Plug connector for a printed circuit board

[57] ABSTRACT

An electrical plug connector for a printed circuit board which has electric circuits and edge connection pads on both sides of the board includes an insulating moulding 10 having a spine portion 11 and a conjoining plug portion 12, and electrical contact fingers 21 which are secured in through-holes 14 in the spine portion, have hooked plug ends 25 which engage in slots 18, 19 formed in the free end of the plug portion, lie in shallow slots 17 on the plug portion, and have at the other side of the spine portion free ends 30 set to resiliently engage with and be soldered to edge connection pads on a printed circuit board. The spine portion has end extensions which carry clamping bands 13 for enabling the connector to be firmly secured to the edge portion of a printed circuit board. The plug part of the moulding and the associated hooked plug ends of the contact fingers 21 are intended to simulate the edge of a two-sided printed circuit board to which the connector is to be connected, so that a conventional socket connector can be used therewith.

Claims, 7 Drawing Figures

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?ΛΤΕίί·'Ρυϋΐΐ51975 3.894.784

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PLUG CONNECTOR FOR A PRINTED CIRCUIT BOARD

This invention relates to an electrical plug connector for a printed circuit board.

Some present day printed circuit boards are of considerable size, and hence of considerable value. Circuits carried on such a board make connection with external circuitry by means of plug and socket connection means. Some printed circuit boards have circuits which end adjacent an edge of the board in connection pads with which external circuit connection is made by means of socket devices which mate directly with the edge of the board, and which have resilient contacts which make contact with the aforesaid connection pads. These connection pads can be damaged by repeated application and removal of such socket devices, so that ultimately a board can no longer be used simply because of the inability to make good electrical connection with the damaged connection pads.

According to the present invention an electrical plug connector for a printed circuit board which has electric circuits and associated edge connection pads on both sides of the board comprises an electrical insulating moulding having a spine portion for disposition adjacent an edge of such a printed circuit board, and a plug portion extending from the spine portion on one side thereof for disposition remotely from such an edge of a printed circuit board, and ha' ng a transverse thickness substantially equal to that of the edge of the printed circuit board, the spine portion having a greater transverse thickness than the plug portion, and two transversely spaced rows of through-holes, which rows of holes open adjacent the plug portion on opposite sides respectively of the plug portion, the holes in each row being spaced apart along the length of the moulding, and the plug portion having at its free end two transversely spaced rows of slots, the slots in each row being positioned along the length of the moulding in alignment with the respective through-holes which open on the same side of the plug portion, and a plurality of resilient strip, electrical contact fingers each comprising a median fastening part, a hooked plug end part extending from the median part at one end thereof, and a printed circuit board contacting free end part extending from the median part at the opposite end thereof, each contact finger having its median part extending through and fixed in one of the said through-holes in the moulding, its hooked plug end part engaged in an associated one of the said slots at the free end of the plug portion of the moulding, and its free end part extending from the spine portion of the moulding whereby to make elecrical connection with an edge connection pad of a printed circuit board when the connector is presented to an .edge part thereof, the said plug portion of the moulding and the contact fingers together simulating the edge of such a printed circuit board.

Preferably, the plug portion has a plurality of parallel shallow grooves in each of its longitudinal faces, and the plug end parts of the contact fingers lie in those grooves; and the plug portion of the moulding has a longitudinal rib at its free end, which rib lies between the two rows of slots and projects beyond the extremities of the hooked plug end parts of the contact fingers.

According to another preferred feature of the present invention the spine portion of the moulding has first abutment means formed in outer parts thereof which define the respective outer boundaries of the respective through-holes, and each contact finger is shaped so that its median part bears resiliently against the said outer part of the through-hole in which it is located and has second abutment means thereon arranged to engage with the aforesaid first abutment means in the throughhole whereby to locate and secure the contact finger in that hole.

Preferably, each through-hole in the spine portion of the moulding has a T-shaped transverse cross section having a broad part in which is carried the associated strip contact finger, and a narrow part extending inwardly from the broad part towards a central part of the spine portion; and each slot in the free end of the plug portion of the moulding extends from the said free end towards the spine portion, and has a T-shaped transverse cross-section having a broad part in which the hooked plug end of the associated contact finger is inserted, and a narrow part extending outwardly from the broad part towards the contact finger.

The spine portion may have longitudinal end extensions which extend beyond the ends of the plug portion, and clamping means carried on each said end extension which enable the connector to be secured in positon on an edge part of a printed circuit board after positioning thereon with the said free end parts of the contact fingers resting in electrical contact with adjacent edge connection pads formed on the board.

One edge connector according to the present invention for a printed circuit board having electric circuits and edge connection pads on both sides thereof will now be described by way of example and with reference to the accompanying drawings, drawn to an enlarged scale, in which:

FIG. 1 shows a front view of the connector;

FIG. 2 shows a plan view of the connector;

FIG. 3 shows a vertical section taken on the line III—III of FIG. 1;

FIGS. 4, 5 and 6 show respectively front, plan and underside views of a moulding incorporated in the connector; and

FIG. 7 shows a vertical section taken on the line VII—VII of FIG. 4.

Referring now to the drawings, the connector comprises an electrically-insulating moulding 10 of a thermoplastic moulding material, such as polycarbonate material, and having a spine portion 11 and a conjoining plug portion 12. Lengthwise the spine portion extends beyond the plug portion and carries at its ends clamping bands 13 for securing the connector firmly to an edge part of a printed circuit board, as will be explained later.

Whereas the plug portion has a transverse thickness which corresponds to the thickness of a printed circuit board to which the connector is to be secured, the spine portion has a greater thickness and projects on both sides of the plug portion. The spine portion has formed therein two longitudinally-extending rows of spaced parallel holes 14 of T-shaped cross-section,

3,894,784 which holes open on to the respective longitudinal faces 15, 16 of the plug portion.

From these holes shallow parallel grooves 17 extend along the respective longitudinal faces 15, 16 of the plug portion, and terminate at the free end of the plug 5 portion in slots 18, 19 which extend towards the spine portion and have T-shaped cross-sections. A nose rib 20 extends along the length of the plug portion and separates the slots 18, 19 from one another.

Carried within the holes 14 in the spine portion 11 10 are phosphor bronze contact fingers 21 which are located in those holes by anti-withdrawal and location projections 22 and 23 respectively, which projections engage in appropriately shaped recesses formed in the outer wall parts 24 of the spine portion. 15

Each contact finger has a hooked end part 25 which engages in, and is secured against movement by, one of the T-shaped slots 18, 19 at the free end of the plug portion. Sets in each contact finger at 26, 27 cause the part of the contact finger lying adjacent the plug por- 20 tion of the moulding to lie snugly in the appropriate shallow groove 17, and the median part of the finger to lie adjacent the outer wall part 24 of the spine portion.

Two further sets at 28, 29 in the parts of the contact fingers which protrude from the free end of the spine ²⁵portion cause those parts of each pair of contact fingers to converge and to have divergent tip parts 30. The spacing of the tip parts from one another is such as to cause them to apply a positive pressure to the appropriate connection pads on the printed circuit board when ³the connector is secured thereon.

The connector is assembled simply by inserting the contact fingers 21 in the holes 14 of the spine portion, and guiding them so that their hooked ends 25 enter the appropriate slots 18, 19 on the respective sides of the nose rib 20. Each contact finger is finally positioned when the anti-withdrawal and location projections 22, 23 engage in their respective recesses.

The sets are then made in the contact fingers at 28 and 29, and the connection is completed by securing around the ends of the spine portions the clamping bands 13.

To affix the connector to a printed circuit board the connector is placed with the divergent tip parts of the contact fingers adjacent the edge of the printed circuit board, and pressure is applied to ease the contact finger tip parts and the clamping bands on to the respective surfaces of the board. The connector is secured by bolts passed through holes in the clamping bands and circuit board, and nuts tightened on the bolts.

The electrical connection of the contact finger tip parts and the connection pads of the printed circuit board is completed by a soldering process.

The plug connector is thereafter ready for use, and has the merit that it can cooperate with socket connectors which have hitherto been used to mate directly with the edge of the printed circuit board. Furthermore, the plug connector has the merit that it lies in the same general plane as the printed circuit board, and demands no greater separation of adjacent printed circuit boards than that is required by other pertinent considerations.