Morton International, Inc.

Shipley Company LLC

Charles R Keil

Randall W Kautz

Osvaldo Novello

Vinai Ming Tara

James J Briguglio

Roberto Stanich

Edward J Reardon, Jr

An improved method of and apparatus that is continuously automatically operative in an in-line system is described for applying under vacuum, heat and mechanical pressure a dry film photoresist-forming layer to printed circuit boards () that already have been prelaminated by the loose application thereto of the dry film resist as discrete cut sheets within the confines of the surface of the boards whereby a laminate without entrapped air bubbles and closely conforming to the raised circuit traces and irregular surface contours of the printed circuit board is obtained. Featured is a conveyorized vacuum applicator () comprising two independent vacuum lamination chambers () in end-to-end relation. The first vacuum chamber operates at ambient temperature to draw off all of the air entrapped between the dry film resist and the surface of the printed circuit board at conditions that do not result in premature tacking of the dry film to the surface of the board. Then, in the second vacuum chamber, the photoresist-forming layer is immediately laminated to the printed circuit board under heat and mechanical pressure. The forgoing reduces or eliminates common lamination defects such as premature resist tacking and the attendant need to repair or rework the printed circuit board.

Conveyorized vacuum applicator and method of applying a dry film resist to a printed circuit board

An improved method of and apparatus that is continuously automatically operative in an in-line system is described for applying under heat, vacuum and mechanical pressure a dry film photoresist-forming layer to printed circuit boards ( ) that already have been prelaminated by the loose application thereto of the dry film resist as discrete cut sheets within the confines of the surface of the boards whereby a laminate without entrapped air bubbles and closely conforming to the raised circuit traces and irregular surface contours of the printed circuit board is obtained. Featured is a conveyorized vacuum laminator ( ) comprising heated upper and lower platens ( ) adapted to be moved into sealing engagement to form a vacuum lamination chamber ( ), and disposed between the platens are two independent belt conveyor systems ( ) that act as heat shields to prevent the printed circuit board and the loosely applied dry film from being heated up too rapidly in the vacuum chamber by the residual heat given off by the upper and lower platens before the film can be completely evacuated. This prevents premature tacking of the dry film to the board and enables all of the air entrapped between the film and the board surface to be drawn off before the application of heat and mechanical pressure, so as to ensure complete conformance of the dry film around the circuit traces and surface contours.

An improved method of and apparatus that is continuously automatically operative in an in-line system is described for applying under vacuum, heat and mechanical pressure a dry film photoresist-forming layer to printed circuit boards ( ) that already have been prelaminated by the loose application thereto of the dry film resist as discrete cut sheets within the confines of the surface of the boards whereby a laminate without entrapped air bubbles and closely conforming to the raised circuit traces and irregular surface contours of the printed circuit board is obtained. Featured is a conveyorized vacuum applicator ( ) comprising two independent vacuum lamination chambers ( ) in end-to-end relation. The first vacuum chamber operates at ambient temperature to draw off all of the air entrapped between the dry film resist and the surface of the printed circuit board at conditions that do not result in premature tacking of the dry film to the surface of the board. Then, in the second vacuum chamber, the photoresist-forming layer is immediately laminated to the printed circuit board under heat and mechanical pressure. The forgoing reduces or eliminates common lamination defects such as premature resist tacking and the attendant need to repair or rework the printed circuit board.

A binder polymer is a styrene/maleic anhydride copolymer in which the maleic anhydride residues are mono-esterified to between about 50 and about 65 mole percent of an alkyl, aryl, cycloalkyl, alkaryl, or arylalkyl alcohol having a molecular weight greater than 100, to between about 15 and about 50 mole percent of a C.sub.1 -C.sub.3 -alkyl alcohol, and to at least about 80 mole percent total. The polymer has between about 45 and about 65 mole percent styrene residues and between about 35 and about 55 mole percent maleic anhydride residues, a weight average molecular weight of between about 80,000 and about 200,000, and an acid number of between about 170 and about 220.

Esterified styrene/maleic anhydride polymer

A photoimageable composition, useful as a photoresist for forming a printed circuit board, is both alkaline aqueous developable but, subsequent to exposure and development, is processable in highly alkaline environments, such as additive plating baths and ammoniacal etchants. The photoimageable composition comprises A) between about 25 and about 75 wt % of a binder polymer, B) between about 20 and about 60 wt % of a photopolymerizeable material which is a multifunctional photopolymerizeable monomer or short chain oligomer, and C) between about 2 and about 20 wt % of a photoinitiator chemical system, the weight percentages being based on the total weight of components A)-C). The improvement is the use in the photoimageable composition of a binder polymer A) which is a styrene/maleic anhydride copolymer in which the maleic anhydride residues are mono-esterified to between about 50 and about 65 mole percent of an alkyl, aryl, cycloalkyl, alkaryl, or arylalkyl alcohol having a molecular weight greater than 100, to between about 15 and about 50 mole percent of a C.sub.1 -C.sub.3 -alkyl alcohol, and to at least about 80 mole percent total. The polymer has between about 45 and about 65 mole percent styrene residues and between about 35 and about 55 mole percent maleic anhydride residues, a weight average molecular weight of between about 80,000 and about 200,000, and an acid number of between about 170 and about 220.

Esterified styrene/maleic anhydride polymer and polymer-containing

In a method of providing a resist pattern on a substrate surface, a layer of photoimageable composition is applied to a substrate, which photoimageable composition provides a tack-free surface. The photoimageable composition comprises: A) between about 25 and about 75 wt % of a binder polymer, B) between about 20 and about 60 wt % of a photopolymerizeable material which is a multifunctional photopolymerizeable monomer or short chain oligomer, and C) between about 2 and about 20 wt % of a photoinitiator chemical system (the weight percentages are based on the total weight of components A)-C)). The binder polymer A) comprises a backbone formed of between about 45 and about 65 mole percent of monomers which are selected from the group i) consisting of styrene, C.sub.1 14 C.sub.6 -substituted styrene and mixtures thereof and between about 35 and about 55 mole percent of monomers which are selected from the group ii) consisting of maleic anhydride, alkyl-substituted maleic anhydride, aromatic-substituted maleic anhydride and mixtures thereof. Monomers of group ii) provide anhydride groups to the backbone of the polymer. The anhydride groups are mono-esterified to between about 50 and about 65 mole percent with an alkyl, aryl, cycloalkyl, alkylaryl, or arylalkyl first alcohol a) having a molecular weight of at least 100 or mixture of first alcohols a); and the anhydride groups are mono-esterified to between about 15 and about 50 mole percent of a C.sub.1 -C.sub.3 -alkyl second alcohol b) or mixture of second alcohols b). Polymer A) is mono-esterified to at least about 80 mole percent total of its anhydride groups. The polymer has a weight average molecular weight of between about 80,000 and about 200,000, and an acid number of between about 170 and about 220. The photoimageable composition layer is directly contacted with patterned artwork, exposed through the artwork, and developed in alkaline aqueous solution to remove non-exposed portions thereof.

Method of producing a resist pattern by contact imaging a photoimageable

A photoimageable composition, useful as a photoresist for forming a printed circuit board, is both alkaline aqueous developable but, subsequent to exposure and development, is processable in highly alkaline environments, such as additive plating baths and ammoniacal etchants. The photoimageable composition is tack-free and is resistance to polymerization inhibition by oxygen, and is therefore particularly suitable for contact printing. The photoimageable composition comprises A) between about 25 and about 75 wt % of a binder polymer, B) between about 20 and about 60 wt % of a photopolymerizeable material which is a multifunctional photopolymerizeable monomer or short chain oligomer, and C) between about 2 and about 20 wt % of a photoimageable chemical system, the weight percentages being based on the total weight of components A)-C). The improvement is the use in the photoimageable composition of a binder polymer A) which is a styrene/maleic anhydride copolymer in which the incorporated maleic anhydride units are mono-esterified to between about 50 and about 65 mole percent of an alkyl, aryl, cycloalkyl, alkaryl, or arylalkyl alcohol having a molecular weight greater than 100, to between about 15 and about 50 mole percent of a C.sub.1 -C.sub.3 -alkyl alcohol, and to at least about 80 mole percent total. The polymer has between about 45 and about 65 mole percent incorporated styrene units and between about 35 and about 55 mole percent incorporated maleic anhydride units, a weight average molecular weight of between about 80,000 and about 200,000, and an acid number of between about 170 and about 220.

Growing community of inventors

Foothill Ranch, CA, United States of America

Charles R Keil