High-protection corrosion-resistant power device packaging structure and packaging method

Abstract

The invention provides a high-protection corrosion-resistant power device packaging structure. The high-protection corrosion-resistant power device packaging structure comprises a substrate; the shell is adhered to the substrate through a sealant, and the shell is provided with a step at the connection position of the power terminals at the two sides; the metal insert is arranged in the shell; the copper-clad ceramic lining plate adopts a sandwich structure of an upper copper layer, ceramic and a lower copper layer, and the copper-clad ceramic lining plate is welded on the surface of the substrate; the chip is welded on the upper surface of the copper-clad ceramic lining plate, and the chip and the copper-clad ceramic lining plate as well as the shell and the copper-clad ceramic lining plate are electrically connected through the bonding wires; the cover plate is fixedly mounted on the shell through a buckle on the back surface; and a pouring sealant is injected into the shell. According to the invention, the corrosion of the device caused by a severe environment can be effectively prevented, and the packaging production of the high-protection corrosion-resistant device is realized under the condition of not increasing additional packaging procedures and packaging equipment.

Description

Technical Field

[0001] The present invention relates to the field of power semiconductor device packaging, and in particular to a high-protection and corrosion-resistant power device packaging structure and a packaging method. Background Art

[0002] Power semiconductor devices are the core components of wind power converters to achieve energy conversion and transmission. The offshore wind power environment is generally characterized by high temperature and humidity, high salt spray concentration, and obvious dry-wet cycles. In particular, various bacteria contained in the sediments on the seabed will also produce corrosive gases such as hydrogen sulfide. These environmental factors will induce corrosion of the internal components of power devices and reduce their operational reliability. Taking potted power devices as an example, the chips, bonding wires, copper-clad ceramic linings, solder layers, substrates, silicone gels, sealants, housings, and assembly connectors inside the device are all at risk of corrosion in the sea breeze environment.

[0003] Patent No. CN202022320454 proposes to improve the corrosion resistance by electroplating nickel layer material on the surface of the shell and the shell cover and improving the sealing of the shell and the shell cover; Patent No. CN202021524463 proposes to form a sealing structure by setting sealant between the shell and the cover plate, and between the shell and the base plate, thereby slowing down the intrusion of corrosive gases.

[0004] The housing and cover of potted power devices are usually made of saturated polyester plastic. Due to the moisture permeability of the sealant itself and the pores present during the curing process of the sealant, sealing the housing and cover with sealant cannot completely isolate the intrusion of external corrosive gases, especially the corrosion of hydrogen sulfide gas to the copper components inside the device. Summary of the invention

[0005] Purpose of the invention: In order to overcome the shortcomings of the background technology, the first purpose of the present invention is to disclose a high protection and corrosion resistant power device packaging structure; The second purpose is to disclose a packaging method for the above-mentioned high-protection and corrosion-resistant power device packaging structure.

[0006] Technical solution: The high protection and corrosion resistant power device packaging structure disclosed in the present invention comprises: The substrate is made of nickel-plated copper plate; The shell is made of polybutylene terephthalate or polyphenylene sulfide plastic, and the shell is bonded to the substrate by a sealant. The shell is provided with steps at the connection positions of the power terminals on both sides; The metal inlay, made of nickel-plated copper, is placed inside the shell; The copper-clad ceramic liner adopts a sandwich structure of an upper copper layer, a ceramic layer, and a lower copper layer. The upper copper layer is electroplated with a nickel layer or the upper and lower copper layers are both electroplated with a nickel layer. The copper-clad ceramic liner is welded to the surface of the substrate. Chip, bonding wire, the chip is welded to the upper surface of the copper-clad ceramic lining board, and the chip and the copper-clad ceramic lining board, the housing and the copper-clad ceramic lining board are electrically connected through the bonding wire; The cover plate is made of polybutylene terephthalate or polyphenylene sulfide plastic, and the cover plate is fixed to the housing through a buckle on the back; The shell is filled with potting glue.

[0007] Furthermore, the copper plate thickness of the substrate ranges from 2 to 5 mm, and the nickel plating layer thickness ranges from 2 to 6 μm.

[0008] Furthermore, the height of the step is 2-4 mm, and the creepage distance is 14-16 mm.

[0009] Furthermore, the metal inlay comprises a power terminal and a signal terminal, and all interfaces are nickel plated, with a nickel layer of 2-6 μm.

[0010] Furthermore, the surface roughness of the copper layer of the copper-clad ceramic liner is Ra 2-4, and the thickness of the nickel plating layer is 2-6 μm.

[0011] Furthermore, the bonding wire is an aluminum wire or an aluminum-clad copper wire with a wire diameter of 300-500 μm; the volume proportion of the copper wire in the aluminum-clad copper wire is not less than 50%.

[0012] Furthermore, the potting glue is injected to a height not lower than the highest point of the bonding line inside the shell.

[0013] The packaging method of the above-mentioned high protection and corrosion resistant power device packaging structure comprises the following steps: S1. Welding the chip to the upper surface of the copper-clad ceramic liner, and electrically connecting the bonding wire with the chip and the copper-clad ceramic liner by ultrasonic bonding on the chip surface; S2, welding the copper-clad ceramic liner plate that has completed ultrasonic bonding to the upper surface of the substrate; S3, bonding the shell and the substrate by means of a sealant; wherein the shell is plasma cleaned before bonding; the sealant is cured at 100-140° C.; the sealant curing atmosphere is air or nitrogen; S4, electrically connecting the metal inlay in the housing to the copper-clad ceramic liner through bonding wires; S5, injecting the potting glue into the shell; wherein the potting glue is degassed in the vacuum chamber after potting; the vacuum degree of the vacuum chamber is 5-50 mbar; the injection height of the potting glue is not lower than the highest point of the bonding line inside the shell; the potting glue is cured at 100° C.-140° C.; S6. Install the cover plate to the housing through the buckles on the back.

[0014] Beneficial effects: Compared with the prior art, the advantages of the present invention are: by setting a step structure between the power terminals of the housing, the creepage distance is increased, and the insulation capacity of the device under conditions such as humid salt spray is increased; by nickel-plating each copper-containing component inside the device or using an aluminum-clad copper structure, the corrosion of the copper-containing components of the device by hydrogen sulfide gas can be effectively protected, and the generation of different copper sulfides can be isolated, thereby avoiding short circuits in the device. In addition, the present invention can realize the packaging production of highly protected and corrosion-resistant devices without adding additional packaging processes and packaging equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is the overall structure diagram of the present invention; Figure 2 This is a structural diagram of the shell of the present invention. DETAILED DESCRIPTION

[0016] The following is a detailed description in conjunction with the specific implementation methods and the accompanying drawings.

[0017] like Figure 1 and 2 The high protection and corrosion resistant power device packaging structure shown includes: Substrate 1, made of nickel-plated copper plate; The housing 2 is made of polybutylene terephthalate or polyphenylene sulfide plastic, and the housing 2 is bonded to the substrate 1 by a sealant. The housing 2 is provided with a step 3 at the connection position of the power terminals on both sides; The metal inlay is made of nickel-plated copper and is placed in the housing 1; The copper-clad ceramic liner 5 adopts a sandwich structure of an upper copper layer, a ceramic layer, and a lower copper layer. The upper copper layer is electroplated with a nickel layer or the upper and lower copper layers are both electroplated with a nickel layer. The copper-clad ceramic liner 5 is welded to the surface of the substrate 1. A chip 6 and bonding wires 7, wherein the chip 6 is welded to the upper surface of the copper-clad ceramic lining board 5, and the chip 6 and the copper-clad ceramic lining board 5, and the housing 2 and the copper-clad ceramic lining board 5 are electrically connected through the bonding wires 7; The cover plate 8 is made of polybutylene terephthalate or polyphenylene sulfide plastic, and the cover plate 8 is fixed to the housing 2 via a buckle on the back; The housing 2 is filled with potting glue.

[0018] The copper plate thickness of the substrate 1 is in the range of 2-5 mm, and the nickel plating layer thickness is in the range of 2-6 μm.

[0019] The height of the step 3 is 2-4 mm, and the creepage distance is 14-16 mm.

[0020] The metal inlay comprises a power terminal 401 and a signal terminal 402, and all interfaces are nickel plated, with a nickel layer of 2-6 μm.

[0021] The surface roughness of the copper layer of the copper-clad ceramic liner 5 is Ra 2-4, and the thickness of the nickel-plated layer is 2-6 μm.

[0022] The bonding wire 7 is an aluminum wire or an aluminum-clad copper wire, and the wire diameter is 300-500 μm; the volume proportion of the copper wire in the aluminum-clad copper wire is not less than 50%.

[0023] The injection height of the potting glue is not lower than the highest point of the bonding wire 7 inside the housing 2 .

[0024] The packaging method of the above-mentioned high protection and corrosion resistant power device packaging structure comprises the following steps: S1, welding the chip 6 to the upper surface of the copper-clad ceramic liner 5, and electrically connecting the bonding wire 7 with the chip 6 and the copper-clad ceramic liner 5 by ultrasonic bonding on the surface of the chip 6; S2, welding the copper-clad ceramic liner 5 after ultrasonic bonding to the upper surface of the substrate 1; S3, bonding the housing 2 and the substrate 1 by means of a sealant; wherein the housing 2 is plasma cleaned before bonding; the sealant is cured at 100-140° C.; the sealant curing atmosphere is air or nitrogen; S4, electrically connecting the metal inlay in the housing 2 and the copper-clad ceramic liner 5 through the bonding wire 7; S5, injecting the potting glue into the housing 2; wherein the potting glue is degassed in a vacuum chamber after potting; the vacuum degree of the vacuum chamber is 5-50 mbar; the injection height of the potting glue is not lower than the highest point of the bonding line 7 inside the housing 2; the potting glue is cured at 100° C.-140° C.; S6. Install the cover plate 8 to the housing 2 via the buckles on the back.

[0025] Take a power device with a voltage of 1700V and a current of 600A as an example.

[0026] The above high protection and corrosion resistant power device packaging structure includes: The substrate 1 is a nickel-plated copper plate with a thickness of 3 mm and a nickel-plated layer thickness of 4 μm.

[0027] The shell 2 is made of polybutylene terephthalate and is bonded to the substrate 1 by means of a sealant. The shell 2 is provided with a step 3 at the connection position of the power terminals on both sides, with a height of 3 mm and a creepage distance of 15 mm.

[0028] The metal inlay is made of nickel-plated copper material and is placed in the housing 1. The metal inlay includes a power terminal 401 and a signal terminal 402. All interfaces are nickel-plated, and the nickel layer is 4 μm.

[0029] The copper-clad ceramic liner 5 adopts a sandwich structure of an upper copper layer, ceramic, and a lower copper layer. The upper and lower copper layers are both electroplated with nickel layers. The surface roughness of the copper layer is Ra 3, and the thickness of the nickel plating layer is 4 μm. The copper-clad ceramic liner 5 is welded to the surface of the substrate 1.

[0030] Chip 6, bonding wire 7, the chip 6 is welded to the upper surface of the copper-clad ceramic liner 5, and the chip 6 and the copper-clad ceramic liner 5, the housing 2 and the copper-clad ceramic liner 5 are electrically connected through the bonding wire 7. The bonding wire 7 is an aluminum-clad copper wire with a wire diameter of 400 μm; the volume of the copper wire in the aluminum-clad copper wire accounts for 60%.

[0031] The cover plate 8 is made of polybutylene terephthalate and is fixed to the housing 2 via buckles on the back; The housing 2 is filled with potting glue, and the injection height of the potting glue is higher than the highest point of the bonding wire 7 inside the housing 2 .

[0032] When packaging: The chip 6 is welded to the upper surface of the copper-clad ceramic liner 5, and the bonding wire 7 is electrically connected to the chip 6 and the copper-clad ceramic liner 5 by ultrasonic bonding on the surface of the chip 6; The copper-clad ceramic liner 5 after ultrasonic bonding is welded to the upper surface of the substrate 1; The shell 2 and the substrate 1 are bonded together by a sealant; wherein the shell 2 is plasma cleaned before bonding; the sealant is cured at 120° C.; the sealant curing atmosphere is nitrogen; The metal inlay in the housing 2 is electrically connected to the copper-clad ceramic liner 5 through bonding wires 7; The potting glue is injected into the housing 2; wherein the potting glue is degassed in a vacuum chamber after potting; the vacuum degree of the vacuum chamber is 40 mbar; the injection height of the potting glue is higher than the highest point of the bonding line 7 inside the housing 2; the potting glue is cured at 120°C; The cover plate 8 is mounted on the housing 2 via the buckles on the back.

[0033] Gas corrosion test on packaged devices: Test conditions: hydrogen sulfide gas content 25ppm, temperature 60℃, humidity 80%RH, voltage 800V, test time 720 hours. After the test, no copper sulfide dendrites grew on the device surface, and the device passed the static test and insulation test retest.

Claims

1. A high protection and corrosion resistant power device packaging structure, characterized in that: include: The substrate (1) is a nickel-plated copper plate; The shell (2) is made of polybutylene terephthalate or polyphenylene sulfide plastic, the shell (2) is bonded to the substrate (1) by means of a sealant, and the shell (2) is provided with a step (3) at the connection position of the power terminals on both sides; A metal inlay made of nickel-plated copper material is placed inside the housing (1); The copper-clad ceramic liner (5) adopts a sandwich structure of an upper copper layer, ceramic, and a lower copper layer, the surface of the upper copper layer is electroplated with a nickel layer, or the surfaces of the upper and lower copper layers are both electroplated with nickel layers, and the copper-clad ceramic liner (5) is welded to the surface of the substrate (1); A chip (6) and a bonding wire (7), wherein the chip (6) is welded to the upper surface of the copper-clad ceramic lining (5), and the chip (6) and the copper-clad ceramic lining (5), and the housing (2) and the copper-clad ceramic lining (5) are electrically connected via the bonding wire (7); The cover plate (8) is made of polybutylene terephthalate or polyphenylene sulfide plastic, and the cover plate (8) is fixedly mounted to the housing (2) via a buckle on the back side; The shell (2) is filled with potting glue.

2. The high protection and corrosion resistant power device packaging structure according to claim 1, characterized in that: The copper plate thickness of the substrate (1) is in the range of 2-5 mm, and the nickel plating layer thickness is in the range of 2-6 μm.

3. The high protection and corrosion resistant power device packaging structure according to claim 1, characterized in that: The height of the step (3) is 2-4 mm, and the creepage distance is 14-16 mm.

4. The high protection and corrosion resistant power device packaging structure according to claim 1, characterized in that: The metal inlay comprises a power terminal (401) and a signal terminal (402), and all interfaces are nickel-plated, with the nickel layer having a thickness of 2-6 μm.

5. The high protection and corrosion resistant power device packaging structure according to claim 1, characterized in that: The surface roughness of the copper layer of the copper-clad ceramic lining plate (5) is Ra 2-4, and the thickness of the nickel-plated layer is 2-6 μm.

6. The high protection and corrosion resistant power device packaging structure according to claim 1, characterized in that: The bonding wire (7) is an aluminum wire or an aluminum-clad copper wire, and has a wire diameter of 300-500 μm; the volume proportion of the copper wire in the aluminum-clad copper wire is not less than 50%.

7. The high protection and corrosion resistant power device packaging structure according to claim 1, characterized in that: The potting glue is injected to a height not lower than the highest point of the bonding line (7) inside the housing (2).

8. The packaging method of the high protection and corrosion resistant power device packaging structure according to claim 1, characterized in that: The following steps are involved: S1, welding the chip (6) to the upper surface of the copper-clad ceramic liner (5), and electrically connecting the bonding wire (7) with the chip (6) and the copper-clad ceramic liner (5) by ultrasonic bonding on the surface of the chip (6); S2, welding the copper-clad ceramic liner (5) that has completed ultrasonic bonding to the upper surface of the substrate (1); S3, bonding the shell (2) and the substrate (1) by means of a sealant; wherein the shell (2) is plasma cleaned before bonding; the sealant is cured at 100-140° C.; the sealant curing atmosphere is air or nitrogen; S4, electrically connecting the metal inlay in the housing (2) and the copper-clad ceramic liner (5) via bonding wires (7); S5, injecting a potting glue into the interior of the housing (2); wherein the potting glue is degassed in a vacuum chamber after potting; the vacuum degree of the vacuum chamber is 5-50 mbar; the injection height of the potting glue is not lower than the highest point of the bonding line (7) inside the housing (2); and the potting glue is cured at 100° C.-140° C.; S6. The cover plate (8) is mounted on the housing (2) by means of the buckles on the back.

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