Coatings and Thick Films

Abstract

The term “thick film” does not just refer to film thickness but rather to layers or a coating made by certain processing techniques. Most of the methods that we describe in this chapter involve suspending ceramic particles either in a solution or in a mixture of organic solvents (known as the vehicle). It will be necessary to remove all the volatile material from the coating to produce a dense adherent ceramic layer. Many of the processes described in this chapter are relatively inexpensive (at least compared to those used to produce thin films that we describe in Chapter 28) and simple.

Tape casting is used to produce flat sheets of many different ceramics for applications as substrates, capacitor dielectrics, and fuel cell electrolytes. Some of the techniques described in this chapter, for example, spin coating, are useful only for producing films on flat substrates. However, dip coating and electrophoretic deposition can be used to coat complex shapes. We finish by describing how thick-film circuits are made. In this application the ceramic is used as the substrate onto which the films are deposited and as important ingredients of the pastes that are used to form the circuits. The principle of the technology is not difficult, but controlling the processes may be.

All of these techniques are important in industry and you should know the language of thick films, e.g., slurry, slip, and paste.