Mobile ion diffusion causes a shift in the threshold voltage of non-volatile storage elements in a memory chip, such as during an assembly process of the memory chip. To reduce or avoid such shifts, a coating can be applied to a printed circuit board substrate or a leader frame to which the memory chip is surface mounted. An acrylic resin coating having a thickness of about 10 μm may be used. A memory chip is attached to the coating using an adhesive film. Stacked chips may be used as well. Another approach provides metal barrier traces over copper traces of the printed circuit board, within a solder mask layer. The metal barrier traces are fabricated in the same pattern as the copper traces but are wider so that they at least partially envelop and surround the copper traces. Corresponding apparatuses and fabrication processes are provided.