US2802995A - Printed circuit connection and method of making same - Google Patents

Description

1957 F. F. MAUTONE EI'AL 802,995

PRINTED CIRCUIT CONNECTION-AND METHOD-OF MAKING SAME Filed July 11, 1952 and United States Patent PRINTED CIRCUIT coNNncrioN ANn Merino!) or MAKING SAME Francesco F. Mautone and Clitford'F. Hoffman, Chicago, Ill., assignors to Admiral Corporation, Chicago, lit, a corporationof Delaware Application July 11, 1952, Serial No. 298,242

Claims. (Cl. 339-17) Although use of vacuum tubes in printed circuits is not new, their use required specially constructed sockets which were more expensive than are sockets of. the class employed in wired circuits. Also, the terminal lugs of the special sockets are longer than the corresponding lugs on standard sockets and are folded backward over themselves so that the problem of inductive and/or capacitative losses is involved, especially where the specials'ockets are employed in circuits for conducting currents at ultra high frequencies.

The foregoing disadvantages are overcome by the present invention due to which it is now possible to employ a standard socket; that is, a socket of the class used for wired circuits.

In keeping with the thought of the invention, special shaped apertures are made at appropriate points in the dielectric material on which conductors of a printed circuit are disposed. The terminal lugs from standard sockets are inserted through the apertures and concurrently, the several terminal lugs of each of the sockets are bent laterally thereof, and each folded on itself intimately in association with one of the printed conductors. Then the dielectric, on which the foregoing elements are carried, is turned downward into engagement with the surface of a bath of molten solder, removed from the solder and cooled.

A better understanding of the invention and one means by which it may be practised is illustrated in the drawing in which:

Fig. l is a fragmentary perspective view of a. support plate of dielectric material uponwhich printed conductors are provided;

Fig. 2 is a fragmentary bottom plan view of the support plate showing one conformation that a printed circuit may take;

Fig. 3 is a side elevational view of a conventional tube socket, drawn to an enlarged scale;

Fig. 4 is also an elevational view of the socket, after it has been temporarily attached to the support plate;

Fig. 5 is a fragmentary sectional view showing the means for treating the plate-supported socket and means for bonding the printed conductors and terminal lugs together; and

Fig. 6 is an additional elevational view showing the plate and socket after their connection with each other has been improved by the bonding agent.

The reference character 11 is used, throughout the drawing, to denote a support member taking the form of a plate of some suitable dielectric material such as Bakelite. Not only does the plate provide support on its Z,8@Z,%5 Patented Aug. 13, 1957 ice upper side for vacuum tube sockets 12, in a manner later to be described, but it also carries a series of irregular-shaped conductors 13 printed on its lower side by some suitable process.

Each of the sockets 12 engages the plate 11 over an aperture 14 therein. Each of the sockets, on the other hand, has a cluster of terminal lugs 16 extending down ward from its base in spaced circular relation about a shielding pin 17, at the axis of said base. As can best be understood from Fig. 1, the lugs, each of which forms a socket disposed in the top. openings in the base for the reception of the tube pins, are usually equally spaced about the circle except at one point where there is no lug, which assures that the tube can only be placed in the socket in the proper manner and also serves as a means for identifying the purpose of the pins and/or lugs. The lugs 16 are collectively received within the aperture 14 and being intimately associated with the peripheral walls of said aperture, serve to resist displacement of the socket toward the edges of the support plate. This condition is additionally improved as follows: The

lugs 16 are of length greater than the thickness of the as follows:

plate 11;' hence they are long enough to extend beyond the lower surface of the plate. Advantage is therefore taken ofthe excess length of. lugs to provide connector portions or tangs 18 (Fig. 4), by bending the respective lugs at the edge of aperture 14 and lower surface of plate 11 so that they extend in a direction radially of the axis of the socket. By so extending, a larger area of each of the tangs is in more intimate association with the conductors 13, for a reason later to be indicated, and

also because the tangs resist removal of the sockets in a direction axially thereof from the apertures during assenibling of other sockets or components on the plate 11. At the same time that the projecting lugs are thus bent, in one direction, at the edge of the apertures, said lugs are also bent transversely thereof intermediate their free ends and support plate, in the opposite direction for the tangs to be folded on themselves as indicated in Fig. 4. The reason for adding the second fold to the tangs is The lugs 16 are of metal having a slight resilient quality. Consequently, it is impossible to bend the lugs substantially more than 90 degrees around the edge of the apertures 14, and therefore not far enough to provide tangs parallel to the plate 11, when pressure, for forming the bends at the edges of the apertures, is removed. Accordingly, it was ascertained, experimentally, that incorporating a second fold as indicated (Fig. 4) served to obviate a slant in the tangs from the apertures.

The tangs 18 are formed preferably by means of a power press equipped with suitable dies. By such apparatus it is proposed to form all the tangs on a socket simultaneously and similarly form the tangs on the re maining" sockets, although the use of dies suitable to simultaneously form all the tangs on the total number of sockets, attached to a plate of insulating material, is also contemplated.

The sockets 12 are tied against rotation about their axes, and the tangs 18 consequently are restrained against edgewise displacement or disengagement from the conductors 13 by a lug 2t). Said lug extends inward from the edge of the aperture 14 between the two lugs having the greater space to the pin 17.

A fragment of a die, which may take various forms is shown in Fig. 4. It includes a center sleeve 50 and an outer sleeve 51. The center sleeve is provided with an opening 52 which enables it to telescope around the member 17 and the outer sleeve is movable relative to the of the plate is brought into communication with the surface of a bath of molten solder 19 contained in a receptacle 21. Owing to its buoyancy the solder may support the plate 11 while the tangs 18 and pin 17 dipping below the surface of the solder draw the same thereover by capillary attraction and assist its bridging the gaps between the conductor members 13, tangs 18 and pin so that when the plate 11 and parts supported thereby are removed from the solder and allowed to cool excellent soldered joints are the result.

The duration of contact with the solder of plate 11 and plate-supported elements alluded to is variable in accordance with the composition of the plate and socket, besides the temperature to which the solder is heated. The temperature should not be so high for such a period as to cause blistering of the dielectric or loosening of the conductors therefrom or for the plate to disintegrate or become Warped. On the other hand, the duration should, of course, be for a period long enough for heat of the solder to overcome surface tension in minute crevices so that good contacts between the parts is assured. Generally speaking, the duration of the soldering operation should be for from two to six seconds when the temperature of the solder is from 475 degrees to 550 degrees Fahrenheit. In the course of several tests, good soldered joints were produced when the solder was heated to 515 degrees F. and the plate thus subjected to the solder for three or four seconds.

Once the plate 11, socket, etc. have been removed from the solder, said solder bonds the parts together and by its surface tension assures a thickening tendency to the conductors as well as accumulating in crevices to provide fillets thereby improving the conductive qualities of the circuit.

While we have shown our invention in an embodiment thereof, we are aware that extensive other departures may be made therefrom without departing from the spirit or scope of the invention.

We claim:

1. The method of producing electrical connections between a plurality of conductors printed on a plate of dielectric material and at least one group of terminal lugs extending through the plate initially perpendicular to and beyond the surface on which the conductors are disposed, each of the conductors being associated with at least one of the lugs, consisting of the steps of subjecting groups of the lugs to the force of dies by which said respective lugs are concurrently bent laterally thereof over the conductors, and then floating the plate conductor-side down on the surface of a bath of fused solder only long enough to concurrently bond the lugs to the conductors.

2. The method of producing electrical connections between a plurality of conductors printed on a plate of dielectric material and at least one group of terminal lugs extending through the plate initially perpendicular to and beyond the surface on which the conductors are disposed, each of the conductors being associated with at least one of the lugs, consisting of the steps of subjecting groups of the lugs to the force of dies by which said respective lugs are concurrently bent laterally thereof so that they extend radially outward and at the same time bent intermediae their first mentioned bends and their free ends so that from their second bends they extend i11- ward and folded on themselves thereby providing tangs, and then floating the plate conductor-side down on the surface of a bath of molten solder only long enough to simultaneously bond all the lugs to the conductors.

3. The process of simultaneously providing an electrical connection between at least one conductor printed on a plate of dielectric material and at least one of a cluster of lugs of a tube socket extending through the plate and being bent at the conductor side thereof for extension laterally over the conductor and, comprising the step of floating the plate with the conductor side down on the surface of a bath of molten solder long enough for communication of the solder to the lugs and conductors to provide a bonded relationship between said conductors and said lugs.

4. Electronic apparatus comprising a support plate of dielectric material carrying on one side thereof a plurality of tube sockets and a plurality of conductors printed on the other side, the plate having apertures therein and each of the sockets having a plurality of lugs extending through one of the apertures, tang portions formed from the lug portions in extension beyond the apertures each of the tangs being bent and extending laterally of the lugs of the respective sockets and folded on themselves and in intimate association with the conductors, and solder between the conductors and tangs and bonded to said conductors and tangs.

5. An apparatus of the class described comprising an insulating base having a printed circuit on one side, said base being formed with an aperture in predetermined alignment with elements of the printed circuit, a socket for the reception of a vacuum tube or the like having pin receiving openings and connectors in the openings having solder lugs extending from the connectors beyond the socket in spaced relation in a circle about the axis, said lugs being equally spaced about the circle and provided with a gap between at least two of the lugs, said aperture in said base having a tongue arranged to extend between said two spaced lugs when the socket is disposed on the base to hold the socket in predetermined alignment with respect to said printed circuit elements and said lugs being bent downward and outward and back upon themselves to provide a secure connection of the lugs with the circuit elements and solder means completing the electrical connection between the lugs and circuit elements.

Del Camp Apr. 29, 1952 Del Camp Oct. 7, 1952

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