Electronic components are shielded from electromagnetic interference (EMI) by one or more conformal layers filled with selected filler particulars for attenuate specific EMI frequencies or a general range of frequencies. Shielding is accomplished through the use of a single general purpose shielding layer, or through a series of shielding layers for protecting more specific EMI frequencies. In a multilayer embodiment, a semiconductor device (50) is mounted on a printed circuit board substrate (16) as a portion of an electronic component assembly (10). A conformal insulating coating (24) is applied over the device to provide electrical insulation of signal paths (e.g. leads 54 and conductive traces 18) from subsequently deposited conductive shielding layers. One or more shielding layers (60, 62, and 64) are deposited, and are in electrical contact with a ground ring (56). In a preferred embodiment, the ground connections for the shield layers are separate from those used for power distribution within the devices.

Shielded electronic component assembly and method for making the same

Printed circuit board

Electrically conductive adhesive compositions and methods for the preparation and use thereof, in which a solder powder, a chemically protected cross-linking agent with fluxing properties and a reactive monomer or polymer are the principal components. Depending upon the intended end use, the compositions comprise three or more of the following: a relatively high melting metal powder; solder powder; the active cross-linking agent which also serves as a fluxing agent; a resin; and a reactive monomer or polymer. The compositions are useful as improved conductive adhesives, such as for attaching electrical components to electrical circuits; the compositions comprising metal powder are ideally suited for creating the conductive paths on printed circuits. The compositions for forming conductive paths may first be applied to a substrate in the desired pattern of an electrical circuit, and then heated to cure it. During heating, the action of the cross-linking agent and optional reactive monomer or polymer within the mixture fluxes the metals, enabling sintering to occur between the metal powder and the solder powder.

Electrically conductive compositions and methods for the preparation and use thereof

[purpose] The provision of an electroconductive metal paste of low temperature sintering type for use in printing a high density circuit, which exhibits good adhesion and a smooth surface when applied on a substrate and burned, and thus can be used for forming a fine circuit exhibiting a low resistance. [constitution] An electroconductive metal paste which comprises a resin composition comprising a thermosetting resin component, an organic acid anhydride or a derivative thereof or an organic acid, and one or more organic solvents and, dispersed homogeneously therein, as an electroconductive medium, ultra-fine metal particles having an average particle diameter of 100 nm or less and being surface-coated with one or more compounds having a group capable of forming a coordinate-type bonding with a metal element contained in said ultra-fine metal particle through a lone electron pair of N, O or S, optionally in combination with a metal filler having an average particle diameter of 0.5 to 20 νm. The electroconductive metal paste can undergo low temperature sintering between ultra-fine metal particles contained therein when the paste is subjected to a low temperature heat treatment.

Electroconductive metal paste and method for production thereof

Methods for fabricating single and multilayer printed boards which employ electronically conductive adhesive compositions are provided. The composition comprises a solder powder, a chemically protected cross-linking agent with fluxing properties and a reactive monomer or polymer as the principal components. The compositions may also comprise three or more of the following: a relatively high melting metal powder; solder powder; the active cross-linking agent which also serves as a fluxing agent; a resin; a reactive monomer or polymer; and a metal additive. Compositions comprising metal powder are ideally suited for creating the conductive paths and vias on printed circuits.

Multilayer printed circuit

A printed circuit board includes a first electric conductive layer formed on an insulating base plate to form signal patterns and a ground pattern. An insulation layer covering the signal patterns and a second electric conductive layer connected to the ground pattern are sequentially formed on the plate. A large area ground land is formed in the vicinity of a ground terminal of a digital IC by the first electric conductive layer to be connected to the ground terminal, which is directly surface-connected to the second electric conductive layer so that a ground impedance of the ground terminal can be reduced. A large area power source land connected to a power source terminal of the digital IC is formed in the vicinity of the power source terminal by the first electric conductive layer, which sandwiches the insulation layer in cooperation with the second electrostatic conductive layer so that an electrostatic capacitance larger than a line-to-line distribution capacitance formed by the signal patterns can be formed between the power source land and the second electric conductive layer.

Printed circuit board capable of preventing electromagnetic interference

The invention relates to an electroconductive coating composition with excellent conductivity, adhesion to copper foil and solder dip resistance which is suitable for the formation of a jumper circuit and an electromagnetic shield layer, a printed circuit board fabricated with the above composition, and a durable electromagnetic-shielded flexible printed circuit assembly, wherein said coating composition comprises, by weight, 100 parts of copper metal powder coated with 0.05-0.2 parts of titanate or/and zirconate, 5-30 parts of resole phenolic resin, 0.5-4 parts of a chelating agent, 0.1-5 parts of an adhesion improving agent and 0.5-7 parts of a conductivity improving agent. This composition is less expensive than the silver paste, superior to the latter in the conductivity and adhesion to copper foil of the coating film and in solder dip resistance, thus being suited for the construction of a jumper circuit and an electromagnetic shield layer. It lends itself well to the mounting of IC, MSI, LSI, etc. by dipping in a molten solder bath.

Electroconductive coating composition, a printed circuit board fabricated by using it and a flexible printed circuit assembly with electromagnetic shield

A conductive copper paste composition is adapted to yield a highly conductive film receptive to solders without pretreatment. This conductive paste comprises a copper metal powder, a resin component including a thermosetting resin, and an assortment of additives. In use, the paste is applied to an insulation substrate to a predetermined circuit pattern and cured in situ. Soldering can then be performed directly on the cured circuit. This contributes not only to the conductivity of the circuit but dispenses with the activation treatment and electroless plating or electroplating that have heretofore been essential prior to soldering. The invention, therefore, results in a substantial curtailment of production process and a proportional economic advantage. In addition, this conductive paste can be used in such applications as electrode and through-hole connections, formation of electromagnetic and electrostatic shield layers, and so on in the manufacture and assembly of electronic components and circuits.

Conductive copper paste composition

The radiation noise suppression effect is enhanced by providing an insulation layer which is formed so that the circuit pattern is covered excepting at least a part of power source pattern or ground pattern on the substrate on which circuit pattern is formed, and a conductive layer which is formed so as to be connected to the uninsulated part of the power source pattern or the ground pattern on the insulation layer, by modifying pattern shape of the conductive layer and the insulation layer or by increasing or reducing the number of these layers.

Printed circuit board having enhanced EMI suppression

PURPOSE:A composition which is applied to a circuit board by screen printing and cured to show electrical conductivity in a good state for a long period, obtained by blending a mixture of a resol type phenolic resin and a butylphenolic resin with copper powder, an unsaturated fatty acid or its alkali metal salt. CONSTITUTION:100pts.wt. copper powder is blended with 15-45pts.wt. mixture of a resol type phenolic resin and p-tert-butylphenolic resin (in a weight ratio of 65:35-97:3), and 0.5-7pts.wt. unsaturated fatty acid or its alkali metal salt. The butylphenolic resin used has <=50 polymerization degree. Oleic acid or linoleic acid is preferable as the unsaturated fatty acid.

Shinichi Wakita

Papers

Printed circuit board capable of preventing electromagnetic interference

Electroconductive coating composition, a printed circuit board fabricated by using it and a flexible printed circuit assembly with electromagnetic shield

Conductive copper paste composition

Printed circuit board having enhanced EMI suppression

Electrically-conductive copper paste composition