Connector holding device

A holding device (50) for securing two electrical articles (22,94) together includes a U-shaped leading end (52) having a pair of leg portions (54). The U-shaped end (52) and adjacent leg portions (60) define a spring means, adapted to be received in an aperture (96) of the second article (94). The legs (54) extend to free ends (70) and define a retaining section (73) adapted to be received into a recess (32) within a housing (24). The recess (32) includes a central wall portion (42) having leading engagement sites (44), which cooperate with inner leg edges (58) to secure the device (50) within the housing (24). Upon inserting the device (50) into the housing recess (32) and the U-shaped leading end (52) of the device (50) into the second article aperture (94), compressive engagement of interference projections of the spring means with aperture wall surfaces causes legs (60) of the U-shaped leading end (52) to be moved inwardly toward each other, and concomitantly therewith the leg sections (70) in the recess (32) to pivot about the leading engagement sites (44) to move barbs (72,74) thereon into tighter engagement with the inwardly facing recess walls (38), which in turn drives the leg portions (60) of the U-shaped portion (52) outwardly to secure the articles (22, 94) together.

FIELD OF THE INVENTION 
This invention relates to a device for securing electrical articles 
together and more particularly to securing an electrical connector to a 
circuit board. 
BACKGROUND OF THE INVENTION 
U.S. Pat. No. 4,907,987 discloses a connector with a barbed board lock 
including a metal member having barbs supported by spring elements that 
bite into interior wall surfaces of circuit board holes to lock a 
connector thereto. The patent teaches a variety of constructions for 
locking a connector and a circuit board together. 
U.S. Patent application Ser. No. 07/621,407 teaches an improved board 
locking device wherein a planar stamped metal member includes spring beams 
projecting in opposite directions from a center horizontal projection. The 
horizontal projection engages horizontal surfaces within the components 
that are to be secured together. One the spring beams is secured within a 
cavity within a first component and the other spring beam is secured 
within a cavity of a second component to latch to two components together 
in a fixed manner. Each of the spring members have a plurality of 
outwardly extending barbs that engage the interior wall surfaces of the 
respective cavities within the components. The securing or holding power 
of these devices is primarily dependent upon the spring rate of the 
material from which the device is made as well as the shape of the spring 
members. 
In designing board locks or other retention devices, it is desirable to 
minimize the amount of insertion force required to secure to two 
components together and at the same time maximize the retention force 
holding the components together. It is further desirable that a retention 
device be self seating that is requiring no tools to operate the device. 
SUMMARY OF THE INVENTION 
Accordingly the present invention is directed to a connector and holding 
device that alleviates problems and disadvantages associated with prior 
art. The invention is directed to a first electrical article to be mounted 
to a second article. The first electrical article includes a dielectric 
housing having at least one recess for receiving a device that extends 
into the housing from a mounting face thereof and a holding device 
disposed within that recess. The holding device includes a U-shaped 
leading end having a pair of leg portions that are joined by a bight 
portion and define a fastening section adapted to be received within an 
aperture of the second electrical article. The leg portions extend to 
second sections at free ends thereof and define a housing retaining 
section adapted to be received in the housing recess. The housing recess 
includes a central wall portion extending from an inner end of the recess 
to an outer wall proximate the mounting face and divides the recess into 
leg receiving portions, each configured to receive a portion of the 
holding device. 
The holding device is substantially planar has opposed major surface with 
the leg portions having opposed inner and outer edges. The inner edges of 
the leg portions define a gap therebetween. The U-shaped leading portion 
and adjacent first leg portions define spring means and further include 
interference projections extending outwardly from the outer edges of 
engaging wall surfaces within the aperture of the second electrical 
article. The second leg sections have first and second housing engaging 
barbs along the outer edges, the first barbs being proximate the leading 
ends of the second sections and adapted to engage walls within the recess 
proximate the inner end thereof when the holding device is inserted into 
the recess. The second barbs are positioned proximate the mounting face 
and the inner edges of the legs are adjacent the outwardly facing surfaces 
of the central wall inwardly of the leading engagement sites. 
Upon mounting the first article or the connector to a second article by 
inserting the U-shaped leading end of the holding device into the aperture 
of the second article, compressive engagement of the interference 
projections with the aperture wall surfaces causes the first leg sections 
adjacent the leading end to be moved inwardly toward each other. 
Concomitantly therewith, the second leg sections are pivoted about the 
leading engagement sites on the center wall of the recess within the leg 
receiving portions until the first barbs are moved into tighter engagement 
with the corresponding recess walls. This causes an increase in the 
retention forces and in turn drives the interference projections of the 
U-shaped portion more tightly against the aperture wall surfaces such that 
the first electrical article is held securely to the second electrical 
article. In the preferred embodiment , the first electrical article is a 
connector and the second electrical article is a circuit board. 
An object of the present invention is to provide a connector and holding 
device that has sufficient retention force to hold the connector onto the 
board particularly during soldering. 
It is also an object of the invention to provide a holding device that 
secures the device within the housing of the first article as well as 
secures the device to the second article. 
It is an additional object of the invention to provide an improved 
retention or holding device for an electrical article that is actuated 
without the need for separate tooling. 
It is a further object to provide a holding device or boardlock that acts 
mechanically to hold a connector to a circuit board, thereby reducing 
stress on any solder joints during mating and unmating of the connectors, 
particularly when the connector has surface mounted terminals. 
An embodiment of the present invention will now be described by way of 
example with reference to the accompanying drawings.

DETAILED DESCRIPTION OF THE INVENTION 
Referring now to FIGS. 1, 2 and 6, an assembly 20 includes a first 
electrical article or connector 22 mounted to a second electrical article 
or circuit board 94 and held thereon through the engagement of a holding 
device 50 fitted into a recess 32 of the connector housing 24 and through 
hole 96 of circuit board 94. For purposes of illustration, the invention 
is shown to secure a card edge connector 22 of the type adapted to receive 
a daughter card (not shown) and to interconnect pads thereof to terminals 
46 shown in phantom of FIG. 6 which in turn are electrically connected to 
circuit pads 98 as best seen in FIG. 1. It is to be understood that the 
connector and circuit board are representative of the various articles 
with which the holding device of the invention may be used. The invention 
includes the positioning, aligning and holding the components together. 
Connector 22 includes a housing 24 having a mating face 26, an opposed 
mounting face 28 and a plurality of terminal receiving passageways 30 
extending therebetween with a plurality of terminal members 46 disposed 
within respective ones of passageways 30. The mounting face 28 of housing 
24 further includes standoffs 29 for cleaning under connector 22 after a 
soldering operation. Terminal members 46 are shown as surface mount 
terminals having first contact sections 47 for engaging circuits on a 
daughter card and second contact portions 49 for surface engagement with 
traces 98 of the upper surface of board 94. 
Connector housing 24, as best seen in FIG. 2, includes a recess 32 
extending into the housing 24 from a mounting face 28 thereof. Recess 32 
is defined between an outer end 36 proximate the mating face 28, opposed 
inwardly facing surfaces 38 having an inner end 40. Recess 32 further 
includes a central wall portion 42 extending from the inner end 40 to 
outer wall end 36 proximate the mounting face and dividing the recess 32 
into leg receiving portions 34, each configured to receive cooperating 
sections of the mounting device 50 as more fully explained below. Central 
wall 42 includes outwardly facing surface portions 43 extending from the 
inner recess end 40 to leading engagement sites 44 and relief recesses 45 
forwardly thereof. The leg receiving portions 34 have wall surfaces 
defined by central wall 44 and inwardly facing recess walls 38. 
Referring now to FIGS. 2, 3 and 4, holding device 50 includes a U-shaped 
leading end 52 having a pair of leg portions 54 extending upwardly 
therefrom. Leg portions 54 include first sections 60 which are joined by a 
bight portion 62 and define a spring means or fastening section 64, which 
is adapted to be received in aperture 96 of a second electrical article of 
circuit board 94, as shown in FIG. 7. The leg portions 54 extend to 
elongate second sections 70 at free end 71 thereof, defining a housing 
retaining section 73 adapted to be received into the housing recess 32. 
For ease in manufacturing and handling the device 50, the second leg 
portions 70 that are inserted into recess 32 are substantially wider than 
the first leg portions 60, as can best be seen in FIGS. 2 and 3. The 
transition between the first and second leg occurs proximate the mounting 
face 28 of the housing. A downward extending tab portion 76 and inwardly 
directed arcuate surface 78 are provided at the lower end of the second 
leg section to provide strain relief at the transition zone. In addition, 
the leading end of tab 76 provides a surface suitable to be used as a push 
surface by tooling used to set the holding device 50 into housing 24. As 
best seen in FIG. 3, the forming of the terminal with a radius of 
curvature occurs at 82 just immediately below the transition between the 
two-leg portion. This curve can also be seen from the side in FIG. 4. 
Device 50 is substantially planar and has opposed major surfaces 56 with 
the leg portions 54 thereof having opposed inner and outer edges 58,59, 
the inner edges 58 defining a gap 80 therebetween, extending upwardly from 
the U-shaped leading end 52. The first leg sections 60 further have 
interference projections 66,68 extending outwardly along the outer edges 
59 thereof. Projections 66,68 are adapted to engage wall surfaces 97 
within circuit board aperture 96 upon mounting the connector 22 to the 
circuit board 94, as seen in FIGS. 7, and 9. The interference projections 
66,68 extend outwardly to define a dimension that is greater than the 
selected diameter of the aperture 96 in the second article or circuit 
board 94. As also seen in FIGS. 2 and 3, the second leg sections 70 have 
first and second housing engaging barbs 72,74 spaced along the outer edge 
59 thereof with the first barbs 72 being proximate the leading ends 71 
thereof and the second barbs 74 being positioned proximate the connector 
mounting face 28. First barbs 72 are adapted to engage inwardly facing 
walls of recess 32 proximate the inner ends 40 thereof as best seen in 
FIGS. 6 and 8. Upon inserting the holding device 50 into cavity 32 such 
that the second leg sections 70 are received in the corresponding leg 
receiving recess 32 portions 34, the respective barbs 72,74 engage the 
inwardly facing recess walls 38, as best seen in FIGS. 6, 8 and shown in 
phantom in FIG. 10. The inner edges 58 of second leg sections 70 are 
adjacent the outwardly facing surface portions 43 of central wall 42 
inwardly of the leading engagement sites 44. Insertion of device 50 is 
facilitated by the use of a tool pushed against the flat leading end of 
tab 76. The housing barbs, 72,74 engage recess walls 38 to secure device 
50 in housing 24 and hold the device 50 therein until the connector or 
other article is to be joined to the board or other article. 
Upon mounting the connector 22 to the circuit board 94 by inserting the 
U-shaped leading end 52 of the holding device 50 into board aperture 96, 
the interference projections 66,68 are placed in compressive engagement 
with the aperture sidewall 97 causing the first leg sections 60 of the 
U-shaped leading end 52 to be moved inwardly toward each other at a given 
spring rate, as best seen in FIGS. 7, 9 and 10. Concomitantly therewith, 
the second leg sections 70 are pivoted outwardly about the leading 
engagement sites 44 within the respective leg receiving portions 34 until 
the first barbs 72 are moved into tighter engagement with the inwardly 
facing recess walls 38 and the upper portions 70 have rotated sufficiently 
to obtain a double support from the housing resulting from forces 
generated from the interaction between inner leg surface 58 and wall 
engagement site 44 and the interaction between first barbs 72 and recess 
walls 38. Once double support has been achieved, the retention forces will 
increase as the connector is moved further toward the board and the 
resultant force will hold the connector securely to the board during 
subsequent manufacturing and in particular during soldering. The increased 
retention force in turn drives the interference projections 66,68 more 
tightly against the aperture wall surface 97 such that the first 
electrical article 22 is held securely to the second electrical article 
94, as shown in FIGS. 7, 9 and 10. The relative movement of the holding 
device 50 within the recess 32 and aperture 96 can best be seen by 
referring to FIG. 10 which shows the position of holding device 50 in the 
unmounted connector in phantom and the position of the holding device 50 
in the mounted connector by the solid lines. 
Connector housing 24 may be molded from a number of suitable dielectric 
materials, as known in the art. The retaining device 50 is preferably 
stamped from flat stock, such as copper alloys, phosphor bronze, steels or 
the like. Device 50 may be soldered in place or may be used solely as a 
mechanical holding device. If the device is to be soldered, typically the 
metal will plated to enhance solder wetting. The thickness and width, 
particularly in the spring means or lower fastening section 64, is 
adjusted to get a desired retention force between the connector and the 
board. The size of device 50 will also depend on the size of the 
connector, the number of devices 50 being used, the properties of the 
material selected and the amount of retention force exerted by each of the 
devices. The electrical conductivity of the selected material is not 
important consideration, since device 50 is not being used as an 
electrical terminal. In the preferred embodiment, the board retention 
section 60 is slightly formed by twisting at 82 as best seen in FIG. 3 in 
a surface of revolution of slight curvature about an axis co-parallel with 
the leg portions. This curvature is best seen in FIG. 5, which shows a 
cross-section of device 50 with the barbs 66 in engagement with the walls 
97 of aperture 96. 
The present invention provides an improved retention or holding device for 
an electrical article that is actuated without the need for separate 
tooling. The holding device furthermore acts mechanically to hold a 
connector to a circuit board, thereby reducing stress on any solder joints 
during mating and unmating of the connectors, particularly when the 
connector includes surface mounted terminals. The double support of the 
housing walls in cooperation with the second spring leg portions 70 
assures retention of the holding device in the housing 24 as well as 
provides an increase in force to retain the connector and holding device 
to the circuit boards. The board retention means obviates the need for 
under board tooling and will accommodate a wide range of tolerances in 
both the thickness of the circuit boards and the board lock receiving 
apertures as well as different thicknesses of the circuit boards. 
As can be appreciated, more than one holding device 50 may be used in a 
given connector depending on the length thereof. An appropriately 
configured recess may be provided in selected inner as well as outer 
housing walls, or may be within outwardly extending flanges. Since the 
device is inserted into the recess from the mounting face of the connector 
and is activated by the process of mounting the connector to a board or 
other article, access to the recess from the mating face is not necessary. 
Use of the holding device of the invention, therefore, does not conflict 
with the configuration of the mating face of the connector. 
It is thought that the board retention device and connector assembly of the 
present invention and many of its attendant advantages will be understood 
from the foregoing description. Changes may be made in the form, 
construction and arrangement of parts thereof without departing from the 
spirit and scope of the invention or sacrificing all of its material 
advantages.