JPH05188593A - Inproved composition for photoimaging - Google Patents

Abstract

PURPOSE: To provide an improved cationic polymerizable epoxy-base coating material capable of photoimaging. CONSTITUTION: This improved compsn. contains an epoxy resin system consisting essentially of about 10-80wt.% polyol resin as a condensation product of epichlorohydrin and bisphenol A and about 20-90wt.% epoxidized octafunctional bisphenol A-formaldehyde novolak resin or further contg. about 35-50wt.% epoxidized glycidyl ether of tetrabromobisphenol A if flame resistance is required and contains a cationic photoinitiator capable of initiating the polymn. of the epoxy resin system at the time of exposure with chemical radiation by about 0.1-15 pts.wt. per 100 pts.wt. of the resins. The epoxy resin system has light absorption of <0.1 in the region of 330-700nm in the case of 2.0mil (0.05mm) thickness of a film and contains an effective amt. of silica as a thixotropic agent.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates generally to photoimageable compositions, and more particularly to cationically polymerizable epoxy resin systems having a photoinitiator and optionally a sensitizer. It has improved rheological properties and improved photoimaging properties.

[0002]

BACKGROUND OF THE INVENTION There are many different examples of photoimageable compositions being utilized in various industrial processes. In one particular method, the photoimageable composition has been utilized by applying the composition to the underlying printed circuit board as a solder mask.
Photolithography technology is used to expose various base structures on the circuit board while masking parts other than the base structure so that solder can be applied to exposed structures by various soldering methods. To be done.
During the soldering process, solder adheres to this exposed underlying structure and is prevented from adhering where the residual material acts as a solder mask.

Materials for solder masks must be formulated so that they can be applied by any suitable method, such as curtain coating, and certain rheological properties are required for effective coating. It is required. In addition, the solder mask must have the property of providing efficient transmission of light or other radiation so that the photoinitiator can photolyze through any thickness of the material being coated. And, of course, when the material is used as a solder mask, this solder mask maintains the coating on the part of the board being masked, and it has a suitable physical resistance to withstand the application of the solder material without significant deterioration or alteration. And must have chemical properties. Other properties may be needed if used for different purposes.

There are numerous prior art proposals for various photoimageable compositions, including many that utilize epoxies. Examples of these can be found in the following US patents: 4,279,985; 4,548,890;
4,351,708; 4,138,255; 4,069,
055; 4,250,053; 4,058,401;
4,659,649; 4,544,623; 4,684,
671; 4,624,912; 4,175,963;
4,081,276; 4,693,961; and 4,
442,197, etc. Each of these patents describes various resins and photoinitiators for use in photoimageable compositions, many of which are useful as solder masks. However, none teaches or implies a particular composition of the invention.

[0005]

SUMMARY OF THE INVENTION In accordance with the present invention, improved photoimageable, cationically polymerizable, epoxy-based coating materials are provided. This material is a condensation product of epichlorohydrin and bisphenol A, about 10 to 80 weight percent of a high molecular weight polyol resin such as a polyol having a molecular weight of about 40,000 to 130,000;
Up to 90 weight percent of a medium molecular weight polyepoxy resin such as 000 to 10,000 epoxidized octafunctional bisphenol A novolac resin; and, if flame retardancy is desired, preferably about 90 ° C to 11 ° C.
Consisting essentially of about 35 to 90 weight percent of a low molecular weight brominated epoxy resin, such as an epoxidized glycidyl ether of tetrabromobisphenol A, having a melting point of 0 ° C. and a molecular weight of about 600 to 2,500. Includes epoxy resin systems. To this resin system was added a cationic photoinitiator capable of initiating the polymerization of the epoxy resin system described above upon exposure to actinic radiation, Resin 1.
Add about 0.1 to 15 parts per 100 parts; optionally about 1 sensitizer to expose or enhance at the desired wavelength.
0 parts by weight can be added; and the resin system, excluding the photoinitiator and sensitizer, can be used in the wavelength range of 330 to 700 nm for 2.0 mil (0.05 mm) thick films. It further has a feature that the absorbance is less than 0.1.

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a photoimageable coating material which comprises a cationically polymerizable epoxy resin system containing a photoinitiator and optionally a sensitizer. It is a mixture. In one embodiment, this system was specially developed for use as a solder mask on printed circuit boards and for application by curtain coating techniques. However, this system can be used for other applications such as etch masks and can be applied by other methods such as roller coating. In another embodiment, this system is especially adapted for screen coating. In one particular application of the solder mask, the photoimageable material is about 0.5 to 4.0 mils (0.013 to 0.10 mm) or more by conventional curtain coating methods on the substrate. It is curtain coated to thickness, dried, imaged and developed. The developed area exposes the desired metallization at the base of the substrate where the solder should be applied, the remaining solder mask material is allowed to cure, and while solder is applied by conventional techniques, Remains on the substrate as a solder mask.

Thus, the system of the present invention must have sufficient rheological properties to be applied by curtain coating or screen coating techniques, and exposure to radiation in the region where the photoinitiator is photoactive. It must be sensitive or have the necessary physical and chemical properties to resist degradation during the soldering process. Traditionally, solder masks must remain on the substrate after soldering and, therefore, must withstand fire or flame for many uses. In formulating such paints, there are a number of competing ideas that must be considered in order to provide the desired end product. Although no specific type of material has been found that meets all of the various requirements, the combination or blend formulation of various epoxy resins according to the present invention is suitable for photoimageable flame retardant solder mask compositions that can be applied. It has various characteristics required for.

Generally, the epoxy resin system consists essentially of a high molecular weight phenoxypolyol resin which is the condensation product between epichlorohydrin and bisphenol A. A suitable resin of this type is sold by Union Carbide under the trademark PKHC. This resin has an epoxide value of about 0.3 equivalents per kg, that is, a weight of about 37,000 per epoxide, and a Tg (glass transition temperature) of about 98 ° C. The second resin of this system is a medium molecular weight, polyepoxy resin such as an epoxidized octafunctional bisphenol A formaldehyde novolac resin. A suitable resin of this type is loaned under the trademark EpiRez SU-8-
Sold by Poulin. This resin has an epoxide value of about 4.7 equivalents per kg, ie a weight of about 215 per epoxide and a melting point of about 82 ° C. These two resins have the rheological, photolithographic and physical properties necessary for curtain coating for solder masks.

Although flame retardancy is desirable in many cases, these two resins do not exhibit adequate flame retardancy for various applications. In such cases, the third resin in the system is a low molecular weight, high softening point brominated epoxy resin, such as the epoxidized glycidyl ether of tetrabromobisphenol A. Suitable resin of this type is also Epirez 518
It is sold by Loan-Poulin under the brand name of 3. This resin has an epoxide value of about 1.5 equivalents per kg,
It has a weight of about 675 per epoxide and a melting point of about 97 ° C. Each of the above epoxy resins selected within a certain molecular weight range is blended in a certain ratio.

Various photoinitiators such as sulfonium salts, iodonium salts, and ferrocene salts are added to the resin system to provide the appropriate photoresponse to actinic radiation. Since this resin system is cationically photocurable, the photoinitiator must be capable of causing cationic polymerization of the resin upon exposure to radiation. One particularly preferred photoinitiator is the triarylsulfonium hexafluoroantimonate salt complex sold by General Electric Company under the trade name UVE 1014. It is also possible to use another photoinitiator, such as the triphenylsulfonium hexafluorophosphate salt, sold by 3M under the trade name FX 512, and diphenyliodonium hexafluoroantimonate. In some cases
Sensitizers such as anthracene or its derivatives or perylene or its derivatives can also be added, which can increase the response speed of photoimaging and / or wavelength sensitivity.

It is preferred that 10 to 80% of the polyol resins generally have a molecular weight of 40,000 to 130,000, and up to 90% of the epoxidized novolak resins are about 4,000 to 10,000. It has been found to be preferred to have a molecular weight of This is the most common case where flame retardancy is not an issue. However, if flame retardancy is not a required property, it is often desirable. In such a case, the polyol resin is generally one in which about 20 to 40%, preferably 25 to 35%, has a molecular weight of 40,000 to 130,000, and more particularly and preferably 6
It is recognized that ones having a molecular weight of 000 to 90,000 can be used. The epoxidized novolac resin is about 25 to 35% thereof, preferably 25 to 30%.
It is possible to use those in which the% generally has a molecular weight of about 4,000 to 10,000, preferably about 5,000 to 7,000. About 35 to 65%, more preferably about 40 to 45% of the epoxidized brominated bisphenol A is generally about 600 to 2,50.
It is possible to use those having a molecular weight of 0, preferably 1,000 to 1,700. A photoinitiator and optionally a photosensitizer are added to this resin system. Resin type 1
About 0.1 to about 15 parts by weight of photoinitiator based on 00 parts is common and, if required and optional, up to about 10 parts by weight photosensitization based on 100 parts of the resin system. Agents can be used.

A particular composition is chosen to optimize the desired characteristic values. For example, PKHC adjusts the rheology of the applied material, Epirez 5183 imparts flame retardancy to the material, and Epirez SU-8 provides fast photosensitivity and improved resolution. It will be appreciated that in selecting a particular amount of each resin, increasing the concentration of any one of the resins will increase the properties associated with it, while increasing any one of the specific resins will result in One or two concentrations will require a reduction, which will result in a decrease in the function of certain properties associated with them. Reduction of either resin below the broad range of percentages mentioned above is unacceptable for the specific purpose of flame-retardant, high-resolution, photoimageable solder mask materials that are curtain coatable or screen coatable. Will invite nature.

As the amount of PKHC is reduced, the rheological properties obtained lead to a lower coverage when the material is applied, and the resulting materials become very brittle. Epiles 518
A reduction of 3 reduces the flame-retardant properties of the resulting system, and if below the specified broad range lower limit, the flame-retardant properties meet certain industrial requirements, such as UL 94 VO flammability requirements. I will not do it. However, Epirez 5183 does provide some flame retardant properties in any amount. When Epirez SU-8 concentration is reduced, a slower photospeed and lower resolution result in a balance of material prescriptions, all of these requirements must be considered and to obtain the desired result, The final product must be optimized to give satisfactory property values.

The following formulations have been found to work very well as solder mask compositions.

[0015]

[Table 1] Note: *% by weight ** parts by weight per 100 parts of resin (a) Measured with a rheometry viscoelastic spectrometer, Model 7700, for parallel plates with 1-inch (2.5 cm) intervals (b) Measured using Perkin-Elmer DSC7 (c) Logarithm of accumulated elastic modulus at 100 ° C

Each of the examples was mixed in a propylene glycol monomethyl ether acetate (PGMEA) solvent,
These formulations are approximately 40% solids in PGMEA. Each of these formulations in this solvent is applied very well on the circuit board. However, other moderately polar solvents,
For example, propylene glycol monomethyl ether, 2-
Methoxyethanol, 2-methoxyethyl acetate,
2-Ethoxyethyl acetate, N-methylpyrrolidone, propylene carbonate, gamma butyrolactone or the like can be used.

The preferred formulation for the solder mask is in Example 4.

The following curtain coating techniques were used for the application of photoimageable material to a substrate through a "curtain" of free-falling material. The material is coated as the substrate passes through this curtain. The curtain coating device includes a pan, a pump, a viscosity controller, and a coating head. The coating material is pumped from the pan to the coating head to form the curtain. This curtain falls back into the pan and returns, always repeating this. However, as the substrate passes through this curtain, material is deposited on it. Viscosity range of coating liquid is 200 to 2.0
At 00 cps, the dry thickness of the film deposited on the substrate is generally 0.5 to 4.0 mils (0.013 to 0.10 m).
m) range.

Other types of coating such as roll coating and wire wound rod coating can also be used. We will discuss the specific formulation for screen coating in due course.

Each of these particular blends of epoxy resin and photoinitiator were applied very well by the curtain coating process with no spaces or gaps, about 2 mils (0.05 m).
Cover the circuit board to the thickness of m). During photoimaging, light passes through the coating to the underlying structure of the substrate and is essentially completely transmitted; thus the coating, excluding the photoinitiator and sensitizer, is transparent to the particular light. That is, it has an absorption of less than 0.1 for a 2.0 mil (0.05 mm) thick film.

The solder mask material is exposed to UV radiation from a medium pressure mercury lamp. UV radiation is passed through the opaque master in the areas where the solder mask is to be removed.
After exposure to UV radiation, the circuit board is briefly baked to facilitate the crosslinking reaction initiated by the photolysis products of the sulfonium salt. Bake temperature is 100 ° to 1
The baking time is 2 to 20 minutes at 50 ° C. The solder mask is then developed using a solvent that readily dissolves the unexposed material. One such developer is DY90 marketed by Ciba-Geigy, which contains butyrolactone, propylene carbonate, and diglyme, but butyrolactone alone is fully useful as a developer. Spray-developers and other means of physical stirring of the developer are also used. Curing of the solder mask is accomplished by exposing the solder mask to radiation and then baking in an oven at 150 ° C. The UV light irradiation is changed to 1 to 4 J / cm ² , and the baking time is changed to 30 to 90 minutes. The coated and cured Tg values are shown in Table 1 for some samples.

After removing surface oxides, such as with a light HCl wash, and applying an antioxidant such as benzotriazole, the circuit board can be soldered using a variety of methods. Two of the methods performed using the solder masks described herein are flow soldering and vapor phase soldering.

Fluid soldering consists of placing each component on a circuit board, applying a flux to the metal surface to be soldered, and passing the assembly through a continuous stream of molten solder. ing. Vapor phase soldering is performed by applying solid solder and flux to the exposed metal surface on the substrate by screening techniques or other suitable techniques. After placing the components on the circuit board, the assembly is passed through steam maintained at a temperature above the melting point of the solder.

Sample 4 was tested for solderability in the conventional manner using the "Soldering Shock" test below. This method is common in testing the behavior of solder masks under the stress of typical soldering found in industrial processes.

Photo-imaging the coated substrate,
Develop and fully cure. This part is 500
Dipped in molten solder for 10 to 20 seconds at ° F ± 25 ° (260 ° C ± 13.9 °). After soaking in this solder, the parts were allowed to cool to room temperature and inspected. crack,
A visual inspection was performed for flaking flakes, blisters, or significant deterioration of the material. If the soldering shock does not physically degrade the material, as confirmed by visual inspection, the solder mask passes the shock test criteria.

Certain additives may be desired for formulations for some applications. For example, fluorescent agents or dyes can be added for inspection or cosmetics. It normally contains a quantity of about 0.001 to about 1 part by weight per 100 parts by weight. Such species that have been used are, for example, malachite green oxalate, ethyl violet, and rhodamine B. For some other applications it is desirable to use a surfactant, such as Fluorad FC430 sold by 3M. Surfactants will normally be included in amounts of 0.01 to 1 part by weight per 100 parts by weight.
It will of course be understood that this additive should not significantly degrade the other properties of the coating.

Table 2 below shows some of the preferred embodiments with various additives.

[0028]

[Table 2] Note: a-wt% b-parts by weight per 100 parts by weight of resin c-fluorad FC430 * malachite green ** ethyl violet

Table 3 shows 3 using PKHC and SU-8.
Two examples are shown. These are useful when flame retardancy is not needed.

[0030]

[Table 3]

Examples 10 and 11 have good properties for curtain coating and are used as solder masks. On the other hand, Example 12 has good properties in general, but 10
Log G'at 0 ° C is slightly low. This low value makes it less adaptable, so it will find particular use in solder mask applications, but may find use in other applications.

Various other types of resin formulations have been found to be unsuitable, either rheologically and / or lithographically, as photoimageable solder masks that can be curtain coated.

The present invention has been particularly described above as a solder mask material for curtain coating. However,
It can be used for other purposes and can be applied by various other methods such as roller coating. If different applications and application techniques are used,
Certain modifications of the preferred materials may be necessary to meet different needs. For example, different solvents or viscosities may be desired, unlike curtain coating, for roller or spray coating, and rheological properties may be altered from those optimal for curtain coating for other types of use. That will be the case.

If screen coating of this type of photoimageable material is required, its rheology is modified by the addition of a thixotropic agent to this material and this is done using conventional screen techniques. It has been found that this is best achieved by making the screen suitable for wiping on the substrate.
When a thixotropic agent is added to a composition with the other properties required, it becomes a relatively thin flowable material when under shear and also when it has no or very little shear. , And becomes a gel-like substance. Although a variety of different types of thixotropic agents can be used, preferred ones have a particle size of less than about 5.0 μm, preferably less than about 2.0 μm, and more preferably about 0.001 to 0.5 μm. It is amorphous silicon dioxide.

The screen coating technique is a full screen screen whereby the material is applied in a continuous manner onto the substrate and subsequently imagewise photoimaged to reveal where solder is to be applied. It Alternatively, the material can be screened in a pattern on the substrate so that it is masked open up where it is not needed.
Those skilled in the art will appreciate that these two methods require materials with different optimum viscosities and thixotropic indices. The amount of thixotropic agent added will vary widely depending on the screening characteristics required. For silica this can be up to about 20% by weight. The preferred range for amorphous silica is from about 1 to about 12%.

In addition, one of the properties required for a dried film, as described above, is that the light can penetrate enough to activate all photoinitiators in the path through the thickness of the film. , Having a sufficiently low light absorption within the region that activates the photoinitiator. More precisely, it can be regarded as a sufficiently high transmission of light energy within the photoactive region of the photoinitiator, but it can be routinely characterized by the absorptance measured by spectroscopic optics. The absorptance of the film, measured by a spectrophotometer, should be less than about 2.0 per mil (0.025 mm) of film thickness with light in the photoactive region of the photoinitiator.

It will be appreciated by those skilled in the art that some of the absorptivity measurements of films containing silica particles, especially those of large diameter, are due to light scattering rather than molecular or atomic absorption. In other words, this is at least about 1% per mil of film thickness when the film is in the range of 1 to 2 mils (0.025 to 0.05 mm) thick.
It means that it must have a light transmittance of. However, if the film were thicker, it would require a higher transmission, or lower absorption, to properly expose the entire thickness of the film. This can be confirmed by routine experiments. As mentioned above, this transmission or absorption is only related to the wavelength required to activate the photoinitiator. UVE 1014 alone is sensitive to radiation at wavelengths of 200 to 370 nm. However, most glass or other substrates in artwork absorb all energy below about 320 nm. In this case the film exposed through the artwork will be sensitive to radiation of 320 to 370 nm. For other photoinitiators and artwork substrates, the critical range of exposure energy will be different.

It is understood that this absorptivity measurement was made on the dried film after it had been coated on the substrate, and thus included the photoinitiator as well as the resin and thixotropic agent. Expressed in another way, the absorptivity, which must be 2.0 or less, is the cumulative effect of all these components, the resin system, the photoinitiator, and the thixotropic agent, either of them individually. Not one thing.

To demonstrate the effect on various properties of the photoimageable material, various amounts of various types of thixotropic agents were added to solutions of standard resin systems at various concentrations. The standard resin system is as follows. Standard resin type PKHC 28.54% Epirez 5183 42.81% Epirez SU-8 23.79% UVE 1014 4.76% Ethyl violet 0.07% FC-430 0.03%

This standard resin system was used to make various solvent% screen coatable materials with several different types and amounts of thixotropic agents, which were then tested for viscosity and photoimaging properties. did. Table 4 below shows that six of these standard resin systems dissolved in PGMEA, to which amorphous fumed silicon dioxide sold under the tradename Aerosil A380 by Degussa, was added as a thixotropic agent, Separate batches are shown. The percent of total solids including the resin system, the amorphous silica thixotropic agent and the photoinitiator is about 50 solids.
% And solvent about 50%. Viscosity is 1 to 10 with Brookfield RTV viscometer using No.7 spindle
The measurement was performed at 25 ° C. at a rotation speed of 0 rpms. These four
The thixotropic index is shown for each of the batches. The index for each of these batches was defined as the viscosity at 25 ° C, 5 rpm divided by the viscosity at 25 ° C, 50 rpm, although other ratios can be used.

[0041]

[Table 4] Note: All samples used were standard resin system dissolved in PGMEA plus 3% of total (including solvent) Aerosil A380, and all solids including resin system, photoinitiator and thixotropic agent were used. 50% solvent and 50% solvent 2 Brookfield RTV viscometer No.
7 spindle revolutions

Table 4 shows that there is a thixotropic amount of change between the low and high rpm measurements, and that the thixotropic index is the same for each batch nominally containing the same amount of components. This change may be due to the inherent changes in the material as well as the different mixing conditions.

Table 5 below shows 3.5% of Aerosil A3
The same preferred resinous batch having 80, but about 47% total solids including resin system, photoinitiator and thixotropic agent and about 53% solvent is shown. 3.0%
There was a significant increase in the actual viscosity at low rpm and a decrease at high rpm, as seen in Table 5, which increased the amount of thixotropic agent to 3.5% and also decreased the total amount of solids. The thixotropy index increased to 8.3.

[0044]

[Table 5]

Both the compositions of Tables 4 and 5 are generally suitable for blanket screen coating. Example 19 is preferred over each of the examples in Table 4 for patterned screening. In the case of patterned screening, the desired pattern is screened onto the substrate and the patterned coating is then dried and cured.

Compositions of the standard resin system with minor modifications are shown in Table 6 below, with varying percentages of different types of thixotropic agents added.
(Although malachite green oxalate was replaced with ethyl violet as the dye, the resin was in all respects the same as the standard resin system described above, along with other additives, including photoinitiators). In each of these compositions the UVE 1014 was 4.76% as solids in the basic formulation and also the total solids with the percentage of added thixotropic agent shown as% of the total system including the resin system, photoinitiator and PMGEA solvent. Was 41%. Table 6 shows the percentage of each additive.

[0047]

[Table 6] Note: 1 A380 is fumed silica sold by Degussa 2 A300 is fumed silica sold by Degussa 3 R974 is fumed silica surface-hydrophobicized 4 R972 is fumed silica surface-hydrophobicized, R9
Particle size larger than 74 5 R202 is fumed silica with surface hydrophobization 6 TS720 is fumed silica with surface hydrophobization (made by Cabot) 7 TS710 is fumed silica with surface hydrophobized with silane (cabot) 8) HDK-N20 is a fumed silica 9 Percentage added to the total solution (solid + solvent)

Table 7 below shows 1 rpm, 100 rpm, and 1 rpm.
3 shows the viscosities of Examples 20-32 measured with a rotational viscometer at rpm. The rotation sequence was increased from 1 rpm to 100 rpm and then reduced to 1 rpm to check recovery.

[0049]

[Table 7]

All the above coatings were first evaluated for photoimaging. Examples 20, 23, 25 and 27
It was not appraised in a screen coating test as it had a measurable degree of photoimaging and was therefore better than the other samples. Examples 21, 22, 2
4, 26, 28, 29, 30, 31 and 32 were evaluated for photo image resolution and screen coating properties. Examples 21 and 2 regarding resolution and photo-imaging property
2, 23, 24, 26, 30 and 31 were preferred over the others. Regarding screen coatability, Examples 21, 24, 26, 29 and 30 were more preferable than the other examples.

A general evaluation based on both the screen characteristics and the photographic processability and each of the other characteristics is made in Example 30.
Was best, 21 was second, and 28 was third.

In another experiment, when the thixotropic agent was in the range of about 2.5-3.5%, the resin system, photoinitiator,
It has been found that the total solids content, including the thixotropic agent and the thixotropic agent, should not exceed about 53%, otherwise the performance of the screening process and the quality of the coating will be reduced. On the contrary, the total solids content should not fall below about 40%.

Accordingly, by adding an appropriate amount of a thixotropic agent and appropriately selecting and controlling the balance between the percent solids in solution and the appropriate thixotropic agent, the substrate can be screened and then photoimaged. A material is obtained which can be processed and developed.

Exposure and development of the photoimaging composition can be accomplished essentially as described above. A preferred technique for exposing and imaging the screened material is as follows: the material is screened onto a substrate and then dried at about 88 ° C. for about 15 minutes as described above to give an essentially continuous solid film. A solid film is obtained, which is essentially a tack free coating. The coating is then imagewise exposed to about 1500 mJ / cm ² of light from a low pressure Hg arc lamp and then about 1 in a conventional batch oven.
Bake at 20 ° C. for about 12 minutes. The exposed and baked coating is coated with gamma-butyrolactone at a pressure of about 3.5 bar and a residence time of about 4 minutes to about 28 to develop the pattern.
Developed by spraying at ° C. The patterned developed coating is then exposed to about 4 J / cm ² of ultraviolet light and then baked in an oven at about 150 ° C. for about 60 minutes. The resulting patterned and developed coating on the circuit board shows excellent solder resistance properties when used as a solder mask and tested by the methods described above.

1) About 40,000 to about 130,000
About 20 to about 60 polyols, which are condensation products of epichlorohydrin having a molecular weight of 0 and bisphenol A
% By weight; up to about 35% by weight of epoxidized octafunctional bisphenol A formaldehyde novolac resin having a molecular weight of about 4,000 to about 10,000; and having a softening point of about 60 ° to about 110 ° C. and about 60
An epoxy resin system consisting essentially of about 35 to about 80% by weight of an epoxidized glycidyl ether of tetrabromobisphenol A having a molecular weight of 0 to about 2,500; said epoxy upon exposure to actinic radiation. About 0.1 of the cationic photoinitiators that can initiate the polymerization of the resin system.
1 to about 15 parts by weight; where the resin system and photoinitiator described above are to be treated in a solvent; and about 20% as a thixotropic agent dispersed in the solvent with the resin system and photoinitiator. An effective amount of silica up to 1; a film thickness of 1 mil (0.1%) when the imaging system is dried onto a film.
Photosensitive cationically polymerizable epoxy-based imaging system further characterized by having a light absorption coefficient of less than 2.0 per 025 mm) within the photoactive region of the photoinitiator.

2) The imaging system is about 25 to 35
% Polyol resin, about 20 to 30% epoxidized octafunctional bisphenol A formaldehyde novolac resin, about 40 to 45% epoxidized glycidyl ether of tetrabromobisphenol A, and about 2 to 5 parts by weight cationic photoinitiator. The invention according to item 1, which is an agent.

3) The molecular weight of the polyol resin is about 60,
000 to 90,000, the epoxidized octafunctional bisphenol A formaldehyde novolac resin has a molecular weight of about 5,000 to 7,000, and the epoxidized glycidyl ether of tetrabromobisphenol A has a molecular weight of about 1,000 to The invention according to item 1, which is 1,700. 4) Includes an effective amount of photoinitiator up to 10%, the preceding 1
The invention described. 5) The invention according to item 1, wherein the photoinitiator is a sulfonium salt having photoactivity in the region of 330 to 370 nm. 6) The invention according to item 1, wherein the solvent is propylene glycol monomethyl ether acetate. 7) The imaging system according to item 1, wherein the silica is amorphous silica having a particle diameter of less than about 5 μm.

8) The imaging system as described in 7 above, wherein the particle diameter of silica is less than about 2.0 μm. 9) Silica particle diameter is about 0.001 to 0.5 μm
The imaging system according to item 7 above. 10) The imaging system according to item 7, wherein the amount of silica is between about 1 and 12%.

11) About 40,000 to about 130,0
About 10 to about 8 polyols which are condensation products of epichlorohydrin having a molecular weight of 00 and bisphenol A
0% by weight; epoxidized octafunctional bisphenol A having a molecular weight of about 4,000 to about 10,000
An epoxy resin system consisting essentially of from about 20 to about 90% by weight formaldehyde novolac resin; about 0 of a cationic photoinitiator capable of initiating the polymerization of said epoxidized resin system upon exposure to actinic radiation. .1 to about 15 parts by weight; wherein the resin system and photoinitiator are to be treated in a solvent; and about 20 as a thixotropic agent dispersed in a solution with the resin system and photoinitiator. %
An effective amount of silica; up to 2.0 per mil (0.025 mm) of film thickness when the imaging system is dried onto a film.
A photosensitive, cationically polymerizable, epoxy-based imaging system, further characterized by having a light absorption of less than less than within the photoactive region of the photoinitiator.

12) Further, about 5 parts of epoxidized glycidyl ether resin of tetrabromobisphenol A is added.
The invention of claim 11 characterized by an effective amount of 0 weight percent. 13) The invention according to item 11, wherein the polyol resin has a molecular weight of about 60,000 to 90,000 and the epoxidized octafunctional bisphenol A formaldehyde novolac resin has a molecular weight of about 5,000 to 7,000. .. 14) Includes an effective amount of sensitizer up to 10%, and
Invention of 1. 15) The invention described in 11 above, wherein the photoinitiator is a sulfonium salt having photoactivity in a region of 200 to 370 nm. 16) The invention described in 11 above, wherein the solvent is propylene glycol monomethyl ether acetate. 17) The imaging system according to item 11, wherein the silica is an amorphous silica having a particle diameter of less than about 5.0 μm.

18) The imaging system according to item 17, wherein the particle diameter of silica is less than 2.0 μm. 19) The particle diameter of silica is about 0.001 to 0.5μ.
18. The imaging system according to item 17, which is m. 20) The imaging system according to item 17 above, wherein the amount of silica is between about 1 and 12%.

21) Solid epoxy base resin system consisting of about 10 to 80% by weight of high molecular weight polyol resin having epoxy functionality; about 20 to 90% by weight of medium molecular weight polyepoxy resin; to actinic radiation An effective amount of up to about 50% by weight of a cationic photoinitiator capable of initiating polymerization of the epoxidized resin system upon exposure to light; wherein the resin system and photoinitiator are treated in a solvent. And an effective amount of silica up to about 20% as a thixotropic agent dispersed in a solvent together with the above resin system and a photoinitiator; The photosensitive coating is further characterized in that it has a light absorptivity of less than 2.0 per mil (0.025 mm) of film thickness when dried within the photoactive region of the photoinitiator. On polymerizable epoxy based imaging system.

22) The imaging system as set forth above in 21, wherein the solvent is propylene glycol monomethyl ether acetate. 23) The imaging system of item 21 above, wherein the silica is amorphous silica having a particle diameter of less than about 5.0 μm. 24) The imaging system according to the above item 23, wherein the particle diameter of silica is smaller than about 2.0 μm. 25) Silica particle diameter is about 0.001 to 0.5μ.
24. The imaging system according to item 23 above, which is m. 26) The imaging system according to item 23 above, wherein the amount of silica is about 1 to 12%.

The present invention is capable of various adaptations and modifications without departing from the scope of the present invention as defined in the claims.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Norman Old Ritchie Cards, Georgia 14859, New York, USA. Locked wood. main Street. Box 62 (72) Inventor Richard Allen Day USA New York 13862. White Tony Point. Earl Day Number 1. Box 320 A (72) Inventor Ramkuri Shiuna Gosal 12065, New York, USA. Clifton Park. Cathedral Court 10 (72) Inventor Donald Herman Grazell, Pennsylvania, USA 18834. New Milford. Earl Day Number 2. Box 274 (72) Inventor David Jyon Rutsel 13732, New York, USA. Apalachin. Lily Hill Road 1913

Claims (3)

[Claims] 1. A polyol, which is a condensation product of epichlorohydrin having a molecular weight of about 40,000 to about 130,000 and bisphenol A, of about 20 to about 60% by weight; a molecular weight of about 4,000 to about 10,000. Epoxidized octafunctional bisphenol A formaldehyde novolac resin having up to about 35% by weight; and of tetrabromobisphenol A having a softening point of about 60 ° to about 110 ° C and a molecular weight of about 600 to about 2,500. About 3 epoxidized glycidyl ethers
An epoxy resin system consisting essentially of from 5 to about 80% by weight; and from about 0.1 to about 15 of a cationic photoinitiator capable of initiating polymerization of said epoxy resin system upon exposure to actinic radiation. Parts by weight; where the resin system and photoinitiator described above are to be treated in a solvent; and effective up to about 20% as a thixotropic agent dispersed in the solvent with the resin system and photoinitiator. An amount of silica; wherein the imaging system, when dried on a film, has a light absorptivity of less than 2.0 per 1 mil (0.025 mm) of film thickness of the photoinitiator. A photosensitive cationically polymerizable epoxy-based imaging system, further characterized by having in the active region. 2. A polyol, which is a condensation product of epichlorohydrin having a molecular weight of about 40,000 to about 130,000 and bisphenol A, of about 10 to about 80% by weight; a molecular weight of about 4,000 to about 10,000. An epoxy resin system consisting essentially of from about 20 to about 90% by weight of an epoxidized octafunctional bisphenol A formaldehyde novolac resin having a polymerization of the epoxidized resin system upon exposure to actinic radiation. From about 0.1 to about 15 parts by weight of the cationic photoinitiator which can be initiated;
Wherein the resin system and photoinitiator are to be treated in a solvent; and an effective amount of silica up to about 20% as a thixotropic agent dispersed in a solution with the resin system and photoinitiator. And an imaging system comprising the following: when the imaging system is dried on a film, a light absorptivity of less than 2.0 per 1 mil (0.025 mm) of film thickness is within the photoactive region of the photoinitiator. A photosensitive, cationically polymerizable, epoxy-based imaging system, further comprising: 3. A solid epoxy-based resin system comprising about 10 to 80% by weight of a high molecular weight polyol resin having epoxy functionality; and about 20 to 90% by weight of a medium molecular weight polyepoxy resin; to actinic radiation. An effective amount of up to about 50% by weight of a cationic photoinitiator capable of initiating polymerization of the epoxidized resin system upon exposure to light; wherein the resin system and photoinitiator are treated in a solvent. Shall be;
And an imaging system comprising the resin system and an effective amount of silica up to about 20% as a thixotropic agent dispersed in a solvent together with the photoinitiator, when the imaging system is dried on a film. , A photosensitive cationically polymerizable epoxy-based imaging system further characterized by having a light absorptivity of less than 2.0 per mil (0.025 mm) of film thickness within the photoactive region of the photoinitiator.