Patent Publication Number: US-3877769-A

Title: Circuit board socket

Description:
United States Patent 1 Berg, deceased et a1.  
 [451 Apr. 15, 1975 CIRCUIT BOARD SOCKET [75] Inventors: Quentin Berg, deceased, late of New Cumberland, Pa., by Frances 11. Berg, co-executor; Dauphin Deposit Trust C0 co-executor, New Cumberland, Pa.  
 [73] Assignee: E. l. du Pont de Nemours and Company, Wilmington, Del.  
 [22] Filed: Oct. 23, 1973 211 App]. No.: 408,445  
 [52] US. Cl 339/17 R; 339/94 R; 339/96; 339/116 C [51] Int. Cl. H05k 1/02 [58] Field of Search 339/17, 18, 60, 61, 94, 339/93, 96, 114-118, 278  
 [56] References Cited UNITED STATES PATENTS 2,439,589 4/1948 Sundell 339/96 X 2,448,832 9/1948 Ross 2,858,518 10/1958 Chrystie et a1. 339/94 M X 3,044,037 7/1962 Honig 339/116 C X 3,127,230 3/1964 Marquis et a1 339/96 X 3,158,420 11/1964 Olson et a1 339/96 R 3,241,095 3/1966 Phillips 339/116 C X 3,522,576 8/1970 Cairns 339/96 3,681,738 8/1972 Friend 339/17 R 3,781,770 12/1973 Mancini 339/259 R Primary ExaminerMarion Parsons, Jr. Assistant ExaminerTerrel1 P. Lewis Attorney, Agent, or FirmThomas Hooker [57] ABSTRACT A circuit board socket is provided with a silicone rubber seal to prevent flux, solder, or other impurities from entering the interior contact areas. Viscous liquid silicone rubber is applied to an opening communicating with the interior of the socket and flows completely into the opening prior to curing to form an effective seal. After the silicone rubber sets, it may be easily pierced by a lead inserted through the opening into the body of the connector for establishing electrical contact with a spring in the interior of the socket.  
 15 Claims, 5 Drawing Figures CIRCUIT BOARD SOCKET This invention relates to an improved circuit board socket of the type disclosed in United States Patent No. 3,681,738. These type sockets are mounted in holes extending through circuit boards and are fluxed and wave soldered to form permanent electrical connections between the exterior of the socket body and printed circuitry on the circuit board. The socket includes interior spring arms for forming a connection with a lead inserted through an opening in the socket and into engagement with the arm.  
  In the improved circuit board socket. the opening through which the lead is inserted for making contact with the interior socket spring arms is closed by flowing viscous room temperature curing silicone rubber into the opening so that the material, while still viscous. completely seals the opening and then cures or vulcanizes sufficiently to retain its position in the opening. thus positively sealing the opening and preventing flux. molten solder. or other contaminents entering the interior of the socket through the opening. The circuit board socket with a resilient plug or seal forms an improved barrier to the flow of molten solder into the interior of the socket body then provided in conventional sockets using solder resists.  
  The silicone rubber seal is easily penetrated by&#39; a lead inserted into the interior of the body. The seal has the additional advantage of tightly surrounding the lead inserted into the socket and thus preventing contaminents from entering the socket after insertion of the lead. When the lead is withdrawn. the resilient seal closes the opening formed by the lead and continues to seal the opening in the socket.  
  Other objects and features of the invention will become apparent as the description proceeds. especially when taken in conjunction with the accompanying drawings illustrating the invention. of which there is one sheet.  
 IN THE DRAWINGS FIG. 1 is a sectional view taken through a circuit board socket according to the invention;  
  FIG. 2 is a sectional view taken along line 22 of FIG. 1:  
 FlG. 3 is a top view of the socket of FIGS. 1 and 2;  
  FIG. 4 is a sectional view taken along line 4-4 of FIG. 1; and  
  FIG. 5 is a sectional view of a socket like that in FIG. 1 soldered in a circuit board hole with a lead inserted into the socket and in electrical connection with the interior spring arms.  
  The invention relates to a circuit board socket comprising an elongate metal cup 12 closed at end 14 and open at lead-receiving end or mouth 16. The mouth at end 16 is outwardly flared to facilitate reception of a lead inserted into the interior of the body 12. The circuit board socket 10 also includes a generally W-shaped spring member 18 having a pair of opposed spring arms 20 confined within body 12 and interconnected by bight portion 22 adjacent closed end 14 of the body. Spring curls 24 connect the ends of the spring arms 20 adjacent mouth 16 with exterior circuit board hole-engaging spring arms 26 extending along opposite exterior walls of the body 10. The spring 18 is formed of relatively high yield strength material and is held within the body 10 by a pair of inwardly directed opposed dimples 28 which extend into the interior of body 12 within the bight portion 22 of spring 18. As illustrated in FlGS. 1 and 4, portions 30 of the spring 18 extend through flared opening 16 of body 12. Body 12 and spring 18 are essentially identical to corresponding members disclosed in US Pat. No. 3.681.738.  
  After the spring 18 has been positioned in body 12 as shown in FIG. I. an amount of viscous room temperature curing silicone rubber is applied to the flared open end 16 between the portions 30. The silicone rubber liquid flows completely around the portions 30 and up to the interior walls 32 of mouth 16 to form a seal extending across the entire interior opening of the mouth. The rubber also flows down between the interior facing surfaces 34 of spring arms 20 to form a sealing plug 36. As illustrated in FIG. 2. the plug 36 extends to body side walls 38 adjacent flared mouth 16 and may narrow to a tip 40 separated from the side walls at a distance further away from the mouth 16. After application of the silicone rubber to the mouth of circuit board socket 10. the rubber is allowed to cure to solidify the plug in position in the socket as illustrated. The interior walls of body 12 are dry while the surfaces of spring arms 20 are coated with a material non-adherent to silicone rubber. When the viscous silicone rubber plug sets or cures. it adheres tightly to the dry interior surfaces of body 12 and forms an intimate non-adherent contact with the surfaces of the spring 18. The contact formed between the plug and both the body and spring tightly closes mouth 16 and prevents flux. molten solder. or other impurities from entering the interior contact area of the circuit board socket 10. See FIG. 4.  
  Following curing of plug 36. the socket 10 may be inserted within a circuit board hole 42 of circuit board 44 and wave soldered to form a soldered electrical connection 46 between the body 10. and arms 26. and printed circuitry 48 on circuit board 44. Prior to wave soldering. the circuit board with the socket mounted therein is conventionally moved through a fluxing bath to improve soldering. The plug 36 prevents any flux or molten solder which could possibly flow into the open end of mouth 16 from flowing into the interior of the body 10. In this way. flux and solder. together with other impurities. are prevented from entering the contact area between arms 20. Silicone rubber plug 36 is not injured by the flux or the molten solder.  
  After completion of the soldering operation. a lead 50 may be inserted into the socket through mouth 16 and plug 36 as illustrated in FIG. 4. The silicone rubber is easily ruptured by the lead end of the pin. The rubber does not adhere to the surfaces of the contact spring arms 20. During insertion. the end of the lead removes any rubber from the area of contact with spring arms 20. As illustrated in FIG. 5, the lead 50 may break tip 40 into two portions.  
  The rubber plug 36 surrounds and forms an impurity resistant seal against the lead 50 inserted into the socket. In this way socket failure is reduced because impurities are sealed away from the contacts between the lead and the socket. When the lead is withdrawn the resiliency of the plug closes the opening formed by the lead and maintains an effective seal.  
  The exact shape of the plug 36 formed in opening 16 depends upon the amount of liquid rubber applied to the opening. Thus. in a case that a greater amount of rubber is applied. it is possible that the plug would overflow the opening and engage curls 24 and the exterior surfaces of body 12. Such variations in shape of the plug do not effect the desired seal. so long as the plug does completely close the lead-receiving opening 16.  
  While the invention has been described in connection with a specific form of circuit board socket. it is not intended to be limited to circuit board sockets of the specific type disclosed herein. Obviously. sealing plugs may be applied to openings in other types of circuit board sockets. whether or not leads are inserted through such openings.  
  While I have illustrated and described a preferred embodiment of my invention. it is understood that this is capable of modification. and I therefore do not wish to be limited to the precise details set forth. but desire to avail myself of such changes and alterations as fall within the purview of the following claims.  
 What I claim as my invention is:  
  1. An improved circuit board socket of they type adapted to be positioned within a circuit board hole and subsequently soldered to printed circuitry on the board. the socket including a hollow metal body. a mouth in the body communicating with the interior of the body. spring contact means within the body located to engage a lead inserted into the interior of the body through said mouth, means for tightly sealing said mouth comprising a portion of liquid viscous material flowed into said mouth and cured within the mouth to form a solid sealing plug, said means completely closing at least one section extending across the mouth. and an adherent connection between said means and the body at the mouth.  
  2. A circuit board socket as in claim 1 wherein said means comprises a plug of silicone rubber.  
  3. An improved circuit board socket as in claim 2 wherein said socket includes a spring member extending from the interior of the socket outwardly through said mouth and said plug completely surrounds said member.  
  4. An improved circuit board socket as in claim 3 including an adherent connection between said plug and the interior circumference of said mouth and a nonadherent connection between said plug and said memher.  
  5. An improved circuit board socket of the type adapted to be positioned within circuit board hole and subsequently soldered to a printed circuity on the board. the socket including a hollow metal body. an opening in the body communicating with the interiorof the body. spring contact means within the body. a penetrable resilient seal closing said opening without substantial stresses normal to the interior surface of the body. and an adherent connection between said seal and body.  
  6. An improved circuit board socket of the type adapted to be positioned in a circuit board hole and subsequently soldered to printed circuitry on the board. the socket including an elongate hollow metal body closed at one end and having a mouth communi- &#39;cating with the interior of the body at the other end: a spring contact comprising a U-shaped strip of spring metal confined within the interior of the body with the bight portion of the spring contact located adjacent the closed end of the body and with the arms of the spring contact&#39;extending from the bight portion toward the mouth of the body. contacts on the armslocated adjacent the bight portion and bowed toward each other to engage a lead inserted through the mouth and between the arms&#34;. a flux and molten solder sealing plug compris ing a portion of liquid viscous material flowed into said 1 mouth and cured within the mouth to form a solid sealing plug intimately conforming to the interior configuration of the socket at the mouth. said sealing plug completely closing at least one section extending across the mouth so as to seal the opening at the mouth against flux and molten solder while permitting insertion of a lead through the mouth and between the arms to engage said contacts; and an adherent connection 10. An improved circuit board socket as in claim 6. wherein said spring contact extends throughsaid plug and projects outwardly of the mouth with said plug completely surrounding a portion of the spring contact.  
 11. An improved circuit board socket as in claim 10 6 wherein said plug includes a tip located between the arms of the spring contact and spaced from the interior surface of the body; said plug engaging saidarms in non-adherent contact.  
 12. An improved circuit board socket as in claim 6 wherein the plug includes a tip located adjacentsaid contacts and spaced from the interior surface of the body.  
  13. An improved circuit board socket as in claim 12 wherein said plug is formed of silicone rubber.  
  14. An improved circuit board socket of the type adapted to be positioned in a circuit board hole and subsequently soldered to printed circuitry on the board. the socket including an elongate hollow metal body closed at one end and having a mouthcommunieating with the interior of the body at the other end. a 1  
 spring contact comprising a pair of opposed spring arms formed of flat metal stock located within the body and extending along opposed interior body walls. a connecting portion joining the ends of the spring arms at the closed end of the body and contacts on the arms bowed toward each other to engage a leadinserted through the mouth and between the arms; and sealing means comprising a portion ofliquid viscous material flowed into said mouth and cured within the mouth to form a solid sealing plug intimately conforming to the interior configuration of the socket at the mouth to completely seal the mouth to flux and molten solder.  
  15. An improved circuit board socket as in claim 14, including an adherent connection between said means and the interior surface of the mouth.