The flash storage looks flip-chipped onto the substrate, with the solder points on the front side. We are taken aback by the unusual, irregular pattern.
The experts at Creative Electron tell us that by looking at the patterning on the chip itself, focusing on the directions of the connections and vias, it looks like this board is made of four layers—two signals, power, and ground.
Taking a closer look at the balls that connect the chip, we notice a few light-colored bubbles within. This is called voiding.
Most contacts between boards are copper. But because copper oxidizes (rusts) very quickly, you have to wash it with an acid before making the bond. This acid is called flux and is used to "wet" the solder to the metal pads. Voiding happens when the flux isn't completely cleaned off.
Depending on its extent, this can be bad for durability. Clean, even connections allow heat to dissipate, while voiding allows for heat build up, reducing the life of components.
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