Conformal coatings cured with actinic radiation

• US 5,155,143 A
• Filed: 03/25/1991
• Issued: 10/13/1992
• Est. Priority Date: 12/19/1985
• Status: Expired due to Term

• Current Assignee: Specialty Coating Systems Inc.
• Original Assignee: Union Carbide Chemicals & Plastics Technology Corporation (Dow, Inc.)
• Inventors: Koleske, Joseph V.
• Primary Examiner(s): McCamish, Marion E.
• Assistant Examiner(s): KOECKERT JR, ARTHUR
• Application Number:
  US07/674,168
• Time in Patent Office: 568 Days
• Field of Search: 522/170, 522/31, 528/26, 528/27, 528/361
• US Class Current: 522/31
• CPC Class Codes: C08G 59/24 carbocyclic
• CPC Class Codes: C08G 59/68 characterised by the catalysts used
• CPC Class Codes: C08G 65/06 Cyclic ethers having no atoms other than carbon and hydrogen outside the ring
• CPC Class Codes: C08L 2666/14 Macromolecular compounds according to C08L59/00 - C08L87/00; Derivatives thereof
• CPC Class Codes: C08L 63/00 Compositions of epoxy resins; Compositions of derivatives of epoxy resins
• CPC Class Codes: C09D 163/00 Coating compositions based on epoxy resins; Coating compositions based on derivatives of epoxy resins
• CPC Class Codes: H05K 2201/09872 Insulating conformal coating foil encapsulation H05K2203/1311
• CPC Class Codes: H05K 3/287 Photosensitive compositions
• CPC Class Codes: Y10S 428/901 Printed circuit
• CPC Class Codes: Y10S 428/913 Material designed to be responsive to temperature, light, moisture
• CPC Class Codes: Y10T 428/31511 Of epoxy ether

Abstract

A photocurable composition based on a cycloaliphatic polyepoxide, a poly(tetramethylene oxide)polyol and photoinitiator; and a printed circuit board having as a conformal coating thereon, the cured product of the photocurable composition.

Claims

1. A photocurable composition consisting essentially of a cycloaliphatic polyepoxide, a poly(tetramethylene oxide)polyol, and a photoinitiator, the cured product of said composition being moisture resistant and having an electrical insulation resistance of greater than about 2.5×

10¹² ohms.

2. The cured product of the composition defined in claim 1.

15. A photocurable composition as defined in claim 2 consisting essentially of 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexane carboxylate, a dihydroxy functional (tetramethylene oxide)polyol having a molecular weight of about 1,000, an onium salt photoinitiator, and a silicone-ethylene oxide copolymer surfactant having the formula:

##STR13## said surfactant being present in an amount of about 0.05 to about 1.0 percent.

3. A photocurable composition consisting essentially of a cycloaliphatic diepoxide in an amount of about 60 to about 89 parts by weight, a poly(tetramethylene oxide)polyol in an amount of about 10 to about 35 parts by weight and an onium photoinitiator in an amount of about 1 to about 5 parts by weight, the cured product of said composition being moisture resistant and having an electrical insulation resistance of greater than about 2.5×

10¹² ohms.

4. A composition as defined in claim 3 wherein said diepoxide is 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexane carboxylate.

5. A composition as defined in claim 3 wherein said diepoxide is bis(3,4-epoxycyclohexylmethyl) adipate.

6. A composition as defined in claim 3 wherein said diepoxide is 2-(3,4-epoxycyclohexyl-5,5-spiro 3,4-epoxy)cyclohexane-meta-dioxane.

7. A composition as defined in claim 3 wherein said diepoxide is a mixture of 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexane carboxylate, bis(3,4-epoxycyclohexylmethyl) adipate and 2-(3,4-epoxycyclohexyl-5,5-spiro 3,4-epoxy)cyclohexane-meta-dioxane.

8. A composition as defined in claim 3 wherein said polyol has a molecular weight of 600 to 3,000.

9. A composition as defined in claim 3 wherein said composition contains a reactive monoepoxide diluent.

10. A composition as defined in claim 9 wherein said diluent is vinyl cyclohexene monoepoxide.

11. A composition as defined in claim 3 wherein said photoinitiator is a hexafluoroantimonate salt.

12. A composition as defined in claim 11 wherein said salt is an aryl sulfonium hexafluoroantimonate salt.

13. A composition as defined in claim 3 wherein said composition contains a silicone-ethylene oxide copolymer surfactant having the formula:

##STR12## said surfactant being present in an amount of about 0.05 to about 1.0 percent.

14. A composition as defined in claim 3 wherein said composition contains a fluorescent dye.

16. A photocurable composition consisting essentially of a cycloaliphatic polyepoxide, a poly(tetramethylene oxide)polyol, a surfactant and a photoinitiator, the cured product of said composition being moisture resistant and having an electrical insulation resistance greater than about 2.5×

10¹² ohms.