1. Field of the Invention
The present invention relates to electronic connectors. More particularly, the present invention relates to electronic connectors for connecting circuit boards.
2. Description of the Related Art
A variety of circuit boards and circuit board connectors are used in computer systems. The main circuit board (“main board”) of a computer system such as a PC or server is typically referred to as a motherboard, having a plurality of electronic components connected by electrical communication pathways. Motherboard components include processors, drive controllers, video controllers, primary memory, interrupt controllers, and BIOS, as well as electronic connectors for interfacing with additional components. Electronic connectors are typically included with a main board for connecting additional circuit boards, such as a “daughter card,” to provide electronic communication (i.e. the transfer of power and signal information) between the motherboard and the circuit boards to be connected. The terms “daughter card” and “daughter board” are routinely interchangeably used to refer to an extension or “daughter” of a motherboard or other main board. A daughter board may include plugs, sockets, pins, or connectors for attaching still other boards to the daughter card.
The term “mezzanine card” is often used to describe a daughter card mounted closely in parallel to a main board to expand the functionality of the main board. This closely-spaced, parallel arrangement helps achieve a compact form factor, which is particularly desirable in applications such as blade servers to minimize blade size and maximize blade density. The connector used to connect a mezzanine board to another circuit board may be referred to as a mezzanine connector. One practical application of a mezzanine board is to expand upon the functionality of the main board to which it attaches, without requiring a redesign of that main board or a redesign of the way in which the main board may attach to another circuit board. For example, a piece of hardware may be upgraded periodically by creating a new mezzanine card having additional or modified functionality, without necessitating a redesign of the main board, itself. One illustration of this mezzanine-type arrangement of circuit boards is the attachment of a MIDI daughter board parallel to a sound card, wherein the sound card itself is attached to a PC motherboard either in a mezzanine arrangement or at a selected angle with respect to the motherboard. The MIDI daughter board may be used to expand the functionality of the sound card without requiring a redesign of the main sound card or the way it attaches to the motherboard.
As electronic packaging becomes increasingly dense, the number and density of high-speed electronic connectors increases. Consequently, the mechanical integrity of circuit boards and supporting infrastructure is limited, such as in the case of thin blade servers. Such circuit boards and infrastructure may be prone to failure due to the relatively high mating forces between components, such as between two circuit boards. Conventional electronic connectors typically include two connector members each having an array of mating terminals or pins that are frictionally joined with one another as a result of mechanically coupling the two connector members. Thus, the forces required to mechanically couple the two connector members includes the force required to frictionally join a large number of mating terminals. Connecting the two connector members typically requires pressing one connector member into engagement with the other connector member, which applies a similar force to the two boards being connected, as well as to any supporting structure for the two boards. These forces and relative movement can damage the circuit boards or supporting structures. Furthermore, the individual pins on one connector are prone to damage if misaligned with the mating pins on the opposing connector prior to joining the circuit boards.
Therefore, improved connectors for electronic circuit boards are needed. One area for improvement would be to reduce the force required to connect two circuit boards. It would be desirable to provide a connector that can connect two circuit boards with zero insertion forces in order to avoid stress on the circuit boards. It would also be desirable to increase the reliability and durability of connectors so they are less prone to being damaged with use. Still further, it would be desirable if such a connector provided for the passage of cooling air flow so that it could be positioned anywhere on the circuit boards without adverse thermal affects.