[0001] This invention relates to an electrical edge connector for a printed circuit board,
ceramic substrate or the like and is particularly concerned with providing the so-called
LIF, low insertion force or ZIF, zero insertion force function in such a connector.
[0002] LIF or ZIF functions are desirable in multi-way connectors to reduce engagement and
disengagement forces between mating connectors. It is known to provide connectors
which can be engaged or disengaged with complementary contacts disengaged so that
there is no abrasive engagement of the contact surfaces during connector housing engagement.
Contact engagement is then effected by relative movement of complementary contacts,
for example, by a cam member moveable on the connector housing.
[0003] The avoidance of abrasive engagement between contacts of an edge connector and a
printed circuit board or substrate is particularly important where edges of the board
or substrate may be sharp, due to their manufacturing process, since the sharp edges
may severely damage the contact surfaces. For example, ceramic substrates may be cut
to size by laser with resultant sharp edges at the cut portions.
[0004] It is an object to provide an edge connector which may be engaged with the edge of
a board or substrate without initial engagement of the contact surfaces with the board
or substrate edges and which avoids the need for additional members to the housing
and contact or contacts and is economic to produce.
[0005] According to the invention an edge connector for a printed circuit board or substrate
comprising an insulating housing formed with a contact receiving through cavity and
a slot for receiving the board or substrate traversing the cavity at one end, the
contact having a pair of spring arms with free ends presenting contact surfaces disposed
at opposite sides of the slot for engaging opposite sides of the board or substrate,
is characterized in that the contact is moveable within the cavity in the insertion
direction of the board or substrate between a first condition in which the contact
surfaces are disposed outside opposite sides of the slot, and a second condition in
which they are disposed within the slot width.
[0006] Suitably the contact has a portion disposed between the spring arms and which, in
the first condition, projects into the slot, whereby engagement of the connector with
the board or substrate edge registers the projecting portion with the edge to effect
movement of the projecting portion rearwardly of the slot and movement of the contact
to the second condition.
[0007] The projecting portion is suitably formed with a spring extension engaging a ramp
surface formed on a wall of the cavity and arranged to bias the contact towards the
first condition.
[0008] Movement of the contact between the first and second conditions is suitably limited
by stops formed in the cavity.
[0009] The contact is suitably formed with divergent spring arms, and the cavity is of reduced
width, rearwardly of the slot, whereby on movement of the contact between the first
and second conditions, the spring arms are constrained together, by the reduced width
cavity portion, to enter the contact surfaces into the slot.
[0010] The invention also includes a contact in or for a connector according to the invention
which comprises a channel shaped body, sides of the channel being extended, at one
end to define a pair of spring arms with opposed contact surfaces, characterized in
that the base of the channel shaped body is formed with an extension projecting forwardly
between the arms to a position rearwardly of the contact surfaces.
[0011] The extension of the base is suitably folded back at a rearward inclination as a
spring arm with its free end spaced from the base of the channel portion between the
channel sides.
[0012] Suitably the spring arms formed with the contact surfaces diverge away from the channel
shaped body.
[0013] The invention will now be described, by way of example, with reference to the accompanying
partly diagrammatic drawings, in which:-
Figure 1 is an elevation of a connector housing from one side;
Figure 2 is a section taken on the line 2-2 of figure 1;
Figure 3 is an elevation of the connector of figure 1 from the opposite side with
an end cavity shown in section;
Figure 4 is a plan view of the connector of figure 1;
Figure 5 is a side elevation of a contact for the connector of figures 1 to 4, but
to an enlarged scale;
Figure 6 is a plan view of the contact of figure 5;
Figure 7 is a sectional view of a cavity of the connector viewed from an opposite
direction to that of figure 2, and containing a contact according to figures 5 & 6,
and in an initial condition of engagement with a substrate;
Figure 8 is a section taken on the line 8-8 of figure 7, viewed in the direction of
the arrows;
Figure 9 is a view similar to that of figure 7 but with the substrate fully engaged
with the connector, and
Figure 10 is a view similar to that of Figure 8 but with the contact in a condition
similar to that of figure 9.
[0014] The connector housing of figures 1 to 5 is formed of resilient plastics insulating
material as a unitary molding, and comprises a connector body portion 1 of generally
rectangular slab-like form having at one major face, a mounting and retention section
2. The body 1 is formed with five through cavities, 3 arranged in a row and with a
slot 4 for receiving a substrate edge extending transversely of the cavities 3 between
opposite sides of the body 1, at a lower end as seen in figure 2. At the upper end
on a face opposite the mounting section 2, the body 1 is formed with a flap 5 extending
from side to side of the body across all of the cavities 3 and integral with the body
1 at a hinge 6 at a middle portion of the body between upper and lower ends thereof.
The flap 5, at its upper edge is formed with a series of latch projections 7, each
having a latch aperture 8 and arranged to project transversely over walls 9, separating
the cavities 3, the apertures 8 engaging projection 10 formed on walls 9 to secure
the flap 5 in the position shown.
[0015] It will be understood that the flap 5, with the latch projecting 7 disengaged from
wall projections 10, is moveable by bending at the hinge 6 between an open position
at 90 degrees counterclockwise from the position shown, to the closed portion shown.
[0016] The flap 5 is formed adjacent the hinge 6, and internally of the cavities 3, with
a series of inwardly projecting shoulders 11, one to each cavity 3, the shoulders
having downwardly facing shoulder surfaces for contact retention purposes as will
be described later in connection with figures 7 to 10.
[0017] Each cavity 3 is formed substantially at the level of hinge 6 and on one of the cavity
sides bridging the slot 4 with an inward projection 12 having upper and lower ramp
surfaces 13, 14 for camming engagement with a portion of a contact as will be described
later. On the opposite side of each cavity there is formed a shallow groove 15 extending
upwardly from the mouth of slot 4, beyond slot 4 and terminating opposite the projection
12 in a downward facing shoulder 16 for contact retention purposes as will be described
later. These sides of each of the cavities are formed adjacent the other pair of sides
with shallow projections defining upward facing shoulders 17 slightly above the level
of the slot 4, which serve to limit contact insertion. The other pair of sides, below
the shoulders 17 diverge to a lower cavity portion surrounding the slot 4, of enlarged
width, as seen in figure 2.
[0018] The mounting section 2 comprises a pair of spaced latch arms 18 depending from a
bridge portion 19 stood away from the body 1. The arms 18 are of channel form open
sides of the channels facing outwards as seen in figures 1 and 4, and lower ends of
the channels being closed by latch portions 20 having upper and lower ramp surfaces.
It will be understood that the lower ends of the arms can be resiliently flexed together
to enable engagement or disengagement of the latch projections 20 with complementary
means on a fixture for releasably securing the connector to the fixture.
[0019] The contact of figures 5 and 6 comprises a channel shaped middle portion 21 having
at one end a wire connecting section 22 of conventional form comprising a U-shaped
wire crimp ferrule 23 and insulation support ferrule 24 extending from a carrier strip
25. At the other end of the portion 21, opposite sides of the channel are extended
in divergent manner, as spring arms 26, to free ends which are turned inwards in arcuate
manner to present opposed arcuate contact portions 27. As seen in figure 5 in side
elevation the spring arms 26 are progressively reduced in width towards the free ends.
[0020] The base of the channel shaped portion 21 is formed between the arms 26 with an extension
28 which, as seen in figure 6, is reduced in width forwardly and is stiffened by a
central embossment 29. The extension 28 is further extended by a bent back portion
30 which extends rearwardly and upwardly between the arms 27 to project at its free
end 31 above the channel portion 21. The free end 31 is bent down in arcuate manner
to present an upwardly convex engagement surface.
[0021] The base of the channel portion 21 is formed with a downwardly and rearwardly extending
retention latch 32 pushed out of an aperture in the base behind the embossment 29.
[0022] In use the contact of figures 5 and 6 is severed from the carrier strip 25 and crimped
to a stripped wire end 33 in conventional manner to present a terminated lead for
assembly to the connector housing of figures 1 to 4 as shown in figures 7 to 1
0. In figures 7 and 9 the mounting section 2 of the connector housing is not shown.
For assembly of terminated leads to the connector housing, the flap 5 is moved to
an open condition so that the projections 11 are clear of the cavities 3. The contacts
are inserted into respective cavities 3, leading ends of the contact springs 26 initially
engaging opposite sides of the cavities 3 below the hinge 6 arid thereby flexed inwardly
to allow passage into the cavities until the retention latch 32 enters the groove
15 and engages the shoulder 16 to secure the contact against withdrawal from the housing.
During the insertion the free end 31 of the extension 29, 30 engages the ramp surface
13 to flex the extension 30 inwardly until the free end 31 engages the ramp surface
14. At this condition, which corresponds to figures 9 and 10, the spring arms 26 are
constrained inwardly by the cavity walls, and shoulders 34 at the lower end of the
channel section 21 on opposite sides of the extension are spaced above the housing
shoulders 17. The contact is thus capable of further downward movement through the
cavity 3 and the flexure of the extension 30 against the ramp surface 14 exerts a
downward force on the contact to move it downwardly until the shoulders 34 and 17
engage to resist further downward movement. The contact is now in the condition of
figures 7 and 8.
[0023] In this condition the spring arms 26 enter the lower cavity portion of increased
width and flex apart on opposite sides of the slot 4 with the contact ends 27 outside
the slot 4. The forward or lower end of the extension 28 is disposed within the slot
4, and the retention latch 32 is spaced below the shoulder 16.
[0024] When all of the contacts have been assembled into respective cavities 3, the flap
5 is closed to the condition shown in figures 7 and 9 so that the projections 11 enter
respective cavities behind and above the channel sections 21 in a position to register
with rear or upper edges of the channel sections 21 as shown in figures 9 and 10 to
provide a secondary contact retention to that provided by latch 32 and shoulder 16.
[0025] In the condition of figures 7 and 8, the connector can be assembled to a substrate
35 by entering the edge of the substrate 35 into the slot 4 between the contact ends
27 until the edge of the substrate 35 engages the forward lower end of the contact
extension 28. In this position, shown in figure 7, the contact ends 27 are clear of
the slot and are not engaged by the substrate 35, so that risk of damage of the contact
surfaces by sharp edges of the substrate 35 and by abrasion is avoided. Further movement
of the substrate 35 into the slot 4 drives the contact upwardly or rearwardly in the
cavity 3, the extension 30 being flexed inwardly by the ramp 14 and the spring arms
26 being flexed inwardly by being drawn into the cavity portion of reduced width.
The contact ends 27 are thus urged against opposite sides of the substrate, as shown
in figure 9 to exert contact force.
[0026] The substrate 35 is suitably supported in a fixture, now shown, having means complementary
to the latch arms of the mounting section 2 of the connector so that the latch arms
18 at their ends 20 engage the complementary means in a snap fit releasably to secure
the connector in the condition of figures 9 and 10. To release the connector, the
latch arms 18 may be flexed together, and the connector withdrawn from the substrate
35 by upward movement of the housing in the figure 9 position to that of figures 7
and 8. The spring extension 30 and the engagement of its free end 31 with the ramp,
serves to drive the contact downwards relative to the housing so that the contact
ends 27 flex apart from the substrate to the figure 7 condition before the connector
is withdrawn from the substrate 35. In this way abrasion of the contact ends 27 with
the substrate 35 and engagement with any sharp edges is avoided.
1. An edge connector for a printed circuit board or substrate comprising an insulating
housing (1) formed with a contact receiving through cavity (3) and a slot (4) for
receiving an edge of the board or substrate (35) traversing the cavity (3) at one
end, the contact having a pair of spring arms (26) with free ends presenting contact
surfaces (27) disposed at opposite sides of the slot (4) for engaging opposite sides
of the board or substrate (35) characterized in that the contact is moveable within
the cavity (3) in the insertion direction of the board or substrate (35) between a
first condition (figs. 7&8) in which the contact surfaces (27) are disposed outside
opposite sides of the slot (4), and a second condition (figs. 9&10) in which they
are disposed within the slot (4) width.
2. A connector as claimed in claim 1, characterized in that the contact has a portion
(28) disposed between the spring arms (26) which, in the first condition, projects
into the slot (4) whereby engagement of the connector with the board or substrate
edge (35) registers the projecting portion (28) with the substrate edge (35) to effect
movement of the projecting portion (28) rearwardly of the slot (4) and movement of
the contact to the second condition.
3. A connector as claimed in claim 2, characterized in that the projecting portion
(28) is formed with a spring extension (29) engaging a ramp surface (14) formed on
a wall of the cavity (3) and arranged to bias the contact towards the first condition.
4. A connector as claimed in any preceding claim, characterized in that stops (16,11,17)
are formed in the cavity (3) to limit movement of the contact between the first and
second conditions.
5. A connector as claimed in claim 1, characterized in that the contact is formed
with divergent spring arms (26) and the cavity (3) is of reduced width rearwardly
of the slot (4) whereby on movement of the contact between the first and second conditions
the spring arms (26) are constrained by the reduced width cavity portion to move together
to enter the contact surfaces (27) into the slot (4).
6. A contact in or for a connector as claimed in claim 1 and which comprises a channel
shaped body (21) sides of the channel being extended at one end to define a pair of
spring arms (26) with opposed contact surfaces (27), characterized in that the base
of the channel shaped body (21 ) is formed with an extension (28) projecting forwardly
between the arms (26) to a position rearwardly of the contact surfaces (27).
7. A contact so claimed in claim 6, characterized in that the extension (28) at its
forward end is folded back at a rearward inclination as a spring arm (30) with its
free end (31) spaced from the base of the channel portion (21) between the channel
sides.
8. A contact as claimed in claim 6 or 7, characterized in that the spring arms (26)
diverge away from the channel body (21).