Near-spherical particle brazing filler metal and processing method and device thereof

Abstract

The invention relates to the technical field of brazing material processing, in particular to nearly-spherical particle brazing filler metal and a processing method and device thereof. The processing method of the nearly spherical particle brazing filler metal comprises the following steps: pre-cutting a brazing filler metal wire into a shape similar to a bean pod, coating a laser absorption coating at a notch connecting part formed by pre-cutting, and fusing the notch connecting part by adopting laser, so as to obtain the nearly spherical particle brazing filler metal. According to the method, mechanical pre-cutting is adopted, meanwhile, the high-energy absorption graphite coating is coated at the notch connecting position, the laser generator is additionally arranged at the rear end to melt the filaments to form the nearly-spherical brazing filler metal, the number of used equipment is small, energy consumption is low, efficiency is high, the material utilization rate is high, loss is basically avoided, the size of the nearly-spherical brazing filler metal is easy to control, and uniformity is good.

Description

Technical Field

[0001] The invention relates to the technical field of brazing material processing, and in particular to a nearly spherical particle brazing material and a processing method and device thereof. Background Art

[0002] Brazing is a method of welding, in which the brazing filler metal is placed on the base material to be welded, and the brazing filler metal is melted by heating while the base material does not melt, thus forming a chemical metallurgical bond at the interface to be welded. Brazing plays an irreplaceable role in complex structural connections and precision connections. Brazing fillers are usually in the form of filaments, sheets, strips, and powders. With the development of technology, more and more complex structural parts are appearing, and the form of brazing fillers is also required to be more diversified. Spherical brazing fillers have the characteristic of precise weight, and are important in the spot welding and fixation of some complex components. The usage scenario is to suck up the brazing filler metal ball through a pneumatic welding gun, and fix the parts to be welded by resistance welding. At this time, the brazing filler metal ball is not completely melted, and the brazing filler metal ball is subsequently completely melted by heating to achieve precision welding of complex components.

[0003] In the prior art, solder balls are generally prepared by cutting wires into particles, which are then ground into spherical particles. The grinding process results in a large loss of material, and the solder usually contains precious metals or rare metals, so the material cost and processing cost are high, and grinding causes a huge waste of material.

[0004] Laser cutting is an effective processing method, but the laser absorption rate of different materials varies greatly, especially silver alloys and copper alloys have high laser reflectivity. The laser power required to form molten droplets into balls is very high, which increases the cost of equipment, reduces efficiency, and makes it difficult to control the size of the molten droplets.

[0005] Therefore, it is of great significance to provide a method and device for processing near-spherical solder particles with low material loss, low energy consumption and controllable size.

[0006] In view of this, the present invention is proposed. Summary of the invention

[0007] The first purpose of the present invention is to provide a method for processing near-spherical solder particles to solve the technical problems of large material loss, high energy consumption and difficult control of the size of spherical solder in existing methods of processing near-spherical solder. The method of the present invention uses less equipment, has low energy consumption, high efficiency, and high material utilization rate, and the size of the near-spherical solder is easy to control and has good uniformity.

[0008] The second object of the present invention is to provide a nearly spherical particle solder, which is prepared by the processing method of the nearly spherical particle solder as described above.

[0009] The third object of the present invention is to provide a processing device for nearly spherical solder particles, which is suitable for the processing method for nearly spherical solder particles as described above.

[0010] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0011] A method for processing nearly spherical solder particles comprises the following steps:

[0012] The solder wire is pre-cut into a pod shape, and a laser absorbing coating is coated on the incision connection formed by the pre-cutting, and then the incision connection is melted by laser to obtain the nearly spherical particle solder.

[0013] Preferably, the solder wire includes any one of copper alloy wire, silver alloy wire, nickel alloy wire and iron alloy wire.

[0014] Preferably, the wire diameter of the solder wire and the length of a single pre-cut section both match the diameter of the nearly spherical solder particles.

[0015] Preferably, the diameter of the incision connection is 0.2 mm-d / 2, wherein d is the wire diameter of the solder wire.

[0016] Preferably, the laser absorbing coating comprises the following components by mass percentage:

[0017] Graphite powder 40%-70%, high molecular organic material 4%-8%, thickener 2%-5% and solvent 20%-52%.

[0018] Preferably, the particle size of the graphite powder is less than 10 μm.

[0019] Preferably, the polymer organic material includes at least one of polyacrylate, polyvinyl butyral, and polyvinyl pyrrolidone.

[0020] Preferably, the thickener comprises methyl cellulose and / or ethyl cellulose.

[0021] Preferably, the solvent includes at least one of trichloroethylene, dichloroethylene, carbon tetrachloride, toluene, p-xylene, ethyl acetate, dimethyl sulfoxide, butyl acetate, methanol, ethanol, chloroform and acetone.

[0022] Preferably, the power of the laser is 500-5000W.

[0023] A nearly spherical particle solder is prepared by using the processing method of the nearly spherical particle solder described in any one of the aforementioned embodiments.

[0024] A processing device for nearly spherical solder particles, applicable to the processing method for nearly spherical solder particles described in any one of the aforementioned embodiments, comprising:

[0025] Two disc horseshoe cutters symmetrically arranged about the solder wire and with adjustable gaps are used to pre-cut the solder wire passing through the gaps therebetween, the disc horseshoe cutters comprising a disc and a plurality of horseshoe cutters fixed on the disc, the plurality of horseshoe cutters being evenly distributed around the circumference of the disc;

[0026] a laser absorbing paint feeding device, used for providing the laser absorbing paint to the horseshoe-shaped cutter;

[0027] A laser generator, the laser generator is located downstream of the disc horseshoe hob and is used to fuse the pre-cut portion of the solder wire;

[0028] The material collecting bin is used to collect nearly spherical solder particles.

[0029] Preferably, the laser absorbing paint feeding device includes a paint box and laser absorbing paint located in the paint box, the side wall of the paint box close to one end of the disc horseshoe-shaped roller is a flexible porous material, the horseshoe-shaped cutter passes through the paint box during rotation, contacts the flexible porous material and dips the laser absorbing paint, and applies the laser absorbing paint to the cut connection of the solder wire when pre-cutting the solder wire.

[0030] Preferably, the flexible porous material includes any one of sponge, cotton and absorbent paper.

[0031] Preferably, the viscosity of the laser absorbing coating is 2000-5000 cP.

[0032] Preferably, the material of the horseshoe-shaped cutter includes any one of cemented carbide, high-speed steel and superhard material.

[0033] Preferably, the gap a between the two disks satisfies the following conditions: a≥d, 0.2mm≤a-2h<d / 2, wherein d is the wire diameter of the solder wire, and h is the height of the blade of the horseshoe cutter.

[0034] Preferably, the rotational linear velocity V1 of the disc horseshoe cutter and the wire feeding speed V2 of the solder wire satisfy: V2=lNV1 / [π(D+2h)], wherein l is the length of a single pre-cut segment, N is the number of the horseshoe cutters on a single disc, D is the diameter of the disc, and h is the height of the blade head of the horseshoe cutter.

[0035] Preferably, the laser generator is a YAG laser generator or a semiconductor laser generator.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] The method of the present invention first pre-cuts the wire into a shape similar to a bean pod, and coats a laser absorbing coating at the diameter change portion to form a high-energy absorption zone at the incision connection portion, and then melts the diameter change portion through laser cutting to form a nearly spherical solder. The method of the present invention does not require equipment such as a cutting machine, a ball rolling machine, and a ball grinding machine, and requires less equipment, has low cost, and high efficiency; and has a high material utilization rate and basically no loss; the required laser power is low, and compared with simple laser melting droplet balling, the energy consumption is significantly reduced, and the size of the prepared nearly spherical solder is controllable and has good uniformity. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0039] Figure 1 A flow chart of the preparation process of the nearly spherical solder particles provided in the embodiment of the present invention;

[0040] Figure 2 This is a product picture of the nearly spherical solder prepared in Example 1 of the present invention;

[0041] Figure 3 This is a product picture of the nearly spherical solder prepared in Example 2 of the present invention.

[0042] Description of the drawings: 1-disc horseshoe-shaped hob; 11-disc; 12-horseshoe-shaped cutter; 2-laser absorption paint feeding device; 3-laser generator; 4-material collecting bin. DETAILED DESCRIPTION

[0043] The technical scheme of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and specific embodiments, but it will be understood by those skilled in the art that the following described embodiments are part of embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present invention. If specific conditions are not specified in the embodiments, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer is not specified in the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0044] like Figure 1 As shown, the first aspect of the present invention provides a method for processing a nearly spherical particle solder, comprising the following steps:

[0045] The solder wire is pre-cut into a pod shape, and a laser absorbing coating is coated on the pre-cut incision connection, and then the incision connection is melted by laser to obtain a nearly spherical particle solder.

[0046] After pre-cutting by the method of the present invention, the solder wire is not cut, and its shape is similar to a pod shape in which a plurality of beans are continuously arranged. The distances from the central axis at different circumferential positions are basically the same, and the solder wire will not be squeezed flat. Pre-cutting can form a plurality of pre-cut segments with the same length, and the wire diameter at the incision connection between the pre-cut segments becomes thinner, and the diameter change portion is in an arc-shaped transition, and it is easy to form a spherical shape after the incision connection is melted. Applying laser absorption coating on the incision connection can form a high-energy absorption zone at the thinnest diameter, and it can be melted at a lower laser power, and the energy consumption is low. At the same time, because other parts not coated with laser absorption coating have a large laser reflectivity, only the incision connection with the thinnest diameter has a large laser absorption rate, and the incision connection can be better positioned during laser melting, avoiding uneven size of the solder ball due to deviation, so that the size of the nearly spherical solder is easy to control, and the nearly spherical shape in the present invention also includes the spherical shape.

[0047] Traditional ball making uses precision cutting to grind columnar particles into balls, which requires equipment such as cutters, ball rolling machines, and ball grinders. The equipment is complex, the production process is long, and the material utilization rate is low. The material loss exceeds 1 / 3, causing great waste of high-cost materials. The method of the present invention uses less equipment, has a low production cost, and has a high material utilization rate with basically no loss.

[0048] The traditional laser droplet balling method requires high laser power, especially silver alloy and copper alloy have high reflectivity to laser, which requires higher laser power, which will increase the equipment cost, reduce efficiency, and make the size of the molten ball difficult to control. If laser absorption coating is only applied at the cutting point, only the applied point will be melted during laser cutting, and the section without pre-cut will still be flat, and the shearing of spherical particles cannot be achieved. If laser absorption coating is applied to the entire solder wire surface, and then the laser droplet balling method is used to prepare solder balls, although spherical solder can be formed, the laser power can also be reduced to a certain extent. However, since the entire ball needs to be melted, the laser power is still relatively high, and the full coating of laser absorption coating cannot play a positioning role, the size of the solder ball is not easy to control, and the coating components are also easy to enter the molten solder ball to form impurity inclusions. The method of the present invention can overcome the above-mentioned defects, significantly reduce laser power, reduce energy consumption, and the size of the nearly spherical solder is easy to control.

[0049] In some specific embodiments of the present invention, the solder wire includes any one of copper alloy wire, silver alloy wire, nickel alloy wire, and iron alloy wire. The method of the present invention is particularly suitable for solder wires with high laser reflectivity such as copper alloy wire and silver alloy wire.

[0050] In some specific embodiments of the present invention, the wire diameter of the solder wire and the length of a single pre-cut segment are matched with the diameter of the nearly spherical granular solder, and the solder wire size and pre-cut size can be determined according to the size of the required solder ball; generally, the wire diameter of the solder wire and the length of a single pre-cut segment can be set to be the same as the diameter of the required solder ball.

[0051] In some specific embodiments of the present invention, the diameter of the solder wire is 1-6 mm, for example, it can be any point value among 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, and 6 mm, or a range of values ​​consisting of any two point values. In other embodiments, the diameter of the solder wire can also be other values ​​according to the size of the required solder ball.

[0052] In some specific embodiments of the present invention, the diameter of the incision connection is 0.2mm-d / 2, where d is the wire diameter of the solder wire. The purpose of controlling the diameter of the incision connection to be ≥0.2mm is to avoid collision between the upper and lower cutters or deformation of the wire during the pre-cutting process, and the diameter of the incision connection is controlled not to exceed 1 / 2 of the wire diameter of the solder wire in order to ensure the pre-cutting effect to form a nearly spherical solder and reduce the laser fusing power.

[0053] In some specific embodiments of the present invention, the laser absorbing coating comprises the following components by mass percentage:

[0054] Graphite powder 40%-70%, high molecular organic material 4%-8%, thickener 2%-5% and solvent 20%-52%.

[0055] Black graphite powder can improve the laser absorption effect and form a high-energy absorption area at the incision connection. The role of the polymer organic material is to enhance the bonding ability between the coating and the metal substrate. In addition, the polymer organic material has low ash content and no residue during the brazing process, which does not affect the welding effect. The thickener is used to adjust the viscosity of the coating to meet the use requirements.

[0056] In some embodiments, typically but not limiting, for example, in the laser absorbing coating, the mass percentage of graphite powder can be any point value among 40%, 50%, 60%, 70% or a range value consisting of any two point values; the mass percentage of high molecular organic material can be any point value among 4%, 5%, 6%, 7%, 8% or a range value consisting of any two point values; the mass percentage of thickener can be any point value among 2%, 3%, 4%, 5% or a range value consisting of any two point values; the mass percentage of solvent can be any point value among 20%, 23%, 28%, 32%, 40%, 45%, 52% or a range value consisting of any two point values.

[0057] In some specific embodiments of the present invention, the particle size of the graphite powder used is less than 10 μm, preferably less than 5 μm. The use of graphite powder with a smaller particle size is conducive to the uniformity of graphite powder coating.

[0058] In some specific embodiments of the present invention, the graphite powder used is flake graphite powder.

[0059] In some specific embodiments of the present invention, the polymer organic material used includes at least one of polyacrylate, polyvinyl butyral ester, and polyvinyl pyrrolidone; the above polymer organic material has strong adhesion to metal, and the brazing process has low ash content and no residue, which does not affect the welding effect.

[0060] In some specific embodiments of the present invention, the thickener used includes methyl cellulose and / or ethyl cellulose.

[0061] In some specific embodiments of the present invention, the solvent used includes at least one of trichloroethylene, dichloroethylene, carbon tetrachloride, toluene, p-xylene, ethyl acetate, dimethyl sulfoxide, butyl acetate, methanol, ethanol, chloroform, and acetone.

[0062] In some specific embodiments of the present invention, the laser power required for laser fusing the incision connection is 500-5000W, for example, it can be any point value among 500W, 800W, 1000W, 1500W, 2000W, 3000W, 4000W, 5000W, or a range value consisting of any two point values.

[0063] A second aspect of the present invention provides a nearly spherical particle solder, which is produced by the processing method of the nearly spherical particle solder described in any one of the aforementioned embodiments.

[0064] like Figure 1 As shown, the third aspect of the present invention provides a processing device for nearly spherical particle solder, which is applicable to the processing method for nearly spherical particle solder described in any one of the aforementioned embodiments, comprising:

[0065] Two disc horseshoe cutters 1 symmetrically arranged with respect to the solder wire and with adjustable gaps are used to pre-cut the solder wire passing through the gaps therebetween. The disc horseshoe cutter 1 comprises a disc 11 and a plurality of horseshoe cutters 12 fixed on the disc 11. The plurality of horseshoe cutters 12 are evenly distributed around the circumference of the disc 11.

[0066] A laser absorbing paint feeding device 2, used for providing the laser absorbing paint to the horseshoe-shaped cutter 12;

[0067] A laser generator 3, which is located downstream of the disc horseshoe hob 1 and is used to fuse the pre-cut portion of the solder wire;

[0068] The material collecting bin 4 is used to collect the nearly spherical solder particles.

[0069] During pre-cutting, the gap between the two circular horseshoe cutters 1 can be adjusted according to the wire diameter and pre-cutting depth of the solder wire. The solder wire passes through the gap between the two circular horseshoe cutters 1. The two circular horseshoe cutters 1 rotate in opposite directions for pre-cutting. The pre-cutting process can ensure that the solder wire is straight, and during the rotation of the circular horseshoe cutter 1, the laser absorbing coating feeding device 2 can apply the laser absorbing coating to the horseshoe cutter 12. After pre-cutting by the horseshoe cutter 12, the solder wire forms a shape similar to a pod, and the wire diameter at the incision connection becomes thinner, and the solder wire is pressed with a layer of black laser absorbing coating by the blade head of the horseshoe cutter 12 at the thinned part, which is beneficial to the energy absorption during subsequent laser cutting. The nearly spherical granular solder obtained after laser melting enters the collecting bin 4.

[0070] In some specific embodiments of the present invention, two laser absorbing paint feeding devices 2 are provided, which are matched with two disc horseshoe-shaped roller cutters 1 respectively.

[0071] In some specific embodiments of the present invention, the laser absorbing paint feeding device 2 includes a paint box and a laser absorbing paint located in the paint box. The side wall of the paint box close to one end of the disc horseshoe-shaped roller 1 is a flexible porous material, and the flexible porous material can absorb the laser absorbing paint. The horseshoe-shaped cutter 12 passes through the paint box during rotation and comes into contact with the flexible porous material. The laser absorbing paint is dipped by squeezing and the laser absorbing paint is applied to the cut connection of the solder wire when pre-cutting the solder wire. The device can realize automatic feeding of the laser absorbing paint during the pre-cutting process and realize coating at the same time as pre-cutting. The operation is simple and the work efficiency is high.

[0072] In some specific embodiments of the present invention, the flexible porous material includes any one of sponge, cotton, and absorbent paper. The function of the flexible porous material is to absorb the laser absorbing coating and be squeezed during contact with the horseshoe cutter 12, releasing the laser absorbing coating and coating it on the cutter head.

[0073] In some specific embodiments of the present invention, the viscosity of the laser absorbing coating used is 2000-5000 cP, for example, it can be any point value among 2000 cP, 2500 cP, 3000 cP, 3500 cP, 4000 cP, 4500 cP, 5000 cP or a range value consisting of any two point values. Too high viscosity of the coating is not conducive to the adsorption of the flexible porous material; too low viscosity, the coating has good fluidity and is easy to seep out of the flexible porous material, so the viscosity of the laser absorbing coating needs to be reasonably controlled.

[0074] In some specific embodiments of the present invention, the material of the horseshoe cutter 12 includes any one of hard alloy, high speed steel, and superhard material. The materials of the multiple horseshoe cutters 12 on the same disk 11 can be the same or different.

[0075] In some specific embodiments of the present invention, the gap a between the two discs 11 satisfies the following conditions: a≥d, 0.2mm≤a-2h<d / 2, where d is the wire diameter of the solder wire, and h is the height of the blade of the horseshoe cutter, that is, the length of the horseshoe cutter extending out of the disc. The gap a between the two discs 11 refers to the minimum spacing between the two discs 11. The purpose of controlling the disc gap a≥d is to prevent the solder wire from being squeezed by the discs; a-2h is the minimum gap between the blades of the two disc horseshoe hobs 1. The purpose of controlling a-2h≥0.2mm is to avoid collision between the upper and lower blades or deformation of the solder wire. Controlling a-2h<d / 2 is to make the diameter of the incision connection smaller than 1 / 2 of the initial diameter of the solder wire to ensure the pre-cutting effect.

[0076] In some specific embodiments of the present invention, the rotational linear velocity V1 of the disc horseshoe cutter 1 and the wire feeding speed V2 of the solder wire satisfy: V2=lNV1 / [π(D+2h)], wherein l is the length of a single pre-cut segment, N is the number of horseshoe cutters on a single disc, D is the diameter of the disc, and h is the height of the blade head of the horseshoe cutter.

[0077] In some specific embodiments of the present invention, the laser generator is a YAG laser generator or a semiconductor laser generator.

[0078] In the following, some embodiments of the present invention are described in detail in conjunction with specific examples. The raw materials used in the examples can be purchased from the market unless otherwise specified. The following examples are all implemented using the device provided by the present invention.

[0079] Example 1

[0080] The ball is made of solder BAg72Cu alloy wire with a wire diameter of 3mm.

[0081] The horseshoe cutter is made of YT carbide, with a disc diameter of 30mm and a cutter head height h of 3mm. Four cutter heads are welded on the cutter disc, and the gap (a-2h) between the two disc horseshoe cutters is adjusted to 1mm.

[0082] Select flake graphite powder with a particle size of less than 5 μm, and mix 60% of graphite powder, 5% of polyacrylate, 3% of ethyl cellulose, 20% of trichloroethylene, and 12% of carbon tetrachloride by mass to form a uniform black coating with a coating viscosity of 3200 cP.

[0083] The disc horseshoe hob rotates in opposite directions, and the laser absorbing paint feeding device is placed on the side. During the rolling process of the disc horseshoe hob, the laser absorbing paint adheres to the horseshoe cutter head and is applied to the interface connection during pre-cutting. The disc horseshoe hob pre-cuts the solder wire, adjusts the wire feeding speed to 5mm / s and the linear speed of the disc horseshoe hob to 47.1mm / s, and pre-cuts the solder wire into a pod shape, where the length of a single pre-cut section is 3mm, the diameter of the solder wire cut connection is 1mm, and the solder wire cut connection is adhered with black laser absorbing paint.

[0084] A YAG laser generator with a power of 1000W is added to the rear end of the solder wire to melt the solder wire into a nearly spherical solder with a diameter of 3mm. The nearly spherical solder products are as follows: Figure 2 shown.

[0085] Example 2

[0086] The ball is made of solder BAg45CuZn alloy wire with a wire diameter of 1mm.

[0087] The horseshoe cutter is made of YG carbide, with a disc diameter of 20 mm and a cutter head height h of 3 mm. Eight cutter heads are welded on the cutter disc, and the gap (a-2h) between the two disc horseshoe cutters is adjusted to 0.2 mm.

[0088] Select flake graphite powder with a particle size of less than 8 μm, and mix 70% of graphite powder, 2% of polyacrylate, 2% of polyvinyl butyral, 3% of ethyl cellulose, 5% of p-xylene, 5% of methanol, and 13% of ethyl acetate, by mass percentage, to form a uniform black coating with a coating viscosity of 2600 cP.

[0089] The disc horseshoe hob rotates in opposite directions, and the laser absorbing paint feeding device is placed on the side. During the rolling process of the disc horseshoe hob, the laser absorbing paint adheres to the horseshoe cutter head and is applied to the interface connection during pre-cutting. The disc horseshoe hob pre-cuts the solder wire, adjusts the wire feeding speed to 5mm / s and the linear speed of the disc horseshoe hob to 51mm / s, and pre-cuts the solder wire into a pod shape, where the length of a single pre-cut section l is 1mm, the solder wire diameter change is 0.2mm, and the solder wire diameter change is adhered to black laser absorbing paint.

[0090] A YAG laser generator with a power of 800W is added to the rear end of the solder wire to melt the solder wire into a nearly spherical solder with a diameter of 1mm. The nearly spherical solder products are as follows: Figure 3 shown.

[0091] Example 3

[0092] The ball is made of 105 copper alloy wire with a wire diameter of 6mm.

[0093] The horseshoe cutter is made of PCD material, with a disc diameter of 40 mm and a cutter head height h of 4 mm. Three cutter heads are welded on the cutter disc, and the gap (a-2h) between the two disc horseshoe cutters is adjusted to 0.8 mm.

[0094] Select flake graphite powder with a particle size of less than 6 μm, and mix and stir, by mass percentage, 40% of graphite powder, 1% of polyacrylate, 2% of polyvinyl butyral, 1% of polyvinyl pyrrolidone, 2% of methyl cellulose, 2% of ethyl cellulose, 10% of ethyl acetate, 20% of dimethyl sulfoxide, and 22% of butyl acetate to form a uniform black coating with a coating viscosity of 2300 cP.

[0095] The disc horseshoe hob rotates in opposite directions, and the laser absorbing paint feeding device is placed on the side. During the rolling process of the disc horseshoe hob, the laser absorbing paint adheres to the horseshoe cutter head and is applied to the interface connection during pre-cutting. The disc horseshoe hob pre-cuts the solder wire, adjusts the wire feeding speed to 10mm / s and the linear speed of the disc horseshoe hob to 83.73mm / s, and pre-cuts the solder wire into a pod shape, where the length of a single pre-cut section is 6mm, the solder wire diameter is 0.8mm, and black graphite paint adheres to the solder wire diameter change.

[0096] A YAG laser generator with a power of 1500W is added to the rear end of the solder wire to melt the solder wire to form a nearly spherical solder with a diameter of 6mm.

[0097] Comparative Example 1

[0098] Comparative Example 1 is similar to Example 1, except that a disc horseshoe-shaped hob is directly used to cut the solder BAg72Cu alloy wire without laser melting. When only cutting is used, the knife needs to be adjusted to avoid collision between the upper and lower knives. Servo precision cutting is used to ensure cutting accuracy. Other equipment parameters are the same as Example 1. The particles obtained by cutting in this comparative example have a smooth fracture surface, and spherical cutting cannot be guaranteed.

[0099] Comparative Example 2

[0100] Comparative Example 2 is similar to Example 1, except that the solder BAg72Cu alloy wire is not pre-cut, the laser absorbing coating is directly applied to the cutting point, and laser cutting is used to melt through the coating point, and the laser power needs to reach 4000W to melt through. The cross section of the particles obtained in this comparative example without pre-cutting is still flat, and the shearing of spherical particles cannot be achieved.

[0101] Comparative Example 3

[0102] Comparative Example 3 is similar to Example 1, except that the solder BAg72Cu alloy wire is not pre-cut, a laser absorption coating is coated on the entire outer surface of the solder wire, and a spherical solder is prepared by a laser droplet sphering method. The required laser power is at least 9000 W for melting. The melting process requires a large laser power and it is difficult to control the droplet size.

[0103] Comparative Example 4

[0104] Comparative Example 4 is similar to Example 1, except that the solder BAg72Cu alloy wire is not pre-cut and is not coated with laser absorbing coating. The spherical solder is directly prepared by laser droplet sphering method. The required laser power is at least 18000W for melting. The melting process requires a large laser power and it is difficult to control the droplet size.

[0105] Comparative Example 5

[0106] In comparative example 5, a conventional method is used to cut a solder BAg72Cu alloy wire with a wire diameter of 3.2 mm into cylindrical segments with a length of 3.2 mm, and then grind the cylindrical segments into spherical solders with a diameter of 3 mm.

[0107] Test example

[0108] (1) The material utilization rates of Examples 1-3 and Comparative Examples 3-5 were tested respectively. The test results are shown in Table 1.

[0109] Table 1

[0110] sample Material utilization Example 1 99.97％ Example 2 99.68％ Example 3 99.35％ Comparative Example 3 98.56％ Comparative Example 4 97.63％ Comparative Example 5 41.20％

[0111] It can be seen from the data in Table 1 that the material utilization rate of the traditional grinding ball making in Comparative Example 5 is low, and there is a lot of material waste, while the material utilization rate of the method of the present invention is high, and there is basically no loss.

[0112] (2) Ten samples were randomly selected from the nearly spherical solder particles prepared in Examples 1-3 and Comparative Examples 3-5, and the diameter of the nearly spherical solder particles was tested. The test results are shown in Table 2.

[0113] Table 2

[0114]

[0115]

[0116] It can be seen from the data in Table 1 and Table 2 that the nearly spherical solder prepared by the method of the present invention has high material utilization, high dimensional accuracy and good uniformity; while the laser droplet sphering method, although the material utilization is also high, the droplet size is difficult to control, and the resulting product has low dimensional accuracy and poor uniformity; the traditional grinding sphering method, although the dimensional uniformity is good, has a very low material utilization rate, a large waste and a high cost; therefore, the method of the present invention has a better comprehensive effect.

[0117] Although the present invention has been illustrated and described with specific embodiments, it should be appreciated that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Those skilled in the art should understand that the technical solutions described in the above embodiments may be modified, or some or all of the technical features thereof may be replaced by equivalents without departing from the spirit and scope of the present invention. However, these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention. Therefore, this means that all such replacements and modifications within the scope of the present invention are included in the appended claims.

Claims

1. A method for processing nearly spherical solder particles, characterized in that: The following steps are involved: The solder wire is pre-cut into a pod shape, and a laser absorbing coating is coated on the incision connection formed by the pre-cutting, and then the incision connection is melted by laser to obtain the nearly spherical particle solder.

2. The method for processing the nearly spherical solder particles according to claim 1, characterized in that: Contains at least one of the following characteristics: (1) The solder wire comprises any one of copper alloy wire, silver alloy wire, nickel alloy wire and iron alloy wire; (2) The wire diameter of the solder wire and the length of a single pre-cut section both match the diameter of the nearly spherical solder particles; (3) The diameter of the incision connection is 0.2 mm-d / 2, where d is the wire diameter of the solder wire.

3. The method for processing the nearly spherical solder particles according to claim 1, characterized in that: The laser absorbing coating comprises the following components by mass percentage: Graphite powder 40%-70%, high molecular organic material 4%-8%, thickener 2%-5% and solvent 20%-52%.

4. The method for processing the nearly spherical solder particles according to claim 3, characterized in that: Contains at least one of the following characteristics: (1) The particle size of the graphite powder is less than 10 μm; (2) The polymer organic material includes at least one of polyacrylate, polyvinyl butyral, and polyvinyl pyrrolidone; (3) The thickener comprises methyl cellulose and / or ethyl cellulose; (4) The solvent includes at least one of trichloroethylene, dichloroethylene, carbon tetrachloride, toluene, p-xylene, ethyl acetate, dimethyl sulfoxide, butyl acetate, methanol, ethanol, chloroform and acetone.

5. The method for processing nearly spherical solder particles according to claim 1, characterized in that: The power of the laser is 500-5000W.

6. A nearly spherical particle solder, characterized in that: The solder is prepared by the processing method of the nearly spherical solder particles as described in any one of claims 1 to 5.

7. A processing device for nearly spherical solder particles, characterized in that: A method for processing the nearly spherical solder particles according to any one of claims 1 to 5, comprising: Two disc horseshoe cutters symmetrically arranged about the solder wire and with adjustable gaps are used to pre-cut the solder wire passing through the gaps therebetween, the disc horseshoe cutters comprising a disc and a plurality of horseshoe cutters fixed on the disc, the plurality of horseshoe cutters being evenly distributed around the circumference of the disc; a laser absorbing paint feeding device, used for providing the laser absorbing paint to the horseshoe-shaped cutter; A laser generator, the laser generator is located downstream of the disc horseshoe hob and is used to fuse the pre-cut portion of the solder wire; The material collecting bin is used to collect nearly spherical solder particles.

8. The processing device for nearly spherical solder particles according to claim 7, characterized in that: The laser absorbing paint feeding device includes a paint box and laser absorbing paint located in the paint box. The side wall of the paint box close to one end of the disc horseshoe-shaped roller is a flexible porous material. The horseshoe-shaped cutter passes through the paint box during rotation, contacts the flexible porous material and dips the laser absorbing paint, and applies the laser absorbing paint to the cut connection of the solder wire when pre-cutting the solder wire.

9. The processing device for nearly spherical solder particles according to claim 8, characterized in that: The flexible porous material includes at least one of sponge, cotton and absorbent paper; And / or, the viscosity of the laser absorbing coating is 2000-5000 cP.

10. The processing device for nearly spherical solder particles according to claim 7, characterized in that: Contains at least one of the following characteristics: (1) The material of the horseshoe cutter includes any one of cemented carbide, high-speed steel, and superhard material; (2) The gap a between the two disks satisfies the following conditions: a ≥ d, 0.2 mm ≤ a-2h < d / 2, where d is the wire diameter of the solder wire, and h is the height of the blade of the horseshoe-shaped cutter; (3) The rotational linear velocity V1 of the horseshoe-shaped hob and the feeding velocity V2 of the solder wire satisfy the following relationship: V2 = lNV1 / [π(D+2h)], wherein l is the length of a single pre-cut section, N is the number of horseshoe-shaped cutters on a single disk, and D is the diameter of the disk; (4) The laser generator is a YAG laser generator or a semiconductor laser generator.

Images