CN117198588A - High-temperature conductive silver paste for microcrystalline glass thick film heating plate, and preparation method and sintering process thereof - Google Patents
High-temperature conductive silver paste for microcrystalline glass thick film heating plate, and preparation method and sintering process thereof Download PDFInfo
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- CN117198588A CN117198588A CN202210808740.2A CN202210808740A CN117198588A CN 117198588 A CN117198588 A CN 117198588A CN 202210808740 A CN202210808740 A CN 202210808740A CN 117198588 A CN117198588 A CN 117198588A
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- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 title claims abstract description 121
- 239000011521 glass Substances 0.000 title claims abstract description 116
- 238000005245 sintering Methods 0.000 title claims abstract description 78
- 238000010438 heat treatment Methods 0.000 title claims abstract description 58
- 238000000034 method Methods 0.000 title claims abstract description 39
- 230000008569 process Effects 0.000 title claims abstract description 32
- 238000002360 preparation method Methods 0.000 title abstract description 14
- 239000000843 powder Substances 0.000 claims abstract description 69
- 239000002241 glass-ceramic Substances 0.000 claims abstract description 64
- 239000002131 composite material Substances 0.000 claims abstract description 48
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical group O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 30
- 239000000377 silicon dioxide Substances 0.000 claims abstract description 11
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims abstract description 9
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 claims abstract description 9
- KGBXLFKZBHKPEV-UHFFFAOYSA-N boric acid Chemical compound OB(O)O KGBXLFKZBHKPEV-UHFFFAOYSA-N 0.000 claims abstract description 8
- 239000004327 boric acid Substances 0.000 claims abstract description 8
- 229910052814 silicon oxide Inorganic materials 0.000 claims abstract description 8
- 239000000395 magnesium oxide Substances 0.000 claims abstract description 5
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 claims abstract description 5
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 claims abstract description 5
- 239000000758 substrate Substances 0.000 claims description 33
- 239000002245 particle Substances 0.000 claims description 27
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 9
- -1 alcohol ester Chemical class 0.000 claims description 9
- 238000002156 mixing Methods 0.000 claims description 9
- 238000007639 printing Methods 0.000 claims description 9
- 229910052710 silicon Inorganic materials 0.000 claims description 9
- 239000010703 silicon Substances 0.000 claims description 9
- 239000002904 solvent Substances 0.000 claims description 9
- ZFOZVQLOBQUTQQ-UHFFFAOYSA-N Tributyl citrate Chemical compound CCCCOC(=O)CC(O)(C(=O)OCCCC)CC(=O)OCCCC ZFOZVQLOBQUTQQ-UHFFFAOYSA-N 0.000 claims description 8
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 8
- 238000003723 Smelting Methods 0.000 claims description 7
- RVTZCBVAJQQJTK-UHFFFAOYSA-N oxygen(2-);zirconium(4+) Chemical compound [O-2].[O-2].[Zr+4] RVTZCBVAJQQJTK-UHFFFAOYSA-N 0.000 claims description 6
- 229910001928 zirconium oxide Inorganic materials 0.000 claims description 6
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 claims description 5
- 239000000126 substance Substances 0.000 claims description 5
- VXQBJTKSVGFQOL-UHFFFAOYSA-N 2-(2-butoxyethoxy)ethyl acetate Chemical compound CCCCOCCOCCOC(C)=O VXQBJTKSVGFQOL-UHFFFAOYSA-N 0.000 claims description 4
- QCDWFXQBSFUVSP-UHFFFAOYSA-N 2-phenoxyethanol Chemical compound OCCOC1=CC=CC=C1 QCDWFXQBSFUVSP-UHFFFAOYSA-N 0.000 claims description 4
- 239000001856 Ethyl cellulose Substances 0.000 claims description 4
- ZZSNKZQZMQGXPY-UHFFFAOYSA-N Ethyl cellulose Chemical compound CCOCC1OC(OC)C(OCC)C(OCC)C1OC1C(O)C(O)C(OC)C(CO)O1 ZZSNKZQZMQGXPY-UHFFFAOYSA-N 0.000 claims description 4
- QYMFNZIUDRQRSA-UHFFFAOYSA-N dimethyl butanedioate;dimethyl hexanedioate;dimethyl pentanedioate Chemical compound COC(=O)CCC(=O)OC.COC(=O)CCCC(=O)OC.COC(=O)CCCCC(=O)OC QYMFNZIUDRQRSA-UHFFFAOYSA-N 0.000 claims description 4
- 238000001035 drying Methods 0.000 claims description 4
- 229920001249 ethyl cellulose Polymers 0.000 claims description 4
- 235000019325 ethyl cellulose Nutrition 0.000 claims description 4
- 229920000728 polyester Polymers 0.000 claims description 4
- 238000000498 ball milling Methods 0.000 claims description 3
- 238000010791 quenching Methods 0.000 claims description 3
- 230000000171 quenching effect Effects 0.000 claims description 3
- 238000005096 rolling process Methods 0.000 claims description 3
- 235000012239 silicon dioxide Nutrition 0.000 claims description 3
- 239000010935 stainless steel Substances 0.000 claims description 3
- 229910001220 stainless steel Inorganic materials 0.000 claims description 3
- 239000000853 adhesive Substances 0.000 abstract description 16
- 230000001070 adhesive effect Effects 0.000 abstract description 16
- 238000010304 firing Methods 0.000 abstract description 7
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 abstract description 6
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 abstract description 6
- 239000004020 conductor Substances 0.000 description 53
- 239000010410 layer Substances 0.000 description 47
- 239000012071 phase Substances 0.000 description 30
- 230000000052 comparative effect Effects 0.000 description 28
- 238000003466 welding Methods 0.000 description 23
- 229910052709 silver Inorganic materials 0.000 description 15
- 239000004332 silver Substances 0.000 description 15
- 238000012360 testing method Methods 0.000 description 14
- 238000009792 diffusion process Methods 0.000 description 11
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 8
- 238000005336 cracking Methods 0.000 description 8
- 239000002002 slurry Substances 0.000 description 8
- 229910000679 solder Inorganic materials 0.000 description 8
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 7
- 239000007790 solid phase Substances 0.000 description 7
- 238000005538 encapsulation Methods 0.000 description 6
- 238000005187 foaming Methods 0.000 description 5
- 238000004519 manufacturing process Methods 0.000 description 5
- 239000000047 product Substances 0.000 description 5
- QVQLCTNNEUAWMS-UHFFFAOYSA-N barium oxide Chemical compound [Ba]=O QVQLCTNNEUAWMS-UHFFFAOYSA-N 0.000 description 4
- 230000009286 beneficial effect Effects 0.000 description 4
- 238000002844 melting Methods 0.000 description 4
- IATRAKWUXMZMIY-UHFFFAOYSA-N strontium oxide Chemical compound [O-2].[Sr+2] IATRAKWUXMZMIY-UHFFFAOYSA-N 0.000 description 4
- 230000008646 thermal stress Effects 0.000 description 4
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 230000007547 defect Effects 0.000 description 3
- 238000000280 densification Methods 0.000 description 3
- 239000012530 fluid Substances 0.000 description 3
- 239000007791 liquid phase Substances 0.000 description 3
- 230000008018 melting Effects 0.000 description 3
- 229910052697 platinum Inorganic materials 0.000 description 3
- 239000011347 resin Substances 0.000 description 3
- 229920005989 resin Polymers 0.000 description 3
- 239000004902 Softening Agent Substances 0.000 description 2
- 230000009471 action Effects 0.000 description 2
- 239000007864 aqueous solution Substances 0.000 description 2
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 description 2
- 239000000292 calcium oxide Substances 0.000 description 2
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 2
- 239000000919 ceramic Substances 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 230000002349 favourable effect Effects 0.000 description 2
- 238000009689 gas atomisation Methods 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000000149 penetrating effect Effects 0.000 description 2
- 238000004321 preservation Methods 0.000 description 2
- 230000036632 reaction speed Effects 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 230000035939 shock Effects 0.000 description 2
- SQGYOTSLMSWVJD-UHFFFAOYSA-N silver(1+) nitrate Chemical compound [Ag+].[O-]N(=O)=O SQGYOTSLMSWVJD-UHFFFAOYSA-N 0.000 description 2
- 238000010146 3D printing Methods 0.000 description 1
- 229910018125 Al-Si Inorganic materials 0.000 description 1
- 229910018520 Al—Si Inorganic materials 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 1
- 229910001128 Sn alloy Inorganic materials 0.000 description 1
- IHWJXGQYRBHUIF-UHFFFAOYSA-N [Ag].[Pt] Chemical compound [Ag].[Pt] IHWJXGQYRBHUIF-UHFFFAOYSA-N 0.000 description 1
- QCEUXSAXTBNJGO-UHFFFAOYSA-N [Ag].[Sn] Chemical compound [Ag].[Sn] QCEUXSAXTBNJGO-UHFFFAOYSA-N 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 230000002238 attenuated effect Effects 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 239000000969 carrier Substances 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- CLOMYZFHNHFSIQ-UHFFFAOYSA-N clonixin Chemical compound CC1=C(Cl)C=CC=C1NC1=NC=CC=C1C(O)=O CLOMYZFHNHFSIQ-UHFFFAOYSA-N 0.000 description 1
- 230000001276 controlling effect Effects 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 238000002788 crimping Methods 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000007598 dipping method Methods 0.000 description 1
- 239000002270 dispersing agent Substances 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 230000036541 health Effects 0.000 description 1
- 230000003116 impacting effect Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000011068 loading method Methods 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 239000011777 magnesium Substances 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 229910052763 palladium Inorganic materials 0.000 description 1
- SWELZOZIOHGSPA-UHFFFAOYSA-N palladium silver Chemical compound [Pd].[Ag] SWELZOZIOHGSPA-UHFFFAOYSA-N 0.000 description 1
- 239000012466 permeate Substances 0.000 description 1
- 229920002635 polyurethane Polymers 0.000 description 1
- 239000004814 polyurethane Substances 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 238000007650 screen-printing Methods 0.000 description 1
- 229910021487 silica fume Inorganic materials 0.000 description 1
- 239000005368 silicate glass Substances 0.000 description 1
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 1
- 229910010271 silicon carbide Inorganic materials 0.000 description 1
- 229910001961 silver nitrate Inorganic materials 0.000 description 1
- 238000004088 simulation Methods 0.000 description 1
- 238000003746 solid phase reaction Methods 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 230000035882 stress Effects 0.000 description 1
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- 230000003746 surface roughness Effects 0.000 description 1
- 230000002195 synergetic effect Effects 0.000 description 1
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Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B30/00—Energy efficient heating, ventilation or air conditioning [HVAC]
Landscapes
- Conductive Materials (AREA)
Abstract
The invention provides a high-temperature conductive silver paste for a glass ceramic thick film heating plate, a preparation method and a sintering process thereof, wherein the high-temperature conductive silver paste for the glass ceramic thick film heating plate comprises the following silver powder in percentage by mass: 75-85%; composite glass powder: 1 to 5 percent; organic carrier: 10-24%; the composite glass powder comprises a component A and a component B in a mass ratio of 1-3:1, wherein the component B is silica micropowder, and the component A comprises silicon oxide in percentage by mass: 35-50%; boric acid: 20-30%; 10-15% of magnesium oxide; alumina: 5-10%; titanium oxide: 3-5%; zirconia: 1 to 2 percent. The glass ceramic thick film heating plate prepared by the invention has high weldability, strong adhesive force, high current impact resistance, high re-firing stability and excellent overall performance, and the highest working temperature can reach more than 450 ℃.
Description
Technical Field
The invention relates to the technical field of conductive silver paste, in particular to high-temperature conductive silver paste for a glass ceramic thick film heating plate, a preparation method and a sintering process thereof.
Background
The microcrystalline glass substrate has high strength, light weight, high insulating strength, good weather resistance and durability, good corrosion resistance and high cost performance, is suitable for mass production, and is especially bright and clean in surface, low in thermal expansion coefficient and strong in thermal shock resistance. The microcrystalline glass substrate thick film circuit is manufactured on the surface of microcrystalline glass by using the characteristics of a microcrystalline glass plate through a thick film process, has incomparable advantages of high thermal response speed, small volume, environmental protection, energy saving, cleanness, sanitation and the like, and is widely applied to health preserving kettles, baking plates, medical and industrial electric appliances and has rapid market development.
And printing resistor paste, conductor paste and encapsulation paste on the glass substrate by adopting a silk screen printing process. The thick film resistor layer is formed after the resistor paste is sintered at high temperature, so as to play a role in heating; the conductor paste forms a thick film conductor layer after high-temperature sintering, plays a role of an electrode or a bonding pad, and is connected with a power supply in a welding or mechanical crimping mode; the encapsulation slurry is sintered at high temperature to form a glass encapsulation layer on the surfaces of the resistor layer and the conductor layer, which mainly plays a role in isolating water and air and ensures that the resistor layer and the conductor layer are not oxidized or corroded.
In the manufacturing process of the microcrystalline glass substrate thick film heating plate, the first step is to print conductive silver paste, and then sinter the conductive silver paste into a thick film conductor at 850 ℃; the second step is to print the resistor paste and then sinter the resistor paste into a thick film resistor layer at 850 ℃; the third step is to print the encapsulation paste and sinter it into a thick film encapsulation layer at 600 ℃. The conductive layer needs to have a certain overlap with the resistive layer to form a circuit with a certain power. The encapsulation layer needs to overlie the conductor layer and the resistive layer, and there is also a lapped interface.
The microcrystalline glass substrate has a small thermal expansion coefficient, and is generally only 0 to 0.5 x 10 -6 and/C. The conductor slurry has several kinds of pure silver conductor, silver-palladium conductor, silver-platinum conductor, etc. and its important components are various metal powder or machine alloy powder of silver, palladium, platinum, etc. a small quantity of glass powder and organic carrier. Since the thermal expansion coefficient of metallic silver is generally 19.5×10 -6 There is a large thermal expansion difference between the heat-insulating layer and the microcrystalline plate. Therefore, the conductor paste is prepared on the glass ceramic plate, and defects such as foaming and cracking due to thermal expansion mismatch are extremely likely to occur. The problem of mismatch of thermal expansion of the microcrystalline substrate and the conductive silver paste can be relieved to a certain extent by adding glass frit with low thermal expansion coefficient, but the problem is difficult to solve fundamentally. And because of the high difficulty in preparing glass with low thermal expansion coefficient, a deep theoretical basis and practical experience are required.
Through many years of research, commercial medium-temperature microcrystalline glass conductor slurry is available on the market, and is characterized in that the sintering temperature is generally about 500 ℃, and the medium-temperature microcrystalline glass conductor slurry is characterized in that low-melting glass powder with the softening temperature of 420-430 ℃ and microcrystalline silver powder with high specific surface area are adopted, because the glass powder with higher softening temperature is not easy to soften at 500 ℃, and the bonding effect of tensioning the silver powder and a substrate cannot be achieved. However, once the working temperature reaches more than 300 ℃, the inside of the conductive silver layer is rearranged under the action of heat, and the glass bonding phase continues to extend deeper into the contact interface of the glass ceramic plate, so that more microcracks are generated at the interface, and finally the power of the glass ceramic thick film heating plate is attenuated to cause failure.
For the most commonly used substrate of the thick film heating element, namely the alumina ceramic substrate, the preparation method has low difficulty in meeting the application requirements, namely the technical requirements of appearance, weldability, welding resistance, adhesive force and the like. Because the coefficient of thermal expansion of alumina ceramics is about 7.2 x 10-6/°c, it is easily matched to thick film pastes. While the low thermal expansion characteristics of a glass-ceramic substrate give it good thermal stability, it presents challenges for a series of thick film pastes that match it. When the conventional high-temperature conductive silver paste is applied to a microcrystalline substrate, cracking, foaming and falling are often caused due to mismatching of thermal expansion, or open circuit is generated in a multi-period sintering process necessary for a thick film element, or obvious power attenuation occurs to the thick film element through multiple current shocks in the testing and service processes. Therefore, a novel technology of high-temperature conductive silver paste of a glass ceramic thick film heating plate is urgently needed in the industry.
Disclosure of Invention
In order to solve the appearance defects of cracking, foaming, falling and the like of the conductor paste of the glass ceramic thick film heating plate under the high-temperature preparation condition, and the problems of broken circuit, broken joint between a conductive layer and a resistance layer, poor weldability, reduced adhesive force and the like of the conductor paste under the multi-sintering-period preparation condition, the invention provides the high-temperature conductive silver paste of the glass ceramic heating plate.
The invention provides a high-temperature conductive silver paste for a glass ceramic thick film heating plate, which comprises the following components in percentage by mass
Silver powder: 75-85%; composite glass powder: 1 to 5 percent; organic carrier: 10-24%;
the composite glass powder comprises a component A and a component B in a mass ratio of 1-3:1;
the component B is silicon micropowder or similar substances with high melting point characteristics such as aluminum oxide, titanium oxide, zirconium oxide, silicon carbide and the like,
the component A comprises, by mass, 35-50% of silicon oxide, 20-30% of boric acid, 10-15% of magnesium oxide, 5-10% of aluminum oxide, 3-5% of titanium oxide and 1-2% of zirconium oxide.
Further, the silver powder is spherical, has an average particle diameter of 1.5-3 microns, a tap density of 4.5-6.5 g/ml and a specific surface area of 0.4-0.7 m 2 /g。
Further, the silicon micropowder comprises silicon dioxide with the purity of 99.9 percent and the average grain diameter of 0.5 to 1 micron; the maximum particle size is not more than 2 microns.
Further, the thermal expansion coefficient of the composite glass powder is 2.8 x 10 -6 The softening point is 755-762 ℃, the D50 is 0.8-1.3 microns, and the D99 is less than 10 microns.
Further, the organic carrier comprises the following components in percentage by mass: 30-40% of alcohol ester, 10-20% of tributyl citrate, 10-20% of dibasic ester, 5-10% of butyl carbitol acetate, 5-10% of ethylene glycol phenyl ether and 1003-6% of ethyl cellulose Dow chemical STD; the components are decocted in water bath at 80 ℃ for 4-6 hours to form uniform transparent solvent, and the transparent solvent is filtered by a 300-mesh polyester net to prepare the product.
Further, the viscosity of the conductive silver paste is 140-180 Pa.s, and the fineness is not more than 15 micrometers.
The invention also provides a preparation method of the high-temperature conductive silver paste for the glass ceramic thick film heating plate, which comprises the following steps:
1) Firstly, uniformly mixing the component A in the composite glass powder by using a mixer, smelting in a high-temperature smelting furnace by using a platinum crucible, preserving heat for 15 minutes at 300 ℃, heating to 900 ℃, preserving heat for 15 minutes, heating to 1550 ℃, preserving heat for 1 hour, and quenching by water;
4) Mixing the component A and the component B in proportion, ball milling to obtain glass ceramic composite glass powder with low thermal expansion coefficient and high softening point, wherein the thermal expansion coefficient of the composite glass powder is 2.8x10 -6 At a temperature of between 755 and 762 ℃, D50 of between 0.8 and 1.3 microns, D99 of less than 10 microns, and glass powder specific gravity of 2.2g/mm 3 ；
5) Uniformly mixing the composite glass powder, silver powder and an organic carrier in a centrifugal deaerating machine at the speed of 1200 revolutions per minute, and rolling for 5-6 times by a three-roller mill to obtain high-temperature conductive silver paste of a glass ceramic thick film heating plate, wherein the viscosity is 140-180 Pa.s; the fineness is not more than 15 micrometers.
The invention also provides a sintering process of the high-temperature conductive silver paste of the glass ceramic heating plate, which comprises the following steps: printing the high-temperature conductive silver paste on the surface of the glass ceramic thick film heating substrate by using a 200-250-mesh stainless steel composite screen, sequentially drying at 150 ℃ for 6-8 minutes, and finally sintering for 4-6 minutes at the peak sintering temperature of 800-850 ℃ under a mesh belt sintering furnace through which dry air is introduced, wherein the time from one end of the sintering furnace to the completion of sintering of a sample piece from the other end is 28-32 minutes, and forming a conductive layer on the surface of the glass ceramic heating substrate. The conductive layer is silvery white in color, compact and smooth in surface, free from foaming and cracking, and free from degradation of main properties such as weldability and adhesive force after being subjected to multi-high-temperature re-firing.
In principle, the sintering process is a densification process of various slurry powders under the action of heat. The sintering of thick film pastes is essentially a thermal unbalanced sintering, mostly based on solid phase diffusion reactions. Different sintering curves are set according to different mesh belt sintering furnaces, so that a stable and repeatable sintering environment is provided for the glass ceramic thick film heating plate. The heating rate and the cooling rate are naturally important, but the most important are the peak sintering temperature (i.e. the highest sintering temperature) and the peak holding time (i.e. the holding time at the highest sintering temperature), which have a very critical influence on the performance of the conductive layer. And correspondingly adjusting according to the different sizes of the sintered workpieces. The larger the workpiece, the higher the corresponding peak sintering temperature and the longer the hold time. Compared with the common thick film sintering process, the sintering process has the characteristics of shorter time and faster belt speed. By adopting the rapid sintering process, the diffusion depth of the glass bonding phase to the microcrystalline glass is effectively controlled by reducing the diffusion time of the glass bonding phase to the interface of the microcrystalline glass, the stress of the conductive layer and the microcrystalline glass is correspondingly reduced, and the proper diffusion depth is also beneficial to improving the current impact resistance of the conductive film.
In this rapid sintering process, there are three main components in the conductor paste, namely, a functional phase (e.g., silver powder, palladium powder, platinum powder, nickel powder, etc.), a binder phase (e.g., silicate glass, oxide, additive, etc.), and an organic vehicle (a mixture of resin and solvent). In the drying process at 150 ℃, the organic solvent in the organic carrier is basically volatilized, but most of the resin exists in the dried film, and the effect of fixing and connecting the powder is achieved. Under the condition of about 500 ℃, the resin of the conductor paste is basically volatilized. At about 750 ℃, the glass phase in the conductor slurry begins to soften, on one hand, the silver powder particles are tensioned to enable the silver powder particles to mutually generate solid-phase diffusion, and the pores are gradually eliminated; on the one hand, the glass-ceramic substrate is subjected to solid-phase diffusion reaction with the glass-ceramic substrate and permeates into the surface layer of the glass-ceramic substrate. With the gradual rise of the temperature, especially at 850 ℃, the solid-phase diffusion reaction speed between the silver powder as the main functional phase component and the glass phase is increased, and the porosity is gradually reduced to form a compact film layer. An ideal conductive layer can be obtained at a proper sintering temperature, and various performances such as conductivity, adhesive force, weldability, welding resistance and the like are superior. If the workpiece is over-burned, the glass phase in the conductor paste floats up, so that the weldability of the silver paste is reduced, namely the conductor paste is not easy to tin. If the workpiece is underburned, the densification of the conductor paste is incomplete, and the diffusion between various powder bodies in the conductor paste and the microcrystalline glass substrate is incomplete, so that the adhesion is insufficient, and the conductive layer is extremely easy to be eroded by tin.
Because the sintering of thick film slurry is an unbalanced sintering mainly of solid phase reaction, the sintering is different from the liquid phase sintering of metal smelting, and the heat and mass transfer of powder is carried out in a small range, so that the properties of functional phase powder such as silver powder have great influence on the film layer obtained after sintering. In general, the performance indexes of silver powder include morphology, particle size, tap density, specific surface area and the like. Silver powder generally has two main manufacturing methods: one is a liquid phase reduction method, namely, a reducing agent and a dispersing agent are added into a silver nitrate aqueous solution, silver ions crystallize, nucleate and grow up in the aqueous solution, silver powder with different performances is obtained by controlling factors such as reaction temperature, stirring speed and the like, and the method is a chemical synthesis method; the other is gas atomization, that is, a physical production method, in which a liquid molten silver fluid is broken into small droplets by high-speed air flow and solidified into powder, and the sphericity and purity of the liquid molten silver fluid are high. The silver powder produced by the liquid phase reduction method is generally adopted in the thick film paste, because the cost performance is higher, and particularly, the surface of the silver powder is coated with a layer of organic matters, and fluid with better rheological property and suitable for printing is formed more easily with the organic carrier in the thick film paste. And silver powder produced by the gas atomization method is used for thick film paste, and more parts are used for 3D printing and other occasions due to particle size distribution. How to select proper silver powder according to different application conditions is often a core technology for developing conductor paste or resistor paste.
The invention has the following beneficial effects:
1. the invention provides high-temperature conductive silver paste for a glass ceramic thick film heating plate, which comprises the following components in percentage by mass: 75-85%; composite glass powder: 1 to 5 percent; organic carrier: 10-24%. The silver powder has a spherical or nearly spherical shape, an average particle diameter of 1.5-3 microns and a tap density of 4.5About 6.5g/ml, and the specific surface area is 0.4-0.7 m 2 And/g. The composite glass powder comprises a component A and a component B in a mass ratio of 1-3:1, wherein the component B is silica micropowder, and the component A comprises, by mass, 35-50% of silicon oxide, 20-30% of boric acid, 10-15% of magnesium oxide, 5-10% of aluminum oxide, 3-5% of titanium oxide and 1-2% of zirconium oxide. The thermal expansion coefficient of the composite glass powder is 2.8-10 -6 The softening point is 755-762 ℃, the D50 is 0.8-1.3 microns, and the D99 is less than 10 microns. The main component of the silicon micropowder is silicon dioxide, the purity is 99.9 percent, and the average grain diameter is about 0.5 to 1 micron; the maximum particle size is not more than 2 microns.
The silver powder is used as a functional phase in the high-temperature silver paste of the glass ceramic thick film heating plate, and mainly plays roles of conducting and welding. The higher the silver powder content, the better the conductivity after sintering into a thick film conductor layer, the thicker the silver film layer formed, and the better the solderability and solder resistance of the conductor layer. Silver powder with large particle size, high tap density and low specific surface area is adopted, so that the shrinkage rate is small in the high-temperature sintering process, and cracks or bubbles are not easy to form. The composite glass powder is used as the bonding phase of thick film conductive silver paste, on one hand, the composite glass powder and the microcrystalline glass substrate form a bonding layer through solid phase diffusion, and on the other hand, the functional phase silver powder particles are bonded together. The silicon micropowder in the composite glass powder plays a role of pinning the glass phase in the high-temperature sintering process, so that on one hand, the shrinkage of the glass phase is reduced, and on the other hand, the thermal stress formed in the sintering process is regulated. The higher the glass phase content, the stronger the adhesion between the conductor sintering film and the glass ceramic substrate becomes, but the weldability gradually becomes worse, and the welding adhesion becomes smaller. The proportion of the glass phase is too small, and the solderability of the conductor paste is very good, but the adhesion with the glass-ceramic plate becomes poor, and the solder resistance is relatively poor. The content of the glass phase is within a reasonable range, and can give consideration to various performance indexes such as conductivity, substrate adhesion, weldability, welding resistance, welding adhesion and the like. The organic vehicle mainly affects the printing characteristics of the conductor paste. The higher the organic carrier content, the lower the general viscosity, with the same other influencing factors. The viscosity is too high, the conductive paste is not beneficial to penetrating through a silk screen, and the surface of the conductive layer is rough, so that the appearance is affected; the viscosity is too low and the printed out is easily feathered. The viscosity of the conductor paste is controlled within a reasonable range, which is favorable for improving the printing characteristic of the conductor paste, thereby obtaining a smooth and compact conductive sintering film.
2. The high-temperature conductive silver paste of the glass ceramic thick film heating plate is applied to glass ceramic, adopts a 850 ℃ high-temperature sintering process, has a heat preservation time of 5 to 10 minutes, does not lose efficacy after a plurality of sintering cycles, has excellent performance under current impact resistance, can reach more than 1 ten thousand times, and has a power attenuation of less than 5 percent after 1000-hour life test. The conductive silver paste has strong adhesive force, the adhesive force is more than 40N (2 mm x 2mm test block), the weldability is more than 95%, the welding resistance is more than 3 times, the highest working temperature can reach more than 450 ℃, and the performance is excellent.
3. The high-temperature conductive silver paste of the glass ceramic thick film heating plate is well matched with a glass ceramic substrate, the conductor paste is not scraped by a paper cutter, the strength and the hardness are high, and the glass ceramic thick film heating plate has no bubbles and no cracking phenomenon. In addition, the weldability, the welding resistance and the adhesive force of the conductive silver paste are not reduced under the condition of multiple sintering at 850 ℃, and the application requirements of multiple sintering cycles of the microcrystalline glass plate can be met.
In addition to the objects, features and advantages described above, the present invention has other objects, features and advantages.
Detailed Description
The following detailed description of embodiments of the invention is provided, but the invention may be embodied in many different forms, which are defined and covered by the claims.
Example 1
The high-temperature conductive silver paste for the glass ceramic heating plate comprises, by mass, spherical silver powder (tap density of 6.5g/ml, average particle size of 1.8 μm, and specific surface area of 0.4 m) 2 /g): 82%; composite glass powder: 3%; organic carrier: 15%.
Wherein the thermal expansion coefficient of the composite glass powder is 2.8 x 10 -6 At a temperature of between 755 and 762 ℃, the softening point comprises a component A and a component B in a mass ratio of 1:1, wherein the component A is a polyurethane resinThe component B is silica micropowder, and the component A comprises, by mass, 35-50% of silicon oxide, 20-30% of boric acid, 10-15% of magnesium oxide, 5-10% of aluminum oxide, 3-5% of titanium oxide and 1-2% of zirconium oxide.
The organic carrier comprises the following components in percentage by mass: 30-40% of alcohol ester, 10-20% of tributyl citrate, 10-20% of dibasic ester, 5-10% of butyl carbitol acetate, 5-10% of ethylene glycol phenyl ether and 1003-6% of ethyl cellulose Dow chemical STD; the components are decocted in water bath at 80 ℃ for 4-6 hours to form uniform transparent solvent, and the transparent solvent is filtered by a 300-mesh polyester net to prepare the product.
The preparation method comprises the following steps:
1) Uniformly mixing the component A in the composite glass powder by using a mixer, smelting in a high-temperature smelting furnace by using a platinum crucible, preserving heat for 15 minutes at 300 ℃, heating to 900 ℃, preserving heat for 15 minutes, heating to 1550 ℃, preserving heat for 1 hour, and quenching by water;
2) And mixing the component A and the component B in proportion, performing ball milling to obtain the glass ceramic composite glass powder with low thermal expansion coefficient and high softening point, and measuring the composite glass powder.
3) Uniformly mixing the composite glass powder, silver powder and an organic carrier in a centrifugal deaerating machine at the speed of 1200 revolutions per minute, and rolling for 5-6 times by a three-roller mill to obtain the high-temperature conductive silver paste of the glass ceramic thick film heating plate.
The conductive paste prepared in this example has a viscosity of 165 Pa.S and a fineness of less than 10 μm.
Example 2:
the high-temperature conductive silver paste for the glass ceramics heating plate comprises, by mass, microcrystalline silver powder (tap density 4.5g/ml, average particle size 2.1 μm, specific surface area 0.42 m) 2 /g): 82%; composite glass powder: 3%; organic carrier: 15%;
the thermal expansion coefficient of the composite glass powder is 2.8-10 -6 The softening point is 755-762 ℃, the composition comprises a component A and a component B in a mass ratio of 1:1, wherein the component B is silica micropowder, and the component A comprises 35-50% of silicon oxide, 20-30% of boric acid and oxidation in percentage by mass10-15% of magnesium, 5-10% of alumina, 3-5% of titanium oxide and 1-2% of zirconium oxide.
The organic carrier comprises the following components in percentage by mass: 30-40% of alcohol ester, 10-20% of tributyl citrate, 10-20% of dibasic ester, 5-10% of butyl carbitol acetate, 5-10% of ethylene glycol phenyl ether and 1003-6% of ethyl cellulose Dow chemical STD; the components are decocted in water bath at 80 ℃ for 4-6 hours to form uniform transparent solvent, and the transparent solvent is filtered by a 300-mesh polyester net to prepare the product.
The specific preparation method is the same as in example 1, and the viscosity of the prepared conductive paste is 168 Pa.S, and the fineness is less than 10 microns.
Example 3:
the high-temperature conductive silver paste for the glass ceramics heating plate comprises, by mass, microcrystalline silver powder (tap density 4.5g/ml, average particle size 2.1 μm, specific surface area 0.42 m) 2 /g): 75%; composite glass powder: 3%; organic carrier: 22%.
The thermal expansion coefficient of the composite glass powder is 2.8-10 -6 The softening point is 755-762 ℃ and comprises a component A and a component B in a mass ratio of 3:1, and the component A and the component B in the specifically adopted composite glass powder and the organic carrier are the same as those in the example 1. The conductive paste prepared in this example had a viscosity of 175 Pa.S and a fineness of less than 10. Mu.m.
Example 4:
the high-temperature conductive silver paste for the glass ceramics heating plate comprises, by mass, glass ceramics silver powder (tap density is 6.5g/ml, average particle size is 1.8 μm, specific surface area is 0.4 m) 2 /g): 85%; composite glass powder: 1%; organic carrier: 14%.
The thermal expansion coefficient of the composite glass powder is 2.8-10 -6 The softening point is 755-762 ℃ and comprises a component A and a component B in a mass ratio of 2:1, and the component A and the component B and the organic carrier in the specifically adopted composite glass powder are the same as those in the example 1. The conductive paste prepared in this example has a viscosity of 180 Pa.S and a fineness of less than 10 μm.
Comparative example 1: (use of microcrystalline silver powder)
Microcrystalline glassThe high-temperature conductive silver paste of the glass heating plate comprises microcrystalline silver powder (tap density is 2.78g/m, average grain diameter is 0.8 micrometer, specific surface area is 3.17m 2 /g): 82%; composite glass powder: 3%; organic carrier: 15%;
comparative example 1 the same as in example 1 was conducted except that silver powder was used.
The specific preparation method is the same as in example 1, and the viscosity of the prepared conductive paste is 185 Pa.S, and the fineness is less than 10 microns.
Comparative example 2: (high temperature Ca-Al-Si glass powder is adopted)
The high-temperature conductive silver paste for the glass ceramic heating plate comprises, by mass, spherical silver powder (tap density of 6.5g/ml, average particle size of 1.8 μm, and specific surface area of 0.4 m) 2 /g): 82%; glass powder: 3%; organic carrier: 15%;
the glass powder is high-temperature calcium aluminum silicon glass powder, and the thermal expansion coefficient is 7.8 x 10 -6 The softening point is 750-760 ℃, and the softening agent comprises the following components in percentage by mass: 32% of calcium oxide; 25% of alumina; 20% of silicon oxide, 15% of boric acid and 3% of barium oxide; 3% of titanium oxide; zirconia 1%; 1% of strontium oxide.
Comparative example 2 the procedure of example 1 was followed except that the glass frit was used.
The specific preparation method is the same as in example 1, and the viscosity of the prepared conductive paste is 169 Pa.S, and the fineness is less than 10 microns.
Comparative example 3: (microcrystalline silver powder is adopted, and high-temperature calcium aluminum silicon glass powder is adopted)
The high-temperature conductive silver paste for the glass ceramics heating plate comprises, by mass, glass ceramics silver powder (tap density of 2.78g/m, average particle size of 0.8 μm, specific surface area of 3.17 m) 2 /g): 82%; glass powder: 3%; organic carrier: 15%;
the glass powder is high-temperature calcium aluminum silicon glass powder, and the thermal expansion coefficient is 7.8 x 10 -6 The softening point is 750-760 ℃, and the softening agent comprises the following components in percentage by mass: 32% of calcium oxide; 25% of alumina; 20% of silicon oxide, 15% of boric acid and 3% of barium oxide; 3% of titanium oxide; zirconia 1%; 1% of strontium oxide.
Comparative example 3 is different from comparative example 2 in that the silver powder used is different and the others are the same.
The specific preparation method is the same as in example 1, and the viscosity of the prepared conductive paste is 175 Pa.S, and the fineness is less than 10 microns.
Comparative example 4 (composite glass frit with A component only and no silica fume added)
The high-temperature conductive silver paste for the glass ceramic heating plate comprises, by mass, spherical silver powder (tap density of 6.5g/ml, average particle size of 1.8 μm, and specific surface area of 0.4 m) 2 /g), 82%; the component A in the composite glass powder comprises: 3%; organic carrier: 15%.
Comparative example 4 differs from example 1 in that: the composite glass powder has the same dosage, but only contains the component A, and no silica micropowder is added; otherwise, the same as in example 1 was conducted.
Other preparation methods are the same as in example 1, and the viscosity of the conductive paste prepared in this example is 160 Pa.S, and the fineness is less than 10 μm.
The conductive silver pastes prepared in examples 1-2 and comparative examples 1-4 were formed into conductive layers using the same sintering process, specifically: printing the prepared conductive paste on the surface of a microcrystalline glass heating substrate by using a 200-250-mesh stainless steel composite screen, sequentially drying at 150 ℃ for 8-15 minutes, and finally sintering for 5-10 minutes at the peak sintering temperature of 850 ℃ under a mesh belt sintering furnace through which dry air is introduced. And then respectively observing the surface, testing the weldability, the welding resistance, the adhesive force and the current impact resistance. Considering that the conductor paste is often required to be sintered for many times in practical application, a re-sintering test is added, namely, a first test sample wafer is put into a mesh belt furnace again to be sintered for one time at 850 ℃, the appearance is observed, and whether the weldability, the welding resistance and the adhesive force are changed is tested.
Wherein, the surface state observation is observed under a 200-time optical microscope;
weldability test: dipping the solder with SnAgCu in a constant temperature tin furnace at a temperature of 260 ℃ at 90 DEG for 10 seconds perpendicular to a tin surface, and measuring the tin loading area ratio;
and (3) welding resistance test: adopting SnAgCu solder, keeping the temperature of a tin furnace, immersing the solder in a state of being perpendicular to a tin surface for 10 seconds at a temperature of 260 ℃, and completely calculating a bonding pad once;
adhesion test: adopting a 2mm x 2mm welding pad, bending an L-shaped tinned copper wire with the diameter of 0.8mm, and welding at the constant temperature of 400 ℃;
current impact resistance test: under the same power condition of 1000W, the pulse of 30 seconds of continuous energization and 30 seconds of cooling is used for impacting 1000 times, and the change rate of the electrical resistance value is measured and calculated, wherein the calculation formula is DeltaR= (R end-R beginning)/R beginning) which is 100%.
The specific experimental results are shown in table 1:
table 1:
as can be seen from table 1: by comparison between example 1 and example 2, the silver powder was used as a silver powder, and the components were identical. The silver powder adopted in the example 1 has higher tap density, smaller specific surface area, better adhesive force and stronger current impact resistance. This is because silver powder having a higher tap density is more dense in the silver layer obtained after sintering, and has a better binding force with the substrate and a stronger current impact resistance. The silver powder in example 2, although having a lower tap density than that in example 1, has a smaller specific surface area due to a larger particle size, and has a smaller shrinkage during sintering, and is also substantially satisfactory for product applications.
By comparing example 1, example 2 and comparative example 1, the glass powders of the three are the same, and the proportions of the organic carriers are similar. The microcrystalline silver powder with small particle size, high specific surface area and low tap density is selected in the comparative example 1, and the shrinkage proportion of the silver powder is larger, the surface roughness is larger, the density of the sintered film layer is obviously inferior to that of the examples 1 and 2, and although the surface is not obviously defective, the weldability, the welding resistance and the adhesive force are poorer, and the current resistance is weakened. Especially in the re-firing test of the simulation product with multiple sintering cycles, the edge of the conductor layer can be partially fallen off, which can lead to cracking at the joint with the resistance paste in practical application and open circuit. Therefore, the silver powder with large particle size, small specific surface and high tap density is more suitable for application in microcrystalline glass conductor slurry due to the fact that the silver powder has smaller sintering shrinkage ratio.
By comparing example 1 with comparative example 2, both of which use silver powder identical to the organic vehicle, example 1 used a thermal expansion coefficient of 2.8X10 -6 Low CTE glass frit at temperature/DEG C, comparative example 2 used a CTE of 7.8X10 -6 High coefficient of thermal expansion glass frit at/deg.c. Since the thermal expansion coefficient of the glass-ceramic substrate is close to zero, the thermal expansion mismatch between the glass powder with a high thermal expansion coefficient and the glass powder with a low thermal expansion coefficient is more serious than that of the glass-ceramic substrate, and the difference is not particularly obvious from the appearance, but the thermal stress actually exists is larger. In the re-firing process, the edge of the conductor layer of comparative example 2 was locally peeled off, because the thermal expansion mismatch between the conductor layer and the glass-ceramic substrate was further deteriorated by the further high-temperature sintering. And as the number of sintering increases, the peeling of the conductor layer is further increased. It can be seen that a glass with a low coefficient of thermal expansion is more suitable for the glass phase of the conductor paste for glass-ceramic plates.
By comparing comparative example 2 with comparative example 3, both of which use glass frit having a high thermal expansion coefficient, comparative example 2 uses silver powder having a large particle size, a low specific surface area, and a high tap, and comparative example 3 uses silver powder having a small particle size, a large specific surface area, and a low tap. The conductor paste of comparative example 3 was relatively inferior in surface quality, and thermal expansion mismatch was more prominent, and performance was relatively inferior, due to the relatively larger shrinkage ratio of silver powder during high temperature sintering. Whereas for conventional ceramic substrates, comparative example 3 was completed to meet the application requirements. The reason why the application requirements cannot be met on the microcrystalline board is that various defects such as cracking and foaming are generated due to the large difference of the thermal expansion coefficients, and densification in the sintering process cannot be realized.
By comparing comparative example 4 with example 1, the difference is that only the a component in the composite glass frit is used in comparative example 4, and no fine silica powder is added. Otherwise, the same applies. From the test results, the conductor paste in comparative example 4 was hardly different from example 1 in appearance, weldability, solder resistance, adhesion. The difference is that the rate of change of the resistance value in comparative example 4 was 7.5% in terms of current surge resistance, and was 1.6% larger than that in example 1. In addition, during the re-firing process, the solderability and adhesion of the conductor layer in comparative example 4 were somewhat reduced. The reason is most likely that the glass powder was floated during sintering because the high melting point fine silica powder was not added in comparative example 4 during re-sintering, thereby forming a very thin glass layer on the surface of the conductor paste, and tin was not easily penetrated through the glass layer and silver to form a silver-tin alloy during welding, thereby causing a decrease in weldability and also affecting the welding adhesion. On the one hand, the composite glass powder in the embodiment 1 improves the softening point of the composite glass powder due to the silicon micro powder with high melting point, and the conductor paste has stronger high-temperature sintering resistance in the process of re-sintering; on the other hand, the silicon micropowder is dispersed in the glass bonding phase in the high-temperature sintering process, so that the viscosity of the glass bonding phase is reduced in the softening process, the solid-phase diffusion reaction speed of the glass bonding phase and the glass substrate is reduced, and the silicon micropowder is prevented from being diffused deeper to generate larger thermal stress, thereby improving the current impact resistance and the re-firing resistance. In the course of manufacturing a glass ceramic thick film heating element, the conductor paste undergoes multiple sintering, which is a necessary property in the process, and it is seen that example 1 is more suitable for use than comparative example 4. The results of example 3 and example 4 are similar to those of example 1 and will not be described in detail here.
In conclusion, the high-temperature conductive silver paste of the microcrystalline glass thick film heating plate, which has high weldability, strong adhesive force, high resistance to heavy current impact, high stability in re-firing and excellent overall performance, is obtained through the mutual synergistic effect of the specific components and the corresponding proportions, wherein the highest working temperature can reach more than 450 ℃. The silver powder is used as a functional phase in the high-temperature silver paste of the glass ceramic thick film heating plate, and mainly plays roles of conducting and welding. The higher the silver powder content, the better the conductivity after sintering into a thick film conductor layer, the thicker the silver film layer formed, and the better the solderability and solder resistance of the conductor layer. Silver powder with large particle size, high tap density and low specific surface area is adopted, so that the shrinkage rate is small in the high-temperature sintering process, and cracks or bubbles are not easy to form. The composite glass powder is used as the bonding phase of thick film conductive silver paste, on one hand, the composite glass powder and the microcrystalline glass substrate form a bonding layer through solid phase diffusion, and on the other hand, the functional phase silver powder particles are bonded together. The silicon micropowder in the composite glass powder plays a role of pinning the glass phase in the high-temperature sintering process, so that on one hand, the shrinkage of the glass phase is reduced, and on the other hand, the thermal stress formed in the sintering process is regulated. The higher the glass phase content, the stronger the adhesion between the conductor sintering film and the glass ceramic substrate becomes, but the weldability gradually becomes worse, and the welding adhesion becomes smaller. The proportion of the glass phase is too small, and the solderability of the conductor paste is very good, but the adhesion with the glass-ceramic plate becomes poor, and the solder resistance is relatively poor. The content of the glass phase is within a reasonable range, and can give consideration to various performance indexes such as conductivity, substrate adhesion, weldability, welding resistance, welding adhesion and the like. The organic vehicle mainly affects the printing characteristics of the conductor paste. The higher the organic carrier content, the lower the general viscosity, with the same other influencing factors. The viscosity is too high, the conductive paste is not beneficial to penetrating through a silk screen, and the surface of the conductive layer is rough, so that the appearance is affected; the viscosity is too low and the printed out is easily feathered. The viscosity of the conductor paste is controlled within a reasonable range, which is favorable for improving the printing characteristic of the conductor paste, thereby obtaining a smooth and compact conductive sintering film.
The high-temperature conductive silver paste of the glass ceramic thick film heating plate is applied to glass ceramic, adopts a 850 ℃ high-temperature sintering process, has a heat preservation time of 5 to 10 minutes, does not lose efficacy after a plurality of sintering cycles, has excellent performance under current impact resistance, can reach more than 1 ten thousand times, and has a power attenuation of less than 5 percent after 1000-hour life test. The conductive silver paste has strong adhesive force, the adhesive force is more than 40N (2 mm x 2mm test block), the weldability is more than 95%, the welding resistance is more than 3 times, the highest working temperature can reach more than 450 ℃, and the performance is excellent. The high-temperature conductive silver paste is well matched with the microcrystalline glass substrate, the conductor paste cannot be scraped by a paper cutter, the strength and the hardness are high, and the high-temperature conductive silver paste has no bubbles and no cracking phenomenon. In addition, the weldability, the welding resistance and the adhesive force of the conductive silver paste are not reduced under the condition of multiple sintering at 850 ℃, and the application requirements of multiple sintering cycles of the microcrystalline glass plate can be met.
The above description is only of the preferred embodiments of the present invention and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (8)
1. The high-temperature conductive silver paste for the glass ceramic thick film heating plate is characterized by comprising the following components in percentage by mass
Silver powder: 75-85%; composite glass powder: 1 to 5 percent; organic carrier: 10-24%;
the composite glass powder comprises a component A and a component B in a mass ratio of 1-3:1;
the component B is silica micropowder, and the component A comprises, by mass, 35-50% of silicon oxide, 20-30% of boric acid, 10-15% of magnesium oxide, 5-10% of aluminum oxide, 3-5% of titanium oxide and 1-2% of zirconium oxide.
2. The high-temperature conductive silver paste for a glass ceramic thick film heating plate according to claim 1, wherein the silver powder is spherical, has an average particle diameter of 1.5-3 microns, a tap density of 4.5-6.5 g/ml and a specific surface area of 0.4-0.7 m 2 /g。
3. The high-temperature conductive silver paste for a glass ceramic thick film heating plate according to claim 1, wherein the silicon micropowder comprises silicon dioxide with a purity of 99.9% and an average particle size of 0.5-1 μm; the maximum particle size is not more than 2 microns.
4. The high temperature conductive silver paste for a glass ceramic thick film heating plate of claim 1, wherein said composite glass frit has a thermal expansion coefficient of 2.8 x 10 -6 The softening point is 755-762 ℃, the D50 is 0.8-1.3 microns, and the D99 is less than 10 microns.
5. The high-temperature conductive silver paste for a glass ceramic thick film heating plate according to claim 1, wherein the organic carrier comprises, in mass percent: 30-40% of alcohol ester, 10-20% of tributyl citrate, 10-20% of dibasic ester, 5-10% of butyl carbitol acetate, 5-10% of ethylene glycol phenyl ether and 1003-6% of ethyl cellulose Dow chemical STD; the components are decocted in water bath at 80 ℃ for 4-6 hours to form uniform transparent solvent, and the transparent solvent is filtered by a 300-mesh polyester net to prepare the product.
6. The high temperature conductive silver paste for a glass ceramic thick film heating plate according to any one of claims 1 to 5, wherein the viscosity of the conductive silver paste is 140 to 180 pa-sec, and the fineness is not more than 15 μm.
7. The method for preparing the high-temperature conductive silver paste for the glass ceramic thick film heating plate according to any one of claims 1 to 6, which is characterized by comprising the following steps:
1) Firstly, uniformly mixing the component A in the composite glass powder by using a mixer, smelting in a high-temperature smelting furnace, preserving heat at 300 ℃ for 15 minutes, heating to 900 ℃, preserving heat for 15 minutes, heating to 1550 ℃, preserving heat for 1 hour, and carrying out water quenching;
2) Mixing the component A and the component B in proportion, and performing ball milling to obtain composite glass powder with low thermal expansion coefficient and high softening point;
3) Uniformly mixing the composite glass powder, silver powder and an organic carrier in a centrifugal deaerating machine at the speed of 1200 revolutions per minute, and rolling for 5-6 times by a three-roller mill to obtain the high-temperature conductive silver paste of the glass ceramic thick film heating plate.
8. The sintering process of the high-temperature conductive silver paste of the glass ceramic thick film heating plate is characterized by comprising the following steps of: printing the high-temperature conductive silver paste of the glass ceramic thick film heating plate according to any one of claims 1-6 on the surface of a glass ceramic heating substrate by using a 200-250-mesh stainless steel composite screen, sequentially drying at 150 ℃ for 6-8 minutes, and finally sintering at the peak sintering temperature of 800-850 ℃ under a mesh belt sintering furnace through which dry air is introduced for 4-6 minutes, wherein the time from one end of the sintering furnace to the completion of sintering from the other end of a sample piece is 28-32 minutes, and forming a conductive layer on the surface of the glass ceramic heating plate.
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| CN202210808740.2A CN117198588A (en) | 2022-07-11 | 2022-07-11 | High-temperature conductive silver paste for microcrystalline glass thick film heating plate, and preparation method and sintering process thereof |
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| Publication Number | Publication Date |
|---|---|
| CN117198588A true CN117198588A (en) | 2023-12-08 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210808740.2A Pending CN117198588A (en) | 2022-07-11 | 2022-07-11 | High-temperature conductive silver paste for microcrystalline glass thick film heating plate, and preparation method and sintering process thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN117198588A (en) |
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