Second source

In the electronics industry, a second source is a company that is licensed to manufacture and sell components originally designed by another company (the first source).^[1]

It is common for engineers and purchasers to avoid components that are only available from a single source, to avoid the risk that a problem with the supplier would prevent a popular and profitable product from being manufactured. For simple components such as resistors and transistors, this is not usually an issue, but for complex integrated circuits, vendors often react by licensing one or more other companies to manufacture and sell the same parts as second sources. While the details of such licenses are usually confidential, they often involve cross-licensing, so that each company also obtains the right to manufacture and sell parts designed by the other.