What is the abbreviation for materials which is commonly used to create printed circuit boards (PCBs)? It describes the green fiberglass-and-epoxy laminate that every printed circuit board is built on - rigid, heat-resistant, electrically insulating board on which conductors can be printed. Its name is just two letters and a digit and the two letters stand for a material property.

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Answer to yesterday's question: Inventor Leo Baekeland named this material after himself as "Bakelite". Bakelite is considered the first truly synthetic plastic — just phenol and formaldehyde reacting under heat and pressure. Its heat resistance and electrical insulation made it especially valuable for the booming electrical industry.