A method for preparing a solder preform with flux

Abstract

This application relates to a method for preparing pre-formed solder with built-in flux, comprising the following steps: S1 Flux preparation, wherein the required flux is ground to a powder particle size between 25μm and 150μm; S2 Solder body preparation, wherein the solder body is a tin-based alloy; S3 Grinding the tin-based alloy into two or three particle sizes, wherein when there are two particle sizes, the coarse powder particle size is between 100-160μm and the fine powder particle size is between 20-45μm; when there are three particle sizes, the coarse powder particle size is between 100-160μm, the medium powder particle size is between 45-75μm, and the fine powder particle size is between 15-38μm; S4 Mixing the tin-based alloy powders of different particle sizes in a specific ratio; S5 Thoroughly mixing the flux powder and the solder body powder, wherein the flux accounts for 0.3%-5% of the total mass of the solder; S6 Extruding the mixed powder into a mold. This application is simple, convenient, low-cost, and provides uniform and accurate flux mixing.

Description

Technical Field

[0001] This application relates to a method for preparing preformed solder with built-in flux, which is mainly applicable to the preparation of solder materials for metallic materials. Background Technology

[0002] The existing methods for manufacturing preformed welding strips are basically as follows: Method 1: First, the alloy is batched and smelted; then, ingots are cast, strips are extruded, and then rolled and punched to obtain preformed welding strips. Flux is then applied to the surface of the welding strip using methods such as dip coating, thermal spraying, electrostatic spraying, or electrostatic vibration. The surface flux is then cured using methods such as resistance, infrared heating, or ultraviolet radiation. After cooling, the preformed welding strip of the desired shape is obtained through pressing and punching. Method 2: Using the above method, the welding strip body is manufactured through batching, smelting, casting, extrusion, rolling, and punching. Flux is applied to the welding strip through processes such as dip coating and spraying. The surface of the flux-coated welding strip is then dried to obtain the desired preformed welding strip.

[0003] Since the preformed solder sheets in these two processes are sheet-like and stacked, the flux must be prevented from sticking together before and after surface curing or drying. Furthermore, since most preformed solder sheets are small, special tooling equipment is needed to separate the semi-finished solder sheets when spraying flux onto the smaller punched solder sheets. The overall coating process is relatively complex and costly, and the content and uniformity of the flux coating cannot be precisely controlled, resulting in low overall efficiency. It is only suitable for the production of larger preformed solder sheets. Summary of the Invention

[0004] The technical problem solved by this application is to overcome the above-mentioned deficiencies in the prior art and to provide a simple, convenient, low-cost, and uniformly accurate flux preparation method for solder.

[0005] The technical solution adopted by this application to solve the above-mentioned technical problems is: a method for preparing pre-formed solder with built-in flux, characterized by including the following steps:

[0006] S1 flux preparation: The required flux should be ground until the powder particle size is between 25μm and 150μm.

[0007] S2 solder body preparation: The solder body is made of tin-based alloy, which is composed of tin and at least one of copper, lead, bismuth, antimony, silver and nickel.

[0008] S3 grinds tin-based alloys into two or three particle sizes. When there are two particle sizes, the coarse powder particle size is between 100-160 μm and the fine powder particle size is between 20-45 μm. When there are three particle sizes, the coarse powder particle size is between 100-160 μm, the medium powder particle size is between 45-75 μm, and the fine powder particle size is between 15-38 μm.

[0009] S4 tin-based alloy powders of different particle sizes are mixed in the following proportions: When there are two particle sizes, the proportion of coarse powder is 65%-85% of the total mass of the tin-based alloy, and the proportion of fine powder is 15%-35% of the total mass of the tin-based alloy; when there are three particle sizes, the proportion of coarse powder is 55%-65% of the total mass of the tin-based alloy, the proportion of medium powder is 10%-20% of the total mass of the tin-based alloy, and the proportion of fine powder is 20%-30% of the total mass of the tin-based alloy powder.

[0010] S5 thoroughly mixes the flux powder and the solder matrix (tin-based alloy) powder, wherein the flux accounts for 0.3%-5% of the total solder mass;

[0011] The powder mixed with S6 is extruded into shape using an extruder.

[0012] Step S6 includes:

[0013] The S61 powder is extruded through an extruder, with the height-to-diameter ratio controlled between 0.4 and 1.0 during extrusion to produce solder blanks.

[0014] S62 produces solder strip through an extrusion mechanism.

[0015] The raw materials used in this application are in powder form. Therefore, before extruding into strip, the powdered raw materials need to be initially compressed into large solid blocks (billets) before being extruded into strip. In addition, the powdered materials undergo two high-pressure processes to better ensure the density of the strip.

[0016] This application can also include an S7 step.

[0017] S7 rolls the solder strip to the required thickness.

[0018] This application can also include an S8 step.

[0019] S8 punches or laser-cuts the solder strip described in S7 into the desired shape.

[0020] The solder body described in this application uses SAC0307 or SAC305, and the solder body accounts for 98%-99% of the total solder mass.

[0021] The flux described in this application is composed of hydrogenated rosin, adipic acid, and benzotriazole.

[0022] The flux described in this application is composed of one, two, or three of the following: hydrogenated rosin, adipic acid, benzotriazole, chlorobrittle acid, diethylimidazole, and succinic acid.

[0023] Compared with the prior art, this application has the following advantages and effects: it is simple, convenient, low-cost, and the flux ratio is uniform and accurate. Detailed Implementation

[0024] The present application will be further described in detail below through specific embodiments. The following embodiments are explanations of the present application, but the present application is not limited to the following embodiments.

[0025] S1 flux preparation: The required flux should be ground until the powder particle size is between 25μm and 150μm.

[0026] S2 solder body preparation: The solder body is made of tin-based alloy, with tin as the main element and at least one of copper, lead, bismuth, antimony, silver and nickel as the remaining elements;

[0027] S3 The above-mentioned tin-based alloy is ground to produce two or three particle sizes. When there are two particle sizes, the coarse powder particle size is between 100-160μm and the fine powder particle size is between 20-45μm. When there are three particle sizes, the coarse powder particle size is between 100-160μm, the medium powder particle size is between 45-75μm, and the fine powder particle size is between 15-38μm.

[0028] S4 tin-based alloy powders of different particle sizes are mixed in the following proportions: When there are two particle sizes, the proportion of coarse powder is 65%-85% of the total mass of the tin-based alloy, and the proportion of fine powder is 15%-35% of the total mass of the tin-based alloy; when there are three particle sizes, the proportion of coarse powder is 55%-65% of the total mass of the tin-based alloy, the proportion of medium powder is 10%-20% of the total mass of the tin-based alloy, and the proportion of fine powder is 20%-30% of the total mass of the tin-based alloy powder.

[0029] S5 thoroughly mixes the flux powder and the solder bulk powder, wherein the flux accounts for 0.3%-5% of the total solder mass;

[0030] The powder mixed with S6 is extruded into shape using an extruder.

[0031] Step S6 includes:

[0032] The S61 powder is extruded through an extruder, with the height-to-diameter ratio controlled between 0.4 and 1.0 during extrusion to produce solder blanks.

[0033] S62 produces solder strip through an extrusion mechanism.

[0034] This application can also include an S7 step.

[0035] S7 rolls the solder strip to the required thickness.

[0036] This application can also include an S8 step.

[0037] S8 punches or laser-cuts the solder strip described in S7 into the desired shape.

[0038] Table 1 Flux Formulation

[0039]

[0040] Table 2 Particle size distribution of tin-based alloy powder

[0041]

[0042] Table 3 Specific Examples

[0043]

[0044] Note: The specific composition of SAC0307 and SAC305 refers to standard J-STD-006. Particle size refers to the diameter of the tin-based alloy powder.

[0045] This application has the following characteristics:

[0046] 1. It has no special requirements for the shaping of the flux when it is in solid state, making it easier to manufacture and less prone to sticking;

[0047] 2. The flux content can be precisely controlled according to requirements;

[0048] 3. The flux is distributed very evenly, avoiding the risk of uneven flux coating thickness in existing technologies;

[0049] 4. More precise surface dimensions;

[0050] 5. No special tooling or molds are required, resulting in high efficiency;

[0051] 6. The flux is evenly distributed inside the main material and will not be damaged during transportation and use.

Claims

1. A method for preparing pre-formed solder with built-in flux, characterized in that: Includes the following steps: S1 flux preparation: The required flux should be ground until the powder particle size is between 25μm and 150μm. S2 solder body preparation: The solder body is made of tin-based alloy, which is composed of tin and at least one of copper, lead, bismuth, antimony, silver and nickel. S3 grinds tin-based alloys into two or three particle sizes. When there are two particle sizes, the coarse powder particle size is between 100-160 μm and the fine powder particle size is between 20-45 μm. When there are three particle sizes, the coarse powder particle size is between 100-160 μm, the medium powder particle size is between 45-75 μm, and the fine powder particle size is between 15-38 μm. S4 tin-based alloy powders of different particle sizes are mixed in the following proportions: When there are two particle sizes, the proportion of coarse powder is 65%-85% of the total mass of the tin-based alloy, and the proportion of fine powder is 15%-35% of the total mass of the tin-based alloy; when there are three particle sizes, the proportion of coarse powder is 55%-65% of the total mass of the tin-based alloy, the proportion of medium powder is 10%-20% of the total mass of the tin-based alloy, and the proportion of fine powder is 20%-30% of the total mass of the tin-based alloy. S5 thoroughly mixes the flux powder and the solder bulk powder, wherein the flux accounts for 0.3%-5% of the total solder mass; The powder after S6 mixing is extruded into shape using an extruder: Step S6 includes: The S61 powder is extruded through an extruder, with the height-to-diameter ratio controlled between 0.4 and 1.0 during extrusion to produce solder blanks. S62 produces solder strips through an extrusion mechanism.

2. The method for preparing pre-formed solder with built-in flux according to claim 1, characterized in that: It also includes an S7 step. S7 rolls the solder strip to the required thickness.

3. The method for preparing pre-formed solder with built-in flux according to claim 2, characterized in that: Also, step S8 is set. S8 punches or laser-cuts the solder strip described in S7 into the desired shape.

4. The method for preparing pre-formed solder with built-in flux according to claim 1, characterized in that: The solder body is made of SAC0307 or SAC305, and the solder body accounts for 98%-99% of the total solder mass.

5. The method for preparing pre-formed solder with built-in flux according to claim 1, characterized in that: The flux is composed of hydrogenated rosin, adipic acid, and benzotriazole.

6. The method for preparing pre-formed solder with built-in flux according to claim 1, characterized in that: The flux is composed of one, two, or three of the following: hydrogenated rosin, adipic acid, benzotriazole, chlorobrittle acid, diethylimidazole, and succinic acid.

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