METHOD AND MASS TERMINATION CONNECTOR WITH SOLDER CONNECTIONS

Abstract: A multiconductor electrical cable termination (10) for flat ribbon cable (11) has plural electrical contacts (26) pierced through the cable inslulation to engagement with respective conductors (13). The junctions of contacts and conductors are encapsulated in a base (15) that forms an integral structure with the contacts and cable maintaining the junctions substantially free of oxygen and moisture. Plural openings in the base provide access to terminal portions of the contacts for test probing thereof, or the like, while the contacting portions (12) of the contacts (26) are connected to another termination, connector or the like. The cable termination assembly is formed using both an insulation displacement mass termination connection of the contacts (26) and cable conductors and additionally has a solder connection (42) provided between respective contacts and cable conductors, for example during or after such encapsulation.

Description: METHOD AND MASS TERMINATION CONNECTOR WITH SOLDER CONNECTIONS BACKGROUND OF THE INVENTION The present invention is directed to a multiconductor electrical cable termination and, more particularly, to a relatively permanent termi¬ nation for a flat ribbon-like multiconductor electrical cable with mass termination insulation displacement and solder connections for the contacts and cable conductors. Since individual manual connection of each conductor in a multiconductor electrical cable, which usually has more than three con¬ ductors and as many as fifty or more conductors therein, would be a difficult and tedious task, a number of specialized connectors have been developed for simultaneously connecting each of the plural conductors to those of another multiconductor electrical cable via another connector, for example, to a plural signal input terminal of a computer or the like, to conductive paths on a printed circuit board or the like, etc. Typically these specialized connectors include multiple housing parts between which the cable is clamped, and usually before or during that clamping the multiple contacts of the connector puncture the electrical insulation of the cable to connect with respective conductors therein. The housing parts are mechani¬ cally secured in clamping engagement with the cable, and strain relief is usually provided by the clamping strength and/or by the terminal parts of the contacts pierced through the cable insulation. In U.S. Patent 4,030,799 is disclosed a multiconductor electrical cable termination formed as an integral structural combination of the multiconductor electrical cable, the plurality of electrical contacts, and a housing part that is molded about at least a portion of each of the contacts and a portion of the cable. Each contact forms a junction with a respective conductor of the cable, and the integral housing part is molded under elevated temperature and pressure conditions so that each of the junctions is substantially fully encapsulated by at least one of the cable insulation and the molded body part and, thus, maintained relatively free of moisture and SUBSTITUTE SHEE oxygen. The contacts and the conductors, therefore, may be of dissimilar metals, which will not corrode, oxidize or undergo any electrolysis-like activity due to the lack of moisture or oxygen at the junctions. Further¬ more, the molded housing part preferably is of a material compatible with that of the electrical insulation of the cable so as to bond chemically therewith to provide an effective strain relief for the termination and also to insure the integrity of the encapsulation of the junctions. The terminal portion of each electrical contact preferably extends fully through the cable insulation, and openings provided in the molded housing part offer access to the ends of those terminal portions for test probing thereof. It will be appreciated that the contacting portion of each electrical contact, Le. the portion being intended for electrical connection to a device other than the cable of the termination, may be of various designs for connection, for example, with pin contacts, female contacts, e.g. fork contacts, conductive paths on a printed circuit board, etc. Such cable termination may be formed using a mass termination technique known as insulation displacement connection (IDC) whereby the contacts, preferably a plurality of them simultaneously, pierce the cable insulation to engage cable conductors before the integral housing body part is molded. Such IDC mass termination approach is relatively inexpensive and expeditious. BRIEF SUMMARY OF THE INVENTION According to the invention, a solder connection of the contacts of the cable termination and the conductors of the cable being terminated is provided while also retaining the manufacturing and cost efficiency charac¬ teristics of a mass termination IDC connector device. A solder connection can provide added integrity of the junction of the contact and cable conductor while also assuring a minimum of impedance at such junctions. The solder connection preferably is formed using induction heating of the otherwise complete connector/cable termination to re-flow solder. Such solder connection is provided by employing contacts that have been pre-coated, e.g. by electro-plating, with a solder material at the IDC part thereof and after the IDC connection of the contacts and cable conductors has been made providing heat to the solder material to re-flow the same thereby forming a solder connection with respective cable conductors. Preferably the solder connection is so formed after the integral housing part has been molded about the IDC connection of the contacts and cable conductors by applying suitable source of heating energy to re-flow the solder. Advantages of the aforesaid approach include maintaining the solder connection area clean from contaminant and the confining of the solder to assure re-flowing in the correct areas of the contacts and especially the conductors while minimizing the amount of solder required for the purpose. Another important advantage is the avoiding of a spurious short circuit between an incorrect contact and cable conductor because during the soldering operation the individual contact and conductor pairs are isolated from the other such pairs by the molded housing part and the cable insulation. On the other hand, if desired, it is possible that the solder connections may be formed by applying heat and re-flowing the solder on the contacts prior to the molding step or possibly during the molding step. With the foregoing in mind, it is a primary object of the invention to provide a multiconductor electrical cable termination improved in the noted respects. Another object is to provide advantages of a mass termination multiconductor cable termination while also achieving the integrity and other characteristics of a solder connection junction. Another object is to achieve both the mass termination IDC cable termination cost and manufacturing efficiencies and to utilize the same to facilitate making solder connections in a multiconductor cable termination device. Another object is to facilitate the formation of plural solder connections of a mass termination cable termination device especially using induction heating, and, further, especially by effecting such induction heating and re-flowing of the solder material to form the solder connections after the cable termination device is otherwise already complete or substantially complete in manufacturing. SUBSTITUTE Si.∑εT Another object is to maintain the junctions between the termi¬ nals and conductors of a multiconductor electrical cable termination sub¬ stantially free of moisture and oxygen. An additional object of the invention is to provide integral molded strain relief for a multiconductor electrical cable termination. A further object of the invention is to provide for test probing or the like of the electrical circuits in a multiconductor electrical cable termination and especially to provide such ability while the termination is connected to another device. Still another object of the invention is to provide for the termination of a multiconductor electrical cable having a plurality of closely positioned, electrically insulated conductors. Still an additional object of the invention is to terminate in a facile manner a multiconductor electrical cable and especially a flat, ribbon-like multiconductor electrical cable. These and other objects and advantages of the present invention will become more apparent as the following description proceeds. To the accomplishment of the foregoing and related ends, the invention, then, comprises the features hereinafter fully described and particularly pointed out in the claims, the following description and the annexed drawing setting forth in detail a certain illustrative embodiment of the invention, this being indicative, however, of but one of the various ways in which the principles of the invention may be employed. BRIEF DESCRIPTION OF THE DRAWING In the annexed drawing: Fig. 1 is an exploded isometric view of the multiconductor electrical cable termination in accordance with the invention; Fig. 2 is a bottom view of the molded housing part of the multiconductor electrical cable termination looking in the direction of the arrows 2-2 of Fig. 1; Fig. 3 is an end elevation view of the multiconductor electrical cable termination looking in the direction of the arrows 3-3 of Fig. 1; Fig. 4 is a partial section view at two relatively spaced apart SUBSTITUTE SHE-TT generally vertical planes of the multiconductor electrical cable termination looking in the direction of the stepped arrows 4-4 of Fig. 1; Fig. 5 is a partial section view at a test probe opening of the multiconductor electrical cable termination looking in the direction of the arrows 5-5 of Fig. 4; Fig. 6 is an end elevational section view of the housing cover of the multiconductor electrical cable termination looking in the direction of the arrows 6-6 of Fig. 1; Fig. 7 is a partial side elevation view, mostly in section, of the housing cover looking in the direction of the arrows 7-7 of Fig. 6; Fig. 8 is an enlarged plan view of a contact plated with solder according to the present invention; Fig. 9 is an enlarged section view similar to Fig. 4 showing the solder connection of a typical contact and conductor in a multiconductor cable termination according to the present invention; and Fig. 10 is a schematic view of an induction heating method and apparatus in accordance with the present invention employed to effect completion of solder connections in the cable termination assembly by re- flowing solder upon application of induction heating. DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now more specifically to the drawing, wherein like reference numerals designate like parts in the several figures, and initially to Figs. 1 through 5, a multiconductor electrical cable termination is generally indicated at 10. The fundamental parts of the termination 10 include a multiconductor electrical cable 11, a plurality of electrical contacts 12 for connection at respective junctions to the respective conduc¬ tors 13 of the cable, and a housing 14 having a base body part 15 molded about at least a portion of each of the contacts and a portion of the cable to an integral structure therewith. In the illustrated preferred embodiment of the invention the housing 14 also includes a cover 16 adapted to fit onto the base 15 at a peripheral step 17 of the latter for appropriate containment of the contact¬ ing portions 18 of the electrical contacts 12; however, it will be appreciated SUBSTITUTE SHEET that the form of the cover 16 and its possible elimination will depend on the particular style of the contacting portions 18. For example, if the contacting portions 18 were simply points to be soldered in plated through openings of a printed circuit board or the like rather than of the illustrated fork-like style, the cover 16 can be eliminated from the termination 10. ' Preferably, the composition of the material of which the base 15 is formed and the composition of the electrical insulation 19, which maintains the conductors 13 in parallel spaced-apart locations, are similar or compatible so that when the base 15 is molded it will chemically bond to the insulation 19 further to increase the integrity of the structure of the termination 10 and at the same time to provide a molded strain relief that precludes separation of the contact terminal portions 20 from their respec¬ tive junctions 21 with the conductors 13, which are seen most clearly in Fig. 4. As shown in Fig. 4, the junctions 21 are encapsulated by the insulation 19 and the molded body of the base 15, and in the preferred form of the invention the body 15 is molded about portions of the electrical contacts 12 and cable 11 under the elevated temperatures and pressures used in an injecting molding machine, whereby any moisture and/or oxygen at the junction 21 is substantially eliminated during the molding process. There¬ fore, the material of which the electrical contacts 12 are formed and the material of which the conductors 13 are formed may be dissimilar without encountering corrosion, oxidation or electrolysis-like activity at the junctions 21, which will remain effective electrical connections between the electrical contacts and the respective conductors regardless of the external environment to which the termination 10 is subsequently subjected. More¬ over, since the base material and the insulation material chemically bond during molding of the base, the integrity of the encapsulation at each junction is further enhanced. Therefore, the relatively expensive copper or plated conductors 13 may be effectively terminated, for example, by less expensive aluminum electrical contacts 12. The terminal portion 20 of each electrical contact 12 preferably includes a pair of elongate prong-like arms 22 commonly supported from a TE SHEET base portion 23 and defining a relatively narrow slot 24 therebetween. The ends of the arms 22 remote from the base portion 23 preferably are tapered or chamfered to define an entranceway into the narrow slot 24 and to form generally pointed tips 25 to pierce easily through the cable insulation 19. The width of the narrow slot 24 is preferably narrower than the normal diameter of the conductor 13. Therefore, as a typical electrical contact 12 is joined with the cable 11 by urging the two toward each other, the pointed tips 25 pierce through the insulation 19 while the wide chamfered entrance¬ way guides the conductor 13 into the narrow slot 24. As the conductor 13 enters the slot, it is somewhat flattened to provide a relatively enlarged surface area of engagement or connection with the two arms 22. To maximize the efficiency of the insulation displacement- connections (IDC) a plurality of the conductors and contacts make con¬ nections simultaneously, for example, by loading the contacts into a holder and pressing the same simultaneously through the cable insulation into the aforenoted engagement with respective cable conductors. Such simul¬ taneous mass termination of respective cable conductors is extremely cost and time efficient. With the contacts in place in the cable, the base body 15 is molded about part of the contacts, cable conductors and cable insulation forming an integral structure therewith, for example, using a plastic injection molding machine. Although such molded plastic fills a large portion of any voids formed in the area of slot 24 of the respective contacts, at least small open areas remain exposed without molded plastic there, and this is especially true at areas of the contact directly engaged with and very proximate to the cable conductor 13. Moreover, preferably the cable conductor 13 is a stranded conductor, for example a seven strand conductor. A stranded conductor has good signal carrying properties and also is easily distorted to make a good connection with the edges of the contact 12 on opposite sides of the slot 24. An added advantage of the stranded conductor used in the present invention is that the spaces between the strands generally do not fill with plastic during the plastic molding step mentioned above; therefore, such spaces or areas are available for the flowing of solder SUBSTITUTE SHEET therein during the soldering process described further below. Furthermore, during the insulation piercing by the contact arms 22 and tips 25 (the insulation displacement step in the process of manufacturing the con¬ nector/cable termination 10 of the invention), the cable insulation may wipe closely against the surface of the contact and remain at least in part about the conductor 13, such as over part of the latter which is within the slot 24, and, thus, such insulation may further shield part of the cable and contact from plastic being molded directly into engagement therewith in order to provide space for solder to be re-flowed in forming a solder connection between respective contacts and cable conductors. The terminal portion 20 of each electrical contact 12 is in the same plane and is offset with respect to the contacting portion 18 thereof, as can be seen most clearly in Figs. 1 and 4. As seen particularly in Fig. 1, the electrical contacts 12 in the forward row 26 have their terminal portions offset to the left with respect to their contacting portions, and the electrical contacts in the rearward row 27 have their terminal portions offset to the right with respect to the contacting portions. This offset configuration of the electrical contacts 12 allows them to be of reasonable size and strength while the contacting portion of each contact in one row is directly aligned with the contacting portion of an opposite contact in the other row and with each of the relatively closely positioned parallel conductors 13 being connected to only a single respective contact 12. It will be appreciated that although the illustrated invention utilizes two rows of contacts, the principles of the invention may be, of course, employed in terminations having one row or more than two such rows of contacts or any other arrangement thereof. Each of the contact terminal arms 22 is preferably sufficiently long to extend fully through the cable 11 with a portion, for example, including the pointed ends 25, being exposed beyond the plane of the cable, as is illustrated most clearly in Figs. 3 and 4. When the base body 15, then, is molded about portions of the contacts and cable, openings or holes 28, which are seen most clearly in Figs. 2 through 5, are formed in the base to allow those portions of the arms 22 to remain exposed. Therefore, when the STITUTE SHEET multiconductor electrical cable termination 10 is connected, for example, to another connector, to a computer, to a printed circuit board or the like, with the conductors 13 operatively carrying respective electrical signals, each of the circuits in which the respective conductors 13 are connected may be tested, for example, by insertion of a probe from a test instrument or the like in the respective openings 28 to engagement with the exposed arms 22. Also, during the molding of the base body 15 ledges 29 are formed behind each of the arms 22 to prevent such an inserted probe from separating the arms and disturbing the sealed encapsulated and electrical integrity of the junction 21. As illustrated in Fig. 1, for example, each of the electrical contacts 12 is of the fork contact type whereby each of the contact portions 18 comprises a pair of generally parallel elongate arms 30 adapted for electrical and mechanical connection with a pin contact, for example, inserted therebetween. The housing cover 14, which is illustrated in Figs. 1, 6 and 7, preferably is also injection molded as a separate part of dielectric material such as, for example, plastic with chambers 31 therein for containment of the arms 30. The cover 16 has an outer wall 32 open at the bottom 33 to receive respective pairs of elongate contact arms 30 in the respective chambers 31, which are defined by the outer wall 32 and by internal walls 34, 35. In the cover top 36 are a plurality of apertures 37 for guiding respective pin contacts or the like into the respective chambers 30 between the two arms 30 of the respective electrical contacts 12 for mechanical and electrical engagement therewith. The opening at the cover bottom 33 is also stepped for joining at the step 17 of the base 15. In addition to the above express and implied advantages of the multiconductor electrical cable termination 10 of the present invention, the termination may be produced relatively more efficiently than the prior art clamping type specialized connectors previously used to terminate flat multiconductor ribbon-like cable, for example, by inserting the electrical contacts 12 in the cable 11 and molding the base body 15 of the housing 14 thereabout at the same work station of an injection molding machine substantially to complete the formation of the termination in a single step. Thereafter, if the housing 14 is to include a cover 16, the latter may be easily fitted to the base 15 at the step 17 and secured thereto, for example, by accoustical or ultrasonic welding techniques. Turning, now, to Fig. 8, a contact 12 employed in the present invention is shown in enlarged plan view. Preferably the arms 22 and part of the contact base 23 are electro-plated with a relatively copious amount of solder material 40, and, if desired, some flux material may be provided there as well. In the preferred embodiment flux is employed and may be applied directly to the contacts as part of or as a separate step as is the solder 40, for example. The flux is not separately identified in the drawings but may be construed as being part of the solder 40 that is shown. The solder 40 is shown about the outer edges and especially about the inner edges 41 of the arms 22 bounding the slot 24. If desired, the solder may be applied to the contact by means other than electro-plating and may be applied in a more restricted area than that shown in the drawings. The cable conductors 13 preferably are of the stranded type noted above and also are preferably formed of a material that will form a satisfactory solder connection with the solder and the contacts 12 with good reliability of the electrical connection so formed. In the preferred embodiment and best mode of the invention, the cable conductors 13 are formed of tinned copper material. According to the preferred embodiment and best mode, too, the solder 40 is re-flowed to form the solder connection 42 shown in Fig. 9 after the body 15 has been molded in plate and, if used, after the cover 16 has been put in place and preferably ultrasonically welded to the body 15. To effect such re-flowing of the solder, heat is applied to the solder. Such heat application may be by laser, heating in an oven, or other technique. For example, a laser may be focused into the opening 28 onto the exposed contact arms 22; and heat from the laser may be transmaitted through the metal of the contact to re-flow the solder thereon, especially in the area of the desired junction of the contact and cable conductor 13. Alternatively, if the material of which the body 15 and cover or cap 16 are comprised is of the thermosetting type or is capable after being molded of withstanding the temperature required to re-flow the solder, it is possible to place the connector 10 in an oven to heat the solder to re-flow the same without detrimentally affecting the body 15 or the cover 16. According to the preferred embodiment and best mode of the invention, as is illustrated in Fig. 10, induction heating is used to re-flow the solder 40. Specifically, a power supply 50 provides electrical power to an induction heating coil 51 via electrical leads 52, 53. The induction heating coil 51 is adequately large to receive the completed connector/cable termination 10 therewithin. Upon application of suitable electrical ener¬ gization to the coil 51 the same effects heating of the contacts within the connector 10 and/or of the solder 40 causing the latter to re-flow over at least part of the contacts and respective conductors associated therewith. The flowing solder 40 preferably makes a good solder connection 42 by flowing into the interstices between the strands of the cable conductor 13. Thus, such induction heating process facilitates further the manufacturing of the cable termination 10 according to the invention achieving both direct engagement and solder connection integrity of the individual junctions of respective contacts 12 and conductors 13. The use of induction heating, too, avoids the subjecting of the other part of the connector 10 to heat that may be otherwise disadvantageously affecting same, while also enabling com¬ pleting of all the or a plurality of the solder connections in the connector in a simultaneous manner. Thus, it will be appreciated that the present invention provides for the terminating of a multiconductor cable achieving the labor, cost, and time efficiency of a mass termination connector, especially of the IDC type while also adding the reliability of a solder connection. Moreover, due to the ability to effect the solder re-flowing within a confined area after molding of the body 15, such soldering step may be effected rapidly and efficiently, e.g. in terms of cost, labor, time, materials and equipment. Upon completing the formation and/or assembly of the multi¬ conductor electrical cable termination 10, it may be easily connected to another electrical connector, a plural signal input terminal of a computer, conductive paths on a printed circuit board, or the like to connect the conductors 13 in respective circuits. The contacts 12, although described as female contacts, may be of the male type or of other specialty type for connecting the conductors 13 with other respective circuits, conductors, etc. Moreover, while the invention is illustrated and described above with reference to multiconductor electrical cable termination 10 located at an end of the multiconductor electrical conductor 11, it will be apparent that such a termination also may be provided in accordance with the invention at a location on a multiconductor electrical cable intermediate the ends thereof. SUBSTITUTE SHEET

Claims: The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows: 1. A multiconductor electrical cable termination, comprising: a multiconductor electrical cable including a plurality of conductors and electrical insulation about said conductors maintaining the latter electrically insulated from each other, a plurality of electrical contacts, each including terminal means for connecting to at least one of said conductors forming a junction therewith and contacting means for electrically connecting to an external member placed to engagement therewith, a solder connection between respective contacts and conductors, and a housing including base means for holding said contacts and said cable in relatively fixed position, said base means comprising a body molded about at least a portion of each of said contacts and a portion of said cable, whereby said base means, said contacts and said cable form an integral structure. 2. A multiconductor electrical cable termination as set forth in claim 1, wherein each of said junctions is sealed in air-tight and relatively moisture-free and oxygen-free condition by at least one of said electrical insulation and said housing body. 3. A multiconductor electrical cable termination as set forth in claim 2, wherein said conductors and said electrical contacts are of dissimilar metals. 4. A multiconductor electrical cable termination as set forth in claim 2, wherein said multiconductor electrical cable comprises flat ribbon-like cable, and said housing body comprises a material that chemi¬ cally bonds with said electrical insulation during molding of said body. 5. A multiconductor electrical cable termination as set forth in claim 1, wherein said terminal means comprises piercing means for piercing said electrical insulation to engage a conductor therein. 6. A multiconductor electrical cable termination as set forth in claim 5, wherein said piercing means comprises prong-like arm means for deforming such engaged conductor to enlarge the surface area of said junction. EET 7. A multiconductor electrical cable termination as set forth in elaim 6, wherein at least one of said body and said electrical insulation fully encapsulate said junctions in fluid-tight relation. 8. A multiconductor electrical cable termination as set forth in elaim 1, wherein at least one of said body and said electrical insulation fully encapsulate said junctions and said body is molded under elevated temperature and pressure conditions whereby said encapsulated junctions are substantially free of moisture and oxygen. 9. A multiconductor electrical cable termination as set forth in claim 1, wherein said body comprises a material compatible with that of said electrical insulation to bond chemically with the lattr upon molding of said body under elevated temperatures and pressure conditions. 10. A multiconductor electrical cable termination as set forth in claim 1, wherein said terminal means of each electrical contact comprises at least one elongate arm of a sufficient length to extend on both sides of said electrical insulation, and said body comprises hole means for access to said elongate arms, whereby a test probe or the like can be inserted to electrical engagement with said elongate arms. 11. A multiconductor electrical cable termination as set forth in claim 10, wherein said terminal means comprises two elongate arms. 12. A multiconductor electrical cable termination as set forth in claim 11, wherein said multiconductor electrical cable comprises flat ribbon-like cable, and said terminal means comprises means for piercing said electrical insulation upon forcing one of said cable and said electrical contacts relatively together. 13. A multiconductor electrical cable termination as set forth in claim 1, wherein said housing further comprises cover means for contain¬ ment of said contacting means of said electrical contacts. 14. A multiconductor electrical cable termination as set forth in claim 1, wherein said contacting means comprise fork-like arms. 15. A multiconductor electrical cable termination as set forth in claim 1, wherein said multiconductor electrical cable comprises flat ribbon-like cable having more than three conductors therein. SUBSTITUTE SHEET 16. A multiconductor electrical cable termination as set forth in claim 15, wherein said terminal means and said contacting means of each electrical contact are linearly offset with respect to each other, whereby said contacts may be relatively closely positioned in plural rows in said body while respectively connecting with each of said closely positioned con¬ ductors. 17. A multiconductor electrical cable termination as set forth in claim 15, wherein said multiconductor electrical cable has from about twenty to about fifty conductors. 18. A method for making a cable termination comprising, inserting a contact having solder thereon through the insulation of an electrical cable so as to make electrical connection with a conductor in such cable placing at least some of such solder at least in proximity to such conductor, heating such solder to re-flow the same to form a solder connection with such contact and such conductor, and molding an electrically insulating body about at least part of such contact, solder junction, conductor and cable insulation to form an integral cable termination body. 19. The method of claim 18, wherein said molding step is carried out prior to said heating step. 20. The method of claim 19, wherein said heating step com¬ prises induction heating. 21. The method of claim 20, wherein said induction heating comprises placing such cable termination in an induction heating coil and energizing such coil to effect heating of at least one or more of such contact, conductor and solder. 22. The method of claim 20, wherein such cable comprises a multiconductor cable, such contact comprises a plurality of contacts for connection with respective conductors of such cable, and wherein such induction heating effects heating of a plurality of the junctions of such respective contacts and conductors to effect simultaneously the soldering of a plurality of such junctions.

Inventors: VENALECK HOWARD J, VENALECK JOHN T, VENALECK, HOWARD, J., VENALECK, JOHN, T.
Applicants: ASS ENTERPRISES INC, ASSOCIATED ENTERPRISES, INC.
Application year: 1986
Main classification: H01R4
IPC codes: H01R4, H01R43