CN101104231A - A no-clean water-based flux that inhibits the growth of interfacial compounds in solder joints - Google Patents

Abstract

A no-cleaning water-based flux that can inhibit the growth of solder joint interface compounds, relates to a material for welding, in particular to a no-clean water-based flux that can inhibit the growth of solder joint interface compounds for microelectronic welding type flux. The invention provides a no-cleaning water-based flux that can be used effectively with lead-free solder, has bright solder joints, can hinder the growth of intermetallic compounds, has good soldering effect and interface performance, and can inhibit the growth of solder joint interface compounds. The composition and its content by mass percentage are: 0.1%-0.3% of organic reducing agent, 0.01%-1% of intermetallic compound growth inhibitor, 0.2%-3% of organic active agent, 0.1%-3% of surfactant, slow 0.1% etchant, 5% to 30% co-solvent, and the rest is water.

Description

A no-clean water-based flux that inhibits the growth of interfacial compounds in solder joints

technical field

The invention relates to a welding material, in particular to a no-cleaning water-based flux used for microelectronic welding that can inhibit the growth of solder joint interface compounds.

Background technique

With the increasingly serious problem of global environmental pollution, the European Union promulgated two decrees, "Waste of Electrical and Electronic Equipment (WEEE)" and "Regarding the Prohibition of Using Certain Hazardous Substances in Electrical and Electronic Equipment (RHOS)", starting from July 1, 2006 , a complete ban on the import of lead-containing electronic products. At present, Sn-Ag and Sn-Ag-Cu eutectic systems are mainly used in the world to replace traditional SnPb alloys, but the wettability of the new alloy system is worse than that of traditional SnPb alloys, and it is easy to be oxidized. The excessive growth of intermetallic compounds causes the mechanical properties of solder joints to decline. Using traditional flux, the soldering effect is extremely poor.

There have been some related reports on lead-free solder fluxes. The invention patent application with the publication number CN 1565791A provides a no-clean film-forming water-based flux. Contains by weight: 0.5% to 8% of water-soluble thermosetting resin, 0.5% to 5% of activator and 90% to 99% of deionized water, wherein the activator consists of surface active ingredients, organic acids and alcohols Co-solvent composition. Applied in microelectronic welding production, it can eliminate the pollution and safety problems caused by organic solvent fluxes, and can also eliminate the cleaning process, and can form a non-water-soluble film with certain adhesion on the surface of the circuit board. It plays a protective role against moisture and moisture, and effectively improves the insulation stability of electrical products. Use film-forming protection, but a large amount of organic solvent must be used for some oil-soluble polymer film-forming agents, and water-soluble polymer film-forming agents are easy to absorb moisture after welding. Part of it is just to replace the traditional rosin-type flux solvent with a high-boiling solvent to adapt to the high-temperature operation of lead-free soldering. There is not much improvement on the whole, and the soldering effect on lead-free solder is very poor. The invention patent application with the publication number CN1836825A provides a water-soluble solder flux for lead-free solder, which is composed of the following substances in weight percentage: 5.0% to 10.0% of boric acid and organic acid activator, nonionic surfactant or cationic surfactant 0.1%-1.0%, co-solvent 8.0%-20.0%, film-forming agent 0.1%-1.0%, corrosion inhibitor 0.1%-0.5%, and the rest is deionized water. The flux does not contain rosin, halide-free, environmental protection, has excellent soldering performance on lead-free solder, full solder joints, uniform spreading, low corrosion, and the residue after soldering is soluble in water. After cleaning with water, dry the copper board and test the board All of the surface insulation resistances are greater than 1.0×10 ¹¹ Ω. The Chinese patent whose publication number is CN1562554 provides a kind of no-cleaning lead-free solder flux, which is composed of the following substances in weight ratio: organic acid activator 1.0%～5.0%, improved resin 2.0%～8.0%, surfactant 0.2%~1.0%, high boiling point solvent 2.0%~13.0%, wetting agent 1.0%~6.0%, the rest is solvent: isopropanol or deionized water. With non-ionic covalently bonded bromides, post-soldering residues can be more corrosive. Most of the existing fluxes only consider the spreadability of solder joints, ignoring the compatibility of lead-free solders. After lead-free solder is soldered, intermetallic compounds grow in large quantities, resulting in a decrease in the mechanical properties of the solder joints. In the industry, nickel with a thickness of 5-7 μm is plated on the copper substrate to increase the mechanical properties of the solder joints, but this increases the cost and difficulty of the process.

Contents of the invention

The object of the present invention is to aim at the characteristics of the existing lead-free solders, to provide a kind of solder joints that can be effectively used with lead-free solders, the solder joints are bright, can hinder the growth of intermetallic compounds, have good welding effect and interface performance, and can inhibit solder joint interface compounds. No-clean water-based flux for growth.

The technical solution of the present invention is to directly start from the flux, modify the surface of the substrate through the flux, and suppress the atomic diffusion between the substrate and the solder, thereby hindering the growth of the intermetallic compound. This not only ensures good flux performance, but also improves the mechanical properties of the solder joints.

Composition of the present invention and its content by mass percentage are:

Organic reducing agent 0.1%~0.3%, intermetallic compound growth inhibitor 0.01%~1%, organic active agent 0.2%~3%, surfactant 0.1%~3%, corrosion inhibitor 0.1%, cosolvent 5%~ 30%, the remainder is water.

The organic reducing agent used in the present invention is at least one of ascorbic acid, 4-hexylresorcinol, ascorbate, L-ascorbyl palmitate, isoascorbic acid, phytic acid, tea polyphenols, vitamin E and carotene.

The intermetallic compound growth inhibitor used in the present invention is the interface film-forming agent, and the intermetallic compound growth inhibitor is at least one of oxalic acid, anthranilic acid, 8-hydroxyquinoline and quinoline-2-carboxylic acid.

The organic active agent used in the present invention does not contain halogen, and the organic active agent is composed of 50%-90% organic acid and 10%-50% organic amine according to mass percentage. The organic acid is mainly at least one of aliphatic monobasic acid, aliphatic dibasic acid, aliphatic polybasic acid, tartaric acid, salicylic acid and citric acid. The organic amine is an alcohol amine, an amide or a fatty amine, the alcohol amine can be one of monoethanolamine, diethanolamine and triethanolamine, the amide is urea, and the fatty amine is a monoamine or a diamine with a carbon chain atom number less than 12; The organic amine may also be at least one of the three types of amines.

Surfactants used in the present invention are nonionic surfactants, can be OP series surfactants, at least one in TX series surfactants, wherein it is better to cooperate with high molecular weight and low molecular weight surfactants.

The corrosion inhibitor used in the present invention is a nitrogen-containing heterocyclic compound.

The auxiliary solvent used in the present invention is an alcohol or alcohol ether with a boiling point above 140° C., which may be at least one of ethylene glycol, glycerol and ethylene glycol butyl ether.

The present invention can be prepared by the following method: in a reactor with a stirrer, first add a cosolvent and water, add an organic active agent, a surfactant, a corrosion inhibitor, an intermetallic compound growth inhibitor and a reducing agent under stirring, and then Heating to 50-70°C, stirring evenly, standing and filtering to obtain the product of the present invention.

The soldering flux prepared by this method can better meet the J-STD-004 standard in its soldering performance. After the Sn3.5Ag0.5Cu solder is soldered, it is annealed at 190°C for 120 hours. The thickness of the intermetallic compound in the interface layer is 6.5-7.5 μm, and the interface is relatively gentle, while the thickness of the intermetallic compound layer of ordinary flux is 8 ~12 μm.

Because the present invention adopts organic reducing agent, has anti-oxidation effect, therefore guaranteed the brightness of solder joint; Owing to the addition of intermetallic compound growth inhibiting agent, a layer of interfacial compound precipitation layer is formed at the solder and interface, which inhibits the solder and substrate Atomic diffusion, thus hindering the growth of intermetallic compounds; due to the addition of organic active agents, it can remove the oxide film on the surface of the copper plate; due to the addition of surfactants, the surface tension of the solder metal and the surface energy of the substrate are reduced, thus enhancing The welding effect is improved; since other fluxes are added to adjust the stability of the flux boiling during the welding process, the basic fluxing performance is guaranteed and the interface performance is improved.

Detailed ways

The present invention will be further described in detail below in conjunction with the embodiments.

Embodiment 1: Raw materials are selected ascorbic acid 0.2g, oxalic acid 0.01g, adipic acid 1g, citric acid 0.5g, urea 0.5g, OP-10 0.1g, benzotriazole 0.1g, ethylene glycol 15g, glycerol 5g, 77.6g deionized water. When preparing, first add cosolvent and deionized water into the reaction kettle with agitator, add organic active agent, surfactant, corrosion inhibitor, intermetallic compound growth inhibitor and reducing agent under stirring, and then heat to 60 ℃, stir evenly, let stand and filter to obtain flux. The halogen content of the obtained soldering flux is less than 0.01, the expansion rate is 83.1%, and the dryness and copper plate corrosion performance are both qualified. There is no special smell when soldering with this flux, and the surface of the solder joint is bright. After soldering with Sn3.5Ag0.5Cu solder, the thickness of the intermetallic compound layer after annealing at 190°C for 120 hours is 7.4 μm.

Embodiment 2: Raw materials are selected L-ascorbyl palmitate 0.1g, oxalic acid 0.7g, 8-hydroxyquinoline 0.3g, succinic acid 0.15g, triethanolamine 0.05g, T X-1002g, benzotriazole 0.1g , ethylene glycol 30g, deionized water 66.6g. During preparation, first add co-solvent and deionized water into the reaction kettle with agitator, add organic active agent, surfactant, corrosion inhibitor, intermetallic compound growth inhibitor and reducing agent under stirring, and then heat to 50 ℃, stir evenly, let stand and filter to obtain flux. After testing, the prepared flux has a density of 1.018g/L, a halogen content of <0.01, an expansion rate of 80.8%, and the dryness and corrosion performance of copper plates are all qualified. When soldering with this flux, there is no special smell, and the surface of the solder joint is bright. After soldering with Sn3.5Ag0.5Cu solder, the thickness of the intermetallic compound layer annealed at 190°C for 120 h is 7.0 μm, and the interface is gentle.

Embodiment 3: raw material selects sodium ascorbate 0.3g, oxalic acid 0.1g, anthranilic acid 0.1g, acetic acid 0.1g, citric acid 0.5g, diethanolamine 0.1g, OP-10 1g, benzotriazole 0.1g, propane Triol 5g, deionized water 84.7g. During preparation, first add co-solvent and deionized water into the reaction kettle with agitator, add organic active agent, surfactant, corrosion inhibitor, intermetallic compound growth inhibitor and reducing agent under stirring, and then heat to 50 ℃, stir evenly, let stand and filter to obtain flux. The halogen content of the prepared flux is less than 0.01, the expansion rate is 82.3%, and the dryness and copper plate corrosion performance are both qualified. There is no special smell when soldering with this flux, and the surface of the solder joint is bright. After soldering with Sn3.5Ag0.5Cu solder, the thickness of the intermetallic compound layer after annealing at 190°C for 120 hours is 7.1 μm.

Embodiment 4: raw materials select 4-hexylresorcinol 0.1g, oxalic acid 0.01g, quinoline-2-carboxylic acid 0.1g, succinic acid 1.4g, monoethanolamine 1.5g, OP-10 3g, benzotriazepam azole 0.1g, glycerin 3g, ethylene glycol butyl ether 10g, purified water 80.79g. When preparing, first add co-solvent and deionized water into the reaction kettle with agitator, add organic active agent, surfactant, corrosion inhibitor, intermetallic compound growth inhibitor and reducing agent under stirring, and then heat to 50 ℃, stir evenly, let stand and filter to obtain flux. The halogen content of the prepared flux is less than 0.01, the expansion rate is 85.3%, and the dryness and copper plate corrosion performance are both qualified. There is no special smell when soldering with this flux, and the surface of the solder joint is bright. After soldering with Sn3.5Ag0.5Cu solder, the thickness of the intermetallic compound layer after annealing at 190°C for 120 hours is 7.5 μm.

Embodiment 5: Raw materials are selected erythorbic acid 0.1g, phytic acid 0.05g, oxalic acid 0.01g, quinoline-2-carboxylic acid 0.1g, tartaric acid 1.4g, dodecylamine 1.5g, OP-4 0.5g, benzotriazepam azole 0.1g, glycerol 3g, ethylene glycol 10g, purified water 83.24g. During preparation, first add co-solvent and deionized water into the reaction kettle with agitator, add organic active agent, surfactant, corrosion inhibitor, intermetallic compound growth inhibitor and reducing agent under stirring, and then heat to 50 ℃, stir evenly, let stand and filter to obtain flux. The halogen content of the prepared soldering flux is less than 0.01, the expansion rate is 85.0%, and the dryness and copper plate corrosion performance are both qualified. There is no special smell when soldering with this flux, and the surface of the solder joint is bright. After soldering with Sn3.5Ag0.5Cu solder, the thickness of the intermetallic compound layer after annealing at 190°C for 120h is 7.2 μm.

Example 6: The raw materials are 0.1g of tea polyphenols, 0.05g of oxalic acid, 0.4g of salicylic acid, 0.8g of citric acid, 1.5g of methylamine, 0.5g of TX-100, 0.5g of TX-10, and 0.1g of benzotriazole g, glycerol 3g, ethylene glycol 10g, deionized water 83.05g. During preparation, first add co-solvent and deionized water into the reaction kettle with agitator, add organic active agent, surfactant, corrosion inhibitor, intermetallic compound growth inhibitor and reducing agent under stirring, and then heat to 70 ℃, stir evenly, let stand and filter to obtain flux. The halogen content of the prepared soldering flux is less than 0.01, the expansion rate is 82.8%, and the dryness and copper plate corrosion performance are both qualified. There is no special smell when soldering with this flux, and the surface of the solder joint is bright. After soldering with Sn3.5Ag0.5Cu solder, the thickness of the intermetallic compound layer after annealing at 190°C for 120 hours is 7.4 μm.

Embodiment 7: The raw material selection vitamin E 0.05g, carotene 0.05g, oxalic acid 0.05g, formic acid 0.3g, succinic acid 0.8g, hexamethylenediamine 1g, OP-10 1g, benzotriazole 0.1g, glycerine Alcohol 3g, ethylene glycol 10g, deionized water 83.65g. During preparation, first add co-solvent and deionized water into the reaction kettle with agitator, add organic active agent, surfactant, corrosion inhibitor, intermetallic compound growth inhibitor and reducing agent under stirring, and then heat to 50 ℃, stir evenly, let stand and filter to obtain flux. The halogen content of the prepared flux is less than 0.01, the expansion rate is 80.9%, and the dryness and copper plate corrosion performance are both qualified. There is no special smell when soldering with this flux, and the surface of the solder joint is bright. After soldering with Sn3.5Ag0.5Cu solder, the thickness of the intermetallic compound layer after annealing at 190°C for 120 hours is 7.4 μm.

Claims (10)

1. A no-cleaning water-based flux that can inhibit the growth of solder joint interface compounds is characterized in that its composition and its content by mass percentage are: Organic reducing agent 0.1%~0.3%, intermetallic compound growth inhibitor 0.01%~1%, organic active agent 0.2%~3%, surfactant 0.1%~3%, corrosion inhibitor 0.1%, cosolvent 5%~ 30%, the remainder is water. 2. A kind of no-clean water-based flux that can inhibit the growth of solder joint interface compounds as claimed in claim 1 is characterized in that the organic reducing agent is ascorbic acid, 4-hexyl resorcinol, ascorbate, L-ascorbic acid At least one of palmitate, erythorbic acid, phytic acid, tea polyphenols, vitamin E and carotene. 3. A kind of no-cleaning water-based flux that can inhibit the growth of solder joint interface compounds as claimed in claim 1 is characterized in that the intermetallic compound growth inhibitor is oxalic acid, anthranilic acid, 8-hydroxyquinoline and At least one of quinoline-2-carboxylic acids. 4. A kind of no-cleaning water-based flux that can inhibit the growth of solder joint interface compounds as claimed in claim 1 is characterized in that by mass percentage, the organic active agent consists of 50% to 90% organic acid and 10% to Composition of 50% organic amine; the organic acid is at least one of aliphatic monobasic acid, aliphatic dibasic acid, aliphatic polybasic acid, tartaric acid, salicylic acid and citric acid. 5. A kind of no-cleaning water-based flux that can inhibit the growth of solder joint interface compounds as claimed in claim 1 is characterized in that the organic amine is alcohol amine, amide or fatty amine, and the alcohol amine is selected from monoethanolamine, diethanolamine and one of triethanolamine, the amide is urea, and the aliphatic amine is a monoamine or a diamine with carbon chain atoms less than 12. 6. A no-clean water-based flux capable of inhibiting the growth of solder joint interface compounds as claimed in claim 1, characterized in that the organic amine is at least one of the three types of amines. 7. A no-clean water-based flux that can inhibit the growth of solder joint interface compounds as claimed in claim 1, characterized in that the surfactant is a nonionic surfactant selected from OP series surfactants, TX At least one of a series of surfactants. 8. A no-clean water-based flux that can inhibit the growth of solder joint interface compounds as claimed in claim 1, characterized in that the corrosion inhibitor is a nitrogen-containing heterocyclic compound. 9. A no-clean water-based flux capable of inhibiting the growth of solder joint interface compounds as claimed in claim 1, characterized in that the flux is alcohol or alcohol ether with a boiling point above 140°C. 10. A no-clean water-based flux that can inhibit the growth of solder joint interface compounds as claimed in claim 9, wherein said alcohol or alcohol ether is selected from the group consisting of ethylene glycol, glycerol and ethylene glycol at least one of ethers.