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CN-122011869-A - LTCC electrode diffusion inhibition coating, preparation method and application thereof

CN122011869ACN 122011869 ACN122011869 ACN 122011869ACN-122011869-A

Abstract

The application discloses a coating for inhibiting diffusion of an LTCC electrode, a preparation method and application thereof. The coating comprises a base mixture and a filler, wherein the base mixture comprises a solvent and an adhesive, the sintering temperature of the filler is higher than the softening temperature of glass powder, the glass powder is used for forming green ceramic chips in LTCC technology, and the contact angle of the filler corresponding to the wettability of the glass powder is smaller than 90 degrees, so that the filler has good wettability. The adhesive has better adhesion with raw ceramic chips and silver paste, and the filler with sintering temperature higher than the softening temperature of glass powder and good wettability with the glass powder is selected, so that when the LTCC is sintered, the softened glass powder firstly infiltrates the filler and forms an isolation layer with metal, and the isolation layer prevents the formation of metal (such as silver) ion migration channels, thereby inhibiting the diffusion of metal.

Inventors

  • YU HAICHAO
  • CAO WENKAI
  • SHENG TAO

Assignees

  • 强一半导体(苏州)股份有限公司

Dates

Publication Date
20260512
Application Date
20260311

Claims (14)

  1. 1. The coating for inhibiting the diffusion of the LTCC electrode is characterized by comprising a base mixture and a filler, wherein the base mixture comprises a solvent and a binder, the sintering temperature of the filler is higher than the softening temperature of glass frit, and the glass frit is used for forming green ceramic tiles in the LTCC technology; the contact angle of the filler corresponding to wettability relative to the glass powder is smaller than 90 degrees.
  2. 2. The LTCC electrode diffusion suppressing coating of claim 1, wherein the filler has a sintering temperature of not less than 900 ℃.
  3. 3. The LTCC electrode diffusion inhibiting coating of claim 1, wherein the filler comprises at least one of the following characteristics: a) The mass ratio of the filler to the base mixture is (0.1-10) 1; b) The filler comprises ceramic powder; c) The median particle size interval of the filler is 10 nm-2 mu m.
  4. 4. The LTCC electrode diffusion suppressing coating of claim 3, wherein in the case where the LTCC electrode diffusion suppressing coating comprises a ceramic powder, the ceramic powder comprises at least one of alumina, zirconia, magnesia, titania, zinc oxide, ceria, mullite, cordierite, and magnesia alumina spinel.
  5. 5. The LTCC electrode diffusion inhibiting coating of claim 1, wherein the solvent comprises at least one of the following characteristics: a) The mass ratio of the solvent to the adhesive is (0.5-10): 1; b) The solvent includes at least one of an ester solvent, a ketone solvent, an aromatic hydrocarbon solvent, an alcohol solvent and an aliphatic hydrocarbon solvent.
  6. 6. The LTCC electrode diffusion suppressing coating of claim 4, wherein the ester solvent comprises butyl acetate, propyl ester, or ethyl ester; The ketone solvent comprises acetone, butanone or cyclohexanone; The aromatic hydrocarbon comprises toluene or xylene; The alcohol comprises methanol, ethanol, propanol or butanol; the aliphatic hydrocarbon comprises hexane, heptane or cyclohexane.
  7. 7. The LTCC electrode diffusion inhibiting coating of claim 1, wherein the binder comprises at least one of polyacrylate, polyurethane, silicone, polyester, polyvinyl butyral, and cellulose and derivatives thereof.
  8. 8. The LTCC electrode diffusion suppressing coating according to claim 6, wherein in the case where the binder comprises polyvinyl butyral or ethyl cellulose, the number average molecular weight of the polyvinyl butyral and the ethyl cellulose is 15000-40000 g/mol.
  9. 9. The LTCC electrode diffusion suppressing coating according to claim 1, wherein the base mixture comprises a dispersant, the dispersant being (0.01-0.3): 1; And/or the dispersant comprises at least one of castor oil, hydrogenated castor oil, polyacrylate, phosphate, fatty acid polyoxyethylene ether, sorbitan fatty acid ester and vinyl pyrrolidone polymer.
  10. 10. The LTCC electrode diffusion suppression coating according to claim 1, wherein the base mixture comprises a co-binder, the co-binder being (0.01-0.2) 1; and/or the auxiliary adhesive comprises at least one of an amino silane coupling agent, an epoxy silane coupling agent, a methacryloxy silane coupling agent, a vinyl silane coupling agent, a mercapto silane coupling agent and a titanate coupling agent.
  11. 11. The LTCC electrode diffusion suppressing coating according to claim 1, wherein the base mixture comprises a plasticizer, the plasticizer being (0.01-0.3) 1; And/or the plasticizer is at least one of dibutyl phthalate, dioctyl phthalate, diisodecyl phthalate, trioctyl trimellitate, tributyl citrate and butyryl-trihexyl citrate.
  12. 12. A method of preparing a LTCC electrode diffusion-inhibiting coating as claimed in any one of claims 1 to 10, said method comprising the steps of: The base mixture is stirred at 60-90 ℃ and 100-300 rpm ℃ for 2-4 h; ball milling the filler and the basic mixture under the condition of 100-300 rpm ℃ for 4-8 h to form filler mixed resin; And grinding the filler mixed resin, and obtaining the LTCC electrode diffusion inhibition coating after the grinding fineness is smaller than 8 mu m.
  13. 13. Use of a LTCC electrode diffusion inhibiting coating as claimed in any one of claims 1 to 11, comprising the steps of: Printing the coating on the green ceramic tile; Baking to remove the solvent; printing a metal slurry on a coating formed by the paint; Sintering the green ceramic tile with the coating and the metal slurry.
  14. 14. The use of LTCC electrode diffusion suppressing coating according to claim 13, characterized in that said use comprises at least one of the following features: a) Printing the coating on the green ceramic tile by using a silk screen with the thickness of 5-100 mu m; b) Baking at 60-120deg.C for 5-30 min to remove solvent in the coating; c) Printing a metal slurry on the coating using a 5-100 μm thick screen of the same pattern; d) The green ceramic tile with the coating and the metal slurry is sintered at a temperature of 700-950 ℃.

Description

LTCC electrode diffusion inhibition coating, preparation method and application thereof Technical Field The application belongs to the technical field of sintering, and particularly relates to a coating for inhibiting diffusion of an LTCC electrode, a preparation method and application thereof. Background LTCC (low temperature cofired ceramic) is a technique of one-time cofiring a multilayer unsintered ceramic green sheet with a metallic conductive paste (typically silver, silver palladium alloy or copper) at a relatively low temperature (typically 800 ℃ to 900 ℃). This process feature makes LTCCs incomparable machinability, and ceramic green sheets can be fabricated by precision punching, hole filling, printing, etc. to build complex vertical interconnect channels and passive devices (e.g., resistors, capacitors, inductors, filters, antennas, etc.) in three dimensions before sintering. This not only saves space significantly, reduces the path and loss of signal transfer between components, but also significantly improves the mechanical strength and interconnect reliability of the system. LTCCs have a low dielectric constant and very low dielectric loss that are tunable, which allows the signal to remain high-speed and low-attenuation during transmission, particularly in the Radio Frequency (RF) and microwave, millimeter wave bands. In addition, the high thermal conductivity of the ceramic material and the thermal expansion coefficient similar to that of the silicon chip enable the ceramic material to effectively dissipate heat in a high-power working environment, and reduce welding spot failure caused by thermal stress. These characteristics make LTCC the preferred solution in the field where frequency and reliability are critical, such as 5G/6G communications, satellite communications, car-mounted radar, high-end test instruments, etc. However, under conditions of high temperature, high humidity, electric field, long-term service, or the like, silver (Ag) ions or atoms have a phenomenon of migration from the conductor line to the surrounding ceramic dielectric layer, i.e., silver diffusion. This is due to the fact that glass phases (e.g., borosilicate glass) are typically added to LTCC ceramics to lower the melting point, and these glass phases soften during sintering and subsequent high temperatures, as a rapid pathway for silver ion migration. During sintering, silver may excessively penetrate into the ceramic, resulting in fine conductor linewidth deformation, edge blurring, and direct impact on performance accuracy of the high frequency circuit. Silver ion migration is exacerbated especially in high temperature and high humidity environments (e.g., severe test conditions at 85 ℃ per 85% rh), coupled with actuation of the electric field. The damage is mainly characterized in that firstly, electromigration in a conductor causes local thinning and even fracture of a conductor wire to cause open circuit of a circuit, secondly, silver ions migrate along the surface or the inside of a medium between two adjacent conductors with different potentials to form conductive dendrites, and finally, insulation resistance is reduced, leakage current is increased, and even short circuit failure occurs. For very high integration, very small line spacing LTCCs, such failure is catastrophic and difficult to predict. Disclosure of Invention The application aims to overcome the defects in the prior art and provides a coating for inhibiting diffusion of LTCC electrodes, a preparation method and application thereof, wherein the coating can inhibit migration of metal (such as silver) from a conductor line to a surrounding ceramic dielectric layer. In order to achieve the aim, the technical scheme adopted by the application is that the LTCC electrode diffusion inhibition coating comprises a base mixture and a filler, wherein the base mixture comprises a solvent and an adhesive, the sintering temperature of the filler is higher than the softening temperature of glass powder, the glass powder is used for forming green ceramic chips in the LTCC technology, and the contact angle of the filler corresponding to wettability of the filler relative to the glass powder is smaller than 90 degrees. In some embodiments, the sintering temperature of the filler is not less than 900 ℃. In some embodiments, the filler comprises at least one of the following features: a) The mass ratio of the filler to the base mixture is (0.1-10) 1; b) The filler comprises ceramic powder; c) The median particle size interval of the filler is 10 nm-2 mu m. In some embodiments, where the LTCC electrode diffusion inhibiting coating comprises a ceramic powder, the ceramic powder comprises at least one of alumina, zirconia, magnesia, titania, zinc oxide, ceria, mullite, cordierite, and magnesia alumina spinel. In some embodiments, the solvent includes at least one of the following features: a) The mass ratio of the solvent to the adhesive is (0.5-10): 1; b) The sol