Welding packaging process of semiconductor device assembly

Abstract

The invention discloses a welding packaging process of a semiconductor device assembly, which belongs to the technical field of semiconductor device preparation, and comprises the following steps: brushing a layer of soldering paste on the upper surface of an aluminum bottom plate; the size of the copper-coated ceramic wafer is reduced; assembling the plurality of single-tube devices, the plurality of copper-clad ceramic chips and the aluminum bottom plate to obtain a single-tube assembly; the single pipe assembly is put into a high-temperature welding furnace for welding treatment; after welding is completed, the single pipe assembly is taken out and cleaned; dam glue is applied to the periphery of the aluminum bottom plate and cured; the space formed by the solidified box dam glue is filled with insulation glue; and carrying out defoaming treatment on the potting insulation paste. By adding the insulation paste, the problem of insufficient creepage distance between the single-tube heat dissipation and the aluminum bottom plate is solved, and the DBC size is reduced, so that the size of the whole assembly is reduced; and through innovation of the welding treatment process, the performance in the aspects of preventing device layering, reducing the welding void rate and improving the welding spot microstructure quality and the overall product reliability is remarkably improved.

Description

Technical Field

[0001] This invention belongs to the technical field of semiconductor device fabrication, and specifically relates to a welding and packaging process for semiconductor device components. Background Technology

[0002] Semiconductor devices are devices with special conductivity properties; their conductivity changes under different conditions, thereby enabling current control. This characteristic makes semiconductor devices a core component of modern electronic technology. Semiconductor devices control current by changing the conductivity of the semiconductor material under different conditions. For example, under conditions such as high voltage or high temperature, the semiconductor material will change from an insulating state to a conductive state, thereby enabling the circuit to be switched on or off. Types include transistors: as the most basic semiconductor devices, transistors play a role in amplification and switching in circuits; diodes: having unidirectional conductivity, they are commonly used for rectification, voltage regulation, and signal modulation; and field-effect transistors (MOSFETs): having high current drive capability and low switching losses, they are widely used in power management and other fields.

[0003] Due to the need to handle various operating conditions, several semiconductor devices are assembled into a single component. Currently, the packaging process for semiconductor device components typically involves soldering a single semiconductor device, a DBC (copper-clad ceramic wafer), and a base plate for direct use. This approach, considering the electrical safety clearances and creepage distances between components, results in an overly large exposed DBC ceramic layer, leading to an overall larger package size and increased risk of ceramic breakage. For example, a typical 600V component requires at least a 2.6mm creepage distance from the DBC, necessitating a minimum component length of 92cm. If the device needs to withstand 1200V, a 6mm creepage distance is required, with a minimum component length of 110mm, significantly impacting application integration design. Summary of the Invention

[0004] The purpose of this invention is to address the aforementioned shortcomings in the prior art by providing a welding and packaging process for semiconductor device components, thereby solving the problem that an excessively large exposed ceramic dimension in the DBC design leads to an excessively large overall component packaging size.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A welding and packaging process for a semiconductor device assembly includes the following steps: S1. Apply a layer of solder paste to the surface of the aluminum base plate; S2. Reduce the size of the copper-clad ceramic sheet according to the size of the single tube device, and brush a layer of solder paste on the copper-clad ceramic sheet; S3. Assemble multiple single-tube devices, multiple copper-clad ceramic sheets, and an aluminum base plate to obtain a single-tube assembly; S4. Place the single-tube assembly into a high-temperature welding furnace for welding. S5. After welding is completed, remove the single tube assembly and clean it; S6. Apply damming adhesive around the aluminum base plate and allow it to cure. S7. Fill the space formed by the cured damming adhesive with insulating adhesive; S8. Degas the potting insulating adhesive.

[0006] Furthermore, in S2, each single tube device corresponds to a copper-clad ceramic sheet. The single tube device is placed on the copper-clad ceramic sheet, and the distance of the blank area of ​​the copper-clad ceramic sheet is reduced until the blank distance at the edge of the copper-clad ceramic sheet is reduced to 0.2mm-0.3mm.

[0007] Furthermore, step S3 includes the following sub-steps: S31. Place the aluminum base plate into the reflow oven tray; S32. Place the copper-clad ceramic sheet positioning fixture on the aluminum base plate, and make sure the aluminum base plate is in contact with the copper-clad ceramic sheet positioning fixture. S33. Place the copper-clad ceramic sheets into the copper-clad ceramic sheet positioning fixture in sequence; S34. Remove the copper-clad ceramic sheet positioning fixture; S35. Snap the single tube positioning clamp onto the copper-clad ceramic sheet; S36. Place the single tube component on the single tube positioning fixture, ensuring full contact between the single tube component and the solder paste surface of the copper-clad ceramic sheet. Then remove the single tube positioning fixture to complete the assembly of the single tube assembly.

[0008] Furthermore, in step S4, the single-tube assembly is placed in a high-temperature welding furnace for welding, including the following stages: During the preheating stage, the reflow oven tray containing the single tube assembly is placed into the high-temperature welding furnace, the heating rate is controlled at 1-3℃ / s, the temperature is maintained at 150-200℃, and the preheating time is 70-120s. During the reflux stage, the reflux temperature is 205-225℃, and the reflux time is 150-240s; During the vacuuming stage, the high-temperature welding furnace is evacuated until the vacuum level reaches below 1 mbar. During the cooling stage, zoned cooling is used to cool the single-tube components at a rate of 1-4℃ / s.

[0009] Furthermore, during the preheating stage, when the temperature reaches 120°C, a controllable directional airflow disturbance is introduced into the high-temperature soldering furnace and applied to the area above the reflow oven tray, directional blowing solder joints, to accelerate the removal of solvents and low-boiling-point volatiles from the solder paste.

[0010] Furthermore, during the reflow stage, the temperature inside the high-temperature welding furnace is collected in real time. After the solder has completely melted and held for 30-50 seconds, a pre-vacuum process is initiated to gradually reduce the pressure inside the high-temperature welding furnace.

[0011] Furthermore, during the vacuuming phase, the pressure inside the high-temperature welding furnace is rapidly reduced to 10-20 mbar within 10-15 seconds, and then the pressure is steadily and continuously reduced to a vacuum level of less than 1 mbar over a period of 30-60 seconds, and this vacuum level is maintained for 60-120 seconds.

[0012] Furthermore, during the vacuuming stage, and for a period of time when the vacuum level is less than 1 mbar, a piezoelectric ceramic actuator is used to apply vibrations with a frequency of 100-500 Hz and an amplitude of less than 10 micrometers to the bottom of the reflow oven tray, with the vibration direction perpendicular to the solder joint.

[0013] Furthermore, during the cooling stage, the cooling rate is 1.0-1.8℃ / s for densely populated solder joint areas and 2.5-3.5℃ / s for sparsely populated solder joint areas.

[0014] Furthermore, in S6, the width of the dammed adhesive is 1mm greater than the outer perimeter of the copper-clad ceramic sheet, the height of the dammed adhesive exceeds the copper-clad ceramic sheet after welding by 1mm, and the dammed adhesive is left to cure at room temperature for 1-2 hours after application.

[0015] The welding and packaging process for semiconductor device components provided by this invention has the following beneficial effects: 1. This invention compensates for the insufficient creepage distance between the heat dissipation of the single tube (semiconductor device) and the aluminum base plate by adding insulating adhesive, thereby reducing the DBC size and thus reducing the overall component size.

[0016] 2. By reducing the size of the DBC, this invention can shorten the edge ceramic of the DBC to the minimum blank size for 600V industrial applications compared to traditional solutions, thus reducing the size of a single DBC by 4.8mm.

[0017] 3. Through innovation in welding processing technology, this invention significantly improves the performance of welding technology in preventing device delamination, reducing weld voids, improving the microstructure quality of solder joints, and enhancing overall product reliability. Attached Figure Description

[0018] Figure 1 This is a flowchart of the welding and packaging process for semiconductor device components according to an embodiment of the present invention. Detailed Implementation

[0019] The specific embodiments of the present invention are described below to enable those skilled in the art to understand the present invention. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0020] The semiconductor device assembly welding and packaging process in this embodiment effectively solves the problem that an excessively large exposed DBC ceramic size leads to an overly large overall assembly package size by reducing the DBC size and increasing the amount of insulating adhesive. (Refer to...) Figure 1 Specifically, it includes the following: S1. Apply a layer of solder paste to the surface of the aluminum base plate; S2. Reduce the size of the copper-clad ceramic sheet according to the size of the single tube device, and brush a layer of solder paste on the copper-clad ceramic sheet; In one specific embodiment, this embodiment preferably uses three single-tube devices, each single-tube device corresponding to a copper-clad ceramic sheet (DBC). That is, three positions are set on the aluminum base plate, one DBC is placed at each position, and one single-tube device is placed on each DBC, thus forming a single-tube assembly. The detailed installation process is shown in S3.

[0021] In one specific embodiment, a single tube device is placed on a copper-clad ceramic sheet, and the distance of the blank area of ​​the copper-clad ceramic sheet is reduced until the blank distance at the edge of the copper-clad ceramic sheet is reduced to 0.2mm-0.3mm. This blank distance at the edge represents the shortest straight-line distance from the edge of the single tube to the edge of the copper-clad ceramic sheet.

[0022] S3. Assemble multiple single-tube devices, multiple copper-clad ceramic sheets, and an aluminum base plate to obtain a single-tube assembly, which specifically includes the following steps: S31. Place the aluminum base plate into the reflow oven tray; S32. Place the copper-clad ceramic sheet positioning fixture on the aluminum base plate, and make sure the aluminum base plate is in contact with the copper-clad ceramic sheet positioning fixture. S33. Place the copper-clad ceramic sheets into the copper-clad ceramic sheet positioning fixture in sequence; S34. Remove the copper-clad ceramic sheet positioning fixture; S35. Snap the single tube positioning clamp onto the copper-clad ceramic sheet; S36. Place the single tube component on the single tube positioning fixture, ensuring full contact between the single tube component and the solder paste surface of the copper-clad ceramic sheet. Then remove the single tube positioning fixture to complete the assembly of the single tube assembly.

[0023] S4. The single-tube assembly is placed in a high-temperature welding furnace for welding, which specifically includes the following stages: During the preheating stage, the reflow oven tray containing the single tube assembly is placed into the high-temperature welding furnace, the heating rate is controlled at 1-3℃ / s, the temperature is maintained at 150-200℃, and the preheating time is 70-120s. In one specific embodiment, during the preheating stage, when the temperature reaches 120°C, a controllable directional airflow disturbance is introduced into the high-temperature welding furnace, and this airflow disturbance is applied to the area above the reflow oven tray, specifically to the directional blow-weld joint area.

[0024] The airflow disturbance can be achieved by setting a rotatable nozzle in the high-temperature soldering furnace. An inert gas is selected to accelerate the discharge of solvents and low-boiling-point volatiles in the solder paste, while enhancing the wetting and spreading effect of the flux on the solder pad surface.

[0025] During the reflux stage, the reflux temperature is 205-225℃, and the reflux time is 150-240s; In one specific embodiment, during the reflow stage, the temperature inside the high-temperature welding furnace is monitored in real time. After the solder has completely melted and held for 30-50 seconds, a pre-vacuum treatment is initiated to gradually reduce the pressure inside the high-temperature welding furnace. This design allows for vacuuming to begin when the solder is completely melted and has optimal fluidity (mid-reflow). Compared to the traditional method of vacuuming after reflow, air bubbles are more easily extracted when the internal pressure of the molten solder is still high and its fluidity is optimal. This lays a more favorable foundation for more thorough air bubble removal in the subsequent vacuuming stage, significantly reducing the void ratio.

[0026] During the vacuuming stage, the high-temperature welding furnace is evacuated until the vacuum level reaches below 1 mbar. In one specific embodiment, during the vacuuming phase, the pressure inside the high-temperature welding furnace is rapidly reduced to 10-20 mbar within the first 10-15 seconds, and then steadily and continuously reduced to a vacuum level of less than 1 mbar over a period of 30-60 seconds, maintaining this vacuum level for 60-120 seconds. This gradual pressure reduction avoids the molten solder from boiling violently or "splattering" due to a sudden pressure drop, preventing the formation of new bubbles or disturbance of existing solder joints. A steady pressure reduction is more conducive to the stable, continuous precipitation and removal of bubbles.

[0027] In one specific embodiment, during the vacuuming phase, and for a duration maintaining a vacuum level of less than 1 mbar, a piezoelectric ceramic actuator is used to apply vibrations at a frequency of 100-500 Hz and an amplitude of less than 10 micrometers to the bottom of the reflow oven tray, with the vibration direction perpendicular to the solder joint. This micro-vibration effectively breaks down the interfacial tension between the bubbles and the liquid metal, loosening and releasing small microbubbles adsorbed within the pads, device leads, or solder, making them easier to remove under vacuum. This is particularly effective in removing stubborn bubbles at the micrometer or even submicrometer scale, further significantly reducing the microvoid rate and improving the density and reliability of the solder joint.

[0028] During the cooling stage, zoned cooling is used to cool the single-tube assembly, with a cooling rate of 1-4℃ / s. During the cooling phase, the cooling rate is 1.0-1.8℃ / s for areas with dense solder joints and 2.5-3.5℃ / s for areas with sparse solder joints. This differentiated cooling strategy, tailored to the thermal stress sensitivity of solder joints and components in different areas, significantly improves the overall reliability of the product's welded structure while ensuring overall cooling efficiency.

[0029] S5. After welding, remove the single tube assembly, clean it in the cleaning solution, and blow it dry.

[0030] S6. Apply damming adhesive around the aluminum base plate and allow it to cure. Specifically, the width of the dammed adhesive is 1mm wider than the outer dimensions of the copper-clad ceramic sheet, and the height of the dammed adhesive exceeds the copper-clad ceramic sheet after welding by 1mm. After applying the dammed adhesive, allow it to cure at room temperature for 1-2 hours. Features of the damming adhesive: It is a paste-like substance that does not drip, has good adhesion, good continuous thermal stability (-55-200°C), and good high-temperature electrical insulation properties.

[0031] S7. Fill the space formed by the cured damming adhesive with insulating adhesive; The insulating adhesive must be a low-viscosity, environmentally friendly fluid with good adhesion to various circuit boards and no corrosion to molding compounds; its breakdown strength must be ≥20KV / mm; its dielectric constant must be 3±0.5; and its surface resistivity must be ≥10. 14 It has a strength of Ω·cm and exhibits good sustained thermal stability.

[0032] S8. Degas the potting insulating adhesive.

[0033] Although specific embodiments of the invention have been described in detail with reference to the accompanying drawings, this should not be construed as limiting the scope of protection of this patent. Various modifications and variations that can be made by a person skilled in the art without inventive effort within the scope described in the claims still fall within the scope of protection of this patent.

Claims

1. A welding and packaging process for a semiconductor device assembly, characterized in that, Includes the following steps: S1. Apply a layer of solder paste to the surface of the aluminum base plate; S2. Reduce the size of the copper-clad ceramic sheet according to the size of the single tube device, and brush a layer of solder paste on the copper-clad ceramic sheet; S3. Assemble multiple single-tube devices, multiple copper-clad ceramic sheets, and an aluminum base plate to obtain a single-tube assembly; S4. Place the single-tube assembly into a high-temperature welding furnace for welding. S5. After welding is completed, remove the single tube assembly and clean it; S6. Apply damming adhesive around the aluminum base plate and allow it to cure. S7. Fill the space formed by the cured damming adhesive with insulating adhesive; S8. Degas the potting insulating adhesive.

2. The welding and packaging process for semiconductor device components according to claim 1, characterized in that, In step S2, each single-tube device corresponds to a copper-clad ceramic sheet. The single-tube device is placed on the copper-clad ceramic sheet, and the distance of the blank area of ​​the copper-clad ceramic sheet is reduced until the blank distance at the edge of the copper-clad ceramic sheet is reduced to 0.2mm-0.3mm.

3. The welding and packaging process for semiconductor device components according to claim 1, characterized in that, S3 includes the following steps: S31. Place the aluminum base plate into the reflow oven tray; S32. Place the copper-clad ceramic sheet positioning fixture on the aluminum base plate, and make sure the aluminum base plate is in contact with the copper-clad ceramic sheet positioning fixture. S33. Place the copper-clad ceramic sheets into the copper-clad ceramic sheet positioning fixture in sequence; S34. Remove the copper-clad ceramic sheet positioning fixture; S35. Snap the single tube positioning clamp onto the copper-clad ceramic sheet; S36. Place the single tube component on the single tube positioning fixture, ensuring full contact between the single tube component and the solder paste surface of the copper-clad ceramic sheet. Then remove the single tube positioning fixture to complete the assembly of the single tube assembly.

4. The welding and packaging process for semiconductor device components according to claim 1, characterized in that, In step S4, the single-tube assembly is placed in a high-temperature welding furnace for welding. Includes the following stages: During the preheating stage, the reflow oven tray containing the single tube assembly is placed into the high-temperature welding furnace, the heating rate is controlled at 1-3℃ / s, the temperature is maintained at 150-200℃, and the preheating time is 70-120s. During the reflux stage, the reflux temperature is 205-225℃, and the reflux time is 150-240s; During the vacuuming stage, the high-temperature welding furnace is evacuated until the vacuum level reaches below 1 mbar. During the cooling stage, zoned cooling is used to cool the single-tube components at a rate of 1-4℃ / s.

5. The welding and packaging process for semiconductor device components according to claim 4, characterized in that: During the preheating stage, when the temperature reaches 120°C, a controllable directional airflow disturbance is introduced into the high-temperature soldering furnace and applied to the area above the reflow oven tray, directional blowing solder joints, to accelerate the removal of solvents and low-boiling-point volatiles from the solder paste.

6. The welding and packaging process for semiconductor device components according to claim 4, characterized in that: During the reflow stage, the temperature inside the high-temperature welding furnace is collected in real time. After the solder has completely melted and is held for 30-50 seconds, the pre-vacuum treatment is started to gradually reduce the pressure inside the high-temperature welding furnace.

7. The welding and packaging process for semiconductor device components according to claim 4, characterized in that: During the vacuuming phase, the pressure inside the high-temperature welding furnace is rapidly reduced to 10-20 mbar within 10-15 seconds, and then the pressure is steadily and continuously reduced to a vacuum level of less than 1 mbar over 30-60 seconds, and this vacuum level is maintained for 60-120 seconds.

8. The welding and packaging process for semiconductor device components according to claim 7, characterized in that: During the vacuuming stage, and for a period of time when the vacuum level is less than 1 mbar, a piezoelectric ceramic actuator is used to apply vibrations with a frequency of 100-500 Hz and an amplitude of less than 10 micrometers to the bottom of the reflow oven tray, with the vibration direction perpendicular to the solder joint.

9. The welding and packaging process for semiconductor device components according to claim 4, characterized in that: During the cooling stage, the cooling rate is 1.0-1.8℃ / s for densely populated solder joint areas and 2.5-3.5℃ / s for sparsely populated solder joint areas.

10. The welding and packaging process for semiconductor device components according to claim 1, characterized in that: In step S6, the width of the dammed adhesive is 1mm greater than the outer perimeter of the copper-clad ceramic sheet, and the height of the dammed adhesive exceeds the copper-clad ceramic sheet after welding by 1mm. After applying the dammed adhesive, it is left to cure at room temperature for 1-2 hours.

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