Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
59-13~ 99
MArrERi~L F~R ELECTRIC CONTACTS
This invention relates to a material for
for~ing electric contacts whlch are used in connectors,
switches, relays or the like for electronic equipment
and which are inexpensive and have high conductivity
05 and spring:iness which could not be achieved by nowadays
widely used copper alloys such as phosphor bronze.
In these days, there is generally a -tendency
for articles or goods substantially in all fields to
become lighter, thinner, shorter and smaller to fulfil
the requirements in the presen-t age in view of economy
and saving of resources. In elec-tronic products,
par-ticularly, manu~acturers endeavor to make srnall-sized
and high-performance products. In order to fulfil the
requirements, it is essential to realize -the minia-turiza-
tion of parts including contacts such as connectors,switches and the like a great number of which are used
in the electronic equipmen-t, thereby enabling these
parts to be applied into the electronic appliances in
highly compacted manner. However, it is almost impossible
for the contacts rnade of presently widely ~Lsed copper
alloys to realize -the miniaturization of the parts
including the contacts to remarkable extents.
In more details, the contacts for use in
connectors, switches and the like are required to have
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high conductivity ancl springiness in their nature.
ITI gene:ral! however, metals l1aving the higher cond-uc-tivity
are e~hibit the lower springiness, while metals having
the higher springiness exhibit the lower cond-uctivity.
05 There has been no metal fulfiling the -two req-uirements,
that is, the high conductivity and springiness simul-
taneously.
Therefore, copper alloys such as phosphor
bronze are generally usecl, which fulfil the above
requirements to a certain extent with which al-though
dissatisfied. ~lowever, even such a copper alloy which
is generally recognized to be most suitable :Eor this
purpose has only a much lower conductivity than that of
pure copper and silver. In order to ob-tain contacts of
high conductivity having the required springiness,
therefore, sectional areas of the contacts should be
made large to improve their conductivity, so -that the
contacts unavoidably become large. Accordingly 3 the
miniaturization of contacts would encounter a limitation
due to these factors. ~oreover, copper alloys to be
used as spring materials are generally not only very
expensive but also very -troublesome in production
processes, inasmuch as they need high accuracy heat
trea-tment by precisely con-trolling temperature, time
and atmosphere. Contac-ts made of swch alloys are
naturally expensive.
In order to eliminate the above disadvantages,
it has been attempted to joint or laminate a high
~ ~5 ~
springiness met~l an(l a hi~h conduct:iv:ity metal by
pressure welding, electrolytic process or vapor
deposition to obtain contacts having high conductivity
an~ springiness. ~lowever, the contacts thus obtained
05 have the following disadvantages which are not adopted
in practical use. For example, w:ith this method directly
jointing the different metals, diffusion between them
progresses step by step with the lapse of time to
change compositions and conditions of the metals, so
that the initial characteristics of the metals change
so as to lower the performance of the contact. In case
that a stainless steel is used as a spring material and
is coated thereon with silver, copper or gold having
high conductivity, oxide films on the stainless steel
for preventing its rust should be removed in order to
ensure the coating of the conductive metal. Therefore,
the superior corrosion-resistance of the stainless
steel is los-t to cause serious corrosion when p;in-holes,
cracks or -the like occur in -the coating metal. In this
case, electric potential of the stainless steel is
quite different from that of the copper, silver or
gold, so that there is a risk of electrochemically
promoting the corrosion of the stainless. ~or example,
moreover, the composite body consisting of the two
different metals closely jointed sometimes encounters a
difficulty in that upon variation in temperature the
closely contacted metals tend to separate from each
other so as to break due to thermal stresses resulting
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from ~he di~`ference in their coefficient of thermal
e~pansion.
tt is therefore impossible for the contacts
of the prior art to realize the miniaturization and low
05 cost of connectors or the like and to improve the
performance of the existing con-nectors or the like.
Moreover, it is almost impossible to reali7e the
miniaturiz~tion and low cost of electronic appliances
by very cornpactly arranging therein the connectors or
the like. It is therefore eagerly expected to realize
contact fulfiling the above re~uirements.
It is a principal object of -the invention to
provide an improved electric contact forming material
which elim-inate all the disadvantages of the prior art.
In order to achieve this object, the electric
contact forming material according to the invention
comprises a first metal layer for providing a conduc-
tivity, a second metal layer for providing a springiness
and a plastic layer interposed between the irst and
second metal layers to form a lamina-ted material.
In a preferred embodiment, the plastic layer
has insula-ting property or conductivity.
In another embodiment, at least one of the
first and second metal layers consists of at least two
layers, between which a plastic layer is interposed.
Either one of the first and seconcl metal layers
consists of two metal layers which are arranged on one
side of the other of the first and second metal layers
~s~
or arrangecl one on each side of the other metal layer.
In a Eurther embodiment, at least one of the
~irst and second metal layers is at 1east partially
provided with a coat:ing layer by metal plating, chemical
05 treatment or coating with an oil, a paint or a coating
agent in order to improve environment-resistance,
wear-resistance, stability of electric connection,
weldability, solderability or -the :Like.
The invention will be more fully wnderstood
by referring to the following detailed specification
and claims taken in connection with the appended drawings.
Fig. l is a sectional view illustrating the
principal constitution of the contact forming material
according to the invention;
Fig. 2a is a perspective view of one strip
cut from the contact forming material according to the
invention;
Fig. 2b is a perspective view of the strip
shown in Fig. 2a, which has ~een formed into a contac-t;
Fig. 3 is a perspective view of a contact
forming material according to the invention;
Fig. 4 is a sectional view of a connector
using contacts made from the material shown in Fig. 3;
Fig. 5 illustrates various shapes of contac-ts
(a~-(Q) formed from the material shown in Fig. 3;
Fig. 6a illustrates a contac-t forming material
according to the inven-tion, -formed with a number of
first metal layers by etching;
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~ ig. 6b is a pers~pective view :illustrating
the contact :forming material shown in Fig. 6a, which
has been foldecl;
Fig. 6c is a perspective view of a male
05 connector including the folcled material shown in Fig. 6a;
Fig. 7a illus-trates two contac-t forming
materials ~or forming a female connector;
Fig. 7b is a perspective view illustrating
the material shown in Fig. 7a which is forrned so as to
e~tending a contacting portion;
Fig. 7c is a perspective view illustrating
male and female connectors made from the materials
shown in Figs. 6a and 7a;
Fig. 8 is a sectional view of the connector
consisting of the male and female connectors shown in
Figs. 6c and 7;
Fig. 9a is a sectional view illws-~rating a
fwrther embodiment of the material according to the
invention including one metal layer consisting of two
metal layers which are arranged on one side of the
other metal layer; and
Fig. 9b is a sectional view illwstrating a
still further embodiment of the material according to
the inven-tion inclwding one metal layer consisting of
two metal layers which are arranged one on each side of
the other metal layer.
Fig. 1 illwstrates in section one embodiment
of a material for forming a con-tac-t according to the
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invent:ion. This material. essentially comprises a first
metaL l.ayer l having a desirecl cond~ctivity and a
second ~etal layer 2 having a required springiness
selected from the existing metals and a plastic layer 3
05 interposed therebetween for supporting the two laminated
metal layers 1 and 2 one above the other. This composite
material is produced in the following manner.
One metal havi.ng a required cond-uc-tivity for
forming the first metal layer 1 is selected from a
group of the existing metals such as copper, silver,
gold, aluminium and the :Like and alloys of these metals.
Then, one metal having a required spring force fo:r
forming the second metal layer 2 is selected from a
group of the existing metals such as iron alloys as
spring stainless steel, copper alloys as spring beryllium-
copper alloy, a metal containing spring reinforcing
agent such as whisker and the like, amorphous metal and
the like. These metals are formed in pla-tes, strips or
foils according to required current capacity, spring
force, shapes of the con-tact to be made, manufacturing
method and the like. ~etween the thus formed metals 1
and 2 is attached a plate or sheet like plastic material. 3
having a required thickness coated with -thermoplastic
or heat bonding adhesive by heating and pressure welding
or with the aid of a rubber adhesive or polymerization
setting adhesive. ~he plastic material may be, for
example, epoxy, polyester, polyimide, polyamide or
polyolefin resin. As an alternative, on the plastic
layer 3 n~ly be ~ormed the ~irst and second metal layers 1
and 2 by means of e'Lectropla-ting, chemicalplating,
vapor deposition or spattering.
In th:is manner, the present invention takes a
05 step out of the prior art attempted to do inherently
impossible matter, that is, to make a single 'body
fulfil both the conductivity and springiness. According
to the invention, there are provided the first metal
layer :L taking charge of the conductivity and the
second metal layer 2 taking charge of the springiness
to effectively utilize the respective characteristics
wi-thout compromising both the conductivity and springi-
ness. ~ccordingly, for example, a contac-t forming
material 4 in a strip shape produced according -to the
invention as showing in Fig. 2a is cut and formed into
a contact S as shown in Fig. 2b which is small-sized
and inexpensive in comparison with those of the prior
art made of the copper alloys under the same current
capacity ancl con-tact pressure. The contacts 5 are -used
for a connector as shown in Fig. 4. Moreover, for
example, a contact forming material 4 in a plate shape
produced according to the invention as shown in Fig. 3
may be cut ancl formed or punched into various shapes of
contacts as shown in Fig. 5(a)-(Q).
Moreover, according to the invention 'between
the first and second metal layers 1 and 2 is securely
held by means of advanced adhesion teehnique the plastic
layer 3 to which required insulating or conductive
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property .-lncl desi~ed pl.iabi:lity or Elexibility can be
easi-Ly given in man-lfacture according to used conditions,
thereby eliminating the disadvantages in two directly
contacted metals oE the prior art. According to the
05 invention, therefore, there is no risk of damage of
contacts clue to separation of metals because the
pliability of the plastic material absorbs the strains
due to difference in coe.Efi.cient of -thermal expansion
of the two metals and due to difference in elongation
caused by bending in forming and -using the contacts.
Moreover, the interposed plastic l.ayer 3 prevents -the
change in composition of the metal layers due to dif:Eusion
with the lapse of time whi.ch would occur in -two directly
contacted metals of the prior art, thereby preventing
the deterioration of the contacts. F-urthermore, if the
plastic layer 3 having insulating property is ~sed, the
two metal layers 1 and 2 are electrically insulated
from each other to prevent a local cell or battery
caused by the difference in electric potential between
two metals, thereby preventing the disintegration due
to electrochemical corrosion. ~n this manner, all the
disadvantages of the prior art including two direct].y
contacted metals are comple-tely eliminated.
The following significant advantages for
constituting connectors can be accomplished by the
contacts comprising the interposed plastic layers 3
according to the invention. For example, as shown in
Fig. 6a, firs-t metal layers 1 of a contact forming
~2~
mater:ia1 ~1 in a plate shape accordi1lg to the invention
is etched or t-reated by any other method to Eorm a
half-~inishecl product inclwding groups of contacts 5 of
desirecl size and number with desired intervals.
05 This obtained product is folded substantially along its
center line and formed so as to ha-ve contacting portions
extending outwardly as shown in Fig. 6b. Thus formed
product is fixed to an i,nsulator bocly 6 as shown in
Fig. 6c. On the o-ther hand, two contaet forming
materi,als 4 and 4' as s~hown in Fig. 7a are formed so as
to have contacting portions of gro-ups of contacts 7
ex-tending outwardly as shown in Fig. 7b. These materials
4 and ~l1 are then fixed to an insulator bocly 8 as shown
in Fig. 8. In this manner, a multi contact connector
is obtained which comprises groups of contacts 5 and 7
as male ancl female contacts, respectively.
Therefore, the invention provides a con-tact
group eomprising a great number of contae-ts not
deformable) fine and inexpensive and arranged at high
density and with high accuracy in an inexpensive manner,
which could not be accomplished by con-tacts of the
prior art made by pressing expensive beryllium-copper
alloy or the like. By fixing -the contact groups onto
insulating bloeks, connectors having less number oE
parts can 'be simply produced.
Aecording to the invention, thereEore, small-
sized multi contact connectors can be produced with low
cost, inasmueh as it is not req~1ired to take aecount of
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cleformations o~ contacts and manu:Eacturing accuracy or
tolerance o:~ distance between ape-rtures :Eor mounting
which are required in the pr:ior art including a grea-t
number of contacts formed by pressing and inserted and
05 ~ixed into corresponding apertures -formed in insulating
blocks.
Although the invention has been shown with
the first and seconcl metal layers and the plastic
layer, this is only by way of example, and any materials,
shapes, th:icknesses and laminated numbers could be
provided as necessary so long as the contact forming
material comprises a concluctive ma-terial, a spring
material and a plas-tic material. For example, it may
comprise a first high conductive metal layer l, two
metal layers 2a and 2b having a high springiness, and
two plastic layers 3a and 3b interposed -therebetween as
shown in Fig. 9a. As shown in Fig. 9b, moreover, a
metal layer l having the conductivity may be formed by
two metal layers la and lb, and between these metal
layers is interposed a spring metal layer 2. Between
these metal layers may be inserted plastic layers 3a
and 3b having an insulating property or a conductivity
to form laminated contact. In this manner, various
changes can be made without departing -from the scope of
the invention.
~ oreover, without providing the independent
plastic layer, for example, a copper foil and a stainless
steel foil may be join-ted by a heat-welding plastic
adhesive which serves as the plastic layer 3. As an
alternative, a s~ainless steel foil is coated on its
one s~lrface with a plastic material which is in turn
provided on its surface with a metal such as copper,
05 silver or the like by vapor deposition, ion plating or
the like. In order to improve environment-resistance,
wear-resistance, stability of elec-tric connection,
weldability, solderability or the like, moreover, the
first and/or second metal layer or its required partial
and may be provided with a layer (not shown) by metal
plating, chemical treatment such as oxidizing or coating
with an oil, a paint or a coating agent.
While the invention has been particularly
shown and described with reference to preferred embodi-
ments thereof, it will be understood by those skilledin the art that the foregoing and other changes in ~orm
and details can be made therein wi-thout departing ~rom
the spirit and scope of the invention.
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