A method for fixing chips in a vacuum sintering furnace

Abstract

This application relates to the technical field of chip sintering, and particularly to a method for fixing a chip in a vacuum sintering furnace, including the following steps: S1: Open a rectangular groove on the gold plating layer according to the chip size; S2: Place the solder sheet on the gold plating layer, and the solder sheet is located within the area enclosed by the rectangular groove; S3: Place the chip on the solder sheet to form a material to be sintered; S4: Transfer the material to be sintered into a sintering device for sintering and fixing; This application has the effect that by opening a rectangular groove on the gold plating layer, the flow range of the molten solder sheet can be restricted, thereby realizing the fixation of the chip position during sintering. Moreover, since no counterweight is provided, the solder sheet will not overflow after sintering, the appearance is good, and the surface of the chip is clean, without defects such as scratches and breakage that may be caused when taking and placing the counterweight, which is beneficial to improving the efficiency of subsequent shell bonding.

Description

Technical Field

[0001] This application relates to the technical field of chip sintering, and particularly to a method for fixing a chip in a vacuum sintering furnace. Background Art

[0002] Sintering is a process that converts the dense mechanical connection between powder particles into a solid metallurgical bond between particles when heated. Sintering is a widely used chip-to-substrate connection technology that enhances the service life of power modules and strengthens power density. The chip-substrate connection formed by sintering is based on the enhanced surface metal interdiffusion of micron- or nano-sized particles.

[0003] After the chip sintering is completed, the PADs of the package and the chip need to be aligned and then bonded. Currently, the bonding tools generally include two types: manual bonding machines and automatic bonding machines. Among them, manual bonding has low requirements for the accuracy of the chip sintering position because the PADs of the package and the chip can be manually aligned, but the bonding efficiency is too low; automatic bonding has high efficiency, but has high requirements for the position of the chip sintering. If you want to improve the bonding efficiency, you must fix the chip position. Since the surface tension and fluidity of the molten solder will cause the chip to shift, in the prior art, when sintering and fixing the chip, the chip position is fixed by placing a weight on the chip during sintering.

[0004] Regarding the above related technologies, the applicant believes that when fixing the chip position by placing a weight on the chip, during the sintering process in the reflow furnace, the solder that gradually melts into a liquid state will overflow from the periphery of the chip under the influence of the pressure of the weight. Summary of the Invention

[0005] In order to reduce the possibility of solder overflowing from the periphery of the chip during the chip sintering and fixing process, this application provides a method for fixing a chip in a vacuum sintering furnace.

[0006] A method for fixing a chip in a vacuum sintering furnace provided by this application adopts the following technical solutions:

[0007] A method for fixing a chip in a vacuum sintering furnace includes the following steps:

[0008] S1: Open a rectangular groove on the gold plating layer according to the chip size;

[0009] S2: Place the solder sheet on the gold plating layer, and the solder sheet is located within the area surrounded by the rectangular groove;

[0010] S3: Place the chip on the solder sheet to form a material to be sintered;

[0011] S4: Transfer the material to be sintered to a sintering device for sintering and fixing.

[0012] By adopting the above technical solution, first, a rectangular groove with a suitable size is opened at an appropriate position on the gold plating layer according to the size of the chip to be sintered. Then, the solder sheet is placed on the gold plating layer, and the solder sheet should be located within the area surrounded by the rectangular groove. Immediately afterwards, the staff places the chip to be sintered on the solder sheet to form the material to be sintered. Finally, the material to be sintered is transferred into the sintering equipment for sintering and fixing. When heating in the sintering equipment, the solder sheet absorbs heat and becomes molten solder. However, the molten solder is restricted by the rectangular groove and always remains within the rectangular groove, thereby realizing the fixation of the chip position during sintering. The designed vacuum sintering furnace fixes the direction of the chip. By opening a rectangular groove on the gold plating layer, the flow range of the molten solder sheet can be restricted, thereby realizing the fixation of the chip position during sintering. Moreover, since no counterweight is set, the solder sheet will not overflow after sintering, and the appearance is good. Also, the surface of the chip is clean, without any defects such as scratches and breakages that may be caused when taking and placing the counterweight, which is beneficial to improving the efficiency of subsequent package bonding.

[0013] In a specific feasible implementation, the S2 step includes the following steps:

[0014] S21: After ultrasonic cleaning the gold plating layer with alcohol, dry it.

[0015] S22: Place the solder sheet within the area surrounded by the rectangular groove on the gold plating layer.

[0016] By adopting the above technical solution, the designed S2 step can clean the gold powder generated during the opening of the rectangular groove, reducing the impact on the subsequent chip sintering.

[0017] In a specific feasible implementation, in the S21 step, first make the opening of the rectangular groove face downwards, and then ultrasonic clean the gold plating layer with alcohol and dry it.

[0018] By adopting the above technical solution, the designed S21 step can improve the cleaning strength and efficiency of impurities such as gold powder by placing it upside down.

[0019] In a specific feasible implementation, the drying parameters in the S21 step are set to dry for ten minutes at 80 °C.

[0020] By adopting the above technical solution, the designed drying parameters can achieve an optimal value between the chip yield and the drying speed.

[0021] In a specific feasible implementation, in the S1 step, a rectangular groove is opened on the gold plating layer by using ultraviolet laser marking.

[0022] By adopting the above technical solution, the designed S1 step can achieve precise control of the size of the rectangular groove by using ultraviolet laser marking, and minimize the damage to the nickel plating layer under the gold plating layer to the greatest extent.

[0023] In a specific feasible implementation, the inner border of the rectangular groove is 0.2 mm larger than the chip size, and the width of the rectangular groove is 0.5 mm.

[0024] By adopting the above technical solution, the designed size relationship between the rectangular groove and the chip can limit the flow position of the solder sheet after melting on the premise of saving laser marking energy.

[0025] In a specific feasible implementation, in the S4 step, a fixing tooling is used to fix the material to be sintered. The fixing tooling includes a placement plate, U-shaped rods, clamping strips, and springs;

[0026] The number of the U-shaped rods is two, and the two U-shaped rods are respectively connected to the opposite ends on the same side of the placement plate;

[0027] The number of the clamping strips is two, and the two clamping strips are respectively arranged at the two long sides of the U-shaped rods, and the clamping strips are slidably connected to the horizontal sections of the U-shaped rods;

[0028] The number of the springs is two, and the two springs are respectively connected to the two clamping strips, and the springs are connected to the placement plate for making the two clamping strips move towards each other.

[0029] By adopting the above technical solution, a plurality of prepared materials to be sintered are placed on the placement plate, and then the springs apply force to the clamping strips, and the two clamping strips cooperate to fix the materials to be sintered on the placement plate; the designed fixing tooling is convenient for placing the materials to be sintered through the placement plate, is convenient for the clamping strips to slide while reducing the thermal deformation of the placement plate through the U-shaped rods, and is convenient for fixing the materials to be sintered on the placement plate through the cooperation of the clamping strips and the springs.

[0030] In a specific feasible implementation, it further includes an alignment tooling. The alignment tooling includes a rotating rod, alignment pieces, and two sliding blocks;

[0031] The two sliding blocks are respectively slidably connected to the two clamping strips;

[0032] The rotating rod passes through and is slidably connected to the sliding blocks, and there is a rotating gap between the rotating rod and the sliding blocks;

[0033] The alignment pieces are connected to the rotating rod, and one end of the alignment piece far from the rotating rod can abut against the outer side wall of the kovar ring.

[0034] By adopting the above technical solution, a force is applied to the rotating rod, and the rotating rod moves along the long side direction of the clamping strip through the sliding block. Then, the alignment piece is rotated so that the alignment piece abuts against the outer side wall of the kovar ring. A force is applied to the kovar ring to keep the positions of multiple kovar rings flush, which is convenient for subsequent automatic bonding of the package. The designed alignment tooling facilitates the movement of the rotating rod through the sliding block, facilitates the installation of the alignment piece through the rotating rod, and facilitates the alignment of multiple kovar rings through the alignment piece, thereby facilitating the subsequent automatic bonding operation of the package.

[0035] In summary, the present application includes at least one of the following beneficial technical effects:

[0036] 1. The designed method for fixing the chip in the vacuum sintering furnace can limit the flow range of the solder sheet after melting by opening rectangular grooves in the gold plating layer, thereby realizing the fixation of the chip position during sintering. Moreover, since no counterweight is provided, the solder sheet will not overflow after sintering, and the appearance is good. Also, the surface of the chip is clean, without defects such as scratches and breakages that may be caused when taking and placing the counterweight, which is beneficial to improving the efficiency of subsequent package bonding.

[0037] 2. The designed method for fixing the chip in the vacuum sintering furnace facilitates the placement of the material to be sintered through the placement plate. The U-shaped rod can facilitate the sliding of the clamping strip while reducing the thermal deformation of the placement plate. The cooperation of the clamping strip and the spring facilitates the fixation of the material to be sintered on the placement plate.

[0038] 3. The designed method for fixing the chip in the vacuum sintering furnace facilitates the movement of the rotating rod through the sliding block, facilitates the installation of the alignment piece through the rotating rod, and facilitates the alignment of multiple kovar rings through the alignment piece, thereby facilitating the subsequent automatic bonding operation of the package. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 is a schematic structural view of the material to be sintered in the method for fixing the chip in the vacuum sintering furnace according to the embodiment of the present application.

[0040] Figure 2 is along Figure 1 sectional view.

[0041] Figure 3 is a schematic structural view of the fixing tooling and the alignment tooling in the method for fixing the chip in the vacuum sintering furnace according to the embodiment of the present application.

[0042] Description of the reference numerals: 1, kovar ring; 2, nickel plating layer; 3, gold plating layer; 31, rectangular groove; 4, solder sheet; 5, chip; 6, fixing tooling; 61, placement plate; 62, U-shaped rod; 63, clamping strip; 64, spring; 7, alignment tooling; 71, rotating rod; 72, alignment piece; 73, sliding block. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0043] The following will further elaborate on this application with reference to the accompanying drawings. Figures 1-3 This application will be further described in detail below.

[0044] An embodiment of this application discloses a method for fixing a chip in a vacuum sintering furnace.

[0045] Referring to Figure 1 and Figure 2 , in a method for fixing a chip in a vacuum sintering furnace, a fixing tooling 6 and an alignment tooling 7 are used during the operation. The material to be sintered includes a kovar ring 1, a nickel plating layer 2, a gold plating layer 3, a solder sheet 4, and a chip 5. The nickel plating layer 2 is installed in the accommodation cavity of the kovar ring 1. The gold plating layer 3 is laid above the nickel plating layer 2. A rectangular groove 31 is formed in the gold plating layer 3. The solder sheet 4 is placed on the gold plating layer 3 and is located within the rectangular groove 31. The chip 5 is placed on the solder sheet 4.

[0046] Referring to Figure 2 and Figure 3 , the fixing tooling 6 includes a placement plate 61, U-shaped rods 62, clamping strips 63, and springs 64. The number of U-shaped rods 62 is two. The two U-shaped rods 62 are parallel and are respectively welded to the opposite ends on the same side of the placement plate 61. The number of clamping strips 63 is two. The two clamping strips 63 are respectively arranged at the long side ends of the U-shaped rods 62, and the clamping strips 63 are slidably connected to the horizontal sections of the U-shaped rods 62. The number of springs 64 is also two. The two springs 64 are respectively welded to the two clamping strips 63, and the ends of the springs 64 away from the clamping strips 63 are welded to the placement plate 61 for making the two clamping strips 63 move towards each other.

[0047] Referring to Figure 2 and Figure 3 , the alignment tooling 7 includes a rotating rod 71, alignment pieces 72, and two sliding blocks 73. The two sliding blocks 73 are respectively slidably connected to the two clamping strips 63. The sliding blocks 73 can slide along the long sides of the clamping strips 63. The axial direction of the rotating rod 71 is consistent with the long side of the clamping strip 63. The rotating rod 71 passes through the two sliding blocks 73 at the same time. The rotating rod 71 is slidably connected to the sliding blocks 73, and there is a rotating gap between the rotating rod 71 and the sliding blocks 73. The alignment pieces 72 are welded to the rotating rod 71, and the ends of the alignment pieces 72 away from the rotating rod 71 can abut against the outer side wall of the kovar ring 1.

[0048] Referring to Figure 1 , Figure 2 and Figure 3 , a method for fixing a chip in a vacuum sintering furnace includes the following steps:

[0049] S1: A rectangular groove 31 is formed in the gold plating layer 3 by means of ultraviolet laser marking according to the size of the chip 5. The inner border of the rectangular groove 31 is 0.2 mm larger than the size of the chip 5, and the groove width of the rectangular groove 31 is 0.5 mm.

[0050] S2: Place the solder sheet 4 onto the gold plating layer 3, and the solder sheet 4 is located within the area enclosed by the rectangular groove 31;

[0051] S21: First, make the opening of the rectangular groove 31 face downward, then ultrasonically clean the gold plating layer 3 with alcohol and dry it. The drying parameters are drying for 10 minutes at 80°C;

[0052] S22: First, make the opening of the rectangular groove 31 face upward, then place the solder sheet 4 onto the gold plating layer 3 within the area enclosed by the rectangular groove 31;

[0053] S3: Place the chip 5 on the solder sheet 4 to form a material to be sintered;

[0054] S4: Place multiple materials to be sintered on the placement plate 61. Under the action of the spring 64, the two clamping strips 63 make the multiple materials to be sintered close together. Then apply force to the rotating rod 71. The rotating rod 71 drives the alignment piece 72 to abut against the outer side wall of the kovar ring 1. Apply force to the kovar ring 1 to align multiple kovar rings 1, and then transfer them into the sintering equipment for sintering and fixing.

[0055] The implementation principle of the method for fixing chips in a vacuum sintering furnace according to the embodiments of the present application is as follows: Use ultraviolet laser marking to open the rectangular groove 31 on the gold plating layer 3 according to the size of the chip 5, so that the inner border of the rectangular groove 31 is 0.2 mm larger than the size of the chip 5, and the groove width of the rectangular groove 31 is 0.5 mm; then place the solder sheet 4 onto the gold plating layer 3 and make the solder sheet 4 located within the area enclosed by the rectangular groove 31; then make the opening of the rectangular groove 31 face downward, and then ultrasonically clean the gold plating layer 3 with alcohol and dry it. The drying parameters are drying for 10 minutes at 80°C; after drying, first make the opening of the rectangular groove 31 face upward, then place the solder sheet 4 onto the gold plating layer 3 within the area enclosed by the rectangular groove 31; place the chip 5 on the solder sheet 4 to form a material to be sintered; place multiple materials to be sintered on the placement plate 61. Under the action of the spring 64, the two clamping strips 63 make the multiple materials to be sintered close together. Then apply force to the rotating rod 71. The rotating rod 71 drives the alignment piece 72 to abut against the outer side wall of the kovar ring 1. Apply force to the kovar ring 1 to align multiple kovar rings 1, and then transfer them into the sintering equipment for sintering and fixing.

[0056] The above are all the preferred embodiments of the present application. The protection scope of the present application is not limited by this. Therefore, all equivalent changes made according to the structure, shape, and principle of the present application should be covered within the protection scope of the present application.

Claims

1. A method for fixing a chip in a vacuum sintering furnace, characterized in that: It includes the following steps: S1: Open a rectangular groove (31) on the gold plating layer (3) according to the size of the chip (5); S2: Place the solder sheet (4) on the gold plating layer (3), and the solder sheet (4) is located within the area surrounded by the rectangular groove (31); S3: Place the chip (5) on the solder sheet (4) to form a material to be sintered; S4: Transfer the material to be sintered to a sintering device for sintering and fixing; In the step S4, a fixing tooling (6) is used to fix the material to be sintered. The fixing tooling (6) includes a placement plate (61), a U-shaped rod (62), a clamping strip (63), and a spring (64); The number of the U-shaped rods (62) is two, and the two U-shaped rods (62) are respectively connected to the opposite ends of the same side of the placement plate (61); The number of the clamping strips (63) is two, and the two clamping strips (63) are respectively arranged at the two long ends of the U-shaped rod (62), and the clamping strip (63) is slidably connected to the horizontal section of the U-shaped rod (62); The number of the springs (64) is two, and the two springs (64) are respectively connected to the two clamping strips (63), and the spring (64) is connected to the placement plate (61) for making the two clamping strips (63) move towards each other; It further includes an alignment tooling (7). The alignment tooling (7) includes a rotating rod (71), an alignment piece (72), and two sliding blocks (73); The two sliding blocks (73) are respectively slidably connected to the two clamping strips (63); The rotating rod (71) passes through and is slidably connected to the sliding block (73), and there is a rotating gap between the rotating rod (71) and the sliding block (73); The alignment piece (72) is connected to the rotating rod (71), and one end of the alignment piece (72) away from the rotating rod (71) can abut against the outer side wall of the kovar ring (1).

2. The method for fixing a chip in a vacuum sintering furnace according to claim 1, wherein: The step S2 includes the following steps: S21: Use alcohol ultrasonic cleaning on the gold plating layer (3) and then dry it; S22: Place the solder sheet (4) on the gold plating layer (3) within the area surrounded by the rectangular groove (31).

3. The method for fixing a chip in a vacuum sintering furnace according to claim 2, wherein: In the step S21, first make the opening of the rectangular groove (31) face downwards, and then use alcohol ultrasonic cleaning on the gold plating layer (3) and then dry it.

4. The method for fixing a chip in a vacuum sintering furnace according to claim 2, wherein: The drying parameters in the step S21 are set to dry for ten minutes at 80 °C.

5. The method for fixing a chip in a vacuum sintering furnace according to any one of claims 1-4, characterized in that: In the step S1, a rectangular groove (31) is opened on the gold plating layer (3) by means of ultraviolet laser marking.

6. The method for fixing a chip in a vacuum sintering furnace according to claim 5, characterized in that: The inner border of the rectangular groove (31) is 0.2 mm larger than the size of the chip (5), and the groove width of the rectangular groove (31) is 0.5 mm.

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