US 3711819 A
A family of electrical connectors for mating with a plurality of closely spaced, parallel square pins comprises an insulating housing and a plurality of female contacts mounted in said housing. Each contact is folded from sheet metal into a channel having a general U cross-section, when viewed from the direction of mating, has twin spring fingers struck from the respective sides of said channel for engaging opposite sides of a square pin when same is inserted into said contact, and has a folded back plate for reinforcement and limiting depth of contact entry. Generally, each contact is retained in its insulator by either (a) notches thereon which snap over respective bosses in the insulator cavity during contact insertion, or (b) extension portions which overlie the front and rear of the insulator housing after contact insertion.
Description (OCR text may contain errors)
Umted States Patent I 1 [111 3,711,819 Matthews 51 Jan. 16, 1973 54] SQUARE PIN RECEPTACLES 266,177 7/1964 Netherlands ..339/l7 C EMPLOYING CHANNEL CONTACTS Primary Examiner--Robert L. Wolfe  inventor: Russell H. Matthews, South Assistant Examiner Lawrence Swab Pasadena Cahf' Attorney-D. R. Pressman  Assignee: Elco Corporation, Willow Grove,
. p  ABSTRACT  i Feb 8,1972 A family of electrical connectors for mating with a App]. No.: 224,549
US. Cl. .339/192 R, 339/2l7 S, 339/220 R, 339/258 R Int. Cl. ..H01r 13/12, HOlr 23/02 Field of Search ..339ll7 C, 17 LC, 192, 256, 339/258, 262, 217 S, 176 M FOREIGN PATENTS OR APPLICATIONS 6/1964 Great Britain ..339/25.8 R
plurality of closely spaced, parallel square pins comprises an insulating housing and a plurality of female contacts mounted in said housing. Each contact is folded from sheet metal into a channel having a general U cross-section, when viewed from the direction of mating, has twin spring fingers struck from the respective sides of said channel for engaging opposite sides of a square pin when same is inserted into said contact, and has a folded back plate for reinforcement and limiting depth of contact entry. Generally, each contact is retained in its insulator by either (a) notches thereon which snap over respective bosses in the insulator cavity during contact insertion, or (b) extension portions which overlie the front and rear of the insulator housing after contact insertion.
10 Claims, 9 Drawing Figures PATENTEDJAN Is 1975 SHEET 1 [IF 3 PATENTEDJANISIHB 3.711 819 SHEET 3 or 3 SQUARE PIN RECEPTACLES EMPLOYING CHANNEL CONTACTS BACKGROUND: FIELD OF THE INVENTION The present invention relates to electrical connectors and particularly to electrical connectors and contacts therefor which are suitable for mating with a plu-.' rality of square posts or pins. The present connector can be attached to the free end of a cable containing a plurality of individual wires so that the cable can be BACKGROUND: DESCRIPTION OF THE PRIOR ART A typical prior-art female contact for a square pin connector of the types aforedescribed is shown in US Pat. No. 3,363,224 to Gluntz, issued Jan. 9, 1968. Such a contact, and connectors using such contacts, had numerous disadvantages. Briefly such disadvantages are:
1. Such contacts have no provision for preventing male pins from being inserted at a skewed angle.
Since such skewed entry could easily damage the spring fingers of the female contact, such female contacts require costly anti-overstress means to limit displacement of the spring fingers.
. Such contacts have no provision to limit the depth of insertion of the male pins. Thus a male pin could be inserted so far into the female contact that it protruded out the rear of the female contact. Such rear protrusion is undesirable because the protruding male pin may touch adjacent contacts or other electrical components, causing shorts, circuit damage, etc.,
. Such contacts, when viewed from the direction of mating, have a closed box" configuration which was retained only by the inherent strength of bends in the material. Thus the box could easily be spread open and the accuracy of the final dimensions of the contact could be destroyed during usage. Moreover the contact could not be fabricated with accurate final dimensions because its closed box configuration prevented overfolding of the contact during production, whereby the contact could not spring back slightly to the desired final position.
4. In the version of the contact designed to be crimped to a wire and inserted into an insulator, there was no provision to lock the contact in a cavity of an insulator housing and thereafter unlock the contact to remove it from the housing.
5. The mating areas of the spring fingers of the contact were located near the rear of the contact housing; thus it was necessary to insert a male pin very deeply into the contact to effect proper matmg.
6. The spring fingers of the contact flexed in a direction parallel to the line of male pins which were mated with the contact; thus accumulated tolerance errors along a row of such male pins caused some of the male pins in the row to mate improperly with such spring fingers, often overstrcssing one spring finger and not engaging the other spring finger of a pair.
7. Since the contact has a four-sided box conligurw tion with a closed seam, it is difficult to make mass production tooling for the contact and to plate completely.
Accordingly several objects of the present invention are to provide a connector for mating with one or more freestanding square male pins which (I cannot receive such pins in a skewed direction, thereby precluding the possibility of damage to the female contacts of such connector (2) will not allow the male pin to protrude from the rear of the female contact, thereby precluding such pins from contacting separate electrical components or other contacts, whereby shorts and circuit damage are avoided, (3) can easily be formed by mass production operations to close tolerances which will be retained during the life of the contact, (4) has a contact which can easily be locked within and removed from an insulator housing in a reliable manner, (5) has a contact with mating areas near the front of such housing so that good contact can be effected even when the male pins are not inserted deeply, (6) can accomodate accumulated tolerance errors along a row of mating male pins without improper positioning of such pins within the contacts spring fingers, and (7) has a contact which is relatively easy to tool and plate. Other objects and advantages are (8) the provision of a contact with an increased spring length and (9) the provision of a two tier connector with reduced insertion force. Further objects and advantages of the present invention will become apparent from a consideration of the ensuing description thereof.
DRAWINGS In the drawings, which illustrate various embodiments and details of the invention,
FIG. 1 shows a crimp and insert contact,
FIG. 2 shows a contact for a single tier PC boardmounted connector,
FIG. 3 shows details of the locking feature of a contact for the lower tier of a double tier PC boardmounted connector,
FIG. 4 shows details of the locking of the contact of FIG. 1 in an insulator housing,
FIG. 5 is a front view of FIG. 4,
FIG. 6 shows details of the locking of the contact of FIG. 2 in an insulator housing,
FIG. 7 is a sectional view of a two tier PC connector,
FIG. 8 is a sectional view taken along the lines 88 of FIG. 7, and
FIG. 9 shows a cable connector using contacts of FIG. 1, together with mounted mating pins.
DESCRIPTION In the description of the present invention, four types of contacts will be described, namely: (1) a crimp and insert contact, (2) a contact for a single tier PC boardmounted connector, (3) a contact for the lower tier of a double tier PC board-mounted connector, and (4) a contact for the upper tier of a PC board-mounted connector. These types are exemplary only; many other types of contacts within the scope of the present invention will be apparent to those skilled in the art.
FIG. 1 shows a crimp and insert contact attached to a wire. The contact is designed to be crimped around the end of a wire from which a predetermined length of insulation has been removed, whereafter the contact can be inserted into a specially designed cavity in an insulator housing. Upon such insertion, the contact will automatically lock itself in the insulator housing. If it is necessary to remove the contact (due to damage, circuit changes, etc.) a special release tool is used.
The contact comprises a rear wire grasping section which is designed to be crimped around the end of a wire, a middle body section 12 which is designed to receive and effect an electrical connection with a square male contact pin, and a forward locking section 14 whichis designed to releasably lock the contact in the cavity of an insulator housing.
Wire grasping section 10 comprises two pair of wire grasping tabs 16 and 18 of conventional design which can be inserted, along with an end-stripped wire 20, into a conventional crimping tool. Operation of the tool crimps tabs 16 around the insulated portion of the wire and crimps tabs 18 around the stripped portion of the wire, as indicated.
Wire grasping section 10 is joined to body section 12 by a joinder portion 22 which curves outwardly from the section 10 to the center portion of body section 12 such that when the contact is crimped to wire 20, wires will be coaxial with a central axis of body section 12.
Body section 12 comprises a three sided channel which has been folded from a metal blank. Two spring fingers 24 and 26 have been struck out of the respective sides of the channel. The end of each spring finger 24 or 26 comprises a convex mating portion which faces a similar convex mating portion of the opposite spring finger such that when a male contact pin of the type shown in FIG. 9 is inserted between spring fingers 24 and 26, such convex mating portions will be spread apart and ride along the sides of the contact finger to make a good electrical connection therewith. The edge of each of contact fingers 24 and 26 is separated from the rest of body section 12 of the contact by spacing, such as indicated at 28, so that the contact can readily be plated. In absence of spacing 28, the edges of the contact fingers would lie very close to the adjoining edges of the body section and actually contact such adjoining edges near the bases of the fingers, which would render it very difficult for an electroplating solution to reach all edges of the body section.
U-shaped body section 12 is formed from a section of a flat blank by making two right angle bends along parallel lines 30 and 32. Prior to such bending, a major portion of the metal along each intended fold line is removed, as indicated at 34, such that the actual fold lines will occur only along the end portions of the section of the blank. This will reduce the force required to effect such folds and also will reduce the tendency of the channel to spring back after completion of the fold. Thereby the fold may be made more accurately and predictably in a mass production operation.
The contact is reinforced at the rear end adjacent the bases of the spring fingers 24 and 26 by a reinforcing back plate 36 which has been formed by a right angle bend (prior to forming the channel) from an extension of one side of the channel and inserted (during bending of the channel) by force fit into a slot 38 in the other side of the channel. Slot 38 has a tapering lead-in portion to facilitate such insertion. Preferably the edge of the end of back plate 36 is flush with the edges of the side of the channel which includes slot 38. In addition to reinforcing the back portion of body section 12, backplate 36 also provides a stop to prevent the male pin from being inserted far enough to protrude out the rear of the contact, where it might touch other contacts or electrical components and thereby cause damage, as aforementioned.
Locking section 14 of the contact comprises a forward extension of the center portion of the channel. Section 14 includes side notches 40 and 42, two curved fingers 44 and 46, and a front notch 48. During insertion, fingers 44 and 46 lock over a pair of shoulders in the cavity of the insulator housing, as indicated in FIG. 4. Notch 48 accomodates a front guide boss 68 (FIG. 4) of the insulator housing and notches 40 and 42 increase the flexibility of section 14.
FIG. 2 shows a contact having a body section 12 similar to that of the contact of FIG. 1, but which does not have any locking or wire grasping sections of the type shown in FIG. 1. In lieu of such wire grasping and locking sections, one side of the channel portion has extensions at the respective ends thereof which are bent downwardly to form front and rear portions 50 and 52. Front portion 50 is not attached to the other side of the channel or to the center panel of the channel but is held in position merely as a cantilevered beam. Portion 50 includes a square aperture 54 with tapered lead-in sides to accomodate and guide the male pin during its insertion. It also includes a mounting tab 55 which can be inserted through an aperture in a PC board and soldered to such board.
Rear portion 52 comprises an extension of the reinforcing back plate 36. Portion 52 is thus retained to the lower side wall of the channel by means of the aforementioned interference fit in slot 38 and by a slot (not shown) which interlocks with slot 38 in the manner shown in FIG. 3. Portion 52 also has a mounting tab 55', similar to tab 55 of portion 50.
The contact of FIG. 2 is designed to be mounted within and insulator housing 74 (FIG. 6) having a single tier of contact cavities. Prior to bending front portion 50 downwardly as shown, the contact is inserted from the rear of the insulator, whereafter tab 50 is bent downwardly as indicated to lock the contact in the insulator. The resultant connector can be attached to a PC board (not shown) near its edge by inserting tabs 55 and 55 through holes in the board and soldering them to printed circuit conductors on the underside of the board.
The contact of FIG. 2 is unsuitable for the lower tier of a PC connector with two tiers (upper and lower) because the contacts rear portion 52 would lie on the outside of the insulator housing and thus interfere with the similar rear portion of the contact in the corresponding position in the upper tier (see 52', FIG. 7). Accordingly the lower tier contact for a double tier connector does not have a rear tab 52 but instead has a back plate 36 similar to that of FIG. 1. However as shown in FIG. 3, an extension 56 is formed from the rear of. the center panel of the channel; the extension includes a lock notch 58 and a curved lead-in portion 60. When modified as shown in FIG. 3, the contact is designed to be inserted in a cavity of an insulator housing from the front (with portion 50 (FIG. 2) already bent downwardly) until lead-in portion 60 rides over a boss 80 (FIGS. 7 8c 8) in the cavity and notch 58 locks around the boss.
FIGS. 4 and 5 show details of the insulator housing 64 and the manner in which the contact of FIG. 1 locks in the cavity 62 of housing 64. Housing 64 is shown in a cutaway and broken away view in FIG. 4, but appears in full view in FIG. 9. Cavity 62 extends through housing 64 from front to rear thereof and is generally rectangular, except for (l) a three-section ledge 66 which projects into the front portion of the cavity from the top and upper sides thereof, (2) a boss 68 which extends upwardly in the front portion of the cavity from the floor thereof, and (3) a pair of recesses 69 and 71 at the front of the floor of the cavity on either side of boss 68. Ledge 66 and boss 68 form a generally square opening which serves to guide the male pin so that it mates properly with the contacts spring fingers 24 and 26. The front surfaces of ledge 66 and boss 68 taper inwardly to guide the pin into this square opening. Recesses 69 and 71 provide shoulders so that curved fingers 44 and 46 can lock thereover.
The contact of FIG. 1 is inserted into cavity 62 from the rear of housing 64. Locking section 14 is inserted first, adjacent the floor of the cavity. The contact is pushed forward until body portion 12 thereof enters the cavity, whereupon chamfer surfaces 72 assist in camming body section 12 downward with respect to locking section 14 such that the contact bends slightly about the web interconnecting notches 40 and 42. As the contact moves forward, the ends of fingers 44 and 46 ride against the floor of cavity 62 and the upper edges of the sides of the channel portion ride against the roof of cavity 62."When the contact is almost fully forward, fingers 44 and 46 snap into recesses 69 and 71, allowing locking section 14 to return to its original orientation with respect to body section 12. When the contact is in final position it is blocked from further forward movement by ledge 65 and boss 68, but can be withdrawn rearwardly after fingers 44 and 46 are moved out of recesses 69 and 71, e.g., by using a forked removal tool.
FIG. 6 shows in detail the manner in which the front portion of the single tier contact (FIG. 2) locks in its insulator housing 74. The contact is inserted from the rear prior to bending front portion 50 down. When rear portion 52 contacts the rear of the insulator housing (which is similar to the front of the housing), front portion 50 is bent downwardly as illustrated, thereby locking the contact in the insulator. Thereafter the mounting tabs are inserted into holes in a PC board and the bottom portions of the tabs may be bent adjacent and soldered to printed circuit lines on the underside of the board to lock the entire connector to the board.
FIGS. 7 & 8
FIG. 7 is a sectional view of a two tier PC connector attached to a PC board 78 and FIG. 8 is a partial sectional view taken along the lines 88 of FIG. 7. A lower tier contact of the type partially shown in FIG. 3 is mounted in a lower tier cavity of the insulator, and an upper tier contact (not previously described) is mounted in an upper tier cavity of the insulator.
The upper tier contact has a front locking section 14 identical to that of the contact of FIG. 1 and a body section 12 with a rear portion 52' similar to but longer than rear portion 52 of the contact of FIG. 2 so that portion 52' can reach to the bottom of the insulator housing, whereby its tab 55" can extend through a hole in board 78 and be soldered to a PC conductor 84 on the underside of the board.
In the lower tier contact, the notch adjacent extension 56 is locked around a tapered boss 80, as previously described. Front mounting tab 50 extends downwardly through an opening in the PC board and is soldered to a different PC conductor 82.
The connector is assembled (prior to mounting it on board 78) by inserting each lower tier contact into its cavity from the front of the housing (until extension 56 snaps around boss and inserting each upper tier contact into its cavity from the rear of the housing (until its locking fingers 44 and 46 snap into recesses 69 and 71).
Since the position of the spring fingers of every contact of the upper tier is staggered with respect to the position of the spring fingers of every contact of the lower tier, the mating insertion force is substantially less than it would be if the spring fingers of the contacts of both tiers were in-line vertically. This is because when a component (FIG. 9) having two rows of extending male pins is plugged into the two tier connector of FIG. 7, the lower row of pins will meet the contacts of the lower tierJspread, and begin to move between spring fingers 24 and 26 thereof before the upper row of pins meets spring fingers 24 and 26 of the upper tier. Thereafter, as the pins of the lower row move between the spring fingers of the female contacts of the lower tier, the upper row of pins will similarly meet, spread, and move between spring fingers 24 and 26 of the contacts of the upper tier. Since the spreading of spring fingers 24 and 26 of the respective tiers occurs consecutively, rather than simultaneously, the mating insertion force is reduced since greater force is required to spread the spring fingers than to move a pin between the spring fingers once they have been spread.
FIG. 9 illustrates a full connector 64 designed to mate with a PC board 90 or other component having a plurality of parallel, freestanding, square male pins 88. The male pins can be located near the edge of board 90 as shown, can be located in the center of said board, or can be the male pins of an electrical component, such as a relay, functional circuit unit, etc. Connector 64 has two tiers of contacts, each of which is of the crimp and insert type shown in FIG. 1.
In the event a contact in connector 64 becomes damaged, the replacement thereof is a simple matter. A contact removal tool, consisting of a member having two protruding fingers, is inserted under the curved fingers 44 and 46 of the contact (FlG. 4) to bend locking section 14 upwardly so as to release fingers 44 and 46 from recesses 69 and 71. Thereafter the contact is pulled (by means of its wire) out the rear of the connector. The damaged contact is removed from the wire and replaced with a new contact, which is then inserted into the connector.
Similar techniques may be used to unlock the contact of FIG. 3 from its insulator. The contact of FlG. 2 can be unlocked by unbending the front mating tab 50 and then withdrawing the contact out the rear of the insulator.
It is thus seen that the contacts and connectors of the present invention overcome the disadvantages of the prior art connectors, i.e., (1) they do not permit a skewed entry of the male pin so that the possibility of damage to the female contact is precluded, (2) the mating pin cannot pass completely through the female contact and extend out the rear of the connector where it can cause possible circuit damage, (3) since the contact has three sides, it can be overfolded slightly to allow for a slight spring back to the desired final position and is locked in final position by force fit of the reinforcing back panel 36 in slot 38, thereby providing high accuracy of location of the spring fingers 24 and 26 and precluding the possibility of deformation due to the forces incurred during pin insertion, (4) the crimp and insert contact can easily be locked into and removed from its cavity in the insulator housing, (5) since the contact mating areas are located near the front of the housing, a pin does not have to be inserted all the way into the housing to effect a good connection, (6) since the spring fingers flex in a direction perpendicular to the line of mating pins, tolerance errors which build up along the line of mating pins will merely shift the position of the mating pin in a lateral direction with respect to the contact fingers and will not damage the fingers, as could be the case if the contacts were mounted such that the fingers flexed in a direction parallel to the row of mating pins, and (7) the provision of a three sided (channel) structure facilitates mass production tooling and plating.
Although the above description contains many specificities, these are not intended to limit the scope of the invention, but merely to exemplify one preferred embodiment thereof. The true scope of the invention is intended to be indicated by the subject matter of the appended claims and their legal equivalents.
l. A female contact for mating with a square pin, said contact comprising a sheet metal blank which has been folded along two spaced parallel lines to form a threesided channel structure having an open side and a general U-shape when viewed from an end of said channel in a direction parallel to said fold lines, a pair of spring fingers projecting inwardly from corresponding locations on the respective opposing sides of said channel, the free end of each of said spring fingers having a curved convex surface facing the corresponding surface on the opposing spring finger, and an end portion of one end of one opposing side of said channel being folded inwardly along a third fold line perpendicular to said parallel fold lines and inserted, by force fit, into a slit formed in the other opposing side of said channel at a location opposite said third fold line,
thereby to reinforce said structure, said contact having means for mounting and locking same in a cavity in an insulator body and for making an electrical connection to an electrical conductor.
2. The contact of claim 1 wherein said means for locking and mounting said contact in an insulator body comprises an extension of the center side of said channel member which projects from one end of said channel, generally in the same plane as said center side, said extension having means for locking said contact on a shoulder in an insulator cavity such that when said contact is inserted into said cavity, said extension will ride over said shoulder to enable said means automatically to lock on said shoulder.
3. The contact of claim 2 wherein said means on said extension comprises fingers shaped to ride against the floor of said cavity during insertion of said contact such that said fingers will snap into a respective pair of recesses on the floor of said cavity.
4. The contact of claim 1 wherein said means for mounting and locking said contact in an insulator cavity comprises an elongated extension projecting from one of said opposing sides of said channel, whereby said elongated extension can be folded over after insertion of said contact in a cavity of an insulator in order to prevent said contact from moving in one direction with respect to said insulator and so that the end of said extension can be inserted into a hole in a printed circuit board for mounting and effecting an electrical connection.
5. The contact of claim 4 wherein said contact has two elongated extensions projecting from the respective ends of said one of said opposing sides of said channel, whereby said elongated extensions can be folded over after insertion of said contact in a cavity of an insulator in order to prevent said contact from moving in two directions with respect to said insulator.
6. The contact of claim 1 wherein each edge of each of said spring fingers is spaced from all other portions of said contact so that all portions of said contact, including the edges of said spring fingers, can be plated in an electroplating tank.
7. The contact of claim 1 wherein said sheet metal blank includes an opening along each of said two parallel fold lines, each of said openings extending a major fraction of the length of said channel along a portion of said channel spaced from the ends thereof.
8. The contact of claim 1 further including an insulating housing having a cavity extending therethrough from one surface thereof to an opposing surface thereof, said contact being mounted in said cavity, one portion of said cavity adjacent said one surface. thereof comprising a tapered lead-in portion having a wide mouth at said one surface which tapers to a narrower throat at a portion spaced from said one surface.
9. The contact of claim 8 wherein said insulating housing includes at least two contacts mounted in two respective cavities therein, one of said contacts being mounted such that the spacing between its spring fingers and said one surface of said housing differs from the corresponding spacing of the fingers of the' other of said contacts, whereby the force required to mate two of said pins with said contacts will be less than that required if said spacings were identical.
10. The contact of claim 8 wherein said means for locking and mounting said contact in an insulator body comprises an extension of the center side of said channel member which projects from one end of said channel generally in the same plane as said center side, said extension having a pair of fingers thereon, one side of said cavity of said insulator having a corresponding pair of recesses spaced such that said fingers can lock over