[0001] The subject invention relates to an electrical connector for interconnecting circuitry
on a flat flexible cable to further circuitry on a printed circuit board.
[0002] A need exists within the electronics industry for low height electrical connectors
which can terminate flexible cable to printed circuit boards. This connector should
also provide for easy insertion and withdrawal of the flexible circuitry and be prestressed
to allow for adequate contact force against the circuitry of the flexible cable.
[0003] One connector is shown in EP Publication 0 263 296 where the flexible circuit can
be placed in the front face of the connector, and interconnected to a printed circuit
board. In this connector, an upper cover is rotatable about the housing and a front
nose of the cover lifts the contacts out of contact. While this disclosure indicates
that the terminals are prestressed, no easy components are included on the terminal
design for facilitating the preload.
[0004] It is an object of the invention to provide an easy and efficient method of providing
a prestressed electrical terminal.
[0005] It is an object of the invention to design an electrical connector for an electrical
connection between a substrate having printed circuits thereon, and to further conductive
elements, where the connector includes an insulating housing comprising a plurality
of terminal passageways for receiving a plurality of edge stamped electrical terminals,
and where the electrical terminals have opposed contact members which effect the electrical
connection with the printed circuits
[0006] The inventive method of manufacturing the terminals as described above is then is
characterized by the steps of:
edge stamping the terminals to provide a horizontal base portion with a spring arm
extending from the horizontal base portion and having a first contact member extending
from the spring arm and towards the horizontal base portion, and having an extension
arm extending from the horizontal base portion at an acute angle relative to the horizontal
base portion and in an opposite direction from the spring arm, the extension arm having
a second contact member thereon, which is spaced from the first contact portion; and
subsequently bending the extension arm towards the spring arm to position the first
and second contact portions in an opposed and facing relation.
[0007] Subsequent to the edge stamping, but prior to the bending of the extension arm, the
first and second contact members are plated.
[0008] Preferably, the extension arm is bent into the spring arm in a dimension which preloads
the first and second contact portions against each other.
[0009] Preferably a retention arm extends from the extension arm forward of the second contact
member.
[0010] In the preferred embodiment of the invention, the housing has a plurality of apertures
extending in the housing, where the retention arms may reside. A substrate receiving
surface is integral with the housing and extends above and transverse to the apertures.
The terminal receiving passageways are defined by a floor which extends beyond the
aperture. The lower edge of the horizontal base portion is in abutment with the floor.
[0011] Preferably, the terminals include a weakened section between the horizontal base
portion and the extension arm to facilitate bending.
[0012] Preferably, an edge of the second contact portions are in abutment with an end surface
of the substrate receiving surface, with the upper contact area of the second contact
members extending above the plane defined by the substrate receiving surface.
[0013] The preferred embodiment of the invention will now be described, by way of example,
with reference to the accompanying drawings, in which:-
Figure 1 is an isometric view showing the cam member and the terminals assembled to
the housing;
Figure 2 is an isometric view similar to that of Figure 1 showing the connector prior
to the installation of the terminals and the cam member;
Figure 3 is an isometric view similar to that of Figures 1 and 2 showing a partial
cut away view of the connector when the terminals are in an undeflected condition;
Figure 4 is an isometric view similar to that of Figure 3 showing the cam member in
a fully rotated position with the contacts deflected and poised for receipt of a flat
cable;
Figure 5 is a cross-sectional view through lines 5-5 of Figure 1;
Figure 6 is a cross-sectional view similar to that of Figure 5 absent the electrical
terminal;
Figure 7 is a cross-sectional view through lines 7-7 of Figure 1;
Figure 8 is a cross-sectional view similar to that of Figure 7 absent the hold down
terminal.
Figure 9 is side plan view of the electrical terminal prior to the final formation;
Figure 10 is a side plan view of the electrical connector configured for surface mount
applications;
Figure 11 is an isometric view similar to that of Figure 1 showing an optional shielded
version;
Figure 12 is a cross-sectional view of an alternate embodiment where the connector
is vertically arranged and for through hole printed circuit board mount; and
Figure 13 is a view similar to that of Figure 12 for surface board mounting of printed
circuit boards.
[0014] With reference first to Figure 1, the electrical connector 2 of the subject invention
relates to a connector which can interconnect electrical traces 202 of a flat flexible
cable, such as 200 to a printed circuit board 210. The electrical connector 2 generally
comprises a housing 4 holding a plurality of electrical terminals 150, and further
comprises a cam member 100 which can be rotated in the counter-clockwise direction
(as viewed in Figure 1) to deflect the terminals to a position where the flexible
cable 200 can be inserted without an insertion force. This type of electrical connector
is usually referred to as a zero insertion force or ZIF electrical connector.
[0015] With reference to Figure 2, the housing 4 will be described in greater detail. The
housing 4 is generally comprised of an insulating material such as a glass filled
thermoplastic and generally includes a top wall 6, a recessed surface 8, a rear surface
10, a lower mounting surface 12, side walls 14 and 16 and a front mating face 18.
The housing further comprises a plurality of ribs 24 which extend from a position
proximate the front face 18 to the rear surface 10. The profile of the ribs at the
front edge is defined by slanted edges 26, and by a plurality of side by side semi-circular
edges 28. The housing 4 further comprises a plurality of apertures 50 which are in
side by side alignment with the terminal receiving cavities 54. The cavities 54 are
defined by side surfaces 56 and 58 as shown in Figure 2.
[0016] With reference now to Figure 6, the internal features of the housing can be seen
more clearly. The terminal receiving cavities 54 are defined by side surfaces 56 and
58 where the side surface 56 is co-planar with the side of the aperture 50 and with
the side surfaces of the ribs 24. Although the side surface 56 is shown, due to the
positioning of the cross-section, it should be appreciated that side surface 58 is
a mirror image of the cross-section shown in Figure 6, and having the same co-planarity.
[0017] With reference now to Figures 4 and 6, the substrate receiving slot 20 can be seen
as extending in a transverse direction across the front face 18 of the housing 4.
The slot is defined by an upper surface 34 and a lower surface 40, and further defined
by a plurality of elongate longitudinal ribs 36 and 42. The ribs 36 and 42 are alternately
spaced according to the location of the terminals as best shown in Figure 4, and help
to align the vertical position of the substrate with the contact portions of the terminals.
With reference again to Figure 2, the housing 4 includes apertures 84 therethrough
for retaining the cam member 100 to the housing body. The apertures 84 are defined
by two cut-out sections 80 and 82 which are laterally offset from one another and
opening in opposite directions. Stated differently, the apertures 84 are created by
two retractable mold parts which, when fully inserted, are flush to one another thereby
forming the openings 84, and when retracted, they form the cut-out sections 80 and
82. With reference now to Figures 2 and 8, a further slot 70 is formed behind the
cut-out 80 and is defined by surfaces 72 and 74. With reference to Figure 8, the webs
27 and 29 are shown, which retain the sidewalls 14 and 16 to the remainder of the
housing body.
[0018] With reference to Figure 2, the cam member 100 includes a cylindrical portion 102
integral with a plate portion 110. The cam member 100 includes a plurality of side
by side individual cam members 106 having arcuate surfaces 104 between each of the
individual cam members 106. The plate member 110 includes an upper 114 and lower 112
surface, and a window 108 aligned with each of the cam members 106.
[0019] With reference now to Figure 9, a terminal 150 is shown as including a horizontal
base section 152 having contact parts 172 and 174 extending therefrom in a vertical
direction and a surface mount portion 176 extending in a horizontal direction from
the base portion 152. The contact parts 172, 174 or 176 can be selectively retained
depending on the type of electrical connection desired to the printed circuit board.
A retention arm 168 extends from the front portion of the horizontal base section
152 and includes a first contact portion 166. A vertical leg 154 extends upwardly
from the horizontal base portion 152 and is continuous through a U-shaped section
156 to a contact arm section 158. A lever arm 162 is continuous with the contact arm
158 and has at its lower section, a second contact portion 164.
[0020] To assemble the connector shown in Figure 2, the cam member 100 is inserted into
the nest area 22 of the housing such that the end sections 116 of the cam member 100
reside within the apertures 84 in the housing sidewalls. As installed, the plate portion
110 of the cam member is rotatable between two positive stops, between the positions
where the lower surface 112 of the plate portion is in contact with the upper surface
32 of the platform 30 and, to a position where the surface 114 of the plate portion
110 is in abutting relation with the slanted surfaces 26 of the housing.
[0021] The terminal is then stamped to the configuration shown in Figure 9 including all
three legs 172, 174 and 176, and with the retention arm 168 and contact portion 166
extending at an acute angle relative to the horizontal base section 152. The terminals
can then be plated to provide an electrically conductive surface at the contact points
164 and 166. It should be noted that when the terminal is stamped into the configuration
of Figure 9, the contact points 164 and 166 are separated a sufficient distance that
the terminals can be adequately plated along the sheared edges of the contacts. Subsequent
to the plating process, the retention arm 168 and contact point 166 are rotated in
the counterclockwise direction (as viewed in Figure 9) until the contact point 166
moves into contact with the opposed contact section 164, and is further rotated until
the contact portion 164 is slightly deflected thereby preloading the opposed contact
portions 164 and 166 together. It should be noted that the section 170 of the terminal
is of a reduced cross section relative to the remainder of the terminal which facilitates
the bending of the terminal at the precise desired location, and without undue stresses
causing cracking. It should also be noted that in the preferred embodiment, the desired
material for use with the terminals is a phosphor-bronze alloy which can accommodate
such bending. In the preferred embodiment of the invention, the plating is tin plating
which has been found to be pliable enough to bend at the section 170 without cracking.
Even if some cracking is present, the point which is rotated, that is about point
170, is remote from the contact area and will not effect the electrical characteristics.
[0022] After the contacts 150 are formed into their prestressed position as mentioned above,
the terminals can be stamped to accommodate either a through hole soldered connection
or a surface mount connection. In the preferred embodiment of the through hole soldered
connector, the soldered leads are staggered to provide a closer center line spacing
of the edge stamped contacts. Thus, while referring to Figure 9, every other contact
150 would include a solder leg 172 whereas the remainder of the alternate contacts
would include a through hole solder leg 174. In the event that a surface mount connector
is desired, then each of the solder legs 172 and 174 are sheared clean of the stamped
terminal and the surface mount lead 176 is retained.
[0023] With the terminals stamped and formed as desired, the terminals 150 are insertable
into the electrical housing as shown in Figure 5. The retention arm 168 is receivable
into the aperture 50 of the housing and interference fit to retain the terminals in
position. Since the retention arm 168 is fixedly mounted within the aperture 50 and
with the edge 178 in contact with the lower surface 51 of the aperture 50 as shown
in Figure 5, the opposed contact portions 164, 166 (Figure 9) will be retained in
a prestressed condition. Said differently, the retention arm 168 will have a tendency,
when not loaded in the housing, to relieve its original prestressed condition, by
rotating in a clockwise direction about pivot point 170. However, the retention arm
168 and the horizontal base section 152 are being rigidly held in a fixed linear position
by the aperture 50 which precludes the relaxation between the two opposed portions
164 and 166.
[0024] The camming feature, as described herein, has proven to be quite advantageous for
use with such small components. For example, the housing shown in Figure 2 has a height
between surfaces 6 and 12 of only 4 millimeters, and the flat flexible cable which
in interconnectable to the connector can vary between 0.1 and 0.3 millimeters, with
the conductive elements on the cable at centerlines of only 0.025 inches. The first
advantage, given the lowest height of the electrical connector, is that an actuator
can be used which does not substantially increase the length of the overall connector.
This has been accomplished by designing the cam member to have a very high mechanical
advantage due to the large rotation angle of the camming member between the two stops
as previously described. In order to achieve this high mechanical advantage, windows
108 are provided in the plate member in alignment with each of the cam members. After
the lever arm 162 passes over the cam surface 106, the lever arm 162 actually passes
through the windows 108 increasing the rotation angle of the camming member, and resultantly,
the mechanical advantage.
[0025] The windows 108 also provide for the second advantage, that when the cam member 100
is rotated to its full upright position to a position where the levers 162 project
through the windows 108 as shown in Figure 4, the spring force on the upper contact
arm 158 due to its deflected position bears on the cam member retaining the cam member
in an upward position. This force holds the cam actuator 100 in position, which also
holds the contacts to a deflected condition poised for insertion of the cable. This
simplifies the ease of insertion of the flat flexible cable given the small space
available for access to these connectors. In fact, this detented position allows for
insertion of the cable with the use of one hand only, which is sometimes all that
there is room for, in these densely filled printed circuit boards.
[0026] A third advantage of the camming feature is that a rib 26 is positioned within each
of the circular sections 104 which in turn positions each of the cam members 106 within
one of the recesses 54 which retains the cam members 106 in side to side alignment
with the lever portions 162 of the terminals. This ensures that the lever portions
are retained within the recesses 54 and in alignment with the cam portions 105.
[0027] As mentioned above, the connector has been designed for either through hole or surface
mounting. When the connector will be used in a surface mount application, a retention
feature 200 is used, as shown in Figures 1, 2 and 7, which is insertable into the
recess 70 and can be latched in place. As best seen in Figure 7, the retention member
200 includes two bifurcate arms 202 where the lower arm has a latching shoulder, which
when in the fully inserted position, can be latched behind a shoulder 204 of the web
29. The retention member 200 includes a foot which can then be soldered to the board
which retains the connector in position on the board. It should also be mentioned
that a through hole post could also be provided extending from the retention member
which is soldered or otherwise latched to the printed circuit board.
[0028] As shown in Figure 11, a shielded version is available, where the same housing is
used for both the shielded and unshielded version. As shown in Figure 11, an optional
shield member 300 can be added to the connector 2, which comprises an upper shield
wall 302 and shielding sidewalls 304. A rear shield wall is also provided which extends
between the upper wall 302 and between the sidewalls 304, although due to the angle
of the isometric view of Figure 11, the rear wall cannot be seen. To retain the shield
to the connector housing 4, two retention arms 308 are provided, which are sheared
away from the sidewalls 304 about shear lines 306. The ends of the retention arms
308 include latching features 310 identical to the latching features 202 (Figure 7),
and can be latched to the latching shoulder 204 as shown in Figure 11. It should be
noted that the availability of the shielding version is quite advantageous, and is
due to the quite efficient design of the electrical connector shown in Figure 1. For
example, due to the very efficient camming member 100, the camming member is very
small dimensionally when compared to the rest of the connector housing. Also, the
camming member only operates in a very small portion of the connector housing, leaving
the rest of the connector housing to be shielded. It should be appreciated that the
shield member shown in Figure 11 could also include such features as through hole
posts which are connectable to ground traces on the printed circuit boards.
[0029] As shown in Figures 12 and 13, although the horizontal version shown in Figures 1-10
is the preferred version, again due to the efficient design of the electrical connector,
a vertical version of the connector is available which can be formed by using the
same housing as the horizontal version. All that needs to be changed is the terminal
configuration as shown in Figures 12 and 13.
[0030] Thus, with the efficient design of the electrical connector, the exact same housing
can be used with several differently configured systems. For example, the cam member
of the electrical connector is very small relative to the remainder of the connector
due to the high mechanical advantage of the connector. Furthermore, the connector
can be configured as a horizontal through hole version, a horizontal surface mount
version, a vertical through hole version or a vertical surface mount version. Also,
the terminals are designed such that the same stamping for the horizontal version,
and the same terminal stamping for the vertical version can be used to make either
the through hole or surface mount connector. Finally, any of the above mentioned configurations
can be electrically shielded.
1. In an electrical connector for an electrical connection between a substrate (210)
having printed circuits thereon, and to further conductive elements (202), where the
connector (2) includes an insulating housing (4) comprising a plurality of terminal
passageways (56) for receiving a plurality of edge stamped electrical terminals (150),
and where the electrical terminals (150) have opposed contact members (164, 166) which
effect the electrical connection with the further conductive elements (202), a method
of manufacturing the terminals (150) is characterized by the steps of:
edge stamping the terminals (150) to provide a horizontal base portion (152) with
a spring arm (158) extending upwardly from the horizontal base portion (152), and
an extension arm (168) extending from the horizontal base portion (152) at an acute
angle relative to the horizontal base portion (152) and in an opposite direction from
the spring arm (158), the extension arm (168) having a first contact member (166)
extending upwardly therefrom towards the spring arm (158), and the spring arm (158)
having a second contact member (164) thereon, which is spaced from the first contact
portion (166); and
subsequently bending the extension arm (168) towards the spring arm (158) to position
the first (166) and second (164) contact portions in an opposed and facing relation.
2. The method of claim 1 characterized in that subsequent to the edge stamping, but
prior to the bending of the extension arm (168), the first (166) and second (164)
contact members are plated.
3. The method of either of claims 1 or 2 characterized in that the extension arm (168)
is bent into the spring arm (158) in a dimension which preloads the first (166) and
second (164) contact portions against each other.
4. An electrical connector for use with any of the claims 1-4 characterized in that
the housing (4) has a plurality of apertures (50) extending in the housing (4), where
the extention arms (168) may reside.
5. An electrical connector according to claim 4 characterized in that a substrate
receiving slot (20) is integral with the housing (4) and extends above and transverse
to the apertures (50).
6. An electrical connector according to any of the claims 1-5 characterized in that
the terminal receiving passageways (56) are defined by a floor (51) which extends
forwardly to the apertures (50).
7. An electrical connector according to any of the preceding claims characterized
in that the lower edge (178) of the horizontal base portion (152) is in abutment with
the floor (51).
8. An electrical connector of any of the preceding claims characterized in that each
of the terminals (150) includes a weakened section (170) between the horizontal base
portion (152) and the extension arm (168) to facilitate bending.
9. An electrical connector of any of the preceding claims characterized in that the
floor (51) extends behind the weakened section (170) of the terminals (150).
10. An electrical connector of any of the preceding claims characterized in that the
upper edges of the extension arms (168) are in abutment with the upper surfaces of
the apertures (50), thereby preventing anti-rotation of the extension arm (168) relative
to the horizontal base section (52).