A tooling for interconnecting substrates and a substrate welding method with precise positioning

Abstract

The present invention provides a tooling for interconnecting substrates and a precisely positioned substrate welding method, the substrate welding method comprising the following steps: S1. placing the substrate in the corresponding acupuncture point in the tooling for interconnecting substrates, and fixing the substrate by adsorption through the tooling; S2. bonding the adjacent substrates under the adsorption and fixation of the tooling to complete the interconnection between the substrates; S3. fixing the substrate welding fixture at a selected position on the heat dissipation base plate, placing the bonded substrate into the welding fixture to weld the substrate to the heat dissipation base plate. The precisely positioned substrate welding method can achieve precise control of the spacing between the two substrates on the heat dissipation base plate, and reduce the failure caused by the molten flow of the solder causing the substrates to flow to the middle and collide with each other during the welding process.

Description

Technical Field

[0001] The present invention belongs to the technical field of IGBT module packaging, and in particular relates to a tooling for interconnecting substrates and a precise positioning substrate welding method. Background Art

[0002] The packaging of power chips such as IGBT usually uses DBC as the substrate for electrical layout and interconnection. A power module is usually composed of multiple DBCs, which need to be soldered to a heat sink during packaging. At present, the conventional packaging sequence is: first mount the chip on the DBC, then solder the chip to the DBC, then bond the copper clad on the surface of the chip to the DBC, mount the DBC with the chip soldered to the heat sink, and then solder the entire system, assemble the frame, bond the frame, and fill the glue to complete the packaging and test it.

[0003] When welding the DBC to the heat dissipation base plate, a clamp is required to fix the DBC. The Chinese patent document with publication number CN218452728 U discloses a welding jig, including a pressure plate, a partition is provided on the pressure plate, and the partition separates the pressure plate into two mounting holes. When the DBC is welded, two DBCs are placed in the mounting holes to position the DBC. The jig ensures that the long-side dimension of the DBC does not move through the middle partition. However, considering the deformation of the base plate during heating and welding and after cooling, in order to facilitate disassembly and positioning, the welding jig usually leaves a certain tolerance, and the arc of the pre-bend of the heat dissipation base plate causes the middle partition to tilt. During the welding process, the molten flow of the solder causes the DBC to shift on the heat dissipation base plate, and the tilted partition cannot well guarantee the limiting effect on the DBC, which causes the relative position between adjacent DBCs to shift, and the spacing between the two DBCs cannot be accurately controlled, and even causes adjacent DBCs to flow to the middle and collide with each other, causing difficulties or failures in subsequent processing. Summary of the invention

[0004] The technical problem solved by the present invention is to provide a tooling for interconnecting substrates and a substrate welding method with precise positioning, which can realize precise control of the distance between two substrates on a heat dissipation base plate, and reduce the failure caused by the molten flow of solder during welding, which causes the substrates to flow to the middle and collide with each other.

[0005] In order to solve the above problems, an object of the present invention is to provide a tool for interconnecting substrates, comprising:

[0006] A vacuum adsorption platform, wherein a plurality of acupuncture points are provided on the vacuum adsorption platform, wherein the acupuncture points are suitable for placing substrates and limiting the positions of the substrates; the arrangement mode and arrangement interval of the acupuncture points are consistent with the arrangement mode and arrangement interval of the interconnected substrates to be formed; and a plurality of vacuum holes are provided in each of the acupuncture points;

[0007] A vacuum pipeline is connected to the vacuum hole, and the vacuum pipeline is used to evacuate the vacuum hole to adsorb and fix the substrate in the acupoint.

[0008] Preferably, each of the acupuncture points is provided with 12 to 48 vacuum holes; the vacuum holes are arranged at equal intervals.

[0009] Preferably, at least 6 groups of acupoints are provided on the vacuum adsorption platform, each group includes 2 acupoints, and the distance between the 2 acupoints in each group is 2-5 cm.

[0010] Another object of the present invention is to provide a substrate welding method with precise positioning, comprising the following steps:

[0011] S1. placing the substrate in the corresponding acupuncture points in the tooling for interconnecting the substrates, and fixing the substrate by adsorption through the tooling;

[0012] S2. Under the adsorption and fixation of the tooling, bonding is performed between adjacent substrates to complete the interconnection between the substrates;

[0013] S3. Fix the substrate welding fixture at a selected position on the heat dissipation base plate, and place the bonded substrate into the welding fixture to weld the substrate to the heat dissipation base plate.

[0014] Preferably, the substrate is one of a DBC substrate, an AMB substrate and a ZTA substrate.

[0015] Preferably, aluminum wire or copper wire is used for bonding between adjacent substrates; the purity of the bonding wire is greater than 99.99%; and the wire diameter of the bonding wire is 8-20 mil.

[0016] Preferably, before step S2, the process further includes soldering the chip to the substrate and bonding the chip to the copper clad on the surface of the substrate under the adsorption and fixation of the tooling.

[0017] Preferably, step S3 specifically includes: fixing the substrate welding fixture at a selected position on the heat dissipation base plate, placing the welding sheet on the heat dissipation base plate and in the welding fixture, using a vacuum suction nozzle to suck the bonded substrate and transfer it to the welding fixture, welding the substrate to the heat dissipation base plate, and then assembling the frame, bonding the frame, and pouring glue to complete the packaging.

[0018] Preferably, the bonding between the substrates and the bonding between the substrate and the heat dissipation base plate are completed by a bonding machine; the bonding method is one of cold pressure ultrasonic welding, ultrasonic linear welding, ultrasonic torque welding, and hot pressure ultrasonic welding.

[0019] Preferably, the welding fixture is made of graphite or metal.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The tooling of the present invention is used for bonding and interconnecting two or more substrates. When in use, each substrate is placed in a hole on a vacuum adsorption platform, and a vacuum pipeline is connected to a vacuum device. The substrate is adsorbed and fixed in the hole through the negative pressure of the vacuum pipeline. The substrate is limited by the hole, and bonding and interconnection between the two substrates are performed while ensuring the spacing between two adjacent substrates.

[0022] The precise positioning substrate welding method of the present invention first uses a tool to position the two substrates, bonds and interconnects the two substrates, and then welds the interconnected two substrates to the heat dissipation base plate. On the one hand, the spacing between the two substrates is controlled by the fixing effect of the bonding wire, thereby realizing precise control of the spacing between the two substrates on the heat dissipation base plate, reducing the failure caused by the molten flow of the solder during the welding process causing the substrates to flow to the middle and collide with each other; on the other hand, by fixing the two substrates with the bonding wire, there is no need to set a partition on the substrate welding fixture, which can simplify the structure of the welding fixture, and there is no need to customize a welding fixture with a complex structure according to the number and structure of the substrates; this method can weld the upper and lower bridge substrates to the heat dissipation base plate at the same time, improving efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic structural diagram of a vacuum adsorption platform in a tooling for interconnecting substrates according to Embodiment 1 of the present invention;

[0024] Figure 2 It is a schematic diagram of the structure of the acupuncture points in the tooling for interconnecting substrates according to Embodiment 1 of the present invention;

[0025] Figure 3 is a schematic diagram of the bonding between the chip and the DBC substrate after the bonding is completed in Example 2 of the present invention;

[0026] Figure 4 is a schematic diagram after the bonding interconnection between DBC substrates is completed in Example 2 of the present invention;

[0027] Figure 5 is a schematic diagram of DBC3 placed in a welding fixture in Example 2 of the present invention;

[0028] Figure 6 It is a schematic diagram of the structure after the heat dissipation base plate, DBC substrate and fixture are placed in Example 2 of the present invention.

[0029] Among them: 1-vacuum adsorption platform; 2-acupoint; 3-vacuum hole; 4-chip; 5-heat dissipation base plate; 6-soldering piece; 7-soldering fixture; 8-DBC substrate upper bridge; 9-DBC substrate lower bridge. DETAILED DESCRIPTION

[0030] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solution of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0031] An object of an embodiment of the present invention is to provide a tool for interconnecting substrates, comprising:

[0032] A vacuum adsorption platform, wherein a plurality of acupuncture points are provided on the vacuum adsorption platform, wherein the acupuncture points are suitable for placing substrates and limiting the positions of the substrates; the arrangement mode and arrangement interval of the acupuncture points are consistent with the arrangement mode and arrangement interval of the interconnected substrates to be formed; and a plurality of vacuum holes are provided in each of the acupuncture points;

[0033] A vacuum pipeline is connected to the vacuum hole, and the vacuum pipeline is used to evacuate the vacuum hole to adsorb and fix the substrate in the acupoint.

[0034] The tooling of the embodiment of the present invention is used for bonding and interconnecting two or more substrates. When in use, each substrate is placed in a hole on a vacuum adsorption platform, and a vacuum pipeline is connected to a vacuum device. The substrate is adsorbed and fixed in the hole through the negative pressure of the vacuum pipeline. The substrate is limited by the hole, and bonding and interconnection between the two substrates are performed while ensuring the spacing between two adjacent substrates.

[0035] In some embodiments, the number of vacuum holes in each acupoint can be set according to the size of the acupoint. Preferably, each acupoint is provided with 12 to 48 vacuum holes; and the plurality of vacuum holes are arranged at equal intervals.

[0036] In some embodiments, the number of acupoints on the vacuum adsorption platform can be set according to actual needs, and multiple groups of acupoints can be set to perform batch bonding and interconnection of multiple substrates. Preferably, at least 6 groups of acupoints are provided on the vacuum adsorption platform, each group includes 2 acupoints, and the spacing between the 2 acupoints in each group is 2-5 cm. This setting is suitable for bonding and interconnecting two substrates, and 6 groups of substrates can be bonded in batches. The spacing between the 2 acupoints in each group can be designed according to the design requirements.

[0037] Another object of the present invention is to provide a substrate welding method with precise positioning, comprising the following steps:

[0038] S1. placing the substrate in the corresponding acupuncture points in the tooling for interconnecting the substrates, and fixing the substrate by adsorption through the tooling;

[0039] S2. Under the adsorption and fixation of the tooling, bonding is performed between adjacent substrates to complete the interconnection between the substrates;

[0040] S3. Fix the substrate welding fixture at a selected position on the heat dissipation base plate, and place the bonded substrate into the welding fixture to weld the substrate to the heat dissipation base plate.

[0041] At present, the conventional substrate welding method is to first mount the chip on the substrate, then weld the chip and the substrate, and then bond the copper clad on the surface of the chip to the substrate, and then mount the substrate with the chip welded on a heat dissipation base plate provided with a fixture, and a partition is provided between the two substrates on the fixture, and the distance between the two substrates is controlled by the partition, and then the welding of the entire system and the bonding between the substrates are performed. That is, the substrate and the heat dissipation base plate are welded first, and then the bonding and interconnection between the substrates are performed. However, the heat dissipation base plate is usually pre-bent to a certain arc, which makes the partition between the substrates on the fixture warp up. When the substrate and the heat dissipation base plate are welded, the molten flow of the solder causes the substrate to shift on the heat dissipation base plate. The warped partition cannot accurately control the position of the two substrates, so that the relative position between adjacent substrates is offset, and the distance between the two substrates cannot be accurately controlled.

[0042] The precise positioning substrate welding method of the embodiment of the present invention first uses a tool to position the two substrates, bonds and interconnects the two substrates, and then welds the interconnected two substrates to the heat dissipation base plate. On the one hand, the spacing between the two substrates is controlled by the fixing effect of the bonding wire, thereby realizing precise control of the spacing between the two substrates on the heat dissipation base plate, reducing the failure caused by the molten flow of the solder during the welding process, which causes the substrates to flow to the middle and collide with each other; on the other hand, by fixing the two substrates with the bonding wire, there is no need to set a partition on the substrate welding fixture, which can simplify the structure of the welding fixture, and there is no need to customize a welding fixture with a complex structure according to the number and structure of the substrates; this method can weld the upper and lower bridge substrates to the heat dissipation base plate at the same time, improving efficiency.

[0043] In some embodiments, the substrate may be one of a DBC substrate, an AMB substrate, and a ZTA substrate. Preferably, in this embodiment, the substrate is a DBC substrate.

[0044] In some embodiments, the bonding wire may be an aluminum wire, a copper wire, other metal wires, an aluminum ribbon, or other metal ribbons. Preferably, the bonding wire is an aluminum wire.

[0045] Preferably, the purity of the aluminum wire is greater than 99.99%. The wire diameter of the aluminum wire is 8-20 mil. The wire diameter and number of wires can be selected according to the current level required by the module.

[0046] In some embodiments, before step S2, the chip is also soldered to the substrate and bonded to the copper clad on the surface of the substrate under the adsorption and fixation of the tooling.

[0047] In some embodiments, step S3 specifically includes: fixing the substrate welding fixture at a selected position on the heat dissipation base plate, placing the welding sheet on the heat dissipation base plate and in the welding fixture, using a vacuum suction nozzle to suck the bonded substrate and transfer it to the welding fixture, welding the substrate to the heat dissipation base plate, and then assembling the frame, bonding the frame, and pouring glue to complete the packaging.

[0048] In some embodiments, the bonding between the substrates and the bonding between the substrate and the heat dissipation base plate are completed using a bonding machine; the bonding method is one of cold pressure ultrasonic welding, ultrasonic linear welding, ultrasonic torque welding, and hot pressure ultrasonic welding.

[0049] In some embodiments, the welding fixture is made of graphite or metal. Example 1

[0050] like Figure 1 , Figure 2 As shown, the tooling for interconnecting substrates in this embodiment includes:

[0051] A vacuum adsorption platform 1 is provided with a plurality of acupuncture points 2, the acupuncture points 2 are suitable for placing a substrate and limiting the substrate; the arrangement mode and arrangement interval of the acupuncture points 2 are consistent with the arrangement mode and arrangement interval of the interconnected substrate to be formed; each acupuncture point 2 is provided with a plurality of vacuum holes 3;

[0052] The vacuum pipeline is connected with the vacuum hole, and the vacuum pipeline is used to evacuate the vacuum hole to adsorb and fix the substrate in the acupuncture point.

[0053] Specifically, in this embodiment, the tooling is used to interconnect the half-bridge modules, and the half-bridge modules are divided into an upper bridge DBC and a lower bridge DBC.

[0054] In this embodiment, 6 groups of 12 acupoints 2 are arranged on the vacuum adsorption platform 1, each group of acupoints includes 2 acupoints, two of which correspond to each other, and the distance d between the two acupoints in each group of acupoints is 2-5 cm. 25 vacuum holes are opened on the acupoint surface. The vacuum holes are arranged in 5 rows and 5 columns with equal spacing. Example 2

[0055] The precise positioning substrate welding method of this embodiment is used to weld a half-bridge module, and includes the following steps:

[0056] 1. Use a vacuum nozzle to place the DBC substrate upper bridge 8 and the DBC substrate lower bridge 9 in two corresponding acupoints of a group of acupoints of the tooling of Example 1, and fix the DBC substrate upper bridge and the DBC substrate lower bridge by adsorption through the tooling, wherein the distance d between the two acupoints in each group of acupoints is designed to be 2.2 mm;

[0057] 2. Under the adsorption and fixation of the tooling, mount the chip 4 on the DBC substrate, then weld the chip and the DBC substrate, and then use the bonding machine to bond the chip to the copper clad on the surface of the DBC substrate using aluminum wire as the bonding wire. The purity of the aluminum wire is greater than 99.99%, and the wire diameter of the aluminum wire is 8 mil; Figure 3 As shown;

[0058] 3. Under the adsorption and fixation of the tooling, the upper bridge of the DBC substrate and the lower bridge of the DBC substrate adsorbed and fixed in the acupoint are bonded and interconnected by a bonding machine using aluminum wire as a bonding wire to obtain DBC3; Figure 4 As shown;

[0059] 4. Use a vacuum suction nozzle to suck the bonded DBC3 into the tray and transport it to the system welding station; the heat sink 5 is placed on the reflow tray by a manipulator or a suction nozzle, the substrate welding fixture 7 is fixed to the selected position on the heat sink, the soldering sheet 6 is placed on the heat sink and in the welding fixture, and the bonded DBC3 is sucked and transferred to the welding fixture by a vacuum suction nozzle to weld the DBC3 to the heat sink, and then the frame is assembled, the frame is bonded, and the glue is poured to complete the packaging, such as Figure 5 , Figure 6 As shown; wherein, the welding fixture is made of graphite, the welding fixture can be fixed to the heat dissipation base plate, and the welding fixture is provided with a limiting groove suitable for placing a group of DBC substrates and limiting them.

[0060] Comparative Example 1

[0061] This comparative example is an existing substrate welding method, which includes the following steps: first mounting the chip on the DBC, then welding the chip to the DBC, and then bonding the chip to the copper clad on the surface of the DBC; using a clamp recorded in the Chinese patent document with publication number CN 218452728 U to fix the positions of two DBCs on the heat dissipation base plate, the width of the partition in the clamp is 2.2 mm, mounting the DBC with the chip welded on the heat dissipation base plate, and then performing welding, frame assembly, frame bonding, and glue pouring on the entire system to complete the packaging.

[0062] 13 samples were welded respectively using the welding methods of the above-mentioned embodiment 2 and comparative example 1, and the spacing between adjacent DBCs after welding was measured. It can be seen from the data in Table 1 that the substrate welding method of the embodiment of the present invention can more accurately control the spacing between two adjacent DBC substrates on the heat dissipation base plate.

[0063] Table 1

[0064]

[0065] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A precise positioning substrate welding method, characterized in that: The following steps are involved: S1. Placing the substrate in the corresponding acupuncture points in the tooling for interconnecting substrates, and fixing the substrate by adsorption through the tooling, wherein the tooling for interconnecting substrates comprises: a vacuum adsorption platform, wherein the vacuum adsorption platform is provided with a plurality of acupuncture points, wherein the acupuncture points are suitable for placing the substrate and limiting the substrate; the arrangement mode and arrangement interval of the acupuncture points are consistent with the arrangement mode and arrangement interval of the interconnected substrate to be formed; each of the acupuncture points is provided with a plurality of vacuum holes; a vacuum pipeline, wherein the vacuum pipeline is connected with the vacuum holes, and the vacuum pipeline is used to vacuum the vacuum holes to adsorb and fix the substrate in the acupuncture points; each of the acupuncture points is provided with 12 to 48 vacuum holes; the vacuum holes are arranged at equal intervals; at least 6 groups of acupuncture points are provided on the vacuum adsorption platform, wherein each group comprises 2 acupuncture points, and the interval between the 2 acupuncture points in each group is 2 to 5 cm; S2. Under the adsorption and fixation of the tooling, bonding is performed between adjacent substrates to complete the interconnection between the substrates; S3. Fix the substrate welding fixture at a selected position on the heat dissipation base plate, and place the bonded substrate into the welding fixture to perform welding between the substrate and the heat dissipation base plate.

2. The precise positioning substrate welding method according to claim 1, characterized in that: The substrate is one of a DBC substrate, an AMB substrate and a ZTA substrate.

3. The precise positioning substrate welding method according to claim 1, characterized in that: Aluminum wire or copper wire is used to bond adjacent substrates; the purity of the bonding wire is greater than 99.99%; the wire diameter of the bonding wire is 8~20mil.

4. The precise positioning substrate welding method according to claim 1, characterized in that: Before step S2, the method also includes welding the chip to the substrate and bonding it to the copper cladding on the surface of the substrate under the adsorption and fixation of the tooling.

5. The precise positioning substrate welding method according to claim 1, characterized in that: Step S3 specifically includes: fixing the substrate welding fixture at a selected position on the heat dissipation base plate, placing the welding sheet on the heat dissipation base plate and in the welding fixture, using a vacuum suction nozzle to suck the bonded substrate and transfer it to the welding fixture, welding the substrate to the heat dissipation base plate, and then assembling the frame, bonding the frame, and pouring glue to complete the packaging.

6. The precise positioning substrate welding method according to claim 3, characterized in that: The bonding between the substrates and the bonding between the substrate and the heat dissipation base plate are completed by a bonding machine; the bonding method is one of cold pressure ultrasonic welding, ultrasonic linear welding, ultrasonic torque welding, and hot pressure ultrasonic welding.

7. The precise positioning substrate welding method according to claim 1, characterized in that: The welding fixture is made of graphite or metal.

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