25 Apr 2016: EOMA68-jz4775 X-Ray photos
When the first 6 samples were done, only one was found to be working: for some reason the DDR3 BGA solder balls had spread and caused short circuits. One of the samples was still with the factory, and that too was found to have shorts. Mike has been extremely helpful, and this is the first time that he's been involved with BGA, where his uncle's factory has been the one that assembled the samples.
So it made sense to ask Mike if he could redo the DDR3 ICs on that one sample that he has, then X-Ray them, to get some experience with the process. The results are below, and are as fascinating as they are perfect. What looks like fuzzy dark blobs across the pins and vias on the top layer of the jz4775 SoC is in fact the out-of-focus components from the bottom layer: mostly these are capacitors for the power planes.
So this is good news: chances are high that there are now two working EOMA68-jz4775 Revision 2.2 samples in the world.
Posted Mon 25 Apr 2016 11:01:14 BST
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