The term printed circuit board (usually abbreviated to PCB), which is synonymous with the term printed wiring board (or PWB), is used to describe a substrate which provides mechanical support and the necessary electrical connections for an electronic circuit. Printed circuit boards have become an almost universal medium upon which electronic circuits are assembled. This makes the ability to manufacture high quality printed circuit boards an essential requirement. Printed circuit board technology has evolved relatively little compared with the other technologies used in the rapidly evolving electronics industry. The electronics industry has a distinct resistance to the introduction of alternative interconnection technologies to the printed circuit board. Some of the reasons for this resistance and hence the almost universal usage of printed circuit boards are as follows.