Vehicle-mounted charging silicon nitride ceramic substrate

Abstract

This invention discloses a silicon nitride ceramic substrate for vehicle charging, belonging to the field of heat dissipation technology for power device packaging in new energy vehicles. It comprises a ceramic substrate consisting of a silicon nitride ceramic matrix, an upper copper layer, and a lower copper layer. The silicon nitride ceramic matrix is ​​the main crystalline phase, and 0.5–5 wt% seed crystals are doped within it. This invention, through the design of a high-heat-dissipation, high-reliability silicon nitride ceramic substrate adapted to the high-voltage fast charging conditions of vehicles, employs a dense ceramic matrix with a main phase, seed crystal doping modification, and a multi-component composite sintering aid system. Combined with an AMB double-sided oxygen-free copper-plated nickel structure, the ceramic substrate achieves a thermal conductivity of 90–120 W / (m·K), a stable thermal expansion coefficient of 3.2 ± 0.2 ppm / K, and is highly compatible with SiC / GaN power chips. It also exhibits a bending strength ≥850 MPa and a breakdown voltage ≥2.5 kV, solving the industry bottlenecks of insufficient heat dissipation, thermal mismatch failure, insufficient high-voltage insulation, and short lifespan in existing vehicle power substrates.

Description

Technical Field

[0001] This invention relates to the field of power device packaging and heat dissipation technology for new energy vehicles, and in particular to a silicon nitride ceramic substrate for vehicle charging. Background Technology

[0002] With the rapid upgrade of new energy vehicles towards high voltage and high-power fast charging, 800V high-voltage platforms have become the mainstream configuration in the industry. On-board chargers, voltage converters, and on-board fast charging power modules commonly use SiC and GaN wide-bandgap power chips. These chips have high power density and high heat flux density, and operate in a high-temperature range of 150–200℃ for extended periods. This places extremely stringent automotive-grade requirements on the thermal conductivity, thermal expansion matching, structural strength, high-voltage insulation performance, and environmental reliability of the packaging substrate.

[0003] Currently, the mainstream packaging substrates for automotive power modules in the industry have significant technical shortcomings and cannot adapt to high-voltage, high-power fast charging conditions: Alumina ceramic substrates have a thermal conductivity of only 20–30 W / (m·K), resulting in poor thermal conductivity. Under high-power operation, heat accumulation is severe, the chip junction temperature is too high, and power decay, thermal failure, and device damage are likely to occur, making them unsuitable for high-power fast charging above 30kW; Aluminum nitride ceramic substrates have excellent thermal conductivity, but their coefficient of thermal expansion is 4.5–5.5ppm / K, which deviates significantly from the 3.5–4.5ppm / K thermal expansion range of SiC chips. Under automotive conditions, frequent high and low temperature alternation and start-stop shocks can easily generate interfacial thermal stress, causing substrate cracking, copper layer peeling, and solder joint failure, resulting in poor automotive reliability; Ordinary commercial silicon nitride ceramic substrates have simple manufacturing processes and have not undergone automotive-specific modification and optimization. Their thermal conductivity is only 40–60 W / (m·K), resulting in insufficient heat dissipation margin. Their crystal phase structure is disordered and the density is uneven, and their strength and thermal shock resistance cannot meet the automotive-grade requirements for 10,000 cycles of life.

[0004] To address the technical shortcomings of existing vehicle power modules, such as poor thermal conductivity and severe high-temperature heat accumulation of alumina ceramic substrates, mismatch between the thermal expansion coefficient of aluminum nitride ceramic substrates and silicon carbide chips, easy cracking due to high and low temperature thermal shock, and low thermal conductivity and insufficient structural strength of ordinary silicon nitride substrates, which cannot meet the reliability requirements of 800V high-voltage high-power fast charging vehicles, a new vehicle charging silicon nitride ceramic substrate is proposed. Summary of the Invention

[0005] The purpose of this invention is to solve the problems existing in the prior art and to propose a silicon nitride ceramic substrate for vehicle charging.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A vehicle-mounted charging silicon nitride ceramic substrate includes a ceramic substrate composed of a silicon nitride ceramic substrate, an upper copper layer, and a lower copper layer, wherein the silicon nitride ceramic substrate is... The silicon nitride ceramic matrix is ​​dominated by 0.5–5 wt% of [a specific chemical component]. Seed crystals, and configuration Composite sintering aid; the silicon nitride ceramic matrix has the following performance parameters: thermal conductivity 90–120 W / (m・K), coefficient of thermal expansion 3.2±0.2 ppm / K, flexural strength ≥850 MPa, and a SiC power module is disposed on the copper overlay layer, and the SiC power module is connected to the solder layer through solder wiring pins.

[0007] Preferably, the thickness of the silicon nitride ceramic substrate is 0.3–0.8 mm, and the breakdown voltage of the silicon nitride ceramic substrate is ≥2.5 kV, which is suitable for the 800V high-voltage on-board charging insulation use conditions of new energy vehicles.

[0008] Preferably, both the upper and lower copper layers are made of oxygen-free copper and have a nickel-plated anti-oxidation layer on their surfaces. The thickness of the upper copper layer is 0.3–0.5 mm, and the thickness of the lower copper layer is 0.5–1.0 mm.

[0009] Preferably, the ceramic substrate is compatible with new energy vehicle OBC on-board chargers, DC / DC converters, and SiC / GaN high-voltage fast charging power modules, and can stably support continuous fast charging of 30–60kW high power, with a chip steady-state junction temperature ≤125℃.

[0010] Preferably, the ceramic substrate has undergone 10,000 high and low temperature alternating cycles from -40℃ to 200℃, with no substrate cracking, no copper layer peeling, and no solder joint detachment, meeting the requirements for vehicle-mounted vibration resistance, damp heat resistance, and long service life.

[0011] Preferably, the SiC power module includes a SiC power chip or a GaN power chip.

[0012] Preferably, the lower copper layer is located at the bottom and serves as a heat dissipation bonding and fixing layer, while the upper copper layer is located above the lower copper layer and serves as a chip soldering and circuit wiring layer.

[0013] Preferably, the silicon nitride ceramic substrate is located between the upper copper layer and the lower copper layer, and the silicon nitride ceramic substrate has dense columnar crystals, which facilitates a significant improvement in the density of the silicon nitride ceramic substrate and the integrity of the thermal conductivity pathway.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This solution, through the setting of silicon nitride ceramic substrate, enables the ceramic substrate to have ultra-high thermal conductivity and heat dissipation, solving the problem of heat accumulation in high power. The thermal conductivity of the substrate of this invention is stable at 90–120 W / (m・K), which is 3–4 times that of traditional alumina substrate, greatly improving the heat dissipation capability in both the lateral and longitudinal directions. It can reduce the junction temperature of SiC chip by 30–50℃ under high power fast charging conditions, and control the steady-state junction temperature within 125℃, thus preventing high-temperature thermal failure.

[0015] 2. This solution precisely matches the thermal expansion of the SiC chip, ensuring that the CTE of the substrate with extremely strong thermal shock resistance is stable at 3.2±0.2ppm / K. This perfectly matches the thermal expansion characteristics of the SiC chip, completely avoiding the thermal mismatch defects of the aluminum nitride substrate. Under tens of thousands of high and low temperature alternating cycles from -40℃ to 200℃, there is no cracking, delamination, or solder detachment, and the thermal stress stability reaches the highest level of automotive grade.

[0016] 3. This solution, through the design of ultra-high structural strength of ceramic substrate, can be adapted to vehicle vibration and impact conditions. The substrate has a bending strength of ≥850MPa, excellent fracture toughness, and outstanding impact resistance, bending resistance, and fatigue resistance. It is suitable for complex working conditions of vehicle driving with bumps, vibrations, and impacts, and will not deform or crack after long-term use.

[0017] 4. The ceramic substrate in this invention has high-voltage insulation safety performance, is compatible with 800V high-voltage platform substrate with a breakdown voltage ≥2.5kV, has stable insulation performance, and has no leakage or breakdown risk during high-voltage operation, fully meeting the high-voltage electrical safety specifications for new energy vehicles.

[0018] 5. The ceramic substrate in this invention has environmental aging resistance, achieving automotive-grade ultra-long life surface nickel plating protection combined with a dense ceramic matrix, and has excellent resistance to damp heat, salt spray and oxidation, which can meet the requirements of 15 years of long-term reliable use of the whole vehicle. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the location of the SiC power module in a silicon nitride ceramic substrate for vehicle charging, as proposed in this invention. Figure 2 This is a schematic diagram of the connection between the SiC power module and the ceramic substrate in a vehicle-mounted charging silicon nitride ceramic substrate proposed in this invention. Figure 3 This is a schematic diagram of the structure of the ceramic substrate in the silicon nitride ceramic substrate for vehicle charging proposed in this invention; Figure 4 This is a schematic diagram showing the location of the silicon nitride ceramic substrate in a vehicle-mounted charging silicon nitride ceramic substrate proposed in this invention.

[0020] In the diagram: 1. Lower copper layer; 2. Silicon nitride ceramic substrate; 3. Upper copper layer; 4. SiC power module; 5. Solder layer. Detailed Implementation

[0021] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0022] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," "top / bottom," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0023] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed," "equipped with," "sleeved / connected," "connected," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0024] Example, refer to Figures 1 to 4 A silicon nitride ceramic substrate for vehicle charging includes a ceramic substrate composed of a silicon nitride ceramic substrate 2, an upper copper layer 3, and a lower copper layer 1. The silicon nitride ceramic substrate 2 is... The main crystalline phase is silicon nitride ceramic matrix 2, internally doped with 0.5–5 wt% of [missing information]. Seed crystals, and configuration Composite sintering aid; the silicon nitride ceramic matrix 2 has the following performance parameters: thermal conductivity 90–120 W / (m・K), thermal expansion coefficient 3.2±0.2ppm / K, bending strength ≥850MPa, and a SiC power module 4 is provided on the copper overlay 3. The SiC power module 4 is connected to the solder layer 5 through solder wiring pins. Furthermore, the silicon nitride ceramic substrate 2 has a thickness of 0.3–0.8 mm and a breakdown voltage ≥2.5 kV, making it suitable for the insulation operation of 800V high-voltage on-board chargers in new energy vehicles. Both the upper copper layer 3 and the lower copper layer 1 are made of oxygen-free copper with a nickel-plated anti-oxidation layer on the surface. The upper copper layer 3 has a thickness of 0.3–0.5 mm and serves as the chip soldering and circuit wiring layer. The lower copper layer 1 has a thickness of 0.5–1.0 mm and serves as the heat dissipation bonding and fixing layer. This ceramic substrate is suitable for new energy vehicle OBC on-board chargers, DC / DC converters, and SiC / GaN high-voltage on-board chargers. The high-voltage fast charging power module can stably support continuous fast charging of 30–60kW high power. The steady-state junction temperature of the chip is ≤125℃. The ceramic substrate has undergone 10,000 high and low temperature alternating cycle tests from -40℃ to 200℃, with no substrate cracking, no copper layer peeling, and no solder joint detachment. It meets the requirements of vehicle vibration resistance, damp heat resistance, and long life. The SiC power module 4 includes a SiC power chip or a GaN power chip. The silicon nitride ceramic substrate 2 is located between the upper copper layer 3 and the lower copper layer 1. The silicon nitride ceramic substrate 2 has dense columnar crystals, which can significantly improve the density of the silicon nitride ceramic substrate 2 and the integrity of the heat conduction path. It should be noted that: for the 30kW automotive OBC dedicated silicon nitride ceramic substrate, this embodiment is adapted to the 30kW automotive charger power module of a conventional 800V platform for new energy vehicles: the silicon nitride ceramic substrate 2 has a thickness of 0.5mm. The seed crystal doping concentration is 2wt%, and the composite sintering aid ratio is reasonable. The measured thermal conductivity of the ceramic substrate is 95 W / (m・K), the coefficient of thermal expansion is 3.2ppm / K, the bending strength is 880MPa, and the breakdown voltage is 3kV. The upper copper layer 3 is 0.4mm thick, the lower copper layer 1 is 0.8mm thick, and the copper layer surfaces are plated with 5μm of nickel. Assembled for automotive OBC power modules, it operates continuously at full power of 30kW with a maximum chip junction temperature ≤123℃. After 10,000 cycles of high and low temperature cycling from -40℃ to 180℃, the substrate structure remains intact, the copper layer shows no peeling, and the electrical and heat dissipation performance remains unaffected, making it suitable for all operating conditions of conventional automotive fast charging.

[0025] This embodiment is designed for 60kW high-voltage fast charging high-power module substrates, and is adapted to 800V high-voltage platform high-power fast charging and automotive high-power DC / DC converter modules. It optimizes seed distribution and sintering density, increasing the thermal conductivity of the ceramic substrate to 110W / (m・K), maintaining a stable coefficient of thermal expansion of 3.1ppm / K, achieving an insulation withstand voltage ≥3kV, and a stable structural strength ≥900MPa. When applied to 60kW continuous high-power output conditions, the module's steady-state maximum junction temperature is ≤130℃, exhibiting high overall efficiency, good thermal uniformity, and no thermal failure or structural damage during long-term high-load operation, thus meeting the ultra-high-power fast charging requirements of high-end vehicle models. The purpose of this invention is to overcome the shortcomings of existing automotive power substrates, such as poor thermal conductivity, thermal expansion mismatch, weak thermal shock resistance, insufficient high-voltage insulation, and low reliability. This invention provides a silicon nitride ceramic substrate specifically for automotive charging, achieving high thermal conductivity and heat dissipation, high thermal expansion matching with SiC chips, high-voltage insulation safety, strong vibration and thermal shock resistance, and long-term stable operation for 800V high-voltage, 30–60kW high-power automotive fast charging. To achieve the above objectives, this invention adopts the following technical solution: The overall structure is a ceramic substrate with double-sided AMB copper-plated nickel integrated structure. The core utilizes β-phase seed-induced modification of the silicon nitride crystal phase structure, combined with multi-component composite sintering aids, to precisely control the thermal conductivity and thermal expansion coefficient of the ceramic substrate, achieving optimal synergy in thermal conductivity, strength, thermal matching, and insulation performance. The silicon nitride ceramic substrate 2 is made of high purity... As the base body, introduce trace amounts Seed-induced dense growth of columnar crystals significantly improves the density and thermal conductivity of the silicon nitride ceramic matrix; combined with... The composite additive system reduces sintering defects, refines grains, and stabilizes the coefficient of thermal expansion, making the overall mechanical, thermal, and insulation properties of the ceramic substrate fully adaptable to the harsh automotive operating conditions. The upper and lower surfaces of the ceramic substrate are composited with oxygen-free copper layers using AMB active metal brazing technology. The upper thin copper layer (copper layer 3) is adapted for precision wiring and chip soldering, while the lower thick copper layer (copper layer 1) enhances the stability of the thermal conductivity and heat dissipation interface. Nickel plating on the copper layer surface improves its resistance to oxidation, damp heat, and salt spray in automotive environments. The silicon nitride ceramic substrate of this invention has a controllable process, stable performance, and strong adaptability. It can be mass-produced industrially and can be widely used in core components such as 800V high-voltage platform on-board chargers, DC / DC voltage converters, and SiC / GaN high-voltage fast charging power modules for new energy vehicles. It significantly improves the heat dissipation capacity, working stability, and service life of high-power fast charging systems, and has extremely high industrialization value and market promotion prospects.

[0026] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A vehicle-mounted charging silicon nitride ceramic substrate, comprising a ceramic substrate composed of a silicon nitride ceramic substrate (2), an upper copper layer (3), and a lower copper layer (1), characterized in that, The silicon nitride ceramic matrix (2) is The silicon nitride ceramic matrix (2) is dominated by 0.5–5 wt% of [a specific chemical component]. Seed crystals, and configuration Composite sintering aid; the silicon nitride ceramic matrix (2) has the following performance parameters: thermal conductivity 90–120 W / (m・K), thermal expansion coefficient 3.2±0.2ppm / K, bending strength ≥850MPa, and a SiC power module (4) is provided on the copper overlay (3). The SiC power module (4) is connected to the solder layer (5) through solder wiring pins.

2. The on-board charging silicon nitride ceramic substrate according to claim 1, characterized in that, The thickness of the silicon nitride ceramic substrate (2) is 0.3–0.8 mm, and the breakdown voltage of the silicon nitride ceramic substrate (2) is ≥2.5 kV, which is suitable for the use of 800V high-voltage vehicle charging insulation in new energy vehicles.

3. The on-board charging silicon nitride ceramic substrate according to claim 1, characterized in that, Both the upper copper layer (3) and the lower copper layer (1) are made of oxygen-free copper and have a nickel-plated anti-oxidation layer on their surfaces. The thickness of the upper copper layer (3) is 0.3–0.5 mm and the thickness of the lower copper layer (1) is 0.5–1.0 mm.

4. The on-board charging silicon nitride ceramic substrate according to claim 1, characterized in that, The ceramic substrate is compatible with new energy vehicle OBC on-board chargers, DC / DC converters, and SiC / GaN high-voltage fast charging power modules, and can stably support continuous fast charging of 30–60kW high power with a chip steady-state junction temperature ≤125℃.

5. The on-board charging silicon nitride ceramic substrate according to claim 1, characterized in that, The ceramic substrate has undergone 10,000 high and low temperature alternating cycles from -40℃ to 200℃, with no substrate cracking, no copper layer peeling, and no solder joint detachment, meeting the requirements for vehicle-mounted vibration resistance, damp heat resistance, and long service life.

6. The on-board charging silicon nitride ceramic substrate according to claim 1, characterized in that, The SiC power module (4) includes a SiC power chip or a GaN power chip.

7. The on-board charging silicon nitride ceramic substrate according to claim 1, characterized in that, The lower copper layer (1) is located at the bottom and serves as a heat dissipation bonding and fixing layer. The upper copper layer (3) is located above the lower copper layer (1) and serves as a chip soldering and circuit wiring layer.

8. The on-board charging silicon nitride ceramic substrate according to claim 1, characterized in that, The silicon nitride ceramic substrate (2) is located between the upper copper layer (3) and the lower copper layer (1). The silicon nitride ceramic substrate (2) has dense columnar crystals, which can greatly improve the density and thermal conductivity of the silicon nitride ceramic substrate (2).

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