A composite powder potting material of lead-free multi-component bismuth-based low-melting glass and ceramic powder, and its preparation method and application

Abstract

The present invention relates to a composite powder potting material of a lead-free multi-component bismuth-based low-melting glass and ceramic powder, and a preparation method and application thereof. By weight percentage, it includes the following components: 60-100% of glass powder, 0-40% of ceramic powder, and the sum of the mass percentages of the glass powder and the ceramic powder is 100%; the glass powder is a lead-free multi-component bismuth-based low-melting glass powder, and the composition of the lead-free multi-component bismuth-based low-melting glass powder is made up of the following components by mass percentage: 70-85% of Bi2O3, 5-15% of B2O3, 5-15% of ZnO, 0-10% of BaO, and a combination of one or two of CuO or Fe2O3 in total of 0-5%, and the sum of the mass percentages of the above components is 100%. The high-temperature potting solution of the composite powder potting material of the lead-free multi-component bismuth-based low-melting glass and ceramic powder provided by the present invention can achieve the reliability target requirements for the normal operation of the potted device at a high temperature of 300 °C or even 350 °C, and is applicable to the packaging of wide-bandgap power semiconductor devices such as silicon carbide and gallium nitride.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic packaging materials, and in particular to a composite powder potting material of lead-free multi-component bismuth-based low-melting glass and ceramic powder, a preparation method thereof, and an application thereof. Background Art

[0002] Power semiconductor devices are crucial for efficient energy conversion in power electronics applications such as electric vehicles, data centers, power grids, renewable energy processing, and consumer electronics, and have promoted the development of wide-bandgap semiconductors (WBG) such as silicon carbide (SiC) and gallium nitride. Ultra-wide-bandgap (UWBG) semiconductor materials represented by Ga 2 O 3 also achieve key progress in power applications. To meet the requirements for the stable operation of power semiconductor devices in environments such as high temperature and high pressure, the packaging materials used are required to simultaneously have characteristics such as a high glass transition temperature (tg), high metal adhesion, low hygroscopicity, and low ion concentration. Traditional potting materials are mainly polymers, such as epoxy resins, silicone resins, and polyimides, which will undergo thermal degradation (decomposition) under the influence of temperature rise (around 175 - 200 °C), changing their properties and being unable to meet the requirements of the new generation of semiconductor packaging.

[0003] The Chinese invention patent with the patent application number 202211428348.1 provides a high-temperature potting solution with an organic-inorganic thin film stack, which can achieve the reliability target requirements for the normal operation of the potted device at 200 °C and 250 °C. The Chinese invention patent with the patent application number 202210618233.2 provides a maleimide resin-based composition for the packaging of third-generation semiconductor devices, and its cured product has a high glass transition temperature and high flexural strength at both room temperature and 250 °C. SiC and GaN devices theoretically have the ability to operate at temperatures up to 600 °C, and the poor high-temperature stability of the potting material is an important reason restricting the device's ability. Therefore, for the new generation of wide-bandgap power semiconductor devices, developing new potting materials with high heat resistance and high breakdown voltage has important research significance and application value.

[0004] Glass has good electrical insulation, durability, high-temperature stability and other characteristics, and is an ideal candidate for the potting material of wide-bandgap power devices. Through the retrieval of existing scientific and technological literature, it is found that the method of pouring molten lead-based glass liquid at 500 °C successfully potted SiC MOSFET. After the glass packaging module was soaked at 250 °C for 1000 hours, the appearance and partial discharge inception voltage (PDIV) of the module did not change. The results show that the high-temperature stability of glass packaging is far better than that of high-temperature polymers and does not affect the static and dynamic characteristics of the chip.

[0005] Lead-based low-melting glass, as a traditional semiconductor packaging material, has been widely used in the production practice of semiconductor devices. However, due to the large stress generated by the mismatched expansion coefficients between the glass and the substrate, cracking occurs. To reduce the stress, a polymer buffer layer is added between the glass and the DBC substrate, but this simultaneously reduces the withstand voltage performance of the module. In addition, the relatively high potting temperature may cause device damage. Meanwhile, lead is severely harmful to both humans and the environment. Green, environmentally friendly, and lead-free have become the development direction of low-temperature packaging glass. Summary of the Invention

[0006] In view of the above defects or improvement requirements of the prior art, the present invention provides a lead-free multi-component bismuth-based low-melting glass and ceramic powder composite powder potting material, its preparation method and application. The purpose is to complete the potting of wide-bandgap semiconductor power devices by compounding low-melting bismuth-based glass powder and inorganic ceramic powder. The composite powder is heated together with the device, and the glass powder softens and sinters, enabling the power device to withstand high temperatures of 300 °C or even 350 °C and being able to match the faster switching speed and higher breakdown voltage of wide-bandgap power devices.

[0007] The object of the present invention can be achieved by the following technical solutions:

[0008] The present invention provides a lead-free multi-component bismuth-based low-melting glass and ceramic powder composite powder potting material, which includes the following components by weight percentage: 60-100% of glass powder, 0-40% of ceramic powder, and the ceramic powder is not 0, and the sum of the mass percentages of the glass powder and the ceramic powder is 100%;

[0009] The glass powder is a lead-free multi-component bismuth-based low-melting glass powder.

[0010] The lead-free multi-component bismuth-based low-melting glass powder is composed of the following components by mass percentage:

[0011] Bi 2 O 3 70-85%,

[0012] B 2 O 3 5-15%,

[0013] ZnO 5-15%,

[0014] BaO 0-10%, and not 0

[0015] CuO or Fe 2 O 3 One or a combination of two of them in total 0-5%, and not 0,

[0016] The sum of the mass percentages of the above components is 100%.

[0017] In one embodiment of the present invention, the mass ratio of the lead-free multi-component bismuth-based low-melting-point glass powder to the ceramic powder is 1:(0 - 0.667), and the ceramic powder is not 0.

[0018] In one embodiment of the present invention, the ceramic powder is an inorganic oxide or nitride.

[0019] In one embodiment of the present invention, the ceramic powder is selected from one or more of fused silica, crystalline silica, fumed silica, alumina, aluminum hydroxide, calcium carbonate, magnesium oxide, magnesium hydroxide, boron nitride, aluminum nitride, silicon nitride, magnesium carbonate, calcium hydroxide, clay, barium titanate, lead titanate, wollastonite or talc powder.

[0020] In one embodiment of the present invention, the ceramic powder contains fused silica, and the content of fused silica is 50 - 100 wt% of the total amount of the ceramic powder, preferably 90 - 100 wt%.

[0021] In one embodiment of the present invention, the average particle size of the ceramic powder is 0.01 - 30 μm.

[0022] In one embodiment of the present invention, the particle size of the lead-free multi-component bismuth-based low-melting-point glass powder is 5 - 20 μm.

[0023] In one embodiment of the present invention, the particle size of the composite powder encapsulation material of the lead-free multi-component bismuth-based low-melting-point glass and the ceramic powder is 5 - 20 μm.

[0024] The composite powder encapsulation material of the lead-free multi-component bismuth-based low-melting-point glass and the ceramic powder provided by the present invention is a composite powder material. The composite powder can be softened and sintered between 400 - 450 °C and can remain stable at a temperature of 350 °C after sintering.

[0025] In the present invention, through the combination of the low-melting-point bismuth-based glass powder and the inorganic ceramic powder, the composite powder is heated together with the device, the glass powder is softened and sintered, and the encapsulation of the wide-bandgap semiconductor power device is completed, so that the power device can withstand a high temperature of 300 °C or even 350 °C, and can match the faster switching speed and higher breakdown voltage of the wide-bandgap power device.

[0026] The present invention further provides a preparation method of the composite powder encapsulation material of the lead-free multi-component bismuth-based low-melting-point glass and the ceramic powder, comprising the following steps:

[0027] (1) Mix the raw materials of the lead-free multi-component bismuth-based low-melting-point glass powder in the formula amount evenly, and then through melting, water quenching and ball milling, obtain the lead-free multi-component bismuth-based low-melting-point glass powder;

[0028] (2) Mix the lead-free multi-component bismuth-based low-melting-point glass powder obtained in step (1) with ceramic powder according to the ratio to obtain a composite powder encapsulation material of lead-free multi-component bismuth-based low-melting-point glass and ceramic powder for encapsulating wide-bandgap power devices.

[0029] In one embodiment of the present invention, the preparation of the lead-free multi-component bismuth-based low-melting-point glass powder in step (1) includes the following steps:

[0030] (1.1) Accurately weigh the composition ratio of the lead-free multi-component bismuth-based low-melting-point glass powder, mix it evenly and put it into a high-temperature furnace, melt it at 1000 - 1300 °C for 2 h to obtain a high-temperature glass melt;

[0031] (1.2) Pour the high-temperature glass melt in step (1.1) into deionized water for rapid quenching to form crushed glass;

[0032] (1.3) Grind the crushed glass in step (1.2) in a ball mill with a material-to-ball ratio of 1:(3 - 5), and pass through an 800-mesh sieve to obtain the lead-free multi-component bismuth-based low-melting-point glass powder with a particle size of 5 - 20 μm.

[0033] The present invention further provides the application of the composite powder encapsulation material of lead-free multi-component bismuth-based low-melting-point glass and ceramic powder, which is used for encapsulating wide-bandgap power devices. The specific method is as follows:

[0034] Heat the composite powder encapsulation material of lead-free multi-component bismuth-based low-melting-point glass and ceramic powder together with the unencapsulated wide-bandgap power device. The glass powder softens and sinters to complete the encapsulation of the wide-bandgap semiconductor power device, enabling the power device to withstand high temperatures of 300 °C or even 350 °C, and being able to match the faster switching speed and higher breakdown voltage of the wide-bandgap power device.

[0035] At the same time, co-firing is achieved at a lower temperature, reducing damage to the device and improving the encapsulation success rate.

[0036] In one embodiment of the present invention, the application of the composite powder encapsulation material of lead-free multi-component bismuth-based low-melting-point glass and ceramic powder for encapsulating wide-bandgap power devices specifically includes the following steps:

[0037] (1) Place an appropriate amount of the composite powder encapsulation material of lead-free multi-component bismuth-based low-melting-point glass and ceramic powder and the unencapsulated wide-bandgap power device in a packaging mold;

[0038] (2) Place the above mold in a nitrogen atmosphere furnace or a vacuum furnace, heat it to 400 - 450 °C at a heating rate of 5 °C / min, hold for 10 - 30 minutes, and cool it to room temperature at a rate of 2 °C / min.

[0039] In one embodiment of the present invention, the wide bandgap power device includes a silicon carbide (SiC)-based power device, a gallium nitride (GaN)-based power device, a zinc oxide (ZnO)-based power device, a gallium oxide (Ga 2 O 3 )-based power devices, diamond-based power devices, etc. are wide bandgap power semiconductor devices.

[0040] The high-temperature potting scheme of the composite powder potting material of lead-free multi-component bismuth-based low-melting-point glass and ceramic powder provided by the present invention can achieve the reliability target requirements for the normal operation of the filled device at high temperatures of 300°C and 350°C. The glass powder can soften and sinter between 400 and 450°C, and can remain stable at a temperature of 350°C after sintering. However, the thermal expansion coefficient (CTE) of the glass itself does not match the components of the power device (chips, bonding wires, etc.), resulting in large stress, easy cracks, and affecting the potting performance; while the inorganic ceramic powder has a low expansion coefficient and excellent electrical properties. After adding ceramic powder, it can effectively reduce the expansion coefficient of the composite powder, reduce stress, and improve the breakdown strength. Therefore, this potting material composite of glass and ceramic powder can enable the encapsulated semiconductor power device to operate normally at high temperatures. At the same time, this potting scheme will provide a more feasible reference for the exploration of potting materials for wide bandgap semiconductor power devices in the future.

[0041] In general, the above technical solutions conceived by the present invention can achieve at least the following beneficial effects compared with the prior art:

[0042] (1) The lead-free multi-component bismuth-based low-melting-point glass and ceramic powder composite powder potting material provided by the present invention can achieve the reliability target requirement for the normal operation of the filled device at high temperatures of 300°C and 350°C. Compared with the commonly used polymer potting materials, this potting material has good high temperature resistance, which overcomes the failure of the device module caused by wide bandgap power devices in a higher temperature working environment. More importantly, for wide bandgap semiconductor power devices with higher temperature resistance and faster switching speed (such as SiC power devices), the currently commonly used potting materials can only support SiC power modules to operate at a maximum of 175°C, while the lead-free multi-component bismuth-based low-melting-point glass and ceramic powder composite powder potting material provided by the present application can enable the power device to continue to work at high temperatures above 300°C or even 350°C without failure.

[0043] (2) In the present invention, inorganic ceramic powder is added to reduce the expansion coefficient of the composite powder, reduce the stress inside the device, remove the polymer buffer layer required for the glass potting material, improve the overall breakdown strength of the device, and improve the durability of the device.

[0044] (3) The potting material of the composite powder of multi-component bismuth-based low-melting glass and ceramic powder provided by the present invention is used as a lead-free material, and meeting the requirements of being green, environmentally friendly and lead-free has become the development direction of low-temperature encapsulation glass. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 . Schematic diagram of potting a power device with the potting material.

[0046] As indicated by the reference numerals in the figure: 1, bonding layer material; 2, power semiconductor chip; 3, potting material; 4, bonding wire; 5, copper-clad ceramic substrate (DBC); 6, bottom plate. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0047] The present invention will be described in detail below with reference to specific embodiments. Obviously, the described embodiments are only partial embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0048] Unless otherwise specified, the experimental methods in the following embodiments are all conventional methods, and the experimental reagents and materials involved are all conventional chemical reagents and materials unless otherwise specified.

[0049] Embodiment 1

[0050] This embodiment provides a lead-free potting material of a composite powder of multi-component bismuth-based low-melting glass and ceramic powder, which includes the following components by weight percentage: 80% glass powder and 20% ceramic powder;

[0051] The glass powder is a lead-free multi-component bismuth-based low-melting glass powder, and the composition of the lead-free multi-component bismuth-based low-melting glass powder is made up of the following components by mass percentage: 83% Bi 2 O 3 , 5% B 2 O 3 , 6% ZnO, 3% BaO, 3% CuO.

[0052] In this embodiment, the ceramic powder is fused silica.

[0053] The preparation method of the lead-free potting material of the composite powder of multi-component bismuth-based low-melting glass and ceramic powder provided by this embodiment includes the following steps:

[0054] (1) Preparation of lead-free multi-component bismuth-based low-melting glass powder:

[0055] (1.1) Accurately weigh the composition ratio of the lead-free multi-component bismuth-based low-melting glass powder formula, that is, by mass percentage: 83% Bi 2 O 3, 5% of B 2 O 3 , 6% of ZnO, 3% of BaO, 3% of CuO. After mixing them evenly, put them into a high-temperature furnace and melt them at 1000 - 1300 °C for 2 h to obtain a high-temperature glass melt;

[0056] (1.2) Pour the high-temperature glass melt in step (1.1) into deionized water for rapid quenching to form crushed glass;

[0057] (1.3) Grind the crushed glass in step (1.2) in a ball mill with a material-to-ball ratio of 1:3, and pass through an 800-mesh sieve to obtain the lead-free multi-component bismuth-based low-melting-point glass powder with a particle size of 5 - 20 μm.

[0058] (2) Mix the lead-free multi-component bismuth-based low-melting-point glass powder obtained in step (1) with ceramic powder according to the ratio, and mix them evenly according to the ratio of 80 wt% of the low-melting-point lead-free glass powder to 20 wt% of spherical fused silica, then the composite powder potting material of the lead-free multi-component bismuth-based low-melting-point glass and ceramic powder for potting wide-bandgap power devices can be obtained.

[0059] This embodiment also provides the application of the composite powder potting material of the lead-free multi-component bismuth-based low-melting-point glass and ceramic powder in potting wide-bandgap power devices, which specifically includes the following steps:

[0060] (1) Place 50 g of the composite powder potting material of the lead-free multi-component bismuth-based low-melting-point glass and ceramic powder in this embodiment and the un-potted wide-bandgap power device in a packaging mold;

[0061] (2) Place the above mold in a nitrogen atmosphere furnace or a vacuum furnace, heat it up to 450 °C at a heating rate of 5 °C / min, keep it warm for 30 minutes, and then cool it down to room temperature at a rate of 2 °C / min.

[0062] In this embodiment, the wide-bandgap power device includes a silicon carbide (SiC)-based power device.

[0063] The structural schematic diagram of the potting material potting the power device is as Figure 1 shown. On the bottom plate 6, the copper-clad ceramic substrate 5 is connected through the bonding layer material 1. On the copper-clad ceramic substrate 5, the power semiconductor chip 2 is connected through the bonding layer material 1. The power semiconductor chips 2 are connected through bonding wires 4. The potting material 3 pottingly connects the power semiconductor chip 2, the bonding wire 4, the copper-clad ceramic substrate 5, and the bottom plate 6 together.

[0064] Example 2

[0065] This embodiment provides a composite powder potting material of a lead-free multi-component bismuth-based low-melting-point glass and ceramic powder, which includes the following components by weight percentage: 74% of glass powder and 26% of ceramic powder;

[0066] The glass powder is a lead-free multi-component bismuth-based low-melting-point glass powder. The lead-free multi-component bismuth-based low-melting-point glass powder is composed of the following components by mass percentage: 70% Bi 2 O 3 , 15% B 2 O 3 , 6% ZnO, 7% BaO, 2% Fe 2 O 3 .

[0067] In this embodiment, the ceramic powder is crystalline silica.

[0068] The preparation method of the composite powder encapsulation material of the lead-free multi-component bismuth-based low-melting-point glass and the ceramic powder provided in this embodiment includes the following steps:

[0069] (1) Preparation of lead-free multi-component bismuth-based low-melting-point glass powder:

[0070] (1.1) Accurately weigh the composition ratio of the lead-free multi-component bismuth-based low-melting-point glass powder formula, that is, by mass percentage: 70% Bi 2 O 3 , 15% B 2 O 3 , 6% ZnO, 7% BaO, 2% Fe 2 O 3 . Mix them evenly and put them into a high-temperature furnace, melt at 1000 - 1300 °C for 2 h to obtain a high-temperature glass melt;

[0071] (1.2) Pour the high-temperature glass melt in step (1.1) into deionized water for rapid quenching to form crushed glass;

[0072] (1.3) Fine-grind the crushed glass in step (1.2) in a ball mill, with a material-to-ball ratio of 1:5, and pass through an 800-mesh sieve to obtain the lead-free multi-component bismuth-based low-melting-point glass powder with a particle size of 5 - 20 μm.

[0073] (2) Mix the lead-free multi-component bismuth-based low-melting-point glass powder obtained in step (1) and the ceramic powder evenly according to the ratio of 74 wt% of the low-melting-point lead-free glass powder and 26 wt% of the crystalline silica, and the composite powder encapsulation material of the lead-free multi-component bismuth-based low-melting-point glass and the ceramic powder for encapsulating wide-bandgap power devices can be obtained.

[0074] This embodiment also provides the application of the composite powder encapsulation material of the lead-free multi-component bismuth-based low-melting-point glass and the ceramic powder in the encapsulation of wide-bandgap power devices, which specifically includes the following steps:

[0075] (1) Put 50 g of the composite powder encapsulation material of lead-free multi-component bismuth-based low-melting-point glass and ceramic powder and the unencapsulated wide-bandgap power device into an encapsulation mold;

[0076] (2) Place the above mold in a nitrogen atmosphere furnace or a vacuum furnace, heat it to 500 °C at a heating rate of 5 °C / min, keep it warm for 20 minutes, and cool it to room temperature at a rate of 2 °C / min.

[0077] In this embodiment, the wide-bandgap power device includes a silicon carbide (SiC)-based power device.

[0078] Example 3

[0079] This embodiment provides a composite powder encapsulation material of lead-free multi-component bismuth-based low-melting-point glass and ceramic powder, which includes the following components by weight percentage: 75% glass powder and 25% ceramic powder;

[0080] The glass powder is a lead-free multi-component bismuth-based low-melting-point glass powder. The composition of the lead-free multi-component bismuth-based low-melting-point glass powder is made up of the following components by mass percentage: 85% Bi 2 O 3 , 5% B 2 O 3 , 5% ZnO, 2% BaO, 3% Fe 2 O 3 .

[0081] In this embodiment, the ceramic powder is alumina.

[0082] The preparation method of the composite powder encapsulation material of lead-free multi-component bismuth-based low-melting-point glass and ceramic powder provided in this embodiment includes the following steps:

[0083] (1) Preparation of lead-free multi-component bismuth-based low-melting-point glass powder:

[0084] (1.1) Accurately weigh the composition ratio of the lead-free multi-component bismuth-based low-melting-point glass powder formula, that is, by mass percentage: 85% Bi 2 O 3 , 5% B 2 O 3 , 5% ZnO, 2% BaO, 3% Fe 2 O 3 . Mix them evenly and put them into a high-temperature melting furnace, melt them at 1000-1300 °C for 2 h to obtain a high-temperature glass melt;

[0085] (1.2) Pour the high-temperature glass melt in step (1.1) into deionized water for rapid quenching to form crushed glass;

[0086] (1.3) Grind the crushed glass in step (1.2) in a ball mill with a material-to-ball ratio of 1:3, and pass through an 800-mesh sieve to obtain the lead-free multi-component bismuth-based low-melting-point glass powder with a particle size of 5-20 μm.

[0087] (2) Mix the lead-free multi-component bismuth-based low-melting-point glass powder obtained in step (1) with ceramic powder according to the ratio, and mix evenly according to the ratio of 75 wt% of the low-melting-point lead-free glass powder and 25 wt% of alumina, then the composite powder encapsulation material of the lead-free multi-component bismuth-based low-melting-point glass and ceramic powder for encapsulating wide-bandgap power devices can be obtained.

[0088] This embodiment also provides the application of the composite powder encapsulation material of the lead-free multi-component bismuth-based low-melting-point glass and ceramic powder in encapsulating wide-bandgap power devices, which specifically includes the following steps:

[0089] (1) Place 50 g of the composite powder encapsulation material of the lead-free multi-component bismuth-based low-melting-point glass and ceramic powder in this embodiment and the unencapsulated wide-bandgap power device in a packaging mold;

[0090] (2) Place the above mold in a nitrogen atmosphere furnace or a vacuum furnace, heat it to 450 °C at a heating rate of 5 °C / min, hold for 10 minutes, and cool it to room temperature at a rate of 2 °C / min.

[0091] In this embodiment, the wide-bandgap power device includes a silicon carbide (SiC)-based power device.

[0092] Example 4

[0093] This embodiment provides a composite powder encapsulation material of a lead-free multi-component bismuth-based low-melting-point glass and ceramic powder, which includes the following components by weight percentage: 60% glass powder and 40% ceramic powder;

[0094] The glass powder is a lead-free multi-component bismuth-based low-melting-point glass powder, and the composition of the lead-free multi-component bismuth-based low-melting-point glass powder is made of the following components by mass percentage: 72% Bi 2 O 3 , 8% B 2 O 3 , 15% ZnO, 5% CuO.

[0095] In this embodiment, the ceramic powder is magnesium oxide.

[0096] The preparation method of the composite powder encapsulation material of the lead-free multi-component bismuth-based low-melting-point glass and ceramic powder provided in this embodiment includes the following steps:

[0097] (1) Preparation of lead-free multi-component bismuth-based low-melting-point glass powder:

[0098] (1.1) Weigh accurately the composition ratio of the lead-free multi-component bismuth-based low-melting-point glass powder according to the formula amount, that is, by mass percentage: 72% of Bi 2 O 3 , 8% of B 2 O 3 , 15% of ZnO, 5% of CuO. After mixing them evenly, put them into a high-temperature furnace and melt them at 1000 - 1300 °C for 2 h to obtain a high-temperature glass melt;

[0099] (1.2) Pour the high-temperature glass melt in step (1.1) into deionized water for rapid quenching to form crushed glass;

[0100] (1.3) Grind the crushed glass in step (1.2) in a ball mill with a material-to-ball ratio of 1:5, and pass through an 800-mesh sieve to obtain the lead-free multi-component bismuth-based low-melting-point glass powder with a particle size of 5 - 20 μm.

[0101] (2) Mix evenly the lead-free multi-component bismuth-based low-melting-point glass powder obtained in step (1) with ceramic powder according to the ratio, that is, mix them evenly according to the ratio of 60 wt% of the low-melting-point lead-free glass powder and 40 wt% of magnesium oxide, and then the composite powder encapsulation material of the lead-free multi-component bismuth-based low-melting-point glass and ceramic powder for encapsulating wide-bandgap power devices can be obtained.

[0102] This embodiment also provides the application of the composite powder encapsulation material of the lead-free multi-component bismuth-based low-melting-point glass and ceramic powder in encapsulating wide-bandgap power devices, which specifically includes the following steps:

[0103] (1) Place 50 g of the composite powder encapsulation material of the lead-free multi-component bismuth-based low-melting-point glass and ceramic powder in this embodiment and the unencapsulated wide-bandgap power device in a packaging mold;

[0104] (2) Place the above mold in a nitrogen atmosphere furnace or a vacuum furnace, heat it to 480 °C at a heating rate of 5 °C / min, keep it warm for 30 minutes, and then cool it to room temperature at a rate of 2 °C / min.

[0105] In this embodiment, the wide-bandgap power device includes a silicon carbide (SiC)-based power device.

[0106] Example 5

[0107] This embodiment provides a composite powder encapsulation material of a lead-free multi-component bismuth-based low-melting-point glass and ceramic powder, which includes the following components by weight percentage: 69% of glass powder and 31% of ceramic powder;

[0108] The glass powder is a lead-free multi-component bismuth-based low-melting-point glass powder, and the composition of the lead-free multi-component bismuth-based low-melting-point glass powder is made of the following components by mass percentage: 75% of Bi 2 O3 , 10% of B 2 O 3 , 5% of ZnO, 5% of BaO, 5% of Fe 2 O 3 .

[0109] In this embodiment, the ceramic powder is boron nitride.

[0110] The preparation method of the lead-free multi-component bismuth-based low-melting-point glass and ceramic powder composite powder encapsulation material provided in this embodiment includes the following steps:

[0111] (1) Preparation of lead-free multi-component bismuth-based low-melting-point glass powder:

[0112] (1.1) Accurately weigh the composition ratio of the lead-free multi-component bismuth-based low-melting-point glass powder formula, that is, by mass percentage: 75% of Bi 2 O 3 , 10% of B 2 O 3 , 5% of ZnO, 5% of BaO, 5% of Fe 2 O 3 , mix them evenly and put them into a high-temperature furnace, melt at 1000 - 1300 °C for 2 h to obtain a high-temperature glass melt;

[0113] (1.2) Pour the high-temperature glass melt in step (1.1) into deionized water for rapid quenching to form crushed glass;

[0114] (1.3) Fine-grind the crushed glass in step (1.2) in a ball mill, with a material-to-ball ratio of 1:4, and pass through an 800-mesh sieve to obtain the lead-free multi-component bismuth-based low-melting-point glass powder with a particle size of 5 - 20 μm.

[0115] (2) Mix the lead-free multi-component bismuth-based low-melting-point glass powder obtained in step (1) with the ceramic powder according to the ratio, and mix them evenly according to the ratio of 69 wt% of the low-melting-point lead-free glass powder and 31 wt% of boron nitride, then the lead-free multi-component bismuth-based low-melting-point glass and ceramic powder composite powder encapsulation material for encapsulating wide-bandgap power devices can be obtained.

[0116] This embodiment also provides the application of the lead-free multi-component bismuth-based low-melting-point glass and ceramic powder composite powder encapsulation material in the encapsulation of wide-bandgap power devices, which specifically includes the following steps:

[0117] (1) Place 50 g of the lead-free multi-component bismuth-based low-melting-point glass and ceramic powder composite powder encapsulation material of this embodiment and the unencapsulated wide-bandgap power device in a packaging mold;

[0118] (2) Place the above-mentioned mold in a nitrogen atmosphere furnace or a vacuum furnace, heat it up to 490 °C at a heating rate of 5 °C / min, hold for 30 minutes, and then cool it down to room temperature at a rate of 2 °C / min.

[0119] In this embodiment, the wide bandgap power device includes a silicon carbide (SiC)-based power device.

[0120] Example 6

[0121] This embodiment provides a composite powder encapsulation material of lead-free multi-component bismuth-based low-melting-point glass and ceramic powder, which includes the following components by weight percentage: 70% glass powder and 30% ceramic powder;

[0122] The glass powder is a lead-free multi-component bismuth-based low-melting-point glass powder, and the composition of the lead-free multi-component bismuth-based low-melting-point glass powder is made up of the following components by mass percentage: 74% Bi 2 O 3 , 6% B 2 O 3 , 7% ZnO, 10% BaO, 3% Fe 2 O 3 .

[0123] In this embodiment, the ceramic powder is aluminum nitride.

[0124] The preparation method of the composite powder encapsulation material of lead-free multi-component bismuth-based low-melting-point glass and ceramic powder provided in this embodiment includes the following steps:

[0125] (1) Preparation of lead-free multi-component bismuth-based low-melting-point glass powder:

[0126] (1.1) Accurately weigh the composition ratio of the lead-free multi-component bismuth-based low-melting-point glass powder formula, that is, by mass percentage: 74% Bi 2 O 3 , 6% B 2 O 3 , 7% ZnO, 10% BaO, 3% Fe 2 O 3 . Mix them evenly and put them into a high-temperature melting furnace, melt at 1000 - 1300 °C for 2 h to obtain a high-temperature glass melt;

[0127] (1.2) Pour the high-temperature glass melt in step (1.1) into deionized water for rapid quenching to form crushed glass;

[0128] (1.3) Grind the crushed glass in step (1.2) in a ball mill with a material-to-ball ratio of 1:5, and pass through an 800-mesh sieve to obtain the lead-free multi-component bismuth-based low-melting-point glass powder with a particle size of 5 - 20 μm.

[0129] (2) Mix the lead-free multi-component bismuth-based low-melting glass powder obtained in step (1) with ceramic powder according to the ratio, and mix them evenly according to the ratio of 70 wt% of the low-melting lead-free glass powder to 30 wt% of aluminum nitride, then the composite powder encapsulation material of the lead-free multi-component bismuth-based low-melting glass and ceramic powder for encapsulating wide-bandgap power devices can be obtained.

[0130] This embodiment also provides the application of the composite powder encapsulation material of the lead-free multi-component bismuth-based low-melting glass and ceramic powder in the encapsulation of wide-bandgap power devices, which specifically includes the following steps:

[0131] (1) Place 50 g of the composite powder encapsulation material of the lead-free multi-component bismuth-based low-melting glass and ceramic powder in this embodiment and the unencapsulated wide-bandgap power device in a packaging mold;

[0132] (2) Place the above mold in a nitrogen atmosphere furnace or a vacuum furnace, heat it to 500 °C at a heating rate of 5 °C / min, hold for 25 minutes, and cool it to room temperature at a rate of 2 °C / min.

[0133] In this embodiment, the wide-bandgap power device includes a silicon carbide (SiC)-based power device.

[0134] The composition, glass transition temperature, softening temperature, sintering temperature, crystallization temperature, thermal expansion coefficient (30 - 200 °C), breakdown strength of the wide-bandgap power device encapsulated, etc. of the composite powder encapsulation materials of the lead-free multi-component bismuth-based low-melting glass and ceramic powder obtained in Examples 1 - 6 are shown in Table 1.

[0135] Table 1

[0136]

[0137]

[0138] It can be seen from Table 1 that for the encapsulation materials of the composite powders of the lead-free multi-component bismuth-based low-melting glass and ceramic powder prepared by the present invention, by adjusting the formulation composition and controlling the heat treatment process, each example sample has a suitable expansion coefficient and has good compatibility with other materials in the device. The encapsulated wide-bandgap power devices of the present invention have good high-temperature stability, excellent breakdown resistance, and high reliability.

[0139] In the above-mentioned Embodiments 1 to 6, the descriptions of each embodiment have their own focuses. For the parts not detailed in a certain embodiment, reference may be made to the relevant descriptions of other embodiments. As described above, these are only preferred embodiments of the present invention and do not impose any formal restrictions on the present invention. Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications by using the disclosed technical content without departing from the technical solution of the present invention.

[0140] The above description of the embodiments is for the convenience of those of ordinary skill in the art to understand and use the invention. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative labor. Therefore, the present invention is not limited to the above embodiments, and the improvements and modifications made by those skilled in the art without departing from the scope of the present invention according to the disclosure of the present invention should be within the protection scope of the present invention.

Claims

1. A composite powder potting material of lead-free multi-component bismuth-based low-melting glass and ceramic powder, characterized in that, by weight percentage, it comprises the following components: 80% of glass powder and 20% of ceramic powder; The glass powder is a lead-free multi-component bismuth-based low-melting-point glass powder. The lead-free multi-component bismuth-based low-melting-point glass powder is composed of the following components by mass percentage: 83% of Bi 2 O 3 , 5% of B 2 O 3 , 6% of ZnO, 3% of BaO, 3% of CuO; the ceramic powder is fused silica, and the average particle size of the ceramic powder is 0.01 - 30 μm; the particle size of the lead-free multi-component bismuth-based low-melting glass powder is 5 - 20 μm.

2. A preparation method of the composite powder potting material of lead-free multi-component bismuth-based low-melting glass and ceramic powder according to claim 1, characterized in that, it comprises the following steps: (1) Preparation of lead-free multi-component bismuth-based low-melting glass powder: (1.1)Accurately weigh the composition ratio of the formula amount of lead-free multi-component bismuth-based low-melting glass powder, that is, by mass percentage: 83% Bi 2 O 3 , 5% B 2 O 3 , 6% ZnO, 3% BaO, 3% CuO. After mixing them evenly, put them into a high-temperature furnace and melt them at 1000 - 1300 °C for 2 h to obtain a high-temperature glass melt; (1.2) Pour the high-temperature glass melt in step (1.1) into deionized water for rapid quenching to form crushed glass; (1.3) Grind the crushed glass in step (1.2) in a ball mill with a material-to-ball ratio of 1:3, and pass through an 800-mesh sieve to obtain the lead-free multi-component bismuth-based low-melting glass powder with a particle size of 5 - 20 μm; (2) Mix the lead-free multi-component bismuth-based low-melting glass powder obtained in step (1) with the ceramic powder according to the ratio, and mix them evenly according to the ratio of 80wt% of the low-melting lead-free glass powder and 20wt% of spherical fused silica, then the composite powder potting material of lead-free multi-component bismuth-based low-melting glass and ceramic powder for potting wide-bandgap power devices can be obtained.

3. An application of the composite powder potting material of lead-free multi-component bismuth-based low-melting glass and ceramic powder according to claim 1, characterized in that, it is used for potting wide-bandgap power devices, and the specific method is: (1) Place an appropriate amount of the composite powder potting material of lead-free multi-component bismuth-based low-melting glass and ceramic powder and the un-potted wide-bandgap power device in a packaging mold; (2) Place the above mold in a nitrogen atmosphere furnace or a vacuum furnace, heat it up to 400 - 450 °C at a heating rate of 5 °C / min, keep it warm for 10 - 30 minutes, and cool it down to room temperature at a rate of 2 °C / min; The potting of the wide-bandgap semiconductor power device is completed, so that the power device can withstand a high temperature of 300 °C or even 350 °C, and can match the switching speed and breakdown voltage of the wide-bandgap power device.

4. An application of a composite powder potting material of lead-free multi-component bismuth-based low-melting glass and ceramic powder according to claim 3, characterized in that, the wide-bandgap semiconductor power device includes one or more of a silicon carbide-based power device, a gallium nitride-based power device, a zinc oxide-based power device, a gallium oxide-based power device, and a diamond-based power device.

Images