PCB retainers for defence and aerospace sectors

The retainers incorporate a patent-pending torque-limiting feature that enables a PCB assembly to be fixed into a chassis at a prescribed clamping force without the need for a torque wrench.

The five-wedge devices are designed to prevent damage to the PCB or to the Card-Lok itself due to over-tightening.

By turning the centre screw clockwise, the outer wedges are drawn together, forcing the centre wedge sections to expand outwards.

When the turning force exerted on the screw reaches the preset torque, the built-in ratchet clutch disengages with an audible click to prevent further tightening.

The series 223 and 224 retainers generate a minimum clamping force of 1200N when torqued.

As well as providing maximum resistance to shock and vibration, the Card-Loks also play a role in dissipating heat from the PCB.

The devices feature a lightweight aluminium construction and can be specified with various finished, including black anodised, electroless nickel and chemical film.

They are available with profiles of either 5.72 x 6.60mm (series 223) or 5.33 x 6.99mm (series 224) in a range of standard lengths from 121.9mm to 329.9mm.

The Card-Loks are manufactured by Calmark, one of Schroff's sister companies within the Pentair Technical Products Group.