This question is summarized from a discussion on the Electrical Engineering StackExchange chat.
It is reproduced here in hopes to generate a discussion with long-term value
Question for anyone with experience with long (> 30 years) life cycle product design:
Do you generally design keeping in mind possible obsolescence / discontinuation of key parts within the life-cycle of the product?
Specifically, if a pin-compatible equivalent for a specific IC is no longer made, how is that planned for? Not every semiconductor manufacturer does lifetime buy notifications by package, and some manufacturers simply fold up and disappear.
The context here is of a product for which my client has over 100k PCBs in inventory, and more than 2 million devices deployed over 30 years. A couple of the key parts used on the board no longer exist, and near equivalents are all SMT. All ICs on the original boards are DIP and socketed. Some of the ICs in question are obsolete analog continuous-time signal processing parts, the rest are digital logic and thus easily substituted by equivalents, ASICs or MCUs depending on complexity.
There's a repair workstream (industrial product, 20 to 30 year serviceability warranties), and there is a production workstream (repeat orders, thousands of boards per year).
Respinning the board, while an ideal suggestion, is not an option in this case, as the Purchases department of the end-customer would consider a base PCB change as a "new product", hence requiring evaluation of competing vendors, and renegotiation of the contract - This will trigger a fresh tendering process and potentially loss of 10x millions worth of annual business for my client, to a competitor.
Current repairs of customer-site devices are all done by manual reworking in the field, the device is not allowed to be brought back to a workshop. Replacement of boards does happen, but the "new" replacement board absolutely must be identical in PCB layout to the one being replaced, as the end customer does not take kindly to any changes.
A proposal being considered, though yet to be validated with the end customer's purchases team, is replacement of DIP ICs with identically sized little PCBs with pins, plugged into the DIP sockets on the main board. This is intended to reduce field-work risks and time.
So, back to the question: What are practical EE experiences in planning for such product lifecycles and associated challenges? Great ideas for "next time" are also welcome.