Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Compositions to be polymerized by wave energy wherein said...
Reexamination Certificate
1999-07-26
2001-04-17
Seidleck, James J. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Compositions to be polymerized by wave energy wherein said...
C522S071000, C522S150000, C522S173000, C522S182000, C524S901000, C524S780000, C524S781000, C524S785000, C524S786000, C524S776000, C524S779000, C427S487000, C427S500000, C427S400000
Reexamination Certificate
active
06218446
ABSTRACT:
BACKGROUND OF THE INVENTION
Metal-filled electrically conductive synthetic resinous materials are well known in the art. For example, Frentzel et al. U.S. Pat. No. 5,395,876 provides a surface mount conductive acrylate adhesive composition that includes about 72 to about 92 parts by weight of finely divided silver particles, typically in the form of flakes having an average particle size of about 0.1 to about 10 microns and a surface area of approximately 0.8 to 1.4 square meters per gram. The adhesives may also include 0.05 to 20 parts by weight of an optional conductive filler, such as powders and flakes of other metals, graphite, and carbon black.
Formulations that cure under ultraviolet irradiation, to produce electrically conductive adhesives, have been commercially available for many years. Electrical conductivity is imparted by adding to the adhesive formulation balls or flakes that are made of, or are coated with, a metal, usually silver. Consistent with the disclosure of Frentzel et al., a high loading of the filler is necessary in such products to provide the mutual contact of the filler elements that is required for conductivity. Moreover, reflectance from the metal surfaces of the filler precludes substantive penetration of the actinic radiation into the polymerizable mass, typically limiting cure to a relatively shallow layer at the exposed surface; efforts to cure such resins to greater depths have conventionally relied upon the incorporation of thermal catalysts or other means for providing a secondary cure mechanism.
It is known that increased depths of cure can be realized by incorporating relatively transparent semiconducting additives into resinous formulations. The resultant cured deposits exhibit relatively poor conductivity, however, typically having a resistance well in excess of 1,000 ohms, whereas much higher values of conductivity (resistances in the range 0.001 to less than 1,000 ohms) are desired.
U.S. Pat. No. 4,113,981, to Fujita et al., provides an electrically conductive adhesive that comprises electrically conductive particles mixed in a non-conductive base at such a mixing ratio that the conductive particles are not in contact with on another. When the adhesive is disposed between facing electrodes it provides electrical conductivity between the electrodes but maintains electrical insulation in the lateral direction.
U.S. Pat. No. 4, 554,033, to Dery et al., provides interconnecting means comprised of a conductive ink element printed upon a first substrate, the conductive ink being comprised of an insulating polymer medium having first and second groups of conductive particles therein, and an insulating layer of flowable adhesive in covering relationship to the conductors. The particles of first group are finely divided and are suspended in the medium to form a continuous conductive path along the length of the conductor. The second group of particles are agglomerates of large particles, which are randomly scattered throughout the conductive path and project above the surface of the medium. Interconnection is effected by positioning the first substrate conductors in an overlapping conducting relationship to the conductors on the second substrate, such that the flowable adhesive is disposed between the two substrates, and applying pressure to the positioned conductors and surrounding areas. The adhesive flows and exposes the protruding agglomerates, thus bringing the agglomerates into contact and electrical interconnection with the conductors while also causing the adhesive to bond the substrates to one another.
U.S. Pat. No. 4,595,604, to Martin et al., provides conductive compositions that are solderable and flexible and that can be bonded directly to substrates. The compositions are made up of a combination of silver, exclusively in the form of flake, and a resin system comprised of vinyl chloride/vinyl acetate copolymer, epoxy resin, and epoxy hardener.
In accordance with Tsukagoshi et al. U.S. Pat. No. 4,740,657, connection of conductors can be accomplished by using an adhesive composition or film capable of exhibiting anisotropic-electroconductivity, the electroconductive particles comprising polymeric core materials coated with thin metal layers; the composition includes an electrically insulating adhesive component.
U.S. Pat. No. 4,959,178, to Frentzel et al., provides an actinic radiation curable polymer thick film composition comprising, by weight: (a) about 10 to about 20 parts of an unsaturated monomer capable of being polymerized by actinic radiation; (b) about 2.5 to about 8 parts of at least one thermoplastic polymer having a glass transition value of above about 100° F. and not being capable of substantial cross-linking with monomer (a), polymer (b) being dissolved in monomer (a); (c) about 68 to about 85 parts of conductive metal particles; and (d) about 0.1 to about 5 parts of at least one actinic radiation polymerization initiator.
In the electrode arrangement described in Mose U.S. Pat. No. 5,235,741, first and second substrates are bonded together using a UV light curable adhesive. The adhesive carries first and second dispersed particles; the first particles are conductive, and preferably resilient, and function to form current paths between electrodes on the second substrates, while the second particles function to prevent excess deformation of the first particles.
SUMMARY OF THE INVENTION
Broad objects of the present invention are to provide a novel radiation-curable formulation for producing a solid deposit, a novel method for producing such a deposit on a substrate, and the novel article so produced, whereby and wherein an increased depth and completeness of curing can be achieved, as compared to similar conventional formulations, methods and articles.
More specific objects of the invention are to provide such a formulation, method, and article wherein and whereby electrical conductivity is imparted to the cured deposit, and wherein and whereby the cured deposit is of high quality and of substantially wrinkle-free surface character.
It has now been found that certain of the foregoing and related objects of the invention are attained by the provision of a radiation-curable formulation for producing an electrically conductive solid deposit, which formulation comprises a radiation-curable composition containing at least one polymerizable ingredient and a photoinitiator for effecting polymerization of the ingredient; and an electrically conductive filler dispersed in the composition in an amount sufficient to impart substantial electrical conductivity to a cured deposit of the formulation. The electrically conductive filler employed is comprised of a primary component constituted of electrically conductive elements of elongate form having surfaces that reflect substantially at least one wavelength of actinic radiation to which the photoinitiator is responsive, and a secondary component constituted of elements having at least marginal electrical conductivity (i.e., made of a semiconducting material) and being substantially transparent to the same “at least one” wavelength of radiation; in most instances, the primary component: secondary component volumetric ratio will not exceed about 25:1. Typically, the polymerizable composition will be one that cures by a free radical mechanism, and for maximum effectiveness and efficiency it will usually be most advantageous to employ a photoinitiator (or a combination of photoinitiators) that affords response to wavelengths of actinic radiation in both the ultraviolet and also the visible spectral regions. In preferred embodiments the formulation will additionally include an active oxygen free radical-generating catalyst (i.e., a compound containing the peroxy group, which will normally be subject to thermal activation), e.g., a perester such a t-butyl perbenzoate and t-butyl peroctoate or a hydroperoxide such as cumene hydroperoxide.
The elongate primary filler elements may themselves be metallic; usually however they will comprise a core of a dielectric material such as glass, plast
Arnold John R.
Bachmann Andrew G.
Lam Vu V.
Dorman Ira S.
Dymax Corporation
McClendon Sanza L.
Seidleck James J.
LandOfFree
Radiation curable formulation for producing electrically... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Radiation curable formulation for producing electrically..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Radiation curable formulation for producing electrically... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2491012