According to the nature and application of thick films, there are five types of pastes used: conductor, resistor, dielectric, insulating and encapsulation pastes.
Conductive pastes are used to make thick film conductors to form interconnect lines, multilayer wiring, microstrip lines, solder pads, thick film resistor terminations, thick film capacitor plates and low value resistors in thick film circuits.
Thick-film resistors are the earliest developed and highest-level thick-film components in thick-film integrated circuits, which can manufacture various resistors. The main requirements for thick film resistors are high resistivity, low temperature coefficient of resistance and good stability.
Like conductor pastes, resistive pastes also have three components: conductor, glass, and carrier. However, its conductor is usually not a metal element, but a compound of a metal element, or a complex of a metal element and its oxide. Commonly used pastes are platinum-based, ruthenium-based and palladium-based resistor pastes.
Thick film dielectrics are used to make miniature thick film capacitors. The basic requirements for it are large dielectric constant, small loss tangent, large insulation resistance, high withstand voltage, stability and reliability.
The medium slurry is made of low-melting glass and ceramic powder homogeneously suspended in an organic carrier. Commonly used ceramics are barium, strontium, calcium titanate ceramics. By changing the relative content of glass and ceramics or the composition of ceramics, dielectric thick films with various properties can be obtained to meet the needs of manufacturing various thick film capacitors.
Thick film insulation is used as an insulating layer for multilayer wiring and cross wires. The requirements for it are high insulation resistance, small dielectric constant, and the coefficient of linear expansion can be matched with other films. The solid powders commonly used in insulating pastes are alkali-free glass and ceramic powders.
