Before you come to us.
Make sure the part is truly unobtainable or is too expensive. Many parts although made obsolete by the manufacturer are still available from other suppliers. Check on the Internet, talk to some of the IC brokers.
Some parts may not be available in the correct package. There are a number of companies who specialise in package converters to help. look at:
Some parts may be available at higher speeds and wider specifications or from a different manufacturer.
Only if there is no other source should you come to us. We aim to keep you manufacturing for as long as you require.