Kollmorgen Corporation

Amp-akzo Corporation

Photocircuits Corporation

Thomas S Kohm

Louis J Stans

James Tullo

A dual air knife assembly for removing excess solder and leveling any remaining solder on a passing circuit board with a gas from a gas source in accordance with the present invention includes a first and second air knife. The first air knife has a first passage with a first inlet adapted to connect to the gas source and a first outlet adapted to be positioned adjacent the passing circuit board. The second air knife has a second passage with a second inlet connected to the gas source and a second outlet adapted to be positioned adjacent the passing circuit board. The first air knife is adapted to be positioned substantially perpendicular to the circuit board and the second air knife is adapted to be positioned at an angle less than 90 degrees and preferably between 20 and 60 degrees to the circuit board. The dual air knife assembly may include a spacer which separates the a first and second air knife and is recessed from the outlets of the a first and second air knife to create an expansion chamber. The distance the first and second outlets are from the passing circuit board and the temperature and pressure of the gas exiting from the a first and second air knife should all be substantially the same. Typically, the dual air knife assembly is used in a soldering system which includes a conveyor, a flux station, and a solder station. The dual air knife assembly is used in a process referred to as 'hot air solder levelling' to remove excess solder and more evenly distribute any remaining solder. A pair of dual air knife assemblies may be used in another soldering system where excess solder is removed and any remaining solder is levelled on both sides of a circuit board.

Dual air knife for hot air solder levelling

This invention concerns a method of manufacturing printed wiring boards by electrolessly plating copper on a precatalyzed base material which contains a polymeric resin, woven glass cloth reinforcement and a noble metal catalyst on clay support to precatalyze the base material for electrolessly depositing copper. The improvement comprises providing in the polymeric resin, a phenolic resin component and a silicate filler. The silicate filler is present in an amount between 30 and 100 part per hundred parts of the polymeric resin, and in an amount sufficient to provide a take time for the initiation of electroless copper deposition at least two times faster than a comparable precatalyzed base material without the silicate filler and phenolic resin.

Printed circuits and base materials precatalyzed for metal deposition

A base material for printed wiring boards is formed by laminating together layers of prepregs of woven cloth impregnated with a thermosetting polymeric resin varnish. The varnish has an inorganic filler which is present in an amount sufficient to provide the base material with an average coefficient of thermal expansion along its Z-axis between 30.degree. C. and 270.degree. C. which is equal to or less than the coefficient of thermal expansion of copper from 30.degree. C. to 270.degree. C. plus the maximum elongation at 270.degree. C. of copper suitable for forming a conductive pattern on hole walls of printed wiring boards. Printed wiring boards manufactured on the base material by additive or subtractive processes are resistant to failure from thermal stress or thermal cycling.

Printed circuits and base materials having low Z-axis thermal expansion

A method of applying a coating to the inner layers of multilayer boards made of copper. The cured coating is capable of maintaining adhesion without outgassing for at least 10 seconds at 250.degree. C. It can be adhesion promoted for adherent electroless metal deposition with a chromic acid adhesion promotion solution. The coating composition comprises the product of reacting between 20 to 60% of a poly(vinyl acetal) resin with 80 to 40% of a phenolic resin in the presence of an acidic catalyst and a coupling agent having at least two amino substituted aromatic groups covalently bonded to a titanium or zirconium central atom via an oxygen containing linkage. The coating composition is applied to a metallic oxide film on the surface of the copper substrate.

Method of applying adherent coating on copper

A multilayer printed wiring board is described having (1) an inner layer conductive pattern on an organic insulating base material, (2) a poly(vinyl acetal)-phenolic resin coating containing an amine substituted organic zirconate or titanate coupling agent, (3) a dielectric insulating layer, (4) a bonding composition capable of being adhesion promoted for electroless metal deposition comprising a phenolic resin having at least two methylol groups and substantially free of methyl ether groups, a heat resistant aromatic or cyclic resin having functional groups capable of reacting with the methylol groups without the evolution of water, and (5) an outer conductive pattern, the multilayer board being capable of withstanding at least five soldering cycles of at least 255.degree. C. for 2 seconds without blistering or delamination. Processes for manufacturing the multilayer board are also described.

Multilayer printed wiring boards

A primer coating composition suitable for coating the inner layers of multilayer boards is disclosed. The cured coating is capable of maintaining adhesion without outgassing for at least 10 seconds at 250.degree. C. It can be adhesion promoted for adherent electroless metal deposition with a chromic acid adhesion promotion solution. The coating composition comprises the product of reacting between 20 to 60% of a poly(vinyl acetal) resin with 80 to 40% of a phenolic resin in the presence of an acidic catalyst and a coupling agent having at least two amino substituted aromatic groups covalently bonded to a titanium or zirconium central atom via an oxygen containing linkage.

Growing community of inventors

Huntington, NY, United States of America

Thomas S Kohm