Abstract: A printed wiring board comprises a substrate, a printed wiring circuit formed on the substrate, and insulating layer formed on the printed wiring circuit, an electromagnetic wave shielding layer provided on the insulating layer, and an overcoat layer provided on the electromagnetic shielding layer. The electromagnetic shielding layer has a first color, and the overcoat layer has a second color different from the first color. The color of the overcoat layer may be any color which is easily visually distinguishable from the color of the electromagnetic wave shielding layer so that visual inspection of the working condition of the overcoat layer is facilitated.

Abstract: A method of manufacturing a printed wiring board. A printed wiring board having a substrate and a circuit pattern formed thereon is provided. At least one through-hole is formed in the substrate. A plurality of fine wires are inserted into the through-hole, and a molten solder is filled into the through-hole by a capillary action due to small gaps formed between the fine wires. A multilayer printed wiring board may be provided comprising a plurality of wiring board layers each having a substrate and a respective circuit pattern formed thereon. The molten solder filled in the through-hole electrically connects at lest two of the respective circuit patterns. The plurality of fine wires may be disposed in a conductive hollow tubular body which is inserted along with the fine wires into the through-hole. Also, the plurality of fine wires may be arranged as a mesh sheet that is formed into a tubular body and inserted into the through-hole.

Abstract: The method for manufacturing the printed wiring board having a shield layer of the present invention is characterized in that, in a method for manufacturing a printed wiring board wherein a printed wiring circuit is provided on one or both sides of an insulating board and a shield layer is provided on the printed wiring circuit through an insulating layer, a shield layer and an earth circuit are formed on the insulating layer while injecting under pressure a coating for shield from a filling nozzle through a mask.

Abstract: According to the present invention, inequality in the film thickness of the solder resist and the occurrence of the blur can be eliminated, and it is possible to perform a screen printing for the solder resist with a minute pattern which leads to the formation of a minute solder land.A solder resist 60 is screen printed while leaving an etching resist 3 in the step for forming a printed wiring circuit 5 on the front of an insulating board 4. Afterward, the etching resist and the overlaid solder resist 60a are simultaneously removed, thereby forming a flat surface over the printed wiring circuit 5.

Abstract: A mold used in producing printed wiring board is disclosed. The mold comprises upper dies and lower dies for sandwiching a printed wiring board therebetween, thereby performing drilling, punching or the like, one of said upper dies and lower dies having a press surface which is provided with concave or convex portions for absorbing steps caused by forming a printed wiring circuit on the printed wiring board.

Abstract: A printed wiring board having a shielding layer for use in an integrated circuit is disclosed. The printed wiring board comprises an insulating sheet having a connecting through hole portion, a printed wiring circuit provided on one or both surfaces of the insulating sheet, an insulating layer having a thickness of 20.about.50 .mu.m which is provided on the printed wiring circuit, and an electromagnetic shielding layer provided on the insulating layer.

Abstract: A printed wiring board includes an insulating substrate having a wiring circuit formed on at least one side thereof. An insulating layer is formed on the wiring circuit and has a plurality of individual curved openings extending therethrough to expose corresponding connection lands of a ground circuit of the wiring circuit. An electromagnetic wave shielding layer is formed on the insulating layer over a portion of the wiring circuit and electrically and mechanically connects with the ground circuit through the connection lands. The curved openings are circular, elliptical or similar shape and dimensioned to prevent formation of bubbles when forming the electromagnetic wave shielding layer thereby enhancing the electrical and mechanical connection between the electromagnetic wave shielding layer and the planar connection land. The curved openings also prevent thinning of the wave shielding layer at the connection lands so as to prevent an increase in connection resistance.

Abstract: A method of manufacturing a printed wiring board comprises providing a substrate and forming a printed circuit having a ground circuit on the substrate. An insulating layer is formed on the substrate over the printed circuit and consists of two successively formed insulating layers having concentric circular apertures defining an opening above the ground circuit. The opening has a circular, stepped shape effective to facilitate the subsequent formation of an electromagnetic wave shielding layer. An electromagnetic wave shielding layer is formed by silk screening a conductive paste on the substrate over the insulating layer and through the opening and over the ground circuit.

Abstract: A method for masking through-holes during the manufacture of a printed circuit board comprises providing a substrate having a plurality of through-holes. A removable masking seal comprised of a soluble material, a light-setting material or a thermo-setting material is formed on the surface of the substrate to cover at least one of the through-holes. At least one of the through-holes that is not covered with the masking seal is filled with a filler material by a conventional silk screen process. The masking seal is then removed, either by dissolving the masking seal in the case of the soluble material, or in the case of the light-setting or thermo-setting material, the masking seal is set by applying light or heat to reduce adhesion between the masking seal and the substrate, and then the set masking seal is peeled off to expose the through-hole.

Abstract: A method of manufacturing printed wiring board is disclosed. The method comprising steps of providing a double-sided copper clad laminate; embedding a conductive ink into a through hole provided in the copper clad laminate; subjecting the opposing surfaces of the double-sided copper clad laminate to copper electroplating to form a copper plated layer after curing the conductive ink under the given conditions; providing a circuit for displacing component mounting lands onto the copper plated layer directly over the cured conductive ink with the use of a dry film or ink for forming other circuit; and forming a printed wiring circuit with the material removing treatment.

Abstract: The invention has been achieved to solve the problem mentioned above. The object of the invention is to provide a novel method of manufacturing a printed wiring board by allowing manufacturers to provide a slit and perforations on the substrate without causing even the slightest crack to be generated in the course of manufacturing the printed wiring board.In the course of manufacturing printed wiring boards splittable across a slit and perforations,the method embodied by the invention executes those sequential steps including the following; provision of thickness adjusting film for specific regions adjacent to the slit and perforations; adjustment of the thickness of a main substrate and a splittable substrate which is splittable by means of the slit and the perforations; and formation of the slit and the perforations by applying a pressing and punching process.

Abstract: A method of packing filler into through-holes in a printed circuit board is disclosed. The method comprises steps of packing the filler through a mask into the through-holes and at the same time smoothing protrusions of the filler at the upper and lower openings of the through-holes by means of squeegees. In this method, the mask may be a silk screen provided with open-worked packing holes for packing the filler in the positions corresponding to those in which the through-holes of said printed circuit board are packed. In the above method, the filler may be packed by delivering pressurized filler from a packing nozzle, which comprises 1) a packing means connected both to a manipulation means for actuating a delivery valve for delivering the filler from said nozzle tip and to a supply means for supplying the filler and 2) a nozzle tip attached to the delivery end of said packing nozzle. In the above-described method, said filler may be a solvent-less filler.

Abstract: A printed wiring board has a substrate having an outer peripheral edge. A printed circuit is formed on at least one side of the substrate. A shock-absorbing band formed of copper foil is disposed along at least a portion of the outer peripheral edge of at least one side of the substrate and is effective to absorb at least some of the impact applied to the printed wiring board during cutting thereof.

Abstract: A printed wiring board includes a substrate having an electrically conductive pattern disposed on at least one side of the substrate. An electrically conductive through-hole is formed in the substrate. At least one of a solder resist film and an electromagnetic shielding layer undercoat film are disposed over the conductive pattern but do not cover the electrically conductive through-hole. An ink layer is formed over at least one end of the electrically conductive through-hole. A method of manufacturing the printed wiring board embodied by the invention comprises providing a substrate having an electrically conductive through-hole. A conductive pattern is formed on at least one side of the substrate. At least one of a solder resist film and an electromagnetic shielding layer undercoat film are formed over the conductive pattern but not over the electrically conductive through-hole. An ink layer is formed over at least one end of the electrically conductive through-hole.

Abstract: A printed circuit board having through-holes and a test land for testing the through-holes. The test land is composed of a pair of current measurement lands and a pair of resistance measurement lands in order to test accurately the packing conditions of the conductive paste packed in the through-holes, thereby improving the uniformity and completeness of conductive-paste packing in printed circuit boards.

Abstract: Circuit ends of a cancel loop circuit and a frequency generator circuit are connected with circuit lands in such a manner that the two circuits are not allowed to electrically communicate with each other. The cancel loop circuit and the frequency generator circuit are subjected to an electrical conductivity test to detect any short circuit therebetween. After successful testing, the lands located adjacent each other at one side of the circuits are connected with each other, thereby electrically communicating the cancel loop circuit and the frequency generator circuit to obtain a completed coil circuit.

Abstract: A printed wiring board shielded from electromagnetic wave radiation has a conductive circuit pattern formed on an insulating substrate, a first insulating layer disposed over the circuit pattern, a jumper wire formed over the first insulating layer and between connecting terminals of the conductive pattern, a second insulating layer covering the jumper wire and the first insulating layer, and an electromagnetic wave shielding layer disposed over the conductive pattern. The jumper wire is formed by printing using a conductive paste containing a conductive material such as silver, carbon or copper. The shield layer is formed by printing using a conductive metal resin paste such as copper. An overcoat layer is applied over the shield layer to protect the shield layer.

Abstract: Method to form a photosensitive ink film having an even thickness over the entire surface of a broad plate material capable of obtaining a multiplicity of printed wiring boards. An emulsion pattern 4 is provided on a screen 3 on which a squeegee travels. The pattern 4 is formed correspondingly to a cutting spaces of a plate material for the purpose of obtaining a multiplicity of printed wiring boards. When a photosensitive ink is forced onto the broad plate material through a screen 3 for a screen printing, the photosensitive ink is dispersed by the pattern 4, thereby forming a film of even thickness over the entire surface of the plate material not corresponding to the emulsion pattern.

Abstract: A printed wiring board for forming an electric connection to an external device. The printed wiring board comprises a base material, and at least one connecting terminal formed on the base material for forming an electrical connection to an external device. A solder resist layer is formed on at least a portion of the base material surface excluding a connecting terminal forming region. A conductive protective layer is formed over the connecting terminal forming region and covers the connecting terminal. The end portion of the solder resist layer is separated from the end portion of the conductive protecting layer. An overcoat layer is formed on the separating portion for bridging the end portion of the solder resist layer and the end portion of the conductive protecting layer.

Abstract: In a method of manufacturing printed circuit boards by coating a flux preventive film for preventing a flux from rising on a component surface of an insulation board, the method of manufacturing printed circuit boards according to the present invention is characterized in that said method comprises the steps of printing white blank marks, white blank symbols and white blank letters corresponding to symbol marks, other symbols and letters on the component side surface of said insulation board before coating said flux preventive film, and then coating said flux preventive film of a transparent or translucent material on the printed surface.