A silver conductor paste with a wide range of applications. For example: chip resistors, potentiometers, and heaters.

Piezoelectric ceramics are information functional ceramic materials that can convert mechanical and electrical energy into each other. They have been widely used in medical imaging, acoustic sensors, ultrasonic motors, ultrasonic transducers, underwater acoustic transducers, electroacoustic transducers, ceramic filters, ceramic transformers, ceramic frequency detectors, high-voltage generators, infrared detectors, surface acoustic wave devices, electro-optical devices, ignition and detonation devices, and piezoelectric gyroscopes; In the manufacturing process of piezoelectric ceramics, the surface needs to be treated with silver, and then polarized to obtain piezoelectric ceramic products with specific properties; At present, screen printing or manual coating with silver layer sintering and infiltration process is widely used.
Most piezoelectric ceramic devices vibrate within the frequency range of several kilohertz to several hundred megahertz during use, so the bonding strength between the silver electrode layer and the substrate should be strong enough to avoid the silver electrode detaching from the substrate during application and causing component failure or damage; During the manufacturing process of piezoelectric ceramic devices, it is necessary to solder leads onto the silver electrode layer Silver electrode weldableExcellent welding resistance; The surface flatness and density of silver electrodes also greatly affect the electrical performance of piezoelectric devices. Traditional silver paste for piezoelectric ceramics is composed of silver powder, glass powder, organic carrier, and additives; Silver powder is generally spherical silver micro powder, and glass powder is generally made of borosilicate lead glass. The lead element content in glass powder is high, which seriously pollutes the environment and endangers human health. In recent years, functional ceramics have been used Lead free electrode silver paste pasteThe number of patents continues to increase, but none of them indicate their use on piezoelectric ceramic substrates, and there is a problem of non universality of electrode silver paste on different piezoelectric ceramic substrates; Some electrode silver paste patent glass powders are lead-free and cadmium free, but often contain a large amount of alkali metal elements, which can damage the reliability and stability of the silver paste.

Technical implementation elements: The present invention provides a Silver paste for general lead-free piezoelectric ceramicsThe formula and its preparation method should at least solve the problem of lead in piezoelectric ceramic silver paste that cannot be universally used in existing technology. The present invention provides a universal lead-free piezoelectric ceramic silver paste, which comprises the following weight parts of raw materials: 45-75 parts of silver micro powder, 0.1-5 parts of additives, 0.5-10 parts of lead-free glass powder, 0.5-5 parts of additives, and 15-40 parts of organic carrier. Furthermore, the lead-free glass powder comprises the following weight parts of raw materials: 40-60 parts bismuth oxide, 10-25 parts silicon oxide, 5-15 parts calcium oxide, 1-10 parts aluminum oxide, 0-15 parts boron oxide, and 0-5 parts zinc oxide.
Furthermore, the organic carrier comprises the following weight parts of raw materials: 3-15 parts of adhesive and 70-95 parts of solvent. Furthermore, the adhesive is one or more of ethyl cellulose, nitrocellulose, carboxymethyl cellulose, polymethacrylate, polyvinyl alcohol, rosin, and polyvinyl butyral; The solvent is one or more of turpentine alcohol, pineol, butyl carbitol, and acetone.
Furthermore, the auxiliary agent comprises the following weight parts of raw materials: 0.5-5 parts of slurry thixotropic agent, 0.5-5 parts of surfactant, and 0.5-3 parts of slurry dispersant. Furthermore, the slurry thixotropic agent is one or more of dimethyl phthalate, hydrogenated castor oil, and polyamide wax; The surfactant is one or more of phospholipids, stearic acid, polysorbates, and quaternary ammonium compounds; The slurry dispersant is modified polysiloxane. Furthermore, the silver micro powder is one or both of ultrafine silver powder and flake silver powder. The ultrafine silver powder is one or two of spherical or quasi spherical silver powder bodies; The median particle size d50 of the silver micro powder is 0.5-1.5 μ m, and the tap density of the silver powder is above 2.5g/cm3; The maximum particle size of the silver micro powder does not exceed 3.5 μ m. Furthermore, the additive is a metal oxide powder with a median particle size of 0.5-1.5 μ m and analytical purity or higher; Furthermore, the additive is one or more of CuO, ZnO, WO3, Bi2O3, MnO2, SiO2, Ta2O5, and Y2O3.

A universal type Silver paste for lead-free piezoelectric ceramicsThe preparation method includes the following steps:
s1， Preparation of lead-free glass powder involves mixing raw materials, melting at 1100-1200 ℃ for 1-2 hours, quenching in deionized water, and ball milling with alcohol until the glass powder particle size is less than 5um to obtain lead-free glass powder;
s2， Preparation of organic carrier: Mix the raw materials, heat and stir at 80 ℃ until completely dissolved to obtain the organic carrier;
s3， Slurry manufacturing involves mixing silver micro powder, additives, lead-free glass powder of s1, and organic carrier of s2, stirring and grinding until the fineness is less than 10um, to obtain the universal lead-free piezoelectric ceramic silver slurry of the present invention.
Compared with the prior art, the present invention adopts a bismuth silicon boron aluminum glass system instead of traditional lead containing glass to achieve lead-free products. The glass system can undergo mild reactions with the piezoelectric ceramic substrate, forming a strong interface between the electrode and the substrate. The organic carrier of the present invention has good printing properties such as thixotropy, dispersibility, and leveling, which can improve electrode flatness and structural density. It can be used universally on different piezoelectric ceramic substrates, and the present invention improves the environmental performance of the product.