1. Field of the Invention
This invention relates to an electrical connector for establishing an electrical connection between a printed circuit board and a plurality of wires and more particularly relates to a connector having a plurality of terminals each suitable for forming a compliant electrical contact with conductive paths located on one side of a printed circuit board.
2. Description of the Prior Art
A number of conventional electrical connectors have been used to establish contact with conductive paths located along one or both sides of a printed circuit board adjacent the edge of the printed circuit board. Electrical connectors suitable for establishing electrical contact with terminals along one side of a printed circuit board fall into generally two categories. Some electrical connectors, such as that shown in U.S. Pat. No. 3,075,167 employ edge stamped contact terminals suitable for establishing electrical contact with conductive pads along the stamped edge of the terminal. Other connectors employ a more compliant configuration in which terminals are stamped and formed in such a manner that a leaf spring having a flat surface establishes the electrical contact with the conductive pads on the printed circuit board. These leaf spring type contacts are more compliant than the edge stamped configurations. One electrical connector employing a leaf type contact is the Bifurcated Leaf connector manufactured and sold by AMP Incorporated.
U.S. Pat. No. 3,075,167 discloses a printed circuit board electrical connector having flag type terminals. These flag type terminals are edge stamped terminals. Contact with the printed circuit board is established by a pair of parallel contact arms which have contact surfaces adjacent their ends. These contact arms are part of the same metal stamping, and each arm is joined to a web portion at its base. The terminals are positioned with opposed arms on opposite sides of board receiving slot and the printed circuit board is inserted between the opposed arms. Since these opposed arms comprise edge stamped members, they are relatively rigid and not very compliant. Thus, these terminals have a limited deflection range. One problem which can be encountered with this type of connector is that one or both arms can be overstressed by a printed circuit board that is either the wrong size or is inserted improperly into the connector. For example, the printed circuit board can be inserted on an angle thus overstressing one or both of the contact arms. A printed circuit board can also be inserted into a connector of this type and the contact pads will not properly engage one of the contact points adjacent to contact pads. For example, the board may be warped, thus reducing the normal force with specified contact terminals. Other problems which may be encountered with a connector of this type is that the thickness of the printed circuit boards may not be properly controlled, again, causing potential problems.
It should be understood, however, that electrical connectors of this type have been reliably used. Reliable use of connectors of this type is, however, dependent upon a close monitoring of the connector board interface. One additional problem that results with connectors of this type is that the contact force between the terminals and the conductive pads may vary over the life of the connection. This is in part due to the fact that a precise positioning of the board relative to the terminals cannot be assured, and because the terminals themselves are not relatively compliant.
U.S. Pat. No. 3,787,801 discloses another connector for establishing a contact with a printed circuit board. This connector also employes flag type terminals. Those terminals are formed upwardly from an intervening web, and embossed contact surfaces are formed adjacent the end of the opposed arms. In this connector, the opposed arms are substantially identical. As such, the contact force applied by each contact arm is substantially identical for a given deflection. However, the deflection of the contact arm is again dependent upon the structure and configuration of the printed circuit board. Since the contact force between the terminal and the conductive pad on the printed circuit board is dependent upon the deflection of the contact terminal, it is difficult to insure the precise contact force which will be maintained, especially over the life of the terminal.
U.S. Pat. No. 3,720,907 discloses another printed circuit board electrical connector having two relatively compliant opposed arms extending upwardly from an intervening web. Note that the contact force generated by the opposed arms for this relatively compliant terminal is also dependent upon the precise positioning of the printed circuit board, in much the same manner as with the connector shown in U.S. Pat. No. 3,787,801.
The electrical connectors depicted in the preferred embodiment of the invention disclosed herein provide a means for establishing a compliant electrical contact with conductive pads on a printed circuit board, while at the same time, establishing a relatively assured deflection of the compliant spring comprising a part of the terminal using the connector. This connector employs a relatively rigid support arm opposed to a relatively compliant contact spring. The relatively rigid support arm engages one side of the printed circuit board to precisely position the printed circuit board relative to the deflectable contact spring. Virtually all the deflection which occurs in the terminal is limited to the deflection of the single contact spring, thus establishing a well defined contact force which is not only present at the time of initial termination but, which can be maintained and defined within prescribed limits over the life of the interconnection.