Printed Circuits—Origins and Development

he development of printed circuit technology is almost inseparable from the development of materials. Copper clad laminates could be said to have started with the discovery of phenolic resins by Dr Leo Baekeland in 1909. He found that by using catalysts he could control the speed and extent of the reaction of phenol with formaldehyde, suspending the reaction at any time to add reinforcements. Using resins in a liquid form he was able to combine them with wood cloth, paper or fibre to build an insulating material.