High-reliability rosin-free no-clean soldering paste, flux paste used for soldering paste and preparation method of flux paste

Abstract

The invention belongs to the technical field of electronic welding materials, and particularly relates to high-reliability rosin-free no-clean soldering paste, flux paste used for the soldering paste and a preparation method of the flux paste. The soldering paste prepared from the flux paste is good in wettability, few in residue after welding, light in color and free of cleaning; the printing performance, the demolding performance, the void resistance and the corrosion resistance are excellent, the welding spot quality can be greatly improved, and the stability of various electronic components is guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of electronic welding materials, and in particular to a high-reliability rosin-free and cleaning-free solder paste and a flux paste used therefor and a preparation method thereof. Background Art

[0002] Solder paste is a widely used welding material in the electronics industry. Its main function is to solder tiny and precise electronic components to circuit boards. In recent years, with the rapid development of electronic information technology, the load and power consumption of various electronic devices have continued to grow. High integration, small size and high power have become the development direction of various electronic devices. The corresponding high-precision welding process has put forward higher requirements on the applicability and reliability of solder paste.

[0003] Traditional solder paste often has problems such as unstable printing performance, unsatisfactory welding effect, large amount of residue, poor reliability, etc. Its flux formula, preparation process and alloy ratio will determine the performance of the final solder joint, resulting in unstable welding quality and even affecting the stability of electronic products. For example, although rosin, one of the components of the flux, plays an important role, it causes a large amount of post-welding residue, which is very likely to cause insulation aging and corrosion, and then the insulation resistance (SIR) decreases and electrochemical migration (ECM) occurs.

[0004] In addition, although the existing publicly available solder pastes have excellent environmental protection and printability, or have excellent reliability, wettability, and reflow performance, none of them are fully taken into account. At present, new electronic components, integrated circuits, etc. are developing in the direction of high frequency, high speed, multi-function, and small size. Therefore, the existing solder paste and the flux paste used therefor still need to be improved. Summary of the invention

[0005] The main purpose of the present invention is to provide a high-reliability rosin-free and clean-free solder paste and a flux paste and a preparation method thereof. The high-quality and high-reliability flux paste provided by the present invention does not contain rosin components. The solder paste prepared with the flux paste not only has good wettability, less residue after welding, light color, and no need for cleaning; but also has excellent printing performance, demoulding performance, anti-voiding performance and corrosion resistance, which can greatly improve the quality of its solder joints and ensure the stability of various electronic components.

[0006] The first aspect of the present invention provides a high-reliability rosin-free and clean-free flux paste for solder paste, wherein the flux paste does not contain rosin and comprises the following components in mass percentage: 10wt% to 15wt% of an activator, 5wt% to 10wt% of a surfactant, 35wt% to 45wt% of a solvent, 10wt% to 18wt% of a stabilizer, 10wt% to 15wt% of a thixotropic agent, 3wt% to 5wt% of a corrosion inhibitor, and 3wt% to 5wt% of a lubricant.

[0007] In some embodiments of the present invention, the active agent includes one or more combinations of stearic acid, propylenediamine phosphate, phenylsuccinic acid, 2,2-dihydroxymethylbutyric acid, p-tert-butylbenzoic acid, succinic acid, 4-methyl-2-phenylimidazole, N-phenylanthranilic acid, triisopropanolamine, 8-hydroxyquinoline, citric acid, azelaic acid, dibromosuccinic acid, and ethylenebisstearamide.

[0008] In some embodiments of the present invention, the surfactant includes one or more combinations of lauryl sulfosuccinate, disodium lauryl sulfosuccinate, monosodium sulfosuccinate, potassium monododecyl phosphate, dodecyltrimethylammonium chloride, fatty alcohol polyoxyethylene ether, and coconut acid monoethanolamide.

[0009] In some embodiments of the present invention, the solvent includes one or more combinations of isopropanol, n-butanol, hexylene glycol, rosin alcohol, tripropylene glycol butyl ether, terpineol, ethylene glycol methyl ether, diethylene glycol ethyl ether, diethylene glycol butyl ether, 2-ethyl-1,3-hexanediol, diethylene glycol hexyl ether, glycerol, propylene glycol, dibasic acid esters, diethyl adipate, butyl formate, pentyl formate, diglycidyl ether, dioctyl phthalate, tetraethylene glycol, isohexadecanol, diethylene glycol butyl ether acetate, and nitroethane mixed solvent.

[0010] In some embodiments of the present invention, the stabilizer includes one or more combinations of dibutyltin dilaurate, phosphite, and zinc stearate.

[0011] In some embodiments of the present invention, the thixotropic agent includes one or more combinations of polyamide wax and hydrogenated castor oil.

[0012] In some embodiments of the present invention, the corrosion inhibitor includes one or more combinations of boric acid, sodium nitrite, hydroquinone, catechol, 2,6-di-tert-butyl-p-cresol, benzotriazole, and ascorbic acid.

[0013] In some embodiments of the present invention, the lubricant includes one or more combinations of castor oil, erucamide, and polyacrylamide.

[0014] The second aspect of the present invention provides a method for preparing the high-reliability rosin-free and clean-free flux paste for solder paste described in the first aspect, the preparation method comprising: mixing and melting the components forming the flux paste according to the required ratio to obtain the flux paste.

[0015] In some embodiments of the present invention, the components for forming the solder paste are added in the following order: a surfactant, an activator, a thixotropic agent, a stabilizer, a corrosion inhibitor and a lubricant are sequentially added to the solvent.

[0016] In some embodiments of the present invention, each component is stirred for 3 to 5 minutes after being added, and after all components are added, they are stirred for 15 to 20 minutes.

[0017] The third aspect of the present invention provides a high-reliability rosin-free and clean-free solder paste, which comprises the following components in mass percentage: 85wt% to 90wt% of alloy powder and 10wt% to 15wt% of flux paste; the flux paste is the flux paste described in the first aspect or the flux paste prepared by the preparation method described in the second aspect.

[0018] The fourth aspect of the present invention provides a method for preparing the high-reliability rosin-free and clean-free solder paste described in the third aspect, the preparation method comprising: mixing alloy powder and flux paste in a required ratio, heating and stirring in vacuum, and obtaining the solder paste after vacuum treatment.

[0019] In some embodiments of the present invention, the stirring speed of the vacuum heating stirring is 10 rpm / min to 20 rpm / min, the stirring time is 6 min to 18 min, and the vacuum degree is -0.06 Mpa to -0.1 Mpa.

[0020] The invention provides a high-quality and high-reliability soldering paste which does not contain rosin components. The solder paste prepared with the soldering paste not only has good wettability, less residue after soldering, light color and no need for cleaning, but also has excellent printing performance, demoulding performance, anti-voiding performance and corrosion resistance, which can greatly improve the quality of its solder joints and ensure the stability of various electronic components.

[0021] The solder paste prepared in the present invention does not add rosin components, has little residue after soldering, is light in color, does not require cleaning, is completely halogen-free, and has ultra-low voids; and online test performance results such as reflow characteristics, wetting, printing, demoulding, and corrosion resistance are all very excellent.

[0022] The present invention adopts a vacuum heating and stirring method to prepare solder paste, which can not only reduce the air content in the solder paste, effectively promote the combination of the solder paste and tin powder, and prevent the powder separation phenomenon in the subsequent use project, but also effectively reduce the internal void rate, thereby reducing hidden dangers in actual use.

[0023] The solder paste prepared by the present invention is zero-halogen, environmentally friendly, and pollution-free, truly meeting the EU "RoHS" requirement for zero-halogen soldering flux, reducing the use of harmful substances and reducing pollution to the environment.

[0024] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented according to the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0026] Figure 1 The wettability, solder joint and residual condition of the solder paste prepared in Example 1;

[0027] Figure 2 This is a graph showing the anti-collapse performance of the solder paste obtained in Example 1;

[0028] Figure 3 The figure is a diagram showing the number of solder beads in the solder paste prepared in Example 1;

[0029] Figure 4 This is a demoulding performance diagram of the solder paste prepared in Example 1;

[0030] Figure 5 This is a void ratio diagram of the solder paste obtained in Example 1;

[0031] Figure 6 This is the copper plate corrosion diagram of the solder paste prepared in Example 1. DETAILED DESCRIPTION

[0032] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present invention. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of the concept of the present invention.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which the present invention belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention; the terms "including" and "having" in the specification and claims of the present invention and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0034] In the description of the embodiments of the present invention, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present invention, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0035] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present invention. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0036] In the description of the embodiments of the present invention, the term "and / or" is only a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0037] In the description of the embodiments of the present invention, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0038] In the description of the embodiments of the present invention, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances.

[0039] The invention provides a high-reliability rosin-free and cleaning-free soldering paste for solder paste. The soldering paste does not contain rosin, and comprises the following components in mass percentage: 10wt%-15wt% of an activator, 5wt%-10wt% of a surfactant, 35wt%-45wt% of a solvent, 10wt%-18wt% of a stabilizer, 10wt%-15wt% of a thixotropic agent, 3wt%-5wt% of a corrosion inhibitor, and 3wt%-5wt% of a lubricant.

[0040] In an embodiment of the present invention, a high-quality, high-reliability flux paste is first provided, which does not contain rosin components. The solder paste prepared with this flux paste not only has good wettability, less residue after soldering, light color, and no need for cleaning; but also has excellent printing performance, demoulding performance, anti-voiding performance and corrosion resistance, which can greatly improve the quality of its solder joints and ensure the stability of various electronic components.

[0041] In an embodiment of the present invention, the mass percentage of the active agent is 10wt% to 15wt%. For example, the mass percentage of the active agent can be one of 10wt%, 11wt%, 12wt%, 13wt%, 14wt%, 15wt% or any value satisfying the above range.

[0042] In an embodiment of the present invention, the active agent includes one or more combinations of stearic acid, propylenediamine phosphate, phenylsuccinic acid, 2,2-dihydroxymethylbutyric acid, p-tert-butylbenzoic acid, succinic acid, 4-methyl-2-phenylimidazole, N-phenylanthranilic acid, triisopropanolamine, 8-hydroxyquinoline, citric acid, azelaic acid, dibromosuccinic acid, and ethylenebisstearamide.

[0043] In an embodiment of the present invention, the mass percentage of the surfactant is 5wt% to 10wt%. For example, the mass percentage of the surfactant can be one of 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt% or any value satisfying the above range.

[0044] In an embodiment of the present invention, the surfactant includes one or more combinations of lauryl sulfosuccinate, disodium lauryl sulfosuccinate, monosodium sulfosuccinate, potassium monododecyl phosphate, dodecyltrimethylammonium chloride, fatty alcohol polyoxyethylene ether, and coconut acid monoethanolamide.

[0045] In an embodiment of the present invention, the mass percentage of the solvent is 35wt% to 45wt%. For example, the mass percentage of the solvent can be one of 35wt%, 36wt%, 37wt%, 38wt%, 39wt%, 40wt%, 41wt%, 42wt%, 43wt%, 44wt%, 45wt% or any value satisfying the above range.

[0046] In an embodiment of the present invention, the solvent includes one or more combinations of isopropanol, n-butanol, hexylene glycol, rosin alcohol, tripropylene glycol butyl ether, pinene alcohol, ethylene glycol methyl ether, diethylene glycol ethyl ether, diethylene glycol butyl ether, 2-ethyl-1,3-hexanediol, diethylene glycol hexyl ether, glycerol, propylene glycol, dibasic acid esters, diethyl adipate, butyl formate, pentyl formate, diglycidyl ether, dioctyl phthalate, tetraethylene glycol, isohexadecanol, diethylene glycol butyl ether acetate, and nitroethane mixed solvent.

[0047] In an embodiment of the present invention, the mass percentage of the stabilizer is 10wt% to 18wt%. For example, the mass percentage of the stabilizer can be one of 10wt%, 11wt%, 12wt%, 13wt%, 14wt%, 15wt%, 16wt%, 17wt%, 18wt% or any value satisfying the above range.

[0048] In an embodiment of the present invention, the stabilizer includes one or more combinations of dibutyltin dilaurate, phosphite, and zinc stearate.

[0049] In an embodiment of the present invention, the mass percentage of the thixotropic agent is 10wt% to 15wt%. For example, the mass percentage of the thixotropic agent can be one of 10wt%, 11wt%, 12wt%, 13wt%, 14wt%, 15wt% or any value satisfying the above range.

[0050] In an embodiment of the present invention, the thixotropic agent includes one or more combinations of polyamide wax and hydrogenated castor oil.

[0051] In an embodiment of the present invention, the mass percentage of the corrosion inhibitor is 3wt% to 5wt%. For example, the mass percentage of the corrosion inhibitor can be one of 3wt%, 4wt%, 5wt% or any value satisfying the above range.

[0052] In an embodiment of the present invention, the corrosion inhibitor includes one or more combinations of boric acid, sodium nitrite, hydroquinone, catechol, 2,6-di-tert-butyl-p-cresol, benzotriazole, and ascorbic acid.

[0053] In an embodiment of the present invention, the mass percentage of the lubricant is 3wt% to 5wt%. For example, the mass percentage of the lubricant can be one of 3wt%, 4wt%, 5wt% or any value satisfying the above range.

[0054] In an embodiment of the present invention, the lubricant includes one or more combinations of castor oil, erucamide, and polyacrylamide.

[0055] The present invention also provides a method for preparing a highly reliable rosin-free and clean-free solder paste for solder paste, the key of which is to mix and melt the components forming the solder paste according to a required ratio to obtain the solder paste.

[0056] The method for preparing the high-reliability rosin-free and cleaning-free soldering paste for solder paste of the present invention is carried out according to the following steps.

[0057] S1: First use a balance to accurately weigh the mass of each component according to the ratio.

[0058] S2: First, add the solvent into the reaction kettle, and then add the surfactant, active agent, thixotropic agent, stabilizer, corrosion inhibitor and lubricant respectively. After adding each component, stir at 80℃~100℃ for 3min~5min. After all components are added, stir for 15min~20min to obtain the solder paste.

[0059] It is worth mentioning that the prepared solder paste can be finely ground and left for 24 hours before use.

[0060] In an embodiment of the present invention, the stirring time after each component is added can be one of 3 min, 4 min, 5 min or any value within the above range. The stirring time after all components are added can be one of 15 min, 16 min, 17 min, 18 min, 19 min, 20 min or any value within the above range. The stirring temperature can be one of 80°C, 85°C, 90°C, 95°C, 100°C or any value within the above range.

[0061] The present invention also provides a high-reliability rosin-free and clean-free solder paste, which comprises the following components in mass percentage: 85wt% to 90wt% of alloy powder and 10wt% to 15wt% of flux paste; the flux paste is the above-mentioned flux paste or the flux paste prepared by the above-mentioned preparation method.

[0062] In the embodiment of the present invention, the solder paste provided by the present invention is a zero-halogen solder paste, which is environmentally friendly and pollution-free, truly meets the EU "RoHS" requirement for zero-halogen soldering flux, reduces the use of harmful substances, and can reduce pollution to the environment. In addition, the solder paste does not add rosin components, has little residue after soldering, is light in color, does not require cleaning, is completely halogen-free, and has ultra-low voids; at the same time, the online test performance results such as reflow characteristics, wetting, printing, demoulding and corrosion resistance are all very excellent.

[0063] In an embodiment of the present invention, the alloy powder includes but is not limited to Sn96.5Ag3Cu0.5 powder.

[0064] In an embodiment of the present invention, the mass percentage of the alloy powder is 85wt% to 90wt%. For example, the mass percentage of the alloy powder can be one of 85wt%, 86wt%, 87wt%, 88wt%, 89wt%, 90wt% or any value satisfying the above range.

[0065] In an embodiment of the present invention, the mass percentage of the soldering solder paste is 10wt% to 15wt%. For example, the mass percentage of the soldering solder paste can be one of 10wt%, 11wt%, 12wt%, 13wt%, 14wt%, 15wt% or any value satisfying the above range.

[0066] The present invention also provides a method for preparing a highly reliable rosin-free and clean-free solder paste. The key lies in mixing alloy powder and flux paste according to a required ratio, heating and stirring in a vacuum, and obtaining the solder paste after vacuum treatment. The obtained solder paste has high reliability and better welding effect.

[0067] The preparation method of the high-reliability rosin-free and clean-free solder paste of the present invention is carried out according to the following steps.

[0068] Step 1) Weigh the alloy powder and solder paste according to the required ratio and then heat and stir them in a vacuum. The heating temperature is 30°C to 40°C and the vacuum degree is within the range of -0.06Mpa to -0.1Mpa to ensure a good mixing effect and improve its uniformity and stability.

[0069] In the solder paste preparation method of the present invention, vacuum heating and stirring are adopted, which can not only reduce the air content in the solder paste, but also effectively promote the combination of the solder paste and the tin powder, prevent the powder separation phenomenon in the subsequent use process, and effectively reduce the void rate.

[0070] In an embodiment of the present invention, the heating temperature of vacuum heating and stirring can be one of 30°C, 35°C, 40°C or any value satisfying the above range. The vacuum degree can be one of -0.06Mpa, -0.07Mpa, -0.08Mpa, -0.09Mpa, -0.1Mpa or any value satisfying the above range.

[0071] In an embodiment of the present invention, the stirring speed of vacuum heating stirring is 10rpm / min~20rpm / min, and the stirring time is 6min~18min. Exemplarily, the stirring speed can be one of 10rpm / min, 11rpm / min, 12rpm / min, 13rpm / min, 14rpm / min, 15rpm / min, 16rpm / min, 17rpm / min, 18rpm / min, 19rpm / min, 20rpm / min or any numerical value satisfying the above range value. The stirring time can be one of 6min, 7min, 8min, 9min, 10min, 11min, 12min, 13min, 14min, 15min, 16min, 17min, 18min or any numerical value satisfying the above range value.

[0072] Step 2) The solder paste obtained after mixing is vacuumed to remove internal bubbles to prepare the above-mentioned solder paste.

[0073] Unless otherwise defined, the technical terms used in the following examples have the same meanings as those generally understood by those skilled in the art to which the present invention belongs. The experimental reagents used in the following examples, unless otherwise specified, are all conventional biochemical reagents; the raw materials, instruments and equipment used in the following examples, etc., can all be purchased on the market or can be obtained by existing methods; the amounts of the experimental reagents, unless otherwise specified, are the amounts of reagents used in conventional experimental operations; the experimental methods, unless otherwise specified, are all conventional methods.

[0074] Example 1

[0075] A high-reliability rosin-free and clean-free solder paste comprises the following components by mass percentage: 88.5% Sn96.5Ag3Cu0.5 powder and 11.5wt% solder paste. The solder paste comprises the following components by mass percentage: 10% azelaic acid, 10% dodecyltrimethylammonium chloride, 45% diethylene glycol ethyl ether, 12% dibutyltin dilaurate, 14% hydrogenated castor oil, 4% 2,6-di-tert-butyl-p-cresol, and 5% polyacrylamide.

[0076] Preparation method of solder paste:

[0077] S1: First use a balance to accurately weigh the mass of each component according to the ratio.

[0078] S2: First, add diethylene glycol ethyl ether into the reactor, and then add dodecyl trimethyl ammonium chloride, azelaic acid, hydrogenated castor oil, dibutyl tin dilaurate, 2,6-di-tert-butyl-p-cresol and polyacrylamide into the diethylene glycol ethyl ether in sequence. After each component is added, stir at 90°C for 4 minutes, and finally stir for 20 minutes to obtain the solder paste.

[0079] Preparation method of high-reliability rosin-free and no-clean solder paste:

[0080] Step 1) alloy powder and solder paste are weighed according to the required ratio, and then vacuum heated and stirred at 40°C and a vacuum degree of -0.1Mpa. The stirring speed is 15rpm / min and the stirring time is 10min.

[0081] Step 2) The solder paste obtained after mixing is vacuumed to remove internal bubbles again to prepare solder paste.

[0082] Example 2

[0083] The remaining operations are the same as those in Example 1, except that the vacuum heating stirring speed is 20 rpm / min and the stirring time is 6 min in the preparation of the high-reliability rosin-free and clean-free solder paste.

[0084] Example 3

[0085] The remaining operations are the same as those in Example 1, except that the vacuum heating stirring speed is 10 rpm / min and the stirring time is 18 min in the preparation of the high-reliability rosin-free and clean-free solder paste.

[0086] Comparative Example 1

[0087] The remaining operations are the same as those in Example 1, except that the soldering solder paste includes the following components in percentage by mass: 15% azelaic acid, 8% dodecyltrimethylammonium chloride, 35% diethylene glycol ethyl ether, 18% dibutyltin dilaurate, 10% hydrogenated castor oil, 3% 2,6-di-tert-butyl-p-cresol, 3% polyacrylamide, and 8% hydrogenated rosin.

[0088] Comparative Example 2

[0089] The remaining operations are the same as those in Example 1, except that the soldering paste includes the following components in percentage by mass: 13% azelaic acid, 5% dodecyltrimethylammonium chloride, 40% diethylene glycol ethyl ether, 10% dibutyltin dilaurate, 13% hydrogenated castor oil, 5% 2,6-di-tert-butyl-p-cresol, 4% polyacrylamide, and 10% hydrogenated rosin.

[0090] Comparative Example 3

[0091] The remaining operations are the same as those in Example 1, except that vacuum heating stirring is not used in the preparation method of the solder paste, and a conventional room temperature stirring method is specifically used, with a stirring speed of 15 rpm / min and a stirring time of 10 min.

[0092] Comparative Example 4

[0093] The remaining operations are the same as those in Comparative Example 1, except that vacuum heating stirring is not used in the preparation method of the solder paste, and a conventional room temperature stirring method is used, with a stirring speed of 15 rpm / min and a stirring time of 10 min.

[0094] Comparative Example 5

[0095] The remaining operations are the same as those in Comparative Example 2, except that vacuum heating stirring is not used in the preparation method of the solder paste, and a conventional room temperature stirring method is used, with a stirring speed of 15 rpm / min and a stirring time of 10 min.

[0096] The composition and stirring method of the flux paste and solder paste in Example and Comparative Example 1 are detailed in Table 1.

[0097] Table 1 Summary of the composition and stirring methods of flux paste and solder paste in the embodiments and comparative examples

[0098]

[0099] Performance Testing

[0100] Test standard:

[0101] Viscosity: Tested using IPC-TM-650 (2.4.34.3).

[0102] Collapse resistance: tested using IPC-TM-650 (2.4.35).

[0103] Wetting: Tested using IPC-TM-650.(2.4.45).

[0104] Solder beads: Tested using T5-T6: IPC-TM-650.(2.4.43).

[0105] Copper plate corrosion: tested using IPC-TM-650 (2.6.15C: 2004).

[0106] Table 2 Summary of performance tests of solder pastes obtained in the embodiments and comparative examples

[0107]

[0108] Combination Figure 1-6 As can be seen from Table 2, the solder paste in Examples 1-3 is unique in that no rosin is added and it is prepared by a vacuum heating and stirring process. The combination of the two not only significantly reduces the post-weld residue and lightens the color, achieving the convenience of no-cleaning, but also has excellent online test performance such as reflow characteristics, wettability, printability, demoulding, copper plate corrosion, and void rate, and the solder paste is completely halogen-free, meeting current environmental protection requirements. In contrast, although Comparative Examples 1-2 also use vacuum heating and stirring technology, due to the replacement of part of the solvent with rosin in different proportions, this change leads to a significant increase in post-weld residue, and it is widely spread above and around the solder joints. At the same time, the void rate and the number of tin beads also increase to a certain extent.

[0109] On the other hand, Comparative Example 3 omits the key step of vacuum heating and stirring on the basis of Example 1, and the prepared solder paste shows a certain amount of residue after soldering. In addition, compared with the examples, the void ratio of Comparative Examples 1-5 increases, which further confirms the positive role of vacuum heating and stirring process in reducing the void ratio.

[0110] In summary, the solder paste provided in Examples 1-3 not only performs well in terms of environmental protection and convenience, but also reaches a high level in various performance indicators. The solder paste of the present invention is mainly used in 5G electronic products and surface SMT assembly processes. At present, almost all circuit boards of electronic and electrical products use SMT processes, and the market application is very extensive. The zero-halogen solder paste prepared by the present invention achieves the requirement of zero-halogen flux; and no rosin component is added, with less residue after welding, light color, no cleaning, and ultra-low voids; and the online test performance results such as reflow characteristics, wetting, printing, demolding and corrosion resistance are all very excellent.

[0111] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention. In particular, as long as there is no structural conflict, the various technical features mentioned in each embodiment can be combined in any way. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A highly reliable rosin-free, no-clean soldering paste for solder paste, characterized in that: The soldering solder paste does not contain rosin, and the soldering solder paste includes the following components in mass percentage: 10wt% to 15wt% of active agent, 5wt% to 10wt% of surfactant, 35wt% to 45wt% of solvent, 10wt% to 18wt% of stabilizer, 10wt% to 15wt% of thixotropic agent, 3wt% to 5wt% of corrosion inhibitor, and 3wt% to 5wt% of lubricant.

2. The highly reliable rosin-free and clean-free soldering paste for solder paste according to claim 1, characterized in that: The active agent includes one or more combinations of stearic acid, propylene diamine phosphate, phenylsuccinic acid, 2,2-dihydroxymethylbutyric acid, p-tert-butylbenzoic acid, succinic acid, 4-methyl-2-phenylimidazole, N-phenylanthranilic acid, triisopropanolamine, 8-hydroxyquinoline, citric acid, azelaic acid, dibromosuccinic acid, and ethylenebisstearamide.

3. The highly reliable rosin-free and clean-free soldering paste for solder paste according to claim 1, characterized in that: The surfactant includes one or more combinations of lauryl sulfosuccinate monoester disodium, acid monoethanolamide sulfosuccinate monoester disodium, monododecyl phosphate potassium, dodecyl trimethyl ammonium chloride, fatty alcohol polyoxyethylene ether, and coconut acid monoethanolamide.

4. The highly reliable rosin-free and no-cleaning soldering paste for solder paste according to claim 1, characterized in that: The solvent includes one or more combinations of isopropanol, n-butanol, hexylene glycol, rosin alcohol, tripropylene glycol butyl ether, terpineol, ethylene glycol methyl ether, diethylene glycol ethyl ether, diethylene glycol butyl ether, 2-ethyl-1,3-hexanediol, diethylene glycol hexyl ether, glycerol, propylene glycol, dibasic acid esters, diethyl adipate, butyl formate, pentyl formate, diglycidyl ether, dioctyl phthalate, tetraethylene glycol, isohexadecanol, diethylene glycol butyl ether acetate, and nitroethane mixed solvent.

5. The highly reliable rosin-free and no-cleaning soldering paste for solder paste according to claim 1, characterized in that: The stabilizer includes one or more combinations of dibutyltin dilaurate, phosphite, and zinc stearate; Preferably, the thixotropic agent includes one or more combinations of polyamide wax and hydrogenated castor oil.

6. The highly reliable rosin-free and clean-free soldering paste for solder paste according to claim 1, characterized in that: The corrosion inhibitor includes one or more combinations of boric acid, sodium nitrite, hydroquinone, catechol, 2,6-di-tert-butyl-p-cresol, benzotriazole, and ascorbic acid; Preferably, the lubricant comprises one or more combinations of castor oil, erucamide and polyacrylamide.

7. A method for preparing a highly reliable rosin-free and clean-free soldering flux paste for solder paste according to any one of claims 1 to 6, characterized in that: The preparation method comprises: The components forming the soldering paste are mixed and melted according to a required ratio to obtain the soldering paste.

8. The preparation method according to claim 7, characterized in that: The components for forming the solder paste are added in the following order: a surfactant, an activator, a thixotropic agent, a stabilizer, a corrosion inhibitor and a lubricant are sequentially added to the solvent; Preferably, each component is stirred for 3 to 5 minutes after being added, and the mixture is stirred for 15 to 20 minutes after all components are added.

9. A high-reliability rosin-free, no-clean solder paste, characterized in that: The solder paste comprises the following components in percentage by mass: Alloy powder 85wt%~90wt%, solder paste 10wt%~15wt%; The soldering solder paste is the soldering solder paste described in any one of claims 1-6 or the soldering solder paste prepared by the preparation method described in any one of claims 7-8.

10. A method for preparing the high-reliability rosin-free and clean-free solder paste according to claim 9, characterized in that: The preparation method comprises: The alloy powder and the solder paste are mixed in a required ratio, and then heated and stirred in a vacuum, and then vacuumed to obtain the solder paste; Preferably, the stirring speed of the vacuum heating stirring is 10 rpm / min to 20 rpm / min, the stirring time is 6 min to 18 min, and the vacuum degree is -0.06 Mpa to -0.1 Mpa.

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