Electrical connector assembly

A board-to-board electrical connector assembly consists of a plug connector connected to a daughter board and a receptacle connector connected to a mother board. The receptacle connector has a first housing with a top face connected to the mother board and a bottom face connected to the plug connector, a pair of metal shields mounted to a front and rear face of the first housing, respectively, and a number of contacts fixedly received in contact passageways of the first housing. Each metal shield is integrally formed with two lateral sections each including an upper solder pad soldered to a grounding circuit of the mother board, and a leg covering a corresponding lateral wall of the first housing and defining an engaging foot. The plug connector has a second housing, a number of contacts fixedly received in contact passageways of the second housing and two second solder pads fixed to lateral ends of the second housing. The second solder pads are soldered to a grounding circuit of the daughter board and connect with the engaging feet of the shields.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to an electrical connector assembly, and 
particularly to an electrical connector assembly for directly connecting 
two printed circuit boards together which has an improved electromagnetic 
inferference/radio frequency interference (EMI/RFI) protection. 
2. The Prior Art 
A board-to-board connector assembly is used for directly connecting a 
daughter board to a mother board, without the necessity of using an 
auxiliary device such as a cable. 
FIGS. 6 and 7 show a conventional board-to-board connector assembly 
including a receptacle connector 1 and a plug connector 2. The receptacle 
connector 1 consists of a dielectric housing 11, a number of contacts 14 
(only one shown), a pair of shields 12 and a pair of solder pads 13. The 
housing 11 is formed to have a generally rectangular configuration with a 
bottom face 18 for proximity to the plug connector 2, a top face 19 for 
proximity to a mother board (not shown), a channel 111 exposed to the 
bottom face 18, a number of contact passageways 112 beside the channel 
111, a pair of solder pad mounting ears 15 projecting laterally near the 
top face 19 and each defining a solder pad receiving recess 151 fixedly 
receiving a corresponding solder pad 13, and a number of shield mounting 
blocks 113 on a front and rear side (not labeled) of the housing 11 near 
the bottom face 18. Each shield 12 is configured to have a number of 
alternating engaging tabs 121 and lugs 122 near a lower edge thereof. Each 
engaging tab 121 is interferentially engaged between two corresponding 
shield mounting blocks 113. Each lug 122 has a bead 123 projecting toward 
the housing 11. Each shield 12 further forms a number of fingers 124 at an 
upper edge thereof projecting into corresponding contact passageways 112 
to connect with corresponding contacts 14 connecting with a grounding 
circuit of the mother board. The solder pads 13 are soldered to the mother 
board to enhance the fastening of the receptacle connector 1 to the mother 
board. 
The plug connector 2 consists of an elongate dielectric housing 21, two 
solder pads 24, a number of contacts 22 and a number of auxiliary contacts 
214. The housing 21 is formed with an outer wall 210 defining a number of 
auxiliary contact passageways 213, a central ridge 211 located within the 
outer wall 210, and two solder pad mounting ears 23 at lateral ends of the 
housing 21 fixedly receiving the two solder pads 24, respectively. The 
central ridge 211 defines two rows of contact passageways 212 in a front 
and rear face (not labeled) thereof, respectively. The contacts 22 are 
fixedly received in the contact passageways 212, and the auxiliary 
contacts 214 are fixedly received in the auxiliary contact passageways 
213. Furthermore, each auxiliary contact 214 has a portion contacting a 
corresponding contact 22 connecting with a grounding circuit of a daughter 
board (not shown). The solder pads 24 are soldered to the daughter board 
to enhance the fastening of the plug connector 2 to the daughter board. 
When the receptacle and plug connectors 1, 2 are assembled, the central 
ridge 211 extends into the channel 111 so that the contacts 22, 14 of the 
plug and receptacle connectors 1, 2 are electrically connected together. 
The beads 123 on the lugs 122 of the shields 12 of the receptacle 
connector 1 extend into the corresponding auxiliary contact passageways 
213 to contact with the corresponding auxiliary contacts 214 of the plug 
connector 2, whereby the connector assembly can be protected from EMI/RFI 
by the shields 12. 
However, such a conventional board-to-board connector assembly does not 
shield two lateral ends of the housing 11 of the receptacle connector 1, 
which results in incomplete protection of the assembly from EMI/RFI. 
Furthermore, the connector assembly requires many components which 
increases manufacturing costs. Finally, the grounding circuit of the 
daughter board is only connected to the grounding circuit of the mother 
board via the connection between the auxiliary contacts 214 and the beads 
123. Such a connection is inadequate to ensure a reliable transmission of 
noise received by the plug connector 2 to the grounding circuit of the 
mother board. 
Hence, an improved board-to-board connector assembly is needed to eliminate 
the above mentioned defects of the conventional board-to-board connector 
assembly. 
SUMMARY OF THE INVENTION 
Accordingly, an objective of the present invention is to provide a 
board-to-board connector assembly which can be completely protected from 
EMI/RFI. 
Another objective of the present invention is to provide a board-to-board 
connector assembly requiring fewer components, resulting in a lower 
manufacturing cost. 
A further objective of the present invention is to provide a board-to-board 
connector assembly which reliably transmits noise received by the plug 
connector to the grounding circuit of the mother board. 
To fulfill the above mentioned objectives, according to one embodiment of 
the present invention, a board-to-board connector assembly includes a 
receptacle connector connected to a mother board and a plug connector 
connected to a daughter board. The receptacle connector comprises a first 
dielectric rectangular housing having a top face connected to the mother 
board, a bottom face opposite the top face, a front face, a rear face and 
two lateral walls between the bottom and top faces, a channel in the 
bottom face and a number of first contact passageways beside the channel 
and defined from the bottom face to the top face. A number of first 
contacts are fixedly received in the first contact passageways each having 
a tail portion soldered to the mother board. A pair of shields are fixed 
to the front and rear faces of the first housing. Each shield is 
integrally formed with a pair of lateral sections each having an upper 
solder pad soldered to a grounding circuit of the mother board and a leg 
covering a corresponding lateral wall of the first housing. Each shield 
further forms a number of lugs on a lower edge thereof and a number of 
fingers on an upper edge thereof. Each lug forms a bead projecting toward 
the first housing. The fingers extend into some of the first contact 
passageways to connect with some of the first contacts which are soldered 
to the grounding circuit of the mother board. 
The plug connector comprises a second rectangular housing defining an outer 
wall and a ridge within the outer wall. The ridge extends into the channel 
of the first housing and defines a number of second contact passageways in 
a front and rear face thereof. A number of second contacts are received in 
the second contact passageways and electrically connect with the 
corresponding first contacts. Each second contact has a tail portion 
soldered to the daughter board. A number of auxiliary contacts are fixedly 
received in auxiliary contact passageways defined in the outer wall of the 
second housing and electrically connect with some of the second contacts 
which are soldered to a grounding circuit of the daughter board. A pair of 
solder pads are fixed to lateral ends of the second housing and soldered 
to the daughter board for electrically connecting with the grounding 
circuit thereof and the legs of the shields.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Reference will now be made in detail to the preferred embodiment of the 
present invention. 
Referring to FIGS. 1 to 3, a board-to-board electrical connector assembly 
in accordance with the present invention consists of a receptacle 
connector 3 and a plug connector 6. 
The receptacle connector 3 consists of a dielectric housing 30, a number of 
contacts 5 (only one shown) and a pair of EMI/RFI shields 4. 
The housing 30 has a rectangular configuration with a bottom face 31 for 
proximity to the plug connector 6, a top face 32 for proximity to a mother 
board 80 (FIG. 4), a channel 35 exposed to the bottom face 31, a number of 
contact passageways 300 located beside the channel 35 and defined from the 
bottom face 31 to the top face 32, and two lateral walls 34. Each lateral 
wall 34 defines a depression 37 respectively in a front and rear face 
thereof. A seat 371 is formed by a corresponding lateral wall 34 in a 
corresponding depression 37. A number of mounting blocks 36 are formed on 
a front face and a rear face (not labeled) of the housing 30 adjacent to 
the bottom face 31. 
Each contact 5 includes a tail portion 50 for being soldered to the mother 
board and a contact portion 51 for electrically connecting with the plug 
connector 6. 
Each shield 4 is formed by stamping a metal sheet to have a rectangular 
body portion 40 having an upper edge formed with a number of fingers 45 
bent toward the housing 30, and a lower edge formed with a number of 
alternating engaging tabs 41 and lugs 42. Each lug 42 has a bead 421 
protruding toward the housing 30. Two lateral sections 44 are formed 
connecting with an upper part of two lateral ends of the body portion 40. 
Each lateral section 44 includes an upper solder pad 441 and a lateral leg 
442. Each lateral leg 442 forms an engaging foot 443 at a bottom thereof. 
Two recesses 43 are defined between the lateral sections 44 and the body 
portion 40 of each of the shields 4. 
To assemble the receptacle connector 3, particularly referring to FIG. 2, 
the contacts 5 are fixedly received in the housing 30 by inserting the 
contact portions 51 thereof in the corresponding contact passageways 300 
to reach a position where the tail portions 50 thereof are substantially 
flush with the top face 32. The shields 4 are then respectively mounted to 
the front and rear faces of the housing 30 by interferentially fitting 
each engaging tab 41 between two corresponding mounting blocks 36 whereby 
the recesses 43 fittingly receive the seats 371 of the lateral walls 34 of 
the housing 30 and the fingers 45 extend into corresponding contact 
passageways 300 to electrically connect with corresponding contacts 5 to 
be soldered to a grounding circuit of the mother board on which the 
receptacle connector 3 is mounted. Afterward, the solder pads 441 are bent 
along dotted lines 4412 (FIG. 1) to be perpendicular to the body portions 
40 of the shields 4 and flush with and beside the top face 32 of the 
housing 30. The legs 442 are bent along dotted lines 4422 (FIG. 1) to be 
perpendicular to the body portions 40 and cover the lateral walls 34 of 
the housing 30, whereby the assembly of the receptacle connector 3 is 
complete. The bent solder pads 441 are soldered to the mother board to 
enhance the fastening of the receptacle connector 3 thereto and to 
electrically connect with the grounding circuit of the mother board. Each 
engaging foot 443 projects from a corresponding leg 442 in a direction 
away from a corresponding side wall 34 of the housing 30. 
Particularly referring to FIG. 3, the plug connector 6 in accordance with 
the present invention has a structure substantially the same as the 
conventional plug connector 2 of FIG. 6. 
The plug connector 6 consists of an elongate dielectric housing 60, two 
solder pads 7, a number of contacts 8 and a number of auxiliary contacts 
66. The housing 60 is formed with an outer wall 610 defining a number of 
auxiliary contact passageways 65, a central ridge 61 located within the 
outer wall 610, and two solder pad mounting ears 64 at lateral ends of the 
housing 60 fixedly receiving the two solder pads 7, respectively. The 
central ridge 61 defines two rows of contact passageways 63 in a front 
face and a rear face (not labeled) thereof, respectively, for fixedly 
receiving the contacts 8 therein. The auxiliary contacts 66 are fixedly 
received in the auxiliary contact passageways 65 and each have a portion 
contacting with a corresponding contact 8 connected with a grounding 
circuit of a daughter board 82 on which the plug connector 6 is mounted. 
The solder pads 7 are soldered to the daughter board to enhance the 
fastening of the plug connector 6 to the daughter board and to 
electrically connect with the grounding circuit of the daughter board. 
Referring to FIGS. 4 and 5, when the plug and receptacle connectors 3, 6 
are assembled, the beads 421 extend into the auxiliary contact passageway 
65 to connect with the auxiliary contacts 66, respectively, and the 
engaging feet 443 of the legs 442 of the shields 4 of the receptacle 
connector 3 engage with the solder pads 7 of the plug connector 6, 
respectively. 
In the present invention, the solder pads 441 of the receptacle connector 3 
are integrally formed with the shields 4; thus, the present invention can 
reduce the number of components constituting the receptacle connector 3 
thereby reducing the manufacturing cost thereof. Furthermore, the side 
walls 34 of the housing 30 of the receptacle connector 3 are covered by 
the legs 442 of the shields 4; thus, the connector assembly in accordance 
with the present invention has a better protection from EMI/RFI than the 
conventional connector assembly. Finally and most significantly, in 
addition to the conventional connection achieved by the beads 421 and the 
auxiliary contacts 66 of the present invention, noise received by the plug 
connector 6 is transmitted to the grounding circuit of the mother board 
via the connection between the solder pads 7 and the engaging feet 443 of 
the legs 442 of the shields 4, whereby a reliable transmission of noise 
received by the plug connector 6 to ground is ensured. 
While the present invention has been described with reference to a specific 
embodiment, the description is illustrative of the invention and is not to 
be construed as limiting the invention. Various modifications to the 
present invention can be made to the preferred embodiment by those skilled 
in the art without departing from the true spirit and scope of the 
invention as defined by the appended claims.