Second source

In the <a href="/facts/Electronics_industry/YX8VCvKC">electronics industry</a>, a second source is a company that is licensed to manufacture and sell components originally designed by another company (the first source).
It is common for engineers and purchasers to seek components that are available from multiple sources, to avoid the risk that a problem with one supplier would prevent a product from being manufactured. For simple components such as resistors and transistors, this is not usually an issue, but for complex <a href="/facts/Integrated_circuit/fjn6vg7C">integrated circuits</a>, 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 <a href="/facts/Cross-licensing/g3axjcQw">cross-licensing</a>, so that each company also obtains the right to manufacture and sell parts designed by the other.
In the early TTL device period wafers were smaller so production was limited. More production lead to lower prices and new designs rapidly emerged.

Second source open-in-new

Second source