A method of friction butt welding of dissimilar materials with a performance gap

Abstract

A kind of performance disparity material friction butt welding column planting method, it is related to microelectronic packaging technical field, to solve the problems such as high mould cost, poor universality of traditional column planting method of CGA package, no die embedded column planting no upsetting action, form flash gap, column strength and density are limited.First, the end of soldering column hot-dip tinning, print soldering paste on array pad and heat to form array spherical crown-shaped filler interconnection, milling into array filler boss;Soldering column tin coating end is loaded in precision drilling machine chuck claw, after centering with the column to be planted pad, preheat filler boss / soldering column tin coating at rotating speed n1, feed to predetermined down pressure with rotating speed n2 and axial speed V, stop soldering column rotation and apply upsetting displacement S2 to filler boss, then cool down, the friction butt welding column planting of single tin coating soldering column is completed under the action of friction heat-upsetting;Realize the friction butt welding column planting on array pad one by one under the same parameters.Used for CGA device column planting and similar shape performance part connection.

Description

Technical Field

[0001] This invention relates to the field of microelectronic packaging technology, and more specifically to a friction butt bonding method for bonding pillars between materials with significantly different properties. Background Technology

[0002] Column Grid Array (CGA) packaging, as the preferred packaging technology for high-frequency, high-power, high-I / O, and large-chip devices, has been widely used in aerospace, communications, military, and automotive electronics fields since its inception. This is because the taller solder pillars effectively improve heat dissipation during power cycling and alleviate stress caused by the difference in thermal expansion coefficients between the chip carrier substrate and the printed circuit board, resulting in extremely high thermal fatigue reliability. However, the array arrangement, positioning, and connection of solder pillars with large aspect ratios and poor stability are extremely difficult. The traditional pillar placement method, which uses molds to position copper pillars and reflow soldering for connection, suffers from problems such as high precision mold costs, poor mold versatility, easy scratching of solder pillars when removing the mold after soldering, the presence of the mold during the soldering process affecting the effective heat transfer of the heat source and the dissipation of flux gas in the solder paste, high porosity, and poor wettability.

[0003] Existing methods for mounting CGA packages without mold-assisted positioning involve using a miniature precision drilling machine to clamp the mounting post and align it with solder balls on an array of pads on the substrate. The post is then rotated at a specific speed and pressed down to drill into the solder balls to a predetermined depth. Positioning and connection of the post are achieved through frictional heat and force between the post and the solder balls, aiming to achieve moldless mounting. This moldless mounting method eliminates the need to customize a high-precision mold for each array size, significantly reducing costs and making it suitable for automated production of various CGA device sizes. However, further research has revealed the following problems with this moldless mounting method:

[0004] (1) The brazing ball without peripheral radial constraint softens due to friction heating and has low elastic clamping force and adhesion force to the embedded brazing post, resulting in low strength of the post connection.

[0005] (2) Insufficient clamping force and limited effect of pressure restraint measures result in the formation of non-dense brazing filler metal microstructure in the near-interface region, leading to low strength of the post connection.

[0006] (3) After the solder ball is inserted into the solder column, a solder "flash" will be formed on the top of the solder ball. The sharp notch of the "flash" can become a potential crack source during service, which can easily lead to accelerated thermal fatigue failure of the device.

[0007] (4) The scallop-shaped interface connection layer formed by atomic interdiffusion at the interface of brazing filler metal / brazing post with vastly different properties is easily ground away. The residual interface connection layer after welding is too thin and discontinuous, resulting in low strength of the post connection.

[0008] (5) Existing moldless pillar planting methods all use the rotating friction of the pillar to embed the solder balls on the array pads. This is an embedded friction welding method. In order to ensure the embedding depth and the rigidity of the pillar during planting, the exposed end length of the pillar during mounting cannot be too small, and the diameter of the pillar cannot be too small. This results in the large diameter of the pads and the solder balls on them, which affects the packaging density. Summary of the Invention

[0009] This invention addresses the problems of high precision mold costs and poor versatility in existing mold-assisted positioning and mounting methods for CGA device array bonding pillars. It also addresses the issues of sharp "flash" notches on the solder balls acting as crack sources and accelerating thermal fatigue failure in existing moldless embedded friction bonding pillar methods for CGA device array bonding pillars; low packaging density caused by the diameter of the bonding pillars being limited by the implantation depth and bonding pillar stiffness; connection quality limitations due to the grinding away of the scallop-shaped connection layer at the solder / bonding pillar interface during connection, resulting in an excessively thin and discontinuous interface connection layer after soldering, thus limiting connection strength; and the low elastic clamping and adhesion force of the solder balls without peripheral radial constraints on the embedded bonding pillars, coupled with limited effectiveness of pressure constraint measures, leading to the formation of non-dense solder microstructure in the near-interface region, thus limiting the bonding pillar connection strength.

[0010] A method for friction butt welding of inserts between materials with significantly different properties includes the following steps:

[0011] Step 1: Fabrication of the tin coating at the end of the solder column:

[0012] Standard-sized solder pillars are ultrasonically cleaned in an alcohol solution, then the ends of the solder pillars are dipped in flux, and then a tin-containing coating of a certain height is formed at the ends of the solder pillars using a hot-dip tinning method. Finally, they are ultrasonically cleaned again with an alcohol solution.

[0013] Step 2: Print an appropriate amount of solder paste onto the array of pads;

[0014] Step 3: Heat the solder paste to wet the array of pads, forming an array of spherical solder interconnects with basically uniform height;

[0015] Step 4: Mill the array of spherical solder interconnects to form array solder bosses on the array pads with consistent height;

[0016] Step 5: Friction butt welding of a single tin-coated solder post:

[0017] The solder post, with its tin-coated end facing downwards and a certain exposed length, is mounted in the jaws of a miniature precision drilling machine. The substrate where the solder pad is located is moved by program control, positioning the solder post and its tin-coated end above the pad and aligning it with the center of the pad. The jaws of the miniature precision drilling machine drive the tin-coated solder post to rotate and press downwards at a speed n1. Once the tin-coated end of the solder post contacts the upper surface of the solder boss, the axial feed of the tin-coated solder post is stopped, but its rotational speed n1 is maintained to preheat the contact surface between the solder boss and the tin-coated solder post. Subsequently, the tin-coated solder post is fed slowly and uniformly axially at a rotational speed n2 and an axial feed speed V. When the predetermined axial pressing amount S1 is reached, the rotation of the tin-coated solder post is stopped, and an axial forging displacement S2 and forging force are applied to the solder boss below. Finally, the tin-coated end... The solder column remains stationary until the brazing boss cools to room temperature. The drill press chuck is then opened and lifted, and the tin-coated solder column and the brazing boss on the pad are connected under the action of frictional heat-forging. The friction butt welding of a single tin-coated solder column is completed. During the friction butt welding of a single tin-coated solder column driven by the precision drill press chuck, the following processes occur: frictional heat generation between the tin coating of the solder column and the brazing boss on the pad; interface temperature rise; softening and deformation of the upper brazing metal on the boss and viscoplastic flow under the action of circumferential friction; adhesion and bonding between the brazing boss and the tin coating of the solder column; atomic diffusion and dynamic recrystallization of the brazing metal and the tin coating of the solder column in the large strain zone near the friction interface, breaking the original interface marks; and the disappearance or reduction of brazing metal vacancies and dislocation defects caused by friction and wear under the action of upsetting force, ultimately forming a reliable connection.

[0018] Step 6: Friction butt welding of arrayed tin-coated solder pillars:

[0019] Repeat step 5 above with the same size and process parameters to achieve friction butt bonding of tin-coated solder pillars on each array of pads.

[0020] Preferably, the welding column in step 1 is any one of a copper column or a brass column with uniform specifications and dimensions prepared according to standards. Preferably, the aspect ratio of the welding column is in the range of 6 to 20, and the diameter d of the welding column is in the range of 0.7 to 1.0 times the diameter D of the welding pad.

[0021] Preferably, the tin-containing coating in step 1 is any one of pure tin coating, SnCu-based solder coating, SnAg-based solder coating, SnAgCu-based solder coating, SnSb-based solder coating, SnBi-based solder coating, and SnPb-based solder coating.

[0022] Preferably, the hot-dip tinning process temperature in step 1 is 250℃~300℃, and the hot-dip tinning time is 20~100 seconds.

[0023] Preferably, the thickness of the tin-containing coating formed at the end of the welding column in step 1 is 5 to 30 micrometers, and the height of the tin-containing coating is 300 to 1000 micrometers.

[0024] Preferably, the thickness of the intermetallic compound layer formed at the interface between the weld post and its tin-containing coating in step 1 ranges from 0.3 to 2.5 micrometers.

[0025] Preferably, the array of pads in step 2 is an array of pads on a chip carrier substrate or an array of pads on a printed circuit board; the friction butt bonding method between materials with significantly different properties is applicable to the connection between the array of pads on the chip carrier substrate and the upper bonding pillar in a primary package; it is also applicable to the connection between the array of pads on the chip carrier substrate and the lower bonding pillar in a secondary package or the connection between the array of pads on the printed circuit board and the upper bonding pillar in a secondary package.

[0026] Preferably, the diameter D of the pads arranged in the array in step 2 is 0.5~2.0 mm.

[0027] Preferably, the solder paste printed on the arrayed pads in step 2 is any one of SnBi-based, SnBiPb-based, SnPb-based, SnZn-based, SnZnBi-based, SnCu-based, SnAg-based, SnAgCu-based, and SnSb-based soft solders.

[0028] Preferably, the heating temperature of the solder paste in step 3 is 20°C to 55°C above the melting point of the solder in the solder paste.

[0029] Preferably, the height h of the array of spherical solder interconnects formed in step 3 is 0.35 to 0.7 times the pad diameter D.

[0030] Preferably, the upper surface diameter D1 of the array solder boss in step 4 is 0.6 to 0.8 times the pad diameter D, and the height h1 of the array solder boss is 0.25 to 0.45 times the pad diameter D.

[0031] Preferably, the exposed end length of the tin-coated weld pillar in the chuck of the micro-precision drill press described in step 5 is 0.5 to 3.0 times the diameter d of the weld pillar, and this parameter remains consistent during the friction welding process of each array of tin-coated weld pillars to ensure that the tin-coated weld pillars have sufficient rigidity and do not become unstable or bend.

[0032] Preferably, the rotational speed n1 of the tin-coated solder post during the preheating of the contact surface between the solder boss and the tin-coated solder post in step 5 is in the range of 10,000 to 35,000 rpm.

[0033] Preferably, in step 5, the rotational speed n2 of the tin-coated solder column during the axial feeding stage after preheating is 8000~14000 rpm, and the axial feed speed V is 20~50 micrometers / second.

[0034] Preferably, the predetermined axial downward pressure S1 of the tin-coated solder post in step 5 is 0.1 to 0.35 times the height h1 of the array solder boss.

[0035] Preferably, the axial upsetting displacement S2 of the tin-coated solder column in step 5 to the lower solder boss is 0.05 to 0.10 times the height h1 of the array solder boss.

[0036] Preferably, when the solder in the solder paste described in step 2 is any one of SnCu-based, SnAg-based, SnAgCu-based, or SnSb-based soft solder, the substrate, the pad to be implanted, and the solder boss on it described in step 5 are placed on a constant temperature heating platform of 50°C to 100°C.

[0037] The present invention has the following beneficial effects:

[0038] First, existing moldless column mounting methods for CGA devices all involve rotating and frictionally embedding the column into the solder balls on the array pads. This is an embedded friction welding method, forming a connection joint where the embedded column is surrounded by solder. In this method, the solder balls, lacking peripheral radial constraint, soften due to frictional heating, resulting in low elastic clamping and adhesion forces on the embedded column, leading to weak column connection strength. The present invention provides a friction butt welding column mounting method between materials with significantly different properties. The diameter of the tin-coated column is similar to the diameter of the pad and its solder bosses, forming a friction butt joint connection. This eliminates the problem of reduced bonding force between the solder balls and column due to softening of the peripheral solder, thus preventing weak column connection strength.

[0039] Secondly, existing moldless solder joint methods for CGA devices are all embedded friction welding methods. Without peripheral radial constraints, the solder softens due to frictional heating, resulting in low elastic clamping and adhesion forces on the embedded solder pillars. This leads to a non-dense viscoplastic solder flow layer near the interface, exhibiting microscopic shrinkage cavities and porosity. Pressure constraints during solder joint placement also have limited effectiveness in controlling the microstructure density of the solder, thus limiting the joint strength. The present invention provides a friction butt welding method for solder joints between materials with significantly different properties. The diameter of the tin-coated solder pillar is similar to the diameter of the pad and the solder boss on it, representing a friction butt joint connection. At the end of welding, a large axial forging force can be applied, resulting in a dense forged structure at the interface and eliminating the problem of low joint strength caused by microscopic shrinkage cavities and porosity.

[0040] Third, existing moldless solder joint methods for CGA devices suffer from low elastic clamping force of the outer solder on the embedded solder pillar, resulting in small strain values ​​in the viscoplastic solder thin layer near the interface, making complete dynamic recrystallization difficult and leading to low joint strength. The present invention provides a friction butt soldering method for solder joints between materials with significantly different properties. The diameter of the tin-coated solder pillar is comparable to the diameter of the pad and the solder boss on it, representing a friction butt connection. At the end of the soldering process, a large axial upsetting force can be applied, resulting in a large strain value in the solder near the interface. The original interface marks are broken by the generated fine recrystallized grains, and the original interface disappears. This eliminates the problem of low joint strength caused by small solder strain values ​​or incomplete recrystallization.

[0041] Fourth, the existing moldless pin-mounting method for CGA devices can produce sharp "flash" notches in the embedded connector form, which can become crack sources during service and easily lead to accelerated thermal fatigue failure of the device. However, the diameter of the tin-coated solder pillar of this invention is similar to the diameter of the pad and the solder boss on it. It belongs to the friction butt connection form and there are no sharp "flash" notches. The thermal fatigue life of the device can be greatly improved during service.

[0042] Fifth, the solder / bond connection of CGA devices involves the connection between materials with vastly different properties. In existing moldless bonding methods for CGA devices, the scallop-shaped interface layer formed by atomic interdiffusion at the solder ball / bond interface is easily worn away by continuous friction. The remaining interface layer after soldering is extremely thin and discontinuous, resulting in low bonding strength. The present invention provides a friction butt bonding method for bonding between materials with vastly different properties. Before bonding, the bonding column is hot-dip tinned, forming a tin-containing coating on the end surface of the bonding column. A scallop-shaped heterogeneous material interface layer is formed between the tin-containing coating and the bonding column. The subsequent bonding is changed to friction welding between the tin-containing coating of the bonding column and the tin-based solder, both homogeneous materials. Furthermore, due to the buffering protection of the tin-containing coating, the scallop-shaped heterogeneous material interface layer is not broken during friction butt bonding. Therefore, the problems of low strength caused by the heterogeneous interface layer being worn away or the remaining interface layer being too thin and discontinuous are not eliminated.

[0043] Sixth, existing moldless pillar-mounting methods for CGA devices all involve rotating and frictionally embedding the pillars into the solder balls on the array pads. This is an embedded friction soldering method. To ensure the embedding depth and pillar rigidity during mounting, the exposed end length of the pillar cannot be too small, and the diameter of the pillar cannot be too small either. This results in a relatively large diameter of the pads and the solder balls on them, affecting the package density. The present invention provides a friction butt soldering pillar-mounting method between materials with significantly different performance characteristics. The diameter of the tin-coated pillar is similar to the diameter of the pads and the solder bosses on them, which can greatly reduce the pad diameter and increase the package density.

[0044] Seventh, the friction butt welding pillar method for materials with significantly different properties of the present invention can save expensive precision mold manufacturing costs compared with the traditional method of mold positioning and reflow soldering used in the field of microelectronic packaging technology; compared with the existing moldless pillar method for CGA devices, the connection strength can be increased by about 45-65% due to the application of forging pressure, and the pillar quality is significantly improved. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the longitudinal section of the interconnection of a single tin-coated solder pillar after friction butt welding in Specific Implementation Method 1.

[0046] Figure 2 This is a schematic diagram of the longitudinal section of the interconnection of a single tin-coated solder column after friction butt welding in Specific Implementation Method 2;

[0047] Figure 3 This is a schematic longitudinal section of the single solder pillar interconnection structure formed after friction butt soldering of the tin-coated copper pillar in the secondary package in Example 1, and after low-temperature reflow soldering of the other end of the tin-coated copper pillar.

[0048] Figure 4 This is a longitudinal section schematic diagram of the single solder pillar interconnection structure formed after friction butt soldering of the primary packaged tin-coated brass pillars in Example 2, and subsequently after low-temperature reflow soldering of the other end of the tin-coated brass pillars. Detailed Implementation Specific implementation method one:

[0050] A method for friction butt welding of inserts between materials with significantly different properties includes the following steps:

[0051] Step 1: Fabrication of the tin coating at the end of the solder column:

[0052] The standard-sized solder column is ultrasonically cleaned in an alcohol solution. Then, the end of the solder column is dipped in solder flux and hot-dip tinning is used to form a tin-containing coating of a certain height at the end of the solder column. The tin-containing coating should be uniform in thickness, bright in surface, and free from balling or wetting. Then, it is ultrasonically cleaned again with an alcohol solution.

[0053] Step 2: Print an appropriate amount of solder paste onto the pads arranged in the printed circuit board array:

[0054] A suitable amount of solder paste is printed on the pads of the printed circuit board array using a mature stencil printing process, requiring that the amount of solder paste printed on the array pads be consistent.

[0055] Step 3: Heat the solder paste to activate the flux and remove the oxide film, melt the solder in the solder paste and wet the array of pads, forming an array of spherical solder interconnects with basically uniform height on the array of pads on the printed circuit board.

[0056] Step 4: Mill the array of spherical solder interconnects to form array solder bosses on the array pads with consistent height;

[0057] Step 5: Friction butt welding of a single tin-coated solder post:

[0058] The solder post, with its tin-coated end facing downwards and a certain exposed length, is mounted in the jaws of a miniature precision drilling machine. The printed circuit board containing the pad to be soldered is moved by program control, positioning the solder post and its tin-coated end above the pad and aligning it with the center of the pad. The jaws of the miniature precision drilling machine rotate the tin-coated solder post downwards at a speed n1. Once the tin-coated end of the solder post contacts the upper surface of the solder boss, the axial feed of the tin-coated solder post is stopped, but its rotational speed n1 is maintained to preheat the contact surface between the solder boss and the tin-coated solder post. Subsequently, the tin-coated solder post is slowly and uniformly fed axially at a speed n2 and an axial feed speed V. When the predetermined axial downward pressure S1 is reached, the rotation of the tin-coated solder post is stopped, and an axial upsetting displacement S2 and upsetting force are applied to the solder boss below. Finally, the tin-coated solder post remains stationary until the solder boss cools to room temperature, then it is opened and lifted. In the drill press chuck, the tin-coated solder column and the solder boss on the pad are connected under the action of frictional heat-forging, and the friction butt welding of a single tin-coated solder column is completed. During the friction butt welding of a single tin-coated solder column driven by the precision drill press chuck, the process involves frictional heat generation between the tin coating of the solder column and the solder boss on the pad, interface temperature rise, softening and deformation of the upper layer of solder on the boss and viscoplastic flow under the action of circumferential friction force, adhesion and bonding between the solder boss and the tin coating of the solder column, atomic diffusion and dynamic recrystallization of the solder and the tin coating of the solder column in the large strain zone near the friction interface, breaking the original interface marks, and the disappearance or reduction of solder vacancies and dislocation defects caused by friction and wear under the action of upsetting force, ultimately forming a reliable connection. The friction butt welding connection of the single tin-coated solder column is the result of the combined action of plastic deformation connection mechanism, diffusion connection mechanism, and recrystallization connection mechanism.

[0059] A schematic diagram of the longitudinal section of the interconnection after friction butt bonding of a single tin-coated solder post is shown below. Figure 1 As shown, A is a cylindrical solder post; B is a tin-containing coating at the end of the cylindrical solder post; C is an intermetallic compound bonding layer formed between the solder post and the tin-containing coating; D is a solder bump after the post is installed; E is a printed circuit board; F is a metal film pad on the printed circuit board; and G is a solder resist film.

[0060] Step 6: Friction butt welding of arrayed tin-coated solder pillars:

[0061] Repeat step 5 above with the same size and process parameters to achieve friction butt bonding of tin-coated solder pillars on each pad arranged in an array on the printed circuit board.

[0062] This invention can be used to achieve high-quality pillar bonding for array bonding of high-frequency, high-power, high-I / O, large-chip CGA devices with high reliability requirements in aerospace, communications, military, and automotive electronics fields. It can also be used for high-quality pillar bonding of array bonding of planar array packaged devices with long lifespan requirements in civilian applications, as well as for bonding between rod-shaped and plate-shaped parts with significantly different material properties. Specific Implementation Method Two:

[0064] A method for friction butt welding of inserts between materials with significantly different properties includes the following steps:

[0065] Step 1: Fabrication of the tin coating at the end of the solder column:

[0066] The standard-sized solder column is ultrasonically cleaned in an alcohol solution. Then, the end of the solder column is dipped in solder flux and hot-dip tinning is used to form a tin-containing coating of a certain height at the end of the solder column. The tin-containing coating should be uniform in thickness, bright in surface, and free from balling or wetting. Then, it is ultrasonically cleaned again with an alcohol solution.

[0067] Step 2: Print an appropriate amount of solder paste onto the pads arranged in the chip carrier substrate array:

[0068] A suitable amount of solder paste is printed on the pads of the chip carrier substrate array using a mature stencil printing process, requiring that the amount of solder paste printed on the array pads be consistent.

[0069] Step 3: Heat the solder paste to activate the flux and remove the oxide film, melt the solder in the solder paste and wet the array of pads, forming an array of spherical solder interconnects with basically uniform height on the pads of the chip carrier substrate array.

[0070] Step 4: Mill the array of spherical solder interconnects to form array solder bosses on the array pads with consistent height;

[0071] Step 5: Friction butt welding of a single tin-coated solder post:

[0072] The solder post, with its tin-coated end facing downwards and a certain exposed length, is mounted in the jaws of a micro-precision drilling machine. The chip carrier substrate containing the solder pad is moved by program control, positioning the solder post and its tin-coated end above the solder pad and aligning it with the center of the pad. The jaws of the micro-precision drilling machine rotate the tin-coated solder post downwards at a speed n1. Once the tin-coated end of the solder post contacts the upper surface of the solder bump, the axial feed of the tin-coated solder post is stopped, but its rotational speed n1 is maintained to preheat the contact surface between the solder bump and the tin-coated solder post. Subsequently, the tin-coated solder post is slowly and uniformly fed axially at a speed n2 and an axial feed speed V. When the predetermined axial pressing amount S1 is reached, the rotation of the tin-coated solder post is stopped, and an axial forging displacement S2 and forging force are applied to the solder bump below. Finally, the tin-coated solder post remains stationary until the solder bump cools to room temperature, then it is opened and lifted. The friction butt welding of a single tin-coated solder column is completed when the drill press chuck moves the tin-coated solder column to the solder pad under frictional heat-forging action. During the friction butt welding of the single tin-coated solder column, the process involves frictional heat generation between the tin coating of the solder column and the solder pad, an increase in interface temperature, softening and deformation of the upper layer of solder on the pad and viscoplastic flow under circumferential friction, adhesion and bonding between the solder pad and the tin coating of the solder column, atomic diffusion and dynamic recrystallization of the solder and the tin coating of the solder column in the large strain zone near the friction interface, breaking the original interface marks, and the disappearance or reduction of solder vacancies and dislocation defects caused by friction and wear under the action of upsetting force, ultimately forming a reliable connection. The friction butt welding connection of the single tin-coated solder column is the result of the combined action of plastic deformation connection mechanism, diffusion connection mechanism, and recrystallization connection mechanism.

[0073] A schematic diagram of the longitudinal section of the interconnection after friction butt bonding of a single tin-coated solder post is shown below. Figure 2 As shown, A is a cylindrical solder post; B is a tin-containing coating at the end of the cylindrical solder post; C is an intermetallic compound layer formed between the solder post and the tin-containing coating; D is a solder bump after the post is installed; E1 is the chip carrier substrate; F is a metal film pad on the chip carrier substrate; and G is a solder resist film.

[0074] Step 6: Friction butt welding of arrayed tin-coated solder pillars:

[0075] Repeat step 5 above with the same size and process parameters to achieve friction butt bonding of tin-coated solder pillars on each pad arranged in the array on the chip carrier substrate.

[0076] This invention can be used to achieve high-quality pillar connection of array bonding pillars for high-frequency, high-power, high-I / O, large-chip CGA devices with high reliability requirements in aerospace, communications, military, automotive electronics and other fields. It can also be used for high-quality pillar connection of array bonding pillars for civilian long-life planar packaged devices, as well as connection between rod-shaped parts and plate-shaped parts with significantly different material properties. Specific implementation method three:

[0078] The welding column mentioned in step 1 of this embodiment is any one of a copper column or a brass column with uniform specifications and dimensions prepared according to standards, and the length-to-diameter ratio of the welding column is in the range of 6 to 20, and the diameter d of the welding column is in the range of 0.7 to 1.0 times the diameter D of the welding pad.

[0079] The other steps and parameters are the same as in specific implementation method one or two. Specific implementation method four:

[0081] The tin-containing coating mentioned in step 1 of this embodiment is any one of pure tin coating, SnCu-based solder coating, SnAg-based solder coating, SnAgCu-based solder coating, SnSb-based solder coating, SnBi-based solder coating, and SnPb-based solder coating. The hot-dip tinning process temperature in step 1 is 250℃~300℃, and the hot-dip tinning time is 20~100 seconds.

[0082] The other steps and parameters are the same as in any of the specific implementation methods one to three. Specific implementation method five:

[0084] In this embodiment, the thickness of the tin-containing coating formed at the end of the weld pillar in step 1 is 5 to 30 micrometers, the height of the tin-containing coating is 300 to 1000 micrometers, and the thickness of the intermetallic compound layer formed at the weld pillar / tin-containing coating interface in step 1 is 0.3 to 2.5 micrometers.

[0085] The other steps and parameters are the same as in any of the specific implementation methods one to four. Specific implementation method six:

[0087] In this embodiment, the diameter D of the array of pads in step 2 is 0.5~2.0 mm, and the solder paste printed on the array of pads in step 2 is any one of SnBi-based, SnBiPb-based, SnPb-based, SnZn-based, SnZnBi-based, SnCu-based, SnAg-based, SnAgCu-based, and SnSb-based soft solders.

[0088] The other steps and parameters are the same as in any one of the specific implementation methods one to five. Specific implementation method seven:

[0090] In this embodiment, the heating temperature of the solder paste in step 3 is 20°C to 55°C above the melting point of the solder in the solder paste, and the height h of the array of spherical solder interconnects in step 3 is 0.35 to 0.7 times the diameter D of the solder pad.

[0091] The other steps and parameters are the same as those in any of the specific implementation methods one through six. Detailed implementation method eight:

[0093] In this embodiment, the upper surface diameter D1 of the array solder boss described in step 4 is 0.6 to 0.8 times the pad diameter D, and the height h1 of the array solder boss is 0.25 to 0.45 times the pad diameter D.

[0094] The other steps and parameters are the same as in any of the specific implementation methods one through seven. Specific implementation method nine:

[0096] In step 5 of this embodiment, the exposed end length of the weld post, which is mounted in the jaws of the micro-precision drilling machine, is 0.5 to 3.0 times the diameter d of the weld post. This parameter remains consistent during the friction welding process of each tin-coated weld post to ensure that the tin-coated weld post has sufficient rigidity and does not become unstable or bend.

[0097] The other steps and parameters are the same as those in any of the specific implementation methods one through eight. Specific Implementation Method Ten:

[0099] In this embodiment, when the solder paste described in step 2 is any one of SnCu-based, SnAg-based, SnAgCu-based, or SnSb-based soft solder, the substrate, the pad to be implanted, and the solder bosses on it described in step 5 are placed on a constant temperature heating platform and preheated to 50°C~100°C.

[0100] The other steps and parameters are the same as those in any of the specific implementation methods one through nine. Detailed Implementation Method Eleven:

[0102] In step 5 of this embodiment, the rotational speed n1 of the tin-coated solder column during the preheating of the contact surface between the solder boss and the tin-coated solder column is 10,000 to 35,000 rpm, and the rotational speed n2 of the tin-coated solder column during the axial feed stage after preheating is 8,000 to 14,000 rpm, and the axial feed speed V is 20 to 50 micrometers per second.

[0103] The other steps and parameters are the same as those in Specific Implementation Methods One through Ten. Detailed Implementation Method Twelve:

[0105] In this embodiment, the predetermined axial downward pressure S1 of the tin-coated solder column in step 5 is 0.1 to 0.35 times the height h1 of the array solder boss, and the axial upsetting displacement S2 of the tin-coated solder column to the lower solder boss is 0.05 to 0.10 times the height h1 of the array solder boss.

[0106] The other steps and parameters are the same as those in any of the specific implementation methods one through eleven.

[0107] Example

[0108] Example 1:

[0109] Figure 3 This is a schematic diagram of an interconnect structure in the secondary package array solder pad interconnect structure of a CGA device, where both ends of a single tin-coated solder pad are connected. In this diagram, 1 represents a cylindrical copper pillar; 2 represents the tin-coated coating at the end of the cylindrical copper pillar; 3 represents the intermetallic compound layer formed between the copper pillar and the tin-coated coating; 4 represents the solder bump connected to one end of the copper pillar after soldering; 5 represents the solder fillet formed after low-temperature reflow soldering at the other end of the copper pillar after soldering; for friction butt soldering of array solder pads in the secondary package, 6 represents the chip carrier substrate; 7 represents the printed circuit board; 8 represents the metal film pad on the chip carrier substrate or printed circuit board; 9 represents the solder resist on the chip carrier substrate or printed circuit board; and 10 represents the intermetallic compound layer formed between the copper pillar and solder after low-temperature reflow soldering at the other end of the copper pillar after soldering.

[0110] Taking the friction butt bonding and connection of array pillars in secondary packaging as an example, the process of CGA device array pillar interconnection structure mainly includes the initial friction butt bonding connection process of array pillars on the pads arranged in the array on the printed circuit board, and the subsequent reflow soldering process of the other end of the array pillars to the pads arranged in the array on the chip carrier substrate and the low melting point solder paste on them.

[0111] Regarding the initial friction butt welding post connection process, the present invention provides a friction butt welding post connection method between materials with significantly different properties, comprising the following steps:

[0112] Step 1: Fabrication of the tin coating at the end of the solder column:

[0113] According to design standards, cylindrical copper pillars with a length-to-diameter ratio of 12 and a diameter d of 0.8D, matching the diameter D of the pads arrayed on the printed circuit board, are prepared. After ultrasonic cleaning in an alcohol solution, the ends of the copper pillars are dipped in solder flux and then hot-dipped in pure tin solution at 270°C for 80 seconds to form a tin-containing coating with a height of approximately 900 micrometers and a thickness of approximately 15-20 micrometers. An intermetallic compound layer with a thickness of approximately 0.8-1.8 micrometers is formed at the interface between the copper pillar and the pure tin coating. After removal, the pure tin coating is inspected to ensure that the thickness is uniform, the surface is bright, and there are no balling or wetting phenomena. Then, ultrasonic cleaning is performed again in an alcohol solution.

[0114] Step 2: Using a mature stencil printing process, print an equal and appropriate amount of Sn8Zn3Bi lead-free solder paste onto the array of pads with a diameter D of 1.50 mm on the printed circuit board. The amount of solder paste printed should be such that the height h of the array of spherical solder interconnects formed after reflow is 0.40 to 0.60 times the diameter D of the pad.

[0115] Step 3: Heat the solder paste according to the reflow heating curve of Sn8Zn3Bi lead-free solder paste. The peak reflow temperature is controlled at 220~240℃. The flux in Sn8Zn3Bi solder paste is first activated and the oxide film is removed. Then the solder in the solder paste melts and wets the array of pads, forming an array of spherical solder interconnects with basically consistent height on the array of pads on the printed circuit board.

[0116] Step 4: Mill the array of spherical solder interconnects on the array pads to form array solder bosses with an upper surface diameter D1 that is 0.6 to 0.7 times the pad diameter D, a height h1 that is 0.35 to 0.45 times the pad diameter D, and a consistent height.

[0117] Step 5: Friction butt welding of individual tin-coated solder pillars:

[0118] A copper pillar with its tin-coated end facing downwards is mounted in the jaws of a miniature precision drill press, ensuring the exposed end length is approximately 1.5 times the pillar's diameter (d). The printed circuit board containing the pad to be soldered is moved via a program to position the copper pillar and its tin-coated end above the pad and aligned with its center. The miniature precision drill press jaws rotate the tin-coated copper pillar downwards at a speed of 15,000 rpm (n1). Once the tin-coated end of the copper pillar contacts the upper surface of the solder boss, the axial feed of the tin-coated copper pillar is stopped, but the rotational speed of 15,000 rpm (n1) is maintained to preheat the contact between the solder boss and the tin-coated copper pillar. The tin-coated copper column is then fed slowly and uniformly at a rotational speed n2 of 10,000 rpm and an axial feed speed V of 25 μm / s. When the axial downward pressure S1 reaches 0.15 times the height h1 of the array solder boss, the rotation of the tin-coated copper column is stopped, and an axial upsetting displacement S2 and upsetting force of 0.05 times the height h1 of the array solder boss are applied to the lower solder boss. Finally, the tin-coated copper column remains stationary until the solder boss cools to room temperature. The drill chuck is then opened and lifted, and the tin-coated copper column and the solder boss on the pad are connected under frictional heat-forging action. The friction butt welding of a single tin-coated copper column is completed. Because the frictional bonding between the tin-coated copper pillar and the solder boss on the pad involves frictional heat generation, interface temperature rise, softening and deformation of the upper solder on the boss under circumferential frictional force and viscoplastic flow, adhesion and bonding between the solder boss and the tin-coated copper pillar, atomic diffusion and dynamic recrystallization of the solder and the tin-coated copper pillar in the large strain zone near the friction interface, recrystallization breaking the original interface marks, and the disappearance or reduction of solder vacancies and dislocation defects caused by frictional wear under the action of upsetting force, ultimately forming a reliable connection; therefore, the frictional bonding of a single tin-coated copper pillar is the result of the combined effects of plastic deformation connection mechanism, diffusion connection mechanism, and recrystallization connection mechanism.

[0119] Step Six: Friction Butt Welding of Arrayed Tin-Coated Solder Posts:

[0120] Repeat step five above with the same size and process parameters to achieve friction butt bonding of tin-coated copper pillars on each pad arranged in an array on the printed circuit board.

[0121] First, friction butt soldering pillars are installed on pads arranged in an array on the printed circuit board. Then, low-melting-point solder paste is printed on pads arranged in an array on the chip carrier substrate (the melting point of the solder in the solder paste should be at least 35°C lower than the melting point of the solder bumps at the friction butt soldering pillar ends). The other end of the array of tin-coated copper pillars is heated to complete the low-temperature reflow soldering process between the array of pads on the chip carrier substrate (the peak temperature is controlled within 20~30°C above the melting point of the solder in the low-melting-point solder paste). During this period, the connection part of the aforementioned friction butt soldering pillars is also in the same low-temperature reflow soldering heating environment. The interdiffusion of atoms at the interface of the tin-coated copper pillars / solder bumps in the high-temperature solid state can further improve the connection strength at the end of the friction butt soldering pillars, thereby realizing the connection between the two ends of the array of tin-coated copper pillars. This has no mechanical impact on the chip and the chip carrier substrate, and has a protective effect on the chip. Alternatively, the steps described in this embodiment can be used to first perform friction butt bonding of pillars on the chip carrier substrate, and then complete the low-temperature reflow soldering process between the other end of the array of tin-coated copper pillars and the pads arranged in an array on the printed circuit board.

[0122] Example 2:

[0123] In addition to being used for bonding between secondary packaged chip carrier substrates and printed circuit boards, the CGA device array pillar interconnect structure can also be used for bonding between primary packaged chips and chip carrier substrates. Figure 4 This is a schematic diagram of an interconnect structure in the primary package array solder pad interconnect structure of a CGA device, where both ends of a single tin-coated solder pad are connected. In this diagram, 11 is a cylindrical brass pillar, 2 is the tin-coated coating at the end of the cylindrical brass pillar, 3 is the intermetallic compound layer formed between the cylindrical brass pillar and the tin-coated coating, 41 is the solder bump connected to one end of the tin-coated brass pillar after the pillar is installed, and 51 is the solder fillet formed after low-temperature reflow soldering at the other end of the tin-coated brass pillar after the pillar is installed. For the friction butt soldering of the array solder pads in the primary package, 61 is the chip, 71 is the chip carrier substrate, 81 is the metal film pad on the chip or chip carrier substrate, 91 is the solder resist on the chip or chip carrier substrate, and 101 is the intermetallic compound layer formed between the brass pillar and solder after low-temperature reflow soldering at the other end of the tin-coated brass pillar after the pillar is installed.

[0124] Taking the friction butt bonding and connection of array pillars in a primary package as an example, the process of CGA device array pillar interconnection structure mainly includes the initial friction butt bonding connection process of array pillars on the array pads of the chip carrier substrate, and the subsequent reflow soldering process between the other end of the array pillar and the pads on the front of the chip and the low melting point solder paste thereon.

[0125] Regarding the initial friction butt welding post connection process, the present invention provides a friction butt welding post connection method between materials with significantly different properties, comprising the following steps:

[0126] Step 1: Fabrication of the tin coating at the end of the solder column:

[0127] According to design standards, cylindrical brass pillars with a length-to-diameter ratio of 10 and a diameter d0 of 1.0 D0, matching the diameter D0 of the pads arrayed on the chip carrier substrate, are fabricated. After ultrasonic cleaning in an alcohol solution, the ends of the cylindrical brass pillars are dipped in solder flux and then hot-dipped in a Sn0.7Cu solder solution at 290℃ for 60 seconds to form a Sn0.7Cu solder coating with a height of approximately 500 micrometers and a thickness of approximately 10-15 micrometers. An intermetallic compound layer with a thickness of approximately 1.0-2.0 micrometers is formed at the interface between the brass pillar and the Sn0.7Cu solder coating. After removal, the Sn0.7Cu solder coating is inspected to ensure that the thickness is uniform, the surface is bright, and there are no balling or wetting phenomena. Then, ultrasonic cleaning is performed again in an alcohol solution.

[0128] Step 2: On the chip carrier substrate, an equal and appropriate amount of Sn3.0Ag0.5Cu lead-free solder paste is printed on the array of pads with a diameter D0 of 0.80 mm using a mature stencil printing process. The amount of solder paste printed should be such that the height h0 of the array of spherical solder interconnects formed after reflow is 0.45 to 0.65 times the diameter D0 of the pad.

[0129] Step 3: Heat the solder paste according to the reflow soldering heating curve of Sn3.0Ag0.5Cu lead-free solder paste, and control the peak reflow soldering temperature at 245~265℃. The flux in Sn3.0Ag0.5Cu solder paste is first activated and the oxide film is removed. Then the solder in the solder paste melts and wets the array of pads, forming an array of spherical solder interconnects with basically consistent height on the pads of the chip carrier substrate array.

[0130] Step 4: Mill the array of spherical solder interconnects on the array pads to form an upper surface diameter D. 01 It is 0.7 to 0.8 times the pad diameter D0, and the height h 01 An array of solder bosses with a height consistent to 0.25 to 0.35 times the diameter D0 of the solder pad;

[0131] Step 5: Friction butt welding of individual tin-coated solder pillars:

[0132] The brass pillar with the Sn0.7Cu solder coating is mounted downwards in the jaws of a miniature precision drilling machine. The exposed length of the Sn0.7Cu solder-coated brass pillar is controlled to be approximately 2.5 times the diameter d0 of the brass pillar. The chip carrier substrate, the pad to be implanted, and the solder bumps on it are placed on a constant-temperature heating platform and preheated to 50℃~100℃. The chip carrier substrate where the pad to be implanted is located is moved by program control, so that the brass pillar and its tin-coated end are positioned above the pad to be implanted and aligned with the center of the pad. The jaws of the miniature precision drilling machine drive the Sn0.7Cu solder-coated brass pillar to rotate at a speed n of 20,000 rpm. 01 Rotate downwards until the end of the brass post with the Sn0.7Cu solder coating contacts the upper surface of the solder boss. Then, stop the axial feed of the brass post with the Sn0.7Cu solder coating but maintain a rotational speed of 20,000 rpm. 01 To preheat the contact surface of the solder boss / Sn0.7Cu solder-coated brass pillar; then rotate the Sn0.7Cu solder-coated brass pillar at a speed of 15,000 rpm. 02 A uniform and slow axial feed rate V0 of 35 micrometers / second is applied, while the axial downward pressure S... 01 Reaching the height h of the array solder boss 01 After 0.3 times, stop rotating the brass pillar containing Sn0.7Cu solder coating and give the lower solder boss a height h of 0.08 times the array solder boss height. 01 The axial upsetting displacement S2 and upsetting force; finally, the brass column with Sn0.7Cu solder coating remains stationary until the solder boss cools to room temperature, the drill chuck is opened and lifted, and the brass column with Sn0.7Cu solder coating forms a connection with the solder boss on the pad under the action of frictional heat-forging, and the friction butt welding of a single tin-coated solder column is completed. The friction butt welding connection of a single brass pillar with a Sn0.7Cu solder coating involves a series of processes, including frictional heat generation between the brass pillar containing Sn0.7Cu solder coating and the solder boss on the pad, increased interface temperature, softening and deformation of the upper layer of solder on the boss, viscoplastic flow under circumferential friction, adhesion and bonding between the solder boss and the brass pillar containing Sn0.7Cu solder coating, atomic diffusion and dynamic recrystallization of the solder and the brass pillar containing Sn0.7Cu solder coating in the large strain zone near the friction interface, recrystallization breaking the original interface marks, and the disappearance or reduction of solder vacancies and dislocation defects caused by friction and wear under the action of upsetting force, ultimately forming a reliable connection. Therefore, the friction butt welding connection of a single brass pillar with a Sn0.7Cu solder coating is the result of the combined effects of plastic deformation connection mechanism, diffusion connection mechanism, and recrystallization connection mechanism.

[0133] Step Six: Friction Butt Welding of Arrayed Tin-Coated Solder Posts:

[0134] Repeat step five above with the same size and process parameters to achieve friction butt bonding of brass pillars with Sn0.7Cu solder coating on each pad arranged in the array on the chip carrier substrate.

[0135] First, friction butt soldering pillars are installed on the pads arranged in the chip carrier substrate array. Then, low-melting-point solder paste is printed on the metal film pads arranged in the array on the front side of the chip (the melting point of the solder in the solder paste should be at least 35°C lower than the melting point of the solder bumps at the friction butt soldering pillar ends). The other end of the array of brass pillars with Sn0.7Cu solder coating is heated to complete the low-temperature reflow soldering process between the array of pads on the chip (the peak temperature is controlled within the range of 20~30°C above the melting point of the solder in the low-melting-point solder paste). During this period, the connection part of the aforementioned friction butt soldering pillars is also in the same low-temperature reflow soldering heating environment. The interdiffusion of atoms at the interface of the brass pillars / solder bumps with Sn0.7Cu solder coating in the high-temperature solid phase state can further improve the connection strength at the end of the friction butt soldering pillars, thereby realizing the connection between the two ends of the array of brass pillars with Sn0.7Cu solder coating. This has no mechanical impact on the chip and has a protective effect on the chip.

Claims

1. A method for friction butt welding of inserts between materials with significantly different properties, characterized in that, Includes the following steps: Step 1: Fabrication of the tin coating at the end of the solder column: Standard-sized solder pillars are ultrasonically cleaned in an alcohol solution, then the ends of the solder pillars are dipped in flux, and then a tin-containing coating of a certain height is formed at the ends of the solder pillars using a hot-dip tinning method. Finally, they are ultrasonically cleaned again with an alcohol solution. The welding column mentioned in step 1 is any one of copper or brass columns with uniform specifications and dimensions prepared according to standards. The aspect ratio of the welding column is in the range of 6 to 20, and the diameter d of the welding column is in the range of 0.7 to 1.0 times the diameter D of the welding pad. Step 2: Print an appropriate amount of solder paste onto the array of pads. The diameter D of the array of pads is 0.5 to 2.0 mm. Step 3: Heat the solder paste to wet the array of pads, forming an array of spherical solder interconnects with basically uniform height; The heating temperature of the solder paste in step 3 is 20°C to 55°C above the melting point of the solder in the solder paste, and the height h of the array of spherical solder interconnects is 0.35 to 0.7 times the diameter D of the solder pad. Step 4: Mill the array of spherical solder interconnects to form array solder bosses on the array pads with consistent height; The upper surface diameter D1 of the array solder boss described in step 4 is 0.6 to 0.8 times the pad diameter D, and the height h1 of the array solder boss is 0.25 to 0.45 times the pad diameter D. Step 5: Friction butt welding of a single tin-coated solder post: The solder post, with its tin-coated end facing downwards and a certain exposed length, is mounted in the jaws of a miniature precision drilling machine. The substrate where the solder pad is located is moved by program control, positioning the solder post and its tin-coated end above the pad and aligning it with the center of the pad. The jaws of the miniature precision drilling machine drive the tin-coated solder post to rotate and press downwards at a speed n1. Once the tin-coated end of the solder post contacts the upper surface of the solder boss, the axial feed of the tin-coated solder post is stopped, but its rotational speed n1 is maintained to preheat the contact surface between the solder boss and the tin-coated solder post. Subsequently, the tin-coated solder post is fed slowly and uniformly axially at a rotational speed n2 and an axial feed speed V. When the predetermined axial pressing amount S1 is reached, the rotation of the tin-coated solder post is stopped, and an axial upsetting displacement S2 and upsetting force are applied to the solder boss below. Finally, the tin-coated solder post remains stationary until the solder boss cools to room temperature. The drilling machine jaws are then opened and lifted, and the tin-coated solder post and the solder pad are aligned. Under the action of frictional heat-forging, the brazing bosses form a connection, and the friction butt welding of a single tin-coated brazing post is completed. During the friction butt welding of a single tin-coated brazing post driven by the chuck of the precision drilling machine, the following processes occur: frictional heat generation between the tin coating of the brazing post and the brazing boss on the pad; interface temperature rise; softening and deformation of the upper brazing metal on the boss and viscoplastic flow under the action of circumferential friction force; adhesion and bonding between the brazing boss and the tin coating of the brazing post; atomic diffusion and dynamic recrystallization of the brazing metal and the tin coating of the brazing post in the large strain zone near the friction interface, breaking the original interface traces. The brazing vacancies and dislocation defects caused by friction and wear, as well as the shrinkage defects caused by the low elastic clamping force of the thermally softened brazing metal without peripheral radial constraint on the embedded brazing post, disappear or decrease under the action of upsetting force and finally form a reliable connection. Since the upper surface diameter D1 of the brazing boss is close to the diameter d of the brazing post, no flash defects are generated in the weld joint during the friction butt welding of the post. The exposed end length of the tin-coated solder column in the chuck of the micro-precision drilling machine described in step 5 is 0.5 to 3.0 times the diameter d of the solder column, and this parameter remains consistent during the friction butt welding process of each array of tin-coated solder columns; the rotational speed n1 of the tin-coated solder column is 10,000 to 35,000 rpm when the contact surface of the solder boss / tin-coated solder column is preheated, and the rotational speed n2 of the tin-coated solder column during the axial feed stage after preheating is 8,000 to 14,000 rpm, and the axial feed speed V is 20 to 50 micrometers / second; The predetermined axial downward pressure S1 of the tin-coated solder column in step 5 is 0.1 to 0.35 times the height h1 of the array solder boss, and the axial upsetting displacement S2 of the tin-coated solder column to the lower solder boss is 0.05 to 0.10 times the height h1 of the array solder boss. Step 6: Friction butt welding of arrayed tin-coated solder pillars: Repeat step 5 above with the same size and process parameters to achieve friction butt bonding of tin-coated solder pillars on each array of pads.

2. The method for friction butt welding of a column between materials with significantly different properties according to claim 1, characterized in that, The hot-dip tinning process in step 1 is carried out at a temperature of 250°C to 300°C for 20 to 100 seconds. The thickness of the tin-containing coating formed at the end of the solder post is 5 to 30 micrometers, and the height of the tin-containing coating is 300 to 1000 micrometers. The type of tin-containing coating is any one of pure tin coating, SnCu-based solder coating, SnAg-based solder coating, SnAgCu-based solder coating, SnSb-based solder coating, SnBi-based solder coating, and SnPb-based solder coating. The thickness of the intermetallic compound layer formed at the interface between the solder post and the tin-containing coating is in the range of 0.3 to 2.5 micrometers.

3. The method for friction butt welding of a column between materials with significantly different properties according to claim 2, characterized in that, The array of pads mentioned in step 2 are pads arrayed on the chip carrier substrate or pads arrayed on the printed circuit board; the friction butt bonding pillar method between materials with significantly different performance is applicable to the connection between the pads arrayed on the chip carrier substrate and the upper bonding pillar in a primary package. It is also applicable to the connection between the pads arranged in an array on the chip carrier substrate and the lower solder pillar in secondary packaging, or the connection between the pads arranged in an array on the printed circuit board and the upper solder pillar in secondary packaging.

4. The method for friction butt welding of a column between materials with significantly different properties according to claim 3, characterized in that, The solder paste printed on the array of pads in step 2 is any one of the following: SnBi-based, SnBiPb-based, SnPb-based, SnZn-based, SnZnBi-based, SnCu-based, SnAg-based, SnAgCu-based, and SnSb-based soft solder.

5. The method for friction butt welding of a column between materials with significantly different properties according to claim 1, characterized in that, When the solder paste described in step 2 is any one of SnCu-based, SnAg-based, SnAgCu-based, or SnSb-based soft solder, the substrate, the pads to be implanted, and the solder bosses on them described in step 5 are placed on a constant temperature heating platform and preheated to 50°C to 100°C.

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