PRODUCT OF THE WEEK: nVent Schroff’s Positive Retraction Card-Lok for rugged environments
Sponsored StoryJanuary 27, 2025

This week’s product, the nVent Schroff Positive Retraction Card-Lok, is designed for use in rugged military environments when a printed circuit board (PCB) must be reliably removed from a chassis in the field. The solution eliminates stiction -- the force required to move an object that is at rest, or the resistance to starting motion -- while also providing improved clamp force and better thermal dispensation than standard card-loks.
The positive retraction mechanism enables the Positive Retraction Card-Lok to disengage from the wall of the chassis by eliminating the stiction. The nVent Schroff solution is then able to retract, and the PCB can be removed from the chassis, enabling access to vital electronics.
Advantages Over Standard Card-Loks
Card-loks are important to secure ruggedized VPX systems, but standard card-loks can become stuck in the chassis. nVent Schroff’s positive retraction card-lok design avoids stiction failures enabling guaranteed removal in 2nd level, at the same time improving the clamping force and heat dissipation of standard card-loks.
Customizable
Positive Retraction Card-Lok can be a leveraged as a standard commercial off-the-shelf (COTS) product or modified to meet application requirements. The solution is also optimized for size, weight, and power (SWaP) requirements.
These versions are drop-in replacements of the nVent Schroff 260, 265, and 280 Calmark and Birtcher lines.
Clamp force/thermal management
- Meets advance requirements for heat dissipation and shock and vibration resistance
- Positive retraction for gold chem showed clamp force at 450 lbs, 2.4 times higher than standard card-lok
- Thermal resistance for gold chem was measured at 1.22 ℃/W, 45% lower than standard card-lok
Key Features
- Recommended gap width: PCB + 7.62 mm (.300 in)
- Recommended torque: 68 N-cm (6 in-lbs) with “L” option 90 N-cm (8 in-lbs) and the weight: .95 g/cm (.085 oz/in)
- Materials
- Bodies and wedges: Material: Aluminum alloy 6061-T6 per ASTM-B221 or AMS-QQ-A-200/8
- Shaft: Material: Aluminum alloy 7075-T6 per ASTMB221 or AMS-QQ-A-200/11
- Screw (.09-in. or 2.5-mm hex. socket head cap screw, depending on mounting configuration): Material: 300 Series Stainless Steel per ASTM-A582
- Back and front roll pins: Material: 400 series stainless steel
- Shim: Material: 300 Series Stainless Steel per QQ-S-766
For more information, visit the Positive Retraction Card-Lok product page here, or visit the company’s website, or follow the links below.
Resources:
- To view the Positive Retraction Card-Lok data sheet, click here.
- To read a whitepaper on positive retraction card-lok technology, click here.
- To watch a video the Positive Retraction Card-Lok, click here.
- For sales information, click here.