CN109848603B - Lead-free solder paste and preparation method thereof - Google Patents
Lead-free solder paste and preparation method thereof Download PDFInfo
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- CN109848603B CN109848603B CN201910210569.3A CN201910210569A CN109848603B CN 109848603 B CN109848603 B CN 109848603B CN 201910210569 A CN201910210569 A CN 201910210569A CN 109848603 B CN109848603 B CN 109848603B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
- B23K35/02—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by mechanical features, e.g. shape
- B23K35/0222—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by mechanical features, e.g. shape for use in soldering, brazing
- B23K35/0244—Powders, particles or spheres; Preforms made therefrom
- B23K35/025—Pastes, creams, slurries
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
- B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
- B23K35/24—Selection of soldering or welding materials proper
- B23K35/26—Selection of soldering or welding materials proper with the principal constituent melting at less than 400 degrees C
- B23K35/262—Sn as the principal constituent
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
- B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
- B23K35/36—Selection of non-metallic compositions, e.g. coatings, fluxes; Selection of soldering or welding materials, conjoint with selection of non-metallic compositions, both selections being of interest
- B23K35/3612—Selection of non-metallic compositions, e.g. coatings, fluxes; Selection of soldering or welding materials, conjoint with selection of non-metallic compositions, both selections being of interest with organic compounds as principal constituents
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
- B23K35/40—Making wire or rods for soldering or welding
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Electric Connection Of Electric Components To Printed Circuits (AREA)
- Compositions Of Macromolecular Compounds (AREA)
- Adhesives Or Adhesive Processes (AREA)
Abstract
The invention discloses a lead-free novel solder paste and a preparation method thereof, and the technical scheme is as follows: the components by weight are as follows: 84.8-90.6% of tin powder, 8.2-13.8% of soldering flux and 1.2-3.8% of dispersing agent, wherein the tin powder consists of 2.8-4.5% of Ag, 1.5-2.1% of Cu, 0.5-1.2% of Bi, 0.1-0.5% of Sb and the balance of Sn, the soldering flux consists of 36.4-47.3% of rosin, 19.9-30.6% of solvent, 6.2-15.1% of thixotropic agent, 14.3-22.5% of active agent and 1.2-5.6% of antioxidant component, and the tin powder and the soldering flux are optimized to enable the soldering flux to have higher activity and good wettability, so that the tin paste can still keep good soldering activity under continuous high-temperature baking, the generation of an oxide film on the surface of the solder during reflow soldering heating is inhibited, good contact of the solder and the tin paste is ensured, and the generation of pillow effect is prevented.
Description
Technical Field
The invention belongs to the technical field of welding materials, and particularly relates to novel lead-free solder paste and a preparation method thereof.
Background
The solder paste is a paste body formed by uniformly mixing uniform solder powder and stable soldering flux according to a certain proportion, and leads or end points of surface-assembled components and parts can form alloy connection with pads on a PCB (printed circuit board) during welding. However, when BGA or CAP is assembled on PCB printed boards, the Pillow effect (HIP) generated is very annoying to the electronic manufacturing industry.
The pillow effect is used for describing the bad welding phenomenon that the BGA welding balls and the solder paste are not completely fused together in the high-temperature process of Reflow (Reflow) of the BGA part of the circuit board, and a welding shape similar to a cold welding or a false welding of a head rest on a pillow is formed. The main reasons for the formation of the pillow effect are: firstly, the process problem is that the accuracy of the chip mounter is insufficient, and the XY position and the angle are not adjusted well, so that the solder ball of the BGA is dislocated with the solder paste; secondly, the PCB or BGA carrier plate has poor heat resistance and is easy to warp and deform at high temperature, so that the solder balls cannot contact with the solder paste; the activity of the soldering flux is weak, active ingredients of the soldering flux volatilize too early in the reflow high-temperature process, the activity performance is lost, the soldering performance is greatly reduced, the surface of the solder is covered by an oxide film, and the GBA solder ball and the solder paste interface cannot be well wetted by the oxide film, so that the solder paste and the BGA solder ball are not completely fused into a whole, and the pillow-shaped poor soldering is caused.
Therefore, there is an urgent need in the art to develop a lead-free solder paste with high activity, which can maintain good activity even under the continuous baking at high temperature of reflow soldering, and avoid the pillow effect caused by weak activity of the solder paste.
Disclosure of Invention
The lead-free solder paste disclosed by the invention has the advantages that the components of the solder powder and the soldering flux are optimized, so that the solder paste has higher activity and good wettability, the solder paste still keeps good welding activity under continuous high-temperature baking, the generation of an oxide film on the surface of the solder during the heating period of reflow soldering is inhibited, the good contact between the solder and the solder paste is ensured, and the generation of a pillow effect is prevented.
The invention also aims to provide a preparation method of the lead-free tin paste.
The invention relates to a lead-free solder paste which comprises the following components in parts by weight: 84.8-90.6% of tin powder, 8.2-13.8% of soldering flux and 1.2-3.8% of dispersing agent;
the tin powder comprises the following components in parts by weight: 2.8-4.5% of Ag, 1.5-2.1% of Cu, 0.5-1.2% of Bi, 0.1-0.5% of Sb and the balance of Sn;
the soldering flux consists of the following components in parts by weight: 36.4-47.3% of rosin, 19.9-30.6% of solvent, 6.2-15.1% of thixotropic agent, 14.3-22.5% of active agent and 1.2-5.6% of antioxidant.
Preferably, the rosin is any one of tall oil rosin, hydrogenated rosin and disproportionated rosin. The preferable rosin is AT04 disproportionated rosin produced by Guitian chemical company, the softening point is 80 ℃, the acid value is 160mgKOH/g, the rosin is a modified rosin obtained by eliminating conjugate double bonds easy to oxidize on the rosin, has higher inoxidizability, does not show activity under the action of a protective film AT normal temperature, but is activated under the high temperature of reflow soldering, quickly removes the oxide film on the surfaces of solder and parent metal in a short time, forms a protective film for preventing metal from reoxidizing on the surface of the solder, is favorable for inhibiting the generation of the oxide film on the surface of the solder during the heating of the reflow soldering, and ensures that the solder paste can still keep good soldering activity under continuous high-temperature baking.
Preferably, the solvent is composed of a plurality of diethylene glycol monobutyl ether, triethylene glycol methyl ether, propylene glycol phenyl ether, diethylene glycol mono-octyl ether and tripropylene glycol butyl ether. The solvent has the advantages that the ether melting point is high, the dissolving capacity to rosin is strong, the main effect of the solvent is to dissolve solid components in the soldering flux, so that the solid components form an even solution, the soldering flux is convenient for uniformly coating a proper amount of soldering paste components on a to-be-welded element, and meanwhile, the solvent can also clean dirt and oil stains on the surface of metal. The preferable solvent is a composite solvent consisting of diethylene glycol monobutyl ether (boiling point 231 ℃) and triethylene glycol methyl ether (231 ℃), has a higher melting point, and prevents the solvent from volatilizing in advance and the activity of the soldering flux from volatilizing and losing too early.
Preferably, the thixotropic agent is one or more of hardened castor oil, polyamide modified hydrogenated castor oil, octadecyl stearic acid amide and oleic acid amide. The main function of the thixotropic agent is to adjust the viscosity of the solder paste and to change the rheological properties of the flux. The preferred thixotropic agent is CRAYVALLACSF polyamide modified hydrogenated castor oil produced by the company Akema, and the polyamide modified hydrogenated castor oil has good sag resistance and temperature resistance, can adjust the rheological property and heat resistance of the soldering flux in high-temperature reflow soldering, enables the solder paste to still keep good activity at high temperature, and prevents the active ingredients of the solder paste from volatilizing prematurely to cause the pillow effect.
Preferably, the active agent is composed of two or more of DL-malic acid, citric acid, monoisopropanolamine and triisopropanolamine. The activator of the invention is preferably the combination of organic acid DL-malic acid and organic amine monoisopropanolamine, the organic acid DL-malic acid has the advantages of higher activity and extremely low corrosivity, the organic amine is used as an acidity regulator and has an acid-base compounding neutralization reaction with the organic acid at normal temperature, the precipitation of the organic acid of the activator at low temperature is prevented from weakening the activity of the soldering flux, the compounding product is rapidly decomposed into the organic acid and the organic amine in the continuous rising process of the reflow soldering temperature, the organic acid and the organic amine are both activators, the activity of the soldering flux is improved, oxides on the surfaces of the molten solder and the bonding pad are removed, a protective layer is formed and prevented from being oxidized again, thus the wettability between the solder and the bonding pad is improved, the wettability of the soldering interface is promoted to form excellent soldering effect, and the soldering paste can still maintain excellent soldering activity under continuous high-temperature baking, the pillow effect is avoided.
Preferably, the antioxidant is one or a combination of 2, 6-di-tert-butyl-p-cresol, ethoxyquinoline, 2-ethyl ether oxazole and methylbenzotriazole. The function of the solder paste is to prevent the solder flux from oxidative deterioration, improve the oxidation resistance of the solder paste, inhibit the oxidation of the solder paste and reduce the occurrence of pillow effect.
Preferably, the particle size of the tin powder is 30-60 mu m. The tin powder disclosed by the invention comprises 3-4% of Ag, 1.5-2% of Cu, 0.5-1.0% of Bi, 0.1-0.5 Sb and the balance of Sn, wherein the trace Bi and Sb can enhance the material strength of the tin paste, and meanwhile, the tin paste is a lead-free solder, so that the harm to human bodies is avoided and the environmental pollution is reduced.
Preferably, the dispersant is selected from one or a combination of oleamide, ethylene bis stearamide and ammonium polyacryl dimethyl taurate, and the function of the dispersant is to prevent tin paste from layering.
A preparation method of lead-free solder paste comprises the following steps:
s1, weighing the components according to the weight percentage for later use;
s2, adding a solvent into a container, heating to 110-130 ℃, then adding rosin, and stirring until the rosin is completely dissolved;
s3, after the rosin is completely dissolved, keeping the temperature at 110-130 ℃, adding the thixotropic agent into a container, keeping the temperature and stirring until the thixotropic agent is completely dissolved;
s4, cooling the temperature to 50-80 ℃, adding an active agent and an antioxidant, keeping the temperature and stirring for 20-30 minutes;
s5, grinding the mixture obtained in the step S4 by a grinder to obtain soldering flux;
and S6, adding 9-13 wt% of the soldering flux obtained in the step S5, 85-89 wt% of tin powder and 1-4 wt% of a dispersing agent into a tin paste stirrer, mixing and stirring for 30-60 minutes, and refrigerating at 0-5 ℃ to obtain the lead-free tin paste.
Preferably, the grinding in the step S5 is to grind the mixture to a particle size of less than 20 microns by a grinder at a rotating speed of 3000-5000 r/min. After grinding, the tin powder can be better dispersed in the soldering flux, so that the tin paste has better soldering activity.
Compared with the prior art, the invention has the following advantages:
the lead-free tin paste comprises tin powder, soldering flux and a dispersing agent, and has high activity and good wettability by optimizing the components of the tin powder and the soldering flux, so that the tin paste still keeps good soldering activity under continuous high-temperature baking, the generation of an oxide film on the surface of solder during reflow soldering heating is inhibited, the good contact between the solder and the tin paste is ensured, and the generation of a pillow effect is prevented; the soldering flux is compounded by rosin, a thixotropic agent, an active agent, a solvent and an antioxidant; the activator selects DL-malic acid, citric acid, monoisopropanolamine and triisopropanolamine, is a compound combination of organic acid and organic amine, has higher activity and extremely low corrosivity, the organic amine is used as an acidity regulator and has an acid-base compound neutralization reaction with the organic acid at normal temperature, the precipitation of the organic acid serving as the activator at low temperature is prevented from weakening the activity of the soldering flux, a compound product is rapidly decomposed into the organic acid and the organic amine serving as the activator at the reflow soldering temperature, the activity of the soldering flux is improved, oxides on the surfaces of molten solder and a bonding pad are removed, a protective layer is formed, and the re-oxidation of the molten solder and the bonding pad is prevented, so that the wettability between the solder and the bonding pad is improved; the thixotropic agent is prepared from hardened castor oil, polyamide modified hydrogenated castor oil, octadecyl stearic acid amide and oleic acid amide, has good sagging resistance and temperature resistance, can adjust the rheological property and heat resistance of the soldering flux in high-temperature reflow soldering, ensures that the tin paste still keeps good activity at high temperature, and prevents the active ingredients of the tin paste from being volatilized early; the rosin is selected from floating oil rosin, hydrogenated rosin and disproportionated rosin which have high oxidation resistance, do not have activity under the action of a protective film at normal temperature, but have activity activated under the high temperature of reflow soldering, rapidly remove the oxide film on the surfaces of the solder and the parent metal in a short time, and simultaneously form a protective film for preventing metal from being reoxidized on the surface of the solder, thereby being beneficial to inhibiting the generation of the oxide film on the surface of the solder during the heating of the reflow soldering; the antioxidant and the solvent are matched to promote the wettability of the welding interface so as to form an excellent welding effect, so that the solder paste can still keep good welding activity under continuous high-temperature baking, and the generation of pillow effect defects is reduced; in addition, the tin powder comprises 3-4% of Ag, 1.5-2% of Cu, 0.5-1.0% of Bi, 0.1-0.5 Sb and the balance of Sn, the material strength of the tin paste can be enhanced by trace Bi and Sb, and the tin paste does not contain lead and halogen, is safe to use and is environment-friendly.
The preparation method of the lead-free tin paste is simple and convenient in process, mild in reaction and suitable for large-scale continuous production.
Detailed Description
The following is a detailed description of the present invention:
the specific technical scheme of the invention is described by combining specific embodiments 1-6:
example 1:
the lead-free solder paste comprises 85.12% of solder powder, 11.92% of soldering flux and 2.96% of dispersant by weight, wherein the component proportion of the solder powder is shown in Table 2, the component proportion of the soldering flux is shown in Table 3, and the dispersant is oleamide; the preparation method comprises the following steps:
weighing the components according to the weight percentages in the tables 2 and 3 for later use; firstly, adding a solvent into a container, heating to 110 ℃, then adding rosin, stirring until the rosin is completely dissolved, keeping the temperature at 110 ℃, adding a thixotropic agent into the container, keeping the temperature and stirring until the thixotropic agent is completely dissolved; cooling to 60 deg.C, adding active agent and antioxidant, maintaining the temperature and stirring for 30 min; grinding the mixture by a grinder at the rotating speed of 4000r/min until the particle size is less than 20 microns to obtain the soldering flux; adding 11.92% of soldering flux, 85.12% of tin powder and 2.96% of dispersing agent into a tin paste stirrer, mixing and stirring for 50 minutes, and refrigerating at0 ℃ to obtain the lead-free tin paste.
Example 2:
the lead-free solder paste comprises 84.8% of solder powder, 13.8% of soldering flux and 1.4% of dispersant by weight, wherein the component proportion of the solder powder is shown in Table 2, the component proportion of the soldering flux is shown in Table 3, and the dispersant is prepared by mixing ethylene bis stearamide and polyacrylamide dimethyl ammonium taurate 1: 1; the preparation method comprises the following steps:
weighing the components according to the weight percentages in the tables 2 and 3 for later use; adding a solvent into a container, heating to 130 ℃, then adding rosin, stirring until the rosin is completely dissolved, keeping the temperature at 130 ℃, adding a thixotropic agent into the container, keeping the temperature and stirring until the thixotropic agent is completely dissolved; cooling to 50 deg.C, adding active agent and antioxidant, maintaining the temperature and stirring for 25 min; grinding the mixture by a grinder at the rotating speed of 5000r/min until the particle size is less than 20 microns to obtain the soldering flux; adding 13.8% of soldering flux, 84.8% of tin powder and 1.4% of dispersing agent into a tin paste stirrer, mixing and stirring for 30 minutes, and refrigerating at0 ℃ to obtain the lead-free tin paste.
Example 3:
the lead-free solder paste comprises 86.11 wt% of solder powder, 10.09 wt% of soldering flux and 3.8 wt% of a dispersing agent, wherein the component proportion of the solder powder is shown in Table 2, the component proportion of the soldering flux is shown in Table 3, and the dispersing agent is ethylene bis stearamide; the preparation method comprises the following steps:
weighing the components according to the weight percentages in the tables 2 and 3 for later use; adding a solvent into a container, heating to 120 ℃, then adding rosin, stirring until the rosin is completely dissolved, keeping the temperature at 120 ℃, adding a thixotropic agent into the container, keeping the temperature and stirring until the thixotropic agent is completely dissolved; cooling to 80 deg.C, adding active agent and antioxidant, maintaining the temperature and stirring for 20 min; grinding the mixture by a grinder at the rotating speed of 3000r/min until the particle size is less than 20 microns to obtain the soldering flux; and adding 10.09% of soldering flux, 86.11% of tin powder and 3.8% of dispersing agent into a tin paste stirrer, mixing and stirring for 60 minutes, and refrigerating at the temperature of 2 ℃ to obtain the lead-free tin paste.
Example 4:
the lead-free solder paste comprises 88.61 wt% of solder powder, 9.78 wt% of soldering flux and 1.61 wt% of a dispersing agent, wherein the component proportion of the solder powder is shown in Table 2, the component proportion of the soldering flux is shown in Table 3, and the dispersing agent is prepared by mixing oleamide and ethylene bis stearamide in a ratio of 1: 1; the preparation method comprises the following steps:
weighing the components according to the weight percentages in the tables 2 and 3 for later use; adding a solvent into a container, heating to 120 ℃, then adding rosin, stirring until the rosin is completely dissolved, keeping the temperature at 120 ℃, adding a thixotropic agent into the container, keeping the temperature and stirring until the thixotropic agent is completely dissolved; cooling to 60 deg.C, adding active agent and antioxidant, maintaining the temperature and stirring for 20 min; grinding the mixture by a grinder at the rotating speed of 5000r/min until the particle size is less than 20 microns to obtain the soldering flux; adding 9.78% of soldering flux, 88.61% of tin powder and 1.61% of dispersing agent into a tin paste stirrer, mixing and stirring for 30 minutes, and refrigerating at 5 ℃ to obtain the lead-free tin paste.
Example 5:
the lead-free tin paste comprises, by weight, 87.64% of tin powder, 9.12% of soldering flux and 3.24% of a dispersing agent, wherein the component proportion of the tin powder is shown in Table 2, the component proportion of the soldering flux is shown in Table 3, and the dispersing agent is ammonium polyacryl dimethyl taurate;
the preparation method comprises the following steps:
weighing the components according to the weight percentages in the tables 2 and 3 for later use; adding a solvent into a container, heating to 110 ℃, then adding rosin, stirring until the rosin is completely dissolved, keeping the temperature at 110 ℃, adding a thixotropic agent into the container, keeping the temperature and stirring until the thixotropic agent is completely dissolved; cooling to 70 deg.C, adding active agent and antioxidant, maintaining the temperature and stirring for 25 min; grinding the mixture by a grinder at the rotating speed of 3000r/min until the particle size is less than 20 microns to obtain the soldering flux; adding 9.12% of soldering flux, 87.64% of tin powder and 3.24% of dispersing agent into a tin paste stirrer, mixing and stirring for 40 minutes, and refrigerating at0 ℃ to obtain the lead-free tin paste.
Example 6:
the lead-free solder paste comprises, by weight, 90.60% of solder powder, 8.2% of soldering flux and 1.2% of dispersing agent, wherein the component proportion of the solder powder is shown in Table 2, the component proportion of the soldering flux is shown in Table 3, and the dispersing agent is prepared by mixing oleamide and ethylene bis stearamide in a ratio of 1: 1; the preparation method comprises the following steps:
weighing the components according to the weight percentages in the tables 2 and 3 for later use; adding a solvent into a container, heating to 120 ℃, then adding rosin, stirring until the rosin is completely dissolved, keeping the temperature at 120 ℃, adding a thixotropic agent into the container, keeping the temperature and stirring until the thixotropic agent is completely dissolved; cooling to 60 deg.C, adding active agent and antioxidant, maintaining the temperature and stirring for 20 min; grinding the mixture by a grinder at the rotating speed of 3000r/min until the particle size is less than 20 microns to obtain the soldering flux; adding 8.2% of soldering flux, 90.6% of tin powder and 1.2% of dispersing agent into a tin paste stirrer, mixing and stirring for 60 minutes, and refrigerating at the temperature of 5 ℃ to obtain the lead-free tin paste.
Table 1: component proportions of solder pastes of examples 1 to 6
Table 2: component proportions of tin powders of examples 1 to 6
Table 3: component proportions of fluxes of examples 1 to 6
The lead-free tin pastes prepared in the examples 1 to 6, the lead-free tin paste sold in the comparative example 1 and the lead-containing tin sold in the comparative example 2 are subjected to performance tests, and the test results are shown in the table 4:
table 4: test results of examples 1 to 6 and comparative examples 1 to 2
As can be seen from the test data in Table 4, compared with the commercially available lead-free and lead-containing tin pastes, the lead-free tin paste prepared by the invention has more excellent wetting property and expansion rate, can intuitively reflect that the tin paste has better activity, is beneficial to reducing the generation of pillow effect defects, and has smaller corrosivity compared with the lead-free tin paste; the lead-free solder paste comprises solder powder, soldering flux and a dispersing agent, wherein the soldering flux is formed by compounding rosin, a thixotropic agent, an active agent, a solvent and an antioxidant; the active agent is selected from DL-malic acid, citric acid, monoisopropanolamine and triisopropanolamine, the active agent is preferably the combination of organic acid DL-malic acid and organic amine monoisopropanolamine, the organic acid DL-malic acid has the advantages of higher activity, meanwhile, the corrosion is extremely low, the organic amine is used as an acidity regulator and has acid-base compounding neutralization reaction with organic acid at normal temperature, the precipitation of the active organic acid at low temperature is prevented, the activity of the soldering flux is weakened, in the continuous rising process of the reflow soldering temperature, the compound product is rapidly decomposed into organic acid and organic amine, the organic acid and the organic amine are both active agents, so that the activity of the soldering flux is improved, the oxide on the surfaces of the molten solder and the bonding pad is removed, a protective layer is formed to prevent the re-oxidation, thereby improving the wettability between the solder and the bonding pad and promoting the wettability of a welding interface to form excellent welding effect; the thixotropic agent is selected from hardened castor oil, polyamide modified hydrogenated castor oil, octadecyl stearic acid amide and oleic acid amide, preferably CRAYVALLACSF polyamide modified hydrogenated castor oil produced by Acoma corporation and polyamide modified hydrogenated castor oil, has good sag resistance and temperature resistance, can adjust the rheological property and heat resistance of the soldering flux in high-temperature reflow soldering, and ensures that the tin paste still keeps good activity at high temperature; the rosin is selected from tall oil rosin, hydrogenated rosin and disproportionated rosin which have high oxidation resistance, preferably AT04 disproportionated rosin produced by Guitian chemical company, the softening point is 80 ℃, the acid value is 160mgKOH/g, the rosin is a modified rosin obtained by eliminating conjugate double bonds which are easy to oxidize on the rosin, has high oxidation resistance, has no obvious activity under the action of a protective film AT normal temperature, but is activated AT high temperature of reflow soldering, quickly removes the oxide film on the surfaces of the solder and the parent metal in a short time, and forms a protective film for preventing metal from being re-oxidized on the surface of the solder, thereby being beneficial to inhibiting the generation of the oxide film on the surface of the solder during the heating of the reflow soldering; the antioxidant and the solvent are matched to promote the wettability of the welding interface so as to form an excellent welding effect, so that the solder paste can still keep good welding activity under continuous high-temperature baking, and the generation of pillow effect defects is reduced; in addition, the tin powder comprises 3-4% of Ag, 1.5-2% of Cu, 0.5-1.0% of Bi, 0.1-0.5 Sb and the balance of Sn, the material strength of the tin paste can be enhanced by trace Bi and Sb, and the tin paste does not contain lead and halogen, is safe to use and is environment-friendly.
Claims (7)
1. A lead-free solder paste is characterized in that: the lead-free solder paste comprises the following components in parts by weight: 84.8-90.6% of tin powder, 8.2-13.8% of soldering flux and 1.2-3.8% of dispersing agent;
the tin powder comprises the following components in parts by weight: 2.8-4.5% of Ag, 1.5-2.1% of Cu, 0.5-1.2% of Bi, 0.1-0.5% of Sb and the balance of Sn;
the soldering flux consists of the following components in parts by weight: 36.4-47.3% of rosin, 19.9-30.6% of solvent, 6.2-15.1% of thixotropic agent, 14.3-22.5% of active agent and 1.2-5.6% of antioxidant;
the active agent is composed of two or more of DL-malic acid, citric acid, isopropylamine hydrobromide, triethanolamine hydrobromide, monoisopropanolamine and triisopropanolamine, and the active agent at least comprises the combination of DL-malic acid and monoisopropanolamine;
the dispersant is selected from one or a combination of oleamide, ethylene bis stearamide and ammonium polyacryl dimethyl taurate;
the antioxidant is one or a combination of 2, 6-di-tert-butyl-p-cresol, ethoxyquinoline, 2-ethyl ether oxazole and methylbenzotriazole.
2. The lead-free solder paste according to claim 1, wherein: the rosin is any one of floating oil rosin, perhydrogenated rosin and disproportionated rosin.
3. The lead-free solder paste according to claim 1, wherein: the solvent is composed of a plurality of diethylene glycol monobutyl ether, triethylene glycol methyl ether, propylene glycol phenyl ether, diethylene glycol mono-octyl ether and tripropylene glycol butyl ether.
4. The lead-free solder paste according to claim 1, wherein: the thixotropic agent is composed of one or more of hardened castor oil, polyamide modified hydrogenated castor oil, octadecyl stearic acid amide and oleic acid amide.
5. The lead-free solder paste according to claim 1, wherein: the particle size of the tin powder is 30-60 microns.
6. A method for producing the lead-free solder paste according to any one of claims 1 to 5, characterized by comprising the steps of:
s1, weighing the components according to the weight percentage for later use;
s2, adding a solvent into a container, heating to 110-130 ℃, then adding rosin, and stirring until the rosin is completely dissolved;
s3, after the rosin is completely dissolved, keeping the temperature at 110-130 ℃, adding the thixotropic agent into a container, keeping the temperature and stirring until the thixotropic agent is completely dissolved;
s4, cooling the temperature to 50-80 ℃, adding an active agent and an antioxidant, keeping the temperature and stirring for 20-30 minutes;
s5, grinding the mixture obtained in the step S4 by a grinder to obtain soldering flux;
and S6, adding 8.2-13.8% of the soldering flux obtained in the step S5, 84.8-90.6% of tin powder and 1.2-3.8% of a dispersing agent into a tin paste stirrer, mixing and stirring for 30-60 minutes, and refrigerating at 0-5 ℃ to obtain the lead-free tin paste.
7. The method of claim 6, wherein the grinding in step S5 is performed by using a grinder at a rotation speed of 3000-5000 r/min to a particle size of less than 20 μm.
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
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| CN202110599849.5A CN113441866B (en) | 2019-03-20 | 2019-03-20 | Anti-pillow-effect lead-free tin paste and preparation method thereof |
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| JP2020116611A (en) * | 2019-01-24 | 2020-08-06 | 株式会社弘輝 | Flux and solder paste |
| CN111136402A (en) * | 2019-12-20 | 2020-05-12 | 深圳市朝日电子材料有限公司 | Enhanced composite soldering paste and preparation method thereof |
| CN111571064B (en) * | 2020-05-14 | 2021-04-02 | 深圳市唯特偶新材料股份有限公司 | Anti-splashing laser soldering paste and preparation method thereof |
| CN114367762B (en) * | 2020-06-11 | 2023-08-18 | 中山翰华锡业有限公司 | Solder alloy powder, low dielectric loss and high reliability solder paste and preparation method thereof |
| CN114346348B (en) * | 2022-01-06 | 2023-11-03 | 有研纳微新材料(北京)有限公司 | Photovoltaic cell and method for preparing grid electrode of photovoltaic cell by reflow soldering process |
| CN116117378A (en) * | 2023-03-27 | 2023-05-16 | 中山翰华锡业有限公司 | Environment-friendly low-residue easy-cleaning soldering paste and preparation method thereof |
| CN118060791A (en) * | 2024-03-07 | 2024-05-24 | 东莞市高海亮金属材料科技有限公司 | Lead-free solder paste with good fluidity and no agglomeration and preparation method thereof |
| CN118204671A (en) * | 2024-03-18 | 2024-06-18 | 东莞市高海亮金属材料科技有限公司 | Solder paste for reducing rosin residues and preparation method thereof |
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| WO2001036148A1 (en) * | 1999-11-18 | 2001-05-25 | Nippon Steel Corporation | Solder alloy, electronic member having solder ball and solder bump |
| JP2003275892A (en) * | 2002-03-20 | 2003-09-30 | Tamura Kaken Co Ltd | Lead-free solder alloy and solder paste composition |
| JP2006167802A (en) * | 2004-03-31 | 2006-06-29 | Nof Corp | Solder paste |
| CN100352596C (en) * | 2005-07-22 | 2007-12-05 | 沈阳工业大学 | Lead-free soft brazing alloy containing mixed rare earth and production thereof |
| CN101653876B (en) * | 2009-08-19 | 2012-05-02 | 浙江一远电子材料研究院 | Low-silver halogen-free soldering paste |
| WO2012127642A1 (en) * | 2011-03-23 | 2012-09-27 | 千住金属工業株式会社 | Lead-free solder alloy |
| CN102513738A (en) * | 2011-12-28 | 2012-06-27 | 东莞优诺电子焊接材料有限公司 | Continuous spot coating halogen-free solder paste and preparation method |
| WO2014053066A1 (en) * | 2012-10-04 | 2014-04-10 | Celestica International Inc. | Solder alloy for low-temperature processing |
| CN103008919B (en) * | 2012-12-13 | 2015-05-27 | 郴州金箭焊料有限公司 | Low-silver halogen-free lead-free solder paste |
| CN104175025A (en) * | 2014-04-30 | 2014-12-03 | 江苏博迁新材料有限公司 | Halogen-free soldering flux for lead-containing solder paste |
| CN104923952A (en) * | 2015-06-09 | 2015-09-23 | 广西南宁迈点装饰工程有限公司 | Lead-free halogen-free tin paste and production process thereof |
| CN106670680B (en) * | 2017-02-17 | 2018-11-23 | 广州适普电子有限公司 | A kind of anti-pillow effect scaling powder and its preparation method and application |
| CN108213766B (en) * | 2018-01-16 | 2020-04-28 | 中山翰华锡业有限公司 | Special soldering paste for aluminum product welding and preparation method and use method thereof |
| CN108465973A (en) * | 2018-06-25 | 2018-08-31 | 深圳市博士达焊锡制品有限公司 | A kind of unleaded medium temperature solder(ing) paste and preparation method thereof |
| CN108788512A (en) * | 2018-08-24 | 2018-11-13 | 东莞市仁信电子有限公司 | A kind of low voidage leadless environment-friendly solder(ing) paste of low melting point |
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| CN113441866B (en) | 2022-12-13 |
| CN113441865A (en) | 2021-09-28 |
| CN113441866A (en) | 2021-09-28 |
| CN109848603A (en) | 2019-06-07 |
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