating material, which has more excellent electrical insulation properties, and can withstand higher voltages while still maintaining insulation properties.

Test example 2 ：Measurement of thermal conductivity

In order to prevent the heat energy released by the high-power semiconductor components from accumulating and generating high temperatures during operation, which may affect or damage these components, the heat dissipation requirements of the high-power semiconductor components are very important. Hereinafter, Example 1 and Comparative Example 1 are selected for the measurement of thermal conductivity. The measurement is performed according to the ISO22007-2 test standard, using the Thin Film Method (Transient Plane Source Method, TPS). Method) for measurement, and the measurement results are listed in Table 2 below. Table 2: Measurement results of the thermal conductivity of Example 1 and Comparative Example 1 Thermal conductivity (W/mK) Example 1 20.74 Comparative example 1 10.05

From the results of Table 2 above, it can be seen that the thermal conductivity of Example 1 is about twice that of Comparative Example 1, which shows that when the insulating and heat-dissipating coating of the present invention is used to replace alumina, the overall heat dissipation capacity can indeed be improved, which is more consistent with high The need for heat dissipation of power semiconductor components.

Test example 3 ：Measurement of bond strength between coating and metal substrate

According to the ASTM C633-79 standard, Example 2 and Comparative Example 2 were selected to measure the bonding strength, and the measurement results are listed in Table 3 below. Table 3: Measurement results of bond strength of Example 2 and Comparative Example 2 Coating bond strength (kgf/mm ² ) Example 2 6.03 Comparative example 2 4.13

From the results in Table 3 above, it can be seen that the bonding strength between the insulating and heat-dissipating coating and the stainless steel substrate in Example 2 is significantly higher than the bonding strength between the alumina coating and the stainless steel substrate in Comparative Example 2. Therefore, the insulation of the present invention Compared with the prior art alumina coating and the metal substrate, the heat dissipation coating and the metal substrate have a better bonding force, thereby reducing the high temperature generated when the high-power semiconductor device is activated, causing the coating to be removed from the metal substrate. In addition, the high bonding strength also ensures that the coating and the metal substrate are closely combined. Therefore, the insulating and heat dissipation coating of the present invention can be applied to various metal substrates (especially copper, aluminum alloy and other high thermal conductivity metals). , Even stainless steel substrate), and improve the heat transfer efficiency between the insulating heat dissipation coating and the metal substrate.

In summary, the present invention can complete the preparation of a composite structure with an insulating and heat-dissipating coating by using only the steps of thermal spraying, eliminating the previous complicated steps that require hot pressing and sintering and then welding, and simplifying the overall manufacturing process At the same time, it also saves time and cost; in addition, the present invention specially selects a coating composition containing silicon carbide and yttrium aluminum garnet for thermal spraying to form an insulating and heat-dissipating coating on the metal substrate, which is compared with the previous The commonly used aluminum oxide coating has higher thermal conductivity, DC breakdown voltage, and bonding strength with the metal substrate, thereby improving the applicable range and value of the composite structure with the insulating and heat-dissipating coating of the present invention.

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Claims (11)

A method for manufacturing a composite structure with an insulating and heat-dissipating coating includes the following steps: Step (a): providing a metal substrate, wherein the metal substrate has a surface; and Step (b): Use a thermal spraying step to spray a coating composition on the surface to form an insulating and heat-dissipating coating to obtain the composite structural material with an insulating and heat-dissipating coating; wherein the coating is composed of Based on the total weight of the material, the coating composition includes 60 to 80 weight percent of silicon carbide and 20 to 40 weight percent of yttrium aluminum garnet. The manufacturing method according to claim 1, wherein, in the step (b), the thermal spraying step uses a high-speed flame spraying method. The manufacturing method according to claim 1, wherein, in the step (b), the thermal injection temperature is 3200°C or higher. The manufacturing method according to any one of claims 1 to 3, wherein the particle size of the coating composition is between 10 mm and 90 mm. The manufacturing method according to claim 4, wherein the coating composition is obtained by a step including granulation and sintering. A composite structure with an insulating and heat-dissipating coating made by the manufacturing method according to any one of claims 1 to 5, comprising a metal substrate and an insulating and heat-dissipating coating; wherein the insulating and heat-dissipating coating contains 60 weight Percent to 80% by weight of silicon carbide and 20% to 40% by weight of yttrium aluminum garnet. The composite structure with an insulating and heat-dissipating coating according to claim 6, wherein the thickness of the insulating and heat-dissipating coating is between 100 mm and 800 mm. The composite structure with insulation and heat dissipation coating as described in claim 6 or 7, its thermal conductivity is between 50 W/mK and 400 W/mK. The composite structure with insulation and heat dissipation coating as described in claim 6 or 7, its DC breakdown voltage is between 3.6 kV and 4.5 kV. The composite structure with an insulating and heat-dissipating coating according to claim 6 or 7, wherein the bonding strength of the insulating and heat-dissipating coating and the metal substrate is between 5.0 kgf/mm ² and 7.5 kgf/mm ² . A composite structure with an insulating and heat-dissipating coating as described in any one of claims 6 to 10 is applied to a semiconductor element heat-dissipating circuit board.