0.40mm Pitch Mezzanine Receptacle for 4mm Stack Height
The Hirose DF40TC(4.0)-30DS-0.4V(58) is a 30-position receptacle from the DF40T series, designed as the bottom-side mezzanine connector in a board-to-board stack. It uses a 0.016" (0.40mm) pitch dual-row layout with center strip contacts, and its key dimensional spec is the 4mm mated stacking height — that's the gap between the two PCBs when mated with the matching DF40T header.
At 0.40mm pitch, the footprint demands a PCB capable of routing traces between pads — standard 0.5mm-pitch processes won't clear the escape routing without micro-vias or tighter design rules. The dual-row, 30-position layout means the connector body is roughly 7.5mm long, so the keep-out zone on the board is compact. The SMT solder retention pads help hold the part during reflow and add some shear strength against the mating force of the header.
Position Count vs. Siblings
The 30-position DF40TC(4.0)-30DS-0.4V(58) sits between the 20-position DF40TC(4.0)-20DS-0.4V(58) and the 40-position DF40TC(4.0)-40DS-0.4V(58) in the same 4mm stack-height variant.
Stack Height Variant: 4.0 vs. 3.5
The DF40TC(4.0)-30DS-0.4V(58) is the 4mm stack-height version. The sibling DF40TC(3.5)-30DS-0.4V(58) uses a 0.134" (3.40mm) height and mates to a different header to achieve a 3.5mm stack. If your board-to-board z-budget is 4mm, this is the correct receptacle; the 3.5mm version won't reach the header contacts in a 4mm stack. The pitch, position count, and plating are identical.