LU81652A1 - COMPOSITION FOR POSITIVE PHOTORESERVES - Google Patents

Description

8- λ L-2431

Ά C Pî GRAND-DUCHY OF LUXEMBOURG

.........! ...... M.

from 05 .. 09 * .19 7.9 .............. Minister "Title issued - from the National Economy and the Middle Classes _______ Industrial Property Service

LUXEMBOURG

Patent Application I. Application

Minnesota Mining and Manufacturing Company, 3M Center, .......... j ^ n “™ s ^ ~ T5T01 ~ ..... εΓΘΤα77 ...... rëprës'enteë '' 'paf .. ........................................

Jean Waxweiler, 21-25 AlléeScheffer / Luxembourg, acting as agent files this September 5, nineteen hundred and seventy-nine ^ at ....... hours, at the Ministry of National Economy and the Middle Classes, at Luxembourg: 1. the present request for obtaining a patent for an invention concerning: .............................. .................................................. .................................................. ......................................... * ........ ......................................__........... .......................................... (41

Composition for positive photoreserve.

declares, assuming responsibility for this declaration, that the inventor (s) is (are): .... J.ohn ..,. B, .. V.ike.sl.an.d. .... and .... Richard .... M..P_re.sley .............................. .................................................. .......................... (5) 3M Center, Saint Paul, Minnesota 55101, USA

2. the delegation of power, dated_____________________________________________________________________ on ____________________________________________________________________ 3. the description in French ...................... ---------- ------------ <I invention in two copies; 4 ....... / .._____________________ drawing boards, in two copies; 5. the receipt of the fees paid to the Registration Office in Luxembourg, the five th September one thousand nine hundred and seventy-nine claims for the above patent application the priority of one (s) request (s) from (6) - ----------------- ferevet -------------------------------- ----------------- filed in (7) .............._______________________, _________________________........ .....................

six september one thousand nine hundred and seventy-eight under no.

, the 9jgv9Bg · ---------------------------------------------- ---------------------------------------------------------- ---------------------------------------------------------- ---------------------------------------------------------- - (8)

John P. Vikesïand and Richard M. Presïéÿ on behalf of ...................................... .................................................. .................................................. .................................................. .................................................. ..... (9) elect domicile for him (her) and, if designated, for his representative, in Luxembourg ________________________ _________ Jean-JWaxMeil.er ^ .21-25 ···· Allée Schefier.f.Lmgembourq __________________________________________________ ao) request the issuance of a patent for the subject described and represented in the abovementioned appendices, - with postponement of this grant to ........... 6______________________________months.

The i | andatai ^ e ^ _______________________ ^ Π. Procès-verbal de Dépôt • The above application for a patent for invention has been filed with the Ministry of National Economy and the Middle Classes, Industrial Property Service in Luxembourg, on: 05.09.1979 15.00 ..... .... Pr. the Minister, at ................................ hours \ \ of the National Economy and the Middle Classes,

GoiC \ J

ίΙ, 'Λ F tn_ ~ _

CLAIM OF PRIORITY

Filing of demandeο patent application in u.a.

September 6, 1978 Sôus * number 939.989

DESCRIPTIVE MEMORY FILED IN SUPPORT OF A PATENT INVENTION APPLICATION IN THE GRAND DUCHY OF LUXEMBOURG

*

MINNESOTA MINING AND MANUFACTURING COMPANY

by; COMPOSITION FOR POSITIVE PHOTORESERVES.

for r:>> 4

The present invention relates to a composition for positive photoresist.

In the manufacture of dry photosensitive elements, such as lithographic plates, photoresists and the like, photosensitive compositions are used which are negative or positive. Negative systems become insoluble in the form of an image after exposure to actinic radiation. As the exposed areas are made relatively insoluble, particular developing solutions can dissolve or otherwise remove the unexposed portions of the composition while leaving the exposed areas intact. So the contrast of the image obtained is the opposite of the contrast of the original and it therefore constitutes a negative image. Conversely, with positive systems, the exposed portions are made more soluble or made developable by exposure to actinic radiation and can thus be eliminated with particular developing solutions while the unexposed portions remain intact. In this case, an image 20 is obtained whose contrast corresponds to that of the original image, that is to say a positive image.

In the particular field of photoresist manufacturing, a photoresist is typically used to form an image on a substrate so as to image protect the substrate material in subsequent chemical or physical manufacturing operations such as chemical bite, vacuum metallization or the formation of an electrolytic deposit. In other words, after exposure and development of the material constituting the photoresist, the underlying substrate carrying the photoresist can be subjected to a physical treatment producing a modification corresponding to the image, that is to say n affecting only areas that are not protected by the reserve. In the manufacture of copper coated circuit boards, a photoresist is typically applied to the surface of the circuit board and then an image is developed which is developed. After this initial treatment, an etching solution is sprayed from top to bottom under high pressure onto the “2 f substrate, to remove the metallic copper which is not protected by the photoresist and to obtain a metallic circuit similar to the image after elimination of the photoresist.

To accurately reproduce the structure of the fired cir-5, it is necessary that the photoresist strongly adheres to the substrate to which it is applied and has great cohesion. Adhesion is necessary so that the etching solution does not excessively dig under the reserve thereby reducing the resolution of the image, and cohesion is necessary to maintain the proper structure of the circuit. The dry resist films must have reasonable flexibility, be able to be applied under heat and under pressure, be able to be exposed with a reasonable speed, have excellent development characteristics with sprays at moderate pressure of developing solutions, form coatings. of excellent quality (that is to say free of physical defects), being able to be rapidly eliminated by chemical means after use and producing a visible image after exposure to actinic radiation.

20 Negative dry reserve films have been known for a long time. An important feature that a reserve must have is resolution. The resolution of positive reserves is inherently superior to that of their negative equivalents. This difference is due in part to the generally necessary presence of an oxygen impermeable barrier film before and during the exposure of the negative stock, since conventional negative materials are generally sensitive to oxygen.

Some characteristic conditions relating to resolution in the electronics industry are as follows: the production of general purpose printed circuits typically requires lines of 0.25 mm with spaces of 0.25 mm, that of printed circuits precision, lines of 0.025 mm with spaces of 0.025 mm and micro-electronics néces-35 site of lines and spaces less than 2.5 µm.

To date, the dry reserve film market consists almost exclusively of negative reserves. This is essentially due to the fact that a positive photoresist film has not yet been developed satisfying the aforementioned criteria. Positive resist films typically exhibit excessive brittleness leading to spalling of the resist upon even moderate bending of the backing sheet, coating defects, insufficient cohesion causing breakage upon chemical bite and poor adhesion of the photoresist to the surface of the substrate.

The invention relates to a novel positive photo-sensitive composition useful for preparing dry photoresist films which satisfy many of the above criteria. In addition, the photoresist composition of the invention, in the cured state, is oleophilic, i.e., takes up ink and can therefore be used as a coating on aluminum or steel surfaces stainless to form lithographic printing plates or to make bimetallic printing plates.

The invention relates to a positive photosensitive composition particularly useful for forming photoresists which comprises: (a) a crosslinked urethane resin formed by catalyzed crosslinking of a non-heat reactive novola-type phenolic resin and a di-isocyanate compound; (b) an epoxy resin having an epoxy equivalent weight of less than about 400 and a curing agent for this resin; and (c) a positive photosensitizer.

In the preferred application of the composition to a substrate (which may be a temporary support layer, a separable film or a substrate which is coated with the composition before treatment) and drying, the epoxy resin hardens and dry film obtained constitutes an ideal photoresist dry film. In addition, the dry film is oleophilic and can therefore be used as the surface of a printing plate.

In the form of a dry coating, the positive composition of the invention basically consists of two networks of mixed and interlaced polymer resins. The first of these networks consists of a crosslinked urethane resin formed by crosslinking a diisocyanate with a phenolic ¥ 4 resin of the novolak type and the second consists of a hot-curing epoxy resin. The resin mixture contains a positive photosensitizer which provides photosensitivity to the system.

The urethane resin is formed in solution by the catalyzed crosslinking reaction of a novolak type phenolic resin and a polyisocyanate which is preferably a tri or a diisocyanate and better still a long chain diisocyanate.

The components used to form the urethane can simply be dissolved in a suitable solvent with a suitable catalyst for the crosslinking reaction to take place. When the viscosity of the solution stabilizes, the reaction is complete.

The novolak type phenolic resin should typically constitute from about 40 to about 80 and preferably 50 to 70% by weight of the composition and should not react to heat. By this is meant in the invention that the resin should practically not polymerize by simple heating.

A significant polymerization corresponds to an increase in the average molecular weight of at least 10%. Preferably, the average molecular weight must, by heating, have a zero increase or at most 4%. Increasing the concentration of novolak can increase the brittleness of the film and undesirably increase the solubility of unexposed areas of the film, which can cause an insufficient difference in solubility between the exposed and unexposed areas of the film. film. The decrease in concentration can prevent proper development of the film after image exposure with actinic radiation. The preferred novolac type resins are formaldehyde phenolic novolaks having a molecular weight of about 500 to 1,000. Among these resins are those of US Patent No. 4,148,655 which are prepared from different phenolic components.

The polyisocyanates useful in the invention are the conventional aromatic and aliphatic polyisocyanates. Preferably, the polyisocyanates are long chain, which means that the isocyanate radicals are joined by bonds having about 10 to about 40 or 50 carbon atoms. Aromatic and aliphatic diisocyanates with a shorter chain (for example of 6 carbon atoms) or longer remain useful in the practice of the invention.

For example, diisocyanatoisophorone, diisocyanatoto-luene and any other diisocvanate are particularly useful. The polyisocyanate should preferably be present at a concentration of from about 6 to about 12 parts by weight per 100 parts by weight of the novolak type resin, depending on the molecular weight or the isocyanate equivalent of the polyisocyanate. In general, the weight percentage should not go outside a range of around 3 to 20% relative to the weight of the novolak type resin. Higher amounts tend to make the produced film extremely brittle, with insufficient cohesion, and in the case of photoresists, adhesion to the substrate to which the film is applied is reduced. Smaller amounts tend to cause poor film plating and poor removal of exposed areas during development. Any catalyst which is known to be useful for catalyzing the formation of urethanes can be used. The catalysts which are particularly preferred are tertiary amines such as, for example, 1,4-diaza-bicyclo [2.2.2] octane and tris (dimethylaminomethyl) -2,4,6 phenol.

The concentration of the catalyst has no particular limitation as long as an amount sufficient to cause crosslinking is present. Typically, a concentration greater than about 0.05 parts by weight per 100 parts of novolak type resin is more than sufficient to ensure complete crosslinking, and a concentration as low as 0.01 parts may be sufficient.

When the urethane formation is complete, a polymerizable epoxy resin having a weight epoxy equivalent of less than about 400 and a curing agent for that resin is added to the solution. A typical and preferred example of an epoxy resin is the diglycidyl ether of bisphenol A. The epoxy resin concentrations should be between about 20 and about 40 parts by weight per 100 6 parts by weight of the novolak type resin. An increase in concentrations tends to increase, the flexibility of the dry photosensitive film obtained but the capacity of exposure according to an image and of development is reduced. The decrease in concentration tends to reduce the adhesion and handling characteristics of the dry film obtained.

Examples of curing agents for epoxy resins include aliphatic or aromatic amines, aliphatic or aromatic anhydrides, disulfones, nitriles and other known agents. Any of these or other agents can be used in the practice of the invention. The preferred curing agents are phthalic anhydride, diaminodiphenylsulfone or a combination thereof. Typically, about 5 to about 50 parts of curing agent per 100 parts of epoxy resin is sufficient to cure the resin.

Without incorporation of the curing agent of the epoxy resin or without curing of this resin, the film obtained tends to be brittle and does not have the cohesion necessary for the performance of the photoresist to be satisfactory. On the contrary, when the epoxy resin is suitably cured, the film obtained has very increased flexibility and cohesion which makes it extremely useful as a photoresist.

The positive photosensitizer is suitably added by intimate mixing to the solution containing the urethane, the polymerizable epoxy resin and the curing agent for the epoxy resin. As examples of photosensitizers, mention may be made of diazo-oxides known in the art such as the p-30 methylphenyl ester of naphthoquinone-i, 2-diazide- (2) -5- sulfonic acid as described in the patents of the United States of America No. 3.046.120, No. 3.046.121 and NO. 3,211,553 and di-azosulfones known in the art, as described, for example, in U.S. Patents No. 2,465,760, No. 3,113,865 and No. 3,661,573 and the British patent number 1.277.428. The photosensitizers must be soluble in the solvent used to apply the coating solution.

A particularly useful photosensitizer is a naphtho-quinone- (1,2) -diazide-sulfonic- (5) -naphtho-diester sold under the name "Diazo LL" by Molecular Rearrangement Company. The positive photosensitizers of U.S. Patent No. 4,148,654 are also useful in the invention. According to the invention, a positive photosensitizer is a material which, when struck by radiation, preferably actinic radiation, decomposes into a material which is more acidic than the photosensitizer. Preferably, the photosensitizer is originally neutral or basic so that the change in pH is maximum. The photosensitizer component need not have any cohesion as it is distributed in the mixture of urethane, polymerizable epoxy resin and the curing agent.

The concentration of the photosensitizer can be between about 10 parts by weight per 100 parts of novolak type resin and the saturation of the solution.

The solvents used to form the photosensitive solution can be freely chosen and they can for example consist of methyl isobutyl ketone, methyl ethyl ketone, etc.

In practice, it is simply possible, in a known manner, to coat a support material with the solution and then dry at a temperature sufficient to harden the epoxy resin. In the case of a photoresist applied by means of a transfer film, the support film must contain a separating agent such as methylcellulose, polyvinylpyrrolidone and copolymers of methyl vinyl ether and maleic anhydride to allow easy separation of the support film, which is for example polyester, from the photoresist layer. After drying, the photo-resist composition can simply be plated with various heat using pressure and heat such as metals such as copper, stainless steel and gold, ceramics, glass, silicon dioxide and organic polymers such as polyimide, epoxy resin, polysiloxanes and polyesters.

In addition, stainless steel can be coated with the liquid photosensitive solution to prepare bimetallic printing plates by electroplating after having impressed and developed the photosensitive material or apply the liquid photosensitive solution to aluminum or aluminum. silicate to prepare printing plates, because the dry composition is by nature oleophilic.

Prior to application to a support, materials such as an alkoxysilane having epoxy or amine functions may be added to the solution to improve adhesion to substrates having surfaces of glass, silicon dioxide or the like. Examples of these materials that may be mentioned include γ-aminopropyltriethoxysilane and γ-glycidoxypropyltrimethoxy-10 silane.

The exposure can be carried out according to conventional techniques, for example with a charcoal arc, etc., according to the radiation to which the photosensitizer is sensitive. Image development is carried out with developers such as weakly alkaline solutions, etc. usually used with the sensitizers used.

The invention will be better understood on reading the detailed description which follows of a few examples which illustrate, without implied limitation, embodiments of the invention and where the parts are expressed by weight, unless otherwise indicated.

EXAMPLE 1

To prepare a positive composition, the following components are mixed at room temperature.

25

Components ...........% by weight Methyl ethyl ketone 27.6

Resinox, trade name of a phenolformaldehyde resin sold by 11.0

Monsanto Company

Tris (dimethylaminomethyl) -2,4,6 phenol 0,23 DDI-1410, trade name of an aliphatic diiso-cyanate of which the group of bridging contains about 36 atoms of 2 ^ qq carbon, marketed by General '

Mills Chemicals, Inc.

9

The solution containing the above components is mixed until its viscosity, measured with an ordinary Brookfield viscometer fitted with a No. 2 rod, stabilizes at approximately 17 centipoise and then the following components are added.

Constituents% by weight Methyl ethyl ketone 11.0 DER 331, trade name of a diglycidyl ether of bisphenol A having an epoxide equivalent by weight of 186 3.31 to 192, marketed by Dow Chemical

Company. Phthalic anhydride 0.26 15

Diaminodiphenylsulfone 0.13 1,2-naphthoquinone-diazide-5-sulfonate 3, p-tert-butylphenyl '20 After mixing thoroughly, apply the solution with a doctor blade on a thick polyester sheet of 50 μπι ο that l 'was previously coated with 5.4 mg / dm of methylcellulose, then the photosensitive coating was dried at 82 ° C for 4 minutes. The epoxy resin hardens during drying.

The film obtained is flexible enough to resist moderate bending on the support without breaking. The film is plated to a copper foil with a roller laminator heated to 100 ° C. The polyester support is removed from the photoresist after plating and the reserve is exposed to tra-30 to an original by means of a carbon arc for 50 seconds. The exposed reserve is then developed by spraying with a 1% aqueous solution of sodium hydroxide for 2 minutes. The exposed copper can then be subjected to chemical attack or electroplating by conventional industry technique.

EXAMPLE 2

To prepare a positive composition, the following components are mixed.

\ 10

Constituents% by weight Methyl ethyl ketone 27.7 5 Resinox 11.0

Diaza-1,4 bicyclo [2.2.2] octane 0.01 DDI-1410 1.23 10 until the viscosity of the solution stabilizes in the vicinity of 50 centipoises.

When the formation of urethane is complete, the following components are added to the solution.

Constituents.% By weight DER 331 3.0

Phthalic anhydride 0.3 „1,2-naphthoquinone-diazide-5-sulfonate„ _ p-tert-butylphenyl '

After coating, exposure and development as in Example 1, the film has excellent flexibility and excellent properties as a photoresist.

EXAMPLE 3

To prepare a positive composition, the following components are mixed.

30

Constituents. % by weight Methyl ethyl ketone 27.7

Resinox 11.0

Diaza-1,4 bicyclo [2.2.2] octane 0.06 DDI-1410 1.18 jo ___________ until the viscosity of the solution stabilizes.

i 11 t

The following components are then added to the solution.

Constituents% by weight 5 -: ---- DER 331 2.15

Diaminodiphenylsulfone 0.40 1,2-naphthoquinone-diazide-5-sulfonate _ _ of p-tert-butylphenyl '10 __.

After coating, drying, exposure and development as in Example 1, the film has good flexibility and good properties as a photoresist.

15 EXAMPLE 4

To prepare a photosensitive composition, the following constituents are mixed.

Constituents% by weight 2o--

Reaction product of "Resinox" and DDI-1410 of Example 1 DER 331 9

Diaminodiphenylsulfone 1.7 25 "Diazo LL", trade name of a naphtho-quinone (l, 2) -diazide- (l) -sulfonique- χ g (5) -naphthodiester marketed by '

Molecular Rearrangement, Inc.

γ-aminopropyltriethoxysilane 0.26 30 -

The solution is coated with silicate aluminum and dried at 82 ° C. The composition obtained is used as a printing plate, that is to say that it is exposed to acinic radiation to form an image, it is developed and inked. It is found that the film takes up ink and is suitable as a printing plate.

EXAMPLE 5

The present example shows that it is desirable to cure the epoxy resin in the presence of the polyurethane to form a network of two intermingled polymers.

To prepare a positive composition, the following components are mixed at room temperature.

5

Components% by weight

Acetone 27.6

Resinox, trade name of an 11 0 10 phenol-formaldehyde resin from Monsanto Company '

Tris (dimethylaminomethyl) -2.4.6 phenol 0.23 DDI-1410, trade name of an aliphatic diisocyanate from General Mills 1.00

Chemicals, Inc.

l5 -: ---

The solution containing the above components is mixed until its viscosity, measured with an ordinary Brookfield viscometer, stabilizes at approximately 15 centi-poises. This solution is combined with another which has been prepared from the following components.

Components% by weight

Acetone 11.0 25

Epon 828, trade name of a diglycidyl ether of bisphenol A having ^. an epoxy weight equivalent of 186 to 192 from Shell Chemical Company

Phthalic anhydride 0.26 30 Diaminodiphenylsulfone 0.13

The components of this second solution are brought to boiling under reflux for 20 hours. To the combined solutions, add: 35 __

Constituent% by weight 1,2-naphthoquinone-diazide-5-sulfonate 3 of p-tert-butylphenyl ...... ^, b 13

After careful mixing, the combined solution is applied with a doctor blade onto a 50 µm thick polyester sheet which has been previously coated with 5.4 mg / dm2 of methylcellulose or 5.4 mg / dm d hydrolyzed copolymer of methyl vinyl ether and maleic anhydride. The photosensitive coating is dried at 82 ° C for 4 minutes.

The film is plated on a copper foil with a cylinder laminator heated to 100 ° C. The polyester support is removed from the photoresist after plating and the resist is exposed to ultraviolet light through a photographic cover. The exposed portion of the reserve is developed by spraying with a 1% aqueous solution of sodium hydroxide.

The reserves thus obtained are lower than those 15 obtained in Examples 1 to 4. It is difficult to separate the polyester support. The quality of the image is less good and a certain degree of smearing of materials is observed from the unexposed reserve image. Also the resist is more fragile than the coatings described in Examples 1 to 4. These coatings, however, remain as good as many others used in the industry.

Of course, the invention is in no way limited to the examples described, it is capable of numerous variants accessible to those skilled in the art, depending on the applications envi-25 sctgëes and without departing from it from the spirit of invention.

Claims (18)

1. Positive photosensitive composition, characterized in that it comprises: (a) a crosslinked urethane resin formed by catalyzed crosslinking of a phenol resin of the novolak type 5 not reacting with heat and of a compound of the polyisocyanate type , (b) an epoxy resin having an epoxy equivalent weight of less than about 400 and a curing agent for said resin, and (c) a positive photosensitizer. 2. Composition according to claim 1, characterized in that the novolak type resin constitutes approximately 40 to approximately 80% of the weight of the composition, the polyisocyanate concentration is between approximately 6 and approximately 12 parts by weight per 100 parts of the novolak type resin, the concentration of the epoxy resin is between about 20 and about 40 parts by weight per 100 parts of the novolak type resin and the concentration of the photosensitizer is at least about 10 parts by weight per 100 parts novolak type resin. 3. Composition according to claim 2, characterized in that the novolak type resin constitutes approximately 50 I 70% of the weight of the composition. 4. Composition according to claim 1, characterized in that the novolak type resin is a phenol-formaldehyde compound resin of the novolak type. 5. Composition according to claim 4, characterized * in that the novolak type resin has a molecular weight of approximately 500 to approximately 1,000. 6. Composition according to claim 1, characterized in that the epoxy resin is a diglycicyl ether of bis-phenol A. 7. Composition according to Claim 1, characterized in that a curing agent is chosen from phthalic anhydride, a diaminodiphenylsulfone and their mixtures. 8. Positive photosensitive article, characterized in that it comprises a substrate whose surface is coated with a photosensitive composition comprising (a) a urethane resin formed by catalyzed crosslinking of a phenolic resin. of non-heat reacting novolak type and of a polyisocyanate type compound, (b) a cured epoxy resin, this epoxy resin having an epoxy equivalent weight of less than about 400, and (c) a positive photo-stabilizer . 9. Article according to claim 8, characterized in that the novolak type resin constitutes approximately 40 to approximately 10 80% of the weight of the composition, the polyisocyanate concentration is between approximately 6 and approximately 12 parts by weight per 100 parts of the novolak type resin, the concentration of the epoxy resin is between about 20 and about 40 parts by weight per 100 parts of the novolak type resine and the concentration of the photosensitizer is at least about 10 parts by weight per 100 parts of the novolak type resin. 10. Article according to claim 9, characterized in that the novolak type resin constitutes approximately 50 to 70% of the weight of the composition. 11. Article according to claim 8, characterized in that the novolak type resin is a resin of phenolic-formaldehyde compound novolak type. 12. Article according to claim 8, characterized in 25 cc that the novolak type resin has a molecular weight of about 500 to about 1,000. 13. Article according to claim 8, characterized in that the epoxy resin is a diglycidyl ether of bis-phenol A. 14. Article according to claim 8, characterized in that the substrate is polyester. 15. Article according to claim 8, characterized in that the substrate is aluminum. 16. Article according to claim 8, characterized in that the substrate consists of a flexible support carrying "16" a separating coating. * 17. Article according to claim B, characterized in that the substrate is made of stainless steel. 18. Article according to claim 8, characterized in that the polyisocyanate comprises a diisocyanate comprising 10 to 50 carbon atoms. o 1