Water-based flux cleaning agent for integration

Abstract

The invention discloses a water-based flux cleaning agent for integration, and belongs to the field of semiconductor cleaning agents. The water-based flux cleaning agent is prepared from the following raw materials in percentage by weight: 30-50% of alcohol ether solvent, 1-5% of organic amine, 3-5% of gemini imidazoline corrosion inhibitor and 40-70% of deionized water, wherein the sum of the weight percentages of the raw materials is 100%. According to the water-based flux cleaning agent, the imidazoline corrosion inhibitor is adopted, so that a remarkable cleaning effect on flux residues, soldering paste and fine particles on a semiconductor electronic device is achieved, meanwhile, the brightness of welding spots can be maintained, the surface insulation performance is good, the metal surface of an IPM module can be effectively prevented from being oxidized, and the service life of the IPM module is prolonged. The cleaning agent is especially suitable for cleaning pollutants in the welding process of semiconductor chips, chip type capacitors and circuit substrates.

Description

Technical Field

[0001] The invention belongs to the field of semiconductor cleaning agents, and in particular relates to a water-based soldering flux cleaning agent for integration. Background Art

[0002] The core of the Intelligent Power Module (IPM) is a power electronic device, which usually uses IGBT (insulated gate bipolar transistor) as a power switch and integrates drive circuits and protection circuits, making it easier to use in power electronic equipment. It is widely used in the electronics field for its small size, low power, strong anti-interference ability, and comprehensive protection functions. It is the core component of frequency conversion technology, ranging from frequency conversion home appliances to rail transportation. IPM consists of DBC (copper-clad ceramic substrate), PCB, LF lead frame, and IGBT chip. During the PIM processing process, welding will be performed on the DBC and PCB substrates. After welding, there will be different degrees of flux residue on the surface. The residue contains organic acids and ions, etc. Among them, organic acids will corrode the circuit board, and the presence of ions may cause short circuits and cause product failure. There are many types of contaminants on the circuit board, which can be summarized into two categories: ionic and non-ionic. When ionic pollutants come into contact with moisture in the environment, they undergo electrochemical migration after power is turned on, forming dendritic structures, resulting in low-resistance paths and damaging the electrical properties of the circuit board. They mainly come from processes such as electroplating, wave soldering, reflow soldering and chemical cleaning, including ethanol, aminoethanol and human sweat; non-ionic pollutants can penetrate the insulating layer of the circuit board and grow dendrites under the surface of the substrate. In addition to ionic and non-ionic pollutants, there are also granular pollutants, such as solder balls, floating points in the solder tank, dust, and dirt. These pollutants can lead to reduced solder joint quality, sharp solder joints during welding, pores, short circuits and many other undesirable phenomena.

[0003] At present, the most common cleaning agents in the precision electronics cleaning industry are solvent-based cleaning agents and water-based cleaning agents. Solvent-based cleaning agents have disadvantages such as being flammable and explosive, highly toxic, and poorly environmentally friendly, and these disadvantages require careful consideration when selecting and using them. If employees operate them improperly, they can easily cause safety hazards. The biggest problem with water-based cleaning agents is that they do not thoroughly clean flux, rosin, and particulate pollutants, and their cleaning efficiency is low, which cannot meet the actual use needs of the production line. In addition, the cleaned product is easily oxidized in a short period of time, causing discoloration on the substrate surface and corrosion of components or circuits. Summary of the invention

[0004] The purpose of the present invention is to achieve a significant cleaning effect on flux, solder paste and fine particles on semiconductor electronic devices, while maintaining the brightness of solder joints and effectively preventing oxidation of the metal surface of IPM modules, and to provide an integrated water-based flux cleaning agent.

[0005] In order to achieve the above object, the present invention adopts the following technical solution: A semi-aqueous solder flux cleaning agent for IPM packaging, the raw materials used and the weight percentage of each raw material are as follows: Alcohol ether solvent 30-50%; Organic amine 1-5%; Gemini imidazoline corrosion inhibitor 3-5%; Deionized water 40-70%; The sum of the above weight percentages is 100%.

[0006] Furthermore, the raw materials used include, by weight percentage: 40-45% alcohol ether solvent, 3-5% organic amine, 3-5% gemini imidazoline corrosion inhibitor, and 47-50% deionized water, and the sum of the above weight percentages is 100%.

[0007] Furthermore, the raw materials used include, by weight percentage: 45% propylene glycol butyl ether, 5% hexadecylamine, 3% gemini imidazoline corrosion inhibitor, and 47% deionized water.

[0008] Further, the alcohol ether solvent is at least one of propylene glycol methyl ether, propylene glycol butyl ether, ethylene glycol butyl ether, dipropylene glycol propyl ether, diethylene glycol methyl ether, diethylene glycol ethyl ether, ethylene glycol tert-butyl ether, triethylene glycol ethyl ether, triethylene glycol butyl ether, tripropylene glycol methyl ether, tripropylene glycol ethyl ether and dipropylene glycol dimethyl ether. Preferably, propylene glycol butyl ether is used.

[0009] Furthermore, the organic amine is any one of ethylenediamine, ethanolamine, tri-n-butylamine, methyldiethanolamine, alkyl alcoholamine, triethanolamine, N,N-dimethylacetamide, N,N-dimethylethanolamine, hexadecylamine, octadecylamine, and isopropylamine, preferably hexadecylamine.

[0010] Furthermore, the chemical structural formula of the gemini imidazoline corrosion inhibitor is: .

[0011] Furthermore, the resistivity of the deionized water at 25° C. is not less than 18 MΩ·cm.

[0012] The IPM module will be tested for power-on in the back-end process, which will cause its metal surface to be charged. The present invention adds a gemini imidazoline corrosion inhibitor to a water-based flux cleaning agent, and its molecular structure contains two five-membered rings, which can be better adsorbed on the surface of metal materials, and the hydroxyl group in the structural formula can further improve its corrosion inhibition performance, can form hydrogen bonds with the metal surface, increase the adsorption stability of the molecule on the metal surface, thereby forming a denser and more solid protective film, better preventing corrosive media from contacting the IPM metal, slowing down its corrosion rate, and extending its service life, thereby terminating the free radical thermal oxidation reaction of the IPM, and thus effectively preventing the IPM metal surface from being oxidized. On the other hand, the hydrophobic long-chain groups are oriented on the metal surface to form a dense hydrophobic layer, which can not only hinder the diffusion and migration of corrosion reactants, but also play a role in promoting the corrosion inhibition performance of the compound. Since palmitic acid can be extracted from animals and plants, it has the characteristics of wide sources, low price, environmental friendliness and thermal stability.

[0013] The beneficial effects of the present invention are as follows: the water-based flux cleaning agent obtained by the present invention has a significant cleaning effect on flux, solder paste and fine particles on semiconductor electronic devices, can maintain the brightness of solder joints, has good surface insulation performance, and can effectively prevent oxidation of the metal surface of the IPM module. DETAILED DESCRIPTION

[0014] The present invention is further described below in conjunction with the preferred technical solutions and comparative examples in the examples. These embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by technicians without creative work are within the scope of protection.

[0015] Unless otherwise specified, the materials and reagents used in the following examples can be obtained from commercial sources.

[0016] The unit of the portion may be gram, kilogram, ton, or other weight unit.

[0017] A water-based solder flux cleaning agent for integration, wherein the raw materials used are calculated by weight percentage as follows: 30-50% alcohol ether solvent, 1-5% organic amine, 3-5% gemini imidazoline corrosion inhibitor, and 40-70% deionized water, and the sum of the weight percentages is 100%.

[0018] Wherein, the alcohol ether solvent is at least one of propylene glycol methyl ether, propylene glycol butyl ether, ethylene glycol butyl ether, dipropylene glycol propyl ether, diethylene glycol methyl ether, diethylene glycol ethyl ether, ethylene glycol tert-butyl ether, triethylene glycol ethyl ether, triethylene glycol butyl ether, tripropylene glycol methyl ether, tripropylene glycol ethyl ether and dipropylene glycol dimethyl ether.

[0019] The organic amine is any one of ethylenediamine, ethanolamine, tri-n-butylamine, methyldiethanolamine, alkyl alcoholamine, triethanolamine, N,N-dimethylacetamide, N,N-dimethylethanolamine, hexadecylamine, octadecylamine and isopropylamine.

[0020] The resistivity of the deionized water at 25° C. is not less than 18 MΩ·cm.

[0021] The chemical structural formula of the gemini imidazoline corrosion inhibitor is: , The preparation method is as follows: 1) Synthesis of Compound A: Palmitic acid (25.64 g, 0.1 mol) and diethylenetriamine (12.9 g, 0.12 mol) were added into a 250 mL three-necked round-bottom flask, and 40 mL of xylene was added as a water-carrying agent; after stirring at room temperature for 0.5 h, the temperature was raised to 140 °C and heated for 2 h to amidate to obtain a primary amine; then the temperature was raised to 240 °C and the cyclization reaction was carried out for 6 h to obtain compound A.

[0022] 2) Synthesis of Gemini Imidazoline Corrosion Inhibitor: Compound A was added to the reaction vessel, and then 4 mL of epichlorohydrin was added. The temperature was programmed to 90 °C, and the reaction was continued for 5 h. The product was cooled to room temperature and filtered to obtain a crude product. The product was recrystallized 5 times with acetone / isopropanol and dried in vacuo at 50 °C for 48 h to obtain the corresponding gemini imidazoline corrosion inhibitor.

[0023] Analysis of the obtained hydrogen nuclear magnetic resonance spectrum showed that the chemical shifts were (δ): 1.26 (m, 32H, CH2); 1.29 (m, 4H, CH2); 1.30 (m, 8H, CH2); 1.33 (m, 4H, CH2); 1.40 (m, 4H, CH2); 1.54 (m, 4H, CH2); 2.26 (t, 4H, CH2); 3.4 (m, 4H, CH2); 3.40 (m, 1H, CH); 3.75 (t, 4H, CH2); 4.72 (d, 4H, CH2); 4.8 (d, 1H, OH); 8.52 (s, 4H, NH2), which proved that the gemini imidazoline corrosion inhibition surfactant was successfully synthesized.

[0024] Example: Prepare a water-based flux cleaning agent according to the formula in Table 1. The specific preparation method is to first add deionized water to a stirring kettle with a rotation speed of 500r / min at room temperature, and then add alcohol ether solvent, organic amine, and gemini imidazoline corrosion inhibitor in sequence. Each time a material is added, it is necessary to wait for it to be completely dissolved before adding the next material. After the addition is completed, continue stirring for 30 minutes, and then filter through three 1μm filter elements and two 0.5μm filter elements to obtain the target product.

[0025] Table 1 Components and dosage of water-based flux cleaning agent The cleaning effect, oxidation condition, and aluminum wire thrust of the obtained water-based flux cleaning agent were tested, and the results are shown in Table 2: 1. Cleaning effect test Test method: First, heat the cleaning agent to 55°C, then put in the DIP26 fake film for constant temperature ultrasonic cleaning for 5 minutes, then take out the fake film, spray it with pure water, and then put it into three pure water rinsing tanks, constant temperature ultrasonic cleaning for 3 minutes at 45°C, and the ultrasonic frequency is 40HZ. Finally, after two hot air cutting processes, the water stains on the surface are blown dry. Take out the cleaned fake film and use a microscope to observe the cleaning situation. The evaluation method is as follows: ◎: The surface is clean, without flux and other dirt residues.

[0026] ○: The surface is clean, with little flux or dirt residue.

[0027] ×: The surface is not very clean and there is a lot of flux or dirt residue.

[0028] 2. Oxidation test Test method: The cleaned fake film is subjected to a power-on test under the test conditions of T a (Temperature) = 85℃, RH = 85±5% (230kPa), Vce = 42V, 96Hrs, observe and record the oxidation phenomenon and time on the surface of the fake film.

[0029] 3. Aluminum wire thrust test Test method: Bond the cleaned fake piece with aluminum wire, hook the middle of the aluminum wire with a dynamometer, pull the wire off at a uniform speed, and record the instantaneous tensile force after the wire breaks.

[0030] If it is greater than 450g, the thrust can be judged as qualified.

[0031] Table 2 Performance test results of water-based flux cleaning agent From the results in Table 2, it can be seen that when Examples 1-4 are within a reasonable proportion range, the cleaning requirements for flux and other dirt can be met, and the antioxidant performance is significantly improved. The thrust of the aluminum wire is far greater than the qualified value, indicating that the use of the gemini imidazoline corrosion inhibitor can meet the cleaning requirements for flux, solder paste, and fine particles on semiconductor electronic devices, and maintain the brightness of the solder joints. It can also effectively prevent the metal surface of the IPM module from oxidation, ensuring that the aluminum wire will not have false welding.

[0032] And from the comparison with comparative examples 1-4, it can be further found that the cleaning agent prepared by compound A has local oxidation phenomenon in the fake film, indicating that the various performances of compound A are limited. Secondly, no gemini imidazoline corrosion inhibitor is added in comparative example 3, and hexadecylamine is replaced with methyldiethanolamine, and its cleaning effect is reduced, indicating that hexadecylamine has a good synergistic effect on the cleaning effect. After propylene glycol butyl ether is replaced with dipropylene glycol butyl ether in comparative example 2, there are more soldering flux and other dirty residues in the fake film after cleaning, and the oxidation problem will be further deepened at the same time, indicating that the use of dipropylene glycol butyl ether as a solvent will have a negative effect in terms of cleaning and anti-oxidation. It can be seen from comparative example 4 that after adding a small amount of gemini imidazoline corrosion inhibitor, the cleaning effect and aluminum wire thrust can meet the requirements, but the antioxidant capacity is not good, indicating that the use amount of gemini imidazoline corrosion inhibitor needs to be within a suitable ratio range.

[0033] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. A water-based flux cleaning agent for integration, characterized in that: The raw materials used include by weight percentage: Alcohol ether solvent 30-50%; Organic amine 1-5%; Gemini imidazoline corrosion inhibitor 3-5%; Deionized water 40-70%; The sum of the above weight percentages is 100%.

2. The water-based flux cleaning agent according to claim 1, characterized in that: The raw materials used include, by weight percentage: 40-45% of alcohol ether solvent, 3-5% of organic amine, 3-5% of gemini imidazoline corrosion inhibitor, and 47-50% of deionized water, and the sum of the above weight percentages is 100%.

3. The water-based flux cleaning agent according to claim 2, characterized in that: The raw materials used include, by weight percentage: 45% of alcohol ether solvent, 5% of organic amine, 3% of gemini imidazoline corrosion inhibitor, and 47% of deionized water.

4. The water-based flux cleaning agent according to claim 1, characterized in that: The alcohol ether solvent is at least one of propylene glycol methyl ether, propylene glycol butyl ether, ethylene glycol butyl ether, dipropylene glycol propyl ether, diethylene glycol methyl ether, diethylene glycol ethyl ether, ethylene glycol tert-butyl ether, triethylene glycol ethyl ether, triethylene glycol butyl ether, tripropylene glycol methyl ether, tripropylene glycol ethyl ether, and dipropylene glycol dimethyl ether.

5. The water-based flux cleaning agent according to claim 4, characterized in that: The alcohol ether solvent is propylene glycol butyl ether.

6. The water-based flux cleaning agent according to claim 1, characterized in that: The organic amine is any one of ethylenediamine, ethanolamine, tri-n-butylamine, methyldiethanolamine, alkyl alcoholamine, triethanolamine, N,N-dimethylacetamide, N,N-dimethylethanolamine, hexadecylamine, octadecylamine and isopropylamine.

7. The water-based flux cleaning agent according to claim 6, characterized in that: The organic amine is hexadecylamine.

8. The water-based flux cleaning agent according to claim 1, characterized in that: The raw materials used include, by weight percentage: 45% of propylene glycol butyl ether, 5% of hexadecylamine, 3% of gemini imidazoline corrosion inhibitor, and 47% of deionized water.

9. The water-based flux cleaning agent according to claim 1, characterized in that: The chemical structural formula of the gemini imidazoline corrosion inhibitor is: 。 10. The water-based flux cleaning agent according to claim 1, characterized in that: The resistivity of the deionized water at 25° C. is not less than 18 MΩ·cm.

Images