The specification describes PDA (SD/MMC) devices and PDA cards wherein the substrate on which the PDA components are mounted comprises two tiers. Components with a high profile are mounted on the lower tier, and devices with normal or low heights are mounted on the upper tier. The upper tier is contained in the portion of the card conforming to, for example, the 1.4 mm SDA standard thickness, while the lower tier is formed in the portion of the card that allows a larger thickness, for example SDA standard thickness 2.1 mm.