Barbed legs compress as they pass through the hole and spring out behind it.

The leg is moulded with a taper and a shoulder. Pushing it through squeezes the barbs inward; once clear, they return and bear on the far face.

The board end works the same way, or uses a locking head that flexes as the board is pushed on.

Retention comes from the barbs bearing against the panel, so it depends entirely on panel thickness and hole size.

No tool is needed in either direction of assembly, which is the whole point.

The mechanism is a moulded plastic spring, so it is sensitive to temperature and to long-term creep.

Because retention depends on the barbs springing out fully behind the panel.

A hole slightly too large lets the barbs sit only partly engaged, and the standoff pulls back out under modest load.

A hole too small prevents the standoff seating, so it stands proud and the board sits at an angle.

Each part is rated for a specific hole diameter, and the tolerance is much tighter than for a clearance hole.

Panel thickness has its own stated range, since the barbs must clear the far face without excessive slack.

Deburring matters, because a burr can hold the barb open or damage it during insertion.

Some types yes, by squeezing the barbs; others are effectively one-way and are cut off.

Locking-head types are usually designed to release when the head is compressed, so a board can be lifted off.

Arrowhead types are generally intended as permanent and resist removal by design.

Reverse-mount and release-tab variants exist specifically for serviceable assemblies.

Cutting a standoff off is quick but leaves the chassis needing a replacement fitted from the accessible side.

Which behaviour is wanted should be decided at design stage, since it is not changeable afterwards.

The board's own weight, connector insertion forces and moderate vibration - not impact or real mechanical load.

Retention force is published per part and is modest compared with any threaded standoff.

Insertion and removal of connectors is the load most often underestimated, particularly on edge connectors.

Sustained vibration works the barbs against the hole and can wear the engagement.

Equipment that is dropped or transported roughly is better served by threaded standoffs.

Using more standoffs distributes load and reduces board flexing, which matters more than the rating of any one.

Moulded polymer versions do, and in many designs that is a requirement rather than a convenience.

A nylon standoff separates the board's mounting hole from the chassis both mechanically and electrically.

Where the mounting hole is a deliberate ground connection, an insulating standoff is the wrong part.

Board designs commonly mix grounded and isolated mounting points, so the standoff type must follow the design intent at each hole.

Polymer choice also affects flammability rating, which is frequently specified in electronics enclosures.

Metal snap-in fasteners exist for grounded mounting, with different retention behaviour.

Polymers creep under sustained load and soften with heat, so retention falls over time and with temperature.

A standoff holding a board against constant load will relax gradually, and the assembly loosens.

Elevated temperature accelerates it substantially, and equipment enclosures run warmer than the room.

Nylon also absorbs moisture, which changes its dimensions and stiffness slightly.

Glass-filled and high-temperature grades resist both effects better at higher cost.

Where the assembly must stay tight for many years at temperature, threaded standoffs are more predictable.

Wherever the assembly is serviced often, carries real load, vibrates, or must be grounded.

Repeated removal wears snap-in barbs and eventually loses retention.

Any load beyond board weight and connector forces is outside what they are made for.

Sustained vibration and transport shock both favour a threaded fixing.

A grounded mounting hole needs a metal fastener, which rules out moulded snap-in types.

The reverse case is equally clear: for a light board in volume production that is rarely opened, snap-in standoffs remove parts, tools and time.