Twenty-five years of designing ferrites to achieve EMC in digital electronics

The enactment of Part 15J of the FCC regulations had a ground shift effect on the ferrite industry. Previous research and development efforts bad been focused on inductive applications for ferrite materials and little work was done to do more than apply available materials to control EMI problems. The mid 1970s were not a time of growth for the industry in the United States, since the manufacture of consumer electronics and component parts was rapidly moving to lower labor cost areas. The digital electronics age was just starting to develop as a market. Indeed, Part 15 was the cause of renewed growth in the ferrite industry. New shapes proliferated, and the range of sizes for EMI suppressors grew from less than a hundredth of a gram to several hundred grams. Even more important was the development of new materials that could meet the new challenge of controlling EMI.