In automotive instrument panels individual display or controller components, for example for heater and air conditioner control, are packaged separately from other such components. This allows circuits board dedicated to the function of that component and other circuit elements and their interconnections to be assembled into a protective environment and tested before installation into the instrument panel. Each such component may have manually controlled input knobs or push buttons mounted on a housing having a front panel for use by the vehicle operator, so that wiring or cables are necessary for coupling such front panel devices to the circuit board or other control circuitry within the enclosure. The housing in some cases includes an additional printed circuit board or keyboard mounted on the rear face of the housing parallel to the front panel.
Heretofore it has been known to use a one-piece rigid case having an open end which is married to the housing and secured by a number of screws. A track within the case is provided to slidably accept a circuit board, and a long interconnect cable coupling the housing to the circuit board is stuffed into the case during assembly to the housing. Such an assembly results in loose circuit boards which do not fit securely in the case and additional screws are needed to secure the circuit board. Assembly problems due to so many screws and the long cable are evident, and the cable routing cannot be controlled.
Additional prior structures include a two-piece sheet metal or molded plastic case which allows closure of a cover after the circuit board is installed and the cable is arranged. Such a molded case may have the two case pieces joined at a living hinge to operate in a clamshell fashion. In any event, these enclosure schemes still require a number of screws to hold the circuit board in position and to assemble the case to the housing. In addition, where a key board is used, additional fasteners are used to secure it to the housing. Forming the necessary screw holes in the mounting flanges of a molded case requires expensive molding equipment.