A crystalline glass powder for plating-resistant silver paste and a method for preparing the same

Abstract

The application discloses a kind of glass powder for electroplated silver paste, and chemical composition includes: SiO2 30~40%, TiO2 10~20%, B2O3 10~20%, SrO 5~10%, MgO 5~10%, ZnO 5~10%, BaO 1~10%, Na2O2~8%, Al2O3 1~5% by mass percentage.The silver paste glass powder has a suitable softening temperature, strong crystallization ability, excellent acid resistance, and has a matching thermal expansion coefficient and chemical compatibility with the ceramic substrate;The silver electrode made of the glass powder can complete the electroplating process well, and can achieve excellent adhesion strength between the silver electrode and the ceramic substrate, and is suitable for popularization and application.

Description

Technical Field

[0001] This invention belongs to the field of microelectronic packaging materials technology, specifically relating to a crystalline glass powder for electroplating silver paste and its preparation method. Background Technology

[0002] Silver electronic paste (silver paste) has become the most in-demand and widely used electronic paste due to its excellent conductivity. Silver paste is mainly composed of silver powder, an organic carrier, and glass powder mixed in a uniform ratio. It is then formed onto a substrate material through processes such as screen printing, impregnation, and casting. Drying and sintering processes are then performed to bond the silver paste to the substrate material, ultimately forming a film-like silver electrode with excellent conductivity on the substrate. During the sintering process of the silver paste, the glass powder promotes the densification of the silver electrode and improves the adhesion strength between the silver electrode and the substrate material. Although the proportion of glass powder in the silver paste is not high, typically 2.00–10.00 wt.%, it plays a decisive role in the quality of the silver electrode and subsequent components.

[0003] With the rapid development of microelectronics and integrated circuits, the Ag-Ni-Sn three-layer electrode structure is considered the most reliable electrode structure for chip components, such as the terminal electrodes of multilayer chip inductors, the terminal electrodes of multilayer ceramic capacitors, and the surface electrodes of chip resistors. Electroplating Ni and Sn layers on the electrode surface can significantly increase the conductivity, oxidation resistance, solderability, solderability, and decorative properties of silver electrodes, which is of great significance for improving the performance and lifespan of chip electronic components. Electroplating is usually carried out in acidic solutions, such as methanesulfonic acid-based electrolyte plating solutions and nickel sulfamate plating solutions, with a pH range of 4.5–5.5. This requires the glass powder used as the binder phase to have excellent acid corrosion resistance to prevent the acidic plating solution from corroding the glass phase in the silver electrode, which would weaken the bond between the silver electrode and the substrate material and affect the stability of the silver electrode.

[0004] As mentioned above, crystalline glass powder for electroplating silver paste should possess the following properties: (1) suitable softening temperature and excellent sintering density; (2) a coefficient of thermal expansion matching the ceramic substrate and good chemical compatibility; and (3) excellent acid corrosion resistance. Traditional glass powder for silver paste is mainly composed of high Pb content glass powder, such as PbO-B2O3-ZnO glass. Under the global trend of lead reduction, ZnO-V2O5-P2O5, V2O5-B2O3-TeO2, and Bi2O3-B2O3-ZnO glasses are considered the most promising candidates to replace lead-containing glass powder. However, these glasses have poor acid corrosion resistance and cannot meet the requirements of the electroplating process of silver electrodes. Therefore, further development of new glass powders for electroplating silver paste has important practical application value. Summary of the Invention

[0005] The main objective of this invention is to provide a crystalline glass powder for electroplating silver paste. This glass powder has a suitable softening temperature, strong crystallization ability, excellent acid corrosion resistance, and a matching coefficient of thermal expansion and chemical compatibility with the ceramic substrate. Silver electrodes made using this glass powder can complete the electroplating process well and achieve excellent adhesion strength between the silver electrode and the ceramic substrate, making it suitable for widespread application.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A glass powder for electroplating silver paste, the chemical composition of which by mass percentage includes: SiO2 30-40%, TiO2 10-20%, B2O3 10-20%, SrO 5-10%, MgO 5-10%, ZnO 5-10%, BaO 1-10%, Na2O 2-8%, and Al2O3 1-5%.

[0008] Preferably, the chemical composition of the glass powder for electroplating silver paste comprises, by mass percentage: SiO2 35-38%, TiO2 12-18%, B2O3 12-18%, SrO 6-10%, MgO 6-10%, ZnO 7-10%, BaO 1-5%, Na2O 2-6%, and Al2O3 2-4%.

[0009] According to the above scheme, the glass powder used for electroplating silver paste has a glass transition temperature of 580–620℃ and a coefficient of thermal expansion of 7.40–8.50℃. -1 The mass loss due to acid erosion is <0.50 wt.% (10 wt.% hydrochloric acid, 60℃, 30 min).

[0010] The above-mentioned method for preparing glass powder for electroplating silver paste includes the following steps:

[0011] 1) Weigh each raw material according to the ratio, mix the raw materials evenly, melt at high temperature, quench in water, and dry to obtain a pre-melted glass sample;

[0012] 2) The obtained pre-melted glass sample was crushed, ball-milled, dried, and sieved to obtain a D50 < 5 μm and a specific surface area of ​​20–26 m². 2 / g of glass powder for electroplating silver paste.

[0013] According to the above scheme, quartz sand, boric acid, titanium dioxide, strontium carbonate, magnesium oxide, zinc oxide, barium carbonate, sodium carbonate, and aluminum oxide can be selected as raw materials.

[0014] According to the above scheme, the temperature used in the high-temperature melting step is 1350-1450℃; the holding time is 30-80min.

[0015] According to the above scheme, the ball milling step in step 2) adopts a wet milling process, and Pingpingjia O is introduced as an additive, the amount of which is 0.05 to 0.1% of the mass of the pre-melted glass sample.

[0016] Furthermore, in the wet grinding process, the grinding agate beads account for 50-60% of the mass of the grinding slurry, the ball milling parameters are 180-360 r / min, and the grinding time is 8-10 h.

[0017] In the above scheme, the solvent used in the wet milling process is anhydrous ethanol or the like.

[0018] In the above scheme, the drying temperature is 60-80℃ and the time is 4-8h.

[0019] The present invention also discloses an electroplating silver paste based on the above-mentioned glass powder for electroplating silver paste, which includes glass powder, silver powder and organic carrier. The raw materials and their mass percentages include: 2-5% glass powder for electroplating silver paste, 70-80% silver powder and 15-25% organic carrier.

[0020] Furthermore, the silver powder is a mixture of silver powders with different particle sizes, which can effectively increase the bulk density of the silver powder and improve the wetting effect between the glass liquid phase and the silver powder during sintering, thereby improving the sintering density of the silver electrode after sintering. The silver powder includes at least two of the following spherical silver powders: spherical silver powder 1, with a median particle size of 2–3 μm and a bulk density of 3.8–4.5 kg / m³. 3 Specific surface area: 0.3–0.6 m² 2 / g; spherical silver powder 2, median particle size 0.8~1.2μm, bulk density 3.2~3.8kg / m³ 3 Specific surface area: 0.8–1.5 m² 2 / g; spherical silver powder 3, median particle size 0.5~0.8μm, bulk density 2.8~3.0kg / m³ 3 Specific surface area: 1.6–2.0 m² 2 / g.

[0021] Preferably, the mixed silver powder includes spherical silver powder 1 and spherical silver powder 2; the content of spherical silver powder 2 in the mixed silver powder is 60-85 wt.%.

[0022] According to the above scheme, the organic carrier is a mixture of different organic substances, including at least one of terpineol, ethyl cellulose, diethylene glycol butyl ether, etc.

[0023] Preferably, the organic carrier comprises terpineol, ethyl cellulose and diethylene glycol butyl ether, and the components and their mass percentages are: terpineol 75-85 wt%, ethyl cellulose 5-15 wt%, and diethylene glycol butyl ether 5-10 wt%.

[0024] The above-mentioned electroplating resistant silver paste is used to prepare silver electrodes. The specific steps include: screen printing the obtained silver paste onto the surface of the substrate, and then sintering it at a temperature of 800-850°C for 5-10 minutes under a protective atmosphere.

[0025] In the above scheme, the coefficient of thermal expansion of the substrate is 7×10⁻⁶. -6 ~9×10 -6 Specifically, widely used substrates such as 96Al2O3 ceramics can be selected.

[0026] The silver electrode prepared according to the above scheme has an adhesion force >12 kgf and an adhesion strength >300 kgf / cm². 2 .

[0027] The principle of this invention is as follows:

[0028] The crystalline glass powder for electroplating silver paste obtained by this invention has a high content of SiO2 and B2O3, with mass fractions of 30-40% and 10-20%, respectively, which helps to form a glass network structure with low glass transition temperature and high acid erosion resistance.

[0029] The crystalline glass powder for electroplating silver paste obtained in this invention has a high TiO2 content, which is beneficial for enhancing the crystallization ability of the glass powder, enabling the rapid precipitation of a large number of nano-sized crystals, and also helps to improve the acid resistance and electroplating resistance of the sealing glass. Simultaneously, by controlling the amount of B2O3, the content of [BO3]trigonal and [BO4] tetrahedrons in the glass is adjusted to ensure acid corrosion resistance. The TiO2 content in the electroplating silver paste glass of this invention needs to be adjusted in conjunction with the B2O3 content in the composition; the TiO2 / B2O3 ratio is preferably in the range of 0.66 to 1.50; and the preferred mass fraction of TiO2 is 14% to 18%.

[0030] The crystalline glass powder for electroplating silver paste obtained in this invention incorporates various alkali metal / alkaline earth metal oxides, including SrO, MgO, ZnO, BaO, and Na2O. In the glass, the different types of alkali metal / alkaline earth metal ions, due to their different ionic radii, form a more compact packing, which helps to precipitate uniformly dispersed crystals.

[0031] The Al2O3 content in the crystalline glass powder for electroplating silver paste obtained by this invention is 1-5%, which helps to improve the stability of the glass, inhibit the growth of glass precipitates, and make the size of glass precipitates smaller.

[0032] This invention employs a wet grinding process on the obtained pre-melted glass, combined with a flattening and O-forming technique, to create a steric hindrance effect and hydrophobicity on the surface of the glass particles. After drying, a sealing glass powder with uniform particle size distribution and anti-agglomeration properties is obtained. During the subsequent preparation of electroplating silver paste, the obtained sealing glass powder can be more uniformly mixed and slurried with silver powder, without any aggregation or agglomeration. The resulting glass powder has a moderate particle size, allowing for uniform mixing with silver powder without aggregation or agglomeration; the precipitated crystals have a high content, uniform dispersion, and moderate grain size, which is beneficial for improving its acid corrosion resistance and electroplating resistance.

[0033] The crystalline glass powder for electroplating silver paste obtained by this invention produces crystals of different sizes under different implementation temperatures and time conditions. Under the implementation temperature range of 800-850℃ and sintering for 5-10 minutes, the crystal size range is 50-200nm.

[0034] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0035] 1) This invention introduces crystal phase design techniques into the formation of the crystalline phase of crystalline glass powder used in electroplating silver paste, enabling the glass to precipitate uniformly distributed nano-sized microcrystals. On the one hand, the crystallization ability of the glass powder is improved by changing its composition; on the other hand, by adjusting the glass composition, ball milling conditions, and implementing temperature control, the precipitated crystals are uniformly distributed and small in size (50-200 nm) nano-microcrystals.

[0036] 2) The glass powder described in this invention can precipitate uniformly distributed nano-sized crystals during sintering and encapsulation, with the main crystalline phase being SrTi. 21 O 38 The crystal size is 50-200 nm; the uniformly distributed nano-sized crystals not only help to improve the acid corrosion resistance of crystalline glass powder for electroplating silver paste, but also delay the propagation of microcracks caused by the difference in thermal expansion coefficients between the silver electrode, glass phase, and substrate (96Al2O3 ceramic, etc.), and enhance the bonding between the silver electrode and the substrate. It is suitable for the preparation of electroplating silver paste for the surface electrode of chip resistor. Attached Figure Description

[0037] Figure 1 This is a scanning electron microscope image of the crystalline phase precipitated from the crystalline glass powder used in the electroplating silver paste obtained in Example 1.

[0038] Figure 2 This is a scanning electron microscope (SEM) image of the interface between the crystalline glass powder for electroplating silver paste obtained in Example 1 and the 96Al2O3 ceramic substrate.

[0039] Figure 3 This is a scanning electron microscope image of the crystalline phase precipitated from the crystalline glass powder used in the electroplating silver paste obtained in Example 2.

[0040] Figure 4 This is a scanning electron microscope (SEM) image of the interface between the crystalline glass powder for electroplating silver paste obtained in Example 2 and the 96Al2O3 ceramic substrate.

[0041] Figure 5 The image shows the lead wire breakage after the adhesion test of the silver electrode obtained in Example 3.

[0042] Figure 6 The image shows the silver electrode detaching after the adhesion test of the silver electrode obtained in Comparative Example 1. Detailed Implementation

[0043] The present invention will be further described in detail below through specific implementation examples. These implementation examples are based on the technology of the present invention, and detailed implementation methods and specific operating procedures are given. However, the scope of protection of the present invention is not limited to the implementation examples given below.

[0044] Example 1

[0045] A crystalline glass powder for use in electroplating silver paste, the chemical composition of its raw materials by mass percentage is: SiO2 36%, TiO2 15%, B2O3 15%, SrO 8%, MgO 8%, ZnO 8%, BaO 2%, Na2O 5%, Al2O3 3%; the specific preparation method includes the following steps:

[0046] a. Using quartz sand, boric acid, titanium dioxide, strontium carbonate, magnesium oxide, zinc oxide, barium carbonate, sodium carbonate, and aluminum oxide as raw materials, calculate the weight ratio of each raw material based on the mass percentage of the chemical composition of the crystalline glass powder used for electroplating silver paste, and weigh the corresponding raw materials.

[0047] b. After the weighed raw materials are mixed evenly, they are placed in an electric resistance furnace for melting. The furnace is kept at 1450℃ for 30 minutes. After being taken out of the furnace, the raw materials are quenched in water and dried to obtain a pre-melted glass sample.

[0048] c. Crush the pre-melted sample, disperse it with the same mass of anhydrous ethanol, and add 0.05 wt.% of Pingpingjia O as a surfactant; then ball mill it, wherein the grinding agate beads account for 50% of the mass of the resulting slurry, and ball mill at 180 r / min for 9 h; pass it through a 500 mesh sieve and dry it at 80 ℃ for 6 h; thus obtaining the glass powder for electroplating silver paste.

[0049] Testing revealed that the particle size of the obtained crystalline glass powder for electroplating silver paste was 1–5 μm, and its specific surface area was 21 m². 2 / g; its glass transition temperature is 601℃, and its coefficient of thermal expansion is 7.68×10. -6 ℃ -1(25~500℃), the mass loss due to acid erosion is 0.21wt.% (10wt.% hydrochloric acid, 60℃, 30min).

[0050] Figure 1 This is a scanning electron microscope (SEM) image of the crystalline phase precipitated after sintering the crystalline glass powder for electroplating silver paste obtained in this embodiment at 840°C for 10 min. It can be seen that the crystalline glass powder for electroplating silver paste precipitates a large number of uniformly distributed crystals (SrTi) with a size of 50–100 nm after sintering at 840°C for 10 min. 21 O 38 (crystal).

[0051] The electroplating-resistant silver paste obtained in this embodiment was co-sintered with 96Al2O3 ceramic substrate at 840℃ for 10 min using crystalline glass powder. The scanning electron microscope image of the interface of the resulting sintered sample is shown in the figure. Figure 2 As can be seen, the interface is tightly integrated.

[0052] Example 2

[0053] A crystalline glass powder for use in electroplating silver paste, the chemical composition of its raw materials by mass percentage is: SiO2 34%, TiO2 17%, B2O3 16%, SrO 7%, MgO 9%, ZnO 8%, BaO 2%, Na2O 4%, Al2O3 3%; the specific preparation method includes the following steps:

[0054] a. Using quartz sand, boric acid, titanium dioxide, strontium carbonate, magnesium oxide, zinc oxide, barium carbonate, sodium carbonate, and aluminum oxide as raw materials, calculate the weight ratio of each raw material based on the mass percentage of the chemical composition of the crystalline glass powder used for electroplating silver paste, and weigh the corresponding raw materials.

[0055] b. After the weighed raw materials are mixed evenly, they are placed in an electric resistance furnace for melting. The furnace is kept at 1400℃ for 50 minutes. After being taken out of the furnace, the raw materials are quenched in water and dried to obtain a pre-melted glass sample.

[0056] c. Crush the pre-melted sample, disperse it with the same mass of anhydrous ethanol, and add 0.06 wt.% of Pingpingjia O as a surfactant; then ball mill it, wherein the grinding agate beads account for 57% of the mass of the resulting slurry, and ball mill it for 10 h at 200 r / min; pass it through a 500 mesh sieve and dry it at 75 ℃ for 8 h; thus obtaining the glass powder for electroplating silver paste.

[0057] Testing revealed that the obtained crystalline glass powder for electroplating silver paste has a particle size of <5μm and a specific surface area of ​​26m². 2 / g; its glass transition temperature is 596℃, and its coefficient of thermal expansion is 7.96×10. -6 ℃ -1(25~500℃), the mass loss due to acid erosion is 0.32% (10wt.% hydrochloric acid, 60℃, 30min).

[0058] Figure 3 This is a scanning electron microscope (SEM) image of the crystalline phase precipitated after sintering the crystalline glass powder for electroplating silver paste obtained in this embodiment at 850°C for 10 min. It can be seen that after sintering at 850°C for 10 min, the obtained crystalline glass powder for electroplating silver paste precipitates a large number of uniformly distributed crystals (SrTi) with a size of 50–200 nm. 21 O 38 (crystal).

[0059] The electroplating-resistant silver paste obtained in this embodiment was further co-sintered with a 96Al2O3 ceramic substrate at 850°C for 10 min using crystalline glass powder. Scanning electron microscope images of the interface of the resulting sintered sample were obtained. Figure 4 As can be seen, the interface is tightly integrated.

[0060] Example 3

[0061] A crystalline glass powder for use in electroplating silver paste, the chemical composition of its raw materials by mass percentage is: SiO2 38%, TiO2 14%, B2O3 18%, SrO 9%, MgO 6%, ZnO 6%, BaO 3%, Na2O 4%, Al2O3 2%; the specific preparation method includes the following steps:

[0062] a. Using quartz sand, boric acid, titanium dioxide, strontium carbonate, magnesium oxide, zinc oxide, barium carbonate, sodium carbonate, and aluminum oxide as raw materials, calculate the weight ratio of each raw material based on the mass percentage of the chemical composition of the crystalline glass powder used for electroplating silver paste, and weigh the corresponding raw materials.

[0063] b. After the weighed raw materials are mixed evenly, they are placed in an electric resistance furnace for melting. The furnace is kept at 1400℃ for 80 minutes. After being taken out of the furnace, the raw materials are quenched in water and dried to obtain a pre-melted glass sample.

[0064] c. Crush the pre-melted sample, disperse it with the same mass of anhydrous ethanol, and add 0.08 wt.% of Pingpingjia O as a surfactant; then ball mill it, wherein the grinding agate beads account for 58 wt.% of the mass of the resulting slurry, and ball mill at 280 r / min for 9 h; pass it through a 500 mesh sieve and dry it at 80 ℃ for 6 h; thus obtaining the glass powder for electroplating silver paste.

[0065] Testing revealed that the obtained crystalline glass powder for electroplating silver paste has a particle size <5μm (D50) and a specific surface area of ​​20m². 2 / g; its glass transition temperature is 607℃, and its coefficient of thermal expansion is 7.47×10. -6 ℃ -1(25~500℃), the mass loss due to acid erosion is 0.25% (10wt.% hydrochloric acid, 60℃, 30min);

[0066] Application examples

[0067] The electroplating-resistant silver paste described in Example 1 was prepared into a silver electronic paste using crystalline glass powder. After rolling, screen printing, sintering, and electroplating, a silver electrode was obtained attached to a 96Al2O3 ceramic substrate. The specific preparation steps included:

[0068] 1) The electroplating resistant silver paste obtained in Example 1 was mixed evenly with crystalline glass powder, silver powder, terpineol, ethyl cellulose, and diethylene glycol butyl ether to obtain a silver electronic paste. The silver powder was commercially available silver powder with a particle size of 2.51 μm (D50; bulk density 4.10 kg / m³). 3 Specific surface area 0.46m² 2 / g) and particle size 0.98μm (D50; bulk density 3.60kg / m³) 3 Specific surface area 1.28m² 2 The silver paste is made by mixing two types of spherical silver powders (g) at a mass ratio of 1:4; the mass ratio of different components of the silver paste is as follows: silver powder 77%, terpineol 16.8%, ethyl cellulose 2%, diethylene glycol butyl ether 1.2%, and sealing glass powder 3%.

[0069] 2) The obtained electroplating resistant silver paste was screen-printed onto the surface of a 96Al2O3 ceramic substrate, and then sintered under nitrogen and 850℃ for 10 min; the resulting silver electrode has a size of 2mm×2mm.

[0070] The adhesion strength of the silver electrodes was tested using industry standards. During the test, the leads of all silver electrode samples (≥12 samples) broke, indicating that the adhesion strength of the silver electrodes exceeded the breaking strength of the leads. According to the test results, the adhesion force of a 2mm × 2mm silver electrode is >12kgf, and its adhesion strength is >300kgf / cm². 2 The silver paste, made from crystalline glass powder, exhibits excellent electroplating resistance. After electroplating, the adhesion strength of the silver electrode far exceeds industry standards (currently, the industry standard for a 2mm × 2mm silver electrode is >3 kgf adhesion and >75 kgf / cm²). 2 ).like Figure 5 The image shown is an image of the lead wire breaking after the silver electrode adhesion test in this embodiment.

[0071] Comparative Example 1

[0072] A crystalline glass powder for silver paste, the chemical composition of its raw materials by mass percentage is: SiO2 38%, TiO2 3%, B2O3 15%, SrO 10%, MgO 10%, ZnO 10%, BaO 4%, Na2O 5%, Al2O3 5%; the specific preparation method includes the following steps:

[0073] a. Using quartz sand, boric acid, titanium dioxide, strontium carbonate, magnesium oxide, zinc oxide, barium carbonate, sodium carbonate, and aluminum oxide as raw materials, calculate the weight ratio of each raw material based on the mass percentage of the chemical composition of the crystalline glass powder used for electroplating silver paste, and weigh the corresponding raw materials.

[0074] b. After the weighed raw materials are mixed evenly, they are placed in an electric resistance furnace for melting. The furnace is kept at 1400℃ for 80 minutes. After being taken out of the furnace, the raw materials are quenched in water and dried to obtain a pre-melted glass sample.

[0075] c. Crush the pre-melted sample, disperse it with the same mass of anhydrous ethanol, add 0.08 wt.% of Pingpingjia O as a surfactant; then ball mill it, wherein the grinding agate beads account for 58 wt.% of the mass of the resulting slurry, and ball mill it for 10 h at 180 r / min; pass it through a 500 mesh sieve and dry it at 80 ℃ for 6 h; thus obtaining the sealing glass powder.

[0076] Testing revealed that the obtained sealing glass powder had a particle size <5μm (D50) and a specific surface area of ​​18m². 2 / g; its glass transition temperature is 627℃, and its coefficient of thermal expansion is 7.89×10. -6 ℃ -1 (25~500℃), the mass loss due to acid erosion is 3.25% (10wt.% hydrochloric acid, 60℃, 30min).

[0077] The sealing glass powder is made into a silver electronic paste, which is then rolled, screen printed, sintered, and electroplated to obtain a silver electrode attached to a 96Al2O3 ceramic substrate. The specific preparation steps include:

[0078] 1) The obtained sealing glass powder, silver powder, terpineol, ethyl cellulose, and diethylene glycol butyl ether are mixed evenly to obtain silver electronic paste. The silver powder is commercially available silver powder with a particle size of 2.51 μm (D50; bulk density 4.10 kg / m³). 3 Specific surface area 0.46m² 2 / g) and particle size 0.98μm (D50; bulk density 3.60kg / m³) 3 Specific surface area 1.28m² 2The silver paste is made by mixing two types of spherical silver powders (g) at a mass ratio of 1:4; the mass ratio of different components of the silver paste is 77% silver powder, 16.8% terpineol, 2% ethyl cellulose, 1.2% diethylene glycol butyl ether, and 3% sealing glass powder.

[0079] 2) The obtained electroplating resistant silver paste was screen-printed onto the surface of a 96Al2O3 ceramic substrate, and then sintered under nitrogen and 850℃ for 10 min; the resulting silver electrode has a size of 2mm×2mm.

[0080] The adhesion strength of the silver electrodes was tested using industry standards, with at least 12 silver electrode samples tested. According to the test results, the average adhesion strength of a 2mm × 2mm silver electrode was 4.66 kgf, the maximum adhesion strength was 7.42 kgf, and the minimum adhesion strength was 1.65 kgf.

[0081] The low TiO2 content in the sealing glass component described in Comparative Example 1 resulted in poor acid corrosion resistance and electroplating resistance, leading to poor adhesion strength and stability of the silver electrode.

[0082] Comparative Example 2

[0083] A crystalline glass powder for silver paste, the chemical composition of its raw materials by mass percentage is: SiO2 36%, TiO2 15%, B2O3 15%, SrO 8%, MgO 8%, ZnO 8%, BaO 2%, Na2O 5%, Al2O3 3%; the specific preparation method includes the following steps:

[0084] a. Using quartz sand, boric acid, titanium dioxide, strontium carbonate, magnesium oxide, zinc oxide, barium carbonate, sodium carbonate, and aluminum oxide as raw materials, calculate the weight ratio of each raw material based on the mass percentage of the chemical composition of the crystalline glass powder used for electroplating silver paste, and weigh the corresponding raw materials.

[0085] b. After the weighed raw materials are mixed evenly, they are placed in an electric resistance furnace for melting. The furnace is kept at 1450℃ for 30 minutes. After being taken out of the furnace, the raw materials are quenched in water and dried to obtain a pre-melted glass sample.

[0086] c. Crush the pre-melted sample, disperse it with the same mass of anhydrous ethanol, add 0.05 wt.% of Pingpingjia O as a surfactant; then ball mill it, wherein the grinding agate beads account for 50 wt.% of the mass of the resulting slurry, and ball mill at 180 r / min for 10 h; pass it through a 500 mesh sieve and dry it at 80℃ for 6 h; thus obtaining the sealing glass powder.

[0087] The sealing glass powder is made into a silver electronic paste, which is then rolled, screen printed, sintered, and electroplated to obtain a silver electrode attached to a 96Al2O3 ceramic substrate. The specific preparation steps include:

[0088] 1) The obtained sealing glass powder, silver powder, terpineol, ethyl cellulose, and diethylene glycol butyl ether are mixed evenly to obtain silver electronic paste. The silver powder is commercially available silver powder with a particle size of 2.51 μm (D50; bulk density 4.10 kg / m³). 3 Specific surface area 0.46m² 2 / g) and particle size 0.98μm (D50; bulk density 3.60kg / m³) 3 Specific surface area 1.28m² 2 The silver paste is made by mixing two types of spherical silver powders (g) at a mass ratio of 1:4; the mass ratio of different components of the silver paste is 77% silver powder, 16.8% terpineol, 2% ethyl cellulose, 1.2% diethylene glycol butyl ether, and 3% sealing glass powder.

[0089] 2) The obtained silver paste was screen-printed onto the surface of a 96Al2O3 ceramic substrate, and then sintered under nitrogen and 780℃ for 10 min; the resulting silver electrode had a size of 2mm×2mm.

[0090] The adhesion strength of the silver electrodes was tested using industry standards, with at least 12 silver electrode samples tested. According to the test results, the average adhesion strength of a 2mm × 2mm silver electrode was 6.85 kgf, the maximum adhesion strength was 8.06 kgf, and the minimum adhesion strength was 5.01 kgf. Figure 6 The image shown is an image of the silver electrode detaching after the adhesion test in this comparative example. Using the method described in Comparative Example 2, the silver electrode adhesion was low due to the mismatch between the operating temperature and the glass.

[0091] Comparative Example 3

[0092] A crystalline glass powder for silver paste, the chemical composition of its raw materials by mass percentage is: SiO2 36%, TiO2 15%, B2O3 15%, SrO 8%, MgO 8%, ZnO 8%, BaO 2%, Na2O 5%, Al2O3 3%; the specific preparation method includes the following steps:

[0093] a. Using quartz sand, boric acid, titanium dioxide, strontium carbonate, magnesium oxide, zinc oxide, barium carbonate, sodium carbonate, and aluminum oxide as raw materials, calculate the weight ratio of each raw material based on the mass percentage of the chemical composition of the crystalline glass powder used for electroplating silver paste, and weigh the corresponding raw materials.

[0094] b. After the weighed raw materials are mixed evenly, they are placed in an electric resistance furnace for melting. The furnace is kept at 1450℃ for 30 minutes. After being taken out of the furnace, the raw materials are quenched in water and dried to obtain a pre-melted glass sample.

[0095] c. Crush the pre-melted sample, disperse it with the same mass of anhydrous ethanol, add 0.05 wt.% of the pre-melted glass sample, and add Span-85 as a surfactant; then ball mill it, wherein the grinding agate beads account for 50 wt.% of the mass of the resulting slurry, and ball mill at 180 r / min for 9 h; pass it through a 500 mesh sieve and dry it at 80 °C for 6 h; thus obtaining the sealing glass powder.

[0096] The sealing glass powder is made into a silver electronic paste, which is then rolled, screen printed, sintered, and electroplated to obtain a silver electrode attached to a 96Al2O3 ceramic substrate. The specific preparation steps include:

[0097] 1) The obtained sealing glass powder, silver powder, terpineol, ethyl cellulose, and diethylene glycol butyl ether are mixed evenly to obtain silver electronic paste. The silver powder is commercial silver powder, which is a mixture of two types of spherical silver powder with a particle size of 2.51 μm (D50) and 0.98 μm (D50) in a mass ratio of 1:4. The mass ratio of different components of the silver paste is 77% silver powder, 16.8% terpineol, 2% ethyl cellulose, 1.2% diethylene glycol butyl ether, and 3% sealing glass powder.

[0098] 2) The obtained silver paste was screen-printed onto the surface of a 96Al2O3 ceramic substrate, and then sintered under nitrogen and 850℃ for 10 min; the resulting silver electrode had a size of 2mm×2mm.

[0099] The adhesion strength of the silver electrodes was tested using industry standards, with at least 12 silver electrode samples tested. According to the test results, the average adhesion strength of the 2mm × 2mm silver electrode was 2.87 kgf, the maximum adhesion strength was 5.13 kgf, and the minimum adhesion strength was 0.98 kgf. Using the method described in Comparative Example 3, the glass phase dispersion after sintering was poor, resulting in silver electrodes with low adhesion and poor stability.

[0100] Comparative Example 4

[0101] A crystalline glass powder for use in electroplating silver paste, the chemical composition of its raw materials by mass percentage is: SiO2 40%, TiO2 10%, B2O3 20%, SrO 9%, MgO 6%, ZnO 6%, BaO 3%, Na2O 4%, Al2O3 2%; the specific preparation method includes the following steps:

[0102] a. Using quartz sand, boric acid, titanium dioxide, strontium carbonate, magnesium oxide, zinc oxide, barium carbonate, sodium carbonate, and aluminum oxide as raw materials, calculate the weight ratio of each raw material based on the mass percentage of the chemical composition of the crystalline glass powder used for electroplating silver paste, and weigh the corresponding raw materials.

[0103] b. After the weighed raw materials are mixed evenly, they are placed in an electric resistance furnace for melting. The furnace is kept at 1400℃ for 80 minutes. After being taken out of the furnace, the raw materials are quenched in water and dried to obtain a pre-melted glass sample.

[0104] c. Crush the pre-melted sample, disperse it with the same mass of anhydrous ethanol, and add 0.08 wt.% of Pingpingjia O as a surfactant; then ball mill it, wherein the grinding agate beads account for 58 wt.% of the mass of the resulting slurry, and ball mill it for 10 h at 280 r / min; pass it through a 500 mesh sieve and dry it at 80 ℃ for 6 h; thus obtaining the glass powder for electroplating silver paste.

[0105] The electroplating-resistant silver paste described in Comparative Example 4 was used to prepare a silver electronic paste using crystalline glass powder. After rolling, screen printing, sintering, and electroplating, a silver electrode was obtained attached to a 96Al2O3 ceramic substrate. The specific preparation steps included:

[0106] 1) The electroplating resistant silver paste obtained in this comparative example was mixed evenly with crystalline glass powder, silver powder, terpineol, ethyl cellulose, and diethylene glycol butyl ether to obtain a silver electronic paste. The silver powder was commercially available silver powder with a particle size of 2.51 μm (D50; bulk density 4.10 kg / m³). 3 Specific surface area 0.46m² 2 / g) and particle size 0.98μm (D50; bulk density 3.60kg / m³) 3 Specific surface area 1.28m² 2 The silver paste is made by mixing two types of spherical silver powders (g) at a mass ratio of 1:4; the mass ratio of different components of the silver paste is as follows: silver powder 77%, terpineol 16.8%, ethyl cellulose 2%, diethylene glycol butyl ether 1.2%, and sealing glass powder 3%.

[0107] 2) The obtained electroplating resistant silver paste was screen-printed onto the surface of a 96Al2O3 ceramic substrate, and then sintered under nitrogen and 850℃ for 10 min; the resulting silver electrode has a size of 2mm×2mm.

[0108] The adhesion strength of the silver electrodes was tested using industry standards. During the test, the leads of all silver electrode samples (≥12 samples) broke, indicating that the adhesion strength of the silver electrodes exceeded the breaking strength of the leads. According to the test results, the average adhesion strength of the silver electrodes was 1.98 kgf, the maximum adhesion strength was 3.86 kgf, and the minimum adhesion strength was 0.67 kgf. Using the method described in Comparative Example 4, the poor chemical stability of the sintered glass resulted in poor electroplating resistance and low adhesion of the silver electrodes after electroplating.

[0109] Table 1 compares the adhesion of the silver electrode after sintering the silver paste in the application example with that in the comparative example.

[0110] Application examples Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Maximum adhesion Lead wire breakage (>12 kgf) 7.42 kgf 8.06 kgf 5.13 kgf 3.86 kgf Minimum adhesion Lead wire breakage (>12 kgf) 1.65 kgf 5.01 kgf 0.98kgf 0.67kgf Average adhesion Lead wire breakage (>12 kgf) 4.66 kgf 6.85 kgf 2.87 kgf 1.98kgf

[0111] This invention is not limited to the embodiments described above. Those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications are also considered within the scope of protection of this invention. Contents not described in detail in this specification are prior art known to those skilled in the art.

Claims

1. An electroplating silver paste based on glass powder for electroplating silver paste, characterized in that, It includes glass powder, silver powder, and organic carrier. The raw materials and their mass percentages are as follows: 2-5% glass powder for electroplating silver paste, 70-80% silver powder, and 15-25% organic carrier. The glass powder used for electroplating silver paste has the following chemical composition by mass percentage: SiO2 30~40%, TiO2 14~18%, B2O3 10~20%, SrO 5~10%, MgO 5~10%, ZnO 5~10%, BaO 1~3%, Na2O 2~8%, Al2O3 1~5%; the TiO2 / B2O3 ratio is in the range of 0.66~1.

50. The glass powder can precipitate uniformly distributed nano-sized crystals during sintering and encapsulation, with the main crystalline phase being SrTi. 21 O 38 The crystal size is 50~200nm; The preparation method of the glass powder for electroplating silver paste includes the following steps: 1) Weigh each raw material according to the ratio, mix the raw materials evenly, melt at high temperature, quench in water, and dry to obtain a pre-melted glass sample; 2) The obtained pre-melted glass sample was crushed, ball-milled, dried, and sieved to obtain glass powder resistant to electroplating silver paste; Step 2) The ball milling step adopts a wet milling process and introduces Pingpingjia O as an additive; the ball milling parameters used are 180~360 r / min, and the milling time is 8~10h; The silver powder includes at least two of the following spherical silver powders: spherical silver powder 1, with a median particle size of 2-3 μm; spherical silver powder 2, with a median particle size of 0.8-1.2 μm; and spherical silver powder 3, with a median particle size of 0.5-0.8 μm. When electroplating-resistant silver paste is applied to the preparation of silver electrodes, its adhesion is >12 kgf and its adhesion strength is >300 kgf / cm. 2 .

2. The electroplating resistant silver paste according to claim 1, characterized in that, The chemical composition of the glass powder used for electroplating silver paste, by mass percentage, includes: SiO2 35~38%, TiO2 14~18%, B2O3 12~18%, SrO 6~10%, MgO 6~10%, ZnO 7~10%, BaO 1~3%, Na2O 2~6%, and Al2O3 2~4%.

3. The electroplating resistant silver paste according to claim 1, characterized in that, The glass powder used in the electroplating silver paste has a glass transition temperature of 580~620℃ and a coefficient of thermal expansion of 7.40×10⁻⁶. -6 ~8.50×10 -6 ℃ -1 The mass loss due to acid erosion is <0.50wt%.

4. The electroplating resistant silver paste according to claim 1, characterized in that, The high-temperature melting step uses a temperature of 1350~1450 ℃ and a holding time of 30~80 min.

5. The electroplating resistant silver paste according to claim 1, characterized in that, The amount of O added to the pre-melted glass sample is 0.05~0.1% of the sample mass.

6. The electroplating resistant silver paste according to claim 1, characterized in that, The glass powder obtained by sieving for use in electroplating silver paste has a D50 of <5μm and a specific surface area of ​​20~26 m². 2 / g.

7. The electroplating resistant silver paste according to claim 1, characterized in that, The spherical silver powder 1 has a bulk density of 3.8~4.5 kg / m³. 3 Specific surface area 0.3~0.6m² 2 / g; spherical silver powder 2, bulk density 3.2~3.8kg / m³ 3 Specific surface area: 0.8~1.5m² 2 / g; spherical silver powder 3, bulk density 2.8~3.0 kg / m³ 3 Specific surface area: 1.6~2.0 m² 2 / g.

8. The electroplating resistant silver paste according to claim 1, characterized in that, The organic carrier includes at least one of terpineol, ethyl cellulose, and diethylene glycol butyl ether.

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