1. Field of the Invention
[0001] This invention relates to electrical connectors and more particularly to an electrical
connector for connection to an edge of a single-sided printed circuit board.
2. Description of the Prior Art
[0002] There are a wide variety of electrical connector assemblies which are adapted to
be mated to an edge of a printed circuit board. Many of these edge connectors include
a mating slot which receives a tongue portion projecting from an edge of a printed
circuit board. Many such connectors also include fastening means, such as screws or
bolts, for mounting the connector housing to the printed circuit board.
[0003] In most such electrical edge connectors which have elongated slots for receiving
an edge portion or end of a board, a plurality of terminals are mounted in the housing
along the slot, and spring contact portions of the terminals are biased against contact
pads on either one or both sides of the printed circuit board. These types of connectors
generally suffer from the disadvantage of connector tilting which may cause interruption
of the electrical pathway or bending of the contacts. To overcome this problem, many
connectors rigidly clamp the board within the connector slot against movement perpendicular
to the plane of the board. Such clamping often includes the use of screws traversing
holes found in the printed circuit board. Such through-hole clamping means is not
suitable for certain manufacturing and assembly processes, such as oven/IR reflow
soldering.
[0004] Rigidly clamping the connector to the printed circuit board causes a myriad of other
problems. Such problems include the spring contact portions of the terminals losing
their resiliency and, accordingly, the effective biased engagement with the pads on
the printed circuit board. Additionally, problems arise from stress cracks produced
in the areas surrounding the fastening means which lock the connector to the board.
Such stress cracks may create open circuits if the crack traverses a printed circuit.
[0005] United Kingdom patent application number 9103039.5 (GB-A-2 242 579) discloses an
electrical connector with an insulative housing having at least one row of terminal
pins secured in and extending outwardly from one side of the housing. The connector
further comprises spaced latch members at the ends of the housing which extend in
the same direction as the terminal pins and have protuberances at their outer ends.
When a flat insulated board is fully inserted into the connector, the protuberances
fit into openings in the board.
[0006] To avoid the problems associated with edge connectors, conventional header designs
are typically surface mount connectors or right-angle connectors. Surface mount connectors
usually use "hooks" to secure the connector to the printed circuit board. This design
suffers greatly from connector tilling problems, similar to the previously described
edge connectors, as well as problems associated with solder lead coplanarity control.
These problems lead to connector manufacturing difficulties and poor solder joint
formation during automated soldering processes to couple the solder leads to the solder
pads of the printed circuit board.
[0007] Right-angle connectors also suffer the disadvantage of tilting as well as kinking
of the solder leads which are used to assist in holding the connector upright. To
avoid tilting and kinking problems, these connectors generally utilise screws and
mating through holes on the printed circuit board to rigidly couple the connector
to the board. Thus, right-angle connectors suffer from the disadvantages set forth
above regarding stress cracks as well as manufacturing and assembling difficulties
discussed above.
[0008] The present invention overcomes the problems set forth above to provide a superior
design substitute for surface mount and right-angle printed circuit board connectors.
SUMMARY OF THE INVENTION
[0009] It is an object of the present invention to provide an improved single-sided, straddle
mount connector for mounting to a printed circuit board.
[0010] It is a further object of the present invention to provide a single-sided, straddle
mount printed circuit board edge connector having improved positive grip on the printed
circuit board.
[0011] It is yet another object of the present invention to provide a single-sided, straddle
mount printed circuit board edge connector having improved Z-height control without
sacrificing connector rigidity.
[0012] It is still a further object of the present invention to provide a single-sided,
straddle mount printed circuit board edge connector having improved solder joint formation
by positively pre-loading the leads onto the printed circuit board to ensure good
mating contact.
[0013] It is yet another object of the present invention to provide a single-sided, straddle
mount printed circuit board edge connector adapted to accommodate and correct warpage
of thin printed circuit boards which often occurs during the soldering process.
[0014] It is still a further object of the present invention to provide a single-sided,
straddle mount printed circuit board edge connector having a plurality of gripper
or arm assemblies on the connector which provide an effective means for correcting
printed circuit board warpage.
[0015] It is still a further object of the present invention to provide a single-sided,
straddle mount printed circuit board edge connector having positive grip gripper arm
assemblies on the connector which eliminate tilting of the connector with respect
to the printed circuit board.
[0016] It is yet another object of the present invention to provide a single-sided, straddle
mounted printed circuit board edge connector having improved coplanarity control of
solder leads, leading to simpler and easier manufacturing processes due to increased
tolerances.
[0017] It is still another object of the present invention to provide a plastic, single-sided,
straddle mount printed circuit board edge connector which provides enhanced plastic
rigidity using I-beam and C-channel designs for the gripper arm assemblies.
[0018] It is yet a further object of the present invention to provide a plastic, single-sided,
straddle mount printed circuit board edge connector which improves plastic material
flow to thin sections of the connector during injection molding.
[0019] In accordance with the present invention there is provided a connector for mounting
to the edge of a printed circuit board having solder pads on one side thereof, said
connector comprising: an elongate insulative housing having a top wall, an opposed
bottom wall and spaced apart end walls; a plurality of electrical contacts supported
by said housing along the length thereof in at least one row, said contacts having
resilient solder tails extending from said housing for resilient electrical engagement
with said solder pads on said one side of said printed circuit board; a pair of gripper
arms formed with said housing and extending from said housing adjacent each end of
said row of said contacts in facing opposition to said solder tails, said gripper
arms forming with said resilient contact solder tails a board receiving space for
resilient accommodation of said board therebetween; and an intermediate protrusion
formed with and extending from said housing at a location intermediate said pair of
gripper arms in facing opposition to said resilient solder tails, wherein said intermediate
protrusion is for supporting only a second side of said printed circuit board, said
intermediate protrusion and said resilient solder tails further defining said board
receiving space.
[0020] In a specific embodiment, the walls of the housing form a header assembly and each
of the electrical contacts are positioned within at least one opening which extends
through the rear wall of the housing. The electrical contact includes a contact pin
portion which is positioned within the header assembly and the solder tails extend
from the rear wall of the housing in a direction opposite from the header assembly.
The gripper arms are spaced along the insulative housing and extend perpendicular
from the rear wall of the header portion of the connector in the direction of the
solder tails. Each of the gripper arm assemblies includes an upper and lower gripper
arm defining therebetween the board receiving space. The gripper arm assemblies provide
positive mechanical locking of the printed circuit board to the connector so that
the solder lead is in mating electrical connection with the solder pad of the printed
circuit board upon insertion therein.
[0021] The gripper arm assemblies may be in the form of simply providing an upper and lower
gripping arm or, in the alternative, may be configured as either an I-beam or C-channel
shaped. In the gripper arm assembly configured in the shape of an I-beam, the assembly
includes upper and lower gripper arms and a vertical extending member disposed between
and coupled to the upper and lower gripping arms to form substantially an I-shaped
cross-section. In order for the printed circuit board to be inserted into the I-beam
shaped gripper arm assembly, the printed circuit board includes a slot therein for
mating engagement with the vertical extending member of the I-beam.
[0022] The gripper arm assembly configured in the shape of a C-channel includes a vertically
extending member coupling an outside surface of the upper and lower gripper arms to
form the gripper arm assembly having a C-shaped cross-section. Depending on the location
of the C-channel shaped gripper arm assembly along the edge of the printed circuit
board, the printed circuit board may include a slot therein for mating engagement
with the vertical extending member of the C-channel.
[0023] The connector is preferably integrally molded to include the header and gripper arm
assemblies as a unitary body. The contacts may be press fit into openings in the rear
wall of the header assembly to form the connector in accordance with the present invention.
The gripper arm assemblies of the present invention provide superior mechanical connection
to the printed circuit board and avoids connector tilting problems without the use
of any fastening means such as through holes and screws. The connector of the present
invention also provides an easily manufacturable structure which can be simply assembled
onto an edge of a single-sided printed circuit board.
[0024] A preferred form of the single-sided, straddle mount printed circuit board connector,
as well as other embodiments, objects, features and advantages of this invention will
be apparent from the following detailed description of illustrative embodiments thereof,
which is to be read in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025]
Figure 1 is a top perspective view of the single-sided, straddle mount connector coupled
to an edge of a printed circuit board;
Figure 2 is an enlarged detail of the connector and printed circuit board shown in
Figure 1;
Figure 3 is a rear elevational view of the connector header assembly;
Figure 4 is a top plan view of the connector
Figure 5 is a cross-sectional view of a connector illustrating the connector insertion
direction onto an edge of a printed circuit board;
Figure 6A is a front elevational view of the connector illustrating the printed circuit
board seating plane and the coplanarity tolerance of the connector solder leads;
Figure 6B is an enlarged perspective detail of the connector solder tail in mating
electrical connection with a solder pad of a printed circuit board;
Figure 7 is a front elevational view of the connector and printed circuit board warp
correction provided by the connector gripper arm assemblies;
Figure 8 is an end view of the connector and gripper arm assembly with a printed circuit
coupled thereto;
Figure 9 is a perspective view of a connector gripper arm assembly configured in the
shape of an I-beam and a mating portion of a printed circuit board;
Figure 10 is a vertical cross-sectional view of the gripper arm assembly configured
in the shape of an I-beam illustrated in Figure 9;
Figure 11 is a horizontal cross-sectional view of the gripper arm assembly configured
in the shape of an I-beam and a mating portion of the printed circuit board illustrated
in Figure 9;
Figure 12 is a vertical cross-sectional view of a connector gripper arm assembly configured
in the shape of a C-channel.
Figure 13 is a perspective view of a simplified auto-insertion machine for coupling
the connector on an edge of a single-sided printed circuit board.
Figure 14 is a partial front perspective showing of the embodiment of the connector
assembly of the present invention.
Figure 15 is a back elevational view of the connector shown in Figure 14.
Figure 16 is a bottom perspective view of the connector of Figure 14 supporting a
printed circuit board.
Figure 17 is a bottom perspective showing of the connector of Figure 14.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0026] Figure 1 is a top perspective view of a single-sided, straddle mount connector 10
coupled to an edge of printed circuit board 20. The connector 10 includes a plurality
of contacts or solder leads 12 which are in electrically mating connection with solder
pads 14 located on a top surface of the printed circuit board 20. Also shown in Figure
1 are a plurality of connector gripper arm assemblies 16 which provide a positive
locking means for coupling the connector 10 to the edge of the printed circuit board.
[0027] The connector 10 is single-sided since the solder leads 12 are provided on only one
side of the printed circuit board. Many prior art devices included solder pads on
two opposing surfaces of the printed circuit board and a connector having top and
bottom contacts for electrically contacting each solder pad. These types of double-sided
printed circuit boards have many disadvantages, including manufacturing difficulties,
such as those associated with double reflow and double-sided solder pasting. Since
the present invention only requires a single side of the printed circuit board to
include solder pads, manufacturing speed is increased and the above-mentioned difficulties
are avoided. A printed circuit may be produced and easily pasted to a top surface
of a substrate to form a printed circuit board.
[0028] Figure 2 is an enlarged detail of Figure 1. As clearly illustrated in Figure 2, the
connector contacts or solder leads 12 are spring-retention type contacts which are
frictionally electrically connected to the solder pads 14 of the printed circuit board
20 upon insertion of the circuit board into the receiving space formed by gripper
arm assemblies of the connector. The solder leads 12 are shaped to be biased against
an inserted circuit board so that a solder tail 18 of the solder lead are electrically
coupled with a solder pad of the circuit board. The solder leads 12 include at least
one bend along its extent and the solder tail 18 is curled upward for receiving an
edge of a printed circuit board 20 without scraping the circuit board surface.
[0029] Figures 3 and 4 illustrate one embodiment of the header assembly of the single-sided
straddle mount connector. More specifically, Figure 3 is a rear elevational view of
the connector illustrating the arrangement of male connection power pins 22 and signal
pins 24. The connector housing 26 comprises an electrically insulative material, such
as glass filled PPS or PPA. The connector includes a plurality of male power pins
22 for connection with a mating female power plug. Furthermore, the connector may
include any number of signal pins 24, depending upon the application. Figure 4 is
a top plan view of the connector housing illustrating the gripper arm assemblies and
spring retention contacts 28 coupled to the power pins and the contacts 12 coupled
to the signal pins of the connector. In this particular illustrated embodiment, the
connector includes three gripper arm assemblies, one gripper arm assembly at each
end of the connector 16a, 16c and a third gripper arm assembly 16b located near a
central portion of the connector. The connector housing also includes an indicator
30 which may be molded into the housing, for indication the position of the first
signal pin positioned within the connector.
[0030] Figure 5 is a cross-sectional view of the connector 10 prior to connection with an
edge of a printed circuit board 32. In practice, the connector will be moved along
a plane in the direction of an edge of printed circuit board for mating mechanical
and electrical connection therewith. The connector is manufactured to accommodate
any specified printed circuit board thickness, e.g. 1.45 mm. Accordingly, the printed
circuit board is frictionally fitted between an upper 34 and lower 36 gripper arm
to positively mechanically hold the connector to an edge of the printed circuit board.
The lower gripper arm 36 extends a sufficient length perpendicular to an edge of the
printed circuit board to effectively support the connector on the edge thereof. For
example, the lower gripper arm assembly is preferably at least 4mm long extending
from a rear wall 38 of the connector. The gripper arm assemblies may be any convenient
width, and are typically 2 to 5mm in width. By supporting the connector along its
length with a plurality of gripper arm assemblies, connector tilting problems are
avoided.
[0031] This arrangement of a plurality of gripper arm assemblies to positively lock the
connector to the printed circuit board has numerous advantages of prior designs. For
example, the novel arrangement of gripper arm assemblies eliminates the serious problem
of connector tilt with respect to the printed circuit board. Additionally, the contacts
or solder leads of the connector may be designed with positive pre-load interference
to improve electrical contact with the printed circuit board solder pads without danger
of tilting the connector. Furthermore, the arrangement of gripper arm assemblies serve
as an effective means for correcting printed circuit board warpage, which feature
will be discussed in greater detail later.
[0032] Figure 6A illustrates the positively pre-loaded solder leads. More specifically,
the solder leads 12 have solder tails 18 with a rounded contact surface which is set
below a printed circuit board seating plane 40 defined by a gripper arm assembly receiving
space 42. The receiving space 13 defined by an upper surface 44 of a lower gripper
arm and a lower surface 46 of an upper gripper arm. (Figure 5). Accordingly, the solder
leads 12 are positively pre-loaded onto the printed circuit board solder pads to provide
good electrical contact therewith. Additionally, as illustrated in Figure 6A, control
of coplanarity of the solder tails may be relaxed without sacrificing the ability
to make good electrical contact with the printed circuit board. As shown in Figure
6A, a printed circuit board seating plane is illustrated by dashed line 40. The contact
tails will provide good electrical contact with the printed circuit board as long
as the contact tails, in their relaxed position, are oriented below the seating plane
of the printed circuit board. However, in the event that the solder tails 18 are formed
above the printed circuit board seating plane, that is, there is an absence of preloading
of the solder leads 12 onto the printed circuit board solder pads, good solder joints
may still be attainable as long as the solder tails 18 do not lift off the printed
circuit board seating plane by a distance more than the solder pad thickness (Figure
6B). Typically, solder pads have a thickness of 0. 15mm as illustrated by arrows A-A
in Figure 6B. Accordingly, if the solder tail is formed above the printed circuit
board seating plane by a distance less than the solder pad thickness, (shown by arrows
B-B in Figure 6B) good solder joints may be formed. The tolerance of coplanarity is
indicated by the seating plane 40 and a lower limit illustrated by dashed line 42.
Thus, connector manufacturing methods and processes become simplified in view of the
increased tolerance permitted with respect to contact tail coplanarity. Also illustrated
in Figure 6A are the connector openings 43 through which the male contact pins and
solder leads are mounted to the connector.
[0033] Figure 7 is a front elevational view of a single-sided, straddle mount connector
of the present invention illustrated with a warped printed circuit board 44. Commonly,
printed circuit boards tend to warp due to shrinkage or other post-manufacturing conditions.
Due to this warping, it becomes very difficult, if not impossible, to use any form
of edge connector and still obtain good electrical connection along the entire length
of the connector. The present embodiment which includes a plurality of gripper arm
assemblies can effectively correct printed circuit board warpage and ensure good electrical
contact. As shown in Figure 7, the single-sided, straddle mount connector includes
three gripper arm assemblies 16a, 16b, 16c, illustrated in an I-beam configuration
to be discussed in greater detail later, which upon connection to an edge of a warped
printed circuit board 44, will tend to straighten and positively grip the printed
circuit board. Warpage becomes a significant problem with thin printed circuit boards
and, this problem can be rectified by the arrangement of gripper arm assemblies on
a single-sided connector of the present invention. Once the warped circuit board is
in place in the connector, the circuit board warp is corrected to provide a substantially
planar connection surface 46.
[0034] Figure 8 is an end view of the single-sided, straddle mount connector illustrating
a gripper arm assembly having a single-sided, paste on printed circuit board seated
within the gripper arm assembly receiving space. The gripper arm assembly includes
a lower arm 36, having an upper surface which determines the Z-height (center line
offset) of the printed circuit board. Specifically, depending upon the positioning
and/or thickness of the lower gripper arm 36, the Z-height of the printed circuit
board is determined. The particular configuration of the upper gripper arm 34 and
lower gripper arm 36 provides superior Z-height control.
[0035] The connector housing 26 is preferably an integrally molded unit having the connector
header 27 (Figures 3 and 4) and gripper arm assemblies 16a, 16b, 16c integrally formed.
The connector header includes top and bottom walls, opposed side walls and rear wall
38. The connector contacts, comprising a male connector pin at one end and a solder
lead at an opposite end, may include rectangular transition section 49 (Figure 6),
which may be press fit into contact receiving spaces 43 molded into the housing. The
contacts include a single-sided solder lead on the printed circuit board receiving
side and male connector pins for coupling to mating female connectors within the header
assembly of the connector. The gripper arm assemblies 16a, 16b, 16c include a receiving
space 42 between the upper 34 and lower 36 gripper arms, the receiving space 42 being
specifically dimensioned to receive a printed circuit board having a specified thickness.
[0036] In the embodiment shown in Figure 8, the lower gripper arm 36 is substantially rectangular
in shape and having a rectangular cross-section. The upper gripper arm 38 is also
substantially rectangular in shape, but being tapered away from the header 27 towards
the printed circuit board receiving space opening and having a substantially rectangular
cross-section throughout its length.
[0037] The lower gripper arm 36 may include on a top surface thereof at least one projection
or crush rib 48 extending upward from the top surface thereof to engage the lower
surface of the printed circuit board. The at least one projection or crush rib 48
aids in providing a positive mechanical lock of the connector onto the edge of the
printed circuit board. In one embodiment, a single crush rib may be centrally located
on an upper surface of the lower gripper arm. Alternatively, as shown in Figures 7
and 9-11, a pair of crush ribs 48 may be provided on opposite sides of the lower gripper
arm for deflection upon engagement with the lower surface of a printed circuit board.
[0038] Once good mechanical and electrical connections are formed by the gripper arm assemblies,
the solder tails may be fused to the solder pads of the printed circuit board. Such
fusing may be accomplished by oven/IR reflow soldering thus providing a fast, reliable
electrical connection therebetween.
[0039] Figures 9- 11 illustrate alternative embodiments of forming the gripper arm assemblies.
More specifically, Figure 9 illustrates a gripper arm assembly 16 and connector housing
header wherein the gripper arm assembly has an I-beam construction. More specifically,
the gripper arm assembly 16 includes a lower gripper arm 36 and an upper gripper arm
34 defining a printed circuit board receiving space 42 therebetween and a strengthening
rib 50 assembly centrally located in the circuit board receiving space. The strengthening
rib 50 is integrally formed into the lower surface of the upper gripper arm and the
upper surface of the lower gripper arm. The I-beam construction provides enhanced
strength to the gripper arm assembly.
[0040] The I-beam construction allows the thin plastic sections of the gripper arm assemblies
to withstand heavier loads without risk of fracture. Since the I-beam construction
provides enhanced strength to the gripper arm assembly, a wider range of Z-heights
are available since the lower gripper arm may be made thinner without sacrificing
connector load capabilities. However, when utilizing the I-beam construction, it will
be necessary to provide a slot 52 in the printed circuit board for accommodating the
strengthening rib of the gripper arm assembly as shown in Figure 9. The slot 52 in
the printed circuit board and I-beam construction of the gripper arm assembly act
as a printed circuit board-to-connector alignment means. Accordingly, the printed
circuit board solder pads will be closely aligned with the solder leads of the connector
to ensure good electrical connection to all solder pads on the printed circuit.
[0041] Yet another advantage of the I-beam construction is improved manufacturability of
the connector. More specifically, the connector is preferably injection molded plastic
in an integrally formed device. However, problems may arise in the injection molding
process due to poor plastic flow to thin sections of the connector, e.g. the gripper
arm assemblies. The I-beam construction provides improved plastic flow to the thin
sections of the gripper arm assemblies to enhance the overall plastic injection molding
process.
[0042] Also shown in Figure 9 are the crush ribs 48 which are provided on the upper surface
of the lower gripper arm 36. The crush ribs 48 are substantially triangular-shaped
projections having a peak which extends above the upper surface of the lower gripper
arm on opposing side edges thereof. As previously discussed, the crush ribs 48 are
adapted to slightly deflect to ensure a positive mechanical lock of the connector
to the edge of the printed circuit board. The crush ribs 48 are clearly illustrated
in Figures 10 and 11 which are partial cross-sectional views of the connector and
gripper arm assemblies shown in Figure 9.
[0043] Figure 10 is a partial vertical cross-sectional view of the connector housing and
gripper arm assembly formed in accordance with the I-beam construction described above.
Also illustrated in Figure 10 are the openings 43 molded into the housing which are
adapted to receive the connector contacts. As previously noted, the connector contacts
may be press-fit into the housing openings 43 so that a male connection pin end is
available for connection within the header portion of the connector and the solder
leads 12 extend in an opposite direction for frictionally engaging solder pads on
a top surface of a printed circuit board.
[0044] Figure 11 is a partial horizontal cross-sectional view of the connector housing 27,
strengthening rib 50 and lower gripper arm 36. The strengthening rib 50 is integrally
molded to the connector housing and lower gripper arm. The strengthening rib 50 is
dimensioned to fit within the slot 52 formed in the printed circuit board for alignment
of the connector with the printed circuit board.
[0045] Figure 12 illustrates a further alternative embodiment in perspective view for the
gripper arm assembly. Figure 12 illustrates a partial vertical cross-section of a
C-channel gripper arm assembly design in which a receiving space is defined between
an upper 34 and lower arm 36 portion and a rear portion 54 connecting the upper and
lower gripper arm portions. Once again, the C-channel design affords the strength
advantages in the thin plastic sections of the gripper arm assembly. The C-channel
design also allows for broader design options with respect to Z-height of the connector.
[0046] It should be understood by those skilled in the art that the different gripper arm
assembly designs may be used in any combination in the connector design. For example,
the connector may include C-channel design gripper arm assemblies on the end portions
of the connector and at least one I-beam gripper arm assembly along the length of
the connector. Alternatively, the connector may include all I-beam design gripper
arm assemblies or standard gripper arm assemblies (Figure 5) which include only an
upper and lower gripper arm extending from the connector housing.
[0047] Figure 13 illustrates a simplified auto-insertion machine for coupling the single-sided,
straddle mount connector to an edge of a printed circuit board. The auto-insertion
machine includes a magazine holder for stacking a plurality of connectors 10 and an
insertion device 62 for pushing the connector 10 onto the edge of the circuit board
20. The insertion device includes a pneumatic cylinder 64 having an insertion block
66 coupled to the reciprocating rod 68 of the cylinder. Upon activation of the cylinder,
the insertion block 68 contacts the header portion of the connector which is pushed
in the direction of arrow A to contact an edge of the circuit board 20. The connector
spring retention solder leads are frictionally, electrically coupled to the solder
pads on the circuit board upon complete insertion of the connector onto the edge of
the circuit board. A soldering process may then permanently fuse the solder leads
to the solder pads. Accordingly, the present invention provides a positive mechanical
lock and reliable electrical connection to a single-sided, printed circuit board utilizing
a simple assembly process. The assembly process does not require any additional connection
devices, such as threaded screws, to ensure good mechanical and electrical contact.
The gripper arm assemblies positively engage the edge of the circuit board to ensure
a good mechanical connection.
[0048] The single-sided, straddle mount printed circuit board connector overcomes the disadvantages
of surface mount and right-angle connectors, including connector tilting and provides
positive mechanical and electrical coupling with the circuit board. Furthermore, the
assembly process of the connector to the edge of the circuit board is simplified.
Manufacturing of the connector is also simplified in view of the higher tolerances
permitted for coplanarity of the contact solder tails without sacrificing good electrical
connection to the solder pads of the printed circuit board. The connector is also
effective in correcting printed circuit board warpage using the gripper arm assemblies
described herein.
[0049] As particularly shown in Figures 4, 6, and 7, the present embodiment provides for
securing printed circuit board 40 to connector 10 in a manner which accommodates variation
in the coplanarity of the solder tails 18 extending from housing 26. The present embodiment
also compensates for a certain degree of printed circuit board warpage, assuring that
such warpage of the printed circuit board is corrected thereby providing good electrical
engagement between the solder tails 18 and the pads on one surface of the printed
board over the entire length of the connector. As described above, this is achieved
by use of gripper arms 16 which extend from housing 26. Particularly with respect
to signal pins 24, both coplanarity of the solder tails 18 and printed board warpage
is accommodated by gripper arm 16c, at one end of housing 26 and third gripper arm
16b located along a central portion of housing 26. While such arrangement and positioning
of the gripper arms is adequate for the intended purposes, it is further contemplated
that additional compensation for printed circuit board warpage and lack of coplanarity
of solder tails may be further addressed by the addition of an intermediate gripper
arm specifically associated with contacts 12 of signal pins 24.
[0050] Referring now to Figures 14-17 corresponding to the present invention, single-sided
straddle mount connector 10 additionally includes an intermediate protrusion 17 which,
as particularly shown in Figures 16 and 17, is supported along a bottom surface 26a
of housing 26 and extends forward of a front edge 26b thereof. Protrusion 17 which
serves as an additional gripper arm is located approximately equidistant between gripper
arm 16c and gripper arm 16b. Between such expanse, connector 26 supports at least
one row of densely arranged signal contacts having solder tails 18 extending therefrom.
While the arrangement of the gripper arm 16a, 16b and 16c described above adequately
provides for a certain degree of non-coplanarity of solder tails 18 and a certain
degree of printed circuit board warpage, the positioning and location of intermediate
protrusion 17 compensates for additional non-coplanarity of the solder tails and a
higher degree of printed circuit board warpage.
[0051] Non-coplanarity of the solder tails as well as printed circuit board warpage, especially
along the solder tails 18 of the signal contacts, can result in incidents of non-soldered
connections between certain of the solder tails 18 and the traces on the printed circuit
board. Such problems are especially encountered when the connector is being implemented
by the end user where variations in the thicknesses of the printed circuit board may
result in a relatively thin board being employed. Such a thin board would enhance
the above noted problems. Also storage of these boards at a user's location may, over
time, result in enhanced warpage problems. Still further during the soldering process,
PC boards have a tendency to be warped or deformed when exposed to high temperatures
necessary for effecting a proper solder. Problems my also be encountered in the connector
itself . In certain instances, warpage or deformation of the plastic connector housing
is possible due to built-in molding stresses which may occur during the formation
of the connector or due to high temperature exposure during the soldering process.
[0052] The addition of intermediate protrusion 17 additionally addresses such problems and
results in more accurate and reliable solder connections between solder pads 18 and
the traces on printed circuit board 20. This is especially significant along the extent
between gripper arm 16b and end gripper arm 16c such extent being unsupported in the
embodiment shown above in Figures 4, 6 and 7.
[0053] As set forth above, protrusion 17 may be integrally formed with connector housing
26. Protrusion 17, along with gripper arms 16b and 16c, forms a board receiving space
with solder tails 18 for receipt of the edge of board 40. The board receiving space
is such that the solder tails are biased against the edge of printed circuit board
40 assuring spring engagement therewith so as to compensate for lack of coplanarity
of the tails along the entire row of contacts. Further, the upper surface 17a of protrusion
17 may include a central crush rib 17b extending therefrom for engagement with board
40 to help maintain the board 40 in place. The crush rib 17b may also be used to locate
and align the board in the board receiving space.