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Schroff has launched the Calmark series 223 and 224 Card-Lok PCB retainers, which are targeted at cold-plate heat-transfer applications in the 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.

For over four decades Schroff has been a world leader in the development and manufacture of electronics packaging components and systems.


The company offers a comprehensive range of enclosure solutions, including cabinets, subracks, cases, backplanes and power supplies, as well as complete systems for standard bus architectures such as VME, cPCI, AdvancedTCA and MicroTCA.


These products are based on the know-how of specialists in the integration of mechanical, electronic and thermal management systems, together with many years’ experience of the most diverse applications in all kinds of environments. Schroff technical personnel are also heavily involved in the development of international standards for electronics packaging systems, with representatives on numerous working groups of institutions such as the IEC, CENELEC, IEEE, BSI, VDE and DIN.


To complement its wide range of products, the company has established a co-ordinated service strategy designed to ensure that customers enjoy comprehensive support throughout the life of the product.Grouped together under the banner ‘ServicePLUS’, Schroff’s product support services are now arranged in eight modules comprising configuration, assembly, modification, solution, express, support, academy and lifecycle.


The Schroff website, provides full technical information on all of the company’s products, including detailed descriptions, technical data, user manuals, test reports and downloadable CAD drawings

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