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CN-122025217-A - Conductive silver paste containing photosensitive active boroaluminate glass

CN122025217ACN 122025217 ACN122025217 ACN 122025217ACN-122025217-A

Abstract

The invention discloses conductive silver paste containing photosensitive active boroaluminate glass, and belongs to the technical field of electronic materials. The chemical composition of the photosensitive active boroaluminate glass comprises, in terms of mole percent of oxides, 45% -65% of B 2 O 3 %, 5% -30% of Al 2 O 3 , 1% -25% of PbO, 1% -10% of Bi 2 O 3 and specific types of transition metal oxides. The glass has excellent absorption capacity to laser with wavelength of 806 nm-1064 nm, and can efficiently convert light energy into heat energy. The conductive silver paste is prepared by taking the powder of the glass as a key functional phase and matching with silver powder, an organic carrier and optional additives. The conductive silver paste disclosed by the invention is matched with a laser-assisted sintering process, so that local, rapid and low-temperature sintering of the electrode can be realized, and the formed electrode is compact, low in sheet resistance and strong in adhesive force, and is particularly suitable for the fields of printed electronics, photovoltaic cell metallization contact and the like.

Inventors

  • LI HUIXIN
  • SUN XINJIE
  • ZHOU YINGYING

Assignees

  • 上海惟德络新材料科技有限公司

Dates

Publication Date
20260512
Application Date
20260210

Claims (10)

  1. 1. An electrically conductive silver paste comprising a photosensitive active boroaluminate glass, characterized by: the conductive silver paste takes a photosensitive active boroaluminate glass powder as a key functional phase and comprises silver powder, an organic carrier and optional additives; the chemical composition of the boroaluminate glass powder comprises the following components in mole percent of oxide: B 2 O 3 :45%-65%, Al 2 O 3 :5%-30%, PbO:1%-25%, Bi 2 O 3 :1%-10%, 1% -10% of transition metal oxide, one or more selected from FeO、Fe 2 O 3 、Fe 3 O 4 、MnO、Mn 2 O 3 、MnO 2 、WO 2 、MoO 3 、CuO、Cu 2 O、Ag 2 O; The total amount of other metal oxides is 0% -5%, and one or more of CaO、MgO、SrO、BaO、NiO、SiO 2 、SnO 2 、TiO 2 、TeO 2 、ZrO 2 、ZnO、Li 2 O、Na 2 O、K 2 O、Y 2 O 3 、Ga 2 O 3 、P 2 O 5 、Nb 2 O 5 are selected.
  2. 2. The conductive silver paste containing photosensitive active boroaluminate glass according to claim 1, wherein the composition comprises, in mass percent: 0.5 to 5 percent of boron aluminate glass powder, 80 To 92 percent of silver powder, 5 To 15 percent of organic carrier, 0% -2% Of inorganic powder or metal powder additive.
  3. 3. The conductive silver paste of claim 1, wherein the median particle size D50 of the boroaluminate glass powder is 0.5 μm to 3.0 μm.
  4. 4. The conductive silver paste containing photosensitive active boroaluminate glass according to claim 1, wherein the silver powder is one or a combination of more of spherical silver powder, flake silver powder and dendrite silver powder, and the D50 particle size of the silver powder is 0.5-5 μm.
  5. 5. The conductive silver paste containing photosensitive active boroaluminate glass according to claim 1, wherein the organic carrier is composed of an organic solvent, a resin and a leveling agent, wherein the organic solvent is one or more selected from terpineol, diethylene glycol butyl ether acetate and butyl carbitol acetate, and the resin is one or more selected from ethyl cellulose, acrylic resin and nitrocellulose.
  6. 6. The conductive silver paste of claim 1, wherein the inorganic powder or metal powder additive is one or more of alumina, silica, titania, zinc oxide, nickel powder, silicon powder, aluminum silicon alloy powder, copper powder.
  7. 7. The conductive silver paste containing photosensitive active boroaluminate glass according to claim 1, wherein the conductive silver paste is subjected to auxiliary sintering by using a laser having a wavelength of 808nm to 1064nm after being printed or coated to form an electrode pattern.
  8. 8. A method of preparing an electrically conductive silver paste comprising a photosensitive active boroaluminate glass according to claim 2, comprising the steps of: Step 1, preparing the glass composition according to claim 1, and obtaining photosensitive boroaluminate glass powder through melting, water quenching, crushing, ball milling, drying and sieving; Step 2, mixing the photosensitive boroaluminate glass powder, the silver powder and the optional inorganic powder or metal powder additive, and placing the mixture into mixing equipment to be fully and uniformly mixed to obtain mixed powder; And step 3, stirring, rolling and dispersing the mixed powder obtained in the step 2 and the organic carrier to obtain uniform slurry.
  9. 9. Use of an electrically conductive silver paste comprising a photosensitive active boroaluminate glass according to claim 2 for laser assisted sintering, wherein after patterning the electrically conductive silver paste on a substrate, the pattern is scanned with a laser having a wavelength of 808nm, 915nm, 980nm or 1064nm for localized sintering.
  10. 10. The use of a conductive silver paste comprising photosensitive active boroaluminate glass according to claim 9, wherein the substrate is a thermally sensitive flexible substrate or a crystalline silicon solar cell, the thermally sensitive flexible substrate is a polyimide, polyethylene terephthalate or polyethylene naphthalate substrate, and the crystalline silicon solar cell comprises PERC, TOPCon, HJT structures.

Description

Conductive silver paste containing photosensitive active boroaluminate glass Technical Field The invention relates to the technical field of electronic materials, in particular to a slurry which contains a photosensitive active boroaluminate glass functional phase and can be sintered to form a conductive pattern by laser assistance. The invention is especially suitable for preparing high-precision and high-performance conductive patterns on heat-sensitive substrates (such as polymer flexible substrates), and can also be used for improving the contact performance and conversion efficiency of electrodes in devices such as crystalline silicon solar cells and the like. Background As a key electronic functional material, the conductive silver paste generally has a core composition including silver powder as a conductive functional phase, inorganic glass frit as a binder phase, and an organic vehicle providing rheological properties. It is widely used in thick film integrated circuits, multilayer ceramic devices, solar cell electrodes, touch screen sensing layers and various flexible electronic devices. In these applications, the silver paste needs to perform its function by a sintering process in which the organic carrier is volatilized and decomposed initially, and then the glass frit softens, melts, wets and bridges the silver powder particles to form a dense conductive network while forming a strong chemical or mechanical bond with the substrate (e.g., silicon wafer, ceramic, glass or polymer). Conventional sintering of conductive silver paste generally relies on a wholly heated sintering furnace, requiring heat treatment at high temperatures of 500 ℃ to 850 ℃. Such a high temperature process is not at all affordable for a substrate having poor heat resistance, particularly a polymer substrate such as Polyimide (PI), polyethylene terephthalate (PET), polyethylene naphthalate (PEN) or the like used in flexible electronics which have been rapidly developed in recent years, and may cause deformation, yellowing, degradation or even burning of the substrate. In addition, integral furnace sintering has the inherent limitations of high energy consumption, long process time, incapability of repairing local patterns, selective sintering and the like. To break through these limitations, laser sintering techniques have been developed and widely studied. This technique uses a high energy density laser beam (typically in the near infrared band, such as 808nm, 915nm, 980nm, 1064 nm) to locally scan heat a pre-printed shaped silver paste pattern. Because of its high concentration of energy and short duration of action, rapid localized sintering of the silver paste pattern can be achieved while the overall temperature of the substrate can be maintained at very low levels (e.g., below 150 ℃) so as to be perfectly compatible with flexible and thermally sensitive substrates. In the field of crystalline silicon solar cells, technologies such as Laser Enhanced Contact Optimization (LECO) and the like have also been developed, and ohmic contact between an electrode and a silicon substrate is improved by laser local energy injection, so that open-circuit voltage, short-circuit current and final conversion efficiency of the cell are improved. However, the successful application of laser sintering technology to conventional conductive silver pastes presents a key challenge in that the absorptivity of the conventional glass binder phase (typically lead borosilicate, bismuth borosilicate, etc. systems) in silver pastes is generally low for near infrared band lasers. This means that most of the laser energy will penetrate the silver paste layer or be reflected and not be effectively used to heat and melt the glass phase. In order to achieve the necessary sintering effect, a high laser power is often required, but this causes a series of problems such as splashing of silver powder due to overheating (causing line discontinuity and short-circuit risk), damage of the substrate surface due to thermal shock or overheating (which is particularly serious for the polymer substrate), and high processing cost due to low energy utilization efficiency. Therefore, developing a functional glass powder with high absorptivity and high photo-thermal conversion capability to near infrared laser, and preparing the conductive silver paste special for laser-assisted sintering by taking the functional glass powder as a core becomes a key for pushing the technology to large-scale industrial application. The glass powder needs to be capable of acting as an efficient 'micro heat source' under laser irradiation, rapidly converting light energy into heat energy, and melting local glass phase in a very short time, so that densification sintering of silver paste and firm adhesion with a substrate are realized under mild conditions of low laser power and low substrate overall temperature, and meanwhile, thermal damage to silver powder and the substrate is avoided. D