CN106876005B - Sn-Cu composite electron slurries and preparation method thereof - Google Patents

Abstract

The invention discloses a Sn-Cu composite electronic paste, which consists of the following components according to mass percentage: 55%-85% of pre-coated copper powder, 5%-15% of tin powder, and 10%-30% of organic carrier , which add up to 100%. The invention also discloses a preparation method of the Sn-Cu composite electronic paste and a printing method of the Sn-Cu composite electronic paste. The present invention uses chlorinated paraffin to pre-coat the surface-modified copper powder, uses tin powder as the bonding phase, and uniformly mixes the conductive phase with tin powder and an organic carrier to prepare a Sn-Cu composite electronic paste, which can Reduce the sintering temperature of the electronic paste, effectively control the oxidation rate of the copper powder during the sintering process, thereby improving the electrical conductivity and adhesion of the electronic paste; the process route is simple, the raw materials are easy to obtain, the production cost is low, and it does not contain lead and cadmium ingredients, no pollution.

Description

Sn-Cu composite electronic paste and preparation method thereof

technical field

The invention belongs to the technical field of electronic paste, and relates to a Sn-Cu composite electronic paste, and also relates to a preparation method of the Sn-Cu composite electronic paste, and a printing method of the Sn-Cu composite electronic paste .

Background technique

Electronic paste has been widely used in electronic industries such as integrated circuits, surface packaging, and microelectronics technology. With the continuous development of modern technology, the electronics industry has higher and higher requirements for the performance of electronic pastes, and the high-performance electronic pastes are relatively expensive, which inhibits the development of the field of electronic pastes.

Electronic paste is generally composed of three parts: conductive phase, binder phase and organic carrier. Improving the performance of electronic paste generally starts with the conductive phase and binder phase. To solve the problem of the adhesiveness of electronic paste, it is necessary to change the adhesion. phase composition. During the sintering process of the electronic paste, the sintered conductive phase is bonded to the ceramic substrate due to the binding effect of the adhesive phase, so the selection of the adhesive phase directly affects the quality of the electronic paste.

Existing electronic pastes basically use glass frit as a binder phase, but glass frit has poor electrical conductivity, which affects the electrical conductivity of the electronic paste. Therefore, the development of high-performance, low-cost electronic paste is also one of the research hotspots in the field of electronic paste today.

Contents of the invention

The purpose of the present invention is to provide a Sn-Cu composite electronic paste, which solves the problems of poor electrical conductivity, poor sintering adhesion, high sintering temperature and easy oxidation of copper powder in the prior art.

The second object of the present invention is to provide a method for preparing the Sn-Cu composite electronic paste.

The third object of the present invention is to provide a printing method of this kind of Sn-Cu composite electronic paste.

The technical solution adopted in the present invention is that a Sn-Cu composite electronic paste is composed of the following components according to the mass percentage: 55%-85% of pre-coated copper powder, 5%-15% of tin powder, organic carrier 10% to 30%, the total is 100%.

The second technical scheme adopted in the present invention is a preparation method of Sn-Cu composite electronic paste, which is implemented according to the following steps:

Step 1, prepare pre-coated copper powder

Weigh the copper powder, and pickle the copper powder with dilute sulfuric acid with a mass fraction of 5% to 10%; use formaldehyde solution to clean the pickled copper powder for 3-5 times, and mix the cleaned copper powder into Stir evenly in the melted chlorinated paraffin, then place it in an ammonia or nitrogen atmosphere, and dry it at a temperature of 80°C to 90°C to obtain pre-coated copper powder;

Step 2, prepare the organic vehicle

The components of the organic carrier are composed of organic solvents, thickeners, surfactants, coupling agents, and defoamers; according to mass percentages, 75% to 85% of organic solvents, 10% to 15% of thickeners, 1% to 3% surfactant, 2% to 4% coupling agent, 1% to 3% defoamer; stirring and mixing the five components evenly to obtain an organic carrier;

Step 3, preparing Sn-Cu composite electronic paste

According to the mass percentage, weigh 55% to 85% pre-coated copper powder, 5% to 15% tin powder, and 10% to 30% organic carrier respectively, and the sum of the mass percentages of each component is 100%; the prepared Pre-coated copper powder and tin powder are mixed, ground and stirred, then added to the organic carrier prepared in step 2, and stirred evenly; then ultrasonic dispersion is carried out to make the pre-coated copper powder and tin powder dispersed evenly, and the Sn-Cu composite Electronic paste.

The third technical solution adopted in the present invention is a printing method of Sn-Cu composite electronic paste, which adopts the above-mentioned Sn-Cu composite electronic paste and implements according to the following steps:

Step 1. Carry out circuit printing of Sn-Cu composite electronic paste

Clean the alumina ceramic substrate with ethanol, and then print the Sn-Cu composite electronic paste on the alumina ceramic substrate by screen printing; repeatedly print the Sn-Cu composite electronic paste on each alumina ceramic substrate 3 -7 times, the total thickness of the printing film is 0.04-0.2 mm; after the printing is completed, put the alumina ceramic substrate in a horizontal state, and let it stand for 5-20 minutes until the screen texture disappears;

Step 2. Burn the sample

Put the alumina ceramic substrate prepared in the previous step into the reaction kettle, and heat it to the sintering temperature at an increasing rate of 5-15°C/min under the protection of a nitrogen atmosphere. After ~15 minutes, cool down with the furnace to prepare an alumina ceramic substrate sample.

The beneficial effect of the present invention is,

1) For the Sn-Cu composite electronic paste, the surface-modified spherical copper powder with a particle size of 1 to 15 μm is pre-coated with molten chlorinated paraffin to obtain a pre-coated copper powder, and then dried Obtain coated powder. The Sn-Cu composite electronic paste is obtained by uniformly mixing the conductive phase with the tin powder and the organic carrier by using tin powder as the bonding phase.

2) In the Sn-Cu composite electronic paste, copper powder is pre-coated with chlorinated paraffin, and the better stability of chlorinated paraffin enables the copper powder after pickling to be preserved for a long time without being oxidized. Utilizing the property that chlorinated paraffin can decompose by itself at 120°C and can promote the oxidative decomposition of metals, it can promote the decomposition of a very small amount of residual copper oxide in copper powder during sintering, and further improve the conductivity of electronic paste.

3) The Sn-Cu composite electronic paste uses tin powder to replace the glass powder used in the bonding phase of the general electronic paste, which can reduce the sintering temperature of the electronic paste and effectively control the oxidation rate of the copper powder during the sintering process, thereby improving Conductivity and adhesion of electronic paste;

4) The Sn-Cu composite electronic paste and its preparation and printing applications have a simple process route, readily available raw materials, low production cost, no lead and cadmium components, and no pollution.

Detailed ways

The present invention will be described in detail below in combination with specific embodiments.

The Sn-Cu composite electronic paste of the present invention is composed of the following components according to mass percentage: 55% to 85% of pre-coated copper powder, 5% to 15% of tin powder, and 10% to 30% of organic carrier, the total is 100%.

The preparation method of the Sn-Cu composite electronic paste of the present invention is implemented according to the following steps:

Step 1, prepare pre-coated copper powder

Weigh copper powder with a particle size of 1 to 15 μm, and pickle the copper powder with dilute sulfuric acid with a mass fraction of 5% to 10% (deoxidation treatment); use formaldehyde solution to clean the copper powder after pickling for 3 -5 times, mix the cleaned copper powder into the melted chlorinated paraffin, stir evenly, then place it in an ammonia or nitrogen atmosphere, and dry it at a temperature of 80°C to 90°C to obtain pre-coated copper powder , as a spare conductive phase.

Step 2, prepare the organic vehicle

The components of the organic carrier are composed of organic solvents, thickeners, surfactants, coupling agents, and defoamers; according to mass percentages, 75% to 85% of organic solvents, 10% to 15% of thickeners, 1% to 3% surfactant, 2% to 4% coupling agent, 1% to 3% defoamer; stirring and mixing the five components evenly to obtain an organic carrier;

Among them, the organic solvent is a mixture of one or more of terpineol, ethyl benzoate, and turpentine; the thickener is a mixture of one or more of ethyl cellulose, acrylic resin, and silicone gel; The surfactant is one or more mixtures of egg curd and glyceryl monostearate.

Step 3, preparing Sn-Cu composite electronic paste

According to the mass percentage, weigh 55% to 85% of the pre-coated copper powder, 5% to 15% of the tin powder, and 10% to 30% of the organic carrier, and the sum of the mass percentages of each component is 100%;

Using tin powder as the binder phase, the particle size of the tin powder is 1-15 μm; mixing the prepared pre-coated copper powder and tin powder, grinding and stirring, then adding to the organic carrier prepared in step 2, and stirring evenly;

Ultrasonic dispersion is then carried out, so that the pre-coated copper powder and tin powder are uniformly dispersed, and the Sn-Cu composite electronic paste is prepared.

The printing method of Sn-Cu composite electronic paste of the present invention is implemented according to the following steps:

Step 1. Carry out circuit printing of Sn-Cu composite electronic paste

Clean the alumina ceramic substrate with ethanol (through comparative tests, the printing effect of the alumina ceramic substrate is better), then adopt the mode of screen printing to print the above-mentioned Sn-Cu composite electronic paste on the alumina ceramic substrate, The squeegee pressure applied when preparing each sample is controlled consistently; repeat printing Sn-Cu composite electronic paste 3-7 times on each alumina ceramic substrate, and the total thickness of the printing film is 0.04-0.2 mm; after printing is completed Place the alumina ceramic substrate in a horizontal state and let it stand for 5-20 minutes until the screen pattern disappears.

Step 2. Burn the sample

Put the alumina ceramic substrate prepared in the previous step into the reaction kettle, and heat it to the sintering temperature at an increasing rate of 5-15°C/min under the protection of a nitrogen atmosphere. After ~15 minutes, cool down with the furnace to prepare an alumina ceramic substrate sample.

Example 1

Step 1, take the (spherical) copper powder with a particle size of 1 μm, and use dilute sulfuric acid with a mass fraction of 5% to pickle the copper powder; Mix the copper powder into the melted chlorinated paraffin, and dry it at a temperature of 80°C in an ammonia or nitrogen atmosphere until it is dried to obtain a pre-coated copper powder, which is used as a conductive phase for later use;

Step 2, according to mass percentage 75%: 15%: 3%: 4%: 3%, weigh each component of organic carrier terpineol, ethyl cellulose, egg curd, coupling agent, defoamer, and mix them in a beaker , stir evenly to obtain an organic carrier;

Step 3, mix the prepared pre-coated copper powder with tin powder with a particle size of 1 μm, grind and stir, and then add it to the organic vehicle prepared in step 2. The mass percentages of the three components are: pre-coated copper powder 55 %, tin powder 15%, organic carrier 30%; ultrasonic dispersion is carried out to make the dispersion of copper powder and tin powder more uniform, and to prepare Sn-Cu composite electronic paste;

Step 4, clean the alumina ceramic substrate with ethanol, and then print the Sn-Cu composite electronic paste on the alumina ceramic substrate by screen printing, and the pressure of the squeegee applied when preparing each sample should be controlled consistently , and repeated printing 3 times; the total thickness of the printing film is 0.04 mm; after the printing is completed, the alumina ceramic substrate is placed horizontally and left to stand for 5 minutes;

Step 5, put the alumina ceramic substrate prepared in the previous step into the reaction kettle, and under the protection of nitrogen atmosphere, heat it to the sintering temperature at a rate of 5°C/min. The sintering temperature is 250°C, keep it for 5 minutes, and The furnace was cooled and samples were prepared.

Example 2

Step 1, take the (spherical) copper powder with a particle size of 10 μm, and pickle the copper powder with dilute sulfuric acid with a mass fraction of 8%; use formaldehyde solution to clean the copper powder after pickling 4 times, and wash the copper powder Mix the copper powder into the melted chlorinated paraffin, and dry it at a temperature of 85°C in an ammonia or nitrogen atmosphere until it is dried to obtain a pre-coated copper powder, which is used as a conductive phase for later use;

Step 2, according to the mass ratio of 80%: 12%: 2%: 4%: 2%, weigh the components of organic carrier ethyl benzoate, acrylic resin, egg curd, coupling agent, defoamer, and mix them in a beaker , and stir evenly to obtain an organic carrier;

Step 3, mix the prepared pre-coated copper powder with tin powder with a particle size of 5 μm, grind and stir, and then add it to the organic vehicle prepared in step 2. The mass percentages of the three components are: pre-coated copper powder 70%, tin powder 10%, organic carrier 20%; ultrasonic dispersion is carried out to make the dispersion of copper powder and tin powder more uniform, and to prepare Sn-Cu composite electronic paste;

Step 4, clean the alumina ceramic substrate with ethanol, and then print the Sn-Cu composite electronic paste on the alumina ceramic substrate by screen printing, and the pressure of the squeegee applied when preparing each sample should be controlled consistently , and repeated printing 5 times; the total thickness of the printing film is about 0.1 mm; after the printing is completed, place the alumina ceramic substrate horizontally and let it stand for about 15 minutes;

Step 5, put the alumina ceramic substrate prepared in the previous step into the reaction kettle, and under the protection of nitrogen atmosphere, heat it to the sintering temperature at a rate of 10°C/min. The sintering temperature is 350°C, keep it for 10 minutes, then The furnace was cooled and samples were prepared.

Example 3

Step 1, take the (spherical) copper powder with a particle size of 15 μm, and pickle the copper powder with dilute sulfuric acid with a mass fraction of 10%; Mix the copper powder into the melted chlorinated paraffin, and dry it at a temperature of 90°C in an ammonia or nitrogen atmosphere until it is dried to obtain a paraffin-coated copper powder, which is used as a conductive phase for standby;

Step 2, according to the mass ratio of 85%: 10%: 1%: 3%: 1%, weigh the components of the organic carrier, turpentine, silicone gel, glyceryl monostearate, coupling agent, and defoamer, and mix them in In a beaker, stir evenly to obtain an organic carrier;

Step 3, mix the prepared pre-coated copper powder with tin powder with a particle size of 15 μm, grind and stir, and then add it to the organic vehicle prepared in step 2. The mass percentages of the three components are: pre-coated copper powder 85%, tin powder 5%, organic carrier 10%; ultrasonic dispersion is carried out to make the dispersion of copper powder and tin powder more uniform, and to prepare Sn-Cu composite electronic paste;

Step 4, clean the alumina ceramic substrate with ethanol, and then print the Sn-Cu composite electronic paste on the alumina ceramic substrate by screen printing, and the pressure of the squeegee applied when preparing each sample should be controlled consistently , and repeated printing 7 times; the total thickness of the printing film is 0.2 mm; after the printing is completed, the alumina ceramic substrate is placed horizontally and left to stand for 20 minutes;

Step 5, put the alumina ceramic substrate prepared in the previous step into the reaction kettle, and under the protection of nitrogen atmosphere, heat it to the sintering temperature at a rate of 15°C/min. The sintering temperature is 450°C, keep it warm for 15 minutes, The furnace was cooled and samples were prepared.

Claims (3)

1. a preparation method of Sn-Cu composite electronic paste, is characterized in that, implements according to the following steps: Step 1, prepare pre-coated copper powder Weigh the copper powder, and pickle the copper powder with dilute sulfuric acid with a mass fraction of 5% to 10%; use formaldehyde solution to clean the pickled copper powder for 3-5 times, and mix the cleaned copper powder into Stir evenly in the melted chlorinated paraffin, then place it in an ammonia or nitrogen atmosphere, and dry it at a temperature of 80°C to 90°C to obtain pre-coated copper powder; Step 2, prepare the organic vehicle The components of the organic carrier are composed of organic solvents, thickeners, surfactants, coupling agents, and defoamers; according to mass percentages, 75% to 85% of organic solvents, 10% to 15% of thickeners, 1% to 3% surfactant, 2% to 4% coupling agent, 1% to 3% defoamer; stirring and mixing the five components evenly to obtain an organic carrier; Step 3, preparing Sn-Cu composite electronic paste According to the mass percentage, weigh 55% to 85% pre-coated copper powder, 5% to 15% tin powder, and 10% to 30% organic carrier respectively, and the sum of the mass percentages of each component is 100%; the prepared Pre-coated copper powder and tin powder are mixed, ground and stirred, then added to the organic carrier prepared in step 2, and stirred evenly; then ultrasonic dispersion is carried out to make the pre-coated copper powder and tin powder dispersed evenly, and the Sn-Cu composite Electronic paste. 2. The method for preparing Sn-Cu composite electronic paste according to claim 1, characterized in that: the particle diameters of the copper powder and the tin powder are both 1-15 μm. 3. A printing method of Sn-Cu composite electronic paste, characterized in that: adopt the Sn-Cu composite electronic paste prepared by claim 1 or 2, implement according to the following steps: Step 1. Carry out circuit printing of Sn-Cu composite electronic paste Clean the alumina ceramic substrate with ethanol, and then print the Sn-Cu composite electronic paste on the alumina ceramic substrate by screen printing; repeatedly print the Sn-Cu composite electronic paste on each alumina ceramic substrate 3 -7 times, the total thickness of the printing film is 0.04-0.2 mm; after the printing is completed, put the alumina ceramic substrate in a horizontal state, and let it stand for 5-20 minutes until the screen texture disappears; Step 2. Burn the sample Put the alumina ceramic substrate prepared in the previous step into the reaction kettle, and heat it to the sintering temperature at an increasing rate of 5-15°C/min under the protection of a nitrogen atmosphere. After ~15 minutes, cool down with the furnace to prepare an alumina ceramic substrate sample.