Mcgean-rohco, Inc.

E.i. Dupont De Nemours and Company

John R Dodd

Brian C Auman

Americus C Vitale

Randal D King

William Robert Corcoran

John Donald Summers

Mark A Guidry

Anthony J Arduengo, Iii

John A Kreuz

Carl W Reinbold

Random, melt-processible copolyimides are disclosed herein. These copolyimides are semicrystalline and exhibit recoverable (semi)crystallinity from their melts. Associated processes, which entail either solution polymerization or melt polymerization, for producing and fabricating these copolyimides into useful articles having a predetermined shape are also disclosed.

Melt-processible, thermoplastic random copolyimides having recoverable crystallinity and associated processes

Segmented, melt-processible, semicrystalline copolyimides are disclosed herein. These polymers are comprised of an amorphous or semicrystalline A segment (soft segment) and a semicrystalline B segment (hard segment), wherein the level of semicrystallinity in the A segment is less than that in the B segment. These copolyimides are semicrystalline and exhibit melting points in the range from about 330-395&deg; C. In preferred embodiments, these copolyimides are end-capped and are crystallizable from their melts (i.e., they exhibit recoverable semicrystallinity). These copolyimides either inherently have suitably low melt visocosities to be melt-processible or can be made to have suitably low melt viscosities to be melt-processible by addition of certain additives. Tailoring of the melting points and glass transition temperatures of these copolyimides can be effected by changing their molecular architecture.

Melt-processible semicrystalline block copolyimides

Acid, electroplating baths having consistent leveler activity contain levelers which are quaternized near-monodisperse polymers of acrylic or methacrylic trialkyl amine esters. The polymers may contain hydroxyalkyl acrylate or methacrylate ester components, unquaternized acrylic or methacrylic amine component as well as other polymeric components.

Polymeric leveling additive for acid electroplating baths

A stabilized spray displacement tin plating process of copper printed circuit innerlayers is disclosed for the manufacture of multilayer printed circuit boards. During prolonged use of spray tin plating, the plating solution becomes saturated with cupurous thiourea complex which precipitates interfering with spray nozzles and other mechanical components. The tin plating solution is stabilized by removing portions from the reservoir before saturation is reached, selectively precipitating the thiourea complex, and returning the remaining solution back to the reservoir. The precipitated cupurous thiourea complex is redissolved in acid and either disposed of by conventional waste treatment or the acid solution can be electrowinned to reclaim copper and oxidize thiourea to form a more acceptable acid solution for waste treatment. Preferably, the thiourea is isolated from the anode during electrowinning, so that the acid thiourea solution formed may be used to partially replenish the tin plating solution in the reservoir. By such periodic removal of the complex, the plating bath is stabilized and its useful life is extended dramatically.

Process for extending the life of a displacement plating bath

An environmentally innocuous effective replacement for thiourea is disclosed for use as a complexing agent in displacement plating processes in which the plating solution is applied to the substrate surface to be plated by immersion or by spraying, cascading, pouring and the like. The replacement complexing agent is an imidazole-2-thione compound having the formula: ##STR1## wherein A and B are the same or different --R--Y groups, wherein R is linear, branched or cyclic alkenyl group containing 1 to 12 carbon atoms and Y is a hydrogen, halogen, cyano, vinyl, phenyl, or ether moiety. Of this class of compounds, 1-methyl-3-propyl-imidazole-2-thione is preferred for immersion tin plating. This class of complexing agents is particularly useful in spray displacement tin plating for the manufacture of printed circuit boards wherein free tin metal is added to the plating solution.

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Wilmington, DE, United States of America

John R Dodd