Chip sintering method

Abstract

The present invention discloses a chip sintering method, in which a sintering furnace is used to sinter the chip. The method includes the following steps: placing a workpiece on a fixture and fixing the fixture to the top surface of a lower workbench; introducing a protective gas into the furnace body and adjusting the vacuum level within the furnace body; causing a magnetic field generating device within the lower workbench to generate a magnetic field, and an upper workbench made of a magnetic material to move toward the lower workbench under the action of the magnetic field, thereby pressurizing the workpiece on the lower workbench; an electromagnetic heating coil wrapped around the furnace body heats the furnace body, causing the interior of the furnace body to heat up and sinter the workpiece; after sintering is completed, the furnace body is depressurized and the workpiece is removed, thereby obtaining the sintered chip. Due to the rapid heating speed of electromagnetic heating and the more precise control of the downward pressing speed of electromagnetic drive, the chip sintering process is fast and more precise, effectively reducing damage to the sample during the pressurization process, while also achieving control of the pressure holding time and programmed pressurization and decompression.

Description

Technical Field

[0001] The present invention relates to the technical field of chip packaging, and in particular to a chip sintering method. Background Art

[0002] In the field of chip packaging interconnects, a layer of nano-copper paste is typically applied between the substrate and the chip using techniques such as screen printing. The paste is then sintered at high temperature and pressure to improve the density and physical properties of the connection layer between the substrate and the chip. At high temperatures, the copper paste's grains grow in absorptive capacity, while voids (pores) and grain boundaries gradually decrease. Through the transfer of matter, the total volume shrinks and the density increases, ultimately forming a dense polycrystalline sintered body with a microstructure, forming a network of interconnected silver particles.

[0003] Existing sintering furnaces usually use hydraulic pressure or mechanical pressure to generate heat using resistance. For example, the Chinese invention patent application with publication number CN114608311A, entitled “Sintering equipment and atmosphere-controlled pressure sintering mechanism thereof”, uses two upper and lower pressure components to block the telescopic tube, so that a closed sintering chamber is formed inside the telescopic tube. Both pressure components are provided with electric heating coils or electric heating plates to heat the components in the heating chamber. A screw-nut mechanism, a gear rack mechanism, and a cylinder are used to drive the upper pressure head downward until the upper pressure head contacts and pressurizes the product. This method of heating the heating chamber with an electric heating coil or an electric heating plate has the disadvantage of a slow heating speed of the heating chamber. Moreover, the mechanical pressure method has a low control accuracy of the downward pressure, resulting in slow chip processing speed and processing accuracy, easy damage to the sample, and inability to achieve accurate pressure increase / decompression operation and accurate control of the holding time. Summary of the Invention

[0004] The object of the present invention is to provide a chip sintering method with the characteristics of fast processing speed and more precise pressurization.

[0005] To achieve this object, the present invention adopts the following technical solutions:

[0006] A chip sintering method is provided, wherein the chip is sintered in a sintering furnace, wherein the sintering furnace comprises a furnace body, an upper workbench and a lower workbench, wherein the lower workbench is located directly below the upper workbench, and the upper workbench is vertically movable. The method comprises the following steps:

[0007] (1) placing the workpiece on a fixture, and fixing the fixture to the top surface of the lower workbench;

[0008] (2) introducing protective gas into the furnace body and adjusting the vacuum degree in the furnace body;

[0009] (3) causing the magnetic field generating device in the lower workbench to generate a magnetic field, so that the upper workbench made of magnetic material moves toward the lower workbench under the action of the magnetic field and pressurizes the workpiece on the lower workbench;

[0010] (4) heating the furnace body with an electromagnetic heating coil wound around the furnace body, thereby increasing the temperature inside the furnace body and sintering the workpiece;

[0011] (5) After sintering is completed, the furnace body is depressurized and the workpiece is taken out to obtain the sintered chip.

[0012] Furthermore, a tension sensor is connected between the upper workbench and the inner wall of the furnace body, and the pressure of the upper workbench on the workpiece is obtained through the tension sensor;

[0013] The magnetic field generating device is connected to an electromagnetic control device, and the magnetic field control device controls the intensity and shape of the magnetic field generated by the magnetic field generating device according to the tension signal of the tension sensor.

[0014] Furthermore, the electromagnetic control device is connected to the electromagnetic heating coil, and the electromagnetic control device controls the heating temperature of the electromagnetic heating coil.

[0015] Furthermore, a vertical guide rail is installed on the top wall of the furnace body, the vertical guide rail is in a hollow cylindrical shape, and a plurality of guide grooves are provided on the inner wall of the vertical guide rail;

[0016] A sliding column is provided on the top of the upper workbench, and a protrusion matching the guide groove is provided on the outer wall of the sliding column. The sliding column is inserted into the guide groove and slidably matched with the guide groove.

[0017] Furthermore, a buffer is provided on the inner wall of the furnace body, one end of the tension sensor is connected to the buffer, and the other end of the tension sensor is connected to the top of the sliding column;

[0018] The tension sensor and the buffer are located in the vertical guide rail.

[0019] Furthermore, the furnace body is connected to a gas pipeline, and the gas pipeline is connected to a vacuum pump, a gas cylinder and an overflow valve;

[0020] In the step (2), firstly, a vacuum pump is used to make the furnace body reach a preset vacuum degree, then the threshold value of the overflow valve is adjusted, and the gas cylinder is used to fill the furnace body with protective gas and the furnace body is filled with protective gas for 2-4 times.

[0021] Furthermore, in step (4), when the workpiece is a copper sheet welding structure, the heating rate in the furnace body is less than or equal to 0.4°C / s;

[0022] The sintering temperature gradient is as follows:

[0023] The temperature inside the furnace rises to 30-100°C and is kept warm for 2-8 minutes;

[0024] The temperature in the furnace rises to 110-120°C and is kept warm for 7-13 minutes;

[0025] The temperature inside the furnace rises to 120-600° C. and is kept warm for 25-35 minutes.

[0026] Furthermore, in step (4), when the workpiece is a flexible copper-clad laminate with micropores, solder is filled in the micropores of the flexible copper-clad laminate with micropores, the heating rate in the furnace body is less than or equal to 0.1°C / s, and the maximum temperature in the furnace body does not exceed 250°C.

[0027] Furthermore, the furnace body includes an outer wall and an inner wall, the space between the outer wall and the inner wall is filled with a heat insulating material, and the material of the inner wall is a magnetic material;

[0028] The electromagnetic heating coil is wound around the outer side of the inner wall of the furnace.

[0029] Furthermore, a mounting hole is provided on the top surface of the lower workbench;

[0030] The clamp is provided with a through hole corresponding to the mounting hole, and the positioning rod passes through the mounting hole and the through hole so that the clamp is fixed to the lower workbench.

[0031] The technical solution provided by the present invention can have the following beneficial effects:

[0032] In the sintering method of the present invention, the workpiece in the sintering furnace is sintered by electromagnetic heating, and the upper workbench is pressurized on the workpiece by electromagnetic driving. Based on the characteristics of fast heating speed of electromagnetic heating and more precise control of downward pressing speed of electromagnetic driving, the chip sintering processing speed is fast and the processing is more precise, which effectively reduces the damage to the sample during the pressurization process, and at the same time realizes the control of holding time and realizes programmed pressurization and decompression. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 1 is a schematic structural diagram of a sintering furnace according to an embodiment of the present invention;

[0034] Figure 2 yes Figure 1 A schematic structural diagram of the furnace body of the sintering furnace;

[0035] Among them, the furnace body 1, the furnace outer wall 12, the furnace inner wall 13, the electromagnetic heating coil 11, the vertical guide rail 14, the tension sensor 15, the upper workbench 2, the sliding column 21, the lower workbench 3, the magnetic field generating device 31, the electromagnetic control device 4, the temperature sensor 5, the air pressure indicator 61, the gas cylinder 62, the vacuum pump 63, and the overflow valve 64. DETAILED DESCRIPTION

[0036] like Figure 1 and Figure 2 As shown, the present invention provides a chip sintering method, which uses a sintering furnace to sinter the chip. The sintering furnace includes a furnace body 1, an upper workbench 2 and a lower workbench 3. The lower workbench 3 is located directly below the upper workbench 2. The upper workbench 2 can move vertically. The method includes the following steps:

[0037] (1) Place the workpiece on the fixture and fix the fixture to the top surface of the lower workbench 3;

[0038] (2) introducing protective gas into the furnace body 1 and adjusting the vacuum degree in the furnace body 1;

[0039] (3) The magnetic field generating device 31 in the lower workbench 3 generates a magnetic field, and the upper workbench 2 made of magnetic material moves toward the lower workbench 3 under the action of the magnetic field, and pressurizes the workpiece on the lower workbench 3;

[0040] (4) The electromagnetic heating coil 11 wound around the furnace body 1 heats the furnace body 1, thereby increasing the temperature inside the furnace body 1 and sintering the workpiece;

[0041] (5) After sintering is completed, the pressure in the furnace body 1 is released and the workpiece is taken out to obtain the sintered chip.

[0042] In the sintering method of the present invention, the workpiece in the sintering furnace is sintered by electromagnetic heating, and the upper workbench 2 is pressurized on the workpiece by electromagnetic driving. Based on the characteristics of fast heating speed of electromagnetic heating and more precise control of downward pressing speed of electromagnetic driving, the chip sintering processing speed is fast and the processing is more precise.

[0043] Specifically, the electromagnetic heating coil 11 uses the principle of electromagnetic induction to convert electrical energy into thermal energy, so that the inner wall 13 of the furnace itself generates heat at a high speed, thereby achieving the purpose of rapid heating. The upper workbench 2 is constructed of magnetic material, and when it is inside the magnetic field generated by the magnetic field generating device 31, it can generate an induced magnetic field inside the upper workbench 2. The magnetic field generating device 31 can magnetize the upper workbench 2 and generate a magnetic field with opposite magnetic poles to the magnetic field generating device 31. Based on the different magnetic poles between the magnetic field generating device 31 and the upper workbench 2, the upper workbench 2 will be affected by the magnetic field and move downward, thereby pressurizing the workpiece placed on the lower workbench 3. Because of its high magnetic control accuracy, it can control the pressurization speed, effectively reduce the damage to the sample during the pressurization process, and improve processing accuracy.

[0044] It should be noted that, in the present invention, the furnace body 1 can be designed to be larger in size to have a large capacity by using electromagnetic heating and pressurization, which can realize the processing of chips of various sizes and batch processing of chips, thereby greatly improving the processing efficiency of chips.

[0045] Specifically, the furnace body 1 includes an outer wall 12 and an inner wall 13. The space between the outer wall 12 and the inner wall 13 is filled with thermal insulation material, and the material of the inner wall 13 is a magnetic material. The electromagnetic heating coil is wrapped around the outside of the inner wall 13. The outer wall 12 and the inner wall 13 are both cylindrical. The outer wall 12 is made of iron products to isolate the magnetic interference from the inside of the furnace to the outside of the furnace. The thermal insulation material can be aerogel insulation material, carbon insulation material, or composite insulation material, such as silica aerogel or carbon silicon plate. The inner wall 13 is made of magnetic material, and its material is such as Fe, Co, Ni elements and their alloys, rare earth elements and their alloys, or a compound containing Mn.

[0046] To facilitate the placement of workpieces into furnace body 1, the furnace body 1 is divided into a fixed portion and a movable portion. The movable portion serves as a door, pivotally connected to the fixed portion. The door is magnetically controlled to open and close. When the sintering furnace is operating, the door is closed; when the furnace is finished and the temperature needs to be lowered, the door is opened.

[0047] During the sintering process of the chip, the pressure applied to the workpiece needs to be monitored in order to perform precision processing and improve product quality. A tension sensor 15 is connected between the upper workbench 2 and the inner wall of the furnace body 1, and the pressure applied by the upper workbench 2 to the workpiece is obtained through the tension sensor 15; the magnetic field generating device 31 is connected to the electromagnetic control device 4, and the magnetic field control device controls the intensity and shape of the magnetic field generated by the magnetic field generating device 31 according to the tension signal of the tension sensor 15.

[0048] The tension sensor 15 can operate at high temperatures (600°C) with minimal linearity, hysteresis, and creep errors. The tension sensor 15 converts the tension signal exerted on the upper worktable 2 into a measurable electrical signal for feedback. Upon receiving the feedback signal from the tension sensor 15, the electromagnetic control device 4 adjusts the frequency and intensity of the current, thereby controlling the intensity and shape of the magnetic field generated by the magnetic field generating device 31. Ultimately, this controls the attractive force exerted on the upper worktable 2, thereby precisely controlling the pressure exerted on the workpiece by the upper worktable 2.

[0049] Based on the requirements of chip sintering processing, it is necessary to control the heating rate in the furnace body 1, and adjust the temperature in the furnace at different stages of the chip sintering process, so that the electromagnetic control device 4 is connected to the electromagnetic heating coil 11, and the electromagnetic control device 4 controls the heating temperature of the electromagnetic heating coil 11.

[0050] The electromagnetic control device 4 is used to generate low-frequency, medium-frequency, ultrasonic, or high-frequency current and has temperature and pressure setting functions. The digital signal representing the furnace temperature is fed back by the temperature sensor, which positively and negatively regulates the heat energy generated by the furnace inner wall 13 to achieve thermal dynamic equilibrium. By controlling the current frequency, the electromagnetic control device 4 can control the intensity of the alternating magnetic field generated by the coil, thereby achieving the purpose of controlling the heating rate. Preferably, the temperature sensor 5 within the furnace body 1 is an infrared temperature sensor 5, which can sensitively sense changes in the furnace temperature and feedback the temperature changes to the electromagnetic control device 4.

[0051] Specifically, the electromagnetic control device 4 rectifies 220V / 380V, 50 / 60Hz AC power into DC power through a rectifier circuit, and then converts the DC power into voltages of different frequencies through an internal control circuit. When current flows through the coil, a changing alternating magnetic field is generated. When the alternating magnetic lines of force in the magnetic field pass through the furnace inner wall 13, countless small eddy currents are generated on the furnace inner wall 13, causing the furnace inner wall 13 itself to heat up at high speed, thereby achieving the purpose of rapid heating.

[0052] To further improve the precision of chip sintering, a vertical guide rail 14 is installed on the top wall of the furnace body 1. The vertical guide rail 14 is in the shape of a hollow cylinder, and the inner wall of the vertical guide rail 14 is provided with a plurality of guide grooves. A slide post 21 is provided on the top of the upper workbench 2, and the outer wall of the slide post 21 is provided with a protrusion that matches the guide groove. The slide post 21 is inserted into the guide groove and slides with the guide groove. The cooperation between the vertical guide rail 14 and the slide post 21 ensures that the upper workbench 2 moves smoothly in the vertical direction. When the number of guide grooves is large and densely arranged, a structure similar to an internal gear is formed. Correspondingly, the outer wall of the slide post 2121 also has a large number of protrusions, forming a structure similar to a gear. The two structures match to achieve a precise guiding effect, thereby improving the processing accuracy of the chip.

[0053] After the chip sintering process is completed, a buffer is installed on the inner wall of the furnace body 1 to facilitate the return of the upper worktable 2. One end of the tension sensor 15 is connected to the buffer, and the other end of the tension sensor 15 is connected to the top of the slide post 21. The tension sensor 15 and the buffer are located within the vertical guide rail 14. The buffer not only provides a buffering effect but also facilitates the return of the upper worktable 2 when the magnetic field is absent or weakened. Preferably, the buffer is a spring.

[0054] To facilitate workpiece attachment and removal, the top surface of the lower workbench 3 is provided with mounting holes. The fixture also has corresponding through-holes, through which positioning rods pass to secure the fixture to the lower workbench 3. The fixture includes a sample stage for securing samples. Multiple samples can be placed on the sample stage, and the appropriate sample stage can be selected based on the sample's shape and size.

[0055] To further illustrate, the furnace body 1 is connected to a gas pipeline, and the gas pipeline is connected to a vacuum pump 63, a gas cylinder 62 and an overflow valve 64; in step (2), the vacuum pump 63 first makes the furnace body 1 reach a preset vacuum degree, and then adjusts the threshold of the overflow valve 64, and the gas cylinder 62 fills the furnace body 1 with protective gas; repeat 2-4 times. That is, the gas cylinder 62 repeatedly fills the furnace body 1 with protective gas 2-4 times to ensure that the air in the furnace is exhausted. Preferably, the threshold range of the overflow valve 64 is 0-10 atmospheres, and the vacuum degree in the furnace body 1 ranges from -200kPa to -50kPa to accommodate the processing of various chip products. It should be noted that the gas pipeline is also equipped with an air pressure indicator 61 for displaying the air pressure in the furnace body.

[0056] The present invention is further illustrated by the following examples.

[0057] Example 1

[0058] The chip sintering method of this embodiment uses a sintering furnace to sinter the chips. The sintering furnace includes a furnace body 1, an upper workbench 2, a lower workbench 3, and an electromagnetic control device 4. The lower workbench 3 is located directly below the upper workbench 2, and the upper workbench 2 can move vertically. A vertical guide rail 14 is installed on the top wall of the furnace body 1. The vertical guide rail 14 is hollow cylindrical and has a plurality of guide grooves on its inner wall. A slide post 21 is provided on the top of the upper workbench 2. The outer wall of the slide post 21 is provided with a protrusion matching the guide groove. The slide post 21 is inserted into the guide groove and slides with the guide groove. The top of the slide post 21 is connected to the top of the furnace body 1 via a tension sensor 15 and a buffer. The tension sensor 15 and the buffer are located inside the vertical guide rail 14. The furnace body includes a furnace outer wall 12 and a furnace inner wall 13. The space between the furnace outer wall 12 and the furnace inner wall 13 is filled with heat insulation material. The material of the furnace inner wall 13 is magnetic material. An electromagnetic heating coil is wrapped around the outer side of the furnace inner wall 13. The furnace body 1 is connected to a gas pipeline, which is connected to a vacuum pump 63, a gas cylinder 62 and a relief valve 64;

[0059] The method comprises the following steps:

[0060] (1) Coat a layer of copper paste on a 10 mm*10 mm large copper plate, then place a 3 mm*3 mm small copper plate on top of the copper paste to form a sandwich structure of large copper plate-copper paste-small copper plate. Place 16 workpieces on the sample stage of the fixture, and pass the positioning rod (screw) through the mounting hole of the lower workbench 3 and the through hole of the fixture to fix the fixture to the top surface of the lower workbench 3.

[0061] (2) Turn on the vacuum pump 63 to make the pressure in the furnace body 1 reach -75 kPa, set the threshold of the overflow valve 64 to 1.5 atmospheres, and fill the furnace body 1 with protective gas from the gas cylinder 62 containing hydrogen and argon. Repeat the process twice;

[0062] (3) The magnetic field generating device 31 in the lower workbench 3 generates a magnetic field. The upper workbench 2 made of magnetic material moves toward the lower workbench 3 under the action of the magnetic field and applies pressure to the workpiece on the lower workbench 3. The pressure applied by the upper workbench 2 to the workpiece is set to 60 kg. The pressure applied by the upper workbench 2 to the workpiece is obtained through the tension sensor 15. The magnetic field control device controls the intensity and shape of the magnetic field generated by the magnetic field generating device 31 according to the tension signal of the tension sensor 15.

[0063] (4) The electromagnetic control device 4 controls the heating temperature of the electromagnetic heating coil 11 to heat the interior of the furnace body 1 and sinter the workpiece. The heating rate in the furnace body 1 is less than or equal to 0.4°C / s.

[0064] The sintering temperature gradient is as follows:

[0065] The temperature in the furnace body 1 rises to 30-100°C and is kept warm for 2-8 minutes;

[0066] The temperature in furnace body 1 rises to 110-120°C and is kept warm for 7-13 minutes;

[0067] The temperature in furnace body 1 rises to 120-600℃ and keeps warm for 25-35 minutes;

[0068] (5) After sintering is completed, the pressure in the furnace body 1 is released, the door is opened, the fixture is removed, and the workpiece is taken out to obtain the sintered chip.

[0069] Example 2

[0070] The chip sintering method of this embodiment is basically the same as that of embodiment 1, with the following differences:

[0071] In step (1), a filler, namely solder, is filled into the micropores of a flexible copper clad laminate (FCCL) with micropores by screen printing. The FCCL has a total thickness of 66 μm, a 30 μm polyimide (PI) intermediate dielectric layer, and 18 μm copper foil on both sides. The micropore depth is approximately 50 μm, and the diameter of the micropore is approximately 35 μm.

[0072] Position the flexible copper clad laminate on the sample stage of the fixture, and pass the positioning rod (screw) through the mounting hole of the lower workbench 3 and the through hole of the fixture to fix the fixture to the top surface of the lower workbench 3;

[0073] In step (2), the pressure in the furnace body 1 is -100 KPa, the protective gas filled into the furnace body 1 is nitrogen, and the protective gas is repeatedly filled into the furnace body 1 4 times;

[0074] In step (3), the pressurization pressure is set to 20 kg;

[0075] In step (4), the heating rate in the furnace body 1 is less than or equal to 0.1°C / s, and the maximum temperature in the furnace body 1 does not exceed 250°C.

[0076] Other structures and operations of a chip sintering method according to an embodiment of the present invention are known to those skilled in the art and will not be described in detail here.

[0077] Throughout this specification, reference to terms such as "embodiment" or "example" indicates that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0078] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to the embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the claims and their equivalents.

Claims

1. A chip sintering method, characterized in that: The chip is sintered in a sintering furnace, the sintering furnace comprising a furnace body, an upper workbench and a lower workbench, the lower workbench being located directly below the upper workbench, and the upper workbench being movable vertically. The method comprises the following steps: (1) placing the workpiece on a fixture, and fixing the fixture to the top surface of the lower workbench; (2) introducing protective gas into the furnace body and adjusting the vacuum degree in the furnace body; (3) causing the magnetic field generating device in the lower workbench to generate a magnetic field, so that the upper workbench made of magnetic material moves toward the lower workbench under the action of the magnetic field and pressurizes the workpiece on the lower workbench; (4) The electromagnetic heating coil wound around the furnace body heats the furnace body, thereby increasing the temperature inside the furnace body and sintering the workpiece; (5) After sintering is completed, the furnace body is depressurized and the workpiece is taken out to obtain the sintered chip; A tension sensor is connected between the upper workbench and the inner wall of the furnace body, and the pressure applied by the upper workbench to the workpiece is obtained through the tension sensor; The magnetic field generating device is connected to an electromagnetic control device, and the electromagnetic control device controls the intensity and shape of the magnetic field generated by the magnetic field generating device according to the tension signal of the tension sensor.

2. The chip sintering method according to claim 1, characterized in that: The electromagnetic control device is connected to the electromagnetic heating coil, and the electromagnetic control device controls the heating temperature of the electromagnetic heating coil.

3. The chip sintering method according to claim 1, characterized in that: A vertical guide rail is installed on the top wall of the furnace body. The vertical guide rail is in a hollow cylindrical shape, and the inner wall of the vertical guide rail is provided with a plurality of guide grooves. A sliding column is provided on the top of the upper workbench, and a protrusion matching the guide groove is provided on the outer wall of the sliding column. The sliding column is inserted into the guide groove and slidably matched with the guide groove.

4. The chip sintering method according to claim 3, characterized in that: A buffer is provided on the inner wall of the furnace body, one end of the tension sensor is connected to the buffer, and the other end of the tension sensor is connected to the top of the sliding column; The tension sensor and the buffer are located in the vertical guide rail.

5. The chip sintering method according to claim 1, characterized in that: The furnace body is connected to a gas pipeline, and the gas pipeline is connected to a vacuum pump, a gas cylinder and an overflow valve; In the step (2), first, the vacuum pump is used to make the furnace body reach a preset vacuum degree, then the threshold value of the overflow valve is adjusted, and the gas cylinder is used to fill the furnace body with protective gas, and the filling of the furnace body with protective gas is repeated 2-4 times.

6. The chip sintering method according to claim 1, characterized in that: In the step (4), when the workpiece is a copper sheet welding structure, the heating rate in the furnace body is less than or equal to 0.4°C / s; The sintering temperature gradient is as follows: The temperature inside the furnace rises to 30-100°C and is kept warm for 2-8 minutes; The temperature in the furnace rises to 110-120°C and is kept warm for 7-13 minutes; The temperature inside the furnace rises to 120-600° C. and is kept warm for 25-35 minutes.

7. The chip sintering method according to claim 1, characterized in that: In the step (4), when the workpiece is a flexible copper-clad laminate with micropores, solder is filled in the micropores of the flexible copper-clad laminate with micropores, the heating rate in the furnace body is less than or equal to 0.1°C / s, and the maximum temperature in the furnace body does not exceed 250°C.

8. The chip sintering method according to claim 1, characterized in that: The furnace body comprises an outer wall and an inner wall, the space between the outer wall and the inner wall is filled with a heat-insulating material, and the material of the inner wall is a magnetic material; The electromagnetic heating coil is wound around the outer side of the inner wall of the furnace.

9. The chip sintering method according to claim 1, characterized in that: The top surface of the lower workbench is provided with a mounting hole; The clamp is provided with a through hole corresponding to the mounting hole, and the positioning rod passes through the mounting hole and the through hole so that the clamp is fixed to the lower workbench.

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