|Figure 1: The anatomy of a chip interposer|
|Figure 2: This series of photos illustrates how the interposer|
brings out the DDR BGA's I/Os to make them
accessible to test probes.
|Figure 3: Be careful when using interposers with DDR|
DIMMs. Avoid using them on the chips in the end
locations, where they may interfere with latches.
In addition to the aforementioned strategy regarding DIMMs, another "best practice" for testing with interposers is to use tweezers to manipulate probe tips when soldering. Tweezers are more nimble than most peoples' fingers, providing better placement and accuracy during the soldering process.
Another tip: Solder probe tips to the interposer in advance. It's easier than when the interposer is in place, and the soldered-in tips can be switched in and out as necessary for connection to a probe amplifier.