One of the biggest challenges we face in the replacement of obsolete parts is replacing the obsolete packages. We can re-create designs and implement them in new technologies, but we don't have the same flexibility for the packages. And while newer packages are easily available, there may be engineering or regulatory reasons why we cannot change the existing PC board to accommodate a newer package.
If a given package is not offered by one of our main assembly vendors, we first search to see if anyone else in the world offers it. The initial step is to look at their web sites and see what they offer. This is harder than it seems. The web sites may not be in English, and they may not be updated. We have frequently inquired, only to find that a specific package is no longer offered. The contact information is also challenging. And a given vendor may not be interested in what is for them a very small piece of business.
The cost is frequently higher from smaller vendors. Many have optimized their business around military work, and that can result in an increase of $20 per part to cover the packaging alone.
Some packages are just not obtainable. In those cases, we have to build an adapter card. We have used adapter cards for 56-pin SDIPs, 84-pin PGAs, and 84- and 132-pin BQFPs.
We have a R&D program underway that is looking into two different replacements for PLCC packages. One involves a special adapter card. The other uses a special LGA (Land Grid Array) package with a footprint created to fit the existing PLCC footprint. In both cases, our first step is to check the reliability of the cards. We have created parts with pairs of pins shorted inside of the package. This allows us to create PC boards that are a huge continuity chain. We will subject these boards to thermal cycling, and see if any of the cards develop opens.
If none do, we will build up product in these solutions, and go to a second step of reliability lifetime tests. And if these pass, we will begin trials with select customers. And if all goes well, we will offer these as solutions for obsolete packages.