Back chassis

The back chassis is a large, shallow tray of thin steel that forms the backbone of an LCD TV. Everything in the backlight unit sits in or on it: the LED strips, the reflector sheet, the diffuser plate and the optical films. The LCD panel is held in front of it.

It starts as a coil of galvanized steel, typically around a millimeter thick or less. The coil is unrolled, flattened and fed into a stamping press. Hardened steel dies press the sheet into shape in one or more strokes: the flat floor, the raised edges, stiffening ribs, and holes and tabs for screws and brackets. Because the steel is already zinc-coated, the cut edges and bends don't need painting; the zinc around them protects them.

The tray does several jobs at once. Its ribs and edges keep a very wide, thin product from twisting. It spreads heat away from the LEDs. It acts as an electrical ground and helps block electrical noise. The circuit boards, speakers and stand are often screwed to it too. Steel is used because it's stiff, cheap and easy to press; some thin, premium TVs use aluminum instead.