What This 60-Position Mezzanine Receptacle Does in the Stack
Stack Height Flexibility — One Footprint, Four Board Spacings
The variation comes from the header side — the receptacle stays constant, so a single BOM line for the 5177985-2 covers multiple stack heights if you swap the mating header. That simplifies inventory for designs that share a main board but vary the mezzanine card spacing.
The gold layer resists oxidation and fretting corrosion better than tin, which matters in a mezzanine stack that may be unmated for rework or testing. The 60 positions at 0.80mm pitch mean the contact force per beam is modest — the gold finish ensures stable contact resistance over the connector's service life.