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CN-122010554-A - Preparation method of ceramic powder material for base metal inner electrode X8R type MLCC

CN122010554ACN 122010554 ACN122010554 ACN 122010554ACN-122010554-A

Abstract

The invention discloses a preparation method of a ceramic powder material for an X8R type MLCC (metal-ceramic) of a base metal inner electrode. The ceramic powder takes barium titanate or partial substitutes thereof as basic dielectric components, and rare earth metal oxide, transition metal oxide and alkaline earth metal oxide are added in a synergistic way to serve as modifiers, and silicate sintering auxiliary agents are added. The preparation method comprises the steps of raw material pretreatment, mixing of ingredients and wet ball milling, granulation and molding, glue discharging and sintering at 1150-1250 ℃ in a reducing atmosphere. The ceramic powder can be well matched and co-fired with base metal electrodes such as nickel, copper and the like in H2-N2-H2O reducing atmosphere, the dielectric constant change rate of the obtained ceramic material is less than or equal to +/-15% in the temperature range of-55 ℃ to 150 ℃, the X8R specification is met, and meanwhile, the dielectric constant (1 kHz,25 ℃) is more than or equal to 1800, and the dielectric loss is less than or equal to 2%. The invention successfully solves the problems of compatibility of reduction sintering suitability and wide temperature stability of the base metal electrode MLCC.

Inventors

  • HE BIN
  • CHU TAO
  • HUANG BIXIANG
  • MU CHAO

Assignees

  • 中国振华(集团)新云电子元器件有限责任公司(国营第四三二六厂)

Dates

Publication Date
20260512
Application Date
20260120

Claims (9)

  1. 1. A preparation method of a ceramic powder material for an X8R type MLCC of a base metal inner electrode is characterized by comprising the following steps, Step 1, preparing and preprocessing raw materials, and drying basic dielectric ceramic powder, a modifier and a sintering aid, wherein the basic dielectric ceramic powder is barium titanate or barium titanate partially substituted by divalent metal ions, and the chemical formula of the basic dielectric ceramic powder is Ba 1 ₋ x A x TiO 3 , wherein A comprises but is not limited to Sr and Ca, and the value range of x is more than or equal to 0 and less than or equal to 0.05; Step 2, batching and mixing, namely weighing 90-97% of basic dielectric ceramic powder, 0-14% of modifier and sintering aid accounting for 0.05-3% of the total mass of the basic dielectric ceramic powder and the modifier according to the final composition of the ceramic powder, mixing the weighed raw materials with a dispersing agent and a solvent, and performing wet ball milling to obtain mixed slurry; Step 3, granulating and forming, namely drying and granulating the mixed slurry, pressing and forming to obtain a blank body, and performing glue discharging treatment on the blank body; step 4, sintering, namely placing the blank subjected to the glue discharging treatment in a reducing atmosphere, and sintering at the temperature of 1150-1250 ℃ to obtain a ceramic powder material; The dielectric constant change rate of the obtained ceramic powder material is less than or equal to +/-15% in the temperature range of-55 ℃ to 150 ℃, the dielectric constant at 1kHz and 25 ℃ is more than or equal to 1800, and the dielectric loss is less than or equal to 2%.
  2. 2. The method for producing ceramic powder material for base metal inner electrode X8R type MLCC according to claim 1, wherein said rare earth metal oxide comprises at least one of, but not limited to, Y 2 O 3 、Yb 2 O 3 、Dy 2 O 3 , said transition metal oxide comprises one or more of, but not limited to, mn 3 O 4 、ZrO 2 and NiO, and said alkaline earth metal oxide comprises one or more of, but not limited to, mgO, baO, caO.
  3. 3. The method for producing a ceramic powder material for a base metal inner electrode X8R-type MLCC according to claim 2, wherein the addition amount of the rare earth metal oxide is 5mol% or less, the addition amount of the transition metal oxide is 4 mol% or less, and the addition amount of the alkaline earth metal oxide is 5mol% or less based on the total molar amount of the ceramic powder.
  4. 4. The method for preparing ceramic powder material for base metal inner electrode X8R type MLCC according to claim 1, wherein the sintering aid is silicate including but not limited to SiO3 and BaCaSiO.
  5. 5. The method for preparing the ceramic powder material for the base metal inner electrode X8R type MLCC according to claim 1, wherein the dispersing agent in the step 2 comprises, but is not limited to, polyvinyl butyral, the solvent comprises, but is not limited to, ethanol, and the wet ball milling adopts yttria-stabilized zirconia balls as a ball milling medium.
  6. 6. The method for preparing the ceramic powder material for the base metal inner electrode X8R type MLCC according to claim 1, wherein the step 3 of drying and granulating the mixed slurry is specifically to spray-dry the mixed slurry to obtain dry powder. The dried powder was added to 7wt% PVA solution, and the mixture was sieved and granulated.
  7. 7. The method for preparing the ceramic powder material for the base metal inner electrode X8R type MLCC according to claim 1, wherein the discharging is characterized in that a tablet press is used for pressing the granulated powder into a blank with a required size, and the blank is placed in a heating furnace for discharging.
  8. 8. The method for preparing the ceramic powder material for the base metal inner electrode X8R type MLCC according to claim 1, wherein in the step 4, the reducing atmosphere is a mixed gas of H 2 、N 2 and water vapor, and the volume fraction of H 2 is 0.5% -3%.
  9. 9. The method for preparing the ceramic powder material for the base metal inner electrode X8R type MLCC according to claim 1, wherein the average particle size D50 of the prepared ceramic powder material is 0.2-0.4 mu m, the apparent density is 0.8-1.0 g/cm < 3 >, and the density of the ceramic body is more than or equal to 96% and the grain size is 0.2-2 mu m after sintering in a reducing atmosphere.

Description

Preparation method of ceramic powder material for base metal inner electrode X8R type MLCC Technical Field The invention relates to the technical field of dielectric ceramic materials for electronic components, in particular to a preparation method of a ceramic powder material for an X8R type MLCC (metal-ceramic) of a base metal inner electrode. Background Multilayer chip ceramic capacitors (MLCCs) are core passive components in electronic circuits, whose performance is highly dependent on the synergistic match between dielectric ceramic powder and electrode materials. Conventional MLCCs generally employ noble metals (e.g., pd-Ag alloys) as the inner electrode material. However, noble metal resources are scarce, the price fluctuation is large, the manufacturing cost of the MLCC is high, and the requirement of large-scale application in the fields of consumer electronics, automobile electronics and the like on cost control is difficult to meet. To reduce costs, industry is gradually moving towards the use of base metals (e.g., ni, cu) as internal electrodes. However, this transition presents two major challenges for dielectric ceramic powders, one of which is the problem of reductive sinter suitability. Base metal (Ni, cu) electrodes are susceptible to oxidation in an oxidizing atmosphere, and thus cofiring must be completed in a reducing atmosphere in which H 2-N2 is mixed. Whereas conventional barium titanate (BaTiO 3) -based porcelain powders are susceptible to a reduction reaction in a reducing atmosphere, resulting in deterioration of dielectric properties. Secondly, the X8R wide temperature characteristic requirement. The curie temperature of pure barium titanate is about 125 ℃, the dielectric constant of which is reduced by more than 30% at-55 ℃ and by more than 20% at 150 ℃, and the broad temperature stability required by the X8R specification cannot be satisfied. Therefore, the temperature characteristics of the porcelain powder must be widened and adjusted by effective element doping and modification. In the prior art, chinese patent publication No. CN114180952A discloses a doped bismuth ferrite-barium titanate-based leadless piezoelectric ceramic and a two-step sintering preparation method thereof. The ceramic material is prepared by specific chemical composition design and a two-step sintering process (firstly, heat preservation is carried out at 950-1050 ℃ for 1-2 minutes, then the temperature is reduced to 900-1000 ℃ and sintering is carried out for 6-10 hours), and the generation temperature range of a hetero-phase is avoided, so that the ceramic material with good crystallinity, uniform components, fine grains and excellent piezoelectric and dielectric properties is obtained. However, the technical scheme is mainly aimed at optimizing the performance of the piezoelectric ceramic, and the composition and the sintering process target (such as long-time heat preservation after high-temperature rapid sintering) of the piezoelectric ceramic are obviously different from those of dielectric ceramic powder which is applicable to base metal electrode MLCC and needs to be sintered into ceramic once in a reducing atmosphere and obtain specific temperature stability, so that the specific technical problems faced by the base metal electrode X8R type MLCC cannot be solved. In summary, developing a dielectric ceramic powder for MLCCs which has a high dielectric constant, satisfies the X8R wide temperature characteristic, can be subjected to reductive sintering at a lower temperature in combination with a base metal electrode, and is environment-friendly and low in cost becomes a key technical problem to be solved urgently in the current industry. Disclosure of Invention The invention aims to provide dielectric ceramic powder for a multilayer chip ceramic capacitor (MLCC) which is adaptive to base metal electrodes (nickel electrodes and copper electrodes) and meets the X8R temperature characteristic specification (-55-150 ℃) and the dielectric constant change rate is less than or equal to +/-15%), and an industrialized preparation method of the ceramic powder. The technical proposal of the invention is that the preparation method of the ceramic powder material for the base metal inner electrode X8R type MLCC comprises the following steps, Step 1, preparing and preprocessing raw materials, and drying basic dielectric ceramic powder, a modifier and a sintering aid, wherein the basic dielectric ceramic powder is barium titanate or barium titanate partially substituted by divalent metal ions, and the chemical formula of the basic dielectric ceramic powder is Ba 1₋xAxTiO3, wherein A comprises but is not limited to Sr and Ca, and the value range of x is more than or equal to 0 and less than or equal to 0.05; Step 2, proportioning and mixing, namely weighing 90-97% of basic dielectric ceramic powder, 0-14% of modifier, preferably, the modifier is not 0 and is specifically 3-10%, and sintering auxiliary agent accoun