US4479983A
Expired / Lapsed
US
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Method and composition for applying coatings on printed circuit boards
Assignee: International Business Machines Corp
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Filing: 1983-01-07
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Granted: 1984-10-30
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Expires: 2003-01-07
Abstract
Abstract A coating is produced by a method including a screen printing of a photopolymerizable composition on a printed circuit board, illuminating said composition to partially polymerize it and bake it to complete the polymerization. The composition used by said method contains a reaction product of a monoethylenically unsaturated carboxylic acid with a material of the group of epoxy resin and epoxidized novolak, a phenoxy resin, a thickening agent, a polyethylenically unsaturated compound, a photo-initiator and a solvent. The coating produced according to this invention is used as solder mask.
Inventors
- 👤 Bernd K. Appelt
- 👤 George P. Schmitt
- 👤 John F. Shipley
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 07:24
CPC Classifications
C; C08; C08F; C08F299/00; C08F299/02; C08F299/026; C08F299/028; B; B23; B23K; B23K35/00; B23K35/22; B23K35/224; H; H05; H05K; H05K3/00; H05K3/22; H05K3/28; H05K3/285; H05K3/287; H05K2203/00; H05K2203/11; H05K2203/1105
Claims Analysis
Total Claims: 27
Claim 1
Independent Claim
148 words
Method of forming a solder mask on a high density printed circuit board comprising: (a) preparing a photopolymerizable composition consisting of a phenoxy resin, a thickening agent, a polyethylenically unsaturated compound, a photoinitiator, a solvent, and a reaction product of a monoethylenically unsaturated carboxylic acid with a material of the group consisting of bis-phenol A-based epoxy resins and epoxidized novolaks, and wherein the ingredients are mixed according to the viscosity of the composition required for a desired screenability and curability of said composition, and the desired thickness and hardness of the solder mask to be produced, (b) screen printing said photopolymerizable composition onto a printed circuit board, (c) blanket illuminating said applied composition in order to partially polymerize it to at least the point at which bleeding in of said applied composition is inhibited and resolution is retained, and (d) baking said applied composition to complete the polymerization.
Claim 2
Dependent Claim
148 words
Method of forming a solder mask on a high density printed circuit board comprising: (a) preparing a photopolymerizable composition consisting of a phenoxy resin, a thickening agent, a polyethylenically unsaturated compound, a photoinitiator, a solvent, and a reaction product of a monoethylenically unsaturated carboxylic acid with a material of the group consisting of bis-phenol A-based epoxy resins and epoxidized novolaks, and wherein the ingredients are mixed according to the viscosity of the composition required for a desired screenability and curability of said composition, and the desired thickness and hardness of the solder mask to be produced, (b) screen printing said photopolymerizable composition onto a printed circuit board, (c) blanket illuminating said applied composition in order to partially polymerize it to at least the point at which bleeding in of said applied composition is inhibited and resolution is retained, and (d) baking said applied composition to complete the polymerization.
Claim 3
Dependent Claim
86 words
Method according to claim 1, wherein said coating is prepared from a composition consisting of a reaction product of a monoethylenically unsaturated carboxylic acid with a material of the group epoxy resin and epoxidized novolak, a phenoxy resin, a thickening agent, a polyethylenically unsaturated compound, a photo-initiator and a solvent, and wherein the ingredients are mixed according to the viscosity of the composition required for a desired screenability, and the curability of the composition, and the desired thickness and hardness of the coating to be produced.
Claim 4
Dependent Claim
37 words
Method according to claim 2, wherein as thickening agent colloidal silica, as polyethylenically unsaturated compound tri-methylolpropane tri-acrylate (TMPTA), as photoinitator tert-butylanthraquinone (TBA), as mono ethylenically unsaturated carboxylic acid acrylic acid and as solvent cellosolve acetate are used.
Claim 5
Dependent Claim
18 words
Method according to claim 3, wherein an anhydride of a dicarboxylic acid is added to the screenable composition.
Claim 6
Dependent Claim
72 words
Method according to claim 4, wherein said composition is mixed of between about 20 to about 50% by weight of acrylated epoxy resin, between about 28 to about 48% by weight of phenoxy resin, between about 2 and about 6% by weight of colloidal silica, between about 5 and about 15% by weight of TMPTA, and between about 0.5 and about 1.5% by weight of TBA, with the rest consisting of solvent.
Claim 7
Dependent Claim
54 words
Method according to claim 5, wherein said composition is mixed of about 30% by weight of an acrylated epoxy resin, about 38% by weight of a phenoxy resin, about 3% by weight of Cab-O-Sil, about 8% by weight of TMPTA, about 0.5% by weight of TBA and about 20,5% by weight of a solvent.
Claim 8
Dependent Claim
93 words
Method according to claim 4, wherein said composition is mixed of between about 31 and about 55% by weight of an acrylated epoxidized novolak, between about 5 and about 11% by weight of a phenoxy resin, between about 14 and about 20% by weight of nadic methyl anhydride as liquid anhydride of a carboxylic acid, between about 4 and about 5.5% by weight of colloidal silica, between about 4 and about 12% by weight of TMPTA, and between about 0.5 to about 1.5% by weight of TBA, with the rest consisting of solvent.
Claim 9
Dependent Claim
60 words
Method according to claim 7, wherein said composition is mixed of about 42% by weight of acrylated epoxidized novolak, about 8% by weight of phenoxy resin, about 15.5% by weight of nadic methyl anhydride, about 4.5% by weight of colloidal silica, about 8% by weight of TMPTA, about 1% by weight of TBA and about 21% by weight of solvent.
Claim 10
Dependent Claim
85 words
Method according to claim 8, wherein said material of the group of epoxy resin and epoxidized novolak is dissolved in a solvent and combined with the monoethylenically unsaturated carboxylic acid, wherein the two compounds are allowed to react at about 65° C. for about 24 hours, wherein the reaction product is combined with a premix of the phenoxy resin, TMPTA and TBA and wherein the colloidal silica is sheared into the mixture and wherein the produced composition is screen printed onto said printed circuit board.
Claim 11
Dependent Claim
46 words
Method according to claim 9, wherein the relative amount of the acrylic acid to the epoxy resin or the epoxidized novolak respectively is sufficient to react stoichiometrically with about 50 to about 75% of the epoxide functionality of this epoxy resin or this epoxidized novolak respectively.
Claim 12
Dependent Claim
27 words
Method according to claim 10, wherein the applied coating is illuminated with UV light having an intensity of 1.25 to 5 watts/cm 2 of the coating surface.
Claim 13
Dependent Claim
26 words
Method according to claim 11, wherein said coating is baked at temperatures between about 100° and about 180° C. for about 20 to about 40 minutes.
Claim 14
Dependent Claim
35 words
Method according to claim 12, wherein the coating is illuminated with an intensity of about 3 watts/cm 2 of the coating surface and baked at a temperature of about 140° C. for about 30 minutes.
Claim 15
Dependent Claim
49 words
Composition for producing coatings on printed circuit boards consisting of a phenoxy resin, a thickening agent, a polyethylenically unsaturated compound, a photoinitiator, a solvent and a reaction product of a monoethylenically unsaturated carboxylic acid with a material of the group consisting of bis-phenol A-based epoxy resins and epoxidized novolaks.
Claim 16
Dependent Claim
49 words
Composition for producing coatings on printed circuit boards consisting of a phenoxy resin, a thickening agent, a polyethylenically unsaturated compound, a photoinitiator, a solvent and a reaction product of a monoethylenically unsaturated carboxylic acid with a material of the group consisting of bis-phenol A-based epoxy resins and epoxidized novolaks.
Claim 17
Dependent Claim
46 words
Composition according to claim 14, wherein said thickening agent is colloidal silica, said polyethylenically unsaturated compound is tri-methyl propane triacrylate (TMPTA), said photoinitiator is tert.-butyl anthraquinone (TBA), said monoethylenically unsaturated compound is acrylic acid and said solvent is cellosolve acetate, methyl ethyl ketone or butyl carbitol.
Claim 18
Dependent Claim
13 words
Composition according to claim 15, also containing an anhydride of a dicarboxylic acid.
Claim 19
Dependent Claim
24 words
Composition according to claim 16, wherein said monoethylenically unsaturated carboxylic acid is selected from the group of acrylic acid, methacrylic acid and crotonic acid.
Claim 20
Dependent Claim
46 words
Composition according to claim 17, wherein the relative amounts of monoethylenically unsaturated acid to the epoxy resin or the epoxidized novolak respectively is sufficient to react stoichiometrically with about 50 to about 100% of the epoxide functionality of this epoxy resin or this epoxidized novolak respectively.
Claim 21
Dependent Claim
42 words
Composition according to claim 18, wherein the relative amount of monoethylenically unsaturated acid to said epoxy resin or said epoxidized novolak respectively is sufficient to react with about 75% of the epoxide functionality of said epoxy resin or said epoxidized novolak respectively.
Claim 22
Dependent Claim
69 words
Composition according to claim 19, wherein the composition contains between about 20 and about 50% by weight of acrylated epoxy resin, between about 28 and about 48% by weight of phenoxy resin, between about 2 and about 6% by weight of colloidal silica, between about 5 and about 15% by weight of TMPTA, and between about 0.5 and 1.5% by weight of TBA with the rest consisting of solvent.
Claim 23
Dependent Claim
47 words
Composition according to claim 20, containing about 30% by weight of acrylated epoxy resin, about 38% by weight of phenoxy resin, about 3% by weight of colloidal silica, about 8% by weight of TMPTA, about 0.5% by weight of TBA and about 20.5% by weight of solvent.
Claim 24
Dependent Claim
84 words
Composition according to claim 21, containing between about 31 and about 55% by weight of acrylated epoxidized novolak, between about 5 and about 11% by weight of phenoxy resin, between about 14 and 20% by weight of nadic methyl anhydride as liquid anhydride of the carboxylic acid, between about 4 to about 5.5% by weight of colloidal silica, between about 4 and about 14% by weight of TMPTA, and between about 0.5 and about 1.5% by weight of TBA with the rest being solvent.
Claim 25
Dependent Claim
55 words
Composition according to claim 22, containing about 42% by weight of acrylated epoxidized novolak, about 8% by weight of phenoxy resin, about 15.5% by weight of nadic methyl anhydride, about 4.5% by weight of colloidal silica, about 8% by weight of TMPTA, about 1.0% by weight of TBA and about 21% by weight of solvent.
Claim 26
Dependent Claim
31 words
Method according to claim 1, wherein both sides of the printed circuit board are coated with the photopolymerizable composition by screen printing, and exposed to radiation prior to the baking step.
Claim 27
Dependent Claim
24 words
Method according to claim 1, wherein the printed circuit boards are inspected prior to the thermal cure and reclaimed in case of defective coating.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-10-30 | 1988-04-30 | 1988-10-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-10-30 | 1992-04-30 | 1992-10-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-10-30 | 1996-04-30 | 1996-10-30 | $7700.00 | Window Closed / Lapsed |