Gold contact finish suits applications needing a few dozen mating cycles, like test fixtures or modular subassemblies that get swapped during service.
Pitch and Board Footprint — the 0.50 mm Reality
At 0.020" (0.50mm) pitch, this is a fine-pitch connector. The 20 positions across two rows means the PCB footprint is compact — roughly 5 mm along the mating edge. That pitch demands a controlled impedance layout if signals are fast, and the solder-paste stencil aperture needs to be matched to the 0.50 mm pad pitch to avoid bridging. The base product number 20P5.0-J tells you the position count and pitch directly: 20 positions at 5.0 mm overall row spacing.
Obsolete — What That Means for Sourcing
JST has marked the 20P5.0-JMCS-G-TF(N) as Obsolete. No factory orders are being accepted. If this part is on your BOM, the move is to either buy a lifetime buy quantity now or identify a replacement. A pin-compatible alternative would need the same 0.50 mm pitch, 20 positions, 2 rows, and 5 mm stacking height — a parametric search across JST's current board-to-board line is the next step.
Mating and Assembly Check
This is the plug side (outer shroud contacts) of a mezzanine pair. It mates with the JMC series receptacle — the one with inner contacts that fit inside this shroud. The 5 mm stacking height is the mated height, so the receptacle half must also specify 5 mm stacking height. Surface-mount only; no through-hole option.