Stock material or miscellaneous articles – Composite – Of silicon containing
Reexamination Certificate
2000-10-20
2002-03-19
Moore, Margaret G. (Department: 1712)
Stock material or miscellaneous articles
Composite
Of silicon containing
C428S448000, C428S403000, C428S404000, C428S405000, C428S406000, C428S407000
Reexamination Certificate
active
06358615
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a rubber connector used for electrically connecting a liquid crystal display panel and a circuit board therefor or between two circuit boards. More particularly, the invention relates to an electric connector which is interposed between an array of electrode terminals on a first electronic board unit, e.g., liquid crystal display panel and circuit board, and an array of electrode terminals on a second electronic board unit to establish electric connection therebetween.
It is long since the debut of connectors made of a rubbery elastomer impregnated with fine metal particles or, in particular, with silver particles to impart electric conductivity as a substitute for U-formed metal wire connectors. The rubber connector of the most typical type, referred to as a “zebra” connector hereinafter, is an alternately stratified body consisting of a plurality of layers of an electroconductive rubber and a plurality of layers of an insulating rubber to exhibit a striped appearance resembling the body of a zebra. The zebra connectors are generally preferred to the U-formed metal wire connectors in respect of the stability and reliability of electric connection with little occurrence of connection failure.
One of the problems in the use of silver particles as an electro-conductive powder to impart conductivity to a rubber is that silver particles have a tendency toward agglomerate formation during storage so that difficulties are sometimes encountered in the preparation of an electroconductive rubber composition by compounding with silver particles after prolonged storage. Agglomerated silver particles can hardly be dispersed with full uniformity in the rubber matrix resulting in a decrease in the stability and reliability of the electric connection to be established by using the rubber connector.
While zebra connectors are prepared usually by slicing an alternately stratified block of conductive and insulating rubber layers in a plane perpendicular to the stratified layers, in addition, a trouble may be encountered in the molding and curing of the stratified rubber block, when the conductive rubber composition is prepared with agglomerated silver particles, that separation of layers takes place at the interface between the conductive rubber layers and insulating rubber layers or within a conductive rubber layer so that the zebra connectors of good quality can hardly be produced with stability in mass production.
SUMMARY OF THE INVENTION
The present invention accordingly has an object to provide a zebra connector which can be prepared with high productivity and inexpensiveness in any large quantities without the above described various problems and disadvantages in the prior art rubber connectors utilizing silver particles and which can be used for establishing reliable electric connection between two electronic board units each having an array of electrode terminals with stability in the conductive resistance.
Thus, the present invention provides a rubber connector which is an alternately stratified integral body consisting of a multiplicity of layers of a cured electrically conductive rubber and a multiplicity of layers of a cured electrically insulating rubber, the cured electrically conductive rubber being formed by curing an electrically conductive silicone rubber composition which comprises, as a uniform blend:
(A) 100 parts by weight of an organopolysiloxane represented by the average unit formula
R
n
SiO
(4−n)/2
, (I)
In which R is an unsubstituted or substituted monovalent hydrocarbon group and the subscript n is a positive number in the range from 1.98 to 2.02, at least two of the groups denoted by R in a molecule being aliphatically unsaturated groups;
(B) from 90 to 800 parts by weight of electrically conductive particles, each particle being composed of a core particle of a non-metallic material and a plating layer of a metallic material, such as gold, on the surface of the core particle; and
(C) a curing agent in an amount sufficient to effect curing of the organopolysiloxane.
It is preferable that the non-metallic material of the core particle forming the electroconductive particles (B) is silica and the plating layer of a metal is a bilayered plating layer consisting of an underplating layer of nickel and a top plating layer of gold.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
As is described above, the rubber connector of the present invention is a so-called zebra connector and the most characteristic feature thereof consists in the unique formulation of the electroconductive rubber composition to form the electroconductive rubber layers for stratification with layers of an insulating rubber.
The electroconductive rubber composition, from which the conductive rubber layers of the inventive rubber connector are formed by curing, is a silicone rubber composition and comprises, as the essential ingredients, the components (A), (B) and (C) defined above.
The component (A) in the silicone rubber composition as the first essential ingredient is an organopolysiloxane represented by the average unit formula (I) given above, in which the group denoted by R is a monovalent hydrocarbon group having 1 to 10 or, preferably, 1 to 8 carbon atoms and the subscript n is a positive number in the range from 1.98 to 2.02. It is essential that the groups denoted by R in a molecule of the organopolysiloxane include at least two aliphatically unsaturated groups such as vinyl groups.
Examples of the monovalent hydrocarbon groups denoted by R in the average unit formula (I) include alkyl groups such as methyl, ethyl, propyl, butyl, hexyl and octyl groups, cycloalkyl groups such as cyclohexyl group, alkenyl groups such as vinyl, allyl, isopropenyl, butenyl and hexenyl groups, aryl groups such as phenyl and tolyl groups and aralkyl groups such as benzyl and phenylethyl groups as well as those substituted hydrocarbon groups obtained by replacing a part or all of the hydrogen atoms in the above named groups with substituents such as halogen atoms and cyano groups exemplified by chloromethyl, 3,3,3-trifluoropropyl and 2-cyanoethyl groups, of which methyl, vinyl, phenyl and 3,3,3-trifluoropropyl groups are preferable.
While the organopolysiloxane as the component (A) contains at least two aliphatically unsaturated groups per molecule, the content of such aliphatically unsaturated groups should be in the range from 0.001 to 20% by moles or, preferably, from 0.025 to 5% by moles of the overall groups denoted by R in the average unit formula (I). The subscript n in the average unit formula (I) is a positive number in the range from 1.98 to 2.02. This means that the organopolysiloxane as the component (A) has a substantially straightly linear molecular structure.
The molecules of the organopolysiloxane as the component (A) can be constituted entirely from a single kind of diorganosiloxane units but can be constituted from two kinds or more of different diorganosiloxane units. It is further optional that the component (A) is a combination of two kinds or more of different types of organopolysiloxanes provided that each of them falls within the definition given by the average unit formula (I).
The organopolysiloxane as the component (A) has an average degree of polymerization in the range from 100 to 20000 or, preferably, from 3000 to 10000.
The component (B) as the second essential ingredient of the silicone rubber composition is an electroconductive particulate material consisting of electroconductive particles each composed of a non-metallic core particle and a metallic plating layer thereon. The non-metallic material forming the core particles includes inorganic materials and organic resinous materials. The inorganic powder suitable for the core particles include various kinds of inorganic fillers such as silica, titanium dioxide, alumina, mica, barium sulfate and carbon blacks, of which silica and alumina having, if available, a spherical particle configuration are particularly preferable.
Silica particles, i.e. sil
Feely Michael J
Moore Margaret G.
Shin-Etsu Polymer Co. Ltd.
Wenderoth , Lind & Ponack, L.L.P.
LandOfFree
Rubber connector does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Rubber connector, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Rubber connector will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2830214