0.40mm pitch, 20 positions, 3mm stack — what that buys the layout
The Hirose DF40TC(3.0)-20DS-0.4V(58) is a 20-position receptacle from the DF40T series, built for board-to-board mezzanine stacking at a 3mm mated height.
3mm vs 3.5mm stack — picking the right height variant
The DF40TC(3.0)-20DS-0.4V(58) mates to a 3mm stack. The sibling DF40TC(3.5)-20DS-0.4V(58) shares the same 20 positions, 0.40mm pitch, gold flash, and dual-row layout, but its mated stacking height is 0.134" (3.40mm). That 0.40mm difference is the only meaningful delta — the board-to-board z-budget decides which one lands on the BOM. Everything else (footprint, terminal, plating) is identical, so swapping between them is a board stack-up call, not a re-layout.
Sourced to order — active, no LTB pressure
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