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Timestamp: 2017-11-20 06:11:13
Document Index: 393470581

Matched Legal Cases: ['arts4', 'art6', 'art2', 'arts4', 'art2', 'art2']

Patent US4499163 - Soldering mask formed from a photosensitive resin composition and a ... - Google Patents
A photosensitive resin composition comprising (a) 20 to 75 parts by weight of a urethane diacrylate or dimethacrylate compound obtained by reacting trimethylhexamethylene diisocyanate and/or isophorone diisocynate dihydric alcohol and an acrylic or methacrylic monoester of a dihydric alcohol, (b) 20...http://www.google.com/patents/US4499163?utm_source=gb-gplus-sharePatent US4499163 - Soldering mask formed from a photosensitive resin composition and a photosensitive element
Publication number US4499163 A
Application number US 06/512,660
Also published as DE3136818A1, DE3136818C2
Publication number 06512660, 512660, US 4499163 A, US 4499163A, US-A-4499163, US4499163 A, US4499163A
Inventors Toshiaki Ishimaru, Katsushige Tsukada, Nobuyuki Hayashi, Shigeru Koibuchi, Asao Isobe
Patent Citations (7), Referenced by (47), Classifications (21), Legal Events (3)
Soldering mask formed from a photosensitive resin composition and a photosensitive element
US 4499163 A
A photosensitive resin composition comprising (a) 20 to 75 parts by weight of a urethane diacrylate or dimethacrylate compound obtained by reacting trimethylhexamethylene diisocyanate and/or isophorone diisocynate dihydric alcohol and an acrylic or methacrylic monoester of a dihydric alcohol, (b) 20 to 75 parts by weight of a linear polymeric compound having a glass transition temperature of about 40° to 150° C., and (c) a sensitizer and/or a sensitizer system which generate free radicals owing to actinic light, is excellent in heat resistance, resistance to thermal shock and solvent resistance, and is suitable for forming a soldering mask. Further, a photosensitive element produced by forming a layer of the above-mentioned composition on a support gives a protective coating film excellent in heat resistance, resistance to thermal shock and solvent resistance, and is particularly suitable for a soldering mask.
1. A photosensitive resin composition forming a soldering mask comprising:
(a) 20 to 75 parts by weight of at least one urethane diacrylate or urethane dimethacrylate compound which has acryloyl or methacryloyl groups in an amount of 1×10-3 to 4.3×10-3 equivalent/g. and which is obtained by reacting
(i) at least one diisocyanate compound selected from the group consisting of trimethylhexamethylene diisocyanate and isophorone diisocyanate,
(ii) a dihydric alcohol, and
(iii) an acrylic or methacrylic monoester of a dihydric alcohol,
(b) 20 to 75 parts by weight of a linear polymer having a glass transition temperature of about 40° to 150° C., and
(c) a sensitizer and/or a sensitizer system which generate free radicals owing to actinic light in an amount of 0.5 to 10% by weight based on the total amounts of components (a) and (b); said composition having been heated to 80° to 200° C. and exposed to actinic light after development by image-wise exposure and treatment with a developing solution.
2. A composition according to claim 1, wherein the diisocyanate compound (i) is trimethylhexamethylene diisocyanate.
11. A composition according to claim 1, which additionally contains
(d) an acrylic or methacrylic ester containing a phosphoric acid group in the molecule in an amount of 0.01 to 5% by weight based on the total amount of components (a) and (b).
12. A composition according to claim 1, which additionally contains antimony trioxide in an amount up to 5% by weight.
13. A photosensitive element forming a soldering mask comprising (I) a layer of a photosensitive resin composition comprising
(ii) a dihydric alcohol and
(b) 20 to 75 parts by weight of a linear polymer having a glass transition temperature of about 40° C. to 150° C., and
(c) a sensitizer and/or a sensitizer system which generate free radicals owing to actinic light in an amount of 0.5 to 10% by weight based on the total amounts of components (a) and (b); said composition having been heated to 80° to 200° C. and exposed to actinic light after development by image-wise exposure and solvent treatment, and (II) a support film supporting said layer.
14. A photosensitive element according to claim 13, wherein the diisocyanate compound (i) in the layer (I) of the photosensitive resin composition is trimethylhexamethylene diisocyanate.
28. A composition according to claim 1, wherein the urethane diacrylate or dimethacrylate compound (A) is obtained by effecting reaction of components (i), (ii) and (iii) at a temperature from 40° to 100° C.
Accordingly, there have been put forward many proposals on a photosensitive resin composition for a photosensitive element good in heat resistance which can be used for forming a soldering mask (for example, Japanese Patent Appln. Kokai (Laid-Open) No. 56018/78 (U.S. Patent Appln. Ser. No. 735,979 filed Oct. 27, 1976 now abandoned), Japanese Patent Appln. Kokoku (Post-Exam Publn) No. 43,092/77 and Japanese Patent Appln. Kokoku (Post-Exam. Publn) No. 44,346/78 (U.S. Patent Appln. Ser. No. 782,378 filed Mar. 29, 1977 now U.S. Pat. No. 4,272,607). The photosensitive resin compositions in these proposals are excellent in heat resistance which is one of the objects of the proposals; however when a thick protective film of 40 μm or more in thickness is formed from the compositions, the film cracks within 5 cycles in a thermal shock test holding at 125° C. then holding at -65° C. repeatingly (MIL-STD-202E method 107D condition B). The thicker the film becomes, the more seriously the film cracks. This becomes a serious problem when the long time reliability of a printed wiring board should be taken into consideration.
(b) 20 to 75 parts by weight of a linear high-molecular (or polymeric) compound having a glass transition temperature of about 40° to 150° C., and
Further, this invention provides a photosensitive element comprising a layer of the photosensitive resin composition mentioned above, i.e., comprising (a) 20 to 75 parts by weight of a urethane di(meth)acrylate compound obtained by reacting (i) isophorone diisocyanate and/or trimethylhexamethylene diisocyanate, (ii) a dihydric alcohol and (iii) a (meth)acrylic monoester of a dihydric alcohol, (b) 20 to 75 parts by weight of a linear high-molecular comound having a glass transition temperature of about 40° to 150° C., and (c) a sensitizer and/or a sensitizer system which generate free radicals owing to actinic light; and a support film supporting said layer.
When the urethane di(meth)acrylate compound of this invention is synthesized, the reaction is usually effected at a temperature from 40° to 100° C., and it is preferable to determine the amounts of the isocyanate compund (i), the dihydric alcohol (ii) and the (meth)acrylic monoester of a dihydric alcohol (iii), so as to effect the reaction so that the isocyanate equivalent of the diisocyanate compound (i) may be almost equal to the alcohol equivalent of the sum of the dihydric alcohol (ii) and the (meth)acrylic monoester of a dihydric alcohol (iii). However, the isocyanate equivalent may be a little over or a little below the alcohol equivalent. When the isocyanate equivalent is a little over the alcohol equivalent, the excess isocyanate groups are finally reacted with a monohydric alcohol such as methanol, whereby the free isocyanate groups can be eliminated.
The present inventors have done various researches to find that a soldering mask formed by using a photosensitive resin composition obtained by the use of a urethane di(meth)acrylate compound (mixture) containing (meth)acryloyl groups in an amount of 1×10-3 to 4.3×10-3 equivalent/g is excellent in balance between the heat resistance and the resistance to thermal shock.
The photosensitive resin composition of this invention contains as an indispensable component a linear high-molecular compound (b) having a glass transition temperature of about 40° to 150° C.
When the glass transition temperature is lower than about 40° C., the heat-resistance of the formed soldering mask is low. When the glass transition temperature exceeds about 150° C., the miscibility of said compound (b) with the urethane di(meth)acrylate compound is lowered, so that it becomes impossible to form a layer of the photosensitive resin composition on a support film or a substrate. As the linear high polymer of the (b) component, there may be used a thermoplastic polymer disclosed in Japanese Patent Appln Kokoku (Post-Exam Publn) No. 15,932/66 (U.S. patent appln. Ser. No. 274,909 filed Apr. 23, 1963) now U.S. Pat. No. 3,261,686. There may be used, for example, vinyl series linear polymers or copolymers, copolyesters, polyamides, vinylidene chloride copolymers, synthetic rubbers, and the like. Vinyl series linear copolymers are preferred from the viewpoint of miscibility with the urethane di(meth)acrylate compound and adhesion between the printed wiring substrate and the layer of a photosensitive resin composition, though vinyl series homopolymers may be used. As the copolymerization component of the linear high-molecular compounds, various vinyl monomers may be used. Suitable examples of the vinyl monomers include methyl methacrylate, butyl methacrylate, ethyl acrylate, styrene, α-methylstyrene, vinyltoluene, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-hydroxyethyl acrylate, acrylic acid, methacrylic acid, glycidyl methacrylate, t-butylaminoethyl methacrylate, 2,3-dibromopropyl methacrylate, 3-chloro-2-hydroxypropyl methacrylate, acrylamide, acrylonitrile, and the like.
Examples of the (meth)acrylic esters containing a phosphoric acid group include PM-1, PM-2, PA-1 and PA-2 in KAYAMER® series manufactured by Nihon Kayaku Co., Ltd., Phosmer M® (acid phosphoxyethyl methacrylate), Phosmer CL® (3-chloro-2-acid phosphoxypropyl methacrylate) manufactured by Fats and Oils Articles Co., Ltd., etc. The content of these (meth)acrylic esters containing in the molecule a phosphoric acid group is preferably 0.01 to 5% by weight based on the total amounts of the above-mentioned (a) urethane di(meth)acrylate compound and (b) linear high-molecular compound.
The exposure and the development treatment after the lamination can be carried out by a conventional method. That is to say, when the support film is not pervious to actinic light, the support film is peeled off and thereafter the imagewise exposure is carried out through a negative mask by using a light source such as a high pressure mercury arc lamp, an ultra-high pressure mercury lamp, or the like. Heat treatment at 50° to 100° C. before and after the exposure is preferable for increasing adhesion between the substrate and the photosensitive resin layer.
The imagewise protective coating film obtained in the manner described above is an anti-corrosive coating film for usual etching, metal plating, and the like, and it becomes a protective coating film having more excellent characteristics by heat treatment at 80° to 200° C. and exposure to actinic light after the development. As to the order of the heat treatment and the exposure to actinic light after the development, either may be the first, and each of them may be carried out by dividing into several steps. The protective coating film obtained by heat treatment and exposure to actinic light after the development is sufficiently resistant to organic solvents such as trichlene, methyl ethyl ketone, isopropyl alcohol, toluene, and the like and is resistant also to an acidic aqueous solution and an aqueous alkali solution. Furthermore, it is excellent in heat resistance and resistance to thermal shock, and hence is suitable as a parmanent protective coating film such as a soldering mask and the like which is required to have reliability for a long time.
(a) Synthesis of a urethane diacrylate compound
The ingredients as mentioned above were placed in a reactor having a capacity of about 5 liters equipped with a thermometer, a stirrer, a condenser, a nitrogen-gas-introducing tube and a dropper which could be heated and cooled, and then ingredient A was heated to 60° C. with stirring. The ingredient B was uniformly added dropwise to the ingredient A in the reactor over a period of about 3 hours while maintaining the reaction temperature at 55° to 65° C. After the addition of the ingredient B, the resulting mixture was maintained at a temperature of 55° to 65° C. for about 2 hours, after which the ingredient C was uniformly added thereto dropwise at a temperature of about 55° to 65° C. over a period of about 3 hours. After the addition of the ingredient C, the reaction temperature was gradually raised to 80° C. over a period of about 5 hours. Thereafter, the temperature was lowered to 60° C., after which the ingredient D was added to the reaction mixture, and the thus obtained mixture was continuously stirred for about 1 hour to give a solution (I) of a urethane diacrylate compound which contained 70 % of nonvolatile matters.
______________________________________The solution (I) of a urethane                  70 parts (49diacrylate compound obtained                  parts in termsin the manner described above                  of non-volatile                  matters)Methyl methacrylate-methacrylic                  47 partsacid-tetrahydrofurfuryl meth-acrylate (78/2/20; weightratio) copolymer (having amolecular weight of about150,000 and a glass transitiontemperature of about 95° C.)Benzophenone           2.7 partsMichler's ketone       0.3 partsp-Methoxyphenol        0.1 partCrystal violet         0.1 partMethyl ethyl ketone    80 parts______________________________________
A solution of a photosensitive resin composition was prepared by mixing the above-mentioned ingredients and then applied to a polyimide film of about 50 μm in thickness, and then dried at room temperature for 20 minutes, at 80° C. for 10 minutes and then at 105° C. for 5 minutes to obtain a photosensitive element in which the thickness of the layer of the photosensitive resin composition was about 60 μm.
Six test substrates having a copper pattern shown in FIG. 1 were obtained by imagewise etching of a laminate faced with glass epoxy copper in which the thickness of its substrate was 1.6 mm and the thickness of the copper foil was 1.8 μm. In FIG. 1, numeral 1 shows a copper pattern part; numeral 2 shows an exposed part of the substrate; and the unit of the figures is mm. The photosensitive element obtained in above (b) was laminated on each of the test substrates by using an A-500 type laminater manufactured by Akebono Industry Co., Ltd. After the lamination, the polyimide film as a support film was peeled off, and the test substrates were exposed at 900 mJ/cm2 by means of a Phenix 3000 type exposing machine manufactured by ORC Factory Co., Ltd. by using a negative mask for test shown in FIG. 2. In FIG. 2, numeral 3 shows an opaque part of the negative mask; numeral 4 shows a transparent part of the negative mask; and the unit of the figures is mm. After the exposure, the test substrates were allowed to stand for 30 minutes, and then subjected to spray development at 20° C. for 90 seconds by using 1,1,1-trichloroethane. After the development, they were heated and dried at 80° C. for 10 minutes and then irradiated at 2.5 J/cm2 by using an ultraviolet light irradiating equipment manufactured by Toshiba Denzai Co., Ltd.
Thereafter, it was heat-treated at 150° C. for 30 minutes.
Four of the six test substrates on which a protective coating film was thus formed were immersed in isopropanol, toluene, trichlene, or a 10% aqueous hydrochloric acid solution, all at 25° C., respectively, for 10 minutes to find that the formed protective coating film underwent no change.
When another one of the test substrates was immersed in a soldering bath at 255° C. to 265° C. for 30 seconds, its protective coating film was so stable that it did neither crack nor peel off from the substrate, and therefore it was found to be sufficiently usable as a soldering mask.
The remaining one test substitute was subjected to soldering treatment in a soldering bath at 255° to 265° C. for 3 seconds by using a rosin series flux A-226 (manufactured by Tamura Kaken Co., Ltd.), and then subjected to the thermal shock test of 50 cycles under MIL-STD-202E method 107D condidtion B (-65° C. for 30 minutes ⃡ ordinary temperature for 5 minutes or less ⃡125° C. for 30 minutes) to find that its protective coating film did not crack and was greatly excellent in reliability for a long time.
______________________________________The urethane diacrylate com-                   40     partspound (II) obtained by theabove-mentioned processMethyl methacrylate-methyl                   57     partsacrylate-2-hydroxyethylmethacrylate-acrylonitrile(80/10/5/5 weight ratio)copolymer (having a molecularweight of about 100,000 and aglass transition temperatureof about 90° C.)Benzophenone            2.7    partsMichler's ketone        0.3    partp-Methoxyphenol         0.1    partVictoria pure blue      0.05   partMethyl ethyl ketone     80     partsToluene                 40     parts______________________________________
A solution 10 of a photosensitive resin composition prepared from the above recipe was uniformly applied to a polyethylene terephthalate film 16 of 25 μm in thickness by using an apparatus shown in FIG. 3, and then dried in a hot-air convection dryer 11 at 80° to 100° C. for about 10 minutes. The thickness after drying of the layer of the photosensitive resin composition was about 100 μm. A polyethylene film 17 of about 25 μm in thickness was stuck as a covering film on the layer of the photosensitive resin composition as shown in FIG. 3.
The photosensitive element obtained in the above was laminated with heating under pressure on printed wiring boards for test (having a glass epoxy substrate and a thickness of 1.6 mm) in which a copper pattern (copper thickness: about 70 μm) shown in FIG. 1 had been formed, by using a vacuum laminater manufactured by Hitachi Chemical Co., Ltd. (degree of vacuum: 30 mmHg, lamination temperature: 100° C., lamination speed: 2 m/min.). After the lamination, the printed wiring boards were heated at 60° C. for 5 minutes, allowed to stand at room temperature for 3 hours, and then exposed at 150 mJ/cm2 through a negative mask for test shown in FIG. 2, as in Example 1-c).
After the exposure, the boards were heated at 80° C. for 5 minutes and then allowed to stand at room temperature for 20 minutes, after which the support film was peeled off, and the boards were subjected to spray development at 20° C. for 150 seconds by using 1,1,1-trichloroethane.
After the development, the boards were heated and dried at 80° C. for 10 minutes, irradiated with ultraviolet light at 3.0 J/cm2, and then heat-treated at 130° C. for 2 hours.
The test substrates on which a protective coating film had been formed in the manner described above were subjected to an immersion test in isopropanol, toluene, trichlene or a 10% aqueous hydrochloric acid solution all at 25° C., respectively, for 10 minutes in the same manner as in Example 1-(c) to find that the formed protective coating film underwent no change.
When an immersion test was carried out in a soldering bath at 255° to 265° C. for 30 seconds, the protective coating film showed no defect and was excellent in heat resistance. Further, in the thermal shock test of 50 cycles under MIL-STD-202E method 107D condition B after the same soldering treatment as in Example 1-(c), the formed coating film did not crack.
______________________________________The urethane diacrylate com-                   60     partspound (II) obtained in Example2-a)Methyl methacrylate-meth-                   37     partsacrylic acid (98/2 weightratio) copolymer (having amolecular weight of about100,000 and a glass transitiontemperature of about 105° C.)Benzophenone            2.7    partsMichler's ketone        0.3    partp-Methoxyphenol         0.1    partVictoria pure blue      0.02   partMethyl ethyl ketone     60     partsToluene                 70     parts______________________________________
By the use of a solution of a photosensitive resin composition prepared from the above recipe, a photosensitive element in which the thickness of a layer of the photosensitive resin composition was about 80 μm was obtained by using an apparatus shown in FIG. 3, as in Example 2-(b). The photosensitive element was laminated under reduced pressure in the same manner as in Example 2-(c) on printed wiring boards for test on which a copper pattern (copper thickness: about 50 μm) shown in FIG. 1 had been formed. Further, the same treatment as in Example 2-(c) was carried out to form an imagewise protective coating film on said test substrates. The formed protective coating film showed no defect in the immersion test in isopropanol, toluene, trichlene, methyl ethyl ketone, a 10% aqueous hydrochloric acid solution or a 10% aqueous NaOH solution all at 25° C., respectively, for 10 minutes, and was so excellent in heat resistance that it did neither crack nor peel off from the substrate in the immersion test for 30 seconds in a soldering bath at 255° to 265° C. Further, when the test substrate was subjected to the same soldering treatment as in Example 1-(c) and then subjected to the thermal shock test of 50 cycles under MIL-STD-202E method 107D condition B, the protective coating film did not crack.
The same procedures as in Example 2-(b) and Example 2-(c) were carried out except that trimethylolpropane triacrylate was substituted for the urethane diacrylate compound (II) in Example 2-(b). The finally obtained protective coating film partly peeled off from the substrate in the immersion test in a soldering bath at 255° to 265° C. for 30 seconds. After the same soldering treatment as in Example 1-(c), the protective coating film cracked within 5 cycles in the thermal shock test under MIL-STD-202E method 107D condition B.
The same procedure as in Example 3 was carried out except that 20 parts of pentaerythritol triacrylate and 40 parts of a di-(3-acryloxy-2-hydroxypropyl)ester of bisphenol A were substituted for 60 parts of the urethane diacrylate compound (II) in Example 3. After the same soldering treatment as in Example 1-(c), the finally obtained protective coating film cracked within 5 cycles in the thermal shock test under MIL-STD-202E method 107D condition B. A part of the protective coating film was about to peel off from the substrate in the immersion test for 10 minutes in a 10% aqueous hydrochloric acid solution.
______________________________________Trimethylolpropane triacrylate                   30     partsPolypropylene glycol (having an                   10     partsaverage molecular weight of 1,000)diacrylateMethyl methacrylate-methacrylic                   50     partsacid-tetrahydrofurfuryl meth-acrylate (78/2/20 weight ratio)copolymer (having a molecularweight of about 150,000 and aglass transition temperature ofabout 95° C.)Benzophenone            2.7    partsMichler's ketone        0.3    partp-Methoxyphenol         0.5    partMethyl ethyl ketone     200    parts______________________________________
______________________________________The urethane diacrylate com-                   60     partspound (III) obtained in themanner described aboveMethyl methacrylate-meth-                   37     partsacrylic acid-tribromophenylacrylate (38/2/60 weight ratio)copolymer (having a molecularweight of about 120,000, aglass transition temperature ofabout 120° C. and a brominecontent of 37% by weight)Benzophenone            2.7    parts4,4'-Bis(diethylamino)- 0.3    partbenzophenone2,2'-methylenebis(4-ethyl-                   0.3    part6-t-butylphenol)Victoria pure blue      0.02   partMethyl ethyl ketone     100    partsToluene                 50     parts______________________________________
The same procedures as in Example 2-(b) and Example 2-(c) were followed, with the exception that a solution of a photosensitive resin composition prepared from the above recipe was used. The finally obtained protective coating film showed no defect in the immersion test for 10 minutes in a 10% aqueous hydrochloric acid solution, and underwent no change such as peeling-off and cracking when immersed in a soldering bath at 255° to 265° C. for 30 seconds. After the same soldering treatment as in Example 1-(c), the protective coating film did not crack in the thermal shock test of 50 cycles under MIL-STD-202E method 107D condition B. A protective coating film was formed by the same procedure as in the above on the whole surface of a substrate of 0.8 mm in thickness of a printing wiring substrate MCL-E-68 (UL flame-retardancy grade 94V-0) manufactured by Hitachi Chemical Co., Ltd. This protective coating film satisfied the standards of 94V-1 of UL.
______________________________________The urethane diacrylate com-                   50     partspound (IV) obtained in themanner described aboveMethyl methacrylate-methyl                   47     partsacrylate-acrylic acid-tetra-hydrofurfuryl methacrylate-tribromophenyl acrylate(40/23/2/10/25 weight ratio)copolymer (having a molecularweight of about 80,000, a glasstransition temperature of about75° C. and a bromine content of15% by weight)Benzophenone            2.7    partsMichler's ketone        0.3    part2,2'-Methylenebis(4-methyl-6-                   0.5    partt-butylphenol)Victoria pure blue      0.02   partMethyl ethyl ketone     100    partsToluene                 50     parts______________________________________
The same procedures as in Example 2-(b) and Example 2-(c) were followed, with the exception that a solution of a photosensitive resin composition prepared from the above recipe was used. The finally obtained protective coating film showed no defect in the immersion test for 10 minutes in isopropanol, toluene, trichlene, or a 10% aqueous hydrochloric acid solution, and underwent no change such as peeling-off and cracking when immersed in a soldering bath at 255° to 265° C. for 30 seconds. After the same soldering treatment as in Example 1-(c), the protective coating film did not crack in the thermal shock test of 50 cycles under MIL-STD-202E method 107D condition B. A protective coating film was formed by the same procedure as in the above on the whole surface of a substrate of 1.6 mm in thickness of a printed wiring board MCL-E-68 manufactured by Hitachi Chemical Co., Ltd. This protective coating film satisfied the standards of 94V-1 of UL.
The same procedure as in Example 5-(b) was followed, with the exception that 1 part of antimony trioxide was additionally incorporated into the solution of the photosensitive resin composition in Example 5-(b). The finally obtained protective coating film was as good as in Example 5-(b) in solvent resistance, heat resistance and resistance to thermal shock. A protective coating film was formed by the same procedure as in the above on the whole surface of a substrate of 1.6 mm in thickness of a printed wiring substrate MCL-E-68 manufactured by Hitachi Chemical Co., Ltd. This protective coating film satisfied the standards of 94V-0 of UL.
(a) Synthesis of a urethane dimethacrylate compound
______________________________________The urethane dimethacrylate com-                   40     partspound (V) obtained in themanner described aboveMethyl methacrylate-meth-                   57     partsacrylic acid-tetrafurfurylmethacrylate-acrylonitrile-tribromophenyl acrylate(43/2/20/5/30 weight ratio)copolymer (having a molecularweight of about 150,000, aglass transition temperatureof about 100° C. and a brominecontent of 18% by weight)Benzophenone            2.7    partsMichler's ketone        0.3    partp-Methoxyphenol         0.05   partVictoria pure blue      0.05   partToluene                 150    parts______________________________________
The same procedures as in Example 2-(b) and Example 2-(c) were followed, with the exception that a solution of a photosensitive resin composition prepared from the above recipe was used. The finally obtained protective coating film showed no defect in the immersion test for 10 minutes in isopropanol, toluene, trichlene or a 10% aqueous hydrochloric acid solution, and underwent no change such as peeling-off and cracking when immersed in a soldering bath at 255° to 265° C. for 30 seconds. After the same soldering treatment as in Example 1-(c), it did not crack in the thermal shock test of 50 cycles under MIL-STD-202E method 107D condition B. A protective coating film was formed by the same procedure as above on the whole surface of a substrate of 1.6 mm in thickness of a printed wiring substrate MCL-E-68 manufactured by Hitachi Chemical Co., Ltd. This protective coating film satisfied the standards of 94V-1 of UL.
______________________________________The urethane diacrylate com-                    47     partspound (VI) obtained in themanner described aboveMethyl methacrylate-methyl                    50     partsacrylate-acrylic acid-tetra-hydrofurfuryl methacrylate-2-hydroxyethyl methacrylate-tribromophenyl acrylate(43/10/2/5/5/35 weight ratio)copolymer (having a molecularweight of about 150,000, aglass transition temperatureof about 90° C. and a brominecontent of 22% by weight)Benzophenone             2.7    partsMichler's ketone         0.3    partp-Methoxyphenol          0.05   partVictoria pure blue       0.02   partKAYAMER PA-2 (manufactured by                    0.1    partNihon Kayaku Co., Ltd.:divalent acrylate containinga phosphoric acid group)Methyl ethyl ketone      50     partsToluene                  100    parts______________________________________
The photosensitive element obtained in the above was laminated under reduced pressure in the same manner as in Example 2-(c) on a printed wiring boards for test on which a copper pattern (copper thickness: about 18 μm) shown in FIG. 1 had been formed. After the lamination, the printed wiring boards were allowed to stand at room temperature for 3 hours, and then exposed at 200 mJ/cm2 through a negative mask for test shown in FIG. 2, as in Example 1-(c). After the exposure, the boards were heated at 80° C. for 5 minutes and then allowed to cool at room temperature for 20 minutes, after which the support film was peeled off, and the boards were subjected to spray development at 20° C. for 70 seconds by using 1,1,1-trichloroethane. After the development, the boards were heated and dried at 80° C. for 30 minutes, and further heated at 120° C. for 30 minutes and then at 150° C. for 30 minutes. The heated boards were allowed to cool at room temperature for 10 minutes, irradiated with ultraviolet light at 10 J/cm2, and then heat-treated at 130° C. for 2 hours.
The test substrates on which a protective coating film had been formed in the manner described above were subjected to the immersion test for 10 minutes in isopropanol, toluene, trichlene or a 10% aqueous hydrochloric acid solution all at 25° C. in the same manner as in Example 1-(c), to find that the protective coating film showed no defect. The protective coating film did not peel off in the immersion test for 30 minutes in a soldering bath at 255° to 265° C. and hence was good in heat resistance. After the same soldering treatment as in Example 1-(c), the film did not crack in the thermal shock test of 50 cycles under MIL-STD-202E method 107D condition B. The protective coating film was so excellent in adhesion that it did not peel off in a cross-cutting test. A protective coating film was formed by the same procedure as in the above on the whole surface of a substrate of 0.8 mm in thickness of a printed wiring substrate MCL-E-68 manufactured by Hitachi Chemical Co., Ltd. This protective coating film satisfied the standards of 94V-1 of UL.
A urethane diacrylate compound was synthesized in the same manner as in Example 1-(a), except that 1,344 parts (16 equivalents) of hexamethylene diisocyanate was substituted for 1,680 parts (16 equivalents) of trimethylhexamethylene diisocyanate in Example 1-(a).
The ingredient A was placed in a reactor having a capacity of about 5 liters equipped with a thermometer, a stirrer, a condenser, a nitrogen-gas-introducing tube and a dropper which could be heated and cooled, and than A was heated to 60° C. with stirring. B was uniformly added dropwise to A in the reactor over a period of about 3 hours while maintaining the reaction temperature at 55° to 65° C. After the addition of B, the resulting mixture was maintained at a temperature of 55° to 65° C. for about 2 hours, after which C was uniformly added thereto dropwise at a temperature of about 55° to 65° C. over a period of about 3 hours. After the addition of C, the reaction temperature was gradually raised to 80° C. over a period of about 5 hours.
Thereafter, the temperature was lowered to 60° C., after which D was added to the reaction mixture, and the thus obtained mixture was continuously stirred for about 1 hour. A solution (VIII) of a urethane diacrylate compound which contained 70% of nonvolatile matters was thus obtained.
______________________________________The solution (VIII) of a urethane                   70 partsdiacrylate compound obtained                   (49 parts inin the manner described above                   terms of non-                   volatile                   matters)Methyl methacrylate-methacrylic                   47 partsacid-tetrahydrofurfuryl methacrylate(78/2/20: weight ratio) copolymer(having a molecular weight of about150,000 and a glass transitiontemperature of about 95° C.)2-Ethylanthraquinone     4 partsp-Methoxyphenol         0.1 partCrystal violet          0.1 partMethyl ethyl ketone     80 parts______________________________________
A solution of a photosensitive resin composition was prepared according to the above recipe, applied to a polyimide film of about 50 μm in thickness, and dried at room temperature for 20 minutes, at 80° C. for 10 minutes and then at 105° C. for 5 minutes to obtain a photosensitive element in which the thickness of a layer of the photosensitive resin composition was about 60 μm.
The photosensitive element obtained in above (b) was laminated on each of the test substrates by using an A-500 type laminater manufactured by Akebono Industry Co., Ltd. After the lamination, the polyimide film as a support film was peeled off, and the test substrates were exposed at 900 mJ/cm2 by means of a Phenix 3000 type exposing machine manufactured by ORC Factory Co., Ltd. by using a negative mask for test shown in FIG. 2. In FIGS. 2, 3 shows an opaque part of the negative mask and 4 shows a transparent part of the negative mask, and the unit of the figures is mm. After the exposure, the test substrates were allowed to stand for 30 minutes, and then subjected to spray development at 20° C. for 90 seconds by using 1,1,1-trichloroethane.
After the development, the test substrates were heated and dried at 80° C. for 10 minutes, and then irradiated at 2.5 J/cm2 by using an ultraviolet light irradiating equipment manufactured by Toshiba Denzai Co., Ltd.
Thereafter, they were heat-treated at 150° C. for 30 minutes. Four of the six test substrates on which a protective coating film was thus formed were immersed in isopropanol, toluene, trichlene, or a 10% aqueous hydrochloric acid solution all at 25° C., respectively, for 10 minutes to find that the formed protective coating film underwent no change.
When another one of the test substrates was immersed in a soldering bath at 255° to 265° C. for 30 seconds, its protective coating film was so stable that it did neither crack nor peel off from the substrate, and therefore it was found to be sufficiently usable as a soldering mask.
Further, the remaining one test substrate was subjected to soldering treatment in a soldering bath at 255° to 265° C. for 3 seconds by using a rosin series flux A-226 (manufactured by Tamura Kaken Co., Ltd.), and then subjected to the thermal shock test of 20 cycles under MIL-STD-202E method 107D condition B (-65° C. for 30 minutes⃡ordinary temperature for 5 minutes or less⃡125° C. for 30 minutes). As a result, its protective coating film did not crack and was found to be greatly excellent in long-term reliability.
______________________________________The urethane diacrylate                  40     partscompound (IX) obtainedin the manner describedaboveMethyl methacrylate-methyl                  57     partsacrylate-2-hydroxyethylmethacrylate-acrylonitrile(80/10/5/5 weight ratio)copolymer (having amolecular weight of about100,000 and a glasstransition temperature ofabout 90° C.)Benzophenone           2.7    partsMichler's ketone       0.3    partp-Methoxyphenol        0.1    partVictoria pure blue     0.05   partMethyl ethyl ketone    80     partsToluene                40     parts______________________________________
A solution 10 of a photosensitive resin composition prepared from the above recipe was uniformly applied to a polyethylene terephthalate film 16 of 25 μm in thickness by using an apparatus shown in FIG. 3, and then dried in a hot-air convention dryer 11 at 80° to 100° C. for about 10 minutes. The thickness after drying of the layer of the photosensitive resin composition was about 100 μm. A polyethylene film 17 of about 25 μm in thickness was stuck, as a covering film, on the layer of the photosensitive resin composition, as shown in FIG. 3. In FIG. 3, 5 shows a polyethylene terephthalate film delivering roll, 6, 7 and 8 rolls, 9 a knife, 12 a polyethylene film delivering roll, 13 and 14 rolls and 15 a photosensitive element wiring roll.
The photosensitive element obtained in the above was laminated with heating under pressure on a printed wiring board for test (having a glass epoxy substrate and a thickness of 1.6 mm) in which a copper pattern (copper thickness: about 70 μm) shown in FIG. 1 had been formed, by using a vacuum laminater manufactured by Hitachi Chemical Industry Co., Ltd. (degree of vacuum: 30 mmHg, lamination temperature: 100° C., lamination speed: 2 m/min.). After the lamination, the printed wiring boards were heated at 60° C. for 5 minutes, allowed to stand at room temperature for 3 hours, and then exposed at 150 mJ/cm2 through a negative mask for test shown in FIG. 2, as in Example 9-(c).
The test substrates on which a protecting coating film had been formed in the manner described above were subjected to the immersion test for 10 minutes in isopropanol, toluene, trichlene, or a 10% aqueous hydrochloric acid solution all at 25° C. in the same manner as in Example 9-(c) to find that the formed protective coating film underwent no change.
When the immersion test was carried out in a soldering bath at 255° to 265° C. for 30 seconds, the protective coating film showed no defect and hence was excellent in heat resistance. After the same soldering treatment as in Example 9-(c), the formed coating film did not crack in the thermal shock test of 20 cycles under MIL-STD-202E method 107D condition B.
______________________________________The urethane diacrylate compound                    60     parts(IX) obtained in Example 10-a)Methyl methacrylate-methacrylic                    37     partsacid (98/2 weight ratio) copolymer(having a molecular weight of about100,000 and a glass transitiontemperature of about 105° C.)Benzophenone             2.7    partsMichler's ketone         0.3    partp-Methoxyphenol          0.1    partVictoria pure blue       0.02   partMethyl ethyl ketone      60     partsToluene                  70     parts______________________________________
By the use of a solution of a photosensitive resin composition prepared from the above recipe, a photosensitive element in which the thickness of a layer of the photosensitive resin composition was about 80 μm was obtained by using an apparatus shown in FIG. 3, as in Example 10-(b). The photosensitive element was laminated under reduced pressure in the same manner as in Example 10-(c) on printed wiring boards for test on which a copper pattern (copper thickness: about 50 μm) shown in FIG. 1 had been formed. Further, the same treatment as in Example 10-(c) was carried out to form an imagewise protective coating film on said test substrates. The formed protective coating film showed no defect in the immersion test for 10 minutes in isopropanol, toluene, trichlene, methyl ethyl ketone, a 10% aqueous hydrochloric acid solution or a 10% aqueous NaOH solution all at 25° C., and was so excellent in heat resistance that it did neither crack nor peel off from the substrate in the immersion test for 30 seconds in a soldering bath at 255° to 265° C. after the same soldering treatment as in Example 9-(c). After the same soldering treatment as in Example 9-(c), the protective coating film did not crack in the thermal shock test of 20 cycles under MIL-STD-202E method 107D condition B.
The same procedures as in Example 10-(b) and Example 10-(c) were followed, with the exception that trimethylolpropane triacrylate was substituted for the urethane diacrylate compound (IX) in Example 10-(b). The finally obtained protective coating film partly peeled off from the substrate in the immersion test for 30 seconds in a soldering bath at 255° to 265° C. After the same soldering treatment as in Example 9-(c), the protective coating film cracked within 5 cycles in the thermal shock test under MIL-STD-202E method 107D condition B.
The same procedure as in Example 11 was followed, with the exception that 20 parts of pentaerythritol triacrylate and 40 parts of di-(3-acryloxy-2-hydroxypropyl) ester of bisphenol A were substituted for 60 parts of the urethane diacrylate compound (IX) in Example 11. The finally obtained protective coating film cracked in the thermal shock test of 5 cycles under MIL-STD-202E method 107D condition B after the same soldering treatment as in Example 9-(c). A part of the protective coating film was about to peel off from the substrate in the immersion test for 10 minutes in a 10% aqueous hydrochloric acid solution.
______________________________________Trimethylolpropane triacrylate                    30     partsPolypropylene glycol (having an                    10     partsaverage molecular weight of 1,000)diacrylateMethyl methacrylate-methacrylic acid-                    50     partstetrahydrofurfuryl methacrylate(78/2/20 weight ratio) copolymer(having a molecular weight of about150,000 and a glass transitiontemperature of about 95° C.)Benzophenone             2.7    partsMichler's ketone         0.3    partp-Methoxyphenol          0.5    partMethyl ethyl ketone      200    parts______________________________________
______________________________________The urethane diacrylate compound (X)                    60     partsobtained in the manner described aboveMethyl methacrylate-methacrylic acid-                    37     partstribromophenyl acrylate (38/2/60weight ratio) copolymer (having amolecular weight of about 120,000,a glass transition temperature ofabout 120° C. and a bromine contentof 37% by weight)Benzophenone             2.7    parts4,4'-Bis(diethylamino)benzophenone                    0.3    part2,2'-Methylenebis(4-ethyl-6-t-                    0.3    partbutylphenol)Victoria pure blue       0.02   partMethyl ethyl ketone      100    partsToluene                  50     parts______________________________________
The same procedures as in Example 10-(b) and Example 10-(c) were followed, with the exception that a solution of a photosensitive resin composition prepared from the above recipe was used. The finally obtained protective coating film showed no defect in the immersion test for 10 minutes in isopropanol, toluene, trichlene or a 10% aqueous hydrochloric acid solution all at 25° C., and underwent no change such as peeling-off and cracking when immersed in a soldering bath at 255° to 265° C. for 30 seconds. It did not crack also in the thermal shock test of 20 cycles under MIL-STD-202E method 107D condition B after the same soldering treatment as in Example 9-(c). A protective coating film was formed of the same procedure as in the above on the whole surface of a substrate of 0.8 mm in thickness of a printed wiring substrate MCL-E-68 (UL flame-retardancy grade 94V-0) manufactured by Hitachi Chemical Co., Ltd. This coating film satisfied the standards of 94V-1 of UL.
______________________________________The urethane diacrylate compound (XI)                    50     partsobtained in the manner describedaboveMethyl methacrylate-methyl acrylate-                    47     partsacrylic acid-tetrahydrofurfurylmethacrylate-tribromophenylacrylate (40/23/2/10/25 weight ratio)copolymer (having a molecularweight of about 80,000, a glasstransition temperature of about75° C. and a bromine content of 15%)Benzophenone             2.7    partsMichler's ketone         0.3    part2,2'-Methylenebis(4-methyl-6-t-                    0.5    partbutylphenol)Victoria pure blue       0.02   partMethyl ethyl ketone      100    partsToluene                  50     parts______________________________________
The same procedures as in Example 10-(b) and Example 10-(c) were followed, with the exception that a solution of a photosensitive resin composition prepared from the above recipe was used. The finally obtained protective coating film showed no defect in the immersion test for 10 minutes in isopropanol, toluene, trichlene or a 10% aqueous hydrochloric acid solution all at 25° C., and underwent no change such as peeling-off and cracking when immersed in a soldering bath at 255° to 265° C. for 30 seconds. It did not crack also in the thermal shock test of 20 cycles under MIL-STD-202E method 107D condition B after the same soldering treatment as in Example 9-(c). A protective coating film was formed by the same procedure as in the above on the whole surface of a substrate of 1.6 mm in thickness of a printed wiring substrate MCL-E-68 manufactured by Hitachi Chemical Co., Ltd. This coating film satisfied the standards of 94V-1 of UL.
The same procedure as in Example 13 was followed, with the exception that 1 part of antimony trioxide was additionally incorporated into the solution of a photosensitive resin composition in Example 13-(b). The finally obtained protective coating film was as good as in Example 13-(b) in solvent resistance, heat resistance and resistance to thermal shock. A protective coating film was formed by the same procedure as in the above on the whole surface of a substrate of 1.6 mm in thickness of a printed wiring substrate MCL-E-68 manufactured by Hitachi Chemical Co., Ltd. This coating film satisfied the standards of 94V-0 of UL.
______________________________________The urethane dimethacrylate compound                    40     parts(XII) obtained in the mannerdescribed aboveMethyl methacrylate-methacrylic acid-                    57     partstetrahydrofurfuryl methacrylate-acrylonitrile-tribromophenyl acrylate(43/2/20/5/30 weight ratio) copolymer(having a molecular weight of 150,000,a glass transition temperature ofabout 100° C. and a bromine content of18% by weight)Benzophenone             2.7    partsMichler's ketone         0.3    partp-Methoxyphenol          0.05   partVictoria pure blue       0.05   partToluene                  150    parts______________________________________
The same procedures as in Example 10-(b) and Example 10-(c) were followed, with the exception that a solution of a photosensitive resin composition prepared from the above recipe was used. The finally obtained protective coating film showed no defect in the immersion test for 10 minutes in isopropanol, toluene, trichlene or a 10% aqueous hydrochloric acid solution all at 25° C., and underwent no change such as peeling off and cracking when immersed in a soldering bath at 255° to 265° C. for 30 seconds. Further, it did not crack also in the thermal shock test of 20 cycles under MIL-STD-202E method 107D condition B after the same soldering treatment as in Example 9-(c). A protective coating film was formed by the same procedure as in the above on the whole surface of a substrate of 1.6 mm in thickness of a printed wiring substrate MCL-E-68 manufactured by Hitachi Chemical Co., Ltd. This coating film satisfied the standards of 94V-1 of UL.
______________________________________The urethane diacrylate compound                    47     parts(XIII) obtained in the mannerdescribed aboveMethyl methacrylate-methyl acrylate-                    50     partsacrylic acid-tetrahydrofurfurylmethacrylate-2-hydroxyethylmethacrylate-tribromophenylacrylate (43/10/2/5/5/35 weightratio) copolymer (having amolecular weight of about 150,000,a glass transition temperature ofabout 90° C. and a bromine contentof 22% by weight)Benzophenone             2.7    partsMichler's ketone         0.3    partp-Methoxyphenol          0.05   partVictoria pure blue       0.02   partKAYAMER PA-2 (manufactured by                    0.1    partNihon Kayaku Co., Ltd., adivalent acrylate containing aphosphoric acid group)Methyl ethyl ketone      50     partsToluene                  100    parts______________________________________
The photosensitive element obtained in the above was laminated, under reduced pressure in the same manner as in Example 10-(c), on a printed wiring board for test on which a copper pattern (copper thickness: about 18 μm) shown in FIG. 1 had been formed. After the lamination, and printed wiring boards were allowed to stand at room temperature for 3 hours, and then exposed, as in Example 9-(c), at 200 mJ/cm2 through a negative mask for test shown in FIG. 2. After the exposure, the boards were heated at 80° C. for 5 minutes and then allowed to cool at room temperature for 20 minutes, after which the support film was peeled off, and the boards were subjected to spray development at 20° C. for 70 seconds by using 1,1,1-trichloroethane. After the development, the boards were heated and dried at 80° C. for 30 minutes, and further heated at 120° C. for 30 minutes and then at 150° C. for 30 minutes. The heated boards were allowed to cool at room temperature for 10 minutes, irradiated with ultraviolet light at 10 J/cm2, and then heat-treated at 130° C. for 2 hours. The test substrates on which a protective coating film was thus formed were subjected to the immersion test for 10 minutes in isopropanol, toluene, trichlene or a 10% aqueous hydrochloric acid solution all at 25° C. in the same manner as in Example 9-(c) to find that the protective coating film showed no defect. The protective coating film did not peel off in the immersion test for 30 seconds in a soldering bath at 255° to 265° C., and hence was good in heat resistance. Further, it did not crack in the thermal shock test of 20 cycles under MIL-STD-202E method 107D condition B after the same soldering treatment as in Example 9-(c). The protective coating film did not peel off in the cross-cutting test, and hence is excellent in adhesion. A protective coating film was formed by the same procedure as in the above on the whole surface of a substrate of 0.8 mm in thickness of a printed wiring substrate MCL-E-68 manufactured by Hitachi Chemical Co., Ltd. This coating film satisfied the standards of 94V-1 of UL.
A urethane diacrylate compound was synthesized in the same manner as in Example 9-(a), except that 1,344 parts (16 equivalents) of hexamethylene diisocyanate was substituted for 1,776 parts (16 equivalents) of the isophorone diisocyanate. The produced urethane diacrylate compound (XIV) was insoluble in toluene, the reaction solvent, and separated as wax just as it was produced. The obtained urethane diacrylate compound (XIV) was slightly soluble in methyl ethyl ketone and 1,1,1-trichloroethane, and soluble in acetone and chloroform.
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U.S. Classification 430/5, 522/95, 430/325, 430/531, 430/396, 522/92, 430/284.1, 430/330
International Classification G03F7/027, C08F2/50, C08F299/06, C08G18/67, G03F7/004
Cooperative Classification C08F2/50, C08G18/672, G03F7/027, C08F299/065
European Classification C08F299/06B, C08G18/67B4, G03F7/027, C08F2/50