A solder paste for reducing rosin residue and its preparation method

Abstract

The present invention relates to the technical field of solder pastes, and particularly to a solder paste for reducing rosin residue and a preparation method thereof. The solder paste comprises the following components by mass fraction: 89.1 - 89.5% of tin powder and 10.5 - 10.9% of flux. The flux comprises the following components by weight: 10 - 40 parts of hydrogenated rosin alcohol, 0.4 - 1 part of catalyst, 80 - 200 parts of high-boiling organic solvent, 2 - 8 parts of organic acid, 12 - 20 parts of thixotropic agent, and 0.5 - 4 parts of surfactant. The solder paste of the present invention is prepared by the following method: adding each component of the flux into a stirring barrel for mixing and stirring, and then adding tin powder and stirring evenly to obtain the target product. Compared with the prior art, by reducing the amount of flux in the solder paste and reducing the amount of hydrogenated rosin alcohol in the flux, the solder paste prepared by the present invention has significantly less rosin residue at the solder joints (reduced by 66.9% - 74.8%) compared with the traditional solder paste after welding.

Description

Technical Field

[0001] The present invention relates to the technical field of solder pastes, and particularly to a solder paste for reducing rosin residue and a preparation method thereof. Background Art

[0002] In the prior art, the mass ratio of the flux in the solder paste is 12.2%, and the remaining components are metal tin powder. The components of the flux mainly include rosin, solvent, organic acid, etc. The amount of flux residue mainly depends on the proportion of rosin, because during the welding process, other substances will volatilize while rosin will not. The proportion of rosin residue at the solder joints of the existing solder paste is large, and there are the following four harms of excessive rosin residue:

[0003] 1) Rosin residue will cause low insulation impedance and malfunction of IC chips;

[0004] 2) When rosin residue enters the inside of switch components, it will affect the device function;

[0005] 3) When rosin residue enters the inside of LED lamp beads, it will reduce the luminous intensity;

[0006] 4) Rosin residue splashing onto the gold finger pads will affect the conduction function.

[0007] Regarding the problem of rosin residue in solder paste, there is an urgent need for improvement in the fields of GPS navigation, electric meters, automobiles, and 3C products. Summary of the Invention

[0008] In order to overcome the problem of excessive rosin residue in the solder paste of the prior art, the present invention provides a solder paste for reducing rosin residue and its flux.

[0009] The object of the present invention is achieved by the following technical solutions:

[0010] One of the technical solutions of the present invention provides a solder paste for reducing rosin residue, and the solder paste comprises the following components in mass fractions:

[0011] Tin powder 89.1 - 89.5%

[0012] Flux 10.5 - 10.9%.

[0013] Further, the flux comprises the following components in parts by weight:

[0014]

[0015]

[0016] Still further, the catalyst comprises one or both of bismuth hydroxide or bismuth oxide.

[0017] Further, the hydrogenated rosin alcohol includes one or more of AX-E hydrogenated rosin alcohol, RHR101 hydrogenated rosin alcohol, or KE604 hydrogenated rosin alcohol.

[0018] Further, the high-boiling organic solvent is an alcohol ether solvent, and the alcohol ether solvent includes one or two of diethylene glycol monoethyl ether or tripropylene glycol butyl ether.

[0019] Further, the organic acid is a dibasic acid, and the dibasic acid includes one or more of sebacic acid, succinic acid, malonic acid, or succinic anhydride.

[0020] Further, the thixotropic agent includes one or two of polyamide wax powder or hydrogenated castor oil.

[0021] Further, the surfactant includes one or more of 3M fluorosurfactant (FC4432), dodecylphenol polyoxyethylene ether (OP-10), or fatty alcohol polyoxyethylene ether (AEO-9).

[0022] The second technical solution of the present invention provides a method for preparing the above solder paste, and the method includes the following steps:

[0023] Add each component of the flux into a stirring barrel for mixing and stirring, and then add solder powder and stir evenly to obtain the target product.

[0024] Further, the temperature for stirring and mixing the solder powder and the flux is 160 - 180°C.

[0025] Compared with the prior art, in the preparation process of the solder paste of the present invention, the amount of the flux in the solder paste is reduced, and the amount of hydrogenated rosin alcohol in the flux is reduced, thereby reducing the rosin residue amount at the solder joint of the solder paste.

[0026] The hydrogenated rosin alcohol in the flux is used to adjust the viscosity. When the amount of hydrogenated rosin alcohol is reduced, the viscosity of the solder paste will decrease. The present invention ensures that the viscosity of the final product solder paste meets the standard through the following two aspects:

[0027] 1) The present invention adds a catalyst, and the role of the catalyst is to change the molecular structure and crystal arrangement inside the solder paste, making the material structure denser, so as to achieve the purpose of increasing the viscosity;

[0028] 2) Change the temperature of the solder paste preparation process. For example, the viscosity of the solder paste prepared at 130°C is 130 Pa·s. When the temperature is increased to 180°C, the viscosity of the solder paste can be increased to 200 Pa·s.

[0029] The beneficial effects of the present invention are as follows:

[0030] 1) By reducing the amount of flux in the solder paste (reduced to 10.5% - 10.9%) and decreasing the amount of hydrogenated rosin alcohol in the flux, the solder paste prepared has significantly less rosin residue at the solder joints (reduced by 66.9% - 74.8%) compared with the traditional solder paste after soldering.

[0031] 2) With the proportion of hydrogenated rosin alcohol in the solder paste of the present invention decreased, the cost of preparing the solder paste can be reduced by 12 - 15% (the raw material price of hydrogenated rosin alcohol is relatively high, and reducing the amount of hydrogenated rosin alcohol is beneficial to cost reduction). At the same time, the temperature is increased during the preparation process of the solder paste of the present invention, and a catalyst is added, thus avoiding the negative impact of the decreased viscosity caused by the reduced proportion of hydrogenated rosin alcohol. Detailed implementation mode

[0032] In the following examples, if there is no specially described raw material or treatment technology, it indicates that the conventional commercially available raw material products or conventional treatment technologies in the field are adopted.

[0033] Example 1

[0034] This example provides a solder paste for reducing rosin residue and its preparation method. The solder paste is composed of the following components by mass fraction: 89.1% tin powder, 10.9% flux; the flux is composed of the following components by weight: 10 parts of AX - E hydrogenated rosin alcohol, 0.4 part of bismuth hydroxide, 80 parts of diethylene glycol monoethyl ether, 2 parts of sebacic acid, 12 parts of polyamide wax powder, 0.5 part of FC4432. The tin powder and each component of the above flux are mixed evenly at 160 °C to prepare the solder paste.

[0035] Example 2

[0036] This example provides a solder paste for reducing rosin residue and its preparation method. The solder paste is composed of the following components by mass fraction: 89.5% tin powder, 10.5% flux; the flux is composed of the following components by weight: 40 parts of RHR101 hydrogenated rosin alcohol, 1 part of bismuth oxide, 200 parts of tripropylene glycol butyl ether, 8 parts of succinic acid, 20 parts of hydrogenated castor oil, 4 parts of OP - 10. The tin powder and each component of the above flux are mixed evenly at 180 °C to prepare the solder paste.

[0037] Example 3

[0038] This example provides a solder paste for reducing rosin residue and its preparation method. The solder paste is composed of the following components by mass fraction: 89.3% tin powder, 10.7% flux; the flux is composed of the following components by weight: 30 parts of KE604 hydrogenated rosin alcohol, 0.7 part of bismuth oxide, 140 parts of tripropylene glycol butyl ether, 5 parts of malonic acid, 16 parts of hydrogenated castor oil, 3 parts of AEO - 9. The tin powder and each component of the above flux are mixed evenly at 170 °C to prepare the solder paste.

[0039] Example 4

[0040] This example provides a solder paste for reducing rosin residue and a preparation method thereof. The solder paste is composed of the following components by mass fraction: 89.2% tin powder and 10.8% flux; the flux is composed of the following components by weight: 10 parts of KE604 hydrogenated rosin alcohol, 10 parts of AX-E hydrogenated rosin alcohol, 0.3 part of bismuth hydroxide, 0.3 part of bismuth oxide, 50 parts of tripropylene glycol butyl ether, 50 parts of diethylene glycol monoethyl ether, 2 parts of succinic anhydride, 2 parts of sebacic acid, 1 part of succinic acid, 8 parts of hydrogenated castor oil, 8 parts of polyamide wax powder, 1 part of FC4432, 1 part of OP-10, and 1 part of AEO-9. The tin powder and each component of the above flux are mixed evenly at 170 °C to prepare the solder paste.

[0041] Comparative Example 1

[0042] This comparative example provides a traditional solder paste and a preparation method thereof. The solder paste is composed of the following components by mass fraction: 87.8% tin powder and 12.2% flux; the flux is composed of the following components by weight: 10 parts of AX-E hydrogenated rosin alcohol, 80 parts of diethylene glycol monoethyl ether, 2 parts of sebacic acid, 12 parts of polyamide wax powder, and 0.5 part of FC4432. The tin powder and each component of the above flux are mixed evenly at 130 °C to prepare the solder paste.

[0043] The solder pastes prepared in the above Examples 1-4 and Comparative Example 1 are used for welding. After welding, the percentage of rosin residue at the solder joints (the rosin residue in Comparative Example 1 is 100%) is shown in Table 1 below:

[0044] Table 1

[0045]

[0046] The above examples are the preferred implementation schemes of the present invention. In addition, the present invention can also be implemented in other ways. Any obvious substitution without departing from the concept of the present invention is within the protection scope of the present invention.

Claims

1. A solder paste with reduced rosin residue, characterized in that: It is composed of the following components in mass fraction: Tin powder 89.1~89.5% Flux 10.5~10.9%; The soldering flux comprises the following components in parts by weight: 10-40 parts of hydrogenated rosin alcohol Catalyst 0.4-1 part 80-200 parts of high boiling point organic solvent 2-8 parts of organic acid Thixotropic agent 12-20 parts Surfactant 0.5-4 parts The catalyst includes one or both of bismuth hydroxide and bismuth oxide; The high boiling point organic solvent is an alcohol ether solvent, and the alcohol ether solvent includes one or both of diethylene glycol monoethyl ether and tripropylene glycol butyl ether; The surfactant includes one or more of FC4432, OP-10 or AEO-9; The hydrogenated rosin alcohol includes one or more of AX-E hydrogenated rosin alcohol, RHR101 hydrogenated rosin alcohol or KE604 hydrogenated rosin alcohol; The organic acid is a dibasic acid, and the dibasic acid includes one or more of sebacic acid, succinic acid, malonic acid or succinic anhydride; The thixotropic agent includes one or both of polyamide wax powder and hydrogenated castor oil; The preparation method of the solder paste comprises the following steps: Add the components of the flux into a stirring barrel and mix them, then add tin powder and stir evenly. The stirring and mixing temperature is 160-180°C to obtain the target product. When the prepared solder paste is used, the rosin residue at the solder joint is 25.2-33.1%, and the viscosity of the solder paste is 129.1-131.5 Pa·s.

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