The Printed Circuit Story

Duration: 12:00

Year Published: 1961

Creator: The Bray Studios Inc. with the Institute of Printed Circuits

Complete Record: Films begins with a description of a Sonabuoy used by the Navy to detect submarines. The Sonabuoy is a transmitter and receiver mounted on a small circuit board. Developed during WW2. Circuit boards are used today in computers, radar, televisions, and various other electronic equipment, and missile guidance systems. “Printed circuits are simply electric conductors superimposed on an insulated material of a high pressure laminate.” There are various kinds of high pressure laminates: Paper, epoxy, fiber glass epoxy, Teflon, and others. All have various electrical and mechanical characteristics. The process of making of a high pressure laminate is shown in steps -- from (1) making of the paper, (2) attaching it to a copper sheet, (3) placing it in a hydraulic press where they are subjected to heat and pressure. They are inspected when finished. Then they are ready for stamping the circuits. This part of the film is taken in a factory and shows each step clearly: Men in lab coats, placement of sheets, views of machinery. The sheets are then shipped to a circuit board stamping plant. The images are now of this facility which has a testing lab which thoroughly checks out the uniformity of the sheets and their ability to conduct electrical current reliably. In the stamping area, we see large presses at which sits a worker. The first thing in stamping is putting in “position holes” and the sheets are given a thorough cleaning. All steps illustrated by workers and machines. The sheets then are subjected to an acid-resist transfer process. Silk-screening leaves the pattern of the type of circuit. Another method puts a light sensitive coat on the board which is spun dry under infrared light. Pattern transfer is then made through a photographic process and exposure to intense light in order to imprint the pattern. So a sheet in cross-section shows laminate, copper, and acid resist pattern. When put in an acid vat, the copper is dissolved leaving only the raised pattern on its of paper. This is known as a subtractive process. Images of steaming vats and baskets holding laminates being lowered and raised from vats. Smaller boards of various sizes are cut from the larger sheets, and holes are drilled to fit the various components. Workers shown doing these tasks with machines. More complicated tasks shown: Electroplating laminate to build up circuits, and multiple boards produced. Circuits boards are produced in various ways. Workers then add the circuits and capacitors are put on. Tube sockets and transistors are directly mounted on the board and soldered by workers at their desks. Large quantities of circuits can be dip-soldered by an acid resist process. Printed circuits have contributed to the standardization and reliability of circuits for electronic equipment. Testing and repair explained and illustrated. Tools for testing and repair are also described and shown. Procedural steps are shown close-up.