High-efficiency spray solder paste and its preparation method

Abstract

This invention discloses a high-efficiency spray solder paste and its preparation method, comprising the following raw materials in weight percentages: 75%–85% lead-free solder powder; the particle size of the lead-free solder powder is 15–25 μm; and 15%–25% flux; the flux is composed of the following raw materials in parts by weight: 15–25 parts polymerized rosin; 5–15 parts hydrogenated rosin; 5–10 parts rosin glyceryl ester; 3–5 parts ethyl palmitate; and 3–5 parts calcium chloride, etc. By using lead-free solder powder with a particle size of 15–25 μm, the cost is low. Combined with the flux formulated in this invention, this product can be sprayed using various spraying devices, replacing the traditional stencil printing method, effectively improving the efficiency of solder paste application. Furthermore, this solder paste exhibits excellent wettability during spraying, resulting in smooth spraying and stable solder joint quality, which is beneficial for improving the reliability and production efficiency of electronic products.

Description

Technical Field

[0001] This invention relates to the field of solder paste technology, and in particular to a high-efficiency spray solder paste and its preparation method. Background Technology

[0002] Solder paste, also known as solder paste, is a gray paste-like material. It's a new type of soldering material that emerged with the development of surface mount technology (SMT). It's a paste-like mixture of solder powder, flux, and other surfactants and thixotropic agents. It's primarily used in the SMT industry for soldering electronic components such as resistors, capacitors, and ICs on PCB surfaces. With the development of electronic products, they are becoming increasingly smaller, and solder pads are also shrinking. Changes in market technology mean that existing solder pastes can no longer meet market demands. The production of halogen-free solder paste using tiny solder powder plays a significant role in the electronic soldering of micro-solder joints. When applied to different industries and products, it can achieve high-tech, high-requirement, and micro-solder joint soldering, thus finding wide application in military, mobile phone, chip, medical, watchmaking, and other micro-solder joint soldering fields.

[0003] Currently, the solder powder used in solder pastes generally has a particle size of less than 10μm, which is very small and results in high cost. Furthermore, solder paste formed by mixing this solder powder with flux can usually only be applied using stencil printing, a method that is inefficient. This method also suffers from poor wetting, uneven printing, and inconsistent solder joint quality during printing, affecting the reliability and production efficiency of electronic products. Therefore, it is necessary to research a solution to address these problems. Summary of the Invention

[0004] In view of this, the present invention addresses the deficiencies of the prior art, and its main objective is to provide a high-efficiency spray solder paste and its preparation method, which can effectively solve the problems of high cost, stencil printing as a sole method, and poor wettability during printing of existing solder paste.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A high-efficiency spray solder paste is composed of the following raw materials in weight percentages:

[0007] 75%–85% lead-free solder powder;

[0008] The particle size of the lead-free solder powder is 15-25 μm;

[0009] Flux 15%–25%;

[0010] The flux is composed of the following raw materials in parts by weight:

[0011]

[0012] As a preferred embodiment, the lead-free solder powder is composed of four elements: tin, bismuth, silver, and copper, wherein the bismuth content is 15% to 25%, the copper content is 0.5% to 1.2%, the silver content is 0.8% to 4.5%, and the tin content is the balance.

[0013] As a preferred embodiment, the method for preparing the lead-free solder powder includes the following steps:

[0014] Step 1: Preparation of molten alloy:

[0015] (1) Select an appropriate amount of tin raw material and add bismuth-tin alloy, silver-tin alloy and copper-tin alloy into the melting furnace respectively;

[0016] (2) Heat the melting furnace to 250-360°C and maintain the melting time at 3.5-4.5 hours to obtain mixed liquid a;

[0017] Step 2, Polymerization reaction:

[0018] (1) The prepared mixed liquid a is put into the reaction vessel;

[0019] (2) Heating is carried out in a nitrogen or vacuum atmosphere, with a nitrogen injection rate of 1.8 l / min;

[0020] (3) Add organic antimony as a stabilizer, stir and heat to 500-600℃, and the polymerization reaction yields mixed liquid b;

[0021] Step 3: Cooling and Filtration

[0022] (1) Allow the mixed liquid b to cool naturally for 24–28 hours;

[0023] (2) Filter the mixed liquid b to obtain the filtrate;

[0024] Step 4: Grinding: Place the filtered material into a grinding device for grinding, so that the particle size is 15-25μm;

[0025] Step 5: Drying treatment:

[0026] (1) Put the ground filter material into a drying oven to dry;

[0027] (2) Heat the drying oven to 120-150°C and dry for 2-3 hours to obtain lead-free solder powder.

[0028] As a preferred embodiment, the polymerized rosin is RJH-145 polymerized rosin.

[0029] As a preferred embodiment, the hydrogenated rosin is AX-80 fully hydrogenated rosin.

[0030] A method for preparing high-efficiency spray solder paste includes the following steps:

[0031] (1) Weigh out the following ingredients in proportion: polymerized rosin, hydrogenated rosin, rosin glycerol ester, ethyl palmitate, calcium chloride, ethylene bis-12-hydroxystearamide, ethylene bisstearamide, oxidized polyethylene wax, 12-hydroxystearic acid, diethylene glycol butyl ether, triethylene glycol dibutyl ether, hexanediol, octanoic acid and sebacic acid.

[0032] (2) Add polymerized rosin, hydrogenated rosin, rosin glycerol ester, ethyl palmitate, calcium chloride, ethylene bis-12-hydroxystearamide, ethylene bisstearamide, oxidized polyethylene wax, 12-hydroxystearic acid, diethylene glycol butyl ether, triethylene glycol dibutyl ether, hexanediol, octanoic acid and sebacic acid to the same container, heat to 150℃~170℃ and stir until completely melted, cool to obtain a paste-like flux, and store in a cold storage at 0~10℃ for later use;

[0033] (3) Weigh out the lead-free solder powder and flux according to the proportion, pour them into a vacuum mixer, stir at low speed for 15-20 minutes, then fill with nitrogen and stir at medium speed for 50-60 minutes to make the lead-free solder powder and flux fully mixed and uniform, then vacuum and stir at medium speed for 10-15 minutes to obtain solder paste.

[0034] Compared with the prior art, the present invention has obvious advantages and beneficial effects. Specifically, as can be seen from the above technical solution:

[0035] By using lead-free solder powder with a particle size of 15-25μm, the cost is low. When used in conjunction with the flux formulated in this invention, this product can be sprayed using various spraying devices, replacing the traditional stencil printing method. This effectively improves the efficiency of solder paste application. Furthermore, the solder paste of this invention has excellent wettability during spraying, resulting in smooth spraying and stable solder joint quality, which is beneficial to improving the reliability and production efficiency of electronic products. Detailed Implementation

[0036] This invention discloses a high-efficiency spray solder paste, composed of the following raw materials in weight percentages:

[0037] 75%–85% lead-free solder powder;

[0038] The particle size of the lead-free solder powder is 15-25 μm;

[0039] Flux 15%–25%;

[0040] The flux is composed of the following raw materials in parts by weight:

[0041]

[0042] The lead-free solder powder is composed of four elements: tin, bismuth, silver, and copper. The bismuth content is 15%–25%, the copper content is 0.5%–1.2%, the silver content is 0.8%–4.5%, and the tin content is the balance. The polymerized rosin is RJH-145 polymerized rosin. The hydrogenated rosin is AX-80 fully hydrogenated rosin.

[0043] The preparation method of the lead-free solder powder includes the following steps:

[0044] Step 1: Preparation of molten alloy:

[0045] (1) Select an appropriate amount of tin raw materials and add bismuth-tin alloy, silver-tin alloy and copper-tin alloy into the melting furnace respectively.

[0046] (2) Heat the melting furnace to 250-360°C and maintain the melting time at 3.5-4.5 hours to obtain mixed liquid a.

[0047] Step 2, Polymerization reaction:

[0048] (1) The prepared mixed liquid a is put into the reactor.

[0049] (2) Heating is carried out in a nitrogen or vacuum atmosphere, with a nitrogen injection rate of 1.8 l / min.

[0050] (3) Add organic antimony as a stabilizer, stir and heat to 500-600℃, and the polymerization reaction yields mixed liquid b.

[0051] Step 3: Cooling and Filtration

[0052] (1) Allow the mixed liquid b to cool naturally for 24 to 28 hours.

[0053] (2) Filter the mixed liquid b to obtain the filtered material.

[0054] Step 4: Grinding: Place the filtered material into a grinding device for grinding, so that the particle size is 15-25μm.

[0055] Step 5: Drying treatment:

[0056] (1) Put the ground filter material into the drying oven to dry.

[0057] (2) Heat the drying oven to 120-150°C and dry for 2-3 hours to obtain lead-free solder powder.

[0058] This invention also discloses a method for preparing the aforementioned high-efficiency spray solder paste, comprising the following steps:

[0059] (1) Weigh out the following ingredients in proportion: polymerized rosin, hydrogenated rosin, rosin glycerol ester, ethyl palmitate, calcium chloride, ethylene bis-12-hydroxystearamide, ethylene bisstearamide, oxidized polyethylene wax, 12-hydroxystearic acid, diethylene glycol butyl ether, triethylene glycol dibutyl ether, hexanediol, octanoic acid and sebacic acid.

[0060] (2) Add polymerized rosin, hydrogenated rosin, rosin glycerol ester, ethyl palmitate, calcium chloride, ethylene bis-12-hydroxystearamide, ethylene bisstearamide, oxidized polyethylene wax, 12-hydroxystearic acid, diethylene glycol butyl ether, triethylene glycol dibutyl ether, hexanediol, octanoic acid and sebacic acid to the same container, heat to 150℃~170℃ and stir until completely melted, cool to obtain a paste-like flux, and store in a cold storage at 0~10℃ for later use.

[0061] (3) Weigh out the lead-free solder powder and flux according to the proportion, pour them into a vacuum mixer, stir at low speed for 15-20 minutes, then fill with nitrogen and stir at medium speed for 50-60 minutes to make the lead-free solder powder and flux fully mixed and uniform, then vacuum and stir at medium speed for 10-15 minutes to obtain solder paste.

[0062] The present invention will be further described in detail below with reference to several embodiments:

[0063] Example 1:

[0064] This embodiment discloses a high-efficiency spray solder paste, which is composed of the following raw materials in weight percentage:

[0065] 80% lead-free solder powder;

[0066] The particle size of the lead-free solder powder is 20μm;

[0067] 20% flux;

[0068] The flux is composed of the following raw materials in parts by weight:

[0069]

[0070]

[0071] The lead-free solder powder is composed of four elements: tin, bismuth, silver, and copper, with bismuth content of 18%, copper content of 0.8%, silver content of 2%, and tin as the balance. The polymerized rosin is RJH-145 polymerized rosin. The hydrogenated rosin is AX-80 fully hydrogenated rosin.

[0072] The preparation method of the lead-free solder powder includes the following steps:

[0073] Step 1: Preparation of molten alloy:

[0074] (1) Select an appropriate amount of tin raw materials and add bismuth-tin alloy, silver-tin alloy and copper-tin alloy into the melting furnace respectively.

[0075] (2) Heat the melting furnace to 300°C and maintain the melting time at 3.5 hours to obtain mixed liquid a.

[0076] Step 2, Polymerization reaction:

[0077] (1) The prepared mixed liquid a is put into the reactor.

[0078] (2) Heating is carried out in a nitrogen or vacuum atmosphere, with a nitrogen injection rate of 1.8 l / min.

[0079] (3) Add organic antimony as a stabilizer, stir and heat to 550°C, and the polymerization reaction yields mixed liquid b.

[0080] Step 3: Cooling and Filtration

[0081] (1) Allow the mixed liquid b to cool naturally for 25 hours.

[0082] (2) Filter the mixed liquid b to obtain the filtered material.

[0083] Step 4: Grinding: Place the filtered material into a grinding device for grinding, so that the particle size is 20μm.

[0084] Step 5: Drying treatment:

[0085] (1) Put the ground filter material into the drying oven to dry.

[0086] (2) Heat the drying oven to 130°C and dry for 2.3 hours to obtain lead-free solder powder.

[0087] This embodiment also discloses a method for preparing the aforementioned high-efficiency spray solder paste, which includes the following steps:

[0088] (1) Weigh out the following ingredients in proportion: polymerized rosin, hydrogenated rosin, rosin glycerol ester, ethyl palmitate, calcium chloride, ethylene bis-12-hydroxystearamide, ethylene bisstearamide, oxidized polyethylene wax, 12-hydroxystearic acid, diethylene glycol butyl ether, triethylene glycol dibutyl ether, hexanediol, octanoic acid and sebacic acid.

[0089] (2) Add polymerized rosin, hydrogenated rosin, rosin glycerol ester, ethyl palmitate, calcium chloride, ethylene bis-12-hydroxystearamide, ethylene bisstearamide, oxidized polyethylene wax, 12-hydroxystearic acid, diethylene glycol butyl ether, triethylene glycol dibutyl ether, hexanediol, octanoic acid and sebacic acid to the same container, heat to 160°C and stir until completely melted, cool to obtain a paste-like flux, and store in an 8°C cold storage for later use.

[0090] (3) Weigh out the lead-free solder powder and flux according to the proportion, pour them into a vacuum mixer, stir at low speed for 17 minutes, then fill with nitrogen and stir at medium speed for 55 minutes to make the lead-free solder powder and flux fully mixed and uniform. Then vacuum and stir at medium speed for 12 minutes to obtain solder paste.

[0091] Tests have shown that the high-efficiency spray solder paste prepared using the formula and method of this embodiment can be sprayed using various spraying devices, and its wetting time after spraying is 0.91s, with enhanced wetting power.

[0092] Example 2:

[0093] This embodiment discloses a high-efficiency spray solder paste, which is composed of the following raw materials in weight percentage:

[0094] 75% lead-free solder powder;

[0095] The particle size of the lead-free solder powder is 15μm;

[0096] 25% flux;

[0097] The flux is composed of the following raw materials in parts by weight:

[0098]

[0099]

[0100] The lead-free solder powder is composed of four elements: tin, bismuth, silver, and copper, with bismuth content of 20%, copper content of 0.5%, silver content of 0.8%, and tin as the balance. The polymerized rosin is RJH-145 polymerized rosin. The hydrogenated rosin is AX-80 fully hydrogenated rosin.

[0101] The preparation method of the lead-free solder powder includes the following steps:

[0102] Step 1: Preparation of molten alloy:

[0103] (1) Select an appropriate amount of tin raw materials and add bismuth-tin alloy, silver-tin alloy and copper-tin alloy into the melting furnace respectively.

[0104] (2) Heat the melting furnace to 250°C and maintain the melting time for 4 hours to obtain mixed liquid a.

[0105] Step 2, Polymerization reaction:

[0106] (1) The prepared mixed liquid a is put into the reactor.

[0107] (2) Heating is carried out in a nitrogen or vacuum atmosphere, with a nitrogen injection rate of 1.8 l / min.

[0108] (3) Add organic antimony as a stabilizer, stir and heat to 500℃, and the polymerization reaction yields mixed liquid b.

[0109] Step 3: Cooling and Filtration

[0110] (1) Allow the mixed liquid b to cool naturally for 26 hours.

[0111] (2) Filter the mixed liquid b to obtain the filtered material.

[0112] Step 4: Grinding: Place the filtered material into a grinding device for grinding, so that the particle size is 15μm.

[0113] Step 5: Drying treatment:

[0114] (1) Put the ground filter material into the drying oven to dry.

[0115] (2) Heat the drying oven to 120°C and dry for 2 hours to obtain lead-free solder powder.

[0116] This embodiment also discloses a method for preparing the aforementioned high-efficiency spray solder paste, which includes the following steps:

[0117] (1) Weigh out the following ingredients in proportion: polymerized rosin, hydrogenated rosin, rosin glycerol ester, ethyl palmitate, calcium chloride, ethylene bis-12-hydroxystearamide, ethylene bisstearamide, oxidized polyethylene wax, 12-hydroxystearic acid, diethylene glycol butyl ether, triethylene glycol dibutyl ether, hexanediol, octanoic acid and sebacic acid.

[0118] (2) Add polymerized rosin, hydrogenated rosin, rosin glycerol ester, ethyl palmitate, calcium chloride, ethylene bis-12-hydroxystearamide, ethylene bisstearamide, oxidized polyethylene wax, 12-hydroxystearic acid, diethylene glycol butyl ether, triethylene glycol dibutyl ether, hexanediol, octanoic acid and sebacic acid to the same container, heat to 150°C and stir until completely melted, cool to obtain a paste-like flux, and store in a 0°C cold storage for later use.

[0119] (3) Weigh out the lead-free solder powder and flux according to the proportion, pour them into a vacuum mixer, stir at low speed for 15 minutes, then fill with nitrogen and stir at medium speed for 50 minutes to make the lead-free solder powder and flux fully mixed and uniform. Then vacuum and stir at medium speed for 14 minutes to obtain solder paste.

[0120] Tests have shown that the high-efficiency spray solder paste prepared using the formula and method of this embodiment can be sprayed using various spraying devices, and its wetting time after spraying is 0.88s, with enhanced wetting power.

[0121] Example 3:

[0122] This embodiment discloses a high-efficiency spray solder paste, which is composed of the following raw materials in weight percentage:

[0123] 77% lead-free solder powder;

[0124] The particle size of the lead-free solder powder is 22μm;

[0125] Flux 23%;

[0126] The flux is composed of the following raw materials in parts by weight:

[0127]

[0128] The lead-free solder powder is composed of four elements: tin, bismuth, silver, and copper, with bismuth content of 25%, copper content of 1.1%, silver content of 3%, and tin as the balance. The polymerized rosin is RJH-145 polymerized rosin. The hydrogenated rosin is AX-80 fully hydrogenated rosin.

[0129] The preparation method of the lead-free solder powder includes the following steps:

[0130] Step 1: Preparation of molten alloy:

[0131] (1) Select an appropriate amount of tin raw materials and add bismuth-tin alloy, silver-tin alloy and copper-tin alloy into the melting furnace respectively.

[0132] (2) Heat the melting furnace to 360°C and maintain the melting time at 3.8 hours to obtain mixed liquid a.

[0133] Step 2, Polymerization reaction:

[0134] (1) The prepared mixed liquid a is put into the reactor.

[0135] (2) Heating is carried out in a nitrogen or vacuum atmosphere, with a nitrogen injection rate of 1.8 l / min.

[0136] (3) Add organic antimony as a stabilizer, stir and heat to 600℃, and the polymerization reaction yields mixed liquid b.

[0137] Step 3: Cooling and Filtration

[0138] (1) Allow the mixed liquid b to cool naturally for 24 hours.

[0139] (2) Filter the mixed liquid b to obtain the filtered material.

[0140] Step 4: Grinding: Place the filtered material into a grinding device for grinding, so that the particle size is 22μm.

[0141] Step 5: Drying treatment:

[0142] (1) Put the ground filter material into the drying oven to dry.

[0143] (2) Heat the drying oven to 150°C and dry for 2.5 hours to obtain lead-free solder powder.

[0144] This embodiment also discloses a method for preparing the aforementioned high-efficiency spray solder paste, which includes the following steps:

[0145] (1) Weigh out the following ingredients in proportion: polymerized rosin, hydrogenated rosin, rosin glycerol ester, ethyl palmitate, calcium chloride, ethylene bis-12-hydroxystearamide, ethylene bisstearamide, oxidized polyethylene wax, 12-hydroxystearic acid, diethylene glycol butyl ether, triethylene glycol dibutyl ether, hexanediol, octanoic acid and sebacic acid.

[0146] (2) Add polymerized rosin, hydrogenated rosin, rosin glycerol ester, ethyl palmitate, calcium chloride, ethylene bis-12-hydroxystearamide, ethylene bisstearamide, oxidized polyethylene wax, 12-hydroxystearic acid, diethylene glycol butyl ether, triethylene glycol dibutyl ether, hexanediol, octanoic acid and sebacic acid to the same container, heat to 170°C and stir until completely melted, cool to obtain a paste-like flux, and store in a 10°C cold storage for later use.

[0147] (3) Weigh out the lead-free solder powder and flux according to the proportion, pour them into a vacuum mixer, stir at low speed for 20 minutes, then fill with nitrogen and stir at medium speed for 60 minutes to make the lead-free solder powder and flux fully mixed and uniform. Then vacuum and stir at medium speed for 13 minutes to obtain solder paste.

[0148] Tests have shown that the high-efficiency spray solder paste prepared using the formula and method of this embodiment can be sprayed using various spraying devices, and its wetting time after spraying is 0.80s, with enhanced wetting power.

[0149] Example 4:

[0150] This embodiment discloses a high-efficiency spray solder paste, which is composed of the following raw materials in weight percentage:

[0151] 84% lead-free solder powder;

[0152] The particle size of the lead-free solder powder is 25 μm;

[0153] Flux 16%;

[0154] The flux is composed of the following raw materials in parts by weight:

[0155]

[0156]

[0157] The lead-free solder powder is composed of four elements: tin, bismuth, silver, and copper, with bismuth content of 23%, copper content of 1%, silver content of 4.5%, and tin as the balance. The polymerized rosin is RJH-145 polymerized rosin. The hydrogenated rosin is AX-80 fully hydrogenated rosin.

[0158] The preparation method of the lead-free solder powder includes the following steps:

[0159] Step 1: Preparation of molten alloy:

[0160] (1) Select an appropriate amount of tin raw materials and add bismuth-tin alloy, silver-tin alloy and copper-tin alloy into the melting furnace respectively.

[0161] (2) Heat the melting furnace to 320°C and maintain the melting time at 4.2 hours to obtain mixed liquid a.

[0162] Step 2, Polymerization reaction:

[0163] (1) The prepared mixed liquid a is put into the reactor.

[0164] (2) Heating is carried out in a nitrogen or vacuum atmosphere, with a nitrogen injection rate of 1.8 l / min.

[0165] (3) Add organic antimony as a stabilizer, stir and heat to 520°C, and the polymerization reaction yields mixed liquid b.

[0166] Step 3: Cooling and Filtration

[0167] (1) Allow the mixed liquid b to cool naturally for 28 hours.

[0168] (2) Filter the mixed liquid b to obtain the filtered material.

[0169] Step 4: Grinding: Place the filtered material into a grinding device for grinding, so that the particle size is 25μm.

[0170] Step 5: Drying treatment:

[0171] (1) Put the ground filter material into the drying oven to dry.

[0172] (2) Heat the drying oven to 125°C and dry for 3 hours to obtain lead-free solder powder.

[0173] This embodiment also discloses a method for preparing the aforementioned high-efficiency spray solder paste, which includes the following steps:

[0174] (1) Weigh out the following ingredients in proportion: polymerized rosin, hydrogenated rosin, rosin glycerol ester, ethyl palmitate, calcium chloride, ethylene bis-12-hydroxystearamide, ethylene bisstearamide, oxidized polyethylene wax, 12-hydroxystearic acid, diethylene glycol butyl ether, triethylene glycol dibutyl ether, hexanediol, octanoic acid and sebacic acid.

[0175] (2) Add polymerized rosin, hydrogenated rosin, rosin glycerol ester, ethyl palmitate, calcium chloride, ethylene bis-12-hydroxystearamide, ethylene bisstearamide, oxidized polyethylene wax, 12-hydroxystearic acid, diethylene glycol butyl ether, triethylene glycol dibutyl ether, hexanediol, octanoic acid and sebacic acid to the same container, heat to 155°C and stir until completely melted, cool to obtain a paste-like flux, and store in a 5°C cold storage for later use.

[0176] (3) Weigh out the lead-free solder powder and flux according to the proportion, pour them into a vacuum mixer, stir at low speed for 18 minutes, then fill with nitrogen and stir at medium speed for 53 minutes to make the lead-free solder powder and flux fully mixed and uniform. Then vacuum and stir at medium speed for 15 minutes to obtain solder paste.

[0177] Tests have shown that the high-efficiency spray solder paste prepared using the formula and method of this embodiment can be sprayed using various spraying devices, and its wetting time after spraying is 0.89s, with enhanced wetting power.

[0178] Example 5:

[0179] This embodiment discloses a high-efficiency spray solder paste, which is composed of the following raw materials in weight percentage:

[0180] 85% lead-free solder powder;

[0181] The particle size of the lead-free solder powder is 24 μm;

[0182] 15% flux;

[0183] The flux is composed of the following raw materials in parts by weight:

[0184]

[0185]

[0186] The lead-free solder powder is composed of four elements: tin, bismuth, silver, and copper, with bismuth content of 22%, copper content of 1.2%, silver content of 4%, and tin as the balance. The polymerized rosin is RJH-145 polymerized rosin. The hydrogenated rosin is AX-80 fully hydrogenated rosin.

[0187] The preparation method of the lead-free solder powder includes the following steps:

[0188] Step 1: Preparation of molten alloy:

[0189] (1) Select an appropriate amount of tin raw materials and add bismuth-tin alloy, silver-tin alloy and copper-tin alloy into the melting furnace respectively.

[0190] (2) Heat the melting furnace to 350°C and maintain the melting time at 4.5 hours to obtain mixed liquid a.

[0191] Step 2, Polymerization reaction:

[0192] (1) The prepared mixed liquid a is put into the reactor.

[0193] (2) Heating is carried out in a nitrogen or vacuum atmosphere, with a nitrogen injection rate of 1.8 l / min.

[0194] (3) Add organic antimony as a stabilizer, stir and heat to 580℃, and the polymerization reaction yields mixed liquid b.

[0195] Step 3: Cooling and Filtration

[0196] (1) Allow the mixed liquid b to cool naturally for 27 hours.

[0197] (2) Filter the mixed liquid b to obtain the filtered material.

[0198] Step 4: Grinding: Place the filtered material into a grinding device for grinding, so that the particle size is 24μm.

[0199] Step 5: Drying treatment:

[0200] (1) Put the ground filter material into the drying oven to dry.

[0201] (2) Heat the drying oven to 135°C and dry for 2.1 hours to obtain lead-free solder powder.

[0202] This embodiment also discloses a method for preparing the aforementioned high-efficiency spray solder paste, which includes the following steps:

[0203] (1) Weigh out the following ingredients in proportion: polymerized rosin, hydrogenated rosin, rosin glycerol ester, ethyl palmitate, calcium chloride, ethylene bis-12-hydroxystearamide, ethylene bisstearamide, oxidized polyethylene wax, 12-hydroxystearic acid, diethylene glycol butyl ether, triethylene glycol dibutyl ether, hexanediol, octanoic acid and sebacic acid.

[0204] (2) Add polymerized rosin, hydrogenated rosin, rosin glycerol ester, ethyl palmitate, calcium chloride, ethylene bis-12-hydroxystearamide, ethylene bisstearamide, oxidized polyethylene wax, 12-hydroxystearic acid, diethylene glycol butyl ether, triethylene glycol dibutyl ether, hexanediol, octanoic acid and sebacic acid to the same container, heat to 165°C and stir until completely melted, cool to obtain a paste-like flux, and store in a 7°C cold storage for later use.

[0205] (3) Weigh out the lead-free solder powder and flux according to the proportion, pour them into a vacuum mixer, stir at low speed for 19 minutes, then fill with nitrogen and stir at medium speed for 58 minutes to make the lead-free solder powder and flux fully mixed and uniform. Then vacuum and stir at medium speed for 10 minutes to obtain solder paste.

[0206] Tests have shown that the high-efficiency spray solder paste prepared using the formula and method of this embodiment can be sprayed using various spraying devices. After spraying, its wetting time is 0.84, and its wetting power is enhanced.

[0207] Example 6:

[0208] This embodiment discloses a high-efficiency spray solder paste, which is composed of the following raw materials in weight percentage:

[0209] 76% lead-free solder powder;

[0210] The particle size of the lead-free solder powder is 18μm;

[0211] Flux 24%;

[0212] The flux is composed of the following raw materials in parts by weight:

[0213]

[0214] The lead-free solder powder is composed of four elements: tin, bismuth, silver, and copper, with bismuth content of 15%, copper content of 0.9%, silver content of 3.5%, and tin as the balance. The polymerized rosin is RJH-145 polymerized rosin. The hydrogenated rosin is AX-80 fully hydrogenated rosin.

[0215] The preparation method of the lead-free solder powder includes the following steps:

[0216] Step 1: Preparation of molten alloy:

[0217] (1) Select an appropriate amount of tin raw materials and add bismuth-tin alloy, silver-tin alloy and copper-tin alloy into the melting furnace respectively.

[0218] (2) Heat the melting furnace to 330°C and maintain the melting time at 4.3 hours to obtain mixed liquid a.

[0219] Step 2, Polymerization reaction:

[0220] (1) The prepared mixed liquid a is put into the reactor.

[0221] (2) Heating is carried out in a nitrogen or vacuum atmosphere, with a nitrogen injection rate of 1.8 l / min.

[0222] (3) Add organic antimony as a stabilizer, stir and heat to 560℃, and the polymerization reaction yields mixed liquid b.

[0223] Step 3: Cooling and Filtration

[0224] (1) Allow the mixed liquid b to cool naturally for 25 hours.

[0225] (2) Filter the mixed liquid b to obtain the filtered material.

[0226] Step 4: Grinding: Place the filtered material into a grinding device for grinding until the particle size is 18μm.

[0227] Step 5: Drying treatment:

[0228] (1) Put the ground filter material into the drying oven to dry.

[0229] (2) Heat the drying oven to 140°C and dry for 2.8 hours to obtain lead-free solder powder.

[0230] This embodiment also discloses a method for preparing the aforementioned high-efficiency spray solder paste, which includes the following steps:

[0231] (1) Weigh out the following ingredients in proportion: polymerized rosin, hydrogenated rosin, rosin glycerol ester, ethyl palmitate, calcium chloride, ethylene bis-12-hydroxystearamide, ethylene bisstearamide, oxidized polyethylene wax, 12-hydroxystearic acid, diethylene glycol butyl ether, triethylene glycol dibutyl ether, hexanediol, octanoic acid and sebacic acid.

[0232] (2) Add polymerized rosin, hydrogenated rosin, rosin glycerol ester, ethyl palmitate, calcium chloride, ethylene bis-12-hydroxystearamide, ethylene bisstearamide, oxidized polyethylene wax, 12-hydroxystearic acid, diethylene glycol butyl ether, triethylene glycol dibutyl ether, hexanediol, octanoic acid and sebacic acid to the same container, heat to 158°C and stir until completely melted, cool to obtain a paste-like flux, and store in a 6°C cold storage for later use.

[0233] (3) Weigh out the lead-free solder powder and flux according to the proportion, pour them into a vacuum mixer, stir at low speed for 16 minutes, then fill with nitrogen and stir at medium speed for 52 minutes to make the lead-free solder powder and flux fully mixed and uniform. Then vacuum and stir at medium speed for 11 minutes to obtain solder paste.

[0234] Tests have shown that the high-efficiency spray solder paste prepared using the formula and method of this embodiment can be sprayed using various spraying devices, and its wetting time after spraying is 0.85s, with enhanced wetting power.

[0235] The key design feature of this invention is that by using lead-free solder powder with a particle size of 15-25μm, which is low in cost, and in conjunction with the flux formulated in this invention, this product can be sprayed and arranged using various spraying devices, replacing the traditional stencil printing method. This effectively improves the efficiency of solder paste arrangement. Furthermore, the solder paste of this invention has excellent wettability during spraying, resulting in smooth spraying and stable solder joint quality, which is beneficial to improving the reliability and production efficiency of electronic products.

[0236] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the technical scope of the present invention. Therefore, any minor modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A high-efficiency spray solder paste, characterized in that: It is composed of the following raw materials in the following mass percentages: 75%–85% lead-free solder powder; The particle size of the lead-free solder powder is 15-25 μm; Flux 15%–25%; The flux is composed of the following raw materials in parts by weight:

2. The high-efficiency spray solder paste according to claim 1, characterized in that: The lead-free solder powder is composed of four elements: tin, bismuth, silver, and copper. The bismuth content is 15%–25%, the copper content is 0.5%–1.2%, the silver content is 0.8%–4.5%, and the tin content is the balance.

3. The high-efficiency spray solder paste according to claim 1 or 2, characterized in that: The preparation method of the lead-free solder powder includes the following steps: Step 1: Preparation of molten alloy: (1) Select an appropriate amount of tin raw material and add bismuth-tin alloy, silver-tin alloy and copper-tin alloy into the melting furnace respectively; (2) Heat the melting furnace to 250-360°C and maintain the melting time at 3.5-4.5 hours to obtain mixed liquid a; Step 2, Polymerization reaction: (1) The prepared mixed liquid a is put into the reaction vessel; (2) Heating is carried out in a nitrogen or vacuum atmosphere, with a nitrogen injection rate of 1.8 l / min; (3) Add organic antimony as a stabilizer, stir and heat to 500-600℃, and the polymerization reaction yields mixed liquid b; Step 3: Cooling and Filtration (1) Allow the mixed liquid b to cool naturally for 24–28 hours; (2) Filter the mixed liquid b to obtain the filtrate; Step 4: Grinding: Place the filtered material into a grinding device for grinding, so that the particle size is 15-25μm; Step 5: Drying treatment: (1) Put the ground filter material into a drying oven to dry; (2) Heat the drying oven to 120-150°C and dry for 2-3 hours to obtain lead-free solder powder.

4. The high-efficiency spray solder paste according to claim 1, characterized in that: The polymerized rosin is RJH-145 polymerized rosin.

5. The high-efficiency spray solder paste according to claim 1, characterized in that: The hydrogenated rosin is AX-80 fully hydrogenated rosin.

6. A method for preparing high-efficiency spray solder paste as described in any one of claims 1-5, characterized in that: It includes the following steps: (1) Weigh out the following ingredients in proportion: polymerized rosin, hydrogenated rosin, rosin glycerol ester, ethyl palmitate, calcium chloride, ethylene bis-12-hydroxystearamide, ethylene bisstearamide, oxidized polyethylene wax, 12-hydroxystearic acid, diethylene glycol butyl ether, triethylene glycol dibutyl ether, hexanediol, octanoic acid and sebacic acid. (2) Add polymerized rosin, hydrogenated rosin, rosin glycerol ester, ethyl palmitate, calcium chloride, ethylene bis-12-hydroxystearamide, ethylene bisstearamide, oxidized polyethylene wax, 12-hydroxystearic acid, diethylene glycol butyl ether, triethylene glycol dibutyl ether, hexanediol, octanoic acid and sebacic acid to the same container, heat to 150℃~170℃ and stir until completely melted, cool to obtain a paste-like flux, and store in a cold storage at 0~10℃ for later use; (3) Weigh out the lead-free solder powder and flux according to the proportion, pour them into a vacuum mixer, stir at low speed for 15-20 minutes, then fill with nitrogen and stir at medium speed for 50-60 minutes to make the lead-free solder powder and flux fully mixed and uniform, then vacuum and stir at medium speed for 10-15 minutes to obtain solder paste.

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