A kind of formula and processing technology of modified stannic oxide electrode paste for ceramic capacitor
Technical field
A kind of modified stannic oxide electrode paste for ceramic capacitor of the present invention relates to the electrode slurry of ceramic capacitor.
Background technology
Ceramic capacitor, through development for many years, has formed stable technical system now.Take pottery as medium, smear silver electrode and welding lead with screen printing mode on ceramic dielectric two sides, and use the ceramic condenser that epoxy resin is insulating protective layer.At present, components and parts are widely used in the various electronic applications such as television set, DVD, sound equipment, air-conditioning, computer, electronic instrument, electronic toy, along with popularizing of household electrical appliance, the demand of ceramic condenser increases year by year, and then also progressively increase as the conductive silver paste demand of capacitance electrode, to 2008, only the use amount of China's conductive silver paste was just more than 1500 tons.Argent is as the main material of conductive silver paste, and the content in silver slurry is more than 50%.Along with the increase of conductive silver paste use amount, the demand of China to argent also increases fast.But started international raw material to 2006 to go up fast, the price of noble metal rapidly goes up especially.In 2006 1 year, international silver-colored valency rising range is more than 200%.In the end of the year 2008, world financial crisis occurs, and dollar gives up soft, causes gold, silver becomes hard logical deposit, the investment way of value preserving.International silver-colored price especially every day a new peak.Current silver-colored valency is up to 3960 yuan/KG, and make super fine silver powder and also want 250 yuan of processing charges, namely silver powder price is 4210 yuan/KG; If dollar continues to devalue, then silver is worth and also can raises.Silver valency go up, as ceramic capacitor prime cost form the corresponding rise of conductive silver paste price, and every day several price, greatly improve the manufacturing cost of ceramic capacitor.Also development and the popularization of each components and parts producer is constrained.Therefore, the subject matter becoming each components and parts manufacturer and face at present how is reduced costs.
Secondly silver electrode also has a lot of shortcoming:
1, silver electrode high-temperature-resistant soldering tin is poor, and when carrying out scolding tin process, silver electrode is easily corroded by solder, and we cry " eating silver " and make silver electrode lower thickness or occur sawtooth.The electrode designing size like this there will be problem, and capacitance can reduce and withstand voltagely occurs that point discharge is bad.Even if some producers add the silver of 2%-3.5% in the tin of solder, and the copper of 0.5-0.1%, but cost can rise again, has a strong impact on the market competitiveness.
2, silver ink firing temperature is high, and the sintering temperature of traditional silver electrode is between 800 DEG C-820 DEG C, and because temperature is high, power consumption is just large, and silver ink firing workman does not note taking precautions against, and the silver-colored chip of print can be caused secretly to split, and electric property declines.
3, silver electrode is on the circuit of long-term work, can produce position " silver migration " phenomenon, cause electric field to change, and produce bad.Therefore be necessary to research and develop new product, to solve above-mentioned shortcoming and problem.
Current portions slurry industry and enterprise and research institution adopt new material to come alternative silver powder conducting function phase aspect and sound out, and they mainly concentrate on the substitution studies with metal-powders such as nickel, copper, silver-colored copper-clad, silver-colored nickel coats, make slow progress.Tracing it to its cause is that 1. base metal antioxygenic property is poor, just starts oxidation at 300 DEG C of temperature.2. the coefficient of expansion of base metal, grainiess, intermolecular stress is equipped with pottery and has problems.
Summary of the invention the present invention is directed to above-mentioned traditional processing technology in raw material use Problems existing and deficiency, after the research to materials such as copper powder, nickel powder, graphite, carbon black, glass puttys, propose a kind of new material and carry out alternative silver powder conducting function phase---a kind of formula of modified stannic oxide electrode paste for ceramic capacitor, the technical program has following characteristics:
A kind of modified stannic oxide electrode paste for ceramic capacitor, by conducting function phase, bonding phase, levelling agent, coupling agent and solvent composition, each component ratio is as follows: conducting function is tin dioxide powder 60% ~ 70% mutually, tin dioxide powder be by antimony modification after tin dioxide powder; Bonding be mutually bismuth oxide, boron oxide, aluminium oxide, cupric oxide, lanthana, silver oxide composition lead-free low-temperature glass dust 1% ~ 5%, the each Ingredient Wt ratio of Binder Phase is: bismuth oxide 80 ~ 90%, boron oxide, aluminium oxide, cupric oxide, lanthana, silver oxide each 1.5 ~ 3%, brium carbonate 0.6 ~ 0.9%, titanium dioxide 0.01 ~ 0.05%; Levelling agent is polyvinyl acetate 1% ~ 5%; Coupling agent is the mixture 15% ~ 20% of ethyl cellulose and butyl carbitol, and the Ingredient Wt of coupling agent gets 8 ~ 15% than for ethyl cellulose, and butyl carbitol gets 85 ~ 92%.; Solvent is terpinol 15% ~ 20%.
A kind of modified stannic oxide electrode paste for ceramic capacitor production technology, comprises following flow process:
A. get 8 ~ 15% ethyl celluloses and 85 ~ 92% butyl carbitols to carry out stirring and form paste mixture, as coupling agent.
B. low-temperature lead-free glass dust is mixed with in proportion.The hybrid technique of low-temperature lead-free glass dust is: get bismuth oxide 80 ~ 95%, and boron oxide, aluminium oxide, cupric oxide, lanthana, silver oxide each 1 ~ 3%, is mixed into powders A; Get brium carbonate 80 ~ 95%, titanium dioxide 5 ~ 15% is mixed into powder B; Then A, B two kinds of powder according to 90 ~ 95%, 5 ~ 10% ratio again mix.
C. get conducting function phase 60%-70%, coupling agent 15-20%, bonding phase 1%--5%, levelling agent 1--5%, solvent 15--20%, mixing is put in high speed dispersor, high speed dispersion 1 hour.
D. and then put into three-high mill, 10--20 time is rolled.
E. cross 200 order nets, packaging, is 3070cu electrocondution slurry.
Product of the present invention has the advantage in following characteristics and market competition:
1. nonpoisonous and tasteless.Modification tin dioxide powder almost applies to environment and the occasion of any requirement conduction.
2. special Physicochemical is stablized.This powder in process of production, subjected to thermokalite, the test of the harsh conditions such as high temperature burning in hot acid and oxidizing atmosphere, acidproof, alkaline-resisting, organic solvent-resistant, fast light, and thermal stability is greater than 600 DEG C, is not oxidized, does not burn and have fire retardation.
3. conduct electricity very well, stable for extended periods of time.This powder resistance rate is less than 100 Ω .cm, and electrical property stable for extended periods of time puts 15 years in natural environment, and resistivity and other stable performance, do not affect by atmospheric humidity, temperature, oxic gas.
4. compatibility is good.Powder and various molecule base material, as epoxy, polyurethane, the resin such as acrylate, ABS, PVC, rubber etc. have good compatibility.
5. scattered.There is good dispersiveness in a solvent, at resin, in solvent, only need simple agitation namely to dispersible.
6. with low cost.Modification tin dioxide powder price is RMB 300 yuan/KG, compares, have absolute predominance with the super fine silver powder of 4000 yuan/KG.
7. energy-conserving and environment-protective.The product that the present invention produces---ceramic capacitor electrode modification tin ash slurry low 250-300 DEG C of its sintering temperature compared with traditional slurry, can save the energy in a large number, use lead-free cryogenic glass powder simultaneously, thus reach the effect of environmental protection and energy saving.
8. applied range.The product that the present invention produces---ceramic capacitor electrode modification tin ash slurry can extend be applied to other electron component as: varistor, thermistor, piezoelectric make ignition plug, potentiometer, piezoelectric ceramic transformer, ceramic GPS is wireless.
Embodiment
Get 12% ethyl cellulose and 88% butyl carbitol to carry out stirring and form paste mixture, as coupling agent.
Be mixed with low-temperature lead-free glass dust in proportion.The hybrid technique of low-temperature lead-free glass dust is: get bismuth oxide 82%, boron oxide, aluminium oxide, cupric oxide, lanthana, silver oxide each 1.5%; Get brium carbonate 0.48%, titanium dioxide 0.02% mixes.
Get conducting function phase 62%, coupling agent 15%, bonding phase 3%, levelling agent 3%, solvent 17%, mixing is put in high speed dispersor, high speed dispersion 1 hour.Then the mixture after dispersion is put into three-high mill, roll 10--20 time.Again by 200 order mesh screen choosings, then pack, be 3070cu electrocondution slurry.
(1) contrast test: conductive silver paste of the present invention and 8060HV silver are starched and contrasts
1, unified use 6020-y5p-k362 ceramic condenser element sheet
2, use 250 order is unified, 4.6+4.8 ¢, web plate size
3, conductive silver paste is 8060HV, and electroconductive tin dioxide slurry is 3070cu, and result is as follows:
(2) at the plain sheet of 8050-Y5P-K402, web plate 4.6+4.6 ¢; 250 order grenadines, by this ceramic chip capacitor of normal silk screen printing 3 editions, the electric capacity chip testing result under air after different temperatures sintering is as follows:
Two test datas more than we are comprehensive, can confirm that 3070cu electrocondution slurry can substitute conductive silver paste completely, all technical is all qualified.