Patent Publication Number: US-4585293-A

Title: Elastic press-in for the solderless connection of the winding posts of electric connectors or the like with through-connected printed wiring boards

Description:
BACKGROUND OF THE INVENTION 
     The present invention is directed to a contact pin for insertion into contacting engagement with a through-opening in a printed circuit board. A deformed elastic section of the pin affords the contact between the pin and the opening in the board. 
     Insertable elastic pins of the type mentioned above have the basic task of compensating for manufacturing tolerances in the diameter of the metallic surfaced through-openings in printed board circuit; they have been known for some time, for example, from DE-OS 26 56 736 in the form so that over a certain partial section of the post or pin length they have an approximately C-shaped cross-section, which, initially, permits a diameter variation or diameter adaptation to different hole diameters in the printed boards and secondly, by a snug fit in the board opening also affords the required contact pressure. Now while the task of the diameter adaptation may be considered more or less well resolved in this known design, the integrity of the contact itself is very insufficient; this is attributable to the fact that the specific contact pressure of the C-shaped section of the post with the hole wall is very low due to the relatively large contact area, so that a so-called hermetic union can never result, but instead one must reckon with corrosion phenomena at the contact locations. 
     SUMMARY OF THE INVENTION 
     It is, therefore, the object of the present invention to eliminate the above cited disadvantages of the pins known from DE-OS 26 56 736 and to provide a pin form which along with high diameter elasticity in the cross-section also results in good edge compression contact with printed board openings. 
     This problem is solved by the subject matter indicated in the patent claims, and the specific details and advantages of which are explained more specifically in the description of two embodiments. 
     Besides the above-mentioned DE-OS 26 56 736, it is indeed further known from the likewise older DE-GM (German Utility Model) 81 05 896 how to form insertable pins with an approximately M-, N- or X-shaped cross section as the contact zone, that is, to give the basic cross-section an edge, in order to get good contact points. The disadvantage of this design is, however, that these cross-sectional shapes have only a very low elasticity or deformability, because in the required bending regions there are still relatively strong (thick) material zones which stiffen the basic shape. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     In the drawings: 
     FIG. 1 shows the cross section, according to the invention, of the contact section of a wound post or pin with a shaping die; 
     FIG. 2 is a partial view of a plug connector including the wound posts according to the invention; 
     FIG. 3 is a cross-sectional view of the deformed section of the post in a printed circuit board hole; 
     FIG. 4 is a view similar to FIG. 3 with the post inserted into a smaller hole; and 
     FIG. 5 is a cross-sectional view of another embodiment of the deformed post. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     An axially extending elastic deformed section B (FIG. 2) of a wound post or pin 5 of a plug connector 6 according to the invention, is illustrated in transverse section in FIGS. 3 to 5. The plug connector 6 is illustrated schematically in FIG. 2, and has the outstanding feature that the basic cross-sectional form is appoximately U-shaped, 3,4 or V-shaped 9,10. The U-shaped section is made up of a bight portion or base 3 with legs 4 extending outwardly from the opposite base. A transition portion E connects the opposite sides of the base 3 with the legs 4 and has a reduced thickness as compared with the legs. 
     The V-shaped section in FIG. 5 has a base 10 with legs 9 extending outwardly from the base. In FIGS. 3 and 4 the outside surface of the transition portion E is concave and is formed by an arc of a circle. The outwardly directed edges R 1 , R 2  at the opposite ends of each of the free legs 4 form contact lines as shown with rounded surfaces, however, the contact lines need not be rounded. It is further provided according to the invention that the wall thickness of the base 3 or 10 is equal to or smaller than that of the transition portions E or E 1 . The material of the base 3, 10 connecting and thereby stiffening the legs 4, 9 extends outside the center of gravity S. By this arrangement a transverse elasticity is obtained which, as is evident especially from FIGS. 3 and 4, makes it possible to press or insert contact pins of equal size into the metallic surfaced walls 7a, 7a&#39; of different size board openings 7, 7&#39; in such a way that at the contact edges R 1 , R 2  or respectively R 3 , R 4 , gastight and hence corrosion-proof junctions or contact surfaces are formed. Thus, whether a circuit board opening is smaller or larger--due to the manufacturing tolerances--will determine how the width w changes when the pin is inserted into a board opening. 
     In a simple, exact and hence wasteproof manner, the elastic deformed sections B according to the invention are to be manufactured in a die according to the schematic representation in FIG. 1. The die is formed by a die bottom part 1 which fixes the pin width b in a cutout or recess of an equal width a, with formed-in bulges 1a forming the elastic transition portion E between the base 3 and the legs 4 and a correlated die top part 2, whose centered ram 2a serves essentially to form the profile or inside surface 3a, E&#39;, 4a of the deformed section B. The lateral regions 2b of top part 2 serves to form the legs 4 with their outer contact edges R 2 . In this manner, individual execution of the shaped deformed sections B on the wound posts or pins 5 during their manufacture or subsequent(ly) on plug connectors 6 of any model already equipped with posts 5 is possible, as has not been the case with the insertable pins known to-date.