Function expansion device, manufacturing method thereof and electronic apparatus system

摘要

A function expansion device is electrically connected to an electronic apparatus by being inserted in a socket included in the electronic apparatus and expands a function of the electronic apparatus. The function expansion device includes a substrate on which a component is mounted, a first connecting terminal that is formed at an end portion of the substrate and is electrically connected to a first signal line that connects the electronic apparatus and the component in a one-to-one fashion, a second connecting terminal that is formed at the end portion of the substrate and is electrically connected to a second signal line that connects the electronic apparatus and the component redundantly, and a protection member that is formed to cover only the second connecting terminal.