Macdermid, Incorporated

John L Cordani

Donald R Ferrier

Gary B Larson

Raymond A Letize

William J Decesare

Edward T Donlon

Donald P Cullen

Richard L Kremer

For attaining adhesion between copper circuitry innerlayers and pre-preg layers in a multilayer printed circuit, a conversion coating of copper oxide is provided on the metallic copper surfaces in a manner which develops an altered topography of the underlying metallic copper surfaces. Thereafter, a controlled dissolution and removal of a substantial amount of the copper oxide is effected, in a manner which does not adversely affect the already-developed topography of the underlying metallic copper, and such that the innerlayer, at the time of assembly with the pre-preg layers, has copper surfaces consisting of the topographically altered metallic copper and a relatively small amount of copper oxide thereon. Excellent bonding strengths are achieved with decreased incidence of pink ring formation as compared to conventional processes utilizing copper oxide for adhesion promotion.

Process for fabricating multilayer printed circuits

For attaining adhesion between copper circuitry innerlayers and pre-preg layers in a multilayer printed circuit, a conversion coating of copper oxide is provided on the metallic copper surfaces in a manner which develops an altered topography of the underlying metallic copper surfaces. Thereafter, a controlled dissolution and removal of a substantial amount of the copper oxide is effected, in a manner which does not adversely affect the already-developed topography of the underlying metallic copper, and such that the innerlayer, at the time of assembly with the pre-preg layers, has copper surfaces consisting of the topographically altered metallic copper and a relatively small amount of copper oxide thereon. Excellent bonding strengths are achieved with decreased incidence of pink ring formation as compared to conventional processes utilizing copper oxide for adhesion promotion. In addition, the copper ion containing solutions resulting from the controlled dissolution and removal of copper oxide can be economically utilized in formulating electroless copper plating baths.

A novel bipolar cell is described together with a method for employing the same in the electrowinning of heavy metals (copper, nickel, cobalt and the like) from baths such as etchants, electroless plating baths and the like. In a particular application, the bipolar cell is used to regenerate a chloride-based ammoniacal copper etching bath by electrowinning a portion of the copper therein. The regeneration is accomplished without generating any significant amount of gaseous chlorine. The regeneration of the copper etching bath in this manner is used in a closed loop system for maintaining at a substantially constant level the amount of copper present in an operating ammoniacal chloride copper etchant bath.

Process for direct electrolytic regeneration of chloride-based

A composition for stripping tin, and any underlying copper-tin intermetallic, from a copper surface, the composition being an aqueous solution of sulfuric acid and at least one member selected from an inorganic nitrate, preferably ferric nitrate, and nitric acid, and mixtures thereof.

Composition and process for stripping tin from copper surfaces

After the etching away of copper to selectively expose surface areas of insulating resin material in a printed circuit process based upon metal-clad insulating substrate material, the exposed surface areas of insulating material are contacted with a liquid treatment composition effective to soften or swell the resin material such that residual metal species otherwise associated with the surface area are removed or, at the least, become entrapped or encapsulated below a surface of resin, such that the surface insulation resistance afforded by the insulating surface areas of the printed circuit is improved.

Method for improving the surface insulation resistance of printed

After the stripping or etching away of metal to expose surface areas of insulating resin material in a printed circuit process based upon metal-clad insulating substrate material, the exposed surface areas of insulating material are contacted with a liquid treatment composition, comprised of an aqueous acidic solution containing fluoride ion, effective to remove from the surface areas residual metal species otherwise associated therewith, such that the surface insulation resistance afforded by the insulating surface areas of the printed circuit is improved.

Composition and method for improving the surface insulation resistance

A process is described for the direct electrolytic regeneration of chloride-based ammoniacal copper etchants without generating any significant amount of gaseous chlorine. The electrolysis is carried out using an etch resistant metal cathode and an anode which can be carbon, or an etch resistant metal optionally coated with a noble metal oxide. The process can be adapted to a closed loop system for maintaining at a substantially constant level the amount of copper present in an operating ammoniacal chloride etchant bath.

Process for regenerating ammoniacal chloride etchants

An aqueous composition for stripping tin or solder, as well as any underlying copper-tin alloy, from copper surfaces, containing an alkane sulfonic acid, preferably methane sulfonic acid, ferric nitrate, and a source of chlorate ion. The composition effects stripping without any appreciable formation of sludge or precipitate or suspended particles, and the chlorate component enables significant reduction in the concentration of alkane sulfonic acid otherwise needed for the stripping. Also described are stripping compositions containing a source of chlorate ion and an acid for solubilizing stripped tin or tin-lead, such as alkane sulfonic acid, acetic acid, formic acid and the like.

Composition and method for stripping tin or tin-lead alloy from copper

A composition for stripping tin or solder, as well as any underlying copper-tin alloy, from copper surfaces, containing an alkane sulfonic acid, preferably methane sulfonic acid, and an inroganic nitrate, preferably ferric nitrate. The composition effects stripping without any appreciable formation of sludge or precipitate or suspended particles.

Composition containing alkane sulfonic acid and ferric nitrate for

An aqueous solution of alkane sulfonic acid and inorganic nitrate used to strip metals from substrate surfaces, such as in stripping tin or tin-lead from copper surfaces, is regenerated by subjecting it to electrolysis to case dissolved stripped metals therein to deposit in metallic form on the surfaces of a cathode.

Electrolytic method for regenerating tin or tin-lead alloy stripping

The etching rate of an alkaline ammonium copper etching bath is accelerated by inclusion therein of an etchant accelerating amount of a mixture comprising an ammonium halide, a water-soluble salt containing sulfur, selenium or tellurium in the anion, an organic thio compound containing the group ##STR1## and, optionally, a water-soluble salt of a noble metal (e.g. silver).

Copper etchant compositions

Printed circuit boards having copper circuit patterns coated with an adhesion promoter (e.g., copper oxide, tin) are subjected to the action of an aqueous chromic acid solution prior to incorporation in a multi-layer board by interposing layers of semi-cured polymeric non-conductive material between the individual boards and laminating the assembly using heat and pressure. The chromic acid treatment serves to improve adhesion between the layers and, in particular, to overcome or minimize the 'pink ring' effect which is frequently observed around holes drilled through multilayer boards.

Growing community of inventors

Waterbury, CT, United States of America

John L Cordani