Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
-- 1 --
CONNECTUR FOR PRINT~D CIRCUIT BOARDS FOR EFFECTING
A RESILIENT PRESSURE CONTACT ~ITH AT LEAST ONE CONDUCTIVE SURFACE
Jhe present invention concerns a connector for printed circuit boards
for effecting a resilient pressure contact with at least one conductive
surface on at least one face of a rigid structure, said connector
comprising :
S - a housing having guiding means for directing the rigid structure
along a path in an insertion direction,
- and at least a resilient contac~ located in the housing and having a
first end portion initially positioned in said path, and movable along
said path, a second end portion integral with a connexion means mounted
on said housing, and a central part positioned outside said path,
- said first end portion comprising means for being displaced with said
rigid structure moving along said path in said insertion direction, in
such a manner to incurve said contact and to create a rolling pressure
against the conductive surface on the rigid structure.
~rench patent application 2,395,676describes a connector Or this type,
in which the resilient contact has the form of a conductive metal blade9
whose resilience creates sufficient pressure, exerted by the rounded
part of this blade on the conductive surface of the rigid structure, in
order tc ensure gooo elertrical contact between the two conductive
parts.
However it has been noticed that in practice this contact pressure is
too week, because soft coatings, for example tin-lead electrolytic coat~
ings, do not give homogeneous contact resistance. These defects become
notably serious when the device is submitted to vibrations. ~n increase
of the thickness of the blades diminishes their flexibility and causes
them to break.
An object of an aspect of the invention is to ~void the above mentionedinconveniences by making a connector such as that defined previously,
in which the contact comprises at least one resilient blade made from
electrically good conductive material, and at least a spring component
34 made frrm material having good elasti~ properties, the said spriny
- 2 J~ 3
-
component being adapted to lean against the said resilient blade in
order to ensure substantially constant elastic pressure nf the said
central portion of the resilient blade against the conductive surface.
According to an aspect of the invention, the contact blade is fixed
by one of its ends to the said connexion means. The preferred fixing
method is soldering, notably soldering by points effected by laser.
For connecting printed circuit boards provided with a series of parallel
conductive tracks, constituting the said rigid structure comprising a
series of conductive surfaces, the connector according to the invention
comprises preferably a series of contacts, each provided with a resi-
lient blade made from electrically good conductiYe material, and a
spring component, preferably a blade made from material having good
elastic properties, the said resilient blades and said spring blades
being respectively parallel to each other, each spring blade comprising
a resilient blade, these two elements constituting a couple of elements
which co-operate to ensure substantially constant elastic pressure and
good electrical contact of each resilient blade on the corresponding
conductive surface of the rigid structure.
Accord~ng to an aspect of the invention, the connexion means
and spring blade are made from one piece. The lower part of this piece
constitutes the connexion means which may appear under different known
specific forms. The upper part of this piece constitutes the spring
blade to which is fixed the contact bladeO
In certain cases, notably when the number of couples : connexion means
conductive blades is high, the assembly by soldering by laser can be
complicated due to difficulties in placing low dimension pieces which
are fragile, which stick together and whose handling is thereby extre-
mely delicate.
~lith the airn of sirnplifying assembly workl the connector according to
anothcr objcct of thc prescnt invcntion is ch-lractcri7ed in that the
contact cornprises a resilicnt insulating support in strip form, at lcast
37 one mctal track applicd on onc face of thc said support, the spring
_ 3 _
means being adapted to lean against the D~her face Df the said insulat-
ing support, in such a way as to apply the said central portion of the
said contact, with a substantially constant pressure, against the said
conductive surface of the said rigid structure.
According to a particularly advantageous embodlment of the present
invention, the conductive track comprises an electrically good conduct-
ive metal blade, integral with the said support. The conductive track
consists preferably of a blade made from a copper material, covered on
its free surface, by a protective layer~ made for example, out of a
tin-lead alloy applied by a known galvanic process.
The insulating support is preferably a sheet of synthetic material, for
example, of a polyimide type. The thicl<ness of the insulating support
and the conductive blade is such that the whole is extremely resilient
and flexible in order that the conductive track leans firmly against
the conductive surfaces of the rigid structure.
According to a preferred embodiment of the invention, the connector com-
2û prises a series of conductive tracks corresponding respectively to a
series of conductive surfaces of the rigid structure, these tracks be-
ing placed parallel on a face of the insulating support strip, and a
collection of spring blades adapted to apply individually the central
portions of the said conductive tracks, with a substantially constant
pressure, on the conductive surfaces of the rigid structureO The conduc
tive tracks are preFerably connected electrically to the connection
means integral with the housing by crimping.
The spring means, which are preferably parallel blades9 are preferably
3û attached by their base to a continuous transversal strip in such a WBy
that a comb structure is obtained. The upper free ends of these blades
comprise a swelling intended to lean against the central portions of
the conductive tracks of the rigid structure.
~Jhen the flat rigid structure comprises conductive tracks on its two
opposed flat faces, the spring blades are adapted to form a double comb
37 structure, the blades being placed on two rows parallel to each other
-- 4 ~
and being attached by their base to a continuous transversal ~trip,
which comprises means for fixing this double comb inside the housing,
in the extension of the said path in the insertion direction of the
rigid structure.
The contact comprises a supple strip portion having, before being
mounted in the housing, a form appreciably rectangular, comprising two
opposed series of conductive tracks parallel to each other, the strips
of one series being separated from those of the other by an insulating
zone, this strip being folded in "M" shape to be introduced into the
housing, the free ends of the two arms of the M being connected by
clamping to corresponding connection means, and the insulating means
being placed in the central part of the M, and surrounding the end o
the runner which moves along said path du~ing insertion of the rigid
structure.
The present invention and its principal advantases will be better under-
stood with reference to the description of a different embodiment there-
from and to the various drawings on which :
~0
Figure 1 represents a schematic view of a first embodiment oF the
connector according to the invention, before introduction of a printed
circuit board,
Figure 2 represents the connector of figO 1 when the printed circuit
board is in place,
Figure 3 represents a flat view of a second embodiment of the connector
according to the invention, before insertion of the rigid structure,
Figure 4 represents a flat view of the connector according to fig. 3,
after inSertiDn of the rigid structure, and
Figure 5 represents a flat view of the insulating support and the metal
tracks of the contact.
37 ~Jith reference to figures 1 and 2, the connector described includes a
_ . _ _ _
i3
-- 5 --
housing 1 at the base of which are mounted two series of connexion means
2 and 3, intended to be connected to the conductive tracks ~ and 5 of a
printed board 69 by means of contacts which will be described in more
detail below.
These contacts are made up essentially of a supple blade 7, respectively
8, and a spring blade 9, respectively 10. The supple blades 7 and 8 are
made from an electrically good conductive material such as copper or
its alloys, and comprlsing an outside layer 11, respectively 12, of a
lû protecting material such as a tin-lead alloy. The spring blades 9, res-
pectively 10, comprise a swelling 13, respectively 14, by which they
apply a substantially constant pressure on the inside surface of the
conductive blade 7, respectively 8. The opposed ends oF the spring
blades 9 and 10 are respectively connected to the connection means 2
and 3. According to a preferred embodiment, the spring blades and
corresponding connection means are made from one piece. The supple
conductive blades 7 and 8 are fixed, preferably by soldering by points
by laser (see references 15 and 16) to a branch appreciably rectilinear
o~ the corresponding spring blade 9, respectively 10. When the spring
blades are not made from one piece with the corresponding connection
means, the conductive blade can also be joined to a branch of the cor-
responding connection means. The other end of the conductive blades 7,
respectively 8J is pre~erably fixed, by any appropriate means~ notably
by soldering by points by laser (see references 17 and lB), to the
lateral walls of a runner 19, capable of adopting two positions repre-
sented respectively by figures 1 snd 2.
Connection means 2 and 3 comprise respectively an elastic tongue 20 and
21, intended to slide under shoulders 22 and 23 provided in a wall de-
fining the interior cavities of the housing 1. The connection means canbe introduced at the too of the housing 1~ until these elastic tongues
slip under the corresponding shoulders 22 and 23.
When printed circuit board 6 is introduced, runner 19 is pushed down
until it is in the stop position against the base of housing 1. During
insertion of the printed circuit board in the passageway 24 provided in
37 housing 1 and whose lateral walls serve as guiding means, the conductive
-- 6 --
blades 7 and 8 are applied without friction against the metal tracks 4
and 5 of printed circuit board 65 unoer a substantially constant press-
ure due to resilient pression of the swellings 13 and 14 DF the spring
blades 9 and 10.
Thanks to this device, is thus solved the problem set by the prior art,
by ensuring resilient support with a-substantially constant pressure of
the conductive blade on the metal tracks of the printed circuit board.
Printed circuit boards 6 comprise in general a series of parallel metaltracks, placed on each of these two flat faces. To ensure contact with
these differen~ tracks, the connector comprises a series of couples
each made up of a conductive blade 7 (respectively 8) and a spring blade
9 (respectively 10), each one of these couples being respectively asso-
ciated with connection means 2 and 3. These couples of elements togetherconstitute a double series of contacts which assure electric contact
between the double series of connection means and the double series of
metal tracks of the printed circuit board.
2û With reference to figures 3 to S, the connector described represents a
housing lûl containing at least one contact adapted for ensuring contact
between connection means lOZ and 103, and metal tracks 104 and 105 of a
flat rigid structure constituted for example of a printed circuit board
106.
The contact is made up, in the present case, of a supple insulating
support 107 cornprising at least two metal tracks 108 and 109 placed on
the exterior surface of the said supple support, and two spring blades
110 and 111 joined to their base by a central transversal strip 112.
In practice, the printed circuit board comprises a series of parallel
tracks lû4 on one of its faces, and a series of parallel tracks 105 on
its opposed flat face. To ensure contact respectively with each of
tracks 104 and 105, the supple insulating support 107 comprises a first
series of rnetal tracks 10~ parallel to each other and a second series
of rnetal tracks 109, equally parallel to each otller and parallel to
37 tracks 10~ of the first series. To each track 108 corrcsponds a spring
-- 7 --
blade 110 and to each track 109 corresponds a spring blade 111. Each
one of these blades is joined by its basP to the continuous transversal
strip 112, which comprises a series of openings 113 intended to be
fixed to the body 101 uf the connector, for example by rivets 114. The
collection of the sprinc3 blades 110 and 111 presents a double comb
structure.
If the printed circuit board comprises only one series of metal tracks,
the double comb structure could be replaced by a simplified structure9
comprising only one series of spring blades 110 or 111.
The upper ends of the connection means 102 and 103 comprise crimping
means 115 and 116 already known, comprising crimping means capable
of crossing the insulating support 107 and producing electric contact
with the corresponding metal track 108 or 109.
The housing 101 comprises, in its centre, a passageway 117, whose late-
ral walls constitute guiding means which direct the printed circuit
board 106 according to a fixed path in its insertion direction into
the housing. A runner llB, describedinmore detail in theabove~renchappln.
is permanently introduced in the passageway 117 and moves between a
first position trepresented by figure 3~ and a second position (repre-
sented by figure 4). In the first position, the printed circuit board
106 is being inserted in the connector. In the second position9 this
board is totally inserted in the co~nector9 and contact is established
between tracks 104 and 105, respectively with the connection means 102
and 103, through the intermediary of the respective metal tracks 108
and 109.
Thanks to swellings 119 and 120 of the upper ends of the spring blades
110 and 111, metal tracks 108 and 109 are applied9 with a substantially
constant pressure, against the metal tracks 104 and 105 of the printed
circuit board 106. As support 107 of the metal tracks 108 and lD9 is
insulating~ the spring blades 110 and 111 can be joined to cach other
without risking a short circuit bctween the metal tracks of tile same
36 series (104 or 105~ or the two series (104 and 105~.
As in the device described in the above mentioned French application,
the metal tracks 108 and 109, which constitute the contact blades, roll
without friction on the corresponding metal tracks 104 and 105 of the
printed circuit board.
Figure 5 represents a flat view of the insulating support 107 compris-
ing, on its outside surface, a first series of metal tracks 108 parallel
to each other, and a second series of metal tracks 109 parallel to each
other and, in the present case9 placed in the extension oF the metal
tracks 108. The two series of tracks 108 and 109 are separated by a
neutral insulating zone 121. The production of metal tracks 108 and 109
is carried out by a photochemical procedure9 identical to the techniques
used for producing printed circuits. The supple support 121 is prefer-
ably made of a synthetic material of the polyimide family.
When placing the insulating support 107 carrying the metal tracks 108
and 109 in the housing 101 of the connector 9 the supple strip is folded
into an "M" shape, in such a way that the neutral zone 121 corresponds
to the lower end of the runner 118, and that the respective ends of the
metal tracks 108 and 109,opposite the neutral zone 121, correspond to
the crimping means 115 and 116 of the connection means 102 and 103.
The metal tracks 108 and 109 are preferably made of copper or copper
alloy covered with a layer of protective tin-lead alloy.
Of course different production variants can be foreseen. Notably, metal
tracks 108 and 109 can be arranged differently in order to be adapted
to an arrangement corresponding to metal tracks 104 and 105 of the
printed circuit board lû6. Moreover the ends of metal tracks lû8 and
109 could be connected by different means from connection means 102 and
103. Nevertheless, the realization such as that described seems to be
that which gives the best results for relatively modest manufacturing
33 costs~ and relatively easy assembly conditions.
