CN111892995A - Soldering flux cleaning agent for chip packaging process - Google Patents

Abstract

The invention discloses a soldering flux cleaning agent for a chip packaging process, which comprises the following components in percentage by weight: fluoro-organic compounds: 2 to 8 percent; glycerol ether: 20 to 40 percent; n, N-dimethylacetamide: 5 to 15 percent; mercaptobenzothiazole: 1 to 5 percent; ethanol: 20 to 30 percent; the balance being water. The cleaning agent is added with a fluoro organic substance with strong electron withdrawing capability, has excellent wetting effect, and can effectively act on surfaces which are difficult to wet, such as blind holes, gaps and the like; the alcohol ether and the acetamide have good dissolving and removing capacities on organic acid, organic amine, rosin and glue substances respectively, and have good low-temperature cleaning effect and high oil removal speed; 2-mercaptobenzothiazole serving as a metal corrosion inhibitor reduces the corrosion effect of the cleaning agent on metal; the ethanol improves the quick-drying characteristic of the cleaning agent, and avoids corrosion of a bonding pad or a pin and the like caused by untimely drying.

Description

Flux cleaner for chip packaging process

technical field

The invention relates to the technical field of materials in the electronic industry, in particular to a flux cleaning agent for a chip packaging process.

Background technique

In the processing technology of electronic information products, the cleaning of SMT (surface mount technology) printed screen boards, wave ovens, reflow ovens, and PCBA (assembled circuit boards) consumes a lot of cleaning agents every year. Generally, in the process of PCB assembly and welding, in order to ensure the reliability of welding, it is necessary to use flux with high activity. These fluxes remain on the PCBA, which will corrode the circuit board and components, and reduce its surface insulation resistance, especially In the high temperature and high humidity environment, serious corrosion and leakage will occur, affecting the reliability of the whole machine. At present, the no-clean type of flux has been gradually developed and applied, but most of the flux used in the electronics industry is still the traditional type, and the components include organic acids, organic amines, rosin/glue substances, etc. Cleaning to ensure the reliability of electronic components.

At present, industrial cleaning agents at home and abroad are generally divided into three categories: solvent-based, semi-water-based, and water-based. Solvent cleaning agents mainly include halogenated hydrocarbons (chlorinated hydrocarbons, brominated hydrocarbons, fluorinated hydrocarbons), petroleum, alcohols, ethers, glycol esters, siloxanes, etc. All are mature, and most have good cleaning effect. Among them, ODS (Ozone Depleting Substances) such as Freon (CFC-113) will destroy the ozone layer and endanger the ecological environment, and have been banned. Semi-aqueous cleaning agent is a cleaning agent developed to improve the performance of solvent cleaning agents in practical applications. It is mainly composed of organic solvents (such as alcohols, terpene glycol ethers, hydrocarbons, etc.), active agents and water. (5-20%) composition. The semi-aqueous cleaning agent has high dissolving power and high cleaning cleanliness. The organic solvent it contains has good cleaning ability for organic matter, which reduces the volatility and flammability of the original flammable solvent. However, the semi-water-based cleaning technology has the following disadvantages: long process flow, high operating cost, and large amount of wastewater treatment; metal is prone to corrosion and discoloration during pure water rinsing; still contains volatile organic compounds, etc. The main components of water-based cleaning agents are surfactants, cleaning aids, corrosion inhibitors, etc., and are widely used cleaning agents in recent years. This type of cleaning agent has good compatibility, low price, safe operation, non-flammable and non-explosive, and has a large degree of freedom in cleaning and formulation. The formulation can be adjusted for different pollutants. However, the water-based cleaning agents in our country still have the following shortcomings: 1. For many viscous waxy dirt, such as rosin, glue, as well as blind holes and gaps on the workpiece, the cleaning effect of hydrophobic parts is poor, and the current water-based cleaning effect is poor. After the PCBA is cleaned with the agent, the board surface is generally prone to whitening; Ⅱ. The residues after cleaning with some water-based cleaning agents are difficult to rinse off, especially the residues in the blind holes and gaps. These residues may be harmful to subsequent processes or Influenced by the application; Ⅲ. The low temperature cleaning effect is poor, and the oil removal speed is slow, which cannot be compared with the solvent type; Ⅳ. If the metal parts are not dried in time, corrosion will occur, such as steel mesh, pads on PCBA and pins of components Parts; Ⅴ, lack of special multi-effect surfactants suitable for industrial cleaning.

In view of the above deficiencies, we have made breakthroughs in the research and development of some key technologies, and prepared a new and efficient flux cleaning agent for chip packaging technology.

SUMMARY OF THE INVENTION

Aiming at the shortcomings of the above technologies, the present invention provides a flux cleaning agent for a chip packaging process. The cleaning agent has good wettability and strong ability to remove organic substances, and can efficiently remove blind holes, gaps and general surfaces on workpieces. Residual flux and other oil stains; metal corrosion inhibitor and volatile ethanol are added at the same time, the drying speed is fast, and the corrosion of components caused by untimely drying is avoided.

In order to achieve the above-mentioned purpose, the present invention provides a kind of flux cleaning agent for chip packaging process, and its components and weight percentage are:

Fluorinated organics: 2-8%

Glyceryl ethers: 20-40%

N,N-Dimethylacetamide: 5-15%

Mercaptobenzothiazole: 1-5%

Ethanol: 20-30%

The balance is water;

Prepare a clean glass reactor and place it in an ice bath;

Add the glycerol ether and ethanol of the above-mentioned weight percentages into the reactor, start stirring, and adjust the rotating speed to 150-180rpm to make the mixing uniform;

Under stirring, N,N-dimethylacetamide, perfluorobutyl methyl ether, 2-mercaptobenzothiazole were added in sequence, and finally water was added;

After evenly dispersing, it is left to stand, sealed and protected from light and stored in a cool place to obtain a flux cleaning agent for a chip packaging process.

Wherein, the fluorinated organic compound is perfluorotripropylamine or perfluorobutyl methyl ether, and the preferred concentration is 3-5%; fluorine has strong electron-withdrawing ability, which has excellent thermal stability, unique low surface free energy and low The viscosity, but also has good wettability, as a surfactant for cleaning agents.

Among them, the preferred concentration of the glycerol ether is 25-35%; it is a good wetting agent and can effectively remove the organic acid and organic amine in the residual flux.

Wherein, the preferred concentration of the N,N-dimethylacetamide is 8-12%; it can effectively dissolve rosin and glue substances in the residual flux, and efficiently remove organic matter.

Among them, the preferred concentration of the 2-mercaptobenzothiazole is 2-3%; it contains -N-S- bonds, which can be effectively adsorbed on the metal surface, and form an insoluble complex deposition film with the metal ions at the interface, which plays a role in slowing down Erosion.

Among them, the preferred concentration of the ethanol is 25-30%; it has volatile characteristics, provides quick-drying characteristics of the cleaning agent after use, and avoids corrosion of the pads and pins of electronic components caused by untimely drying.

The beneficial effects of the present invention are: compared with the prior art, the flux cleaning agent for chip packaging process provided by the present invention has the following advantages: the cleaning agent is added with fluorinated organic substances with strong electron-absorbing ability, and has excellent It can effectively act on the surface that is not easy to wet such as blind holes and gaps; alcohol ethers and acetamides have good dissolving and removing ability to organic acids, organic amines, rosin, and glue, respectively, and have good low-temperature cleaning effect. , the oil removal speed is fast; 2-mercaptobenzothiazole as a metal corrosion inhibitor reduces the corrosion effect of the cleaning agent on the metal; ethanol improves the quick-drying characteristics of the cleaning agent, avoiding the pads or pins caused by untimely drying. corrosion at the place. It is a new and efficient flux cleaning agent for chip packaging process. The cleaning agent has good wettability and strong ability to remove organic matter, and can effectively remove blind holes, gaps and general surface residual flux and other oil stains on the workpiece; at the same time, metal corrosion inhibitor and volatile ethanol are added, and the drying speed is fast. , to avoid the corrosion of components caused by untimely drying.

Description of drawings

Figure 1 is a picture of the solder sample board before cleaning;

FIG. 2 is a diagram of a solder sample board after cleaning with a cleaning agent according to the first embodiment of the present invention.

Detailed ways

In order to express the present invention more clearly, the present invention will be further described below with reference to the accompanying drawings.

The present invention provides a flux cleaning agent for chip packaging technology, and its components and weight percentages are:

Fluorinated organics: 2-8%

Glyceryl ethers: 20-40%

N,N-Dimethylacetamide: 5-15%

Mercaptobenzothiazole: 1-5%

Ethanol: 20-30%

The balance is water; about 15-25%;

Prepare a clean glass reactor and place it in an ice bath;

Add the glycerol ether and ethanol of the above-mentioned weight percentages into the reactor, start stirring, and adjust the rotating speed to 150-180rpm to make the mixing uniform;

Under stirring, N,N-dimethylacetamide, perfluorobutyl methyl ether, 2-mercaptobenzothiazole were added in sequence, and finally water was added;

After evenly dispersing, it is left to stand, sealed and protected from light and stored in a cool place to obtain a flux cleaning agent for a chip packaging process.

In this embodiment, the fluorinated organic compound is perfluorotripropylamine or perfluorobutyl methyl ether, and the preferred concentration is 3-5%; fluorine has a strong electron-withdrawing ability, which has excellent thermal stability, unique low surface freedom Energy and lower viscosity, while also having good wetting, as a surfactant for cleaning agents.

In this embodiment, the preferred concentration of the glycerol ether is 25-35%; it is a good wetting agent and can effectively remove organic acids and organic amines in the residual flux.

In this embodiment, the preferred concentration of N,N-dimethylacetamide is 8-12%; it can effectively dissolve rosin and glue substances in the residual flux, and efficiently remove organic matter.

In this embodiment, the preferred concentration of the 2-mercaptobenzothiazole is 2-3%; it contains -N-S- bonds, which can be effectively adsorbed on the metal surface and form an insoluble complex deposition film with the metal ions at the interface , play a role in corrosion inhibition.

In this embodiment, the preferred concentration of the ethanol is 25-30%; it has volatile properties, provides quick-drying properties after the cleaning agent is used, and avoids corrosion of the pads and pins of electronic components caused by untimely drying .

The following are specific embodiments of the present invention:

Example 1:

The components of the flux cleaning agent for the chip packaging process, including by weight: 3 parts of perfluorobutyl methyl ether, 30 parts of glycerol ether, 10 parts of N,N-dimethylacetamide, 2 parts of 2-mercaptobenzothiazole, 30 parts of ethanol and 25 parts of water.

The preparation method is:

1. Prepare a clean glass reactor and place it in an ice bath;

2. Add the glycerol ether and ethanol of the above weight parts into the reaction kettle, start stirring, and adjust the rotating speed to 150-180rpm to make the mixing uniform. N,N-dimethylacetamide, perfluorobutyl methyl ether, and 2-mercaptobenzothiazole were added in sequence under stirring, and finally ultrapure water was added to make up.

3. After dispersing evenly, let it stand, seal it and keep it away from light and store it in a cool place to obtain a flux cleaning agent for the chip packaging process.

Embodiment 2:

The components of the flux cleaning agent for the chip packaging process, including by weight: 5 parts of perfluorotripropylamine, 35 parts of glycerol ether, 8 parts of N,N-dimethylacetamide, 3 parts of 2-mercaptobenzothiazole, 28 parts of ethanol and 21 parts of water.

The preparation method is:

1. Prepare a clean glass reactor and place it in an ice bath;

2. Add the glycerol ether and ethanol of the above weight parts into the reaction kettle, start stirring, and adjust the rotating speed to 150-180rpm to make the mixing uniform. N,N-dimethylacetamide, perfluorotripropylamine, and 2-mercaptobenzothiazole were added in sequence under stirring, and finally ultrapure water was added.

3. After dispersing evenly, let it stand, seal it and keep it away from light and store it in a cool place to obtain a flux cleaning agent for the chip packaging process.

It can be seen from Figure 1 and Figure 2 that after using flux soldering, there is a lot of flux and dirt remaining on the surface of the PCB sample board (Figure 1); after cleaning with the flux cleaner in Example 1, the surface becomes smooth and metal intact (Figure 2). With reference to IPC-TM-6502.3.28&2.3.25 standard, use ion chromatography analyzer & cleanliness tester to test the ion contamination of the two sample boards, the results are listed in Table 1, Table 1 is the residue of the solder sample board before and after cleaning in the present invention The test result chart; it can be seen that the content of most ions and organic acids is significantly reduced after cleaning, reaching the cleaning standard, and the next process or process can be carried out smoothly. Table 1 is as follows:

The above disclosure is only an embodiment of the present invention, but the present invention is not limited thereto, and any changes that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims (5)

1. The soldering flux cleaning agent for the chip packaging process is characterized by comprising the following components in percentage by weight:

fluoro-organic compounds: 2 to 8 percent of

Glycerol ether: 20 to 40 percent of

N, N-dimethylacetamide: 5 to 15 percent of

Mercaptobenzothiazole: 1 to 5 percent

Ethanol: 20 to 30 percent

The balance of water;

preparing a clean glass reaction kettle, and placing the glass reaction kettle in an ice bath;

adding the glycerol ether and the ethanol in percentage by weight into the reaction kettle, starting stirring, and uniformly mixing by regulating the rotation speed to 150 plus 180 rpm;

sequentially adding N, N-dimethylacetamide, perfluorobutyl methyl ether and 2-mercaptobenzothiazole under the stirring state, and finally supplementing water;

and after uniform dispersion, standing, sealing and keeping in shade for storage to obtain the soldering flux cleaning agent for the chip packaging process.

2. The flux cleaning agent for the chip packaging process according to claim 1, wherein the fluorinated organic substance is perfluorotripropylamine or perfluorobutyl methyl ether, and the concentration is preferably 3-5%; fluorine has strong electron withdrawing ability, excellent thermal stability, unique low surface free energy and low viscosity, and good wettability, and can be used as surfactant of cleaning agent.

3. The flux cleaning agent for the chip packaging process according to claim 1, wherein the preferred concentration of the glycerol ether is 25-35%; the soldering flux is a good wetting agent, and can effectively remove organic acid and organic amine in the residual soldering flux.

4. The flux cleaning agent for the chip packaging process according to claim 1, wherein the preferable concentration of the N, N-dimethylacetamide is 8-12%; can effectively dissolve the rosin and glue substances in the residual soldering flux and efficiently remove organic matters.

5. The flux cleaning agent for the chip packaging process according to claim 1, wherein the preferred concentration of the 2-mercaptobenzothiazole is 2-3%; it contains-N-S-bond, can be effectively adsorbed on the metal surface, and can form an insoluble complex deposition film with metal ions at the interface, so that the corrosion inhibition effect is achieved.

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