Abstract:
A substantially warp-free laminate polymeric film structure is obtained by a fabrication process in which the individual layers of polymeric film that are to be laminated together to form a card or similar structure are selected such that the mechanical properties of one layer or pair of layers are offset by those of another layer or layer pair wherein each polymeric film layer is bonded to its adjacent polymeric film layers by adhesive layers wherein the adhesive layers have a tack point temperature that is within 10.degree. C. of the glass transition temperature of said polymeric film layers. The properties of the layers which may be subject to this consideration include, for example, the layer thickness, tensile strength, elongation factor, shrinkage rate, and machine processing direction. In an illustrative three-layer substrate embodiment of the present invention, the tensile strength, elongation factor, and shrinkage rate of the outer film layers of the substrate are the same, with the outer layers having a higher tensile strength value than the inner layer tensile strength. The orientation of the film's processing and machine direction and the orientation of the coil set of the film are also considered in arriving at a matched layer set.
Abstract:
A substrate for a laminate which comprises a nonwoven fabric which is composed mainly of a liquid crystal polyester fiber, and which is subjected to (1) an entangling treatment, (2) a heating treatment to impart adhesivity to a thermosetting resin, and (3) a surface-modifying treatment, and a laminate containing at least one prepreg prepared by impregnating the substrate with a thermosetting resin and drying are disclosed. The substrate of the present invention has low dielectric constant, is light, exhibits low hygroscopicity, and has good properties to be impregnated with the thermosetting resin and good adhesiveness to the thermosetting resin.
Abstract:
Conductor-filled thermosetting resins having a free radical based cure chemistry are prepared for use as solder paste replacements for electrical conducting attachments of surface mount electronics components to printed circuit boards and as a die attach adhesive. The thermosetting resins exhibit rheological properties that allow them to be substituted for state-of-the-art solder paste and die attach adhesives. The conductor filled resins can be thermally cured in in-line processing operations to provide a low stress, substrate adherent, electrically conductive resin matrix.
Abstract:
A method for making a multilayered printed circuit board including the steps of arranging two plates in spaced relation, arranging a perimetral seal between the two plates with an upper opening in the seal to form an upwardly open chamber, placing a plurality of printed circuit boards between the plates in spaced relation to one another, placing the chamber under vacuum, injecting a settable matrix material into the chamber, compressing the end plates towards one another to achieve the desired outer dimensions of the board, and curing the settable matrix material.
Abstract:
A warp-free laminate is produced by winding a first set of strands or filaments about a flat mandrel with a second set of strands being wound transverse to the first set. The two sets may be perpendicular to each other. The filaments are maintained under a controlled tension while being impregnated with a resin and during subsequent cure of the resin. In order to permit the formation of a warp-free product, the winding pattern is such that it forms a mirror image about a neutral axis or plane of symmetry. The winding pattern may be chosen to provide interstices in a predetermined pattern permitting punching out or high speed drilling of hole openings for subsequent printed circuit applications.
Abstract:
A printed circuit board material composed of a reinforcing base material and a cured or uncured resin is disclosed, in which the base material is a fabric woven from hybrid yarns each of which is prepared from (I-1) at least one multifilament yarn made of glass fiber having a dielectric constant at 1 MHz of not higher than 5.5 or (I-2) at least one multifilament yarn made of heat resistant engineering plastic fiber having a dielectric constant at 1 MHz of not higher than 5.5 and (II) at least one yarn made of fluoroplastic long fiber and the thermosetting resin is a thermosetting resin whose dielectric constant after curing is not higher than 3.7. The material is excellent in dielectric properties and characteristics required for use in printed circuit board, such as heat resistance in soldering, flexural strength and peel strength of copper foil. The material shows substantial constancy of dielectric constant even with change of resin content and is therefore particularly suitable for use in a multilayer printed circuit board.
Abstract:
Disclosed are improved laminates useful in the manufacture of multi-layer printed wiring boards (MLPWB) and laminates. Such improved composites contain at least one layer which is formed from a liquid crystal polymer selected from the group consisting of poly(para-phenylene benzobisthiazole), poly(paraphenylene benzobisoxazole), poly(2,5-benzothiazole), poly(2,5-benzoxazole), and mixtures thereof. The presently preferred liquid crystal polymer comprises poly(para-phenylene benzobisthiazole). The negative coefficient of thermal expansion and high modulus of elasticity of the liquid crystal polymers enable a laminate and MLPWB to be manufactured therefrom having a tailored coefficient of thermal expansion, broadly ranging from about 0 to 15 ppm/.degree. C. MLPWBs constructed of polymeric core layers also are possible utilizing the preferred liquid crystal polymers of the present invention.
Abstract:
A composite polyester sheet which comprises a polyester film, a layer of a vinyl chloride plastisol composition (A) containing an adhesion-imparting agent, formed on the film and a layer of a vinyl chloride plastisol composition (B) containing no adhesion-imparting agent, formed on the layer of the composition (A).
Abstract:
A laminate is made of textile sheet structures of synthetic fibers or glass fibers with a covering of polypropylene. The polypropylene is crosslinked by addition of crosslinking agents. The laminate has good electrical insulating properties, perfect solder bath stability, and good mechanical machinability. This laminate is provided, in heated presses, with metal layers or can be provided, in heated presses, with metal layers or can be provided with such metals layers by the application of metallic foils or by electrolytical methods, and serves for the manufacture of printed circuits and ribbon cables. An advantageous production of the textile sheet structures encased with crosslinked polypropylene can be performed on roll stands by thermoplastic encasing and smoothing in a continuous process.
Abstract:
At both ends of glass cloth comprising warp yarns consisting of a number of glass monofilaments and weft yarns consisting of a number of glass monofilaments, the weft yarns being cut at the ends of the glass cloth, glass monofilament-fixing portions are formed by fusing the ends of the weft yarns, by substituting a synthetic resin yarn for the warp yarn at the end of the glass cloth and melting the synthetic resin yarn or by attaching an adhesive tape to the ends of the glass cloth. The glass cloth having the glass monofilament-fixing portions at both ends thereof is advantageous in that no broken pieces of glass monofilament were formed when preparing prepreg or laminate using the glass cloth, and the laminate has excellent accuracy of thickness.