Electrical connector with pin retention feature

Abstract: An electrical connector comprising a header (10) with a plurality of terminal pins (12) having means for retaining the header in position during soldering to a printed circuit board. Retention is accomplished by an offset formed as a crimp at the insertion end of at least one pair of the pins (12A, 12B). The crimps exert opposite normal forces against one surface of their respective holes to retain the header during soldering.

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to electrical connectors affixed to printed circuit boards and, more particularly, to a connector comprising a retainer having a plurality of pins mounted therein, the pins being stiff and extending outwardly from the retainer and having portions for insertion through respective holes of a printed circuit board. 2. Description of Related Art Since the advent of the printed circuit board, electrical components have generally been affixed to the board by soldering the component leads to the printed electrical pattern. Often times the component leads extend through the board's holes and must be soldered in this position. One of the problems encountered in such operations is maintaining the components in the desired position or orientation during assembly and soldering. Various attempts have been made to solve this problem. In earlier times when discrete electrical components such as capacitors and resistors were commonly affixed in large number to printed circuit boards, various lead locking arrangements were suggested. For example, in US-A-2,754,486 the two relatively soft lead wires of a resistor were crimped in a configuration so when inserted, the leads temporarily lock in the substantially larger board holes by hooking around the bottom edge of the board holes to thereby hold the resistor in place while soldering. This document also discloses that the outer portions of the leads can be provided with a crimp projecting laterally toward the other lead and pressing against one side of the board hole, said outer portions being held at an inclination to each other by the engagement of said crimps, against the sides of said holes, to thereby hold said resistor in position until the projecting ends of said leads can be soldered. Similar approaches were proposed for capacitors in US-A-3,162,721, US-A-3,056,939, US-A-3,239,720 and US-A-3,747,045. Where such discrete components have been packaged together, similar techniques have been tried. US-A-3,524,108 for example, discloses a board mounted modular circuit component comprising a hard dielectric ceramic material supporting a number of active and passive components with multiple, self-locking leads bent into a configuration so as to provide cam surfaces for contacting the printed circuit board holes. From the AMP catalogue 85-773, issued November 1985 entitled AMPMODU MTE Interconnection system, p. 18 and 22 electrical connectors are known which have four posts mounted in a header assembly. A minimum of two locations per header assembly are provided with formed posts. The prospectus EH connector, JST Trading Company Ltd., September 1983 shows electrical connectors. These connectors comprise kinked pins for retention into respective holes of a printed circuit board. Retention during soldering is particularly important in connection with the more recent multi-terminal connectors. Where such connectors have flat, thin leads, which can be readily crimped as in the discrete components of the past, the retention is not a serious problem. This is because the easily crimped flat, thin leads usually have a large offset permitting adequate room to pass through the board holes. The crimped portion passes completely through holes and locks to the other end of the holes. To provide adequate retention, the thickness of the board and location are critical. In the case of electrical connector headers, lead locking arrangements of the prior art are not easily applied. Such headers include numerous male terminal pins surrounded by various plastics. The male pins are typically square metal posts approximately 1 mm (0.025 inches) square and are very stiff. Because of the size and stiffness of such square male pins, headers are soldered to printed circuit boards utilizing various hold-down devices to retain the header in place during the soldering operation. Such devices include mechanical fasteners such as bolts and screws. Weighted plates are also used. These are placed atop the headers and removed after the soldering process. Although such methods work, they are expensive because they are labor intensive. Within the last few years, methods of attachment which are an integral part of the header have been sought. What has been tried typical!y involves employing a single male pin in the header which will interfere with one printed circuit board hole. The male pin used is commonly one of the commercially available compliant-type pins. Such pins, however, usually require high insertion forces on the order of 178N (40 pounds). Also they are useful for one insertion only. The move to robotic insertion has lead to a need for a header that can be mechanically placed on a printed circuit board and automatically retained through subsequent board handling and soldering operations. Robotic loaders typically have an upper limit on insertion forces (for example, about 67N (15 pounds)) to protect the circuit board in case of a misplaced or damaged component. As this load limit is reached, the insertion head of the robotic loader retracts to provide this safety feature. Consequently, retention features must have relatively low insertion forces to be used with robotic loaders. STATEMENT OF INVENTION The present invention seeks to provide a solution for retaining an electrical connector in the correct position during soldering and other handling operations. According to the invention an electrical connector or header comprising a retainer of plastics material having a plurality of terminal pins mounted therein, the pins being relatively thick and stiff and extending from the retainer and having a longitudinal axis and end portions for insertion through respective holes of a printed circuit board; wherein the pins include at least one pair of pins having at the insertion portion of each pin an offset in the form of a crimp which causes the longitudinal axis to deviate in one direction and in an opposite direction relative to the uncrimped portion of the pin and the remainder of the pin adjacent the retainer with the insertion portions of the rest of the pins being straight; the crimp of one pin of said one pair of pins extends in a direction opposite to the crimp of the other pin of the pair, the crimp being arranged at said end portions and being so shaped that on insertion into the holes of the printed circuit board each pin with a crimp only contacts the printed circuit board with its crimp within its respective hole only on one side of said hole and at a region inwardly spaced from the end of the hole remote from the retainer and thereby exerts a relatively high normal force against said printed circuit board only at said one side of the hole which is opposite to the corresponding normal force exerted by the other crimped pin of the pair of pins in an opposing insertion hole to thereby act as retention means for retaining the connector in a position for soldering, whereby when the pins are all inserted in the holes in the printed circuit board and positioned for soldering, the connector is retained in position for soldering solely by the normal forces exerted by the crimped pins. The crimp or deformation is not dependent upon the thickness of the printed circuit board because retention depends upon the complementary normal forces of the pair of crimped pins against two opposing printed circuit board holes. The complementary action of each pin of the pair against the corresponding surface of the hole provides retention, no matter whether the board is relatively thin or thick. Also, the thick pins allow for very little room for offset without creating very high insertion forces. The independence of the crimp relative to the thickness of the printed circuit is to be understood with the proviso that the region of contact between the crimp and the hole inside the printed circuit board remains inwardly spaced from the end of the printed circuit board hole. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a first embodiment of the present invention illustrating a pair of crimped retaining pins in a double row vertical header. FIG. 1A is a top view of FIG. 1. FIG. 1B is a sectional view taken along the line B-B of FIG. 1A, after insertion in a printed circuit board. FIGS. 2, 2A and 2B are respectively similar views of a second embodiment of the present invention illustrating a pair of crimped retaining pins in a triple row vertical header. FIGS. 3, 3A, 3B and 3C are also respectively similar views of a third embodiment of the present invention illustrating two pairs of crimped retaining pins in a single row vertical header. FIGS. 4, 4A , and 4B are also respectively similar views of two pairs of crimped pins in a single row, right angle header. FIGS. 5, 5A and 5B are also respectively similar views of a pair of crimped retaining pins in a double row, right angle header. DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 illustrates a first embodiment of the present invention wherein a double row vertical header 10 is shown. The header comprises two rows of square male terminal pins 12. Such male terminal pins are an industry standard 1 mm (0.025 inches) square. The pins are held in a plastic retainer or wafer 14. In FIG. 1, a pair of adjoining pins. 12A and 12B, have been crimped as shown at their terminal or insertion end. In the embodiment shown, the deformation is such that the crimped portions of pins 12A and 12B extend toward each other. The retention feature of the present invention will work equally well if the crimped portions both extend away from each other. What is important is that each crimped portion of the pair cooperates against corresponding surfaces in the printed circuit board holes, as explained below. Buttons 16 are provided on the wafer 14 to provide an offset between wafer and printed circuit board after insertion of the header 10. This allows for adequate cleaning after the soldering operation. FIG. 1B illustrates the retention action of the pair of crimped pins 12A and 12B after the header 10 is inserted into a printed circuit board 18. The crimped end of the pins are shown within the holes of the board. It should be noted that retention can be achieved by contact of the crimped portion of each lead with only one side of its hole at points identified as 19A and 19B, respectively. The normal forces exerted against hole surfaces 19A and 19B by the crimped portion of pins 12A and 12B is sufficiently high to provide the necessary retention during the soldering operation. Since only one surface of each hole is necessary for retention, the thickness of the printed circuit board is not as critical as where retention due to a terminal or lead deformation requires contact with opposite sides of the same to circuit board hole. Thus the present invention operates equally well in very thin and very thick printed circuit boards with the proviso that the region of contact between the crimp of the pin and the hole of the printed circuit board remains inwardly spaced from the end of the printed circuit board hole. What is important is that at least a pair of complementary pins be similarly crimped so that normal forces of the crimped portion of each act cooperatively against the corresponding surface of each respective printed circuit board hole. FIGS. 2, 2A and 2B illustrate a second embodiment of the present invention where like parts are identified by the same reference number. This second embodiment shows a triple row vertical header 20 differing from header 10 essentially only in that it contains three instead of two rows of pins 12. A single pair of crimped terminals 12A and 12B is utilized here also, one from the first and third rows. They are separated by a regular pin 12. The retention action in the printed circuit board 18 is otherwise identical as shown in FIG. 2B. FIGS. 3, 3A and 3B illustrate a third embodiment of the present invention. The header 30 in the embodiment comprises but a single row of pins held in a plastic wafer 34 similar to 14 of the prior embodiments. Since only a single row is used, the retaining pins with crimped ends must be in the same row. In the embodiment of FIG. 3, two pairs of pins are crimped in alternating directions. One pair of oppositely crimped pins, however, will also provide adequate retention. Pairs 32A and 32B cooperate with one another as do pairs 32C and 32D in a manner similar to the single pair of crimped pins in the first two embodiments to provide retention of the header in the printed circuit board. Thus, as shown in FIG. 3B, complementary crimped terminals 32A (shown in solid) and 32B (shown in phantom) have their crimped portion exerting normal forces against opposite surfaces of their respective printed circuit board holes, thereby achieving the same retention action as in the prior embodiments. Likewise, the same is true for crimped terminals 32C (solid) and 32C (phantom) shown in FIG. 3D. FIGS. 4, 4A and 4B illustrate a fourth embodiment of the present invention. The header 40 is also a single row header but the terminal pins 42 are bent at right angles at one end. This is because header 40 is designed to be inserted into printed circuit board 48 at right angles as shown in FIG. 4C. As before, the pins 42 are held by a plastic wafer 44. Header 40 also has two pairs of pins crimped alternatively as in the header of FIG. 3. The crimps are at the right angle portion of the pins for obvious reasons. Thus, as in the case of the embodiment of FIG. 3, pairs 42A and 42B and pairs 42C and 42D of crimped terminals cooperate to retain the header in the printed circuit board 48. FIG. 4B illustrates the previously explained cooperative retaining action between crimped pin 42B (solid) and 42A (phantom). The same occurs in the case of pins 42C and 42D. Again, adequate retention can be obtained with a single pair of crimped pins. FIGS. 5, 5A and 5B illustrate a fifth embodiment of the present invention. The headers 50 is a double row, right angle header, meaning that it comprises a double row of pins 52 held by a wafer 54 where all the pins are set at right angles for insertion into a printed circuit board. A pair of pins 52A and 52B are crimped in the manner previously described. Thus, when the header 50 is inserted into the printed circuit board 58, crimped terminals cooperate as did crimped pins 12A and 12B ion the embodiment of FIG. 1 to retain header 50 in the proper position during soldering.

Claims: An electrical connector or header (10, 20, 30, 40, 50) comprising: a retainer (14, 34, 44, 54) of plastics material having a plurality of terminal pins (12, 32, 42, 52) mounted therein, the pins (12, 32, 42, 52) being relatively thick and stiff and extending from the retainer (14) and having a longitudinal axis and end portions for insertion through respective holes of a printed circuit board (18); wherein the pins include at least one pair of pins (12A, 12B; 32A-32D; 42A-42D; 52A, 52B) having at the insertion portion of each pin an offset in the form of a crimp which causes the longitudinal axis to deviate in one direction and in an opposite direction relative to the uncrimped portion of the pin and the remainder of the pin adjacent the retainer with the insertion portions of the rest of the pins being straight; the crimp of one pin of said one pair of pins extends in a direction opposite to the crimp of the other pin of the pair of pins, the crimp being arranged at said end portions and being so shaped that on insertion into the holes of the printed circuit board, each pin with a crimp only contacts the printed circuit board with its crimp within its respective hole and only on one side of said hole and at a region inwardly spaced from the end of the hole remote from the retainer and thereby exerts a relatively high normal force against said printed circuit board only at said one side of the hole which is opposite to the corresponding normal force exerted by the other pin of the pair of pins in an opposing insertion hole to thereby act as a retention means for retaining the connector in a position for soldering, whereby when the pins are all inserted in the holes in the printed circuit board and positioned for soldering, the connector is retained in position for soldering solely by the normal forces exerted by the crimped pins. An electrical connector according to claim 1 wherein said terminal pins have square cross-sections. An electrical connector according to claim 1 or claim 2 wherein the crimps of said pair of pins extend toward each other. An electrical connector according to claim 1 or claim 2 wherein the crimps of said pair of pins extend away from each other. An electrical connector according to any one of claims 1 to 4 wherein there are two rows of pins, each row containing one each of said pair of crimped pins. An electrical connector according to claim 5 wherein the insertion end of all the pins are formed at right angles to the remainder of said pins, the crimp of each pin of said pair being located at said right angle insertion end. An electrical connector according to any one of claims 1 to 4 wherein there are three rows of pins, two of said rows containing one each of said pairs of crimped pins. An electrical connector according to any one of claims 1 to 4 wherein there is a single row of pins and said pair of crimped pins is located in said single row. An electrical connector according to claim 8 wherein the insertion end of all the pins of the header are formed at right angles to the remainder of the pins, the crimp of each pin of said pair being located at said right angle insertion end. An electrical connector according to claim 8 or claim 9 and further comprising a second pair of crimped pins, both pins of each pair being positioned adjacent one another in the row. An electrical connector according to any one of the preceding claims wherein the rest of the plurality of pins extend through respective holes in the printed circuit board and are not required to be in contact with the printed circuit board until soldered thereto.

Inventors: DOUTRICH RAY CHARLES, DOUTRICH, RAY CHARLES
Applicants: DU PONT, E.I. DU PONT DE NEMOURS AND COMPANY
Application year: 1987
Main classification: H05K3
IPC codes: H05K3, H01R12