Metallized Si3N4 Ceramic Substrate Manufacturer,silicon nitride ceramic metallizatio design for IGBT,Power Module
Silicon Nitrides (Si3N4) Feature An Excellent Combination Of Material Properties. They Are Nearly As Light As Silicon Carbide (SiC), But Their Microstructure Gives Them Excellent Thermal Shock Resistance And Their High Fracture Toughness Makes Them Resistant To Impacts And Shocks.
Properties Of Silicon Nitride (Si3N4)
Very Low Density (3.21 G/Cm3)
Very High Fracture Toughness (7 MPam1/2)
Good Flexural Strength (850 MPa)
Very Good Thermal Shock Resistance: High Thermal Stress Parameters (569 K)
Maximum Operating Temperature In An Oxidizing Atmosphere: 1,300°C
Maximum Operating Temperature In A Neutral Atmosphere: 1,600°C
High Strength (High Reliability)
Similar To The Thermal Expansion Coefficient Of Semiconductors Such As Si, SiC, And GaN
High Dielectric Strength
High Bending Strength
Main Use Of Precision Ceramics For Electronics (Si3N4=Silicon Nitride)
Power Module Substrates
Submount For Optical Pick-Up
Heat Dissipation Substrates
The porous silicon nitride ceramic material combines the excellent properties of both the silicon nitride ceramic and the porous ceramic and is a ceramic material having a communicating or closed pore in the body. Porous silicon nitride ceramics have been widely used in aerospace and environmental chemicals due to their special structure and properties, such as low density, high porosity, moderate dielectric properties, high specific surface area, high hardness, and high fracture toughness. Important fields such as biomedicine, national defense, and the military.
The pressureless sintering method is the most commonly used sintering method. It is based on α-Si3N4 under standard atmospheric pressure, and a certain amount of sintering aid is added for liquid phase sintering. During the sintering process, α-Si3N4 is converted into β-Si3N4. The structure of the silicon nitride crystal grains is transformed into an equiaxed crystal into columnar crystals, and the columnar crystals prevent the densification of the materials, and together, they form pores having different structures.
Advantages: The preparation process is relatively simple, the cost is low, and the prepared material has excellent performance.
Disadvantages: Pay attention to the composition design of raw materials and the adjustment of process parameters.
The hot press sintering method is a sintering method in which a uniaxial direction is heated while being pressed, and molding and sintering are simultaneously performed, which can accelerate the rearrangement and densification of the material.
Advantages: The prepared porous silicon nitride ceramic has high strength.
Disadvantages: high density, low porosity, good anisotropy of properties due to uniaxial pressing during sintering.
Forging and pressing
The forging and pressing method is a method for controlling the microstructure of a sintered body by adjusting the sintering process parameters and applying a certain mechanical pressure in a single direction after sintering and heat preservation.
Advantages: Both the advantages of ceramic preparation and metal processing.
Disadvantages: The porosity of the prepared material is low and the anisotropy problem in use needs to be considered.
Isostatic compression sintering
Isostatic pressing is designed according to the principle of fluid mechanics, and the pressure is transmitted uniformly and uniformly in all directions. It can be divided into cold isostatic pressing and hot isostatic pressing.
Advantages: the process is simple, and the prepared material is evenly organized.
Disadvantages: The low porosity of the product, while the high cost of investment equipment limits its further development.
The pore-forming agent is added by adding a certain amount of pore-forming agent to the ceramic body, usually, some organic substances which are heated and volatile, or acids, alkalis, salts, etc. which are easily decomposed to generate the gas at a high temperature, and the pore-forming agent is in ceramics. The blank will occupy a certain volume, and the pore-forming agent or organic matter in the green body is discharged through the debinding and sintering process to finally form a porous ceramic.
Advantages: The method has a simple process and many kinds of pore-forming agents, and can control the porosity and pore structure of the porous ceramic by adjusting the addition amount and shape of the pore-forming agent.
Disadvantages: The porous ceramics prepared by the method have poor pore distribution uniformity and large pore size, and large pores can seriously affect the mechanical properties.
The tape casting method is a molding process in which a slurry is scraped into a certain thickness on a flat carrier tape to form a film blank, and then the sheet blank is laminated and cut according to the required sample shape and size. Porous ceramics are obtained by sintering.
Advantages: simple process, high production efficiency, and a good economy.
Disadvantages: The prepared porous silicon nitride ceramics can only meet the application under certain conditions due to the existence of anisotropy, and the porosity is low and it is difficult to prepare components with complicated shapes.
Porous silicon nitride ceramics are obtained by sintering at a certain temperature by a carbothermal reduction method using relatively inexpensive raw materials such as silica, carbon powder, silicon powder, and the like.
Advantages: low cost and practicality.
Disadvantages: The phase composition of the prepared porous silicon nitride ceramic is relatively complicated, the porosity is difficult to control and the strength is relatively low.
Gel injection molding
The method combines polymer chemistry and traditional ceramic process and uses the organic monomer and the cross-linking agent inside the slurry to polymerize under the action of the initiator, thereby fixing the powder, and then discharging and sintering in the next step. In the process, organic matter is excluded, and porous ceramics having uniform pore distribution, high porosity, and high strength are formed.
Advantages: simple equipment, the uniform composition of the blank body, uniform density, and fewer defects.
Disadvantages: Dry conditions and debinding processes are not easy to control.
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