Soldering tip, soldering tip manufacturing system and soldering tip sintering method

Abstract

The present application provides a kind of soldering piece, soldering piece preparation system and soldering piece sintering method.Soldering piece includes: soldering piece body and multiple metal protrusions, multiple metal protrusions are respectively spaced apart in the first surface and the second surface of the soldering piece body, the spacing between any two adjacent metal protrusions in the multiple metal protrusions of the first surface and the second surface of the soldering piece body is 1-50 μm.Multiple metal protrusions are closely spaced by forming micro-nano structure on the first surface and the second surface of the soldering piece body, promote multiple metal protrusions and chip diffusion welding, so as to sinter at lower temperature, realize that soldering piece and chip can be uniformly and reliably connected in large area without organic matter.

Description

Technical Field

[0001] This invention relates to the field of electronic packaging technology, and in particular to a solder pad, a solder pad preparation system, and a solder pad sintering method. Background Technology

[0002] With the gradual maturation and application of third-generation semiconductors with superior performance, various industries have ushered in new development opportunities. From a materials perspective alone, it is difficult for alloy solders of various systems to simultaneously meet the requirements of low-temperature interconnection and high-temperature lead-free bonding. The various defects also make it difficult for alloy solders to be widely used. Due to the application limitations of common high-temperature solders, from a process perspective, there are currently two main research directions for achieving low-temperature interconnection: transient liquid phase sintering technology and nanopowder sintering bonding.

[0003] Transient liquid phase sintering (TPS) technology involves melting a low-melting-point metal placed between a high-melting-point metal and maintaining it in a liquid state for a sufficient time to allow for complete reaction and the formation of a high-melting-point intermetallic compound. Commonly used low-melting-point metals in TPS are tin (Sn) or indium (In), while high-melting-point metals include silver (Ag), gold (Au), copper (Cu), and nickel (Ni). Current research focuses on binary TPS systems, primarily Ag-Sn, Ag-In, Cu-Sn, Cu-In, and Ni-Sn.

[0004] Another method for achieving interconnection at relatively low temperatures is through sintering of nano-metal powders. This is because nanoparticles have high surface energy, making it possible to form effective connections through solid-state sintering at temperatures far below the melting points of metals. Furthermore, no brittle intermetallic compounds are formed after sintering, and the remelting temperature is relatively high. Therefore, nanoparticle sintering has been extensively studied. The main sintering materials are nano-silver and nano-copper, as both silver and copper possess good electrical and thermal conductivity, low elastic modulus, and excellent welding properties. The main step in this process is to mix nanoparticles with organic solvents, including solvents, dispersants, and binders, in a certain proportion to prepare a solder paste with certain fluidity and wettability for subsequent sintering.

[0005] The two technologies mentioned above are the mainstream technologies in sintering at present. They each have their own characteristics, but neither can achieve sintering at a low temperature, large-area uniform and reliable connection, and the absence of organic matter at the same time. Summary of the Invention

[0006] This invention provides a solder sheet, a solder sheet preparation system, and a solder sheet sintering method to solve the defects of the prior art that cannot simultaneously achieve low-temperature sintering, large-area uniform and reliable bonding, and the absence of organic matter.

[0007] This invention provides a solder pad, comprising:

[0008] Welding piece body;

[0009] Multiple metal protrusions are respectively and spaced apart on the first and second surfaces of the solder sheet body, and the distance between any two adjacent metal protrusions on the first and second surfaces of the solder sheet body is 1-50 μm.

[0010] According to the present invention, the height of each metal protrusion is 1-100 μm; the thickness of the solder sheet body is 10-3000 μm; and the ratio of the height of each metal protrusion to the thickness of the solder sheet body is 10-35%.

[0011] According to a solder pad provided by the present invention, the plurality of metal protrusions are spaced apart along a first direction and / or a second direction; the first direction and the second direction are arranged at an angle.

[0012] According to a solder pad provided by the present invention, the plurality of metal protrusions are uniformly spaced along a first direction and / or a second direction; the first direction and the second direction are perpendicular to each other.

[0013] The present invention also provides a solder pad preparation system for preparing the above-mentioned solder pads, the system comprising:

[0014] A straightening device is used to convey the metal strip used to prepare the weld sheet and to straighten the metal strip.

[0015] A laser processing apparatus is used to perform laser processing on the first and second surfaces of the metal strip respectively, so as to form a plurality of metal protrusions on the first and second surfaces of the metal strip that are the same as the structure of the weld sheet;

[0016] A packaging device for coating a protective layer onto the first and second surfaces of the metal strip after laser processing by the laser processing device;

[0017] A cutting device is used to cut the metal strip to form multiple weld sheets.

[0018] According to a solder pad preparation system provided by the present invention, the system further includes:

[0019] The first cleaning device is used to clean the first and second surfaces of the metal strip after laser processing by the laser processing device using acidic and alkaline solvents, respectively.

[0020] The second cleaning device is used to clean the residual acidic and / or alkaline solvents from the first and second surfaces of the metal strip.

[0021] A drying device for drying the first and second surfaces of the metal strip.

[0022] According to a solder pad preparation system provided by the present invention, the system further includes:

[0023] A curing device for curing the protective layer of the metal strip.

[0024] The present invention also provides a method for sintering solder pads, applied to sintering solder pads prepared by the above-mentioned solder pad preparation system, the method comprising:

[0025] Each of the weld sheets with the protective layer removed is sintered and connected in a preset temperature range using a sintering apparatus based on a first substrate and a second substrate, to obtain each sintered sample; the preset temperature range is 0-300℃.

[0026] According to a solder sheet sintering method provided by the present invention, the solder sheet with its protective layer removed is sintered and joined within a preset temperature range using a sintering apparatus based on a first substrate portion and a second substrate portion to obtain each sintered sample, comprising:

[0027] Each of the weld nuggets with the protective layer removed is placed between the first substrate portion and the second substrate portion within the sintering apparatus;

[0028] The initial state within the sintering apparatus is set; the initial state includes a first temperature of the first substrate portion and the second substrate portion, a first vacuum degree and a first pressure within the sintering apparatus; the first temperature is 30-90℃; the first vacuum degree is 0.001-0.01Pa; and the first pressure is 50-200Pa.

[0029] The first substrate portion and the second substrate portion in the sintering apparatus are heated to a second temperature, the first substrate portion and the second substrate portion in the sintering apparatus are kept at the second temperature for a first preset time, and when the temperature is raised to the second temperature, the pressure inside the sintering apparatus is increased to a second pressure to maintain the second pressure for the first preset time.

[0030] The sintering apparatus is controlled to stop pressurizing and heating, and the sintered sample consisting of the first substrate, the second substrate, and the solder sheet is allowed to cool.

[0031] According to a solder sheet sintering method provided by the present invention, after setting the initial state within the sintering apparatus, the method further includes:

[0032] The first substrate portion and the second substrate portion in the sintering apparatus are heated to a third temperature, and the first substrate portion and the second substrate portion in the sintering apparatus are kept at the third temperature for a second preset time.

[0033] The solder pad, solder pad preparation system, and solder pad sintering method provided by this invention utilize multiple metal protrusions spaced apart on the first and second surfaces of the solder pad body, with the spacing between any two adjacent metal protrusions being 1-50 μm. This forms a micro / nano structure with multiple metal protrusions closely spaced on the first and second surfaces of the solder pad body. This facilitates diffusion bonding between the multiple metal protrusions and the chip during the solder pad-chip sintering process, enabling sintering at lower temperatures and achieving a large-area, uniform, and reliable connection between the solder pad and the chip, without the presence of organic matter. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0035] Figure 1 This is a schematic diagram of the structure of the welding sheet provided by the present invention;

[0036] Figure 2 These are the front view, right view, and top view of a solder sheet according to an embodiment of the present invention;

[0037] Figure 3 These are front, right, and top views of a solder sheet according to another embodiment of the present invention;

[0038] Figure 4 This is a schematic diagram of the structure of the solder sheet preparation system provided by the present invention;

[0039] Figure 5 This is a schematic diagram of the structure of the laser processing device provided by the present invention;

[0040] Figure 6 The image shows a scanning electron microscope (SEM) image of the micro / nano structure of multiple cuboid-shaped protrusions on the copper foil strip of the present invention after laser processing by a laser processing device.

[0041] Figure 7 The image shows a scanning electron microscope (SEM) image of the micro / nano structure of multiple conical protrusions on the copper foil strip of the present invention after laser processing by a laser processing device.

[0042] Figure 8 This is a schematic diagram of the structure of the present invention, which involves coating the solder sheet with UV adhesive;

[0043] Figure 9 This is a schematic diagram of the process of cutting the solder sheet, removing the UV adhesive, transferring the solder sheet, attaching the sheet, and placing it into the sintering device according to the present invention;

[0044] Figure 10 This is a schematic diagram of the sintering apparatus provided by the present invention;

[0045] Figure 11 This is one of the flowcharts illustrating the sintering method for weld sheets provided by the present invention;

[0046] Figure 12 This is the second schematic diagram of the sintering method for the weld sheet provided by the present invention;

[0047] Figure 13 This is the third schematic diagram of the sintering method for weld sheets provided by the present invention;

[0048] Figure 14 This is the temperature curve during the sintering of the solder sheet provided by the present invention. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0050] Please refer to Figure 1 The present invention provides a solder pad 50, comprising: a solder pad body 51 and a plurality of metal protrusions 511.

[0051] In order to achieve sintering connection with the surface of the chip (such as a diode chip), the solder pad body 51 can be a sheet-like component made of a metal material with a melting point lower than or equal to that of the chip, such as copper or silver.

[0052] To achieve low-temperature sintering, large-area uniform and reliable bonding, and the absence of organic matter, this embodiment of the invention provides a plurality of metal protrusions 511 spaced apart on the first and second surfaces of the solder sheet body 51. The solder sheet body 51 and the metal protrusions 511 are made of the same material. The distance between any two adjacent metal protrusions 511 is 1-50 μm. It should be noted that the first and second surfaces can be two surfaces on the solder sheet body 51 that are in opposite positions. For example, the first surface can be the lower surface of the solder sheet body 51, and the second surface can be the upper surface of the solder sheet body 51.

[0053] Multiple metal protrusions 511 are spaced apart on the first and second surfaces of the solder pad body 51. The spacing between any two adjacent metal protrusions 511 is 1-50 μm. This micro-nano structure, with multiple metal protrusions 511 closely spaced on the first and second surfaces of the solder pad body 51, allows for the formation of "connection points" with the chip surface under heating and pressurization during the sintering connection of the solder pad body 51 and the chip. At each "connection point," each metal protrusion 511 forms a stable covalent bond with the chip surface. This structure of multiple metal protrusions 511 expands the contact area with the chip surface, achieving a large-area, uniform, and reliable connection. Furthermore, the structure of multiple metal protrusions 511 reduces the sintering temperature, allowing sintering of the solder pad 50 and the chip to be achieved at temperatures below 300 degrees Celsius. Therefore, this embodiment of the invention achieves low-temperature sintering, a large-area, uniform, and reliable connection, and is free of organic matter.

[0054] By spaced-apart metal protrusions 511 on the first and second surfaces of the solder pad body 51, with the spacing between any two adjacent metal protrusions 511 being 1-50 μm, a micro / nano structure of closely spaced metal protrusions 511 is formed on the first and second surfaces of the solder pad body 51. This facilitates diffusion bonding between the metal protrusions 511 and the chip during the sintering connection of the solder pad 50 and the chip, enabling sintering at lower temperatures and achieving a large-area, uniform, and reliable connection between the solder pad 50 and the chip, without the presence of organic matter.

[0055] In other aspects of this invention, the height of each metal protrusion 511 is 1-100 μm; the thickness of the solder pad body 51 is 10-3000 μm; and the ratio of the height of each metal protrusion 511 to the thickness of the solder pad body 51 is 10-35%. Specifically, the height of each metal protrusion 511 is the same on both the first and second surfaces of the solder pad body 51. When the ratio of the height of each metal protrusion 511 to the thickness of the solder pad body 51 is set to 10-35%, the solder pad 50 and the chip can achieve a better sintering connection, improving the stability of the connection between the solder pad 50 and the chip.

[0056] Furthermore, it is understandable that the metal protrusion 511 can be of various shapes. For example, the metal protrusion 511 can be a cuboid, cylinder, cone, frustum, etc. Please refer to [reference needed]. Figure 2 When the metal protrusion 511 is cuboid in shape, the width and height of the cuboid can be set to a range of 1-100 μm, with the width-to-height ratio ranging from 0.1 to 10. Please refer to... Figure 3 When the metal protrusion 511 is conical, the diameter of the cone can be set to a range of 1-100μm, the height to a range of 100μm, and the ratio of diameter to height to a range of 0.1-10.

[0057] In other aspects of the embodiments of the present invention, the plurality of metal protrusions 511 are spaced apart along a first direction and / or a second direction; the first direction and the second direction are angled. For example, the plurality of metal protrusions 511 may be spaced apart along the first direction. In this case, the first direction may be a horizontal direction. Alternatively, the plurality of metal protrusions 511 may be spaced apart along the second direction. In this case, the second direction may be a vertical direction perpendicular to the horizontal direction. Alternatively, the plurality of metal protrusions 511 may be spaced apart along the first direction and the second direction. In this case, the first direction and the second direction may be angled, such as the first direction and the second direction being perpendicular to each other. Of course, the first direction and the second direction may also be at an acute angle or an obtuse angle. By setting the plurality of metal protrusions 511 spaced apart along the first direction and / or the second direction, the regularity of the arrangement of the plurality of metal protrusions 511 on the first surface and the second surface of the solder pad body 51 is improved, which facilitates the formation of more regular "connection points" for multiple metal diffusion soldering, and further improves the stability of the large-area connection between the solder pad 50 and the chip surface.

[0058] In other aspects of the embodiments of the present invention, the plurality of metal protrusions 511 are uniformly spaced along a first direction and / or a second direction. The first direction and the second direction are perpendicular to each other. Specifically, the plurality of metal protrusions 511 may be uniformly spaced along the first direction. In this case, the first direction may be a horizontal direction. Alternatively, the plurality of metal protrusions 511 may be uniformly spaced along the second direction. In this case, the second direction may be a vertical direction perpendicular to the horizontal direction. Alternatively, the plurality of metal protrusions 511 may be uniformly spaced along the first direction and the second direction. In this case, the first direction and the second direction are perpendicular to each other. For example, please refer to... Figure 2 , Figure 2 In this configuration, multiple cuboid-shaped metal protrusions 511 can be evenly spaced along a horizontal direction and a vertical direction perpendicular to the horizontal direction. Alternatively, please refer to... Figure 3 , Figure 3 In the middle, multiple conical metal protrusions 511 can be evenly spaced along the horizontal direction and the vertical direction perpendicular to the horizontal direction.

[0059] By setting multiple metal protrusions 511 evenly spaced along a first direction and / or a second direction, the regularity of the arrangement of the multiple metal protrusions 511 is further improved, forming multiple more uniformly arranged "connection points" for metal diffusion welding, thereby improving the large-area uniform sintering connection between the solder pad 50 and the chip surface. This further improves the stability of the large-area connection between the solder pad 50 and the chip surface.

[0060] Please refer to Figure 4 The present invention also provides a solder sheet preparation system 100 for preparing the above-mentioned solder sheet 50. The system includes: a straightening device 3, a laser processing device 5, a packaging device 10, and a cutting device (not shown).

[0061] The straightening device 3 is used to convey the metal strip used to prepare the weld sheet 50 and to straighten the metal strip. The metal strip is the strip used as raw material to prepare the weld sheet 50; for example, the metal strip can be a metal foil. The metal foil has a thickness ranging from 10-3000 μm and a width ranging from 10-900 mm, and its material can be a single metal such as Ag, Cu, In, Sn, or an alloy thereof. Specifically, the straightening device 3 can be a straightening roller assembly. The straightening roller assembly can be used to convey and straighten the metal foil and release residual stress in the metal foil using minute mechanical deformation. In one embodiment, the straightening roller assembly includes multiple pairs of staggered rollers, with the number of roller pairs ranging from 3 to 10. Each pair of rollers is made of stainless steel and uses minute deformation to straighten and straighten the metal foil and mechanically release residual stress in the foil.

[0062] It should be noted that a device for releasing the metal strip is usually installed upstream of the straightening device 3, such as a strip-releasing reel 1. The strip-releasing reel 1 holds a bundle of metal foil strip, which is used to release the foil strip to be processed. Downstream of the strip-releasing reel 1, an adjusting device 2 can be installed. The adjusting device 2 has a pressure roller connected to a spring, which applies downward pressure to the metal foil strip to prevent it from slackening during operation.

[0063] The laser processing device 5 is used to perform laser processing on the first surface and the second surface of the metal strip respectively, so as to form a plurality of metal protrusions 511 with the same structure as the welding sheet 50 on the first surface and the second surface of the metal strip respectively.

[0064] In one embodiment, please refer to Figure 5 The laser processing apparatus 5 includes galvanometers 13 and 20 for controlling the laser processing path, entrance windows 14 and 19, evacuation port 15, air inlet 16, rubber roller assembly 17 for transferring metal foil strip, and vacuum gauge 18 for detecting the vacuum level of the cavity.

[0065] Specifically, the straightened and corrected metal foil strip is transferred into the cavity of the laser processing device 5 by a rubber roller assembly. The rubber rollers have a certain elasticity to ensure the sealing of the cavity of the laser processing device 5, preventing air leakage during vacuuming and gas filling. The laser processing device 5 starts the laser and uses galvanometers 13 and 20 to process the micro-nano structure of multiple metal protrusions 511 on the first and second surfaces of the aforementioned welding sheet 50 on the surface of the metal foil strip, and then it is transferred out by the rubber roller assembly. For example, when the multiple metal protrusions 511 on the first and second surfaces of the welding sheet 50 are multiple cuboid-shaped bosses, the width of the cuboid-shaped bosses can be set to 75 μm and the height to 50 μm. The multiple cuboid-shaped bosses are evenly spaced along the horizontal and vertical directions, and the spacing between each adjacent cuboid shape is 25 μm. When the multiple metal protrusions 511 are multiple conical protrusions, the diameter of the conical protrusions can be set to 35 μm, the height to 50 μm, and the spacing to 30 μm. Please refer to... Figure 6 and Figure 7 , Figure 6 The image shows a scanning electron microscope (SEM) image of the micro / nano structure of multiple cuboid-shaped protrusions after the copper foil strip has undergone laser processing by the laser processing device 5. Figure 7 The image shows a scanning electron microscope (SEM) image of a copper foil strip after laser processing by laser processing device 5, depicting a micro / nano structure of multiple conical protrusions. The copper foil strip is then rotated out by a rubber roller assembly after laser processing. Furthermore, the feeding speed of the metal foil strip by laser processing device 5 can range from 0.1 to 1000 cm / min. The laser power of laser processing device 5 ranges from 5 to 95 W, and the pulse width is 1 × 10⁻⁶. -11 -1×10 -15 The laser processing device 5 has a laser switching function, the laser spot movement speed can be changed in real time, and the laser processing range can cover the entire width of the metal foil strip.

[0066] In addition, before fabricating the welding sheet 50, the laser processing device 5 is turned on. The processing is carried out under atmospheric conditions or under a protective atmosphere. When the processing is carried out under a protective atmosphere, the cavity of the laser processing device 5 is first evacuated to a vacuum level of 0-1×10⁻⁶. -4 Pa, then air or inert gas is introduced into the cavity of the laser processing device 5. The inert gas can be argon, helium, nitrogen, carbon dioxide, etc., and the gas pressure is 100-1×10000Pa.

[0067] Packaging device 10 is used to coat the first and second surfaces of the metal strip after laser processing by the laser processing device 5 with a protective layer. Specifically, packaging device 10 can be a coating machine. The metal foil strip is coated using a coating machine. The coating machine contains uncured UV adhesive for coating the first and second surfaces of the metal foil strip to prevent oxidation. Please refer to... Figure 8The coating thickness of UV adhesive applied to both sides of the metal foil strip is 100-500μm.

[0068] The cutting device is used to cut the metal strip into multiple weld pieces 50. Specifically, after the metal foil strip processed and packaged by the packaging device 10, it is cut into multiple weld pieces 50 of appropriate size and pattern using a shearing machine or laser. It should be noted that the metal strip can also be cut into arbitrary shapes by the cutting device to meet the requirements of personalized design graphics.

[0069] In this embodiment of the invention, a straightening device 3 straightens and corrects the metal strip and conveys it to a laser processing device 5. In the laser processing device 5, an ultrafast laser processes the first and second surfaces of the metal strip. By adjusting the laser process and processing path, a micro / nano structure of multiple metal protrusions 511, such as a solder pad 50, is generated on the first and second surfaces of the metal strip. The strip is then transported to a packaging device 10 to coat it with a protective layer to prevent oxidation. Finally, a cutting device is used to pattern and prepare the target solder pad 50 shape. Thus, the laser processing device 5 processes a micro / nano structure of multiple metal protrusions 511, such as a solder pad 50, on the metal strip. This promotes diffusion bonding of the multiple metal protrusions 511 to the chip surface, enabling sintering at a lower temperature and achieving a large-area, uniform, and reliable connection between the solder pad body 51 and the chip, without the presence of organic matter.

[0070] Alternatively, sintered samples can be prepared with the weld nuggets. During sintering, the UV adhesive on the first and second surfaces of each weld nugget 50 is peeled off, and the nugget is placed directly on the sintering area of ​​the sintering apparatus 21. Please refer to... Figure 9 For example, a rectangular metal foil strip is cut by a shearing machine or laser cutting to obtain multiple square-shaped solder pads 50. The UV adhesive on the first and second surfaces of each solder pad 50 is removed, and the solder pads 50 are transferred and mounted. During mounting, the solder pads 50 are placed between the first substrate portion 52 and the second substrate portion 53. The sample structure composed of the solder pads 50, the first substrate portion 52, and the second substrate portion 53 is fed into the sintering apparatus 21 via a take-up reel 12, awaiting sintering.

[0071] Please refer to Figure 10During solder sheet sintering, the sintering apparatus 21 is used to sinter and connect each solder sheet 50 with the protective layer (UV adhesive) removed, based on the first substrate portion 52 and the second substrate portion 53, to obtain each sintered sample. Specifically, the sintering apparatus 21 may be a pressurizing device. Specifically, before sintering begins, the sample structure consisting of the solder sheet 50, the first substrate portion 52, and the second substrate portion 53 is placed on the lower heating plate of the sintering apparatus 21. The second substrate portion 53 is heated by the upper heating plate, and the first substrate portion 52 is heated by the lower heating plate. Any remaining UV adhesive is volatilized using atmospheric oxygen. The heating temperature is 80-200°C (e.g., 160°C), and the heating time is 5-15 minutes. Subsequently, the cavity inside the sintering apparatus 21 is evacuated. The vacuum degree is 1×10⁻⁶. -2 ×10 -4 When the pressure reaches 50 MPa, the mechanical pump is turned off, and nitrogen is introduced for sintering. The pressurization device is then activated, with a pressure range of 0-30 MPa (e.g., 10 MPa) and a heating temperature range of 0-280°C (e.g., 250°C). During sintering, an inert gas, such as argon, helium, nitrogen, or carbon dioxide, is continuously introduced. After heating and pressurization, the sample is cooled in an inert gas environment at a pressure of 0.01-1000 Pa until the sample temperature drops below 100°C. The sintered sample, consisting of the first substrate portion 52, the second substrate portion 53, and the solder sheet 50, is then removed and cooled at room temperature. This yields each sintered sample.

[0072] In other aspects of the embodiments of the present invention, the system further includes: a first cleaning device, a second cleaning device 8, and a drying device 9.

[0073] The first cleaning device is used to clean the first and second surfaces of the metal strip after laser processing by the laser processing device 5 using acidic and alkaline solvents, respectively. Specifically, the first cleaning device can be an ultrasonic cleaner. The ultrasonic cleaner includes an acid pickling tank 6 containing acidic solvent and an alkaline pickling tank 7 containing alkaline solvent, through which the metal foil strip is cleaned.

[0074] The second cleaning device 8 is used to clean residual acidic and / or alkaline solvents from the first and second surfaces of the metal strip. Specifically, the second cleaning device 8 can be a spray tank, which uses anhydrous ethanol or acetone to clean residual acidic and / or alkaline solvents from the surface of the metal foil strip.

[0075] The drying device 9 is used to dry the first and second surfaces of the metal strip. Specifically, the drying device 9 blows hot air from a porous air outlet to dry the anhydrous ethanol or acetone on the surface of the metal strip.

[0076] It should be noted that the tanks of the first cleaning device and the air drying device 9 can be preheated before the welding sheet 50 is made.

[0077] The metal strip is cleaned by acid and alkali washing using a first cleaning device, by cleaning residual acidic and / or alkaline solvents using a second cleaning device 8, and by drying using a drying device 9. This process ensures the purity of the metal strip surface.

[0078] In other aspects of embodiments of the present invention, the system further includes:

[0079] The curing device 11 is used to cure the protective layer of the metal strip. Specifically, the curing device 11 can be a photocuring device used to irradiate with high-intensity ultraviolet light to cure the UV adhesive coated on the surface of the metal foil strip. This prevents the UV adhesive on the metal foil strip from peeling off during transport.

[0080] For other aspects of the embodiments of the present invention, please refer to Figure 4 The system also includes: laser rangefinders 4, 4', 4"; laser rangefinders 4, 4', 4" are used to measure the distance between the bottom end of laser rangefinders 4, 4', 4" and the metal foil strip; when the front and rear rollers of laser rangefinders 4, 4', 4" rotate at different speeds, the metal foil strip will deform, causing the distance between laser rangefinders 4, 4', 4" and the foil strip to change; when the change in the distance between the bottom end of laser rangefinders 4, 4', 4" and the metal foil strip exceeds ±5%, an alarm will be triggered.

[0081] Please refer to Figure 11 The present invention also provides a method for sintering solder pads, applied to sintering solder pads prepared by the above-mentioned solder pad preparation system 100, the method comprising:

[0082] Step 100: Using a sintering apparatus 21, each of the weld pieces 50 with the protective layer removed is sintered and connected within a preset temperature range based on the first substrate portion 52 and the second substrate portion 53 to obtain each sintered sample. The preset temperature range is 0-300°C.

[0083] The first substrate portion 52 and the second substrate portion 53 are used for sintering connection with the solder sheet 50. The first substrate portion 52 and the second substrate portion 53 can be plate-shaped components made of various metal materials, such as copper plates, silver-plated copper plates, etc.

[0084] Specifically, the first substrate 52 uses a 10mm*10mm*2mm copper plate as the lower substrate, and the second substrate 53 uses a 3mm*3mm*2mm copper plate as the upper substrate. A rectangular metal foil strip is cut by a shearing machine or laser cutting to obtain multiple square-shaped solder pads 50. The UV adhesive on the first and second surfaces of each solder pad 50 is removed, and the solder pads 50 are transferred and mounted. During mounting, the solder pads 50 are placed between the first substrate 52 and the second substrate 53. The sample structure composed of the solder pads 50, the first substrate 52, and the second substrate 53 is fed into the sintering apparatus 21 for sintering. The sintering apparatus 21 heats and pressurizes within a preset temperature range of 0-300℃, causing the solder pads 50 to form "connection points" with the surface of the first substrate 52 (or the second substrate 53) through diffusion welding with multiple metals. At each "connection point," each metal protrusion 511 forms a stable covalent bond connection with the surface of the first substrate 52.

[0085] Thus, in this embodiment of the invention, when the solder sheet 50 is sintered by the sintering apparatus 21 with the first substrate portion 52 and the second substrate portion 53 in a preset temperature range of 0-300°C, the plurality of metal protrusions 511 are promoted to diffusely weld to the surfaces of the first substrate portion 52 and the second substrate portion 53 respectively. This enables sintering at a lower temperature, achieving a large-area uniform and reliable connection between the solder sheet 50 and the first substrate portion 52 and the second substrate portion 53, and without the presence of organic matter.

[0086] For other aspects of the embodiments of the present invention, please refer to Figure 12 Step 100, the sintering of each of the weld pieces 50 with the protective layer removed using the sintering apparatus 21 based on the first substrate portion 52 and the second substrate portion 53 within a preset temperature range to obtain each sintered sample, includes:

[0087] Step 110: Place each of the solder pieces 50 with the protective layer removed between the first substrate portion 52 and the second substrate portion 53 within the sintering apparatus 21.

[0088] Each of the weld nuggets 50, from which the protective layer has been removed, is placed between the first substrate portion 52 and the second substrate portion 53 within the sintering apparatus 21 using tools such as robotic arms.

[0089] Step 120: Set the initial state within the sintering apparatus 21; the initial state includes the first temperature of the first substrate portion 52 and the second substrate portion 53, the first vacuum degree and the first pressure within the sintering apparatus 21; the first temperature is 30-90℃; the first vacuum degree is 0.001-0.01Pa; and the first pressure is 50-200Pa.

[0090] Specifically, the first temperature of the first substrate portion 52 and the second substrate portion 53 within the sintering apparatus 21 can be set to 60°C. The first vacuum degree within the sintering apparatus 21 is 2 × 10⁻⁶. -3 Pa, then nitrogen gas is introduced into the equipment to bring the first pressure to 100 Pa.

[0091] Step 140: Control the first substrate portion 52 and the second substrate portion 53 in the sintering apparatus 21 to heat up to a second temperature, control the first substrate portion 52 and the second substrate portion 53 in the sintering apparatus 21 to maintain the second temperature for a first preset time, and control the pressure inside the sintering apparatus 21 to be increased to a second pressure when the temperature is raised to the second temperature, so as to maintain the second pressure for the first preset time.

[0092] Specifically, when the first substrate portion 52 and the second substrate portion 53 in the sintering apparatus 21 are heated to 250°C, pressure is applied, and the first substrate portion 52 and the second substrate portion 53 in the sintering apparatus 21 are kept at 250°C for 15 minutes, and the second pressure in the sintering apparatus 21 is kept at 10 MPa during the 15 minutes.

[0093] Step 150: Control the sintering apparatus 21 to stop pressurizing and heating, and wait for the sintered sample composed of the first substrate portion 52, the second substrate portion 53 and the solder sheet 50 to cool down.

[0094] After holding the second temperature of 250°C for 15 minutes, the pressurized heating is stopped. The sintered sample is then cooled under nitrogen atmosphere, with the pressure controlled at 5 Pa, until the temperature of the sintered sample drops below 100°C. After sintering, the nitrogen cylinder and the packaging equipment are turned off, and the sintered sample consisting of the first substrate part 52, the second substrate part 53 and the solder sheet 50 is taken out and cooled at room temperature.

[0095] Thus, in this embodiment of the invention, a laser processing device 5 processes a micro / nano structure of multiple metal protrusions 511, such as a weld sheet 50, on a metal strip. When the sintering device 21 sinters the weld sheet 50 through the first substrate portion 52 and the second substrate portion 53, it promotes the diffusion welding of the multiple metal protrusions 511 to the surfaces of the first substrate portion 52 and the second substrate portion 53, thereby achieving sintering at a relatively low temperature of 0-280°C. This enables a large-area, uniform, and reliable connection between the weld sheet 50 and the first substrate portion 52 and the second substrate portion 53, and the weld sheet 50 is free of organic matter.

[0096] For other aspects of the embodiments of the present invention, please refer to Figure 13 After step 120, setting the initial state within the sintering apparatus 21, the process further includes:

[0097] Step 130: Control the first substrate portion 52 and the second substrate portion 53 in the sintering apparatus 21 to heat up to a third temperature, and control the first substrate portion 52 and the second substrate portion 53 in the sintering apparatus 21 to maintain the third temperature for a second preset time.

[0098] Please refer to Figure 14 , Figure 14 This shows the temperature profile during the sintering of the solder sheet 50. Before sintering at a second temperature of 250°C, the first substrate portion 52 and the second substrate portion 53 within the sintering apparatus 21 are heated to a third temperature, and the first substrate portion 52 and the second substrate portion 53 within the sintering apparatus 21 are held at the third temperature for a second preset duration. The third temperature is 80-200°C, thereby evaporating any UV adhesive that may remain on the surface of the solder sheet 50. Specifically, the heating plates within the sintering apparatus 21 that heat the first substrate portion 52 and the second substrate portion 53 are heated at a rate of 20°C / min, and held at 160°C for 5 minutes to evaporate any UV adhesive that may remain on the surface of the solder sheet 50, ensuring the purity of the resulting sintered sample.

[0099] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A solder pad, characterized in that, include: Welding piece body; Multiple metal protrusions are respectively and spaced apart on the first and second surfaces of the solder sheet body. The distance between any two adjacent metal protrusions on the first and second surfaces of the solder sheet body is 1-50 μm, so as to realize a micro-nano structure in which multiple metal protrusions are closely spaced on the first and second surfaces of the solder sheet body.

2. The solder sheet according to claim 1, characterized in that, The height of each metal protrusion is 1-100 μm; the thickness of the solder pad body is 10-3000 μm; and the ratio of the height of each metal protrusion to the thickness of the solder pad body is 10-35%.

3. The solder sheet according to claim 1, characterized in that, The plurality of metal protrusions are spaced apart along a first direction and / or a second direction; the first direction and the second direction are angled together.

4. The solder sheet according to claim 3, characterized in that, The plurality of metal protrusions are evenly spaced along a first direction and / or a second direction; the first direction and the second direction are perpendicular to each other.

5. A solder sheet preparation system, characterized in that, The system for preparing the solder sheet according to any one of claims 1 to 4, the system comprising: A straightening device is used to convey the metal strip used to prepare the weld sheet and to straighten the metal strip. A laser processing apparatus is used to perform laser processing on the first surface and the second surface of the metal strip respectively, so as to form a plurality of metal protrusions on the first surface and the second surface of the metal strip, which are the same as the structure of the weld sheet; and to provide a micro-nano structure with closely spaced plurality of metal protrusions on the first surface and the second surface of the weld sheet body respectively. A packaging device for coating a protective layer onto the first and second surfaces of the metal strip after laser processing by the laser processing device; A cutting device is used to cut the metal strip to form multiple weld sheets.

6. The solder sheet preparation system according to claim 5, characterized in that, The system also includes: The first cleaning device is used to clean the first and second surfaces of the metal strip after laser processing by the laser processing device using acidic and alkaline solvents, respectively. The second cleaning device is used to clean the residual acidic and / or alkaline solvents from the first and second surfaces of the metal strip. A drying device for drying the first and second surfaces of the metal strip.

7. The solder sheet preparation system according to claim 5, characterized in that, The system also includes: A curing device for curing the protective layer of the metal strip.

8. A method for sintering solder sheets, characterized in that, The method is applied to sintering a weld sheet prepared by the weld sheet preparation system according to any one of claims 5 to 7, the method comprising: Each of the weld sheets with the protective layer removed is sintered and connected in a preset temperature range using a sintering apparatus based on a first substrate and a second substrate, to obtain each sintered sample; the preset temperature range is 0-300℃.

9. The sintering method for weld sheets according to claim 8, characterized in that, The process involves sintering each of the weld sheets with the protective layer removed using a sintering apparatus, based on a first substrate and a second substrate, within a preset temperature range to obtain each sintered sample, including: Each of the weld nuggets with the protective layer removed is placed between the first substrate portion and the second substrate portion within the sintering apparatus; The initial state within the sintering apparatus is set; the initial state includes a first temperature of the first substrate portion and the second substrate portion, a first vacuum degree and a first pressure within the sintering apparatus; the first temperature is 30-90℃; the first vacuum degree is 0.001-0.01Pa; and the first pressure is 50-200Pa. The first substrate portion and the second substrate portion in the sintering apparatus are heated to a second temperature, the first substrate portion and the second substrate portion in the sintering apparatus are kept at the second temperature for a first preset time, and when the temperature is raised to the second temperature, the pressure inside the sintering apparatus is increased to a second pressure to maintain the second pressure for the first preset time. The sintering apparatus is controlled to stop pressurizing and heating, and the sintered sample consisting of the first substrate portion, the second substrate portion, and the solder sheet is allowed to cool.

10. The sintering method for weld sheets according to claim 9, characterized in that, After setting the initial state within the sintering apparatus, the method further includes: The first substrate portion and the second substrate portion in the sintering apparatus are heated to a third temperature, and the first substrate portion and the second substrate portion in the sintering apparatus are kept at the third temperature for a second preset time.

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