Board-to-Board Mezzanine Stacking with the DF40TC
The Hirose DF40TC(3.5)-20DS-0.4V(51) is a 20-position, 2-row receptacle with center strip contacts, part of the DF40T series of fine-pitch board-to-board mezzanine connectors. It is designed for parallel PCB stacking at a fixed 3.5 mm mated height, with a 0.40 mm pitch that packs 20 signal lines into a compact footprint. The gold-plated contacts and SMT termination suit high-density digital interfaces where signal integrity and reliable mating are critical — think camera modules, display drivers, or compact processor boards in handheld or portable equipment.
Stack Height and Footprint — What the 3.5 mm and 0.40 mm Pitch Mean
The 20 positions in two rows give a 10-per-row layout; the receptacle's center strip contacts are mirrored on the mating plug, so the board layout must match the plug's footprint exactly.
SMT Assembly — Pick-and-Place and Solder Retention
Contact Finish — Gold Flash for Limited-Cycle Mezzanine Duty
In a mezzanine stack that is mated once at board assembly and rarely unmated, this is adequate. For applications requiring frequent reconnection or hot-plug duty, a thicker gold plating would be needed; this connector is designed for a fixed, low-cycle interconnect.