Electrical connector for printed circuit cards

Jan. 29, 1963 _F raddin

ELECTRICAL CONNECTOR FOR PRINTED

3,076,166

CIRCUIT CARDS

Original Filed Dec. 13, 1956

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FIG. 2

INVENTOR.

franklin rad din

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attorney

United States Patent Office 3,076,166 , Patented Jan. 29, 1963

3,076,166

ELECTRICAL CONNECTOR FOR PRINTED _ ' CIRCUIT CARDS

Franklin Raddin, Morristown, N.J., assignor to Monroe Calculating Machine Company, Orange, N.J., a corporation of Delaware

Original application Dec. 13,1956, Ser. No. 628,034, now Patent No. 2,956,258, dated Oct. 11, 1960. Divided and this application Sept. 30, 1960, Ser. No. 59,668

Claims. (Cl. 339—17)

This invention, which is a division of copending patent ^“P⁸^⁴- ^filed December 13, 1956, now Patent 2,956,258, dated October 11, I960, by Franklin Raddin, relates to electrical connectors for printed circuit cards or the like.

It is well known that printed. circuit cards provide a number of advantages when used in electronic apparatus, such cards are especially suited to mass production and make possible a reduction in the size of electronic apparatus. They also provide a modular type of construction m electronic equipments that simplifies the maintenance problem by permitting a quick substitution of small units which become defective.

To provide for easy replacement, the printed circuit cards normally include multi-contact plugs which enter into sockets in a chassis or inter-connection unit. The making of soldered connections to the ends of the plug adds to the cost of construction and such plugs have a number of disadvantages as a means for making connections to printed circuit cards, especially when the cards are miniaturized. .

The plugs require an appreciable mechanical force on each pm to insure a reliable contact resistant to corrosion vibration, and shock. As many contacts are normally required, the force necessary for insertion and removal of a card is considerable. Equipments using printed circuit cards are normally compact so that it is frequently difficult to apply an appreciable force to remove and insert the cards.

In any event, the plugs limit the degree of miniaturiza- .. tion which can be obtained. The card must be large “ enough to withstand the forces applied to it for insertion and removal. The pin size and spacing necessary for the plug is another limiting factor on the size of the card.

The apparatus of the instant invention provides a means for making reliable connections directly to the printed terminals along the edges of printed circuit cards. The spacing of the printed terminals may be the same as the spacing of other printed conductors. Substantially zero force is required to insert and remove the cards so that they need to be only strong enough to support the printed circuitry and other circuit components.

In the apparatus of the instant invention, a fluid pressure is applied uniformly along rows of mating contacts to hold them together with sufficient force to insure connections resistant to corrosion, vibration, and shock. At least one of the. cards or other member supporting sets of contacts is flexible and the fluid pressure means is conformable in shape so that a substantially uniform pressure will be applied to each pair of mating contacts despite small dimensional variations in the contacts or their supporting members. The fluid pressure is removed to allow insertion and removal without wear and undesirable mechanical stress.

An object of the invention is an improved means of making connections to printed circuit cards.

A_ further object of the invention is apparatus for making connections directly to printed terminals on printed circuit cards wherein a uniform contact pressure is maintained with each terminal.

A still further object of this invention is apparatus for ' ’ ²making connections to printed circuit cards from which the cards may be inserted and removed with the application of substantially zero force.

Other objects and advantages together with a fuller understanding of the invention, will be had by referring to the following description and claims taken in conjunction with the accompanying drawings in which: . FIG. 1 is a perspective view of one embodiment of the invention having a section cut away to show the internal structure.

FIG. 2 is an elevation view of a vertical section of the embodiment of FIG. 1 taken along the line a—a.

.Notched member .11 joins to bar 12 by screws (not shown) or by any other suitable means, so that the two form a vertical slot running longitudinally. Printed circuit card 13α is inserted in the slot from the upper side and printed circuit card 13b from the lower side so that portions thereof overlap each other in the slot. Member 11 is made of a rigid material and has a chamber hol™^WiL^{OUt with an} opening along the side of the slot.' Fluid filled flexible bag 14 is mounted inside the chamber with a_ side adjacent to the slot. Screw 15 journeys through a threaded hole in one end of member 11 and extends inside the chamber. Plate 16 rotatably joins to the end of screw 15 inside the chamber.

When screw 15 is turned inwardly, it forces plate 16 against fluid filled bag 14. The fluid inside bag 14 is substantially incompressible so that the longitudinal compression causes the bag 14 to expand laterally into the side of the slot and to press cards 13a and 13b together against bar 12. Bag 14 is flexible so that it conforms to the shape of printed circuit card 13b .allowing pressure to be applied uniformly along the portion adjacent to the chamber opening. As the area of plate 16 is smaller than that of the portions of cards 13α and 13b in the slot, the force exerted on the cards 13α and 13b is considerably greater than on plate 16. Screw 15 provides a further mechanical advantage for manual adjustment

Printed circuit cards 13α and 13b each have a plurality of printed conductors 17 extending along the overlapping sections of their adjoining sides. Printed conductors 17 bn cards 13α and 13b are in mating relation so that each conductor 17 on card 13a makes contact with a corresponding conductor 17 on card 13b when cards 13a and 13b are pressed together. Cards 13α and 13b are sufficiently flexible to bend under the pressure exerted through bag 14.

This flexibility of cards 13a and 13b makes it possible to hold each mating pair of conductors 17 together with ₅₀ substantially the same pressure despite small dimensional irregularities in thickness. Since no close tolerances are required, cards 13α and 13b may be manufactured by low cost methods. Cards 13α and 13b may be of any suitable type and have any arrangement of printed cir55 cuitry and other components.

It will further be recognized that various other arrangements could also be used for obtaining fluid pressure in the invention other than that shown. For example, a cam type mechanism positioned by a lever could be used ₆₀ instead of a screw to move a plate against the bag. Such a mechanism would permit quick application and removal oi pressure but would require an additional adjusting means to obtain the desired pressure in the event of changes in dimensions of the chamber in which the bag is located or of the cards and connectors used.

While the invention has been described with a certain degree of particularity, it is understood that the present disclosure has been made only by way of example, and that numerous changes in the details of construction wherein a combination and arrangement of parts may be resorted to without departing from the spirit and scope of the invention as hereinafter claimed.

3,076,166