CN101719395B - Macromolecular solution dispersing medium with complete combustion and volatilization for dispensing organic powder - Google Patents

Abstract

A fully combustible and volatile polymer solution dispersion medium for dispersing inorganic powders. Its composition features are: dissolving nitrocellulose or ethyl cellulose in ethyl acetate, terpineol, butyl carbitol, butyl carbitol acetate and other single or mixed solvents, adding silicone block copolymerization The polymer solution formed by additives such as hyperdispersant and defoamer is used as the dispersion medium of inorganic powder to make electronic paste. Its performance characteristics are that the electronic paste has good uniform dispersion stability and easy-to-form rheology. During the process of making electronic components through high-temperature sintering, the dispersion medium can be burned after being kept in the air for 10 minutes at a temperature as low as 290 ° C. Volatile more than 99.99% of its original mass.

Description

A fully combustible and volatile polymer solution dispersion medium for dispersing inorganic powders

technical field

The invention relates to a completely combustible and volatile organic viscous polymer solution dispersion medium for dispersing inorganic powder. It is used to make paste-like electronic paste. During the process of making electronic components through high-temperature sintering, the electronic paste can be kept at a temperature as low as 290°C and kept in the air for 10 minutes. The organic polymer solution dispersion medium can burn and volatilize its original The quality score is above 99.99%. Eliminate the influence of residual carbon on the performance of electronic components after sintering of electronic paste. The invention belongs to the field of electronic materials for electronic components.

Background technique

In the production process of various electronic components, sensitive functional components (photosensitive, moisture sensitive, gas sensitive) and various photoelectric display devices, it is often necessary to make inorganic powders with functions of light, heat, electricity, and magnetism into slurry, which is easy to use The screen printing or coating method is used to form the shape required by the device, and then it is solidified through a high-temperature sintering process to prepare functional electronic components. In the process of making the slurry, it is necessary to uniformly disperse various inorganic functional powders in the organic viscous polymer solution. Organic viscous polymer solutions usually consist of thickened polymers and solvents. Depending on the type and molecular weight of the polymer used, usually after high-temperature sintering and cooling, the polymer cannot be completely burned and volatilized, and there is residual carbon with a mass fraction of 1% to 10%, which will degrade the performance of electronic components. The dispersion medium of the polymer solution disclosed by the invention can burn and volatilize more than 99.99% of its original mass after the dispersion medium of the organic polymer solution is kept at a temperature as low as 290° C. for 10 minutes in the air. The problem of the influence of residual carbon on the performance of components after sintering of the paste is basically solved.

The patent of Tianjin University with publication number CN1870310 discloses a nano-silver solder prepared by uniformly mixing nano-silver particles with a particle size of less than 100nm, fish oil as a dispersant, α-terpineol as a binder, and acetone as a solvent with the assistance of an ultrasonic water bath. paste. There is no polymer or polymer in the dispersion medium used, which will make the silver paste made difficult to stabilize for a long time, and its printability has not been evaluated.

The advantages of the present invention are: the use of nitrocellulose and ethyl cellulose as thickeners not only ensures that the slurry has good dispersion stability and screen printing suitability, but also eliminates the carbon residue after the slurry is sintered, ensuring Properties of the prepared electronic components.

Contents of the invention

Dissolve nitrocellulose with a mass percentage of 1% to 15% in ethyl acetate alone or ethyl acetate with terpineol, butyl carbitol, turpentine, butyl carbitol acetate, diphthalate In the mixed solvent of methyl ester, dibutyl phthalate, etc., add silicone block copolymer hyperdispersant and defoamer and other additives, that is, in the present invention, it can be used to disperse inorganic powder the dispersion medium.

Dissolve ethyl cellulose with a mass percentage of 1% to 15% in terpineol alone or terpineol with ethyl acetate, butyl carbitol, turpentine, butyl carbitol acetate, phthalic acid In mixed solvents such as dimethyl ester and dibutyl phthalate, add silicone block copolymer hyperdispersants and defoamers and other additives, which is what is referred to in the present invention and can be used to disperse inorganic powders. the dispersion medium.

The beneficial effect of the present invention is: (1) the thickening agent that uses macromolecule nitrocellulose or ethyl cellulose as the solution is compared with the dispersion medium that does not use macromolecule as the thickening agent. When used to disperse nano or micro inorganic powder, it has better uniform dispersion stability and rheology for easy molding. (2) Compared with the dispersion medium using other polymers as the thickener of the solution, it has the characteristics of almost zero residual carbon after high-temperature sintering, which eliminates the influence of residual carbon on the performance of electronic components.

Detailed ways

The present invention will be further illustrated by the following specific examples.

Example 1

A transparent dielectric paste for making a front substrate of a plasma display. The front substrate of the plasma display needs to make a layer of visible light transparent glass layer with a thickness of 10-20 microns.

Grind the dielectric glass powder that meets the requirements to an average particle size of 3 microns and a maximum particle size of less than 10 microns.

The nitrocellulose with a mass percentage of 5% was dissolved in ethyl acetate or a mixed solvent of ethyl acetate, butyl carbitol, and dibutyl phthalate (mass ratio: 50:25:25). Add 2% organic silicon block copolymer hyperdispersant and 2% defoamer to prepare a uniform solution, which is the dispersion medium referred to in the present invention. The medium glass powder with a mass fraction of 75% is uniformly dispersed in the dispersion medium with a mass fraction of 25%, and is uniformly dispersed with a three-roll mill to prepare a medium slurry. The rheology of the slurry is a typical shear thinning body, and it has good screen printing suitability. Screen-print the paste onto a glass substrate, and then heat it in air for 15 minutes at a peak temperature of 580°C for sintering. After cooling, the average visible light transmittance of the glass is measured to be greater than 87%, and the flatness of the printed dielectric layer after sintering fulfil requirements. The residual carbon content in the glass medium layer is analyzed by ICP-AES (inductively coupled plasma-atomic emission spectrometry) and the mass percentage is less than 0.001%.

Another example is that 4% ethyl cellulose is dissolved in terpineol or a mixed solvent of terpineol, butyl carbitol acetate and dimethyl phthalate (mass ratio is 50: 25:25). Adding 4% of the organic silicon block copolymer hyperdispersant and 2% of the defoamer to prepare a uniform solution is also the dispersion medium referred to in the present invention. The medium glass powder with a mass fraction of 78% is uniformly dispersed in the dispersion medium with a mass fraction of 22%, and is uniformly dispersed with a three-roll mill to prepare a medium slurry. The rheology of the slurry is a typical shear thinning body, and it has good screen printing suitability. Screen-print the paste onto the glass substrate, then keep it warm in the air for 10 minutes at the peak temperature of 585°C for sintering, after cooling, measure the visible light average transmittance of broken glass greater than 87%, and the printed dielectric layer is smooth after sintering meet the requirements. The residual carbon content in the glass medium layer is analyzed by ICP-AES (inductively coupled plasma-atomic emission spectrometry) and the mass percentage is less than 0.001%.

The advantages of the present invention in this embodiment are: (1) The slurry has very good rheology to ensure the flatness of the transparent medium layer produced. (2) After sintering, the residual carbon is almost zero to ensure a high visible light transmittance.

Example 2

Making nano-silver conductive paste.

Inorganic powder is silver powder with a maximum particle size of less than 100 nanometers and an average particle size of 60 nanometers.

The nitrocellulose with a mass percentage of 5% was dissolved in ethyl acetate or a mixed solvent of ethyl acetate, butyl carbitol acetate, and dimethyl phthalate (mass ratio: 50:25:25). Add 6% of organic silicon block copolymer hyperdispersant and 2% of defoamer to prepare a uniform solution, which is the dispersion medium referred to in the present invention. Nano-silver powder with a mass fraction of 75% is uniformly dispersed in a dispersion medium with a mass fraction of 25%, and is uniformly dispersed with a three-roll mill to prepare a nano-silver conductive paste. The rheology of the slurry is a typical shear thinning body, and it has good screen printing suitability. Screen-print the slurry onto a single crystal silicon substrate with a gold-plated layer on the surface, and then sinter at a peak temperature of 290°C and keep it in the air for 10 minutes. The dispersion medium of the organic polymer solution is basically completely volatilized. After cooling, the silver sintered film White and dense, it adheres well to the gold-plated layer. ICP-AES (Inductively Coupled Plasma-Atomic Emission Spectroscopy) is used to analyze the mass percentage of residual carbon in the silver layer to be less than 0.01%.

Another example is to dissolve ethyl cellulose with a mass percentage of 6% in terpineol or a mixed solvent of terpineol and butyl carbitol (mass ratio is 75:25). Adding 5% organic silicon block copolymer hyperdispersant and 2% defoamer to prepare a uniform solution is also the dispersion medium referred to in the present invention. The nano-silver powder with a mass fraction of 76% is uniformly dispersed in a dispersion medium with a mass fraction of 24%, and is uniformly dispersed with a three-roll mill to prepare a medium slurry. The rheology of the slurry is a typical shear thinning body, and it has good screen printing suitability. Screen-print the slurry onto a single crystal silicon substrate with a gold-plated layer on the surface, and then sinter at a peak temperature of 300°C in air for 10 minutes. The dispersion medium of the organic polymer solution is basically completely volatilized. After cooling, the silver sintered film White and dense, it adheres well to the gold-plated layer. ICP-AES (Inductively Coupled Plasma-Atomic Emission Spectroscopy) is used to analyze the mass percentage of residual carbon in the silver layer to be less than 0.01%.

In this embodiment, the advantages of the present invention are:

According to the different binders for adhering silver powder, silver paste can be divided into two categories: one is to adhere silver powder to the substrate by melting low-melting glass powder at high temperature; the other is to use epoxy or polyester The thermal curing cross-linking reaction of polymers will adhere the silver powder to the substrate at a lower temperature.

In this embodiment, due to the requirements of the device, no non-silver components can remain in the silver layer made, and it is not suitable to use evaporation or various vapor deposition processes to make the silver film layer for device production, and can only be made by thick film technology. The sintering temperature should not be higher than 300°C, in order to prevent high temperature damage to other components that are manufactured earlier in the device process. Although the melting point of silver is about 960°C, according to literature reports, the melting point of silver nanoparticles can be as low as about 100°C. In this embodiment, the nano-silver powder is dispersed in the dispersion medium referred to in the present invention to prepare a slurry. By screen printing, after sintering at a temperature lower than 290 ° C and kept in the air for 10 minutes, the organic dispersion medium is basically completely volatilized, and the silver is sintered. The residual carbon in the body is almost zero, which ensures the performance of the device. If other polymers are used as the thickener dispersion medium, after sintering at 300°C for 10 minutes in air, there will be relatively high carbon residues, which will affect the compactness of the silver sintered layer and the adhesion strength with the gold-plated layer. affect device performance.

The above embodiments are only used to illustrate and not limit the technical solution of the present invention. Those skilled in the art can understand that various changes and equivalent replacements are made to the technical solution of the present invention without departing from the principle and scope of the technical solution of the present invention. should be included in the scope of the claims of the present invention.

Claims (3)

1. A polymer solution dispersing medium that can completely combust and volatilize is used to disperse inorganic powders to make pasty electronic pastes. Its composition is (mass percentage): nitrocellulose, 1-15, and the rest are organic silicon blocks Copolymer hyperdispersant, defoamer and ethyl acetate alone or ethyl acetate with terpineol, butyl carbitol, turpentine, butyl carbitol acetate, dimethyl phthalate, ortho Mixed solvent of dibutyl phthalate. 2. the described polymer solution dispersion medium according to claim 1, is characterized in that: the viscous solution that nitrocellulose is dissolved in organic solvent formation, and organic solvent is independent ethyl acetate or ethyl acetate and pine A mixed solvent of oleyl alcohol, butyl carbitol, turpentine, butyl carbitol acetate, dimethyl phthalate, and dibutyl phthalate. 3. The polymer solution dispersion medium according to claim 1, characterized in that: more than 99.99% of its original mass fraction is volatilized when it is kept in the air for 10 minutes at a temperature as low as 290°C.