Electrical connectors – Including elastomeric or nonmetallic conductive portion – Adapted to be sandwiched between preformed panel circuit...
Reexamination Certificate
1998-06-08
2001-02-06
Patel, T. C. (Department: 2839)
Electrical connectors
Including elastomeric or nonmetallic conductive portion
Adapted to be sandwiched between preformed panel circuit...
C439S066000
Reexamination Certificate
active
06183272
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention generally relates to elastomeric contacts, and in particular to contacting arrangements and mechanical assemblies for contacting a plurality of electronic modules.
In complex electronic systems comprising a plurality of electronic modules and PC-boards (and therefore may have a high count of electrical contacts), the mechanical and electronic assembling of those modules and PC-boards has become more and more important. This is, on one hand, due to more and more complex and integrated structures and constraints in assembling space, and on the other hand, due to heat and cooling problems involved within the electronic system. Furthermore, a modular assembling is desirable.
Mechanical and electronic contacts provided by elastomeric materials (elastomeric contacts) are often used for achieving detachable connections. EP-A-0 238 410 and EP-A-0 558 855 disclose arrangements which use such elastomeric contacts for providing a resilient contact.
FIG. 1
shows the principal structure of an elastomeric contact
10
as known in the art. Elastomeric contacts
10
are electrically conductive contact media fibers, and an elastic carrier
30
such as silicone rubber, whereby the conductive elements
20
are normally embedded into the elastic carrier
30
.
By applying pressure on adjacent sides of the elastomeric contact
10
, e.g. by pressing the elastomeric contact
10
between a first PC-board
40
and a second PC-board
50
, the carrier material
30
deforms elastically and the conductive elements
20
get in touch with corresponding contact areas of the first and second PC-board
40
and
50
, and thus establish an electrical (and mechanical) contact between the first and second PC-board
40
and
50
. The conductive elements
20
within the elastic carrier
30
can be arranged e.g. in rows (as indicated in
FIG. 1
) or in any other desired order.
A variety of elastomeric contacts
10
based on solid insulating silicone rubber is provided as GB-type inter-connectors by Shin-Etsu Polymer Company Ltd, Japan. For connecting small-pitch PC-boards, insulating sponge rubber may be applied to the solid rubber for support, as provided as a GN-type inter-connectors by Shin-Etsu Polymer Company Ltd, Japan.
GB-A-2 269 061 and U.S. Pat. No. 4,201,435 disclose elastomeric contacts, each comprising a unit with conductive elements embedded into a resilient material. In WO-A-96 22621, the conductive elements are partly embedded into a strengthening material. This unit is further embedded into a flexible and resilient material. Other elastomeric contacts are disclosed in U.S. Pat. No. 5,500,280 and GB-A-2 054 284.
It has been found that only a limited amount of pressure can be applied onto those elastomeric contacts
10
as known in the art, when a contact as shown in
FIG. 1
is to be established. This is due to the elastic properties of the elastic carrier
30
, so that the elastomeric contact
10
tends to “flow” when pressure is applied, meaning that the elastomeric contact
10
changes its internal and external shape and lateral dimensions under the influence of pressure. Particularly when the elastomeric contact
10
comprises a plurality of rows of conductive elements
20
, the position of the contact areas of the elastomeric contact
10
provided by the individual conductive elements
20
might vary. This can lead to a mismatch in position of the contact areas of the elastomeric contact
10
with respect to the respective contact areas to be contacted, e.g. of the first and second PC-board
40
and
50
, and thus to contact defects such as higher resistance or that no contact is established. Furthermore, the elastomeric contact
10
generally does not allow a thermal contact between the modules to be contacted, due to the low thermal conductivity of the elastomeric contact
10
. GB-A-2 276 502 discloses an anisotropic conductive elastic connector comprising vertical conductive elements which are embedded into 3 horizontal layers of insulative elastic sheets, whereby a layer formed of a compressible foam synthetic resin material is provided between two adjacent layers formed of a resilient non-foam synthetic resin material. GB-A-2 276 502 overcomes the above mentioned disadvantages and solves the problem of “flowing”. However, disadvantageous in the arrangement of GB-A-2 276 502 is that this arrangement is difficult to manufacture, e.g., since the conductive elements have to be kept aligned during the manufacturing process until all layers have been sequentially applied.
It is therefore an object of the present invention to provide a compressible elastomeric contact which is easier to manufacture.
As pointed out above, elastomeric contacts are often applied in contacting arrangements for providing an electrical contact between electronic modules. GB-A-2 276 502 further discloses a contacting arrangement for providing an electrical contact between a wiring board and an IC package. The arrangement comprises the above described elastomeric contact and a connector frame for positioning the elastomeric contact.
It is a further object of the invention to provide another contacting arrangement for providing an electrical contact between electronic modules.
SUMMARY OF THE INVENTION
An elastomeric contact according to a first aspect of the invention, for providing an electrical contact, comprises a stabilizing unit with one or more conductive elements embedded into a strengthening material. The stabilizing unit again is embedded into a compressible material.
An elastomeric contact according to a second aspect of the invention comprises a plurality of compressible layers of a compressible material; and a plurality of contact layers of a strengthening material, each with at least one embedded conductive element; whereby each one of the plurality of contact a layers is arranged between adjacent ones of the compressible layers.
In the elastomeric contact according to the invention, the compressible material will be compressed under the influence of pressure. Due to the arrangement of compressible materials and strengthening materials within the elastomeric contact, a “flowing” of the strengthening material and thus of the conductive elements under the influence of pressure is reduced to a minimum degree. In case that an arrangement of a plurality of individual layers is selected, wherein adjacent layers of strengthening material are separated by one layer of compressible material, the “flowing” of one individual layer or of the strengthening material will not influence a next layer of strengthening material, or only to a minimum degree.
The elastomeric contact according to the invention thus allows an increased amount of pressure to be applied onto the elastomeric contacts. A mismatch in position of contact areas of the elastomeric contact with respect to respective contact areas to be contacted will be avoided.
A contacting arrangement according to a third aspect of the invention, for providing an electrical contact between a first and a second module, comprises a compressible elastomeric contact according the first or second aspect, and a positioning frame for positioning the elastomeric contact. The positioning frame has substantially the same inner dimensions as the outer dimensions of the elastomeric contact, and the height of the elastomeric contact is at least slightly greater than the height of the positioning frame.
The contacting arrangement allows an easy and precise positioning of the elastomeric contact. Furthermore, an improved thermal contact between modules to be contacted can be established when the contacting arrangement is pressed between the modules, and particularly when the positioning frame is provided as a thermally high conductive material.
A mechanical assembly according to a forth aspect of the invention, for contacting a plurality of electronic modules, comprises the contacting arrangement according to the third aspect arranged between adjacent ones of the plurality of electronic modules.
The mechanical assembly allows an easy handl
Müller Marcus
Neuweiler Rolf
Hewlett--Packard Company
Patel T. C.
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