WO2003073558A1

WO2003073558A1 - Electrical connector for printed circuit board

Info

Publication number: WO2003073558A1
Application number: PCT/US2003/004961
Authority: WO
Inventors: Atsuhito Noda; Yoshihiro Tetsuka
Original assignee: Molex Incorporated
Priority date: 2002-02-22
Filing date: 2003-02-21
Publication date: 2003-09-04
Also published as: JP4000865B2; JP2003257566A; AU2003211153A1; TW579086U; CN100517875C; CN1639922A

Abstract

An electrical connector (10) for mounting to a printed circuit board, comprises a dielectric housing (40) and a plurality of terminals (20) arranged side by side at the predetermined pitch. Each terminal (20) includes a flat base portion (21), a pair (24) of contact members formed from a continuous folded-back portion (23) that is folded back to one side of the flat base portion (21), and a carrier coupling section (30) that is bent at substantially right angle to the opposite side of the flat base portion (21). The housing (40) holds the terminals (20) by an over-molding of the housing around the flat base portions (21) of the terminals (20) to form a generally flat plate-like housing. The pair (24) of contact members of the terminal (20) extends toward one surface (40A) of the dielectric housing (40) and the carrier coupling section (30) extends toward the other surface (40B) of the housing (40).

Description

ELECTRICAL CONNECTOR FOR PRINTED CIRCUIT BOARD

Background of the Invention

The present invention relates generally electrical connectors suitable for mounting to a printed circuit board and, more particularly, to connectors used in solder ball grid array (BGA) applications. In the past, one such type of an electrical connector is known to include a dielectric housing and a plurality of terminals. FIGS. 6 and 7 show an example of such a prior art connector, and in particular, FIG. 6 shows one terminal 100 of the connector. A plurality of such terminals 100 are mounted or press-fitted to a housing 200 (FIG. 7) in order to complete an electrical connector 300. Although only one terminal 100 is shown in the figure, a plurality of such terminals 100 are actually arranged side by side at the predetermined pitch. Referring to

FIG. 6, the terminal 100 includes a pair of contact members, or arms 101, a press-fit portion 102 formed at the base of the contact members, and a fixing portion 103 formed adjacent the press-fit portion for connection to a solder ball 104. The terminal 100 is produced from a thin metal sheet by a stamping and forming process. The terminal 100 is received in a terminal receiving cavity (not shown) formed in the housing 200 so that the press-fit portion 102 is press-fit against the inner wall of the terminal receiving cavity to hold the terminal 100 in place. The solder ball 104 is soldered to the fixing portion 103 of the terminal 100 and a portion of the solder ball 104 opposite to the fixing portion 103 externally projects from the housing 200. hi FIG. 7, the mating connector 400 is shown to include a dielectric housing 600 having a plurality of contact pins 500 mounted therein, which pins 500 correspond to pars of contact members of the terminals 100 in the connector 300 with one-to-one relation. The connector 300 and the mating connector 400 form a connector assembly. In general, each of the connectors 300 and 400 is mounted to their respective printed circuit boards so that they may be connected to each other via the connectors 300 and 400. hi addition to the terminal receiving cavity, as described above, another means for holding the terminal in the dielectric housing has been known in the art in which a terminal mounting channel is formed through the housing and a side edge of the terminal is latched to an opposite inner wall of the terminal mounting channel (see Japanese Patent Laid-Open No. 11- 144821, for example).

These prior art connectors have a problem in that mounting of their terminals requires a number of assembly steps and thus adds cost to manufacturing because each terminals has to be press-fit to the terminal-receiving cavity or channel. In view of the recent tendency in electronics toward multi-pole configuration and higher terminal densities and with the advent of such design that not less than 100 terminals are arranged side by side at higher density, there is a strong need to solve the problem as above.

Furthermore, the prior art such terminal-receiving cavities or mounting channels formed in the housing create other problems such as when soldering the connector to the circuit board, wicking of either solder or solder flux may be produced via a clearance between the terminal and its cavity or channel, which may cause contamination to the contact members mated with the terminals of the mating connector.

In view of the above an object of the present invention is to provide an electrical connector having an improved configuration that reduces the manufacturing cost of the connector and eliminates the problem of solder or solder flux wicking.

Summary of the Invention;

To attain such object an electrical connector for mounting to a printed circuit board, comprising a dielectric housing and a plurality of terminals arranged side by side at the predetermined pitch, is improved according to the present invention in that: each of the terminals includes a flat base portion, a pair of contact members formed from a first continuous folded- back portion that is folded back onto one side of the flat base portion, and a second folded back section bent transverse to the base portion, but extending on the opposite side of the base portion; the housing holds the terminals by performing an over-molding of the housing around the flat base portions of the terminals to form a generally flat plate-like housing; and the pair of contact members of the terminal extends toward one surface of the housing and the carrier coupling section extends toward the other surface of the housing.

According to one embodiment of the present invention, the pair of contact members of each terminal is disposed in a recess formed in said one surface of the housing. According to another embodiment of the present invention, the other surface of the housing is provided with an opening leading to the terminal flat base portion, and the connector T U 03/04961

further includes solder balls soldered to the flat base portion via the openings and that externally project beyond the other surface of the housing.

According to further embodiment of the present invention, the terminal further includes a bent portion connecting between the flat base portion and the carrier coupling section, and a cut- out portion formed in the bent portion into which resin material that forms the housing, is permitted to flow, thereby anchoring the terminal base portion in place within the housing

According to another aspect of the present invention there is provided an electrical connector assembly, comprising: an electrical connector constructed in the manner as described above; and a mating connector comprising a plurality of contact pins each corresponding to each pair of contact members of the terminals with one-to-one relation, and a housing holding the contact pins by an over-molding of the housing around the contact pins to form a substantially flat plate-like housing.

According to one embodiment of the present invention one surface of the housing of the mating connector is provided with an opening leading to a base portion of the contact pin, and the mating connector further includes a solder ball soldered to the base portion via the opening and that is externally projected beyond said one surface of the housing.

An electrical connector according to the present invention is advantageous in the following points of view: Firstly, because of the configuration in which the housing is over- molded to the terminal consisting of the base portion, the pair of contact members and the carrier coupling section so that the terminal is held in the housing, there is no terminal press-fitting step required, and therefore, an efficient manufacturing process can be realized even for the electrical connector having an increased number of terminals. Furthermore, because of no clearance that extends through the housing between the housing and terminal, there is no possibility of any rising action of solder or solder flux occurred during the soldering operation on the printed circuit board.

Secondly, because the pair of contact members of the terminal are confined in a recess of the housing, the pair of contact members are protected by the housing against any deformation or contamination thereto.

Thirdly, because of the solder ball soldered to the base portion of the terminal and externally projected from the housing, a connector of ball grid array (BGA) type is provided.

Alternatively, a connector of pin grid array (PGA) type in which a pin-like solder tail for DIP soldering or a solder tail for surface soldering (SMT) may be provided on the carrier coupling section of the terminal may be provided within the scope of the present invention.

Fourthly, because of the presence of a bent portion between the base portion and the carrier coupling section, a cut-out portion is formed in the bent portion, which assists in reducing the distance (or pitch) between adjacent terminals of the connector as much as possible. This is very suitable for smaller pitch arrangement of the terminals.

Fifthly, because the mating connector also has the same configuration in which its own dielectric housing is over-molded to a number of contact pins, there is provided the electrical connector assembly having a capability of easily and efficiently mating the electrical connector with the mating connector. Such connector assembly eliminates any possibility of rising action of solder or solder flux during the process of mounting the connector to the circuit board.

Sixthly, the mating electrical connector may be an electrical connector of BGA type.

These and other objects, features and advantages of the present invention will be clearly understood through a consideration of the following detailed description.

Brief Description Of The Drawings h the course of this detailed description, the reference will be frequently made to the attached drawings in which:

FIG. 1 is a cross-sectional view partially illustrating an electrical connector assembly consisting of a connector and its mating connector according to one embodiment of the present invention and illustrating them in a connected state;

FIG. 2 is a perspective view of one of terminals of the connector assembly of FIG. 1;

FIG. 3 is an elevational view of the terminals of FIG. 2 coupled to a carrier strip;

FIG. 4 is a side view of the carrier strip of FIG. 3;

FIG. 5 is a perspective view of two terminals of FIG. 1, shown interconnected but with the supporting housing removed for clarity:

FIG. 6 is a perspective view of a prior art terminal; and,

FIG. 7 is an elevational view illustrating the prior art terminal of FIG. 6 in place within a connector and mated to a mating connector. Description of the Preferred Embodiment

Referring to FIG. 1, there is shown an electrical connector assembly consisting of a connector 10 and a mating electrical connector 50, both of which can be mated together. The connector 10 includes a plurality of terminals 20 arranged in side-by-side order at a predetermined pitch and a dielectric housing 40 is molded onto the terminals 20, preferably by over-molding. The mating connector 50 includes a plurality of contact pins 60 arranged in a side-by-side to correspond to the terminals 20 on the connector of the invention, also in a one-to- one relation, and a dielectric housing 80 is over-molded onto the contact pins 60. The terminals 20 and the contact pins 60 are arranged at the predetermined pitch in the right-to-left direction, as is shown in FIG. 1, and in addition, they are arranged in the direction perpendicular to the plane of the paper of FIG. 1.

Each of the terminals 20 of the connector 20 is produced by preferably stamping and forming it from thin sheet metal in the shape as shown in FIG. 2. In particular, the terminal 20 is produced to include a base portion 21 in the form of a flat rectangular plate, a continuous folded- back portion 23 that is folded back along one edge 22 of the base portion 21 on one side (upper side) thereof to have the width smaller than that of the base portion 21, and a pair 24 of contact members, or arms, that are partially formed as part of the folded-back portion 23. The pair 24 of contact members includes a first and second contact members, that take the form of upwardly projecting arms 25, 26. The one contact arm 25 may have a width that is slightly greater than the width of the other contact arm 26. The contact arms 25 and 26 are formed in such manner that a separation channel 27 is defined longitudinally in the continuous folded-back portion 23 to form a bifurcated contact portion, which is then bent at substantially a right angle to the plane of the base portion 21. The contact arms 25 and 26 include respective base pieces 27, 28 which extend in parallel with and above the base portion 21, (FIG. 2) and which have different lengths from each other so that the contact pin 60 can be received between the contact arms 25 and 26. Curved contact portions 25a and 26a are formed at the free ends of the contact arms 25 and 26. The contact portions 25a, 26a are resiliently deformed to separate slightly from each other when the contact pin 60 is received therebetween but do not completely separate so as to lose engagement with the contact pin 60.

The terminal base portions 21 are aligned with terminal-receiving cavities 40, 41 and preferably seal them off so as to define two separate, aligned sub-cavities, shown in FIG. 1 as being above and below the flat base portions 21 of the terminals 20. As shown in the drawings, the contact arms 25, 26 extend upwardly from the base portion 21 into the first sub-cavity, while the second sub-cavity receives a solder ball 33 therein.

The terminal 20 further can be seen to include a carrier strip coupling section 30 (FIG. 2) that also may be considered as a folded-back piece in that it is bent at substantially a right angle along an other edge 29 of the base 21 and extends toward the opposite (lower) side of the base portion 21. The carrier coupling section 30 has the same width as the base 21. A bent portion 31 is provided for connecting between the base 21 and the carrier strip coupling section 30, and an opening 32 is preferably formed in the bent portion 31. The housing 40 is preferably over-molded over the terminals 20 and serves to embed four sides, or edges of the terminal base portion 21 to form a generally flat plate-like housing, h this regard, the pair 24 of contact arms extend toward one housing surface 40A (the upper in FIG. 1), while the carrier strip coupling section 30 extends toward the opposite housing surface 40B. A recess is defined by the first sub-cavity 41 of the housing and opens to the housing upper surface 40A and it has a size and the depth suitable for receiving the pair of contact arms 24 so that they do not externally project from the housing 40. A similar, second sub-cavity 42 lead communicates with both the terminal base 21 and the second, or lower surface 40B of the housing 40. The carrier strip coupling section 30 may slightly project from the housing opposite surface 40B, as shown. A resin material for the housing 40 is injected into the cut-out portion 32 in the bent portion 31 connecting between the carrier coupling section 30 and the terminal base

21.

Each conductive terminal 20 is held at the predetermined positions due to the molding of the housing 40 over them, and a solder ball 33 is provided in the opening, or second sub-cavity 42, formed in the lower part of the housing 40. The solder ball 33 is soldered to the center area of the terminal base 21 that is exposed in the opening 42 and a portion of the solder ball 33 projects outwardly beyond the housing opposite surface 40B.

FIGS. 3 and 4 show a series of terminals 20 coupled to a carrier strip 34 at the time before the over-molding of the housing 40 onto the terminals. The carrier coupling sections 30 of the terminals 20 are coupled to the carrier strip 34 via frangible breaking portions 35. The over-molding of the housing 40 is preferably performed while the terminals 20 are still coupled to the carrier strip 34, and thereafter the carrier strip 34 is separated at the position of the breaking portions 35. Alternatively, the terminals 20 may be separated from the carrier 34 and set in their predetermined positions in the mold (not shown), and thereafter, the over-molding of the housing 40 may be performed. h the mating connector 50, an over-molding of the housing 80 is performed on the contact pins 60 so as to embed the middle portions thereof and to form a generally flat plate-like housing of the connector 10. The base 61 of the contact pin 60 faces an opening 81 formed in one surface 80A of the housing 80. A solder ball 62 is positioned in the opening 81. The solder ball 62 is soldered to the contact pin base 61 and a portion of the solder ball 62 is projects beyond the outer surface of the housing 80.

FIG. 5 is a view illustrating only the terminals 20, the contact pins 60 and the solder balls 33, 62 in such condition that the connectors 10, 50 are mated together.

As described above, because of the configuration of the connector 10 in which the housing 40 is over-molded to the terminals 20, there is no press-fitting step for the terminals 20 required, and therefore, an efficient manufacturing process can be realized even for the connector 10 with an increased number of terminals 20. Furthermore, because of the configuration in which the housing 40 is over-molded to the terminals 20, there is no clearance produced at the boundary between the terminals 20 and the housing 40. Therefore, there is no possibility of any rising action of solder or solder flux along the contact members occurred during the soldering operation in which the solder ball 33 is soldered to the base portion 21 of the terminal 20 and to the contact pad on the printed circuit board. This allows to keep the pair of the contact members clean and to avoid any loss in electrical connection.

The same is true for the mating connector 50. hi particular, because of the configuration in which the housing 80 is over-molded to the contact pins 60, there is no press-fitting step for the contact pins 60 required and there is no possibility of any rising action of solder or solder flux occurred during the soldering operation of the solder ball 62. Because of the configuration in which the pair 24 of terminal contact arms are confined in the recess 41 formed in the housing 40 without any portions thereof projecting externally, the pair 24 of the contact arms can be protected against any unintended contact by a hand or any foreign matter before mating with the mating connector 50. In other words, they can be protected against any deformation or contamination. Moreover, it is possible to avoid such condition that any electrostatic charge is discharged via the pair 24 of the contact members to the circuit on the board to damage some components in the circuit. The opening portion 32 formed in the bent portion 31 between the base 21 and the carrier coupling section 30 of the terminal 20 provides an advantageous effect in that any possibility of short circuiting between one edge 22 of one terminal 20 and the other edge 29 of the adjacent terminal 20 can be eliminated, and therefore, the distance (or the pitch) between the adjacent terminals 20 can be reduced to as small as possible. This is very effective for a small sized connector 10, and more particularly, for such connector that has an increased number of terminals 20. Because of a resin material flowed into the cut-out portion 32 for producing the housing 40, the higher integrity between the terminals 20 and the housing 40 is assured, which prevents any movement of the terminals 20. Because of the solder ball 33 soldered to the terminal 20 and partially projected from the housing 40, the connector 10 of BGA type where a multiplicity of terminals are arranged at higher density can be provided. The same is true for the mating connector 50. Alternatively, a connector having no such solder ball 33 may be provided, hi such case, the carrier coupling section 30 of the terminal 20 may be connected to a pin-like DIP solder tail externally projected from the housing 40 or to an SMT solder tail. Then the solder tail may be coupled to the carrier

34 via a breaking portion.

It is apparent from the foregoing that, because of the configuration of a connector in which a dielectric housing is over-molded to terminals arranged side by side at the predetermined pitch, there is no press-fitting step for the terminals required, and therefore, an efficient manufacturing process can be realized even for the connector having an increased number of terminals. Furthermore, because of no clearance produced at the boundary between the terminals and the housing, there is no possibility of any rising action of solder or solder flux occurred during the soldering operation, which allows to keep the pair of the contact arms clean and to avoid any loss in electrical connection.

Claims

CLAIMS:

1. A connector comprising: an insulative housing including a body portion with opposing first and second exterior surfaces, a plurality of terminal-receiving cavities formed in the housing body portion, each of the terminal-receiving cavities extending through said housing body portion to the housing opposing first and second surfaces; and, a plurality of conductive terminals disposed in said terminal-receiving cavities, a single one of the terminals being disposed in a single cavity, each of the terminals including: a terminal body portion extending horizontally within its associated terminal- receiving cavity, the terminal body portion having a plurality of distinct edges, first and second terminal retention members being disposed along first and second opposing edges of said body portion, and a contact portion that extends away from said terminal body portion, within the associated terminal-receiving cavity, the two terminal retention members being embedded in said housing to thereby hold said terminal body portion in place within said housing, said terminal first retention member including an extent folded back upon said terminal body portion along said terminal body portion first edge and said terminal second retention member including a retention stub disposed along said terminal body portion second opposing edge, the retention stub being formed by bending another extent of said terminal body portion at an angle to said terminal body portion, said retention stub further including an opening formed therein along said terminal body portion second edge, the opening being filled with material from which said housing is made and thereby providing a means for anchoring said terminal within said housing.

2. The connector of claim 1, wherein said contact portion includes a pair of contact arms spaced apart from each other, each of the contact arms including a curved contact head, the contact heads of said contact arms engaging an opposing connector terminal on opposite sides thereof. The connector of claim 1, wherein said terminal contact portion includes a slot disposed therein which defines a pair of contact arms, each of the contact arms having a free end spaced from said terminal base portion.

The connector of claim 2, wherein said contact arms do not project past a surface of said housing.

The connector of claim 3, wherein said contact arm free ends include curved contact faces.

The connector of claim 1, wherein said terminal-receiving cavities are closed off intermediate said housing opposing first and second surfaces by said terminal body portions.

The connector of claim 6, wherein said terminal body portions divide each terminal- receiving cavity into first and second sub-cavities, the first sub-cavity opening to said housing first surface and said second sub-cavity opening to said housing second surface.

The coimector of claim 7, wherein said second sub-cavity includes a solder ball disposed therein and in contact with said terminal body portion, the solder ball projecting out of said second sub-cavity past said housing second surface.

The connector of claim 1, wherein said second terminal retention member extends toward said housing second surface.

The connector of claim 9, where said second terminal retention member terminates in a stub end and said stub end protrudes past said housing second surface.

An electrical connector assembly for interconnecting together two circuit boards, the connector assembly comprising: first and second interengaged connector components; the first connector component including a first insulative connector housing having opposing first and second surfaces, a plurality of conductive contact pins disposed in the first connector housing and extending past the first connector second surface, said first connector housing further including a plurality of recesses disposed in said first connector housing second surface, the contact pins extending into the recesses, and solder balls disposed in said first connector housing second surface in contact with said contact pins and extending past said first connector housing second surface; and, the second connector component including a second insulative connector housing having opposing first and second exterior surfaces, a plurality of terminal-receiving cavities formed in the second connector housing, each of the terminal-receiving cavities extending completely through said second connector housing and communicating with said second connector housing first and second surfaces, a plurality of conductive terminals disposed in said terminal-receiving cavities, a single one of the terminals being disposed in a single cavity, each terminal including a body portion extending horizontally within its associated terminal-receiving cavity, the terminal body portion including first and second terminal retention members being disposed along first and second opposing edges of said terminal body portion, and a contact portion extending away from said terminal body portion within a portion of its associated terminal-receiving cavity, the two terminal retention members being embedded in said housing to thereby hold said terminal body portion in place within said second connector housing, said terminal first retention member including an extent folded back upon said terminal body portion along said terminal body portion first edge and said terminal second retention member including a retention stub disposed along said terminal body portion second opposing edge, the retention stub being formed by bending another extent of said terminal body portion at an angle to said terminal body portion, said second connector further including a plurality of solder balls disposed in said terminal-receiving cavities and extending past said second connector housing second surface.; and, said first connector contact pins extending into said second connector housing terminal-receiving cavities and being engaged with said second connector terminal contact portions when said first and second connector housings are mated together such that said solderballs are arranged on opposite sides thereof. The connector assembly of claim 11, wherein said second connector component terminal contact portions each include a pair of spaced-apart contact arms, each of the contact arms having an engagement surface disposed thereon for engaging opposing surfaces of said first connector component contact pins.

The connector assembly of claim 12, wherein said terminal base portions seal off said terminal-receiving cavities and further divide each of said cavities into first and second sub-cavities, said terminal contact portions extending into said first sub-cavities and having a length less than a depth of said first sub-cavities whereby, said contact arms do not extend past said second connector housing first surface.

The connector assembly of claim 11 , wherein a free end of said second retention member projects past said second connector housing second surface.

The connector assembly of claim 11 , wherein each of said second connector terminal retention stubs include an opening formed therein along said terminal body portion second edge, the opening being filled with material from which said second connector housing is made and thereby providing a means for anchoring said terminal within said second connector housing,