|Figure 1: DDR test configuration|
for a desktop computer
|Figure 2: A typical DDR test setup|
for a netbook computer
|Figure 3: Using probe holders|
in reverse position
Figure 4 shows all three of the above techniques in use. The combination of the chip clip, probe holders, and gooseneck strain reliefs do an excellent job of preserving the integrity of the probe connections while probing DDR clock, strobe, and data signals.
|Figure 4: Deployment of chip clip, reverse probe holders,|
and gooseneck strain relief
If one were to be transporting such a test setup on a rolling cart within the same facility, it's a good idea to place an ESD bag underneath the DDR DUT for static protection. Using a cart is recommended as it provides support for the three probe-platform cable assemblies (one each for clock, strobe, and data lines). For extra security, one might anchor the assemblies to the card with cable ties, clips, or tape. Don't forget to carefully label probe tips with adhesive labels; the probe amplifiers will be disconnected during transport and the labels will help with reconnecting the probes. It's not a bad idea to label the probing points on the DUT as well.
Stay tuned for more best practices for eliminating DDR test pitfalls in future posts.