Macdermid, Incorporated

Other

Raymond A Letize

Peter E Kukanskis

Peter D Gabriele

William R Adams

Ann S Williams

Gary B Larson

John L Cordani

Brian Larson

William J Decesare

Richard C Retallick

Lenora M Toscano

Donna M Kologe

Lucia Justice

Thomas D Murry

David D Sullivan

William R Thomas

A method of stripping silver from a printed circuit board without attacking the underlying base metal. The stripping solution comprises an oxidizing agent, an alkaline pH adjuster, and a silver solubilizing agent. After the silver has been sufficiently removed from the surface of the printed circuit board, the printed circuit board is contacted with a neutralization solution to remove any smut remaining on the surface. The silver stripping solution does not contain cyanide or chromium and does not require the use of anodic current.

Method of stripping silver from a printed circuit board

A process for the manufacture of printed circuit boards is disclosed wherein a plated silver deposit is used both as an etch resist and as a final finish for enhancing the solderability of the copper circuits. An aqueous alkaline etchant which is free of halide ions is proposed as being particularly compatible with the silver etch resist/final finish.

Method for the manufacture of printed circuit boards

A composition and process useful in fabricating circuitry packages with permanent resists is proposed. The proposed composition comprises a carboxy functional resin, an acrylate oligomer, an epoxy functional resin, a butadiene nitrile resin, and a photoinitiator.

Photodefinable dielectric composition useful in the manufacture of

A process is proposed for creating circuitry on the surface of a photoimageable dielectric. Specifically the process uses electroless means with controlled pH and an organosilane conditioning agent to fabricate circuitry and interconnects directly upon the surface of a photoimageable dielectric, such circuitry and interconnects having good adhesion to and coverage of the dielectric surface.

Process for creating circuitry on the surface of a photoimageable

An alkaline solution for the microetching of copper in the course of printed circuit manufacture is provided by combining components which are a source of cupric ion, ammonium hydroxide and/or a source of ammonium ion, and a compound, other than ammonia, which is a chelator for cupric ion in the alkaline environment of the solution. The microetchant composition is stable, brings about a desired microroughening of the copper surface with minimal removal of copper, is easily regenerated, and does not promote pink ring. When an organosilane through-hole conditioning agent is included in the composition, the composition can be used as a means for effecting in one step the microetching and conditioning steps of a printed circuit through-hole metallization process.

Microetchant for copper surfaces and processes for using same

The adhesion between surfaces of polyimide, particularly the through hole surfaces of polyimide-based multilayer laminates used in the fabrication of multilayer printed circuits, is improved by pretreatment of the surfaces with an essentially non-alkaline aqueous permanganate solution.

Method for improving adhesion to polymide surfaces

After the etching away of copper to selectively expose surface areas of insulating material in a printed circuit process based upon copper foil-clad insulating substrate material, the exposed surface areas of insulating material are contacted with an aqueous alkaline permanganate solution to remove from the areas residual metal species associated therewith so as to improve the electrical resistance afforded by those areas in the printed circuit.

Method for improving insulation resistance of printed circuits

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

A method of preparing printed circuit boards is described in which the solder mask is applied over a thin layer of copper oxide covering the copper circuit traces, the copper oxide layer being that which remains after stripping the tin or tin-lead alloy etch resist.

Method for manufacture of printed circuit boards

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

A method of preparing printed circuit boards is described in which the solder mask is applied over a thin layer of copper oxide covering the copper circuit traces, the copper oxide layer being that which remains after stripping the tin or tin-lead allow etch resist.

A two step process is described for selectively stripping tin or tin-lead alloys from a copper substrate without significant loss of copper from the substrate. In a first step the substrate coated with tin or tin-lead alloy is subjected to the action of a first stripping composition which can be any of those known in the art containing a mixture of an oxidant for the metal or metals of said layer and an acceptor for the cation or cations so oxidized. When the stripping has reached the stage at which a thin film of tin remains on the copper substrate the latter is subjected to the action of a second stripping composition which comprises a mixture of an alkali metal hydroxide and an alkali metal chlorite until the film of tin has been removed and replaced by a film of copper oxide. If desired, the latter can be removed by known means such as treatment with aqueous acid. The process represents an improvement over known processes in which, in order to remove the last traces of tin from the copper substrate or to remove the film of tin which in some cases is re-deposited from the stripper composition itself, it is necessary to employ stripping conditions so rigorous that significant loss of copper from the substrate takes place. While the process of the invention is applicable to stripping of tin or tin-lead alloys from copper substrates in a wide variety of contexts, it is of particular application to stripping etch resists from copper substrates after completion of the etching step in formation of a printed circuit board.

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West Haven, CT, United States of America

Raymond A Letize