The primary purpose of a heat frame is to reinforce the PCB and make it stiffer for improved resistance to shock and vibration, but the heat frame also provides a direct thermal path for PCB components via the frame, cross bars and backing plates or thermal strips. A heat frame typically consists of the machined aluminum cooling frame with cross bars. The cross bars, or stiffening ribs, that run across the board are usually board specific and depending on the placement of the electrical components on the board. The combination of the cooling frame, cross bars, and wedge locks conduct heat away from components on the PCB to the chassis and surrounding environment. Accordingly, higher mass board components, as well as high power and heat dissipation parts, are typically placed in close proximity to the card edges or stiffening ribs since this is the optimal location for thermal transfer and mechanical support. A backing plate can be added which acts as a heat spreader for board components. The underside of the plate can be machined to match the component heights and locations on the board. The use of the cross bars along with a cooling plate, improve the structural rigidity of the board making the connector pins and housing less susceptible to damage, allowing the board to meet shock and vibration requirements for rugged applications. If a backing plate is not used, then backing thermal strips are used to provide the appropriate spacing to go into the chassis cold-wall channel.