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CN-122025218-A - Ultralow-temperature sintering silver paste for ultrasonic fingerprint module, and preparation method and application thereof

CN122025218ACN 122025218 ACN122025218 ACN 122025218ACN-122025218-A

Abstract

The invention discloses ultralow-temperature sintering silver paste for an ultrasonic fingerprint module, and a preparation method and application thereof, and belongs to the technical field of ultrasonic fingerprint module transmission media. The ultra-low temperature sintering silver paste for the ultrasonic fingerprint module comprises, by mass, 2% -5% of saturated polyester, 0.1% -1% of a curing agent, 0.01% -0.5% of a saturated polyester modification auxiliary agent, 80% -90% of nano silver powder, 2% -10% of a solvent, 0.1% -2% of a dispersing agent, 0.1% -0.5% of a silver paste sintering auxiliary agent, 0.1% -1.2% of a coupling agent and 0.1% -1% of a thixotropic agent, wherein the saturated polyester is a large molecular weight linear saturated polyester with a weight average molecular weight not less than 20000. The invention ensures that the sintering type silver paste has the advantages of low sintering temperature, high density, low touch, low surface roughness, no layering after lamination, no large-size holes and the like by optimizing the sintering type silver paste components.

Inventors

  • YIN WENGANG
  • Lei Weirui
  • LIU YUANZHE

Assignees

  • 北京中科纳通电子技术有限公司

Dates

Publication Date
20260512
Application Date
20260130

Claims (10)

  1. 1. The ultralow-temperature sintering silver paste for the ultrasonic fingerprint module is characterized by comprising, by mass, 2% -5% of saturated polyester, 0.1% -1% of a curing agent, 0.01% -0.5% of a saturated polyester modification auxiliary agent, 80% -90% of nano silver powder, 2% -10% of a solvent, 0.1% -2% of a dispersing agent, 0.1% -0.5% of a silver paste sintering auxiliary agent, 0.1% -1.2% of a coupling agent and 0.1% -1% of a thixotropic agent, wherein the saturated polyester is a large molecular weight linear saturated polyester with weight average molecular weight not lower than 20000.
  2. 2. The ultra-low temperature sintered silver paste for an ultrasonic fingerprint module according to claim 1, wherein the saturated polyester comprises at least one of aromatic saturated polyester, aliphatic saturated polyester and aromatic-aliphatic saturated polyester.
  3. 3. The ultra-low temperature sintered silver paste for an ultrasonic fingerprint module according to claim 1, wherein the curing agent comprises at least one of oxazoline, isocyanate, diisocyanate and dicyanate prepolymer.
  4. 4. The ultra-low temperature sintering type silver paste for an ultrasonic fingerprint module according to claim 1, wherein the saturated polyester modification auxiliary agent comprises at least one of acid anhydride, organic tin and acetylacetone metal salt.
  5. 5. The ultralow temperature sintering type silver paste for the ultrasonic fingerprint module according to claim 1 is characterized in that the nano silver powder comprises nano silver powder 1 with an average particle size of 50-150 nm and a silver content of 90% -95% in an irregular polygonal structure, nano silver powder 2 with an average particle size of 200-300 nm and a silver content of 90% -95% in an irregular polygonal structure, nano silver powder 3 with an average particle size of 200-400 nm and a silver content of 90% -95% in a sphere-like structure, and at least one of nano silver powder 4 with an average particle size of 200-400 nm and a silver content of 99% or more in a sphere-like structure.
  6. 6. The ultra-low temperature sintered silver paste for an ultrasonic fingerprint module according to claim 1, wherein the solvent comprises at least one of dibasic ester, dimethyl adipate, 3-methoxybutyl acetate, diethyl adipate, 3-methoxybutyl acetate and propylene glycol methyl ether acetate.
  7. 7. The ultra-low temperature sintered silver paste for an ultrasonic fingerprint module according to claim 1, wherein the dispersing agent comprises at least one of quaternary ammonium salt, polyvinylpyrrolidone, sodium oleate and TDO, and/or the silver paste sintering aid comprises at least one of sodium chloride, hydrazine hydrate, sodium borohydride and tris (2-aminoethyl) amine, and/or the coupling agent comprises at least one of silane coupling agent, titanate coupling agent, aluminate coupling agent, bimetallic coupling agent, phosphate coupling agent and borate coupling agent, and/or the thixotropic agent comprises at least one of fumed silica, organobentonite and polyamide wax.
  8. 8. A method for preparing ultralow temperature sintered silver paste for an ultrasonic fingerprint module according to any one of claims 1 to 7, comprising the following steps: Dissolving saturated polyester and a solvent at 90+/-5 ℃ to obtain a first mixture, adding a saturated polyester modification auxiliary agent, a silver paste sintering auxiliary agent, a coupling agent, a dispersing agent and a thixotropic agent into the first mixture, uniformly stirring, grinding to obtain a second mixture, adding nano silver powder and a curing agent into the second mixture, uniformly stirring, grinding, filtering and dispersing in vacuum to obtain the ultralow temperature sintering silver paste for the ultrasonic fingerprint module.
  9. 9. The method for preparing ultralow temperature sintered silver paste for an ultrasonic fingerprint module according to claim 8, wherein the filtration is 1500-3500 mesh high-mesh filtration, and/or the vacuum degree of vacuum dispersion is 1-5 kPa, the stirring speed is 200-1000 rpm, and the time is 10-30 min.
  10. 10. An application of the ultralow temperature sintered silver paste for the ultrasonic fingerprint module according to any one of claims 1-7 in preparing the ultrasonic fingerprint module.

Description

Ultralow-temperature sintering silver paste for ultrasonic fingerprint module, and preparation method and application thereof Technical Field The invention belongs to the technical field of ultrasonic fingerprint module transmission media, and particularly relates to ultralow-temperature sintering type silver paste for an ultrasonic fingerprint module as well as a preparation method and application thereof. Background The ultrasonic fingerprint module is a biological recognition technology ‌ for obtaining a 3D fingerprint image by transmitting ultrasonic waves to penetrate through the epidermis of a finger, has the characteristics of high safety, strong anti-interference performance and the like, and is widely applied to high-end smart phones and smart devices. The conductive silver paste used in the method has the advantages of sintering type silver paste and curing silver paste, compared with the sintering type silver paste, the curing silver paste has various limitations, such as (1) poor high temperature resistance, easy generation of thermal stress between a piezoelectric layer and a substrate, interface peeling or performance attenuation, (2) low temperature curing type silver paste, due to existence of resin and partial organic auxiliary agents, low compactness after curing of the silver paste due to low temperature problem in the baking process, partial solvent residues and air residues in the curing process, difficult elimination of pores which can form 0.5-2 microns, attenuation of ultrasonic signals, direct influence on final imaging definition and fingerprint unlocking accuracy, and (3) low temperature curing type ultrasonic fingerprint module silver paste, due to the existence of resin, inevitably causes separation of partial silver powder and resin, causes insulation of different degrees, and (4) mole pattern problem. Compared with the solidified silver paste, the sintered silver paste has better conductive performance, higher connection reliability, higher efficiency of thermal management, stronger environmental adaptability, better long-term stability and low risk of moire. When the ultra-low temperature sintering type silver paste is used for an ultrasonic fingerprint technology, the high conductivity and low dielectric loss (tan delta is less than 0.002) of the ultra-low temperature sintering type silver paste can optimize signal transmission between a sensor and a circuit, so that the unlocking success rate of a module is improved by more than 80% under the environments of wet hands, greasy dirt, strong light and the like, and meanwhile, the unlocking within 1 meter of water is supported. How to further improve the performance of ultralow temperature sintering type silver paste for an ultrasonic fingerprint module is one of the research directions of the ultrasonic fingerprint module. Disclosure of Invention The invention aims to provide ultralow-temperature sintering silver paste for an ultrasonic fingerprint module, and a preparation method and application thereof. By optimizing the sintering type silver paste component, the sintering type silver paste has the advantages of low sintering temperature (100-120 ℃), high density, low touch (less than or equal to 3), low surface roughness (Rz <2 mu m), no layering after lamination, no large-size holes (> 1 mu m) and the like. In order to achieve the above purpose, the present invention provides the following technical solutions: According to the technical scheme, the ultralow-temperature sintering silver paste for the ultrasonic fingerprint module comprises, by mass, 2% -5% of saturated polyester, 0.1% -1% of a curing agent, 0.01% -0.5% of a saturated polyester modification auxiliary agent, 80% -90% of nano silver powder, 2% -10% of a solvent, 0.1% -2% of a dispersing agent, 0.1% -0.5% of a silver paste sintering auxiliary agent, 0.1% -1.2% of a coupling agent and 0.1% -1% of a thixotropic agent, wherein the saturated polyester is a large-molecular-weight linear saturated polyester with weight average molecular weight not less than 20000. Preferably, the saturated polyester includes at least one of aromatic saturated polyester, aliphatic saturated polyester and aromatic-aliphatic saturated polyester. Preferably, the curing agent comprises at least one of oxazoline, isocyanate, diisocyanate, and dicyanate prepolymer. Preferably, the saturated polyester modifying auxiliary agent comprises at least one of anhydride, organotin and acetylacetonate metal salt. Preferably, the nano silver powder comprises nano silver powder 1 with an average particle size of 50-150 nm and an irregular polygonal structure, wherein the silver content of the nano silver powder 1 is 90-95%, the average particle size of 200-300 nm, the powder is nano silver powder 2 with an irregular polygonal structure and an silver content of 90-95%, the average particle size of 200-400 nm, the powder is nano silver powder 3 with a sphere-like structure and an silver content of 90-95%