US 3923365 A
In a terminal, an engaging portion for engaging the walls of an aperture formed in a housing or a printed circuit board, in which the aperture is substantially rectangular in cross-sectional area configuration. The engaging portion comprises a pair of curved, substantially parallel beams extending longitudinally through the aperture. The two beams are curved in the same direction with the two ends of the concave sides of the beams pressing against one major wall of the aperture and the center portion of the convex side of the beam pressing against the other major wall of the aperture. Further, the two beams are bowed outwardly from each other with their side edges pressing against the side walls of the aperture, thereby producing an overall force-fit effect in which the aperture engaging portion of the terminal exerts force in all four directions against the sidewalls of the aperture and is rigidly secured therein.
Claims available in
Description (OCR text may contain errors)
United States Patent 1191 Lynch 1 1 PRESS FITTED TERMINAL POST  Inventor: James Edward Lynch, Harrisburg,
 Assignee: AMP Incorporated, Harrisburg, Pa.
 Filed: Nov. 5, 1974  Appl. No.: 521,020
 US. Cl 339/221 R  Int. Cl. HOIR 9/08  Field of Search .1 339/221 R, 221 M, 220 R, 339/217 R, 217 S, 252 R, 252 S, 252 P, 253
R, 176 R, 176 M, 176 MP, 17 R, 17 C, 17
Primary Examiner-Roy Lake Assistant ExaminerJames W. Davie Attorney, Agent, or Firm-William J. Keating, Esq.; Donald W. Phillion, Esq.
 ABSTRACT In a terminal, an engaging portion for engaging the walls of an aperture formed in a housing or a printed circuit board, in which the aperture is substantially rectangular in cross-sectional area configuration. The engaging portion comprises a pair of curved, substantially parallel beams extending longitudinally through the aperture. The two beams are curved in the same direction with the two ends of the concave sides of the beams pressing against one major wall of the aperture and the center portion of the convex side of the beam pressing against the other major wall of the aperture. Further, the two beams are bowed outwardly from each other with their side edges pressing against the side walls of the aperture, thereby producing an overall force-fit effect in which the aperture engaging portion of the terminal exerts force in all four directions against the sidewalls of the aperture and is rigidly secured therein.
9 Claims, 6 Drawing Figures U.S. Patent Dec. 2, 1975 Sheet 2 of3 3,923,365
Sheet 3 of 3 3,923,365
. 5 wu hnpni I QQHHHW m E m F 9 7 7 6 a x M H m 3 3 m 0 7 8 7 m m 5 mm M 2 w 9 m f 3 2 4 4 M n \Vf m y F US. Patent Dec. 2, 1975 PRESS FITTED TERWNAL POST BACKGROUND OF THE INVENTION This invention relates generally to terminals which are mountable in apertures in housings or circuit boards and more particularly it relates to that portion of the terminal which engages the walls of apertures forrned therefor in housings or circuit boards.
It is common practice today to force fit terminals, such as terminal posts, in apertures in housings or printed circuit boards. Such force fitted terminals have portions which are designed to effect such a friction fit or force fit against the walls forming the aperture in the housing or circuit board.
Even in those cases where the terminal is to be soldered to conductive pads formed on the surface of the printed circuit board, it is highly desirable to provide a circuit board engaging means on said terminal which has entry and withdrawal forces within predetermined limits and which will hold a terminal rigidly therein with a minimum of wobble or misalignment until soldering can be effected.
The foregoing characteristics of uniform entry and withdrawal forces of said terminals becomes particularly important when a plurality of terminals are inserted in a circuit board simultaneously as, for example, in a comb form wherein a plurality of such terminals are secured to a common carrier strip and are inserted through a row of holes formed therefor in a printed circuit board by some appropriate insertion apparatus or machinery. When the terminals are to be soldered, the carrier strip is sometimes broken off after the insertion of terminals, and before soldering occurs. In such cases, if one of the terminals fits too loosely in its hold, it can easily become misaligned or, in certain extreme cases, can slip out of the hole.
In other cases, where terminals fit too tightly within holes, enough pressure can build up in the printed circuit board housing or break the plastic housing or printed circuit board.
In some applications terminal posts are inserted through holes in a printed circuit board on a piece-bypiece basis by means of computer controlled insertion equipment. As in the case of gang insertion of terminals, all terminals do not have exactly the same dimensions, nor do all holes in a circuit board have the same dimensions. Thus, in piece-by-piece insertion if a terminal is too loose, misalignment or even non-retention of the terminal can occur. If a terminal fits too tightly, the hole wall can be damaged. Such damage is particularly likely to occur when the hole is plated-through. The tight fitting terminal can crumble the plated-through metal resulting in poor electrical connection.
In other instances it is desirable to insert a terminal post in a connector housing or a printed circuit board and then, for some reason, to remove the terminal and then reinsert it, either in the same hole or in another hole. If the first hole in which the terminal was inserted was too small or the hole engaging portion of the terminal too large, the said hole engaging portion can become deformed and will not properly engage the wall of the next hole in which it is inserted.
BRIEF STATEMENT OF THE INVENTION In accordance with a primary object of the invention there is provided a aperture wall engaging portion which will provide a spring-like force upon the sides of the wall in all directions, in a plane perpendicular to the axis of the hole in which the terminal is inserted.
A second aim of the invention is an aperture wall engaging portion having a pair of substantially parallel curved spring members each of which has its two ends on its concave side pressing against one major wall surface of a hole, having a rectangularly-shaped cross section, in a given direction, and the middle portion of the convex side forced against the opposite major wall of the hole in the opposite direction, and each of which is curved outwardly from each other to provide forces against the walls of the hole at right angles to said first directional forces.
A third primary object of the invention is to provide a terminal having a portion thereof which engages the walls of a hole of rectangularly-shaped cross section formed in a printed circuit board or other housing, and in which said aperture engaging portion consists of a pair of substantially parallel and curved resilient beam members, with the ends of each of the beams applying force at their ends against one wall of the aperture in opposition to the force applied to the other side of the aperture by the convex center of the beam, and in which said beams are bowed outwardly with respect to each other to provide additional forces on the walls of the holes in directions substantially from the direction of said first forces.
A fourth aim of the invention is to provide a terminal post having a circuit board aperture engaging portion constructed to grip the walls of a circuit board aperture comprising a pair of parallel curved spring-like beam members each of which independently exerts force against the major sides of the aperture which has a rectangularly-shaped cross section, and also against the minor sides of the aperture.
A fifth purpose of the invention is to provide a terminal having a supporting body engaging portion which is spring-like in nature and which will adapt to fit within rectangularly-shaped holes in said supporting body over a range of sizes of said rectangular holes and within the spring-like characteristics of said engaging portion.
A further aim of the invention is to provide a terminal post having a supportin g body engaging portion which has a spring-like characteristic and which will fit into a substantially large range of rectangular hole sizes because of such spring-like characteristics, with the inser tion and withdrawal force of said terminal remaining within predetermined permissible limits.
A still further aim of the invention is a terminal having a supporting body engaging means which has a spring-like characteristic, thereby enabling said supporting body engaging means to fit a large range of cross-sectional areas of holes without permanently distorting the supporting body engaging portion of said terminal post.
A still further aim of the invention is the improve ment of force fit type terminals, and particularly terminal posts, in general.
In accordance with the invention there is provided a portion of a terminal (usually a terminal having a terminal post thereon), which is constructed to engage by force fit or friction fit the walls of an aperture formed in a housing or a printed circuit board. The aperture wall engaging portion of said terminal comprises a pair of curved, spring-like beam members which are substantially parallel with each other and also with the longitudinal axis of the aperture. The aperture preferably has a rectangularly-shaped cross-sectional area or it can have a cross-sectional area in the shape of a Maltese cross. On their concave side, the two parallel spring beam-like members have their ends pressed against one wall, herein defined as a major wall surface of the aperture, and on their convex side the two beams have their center portion pressed against the opposite major surface wall of the aperture. The two spring-like beams are also curved in directions away from each other so as to present convex surfaces to the two sidewall surfaces of the aperture. Thus, each of the two curved beam members are positioned under pressure in the aperture with forces exerted thereby against each of the opposite major surfaces and also against each of the sidewalls. The net result is that spring-like forces are exerted by the aperture wall engaging portion of the terminal in all four directions against the aperture walls in a plane substantially normal to the longitudinal axis of the aperture.
In accordance with a feature of the invention the two spring-like beams function substantially independently of each other to minimize distortion of the terminal when it is fitted into an aperture in which the forces between the two spring-like members and the aperture walls are not the same because of variations in dimensions both of the aperture and also of the beams.
In accordance with another feature of the invention, because the two spring-like beams are separated by a predetermined distance and function substantially independently of each other, said beams function to compensate for different sizes in the aperture in the housing or printed circuit board. Thus, within limits, if a hole is too small, the beams will be forced towards each other and tend to straighten out to accommodate said smaller hole, but will tend to stay within their elastic limits so that if withdrawn from said hole, will spring back to a shape essentially the same as their original shape. On the other hand, within limits, if a hole is too large, because of the two curved configuration beams, the said beams will span the distance between the two major walls of the aperture and also the distance between said beams and said aperture walls.
Obviously, there is a limit to the range of sizes of apertures into which the terminals can be inserted successfully. However, such range is larger than obtainable with most terminals currently available on the market.
BRIEF DESCRIPTION OF THE DRAWINGS The above-mentioned and other objects and features of the invention will be more fully understood from the following detailed description thereof when read in conjunction with the drawings in which:
FIG. 1 is a broken away, perspective view of four terminals mounted in a housing or circuit board;
FIG. 2 is a perspective view of a single terminal;
FIG. 3 is a plan view of a pair of terminals of the type shown in FIG. 2 and attached to a common carrier;
FIG. 4 is a side view of one of the terminals of FIG.
FIG. 5 is a plan view of another form of the terminal; and
FIG. 6 is a side view of the structure of FIG. 5.
DETAILED DESCRIPTION OF THE INVENTION Referring now to FIG. 1 there is shown a partially broken away perspective view of four terminals 9, 10, 11 and 12 each inserted through separate apertures 98, 35, 97 and 99 of retaining body 40, which can be a connector housing or a printed circuit board, and in particular shows the structure of that portion of the terminal which engages the walls of the aperture through which it is inserted.
Since all four terminals have similar structure, a description of only one of said terminals, namely terminal 10 and the circuit board engaging portion thereof will be described in detail.
The terminal 10 has an upper portion 16 extending above the upper surface 41 of the board 40 and a lower portion 22 extending below the printed circuit board 40. The lower portion 22 can be a tenninal post, for example, and the upper portion 16 can be one of the pair of mating terminals adapted to receive a male pin (not shown) thereinbetween.
The center portion 17 of the terminal 10 is that portion which is designed to grip the walls of the aperture 35. Said center portion 17, which is also identified herein as a housing or aperture wall engaging portion, is comprised of two leg portions 18 and 19 which are formed of a spring-like material such as a brass alloy, and which are generally parallel with each other and separated by a distance determined by the size of the hole 34 thereinbetween. The existence of said hole 34 defines the two spring-like beams 18 and 19 on either side thereof.
The hole 34 is not necessarily of any particular configuration. It can be round, oval, rectangular or square in shape. The important function of the aperture or hole 34 is to define two beams, such as beams 18 and 19, on either side thereof.
The two spring-like elements 18 and 19 are curved in a manner and to a degree, with respect to the size of the rectangularly-shaped hole 35, as shown in FIG. 1. More specifically, the dimensions of the beams 18 and 19, the amount of curvature the rein, and the size of the hole 35 are such that the ends 27 and 24 of the convex portion of beam 18, for example, exerts a force against the major wall 42 of the aperture 35, as indicated by the arrows 30 and 31.
The middle portion 25 of the other side of the curved beam 18 applies a force against the other major surface 26 of aperture 35 in the direction indicated by arrow 27.
In a similar manner the ends of the curved beam 19 exert forces against the major surface 42 of aperture 35 and the midpoint of the convex other side thereof exerts a force against the major surface 26 of aperture 35.
While it cannot be seen clearly in FIG. 1 the two beams 18 and 19 are also curved outwardly from each other in the directions of arrows 32 and 33 respectively. Thus, the outer side edges of beams 18 and 19 exert forces against opposite sides of the aperture 35. For example, the outer side of beam 19 exerts the force 33 on sidewall 45 of aperture 35.
The portion 22 of terminal 10 has been twisted in the general area 23 so as to be at right angles to the portion 36 of terminal 10. Such twisted portion is not a part of the invention per se. It simply shows one means for further securing the terminal in a circuit board and preventing unauthorized withdrawal of said terminal as well as adding some structural strength to the mechanical joining of terminal 10 and board 40. It is to be noted that aperture 35 is widened at the shoulder 46 in the circuit board or housing 40. This enlarged width of aperture 35 facilitates the twisting of the portion 22 of terminal 10. Another shoulder 47 is formed on the portion 22 of terminal 10 and abuts against the lower surface of the housing or printed circuit board 40.
Referring now to FIG. 2 there is shown a perspective view of a single terminal of the general type shown in FIG. 1, but without the presence of a housing and without the bottom portion 22 being twisted at right angles to the portion 36. All the portions of theterminal of FIG. 2 are identified by the same reference characters which identify corresponding portions of the terminal of FIG. 1. In addition it can be seenthat the lower portion 22 terminates in a spade-like configuration which can be received by a pair of leaf terminals or a female receptacle. The tip 51 can be of a shape other than the spade shape shown in FIG. 2. For example, it can be a frustum of conical or pyramidal configuration.
If desired, the upper end of the terminal of FIG. 2 can be bifurcated by slot 53 to form two contact elements 13 and 14, which terminate in tabs 48 and 49. The contact of FIG. 2 can be used in facing pairs, as shown by contacts and 11 of FIG. 1, with the contact surfaces 50 facing each other and with the tab-like portions 48 and 49 being held back in a pre-stressed condition by some appropriate shoulder or tab means formed on the retaining housing member. Thus, the pair of contacts, such as contact 10, can receive a male contact therebetween, with the surfaces 50 making contact with said male contact, between the contacts 10 and 11 of FIG. 1 for example.
It is to be understood that the particular configuration of the upper part of the terminal is not a part of the invention per se.
Referring now to FIG. 3 there is shown a plan view of two of the contacts of the type shown in FIGS. 1 and 2 on a carrier strip 57. These two contacts are identified by reference characters 10 and 56, with contact 10 representing the same contact 10 as shown in FIG. 2.
The remaining portions of the contact 10 of FIG. 3 are identified by reference characters corresponding to the reference characters identifying corresponding portions of the contact 10 of FIGS. 1 and 2. In addition, however, in FIG. 3, the carrier strip 57 and sprocket holes 58 are also shown. Further, in FIG. 3, embossed portions 60 and 61 are shown in bifurcated contact portion 48 and bifurcated and embossed portions 62 and 63 are shown on the bifurcated contact leg 49.
Referring now to FIG. 4 there is shown a side view of the terminal 10 of FIG. 3 with corresponding portions thereof being identified by the same reference characters as in FIG. 3. In FIG. 4 the curvature of the vertical housing engaging portion 17 can be easily seen.
It will be observed in FIG. 4 that the width of the beam, such as beam 18, is greater than the thickness of the upper portion 16 of the terminal, that is the portion 16 above the surface of the housing or printed circuit board in which the terminal is inserted, as shown in FIG. 1 for example. No difference in thickness between the upper portion 16 and the beams of the housing engaging portions 17 is not absolutely necessary. It is employed only in those cases where greater strength and greater spring force is required in the beams than is required in the upper portion 16 of the contact.
Referring now to FIG. 5 there is shown another form of the invention. In FIG. 5 the two spring-like members 73 and 72 which fit into printed circuit board aperture have tapered outer edges 90 and 91, rather than the convex arrangement of the structure of FIGS. 1, 2 and 3. The tapered edges 90 and 91 form an overall wedgeshaped structure which is inserted into an aperture in a printed circuit board or housing and is, in fact wedged,
6 against the walls of said aperture to secure the terminal therein.
The portion of the terminal 70 has no narrow portion comparable to the narrow portion 36 of the structure of FIG. 3. The reason for the absence of such narrowed portion in the area 75 of the structure of FIG. 5 is due to the fact that the post 92 of the terminal of FIG. 5 is not designed to be twisted at right angles with respect to the remainder of terminal 70, as is the post of FIG. 3.
The upper portions of the two terminals 70 of FIG. 5 can be bifurcated, if desired. Specifically, in contact 70, the upper portion is bifurcated to form two legs 79 and 78 which have a curved profile as shown in the side view of FIG. 6.
It is to be understood that the forms of the invention shown and described herein are but preferred embodiments thereof and that various changes can be made in the details thereof without departing from the spirit or scope of the invention.
I claim: 1. In a terminal constructed to be frictionally secured in a securing body within an aperture defined by walls to have a rectangular cross-sectional area, and having an upper terminal portion, and a lower terminal portion, an aperture wall-engaging portion connecting said upper portion to said lower portion and positioned within said aperture, and comprising:
first and second substantially parallel beam members spaced apart and each secured at its two ends to said first and second terminal portions of said terminal;
said first and second beams each being bowed in a first direction towards a first wall of said aperture an amount to place said beams in a spring compression force between the two opposing walls of said aperture including said first wall; and
said first and second beams further being bowed outwardly in opposite directions from one another by an amount to exert a spring compression force between the two remaining walls of said aperture.
2. An engaging portion as in claim 1 in which said securing body comprises a substrate; and
in which said terminal comprises a post having dimensions which will enable insertion thereof through said aperture.
3. An engaging portion as in claim 1 in which said securing body comprises a connector housing composed of an insulative material; and
in which said terminal comprises a post having dimensions which will enable insertion thereof through said aperture.
4. In a terminal constructed to be press fitted within an aperture in a terminal retaining body, with said aperture being defined by two parallel major surfaces and two parallel minor surfaces substantially perpendicular to said major surfaces, an engaging portion for frictionally engaging the walls of said terminal retaining body comprising:
first and second beam-like elements separated by an aperture formed through said engaging portion; said first and second beam-like elements being substantially parallel to each other and each being curved in the same direction to present a convex surface towards said first major surface and a concave surface towards said second major surface; said first and second beam-like elements being further curved in directions away from each other to 7 each present a convex surface towards opposite minor surfaces of said aperture; and
said engaging portion being of a size to have said first and second beam-like elements under compressive force between the major surfaces of said aperture and to be under compressive force between the minor surfaces of said aperture.
5. An engaging portion as in claim 4 in which said terminal retaining body comprises a substrate; and
in which said terminal comprises a post having dimensions which will enable insertion thereof through said aperture.
6. An engaging portion as in claim 4 in which said terminal retaining body comprises a connector housing composed of an insulative material; and
7. In a terminal an engaging portion positioned between the ends of said terminal and constructed to frictionally engage the walls of an aperture in a retaining body, said apertures having two facing major wall surfaces and two facing minor wall surfaces joining together the ends of said facing major wall surfaces and comprising:
first and second beam-like elements connected between the two end sections of said terminal and ex- 8 tending side-by-side longitudinally through said aperture;
said first and second beams each being bowed to have first convex surfaces which are adjacent a common major wall surface and second convex surfaces which are adjacent opposite minor wall surfaces of said aperture;
said engaging portion having overall dimensions in the direction normalto said major wall surface greater than the distance between said major wall surfaces and in the direction normal to said minor wall surfaces greater than the distance between said minor wall surfaces to exert a force against said major wall surfaces and said minor wall surfaces of said aperture when inserted therein.
8. An engaging portion as in claim 7 in which said terminal retaining body comprises a substrate; and
9. An engaging portion as in claim 7 in which said terminal retaining body comprises a connector housing composed of an insulative material; and