JPS5839445B2 - Heat-resistant photosensitive material with excellent storage stability - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat-resistant photosensitive material, and more particularly to a photosensitive material that is photochemically cured to provide a heat-resistant substance.

In recent years, there has been a high demand for heat-resistant photosensitive materials, mainly in the electronics industry.

It is being applied as a protective material, insulating material, solder resist, adhesive, coating material, etc. in the electronic field, and as a heat-resistant photoresist in the manufacture of semiconductor devices.

This type of photosensitive material is not only required to have excellent photocurability and heat resistance after photocuring, but also to exhibit good adhesion to the adherend. It is also desired that the material satisfies basic properties such as insulation properties, moisture resistance, and chemical resistance.

On the other hand, from the viewpoint of pollution-free, resource-saving, and engineering-energy saving, it has the ability to form a film without any solvent or with a small amount of solvent, and furthermore, the photosensitive material in such a state gels over time before use. It is desired that the product has excellent storage stability without causing any problems.

However, there are few conventional photosensitive materials that satisfy all of these required properties.

In general, those with excellent photocurability tend to have poor storage stability, and many also lack adhesive strength to adherends.

For example, an unsaturated ester imide that has an imide bond capable of imparting heat resistance in a chain molecule and has a photocurable carbon-carbon double bond at both ends of the molecule, which provides a heat-resistant substance by photocuring. Compounds are known, but these types of compounds have problems such as insufficient stability during storage and poor adhesive strength.

From this point of view, the present invention has excellent storage stability, has the originally required good photocurability and heat resistance, and satisfies all of the above-mentioned required properties, including excellent adhesion to adherends. The purpose is to provide a new and useful heat-resistant photosensitive material.

That is, in this invention, the acid component that forms a chain ester bond with the glycol has one photopolymerizable carbon-carbon double bond in the molecule.
0 per mole of tribasic acid and this tribasic acid
．． A tribasic acid containing an imide bond in the molecule represented by the following general formula in which the ratio is 1 to 0.35 moles; An unsaturated esterimide compound that is liquid or semi-solid at room temperature and has free hydroxyl or carboxyl groups at both ends of the molecule, and 50 parts by weight per 100 parts by weight of this compound.
The present invention relates to a heat-resistant photosensitive material having excellent storage stability, characterized in that the main component is a photosensitizer in a proportion of up to 1 part by weight.

As described above, the heat-resistant photosensitive material of the present invention has as its main components a tribasic acid having a photopolymerizable carbon-carbon double bond in its molecule and a tribasic acid represented by the above general formula containing an imide bond in its molecule. This compound uses an unsaturated ester imide compound made by esterifying two types of tribasic acids and glycol into a chain, and this compound has a specific proportion of imide bonds and light in the chain molecule. It is characterized by having a polymerizable carbon-carbon double bond, while free hydroxyl or carboxyl groups remain at both ends of the chain molecule.

Such unsaturated esterimide compounds are liquid or semi-solid at room temperature and have excellent film-forming ability even with no solvent or a small amount of solvent. It has excellent storage stability without causing any problems.

On the other hand, when used for convenience purposes, it can be easily photocured due to the photopolymerizable carbon-carbon double bonds within the chain molecules, and the cured film exhibits excellent heat resistance due to the imide bonds within the chain molecules.

Further, the adhesion between the cured film and the adherend is good, and there is an advantage that etching treatment on the surface of the adherend, which was conventionally considered indispensable for improving adhesive strength, is not necessary.

In addition, this type of coating has excellent properties such as insulation properties, moisture resistance, and chemical resistance, and can ultimately satisfy all of the above-mentioned required properties as a heat-resistant photosensitive material.

The tribasic acid containing an imide bond in the molecule represented by the above general formula used in this invention is diamino (H2
, N-R-NH2) and 2 moles of trimellitic anhydride.

Here, as a diamine, R is, for example, +CH2+2-÷
In addition to aliphatic diamines such as CH2+4, various aromatic to alicyclic diamines in which R is represented by the following structural formula are included.

A photopolymerizable carbon group in the molecule used in this invention, such as a carbonyl group,
Examples of tribasic acids having one carbon double bond include fumaric acid, maleic acid, itaconic acid, citraconic acid, and acid anhydrides thereof.

The ratio of the above two types of tribasic acids used is 1 mole of the tribasic acid that has one photopolymerizable carbon-carbon double bond in the molecule, and the tribasic acid that contains an imide bond in the molecule. Acid is 0.1~
It should be in the range of 0.35 moles.

If it is less than 0.1 mole, storage stability, heat resistance properties after curing, moisture resistance, chemical resistance, etc. will deteriorate, and conversely, if it is less than 0.1 mole, the storage stability, heat resistance properties after curing, moisture resistance, chemical resistance, etc. will deteriorate.
If the amount exceeds 35 moles, the film-forming ability will decrease, the solubility in solvents will be poor, and furthermore, problems may arise in terms of photopolymerizability, and neither of these is suitable as a heat-resistant photosensitive material.

On the other hand, glycols to be esterified with these tribasic acids include ethylene glycol, diethylene glycol, and triethylene glycol.
) Ropylene glycol, dipropylene glycol, butanediol, pentyl glycol, neopentyl glycol,
Examples include hexanediol.

The unsaturated ester imide compound in this invention is usually used in a relatively excess amount in a mixture of a tribasic acid containing an imide bond in the molecule and a tribasic acid containing a photopolymerizable carbon-carbon double bond in the molecule. It is produced by adding glycol and causing a heating reaction, then distilling off unreacted glycol under reduced pressure, and then further heating the reaction to achieve a high degree of condensation.

Other methods include esterifying glycol with one of the tribasic acids, usually a tribasic acid containing an imide bond in the molecule, and then adding the other tribasic acid to this and causing a heating reaction. But it can be made.

The molecular structure of the unsaturated esterimide compound produced by these methods is not necessarily constant and varies depending on the reaction form, the number of reaction moles, etc.

For example, according to the first manufacturing method, the following general formula (1) is obtained.

A mixture of various structures including the compound shown in (2) is obtained.

However, what is important is that the chain molecule has an appropriate proportion of imide bonds and photopolymerizable carbon-carbon double bonds derived from each tribasic acid, and that it has a free hydroxyl group at the end of the chain molecule. or have a carboxyl group.

General formula (1)> (However, in both formulas (1) and (2), Ro is a tribasic acid residue containing an imide bond in the molecule, R2 is a glycol residue, and R3 is a Tribasic acid residue containing a polymerizable carbon to carbon double bond, no2mo is an integer of 0 or more, nl
, R2 are integers of 1 or more, ml and m2 are integers, and one of them may be O.

) Moreover, such an unsaturated ester imide compound has a hydroxyl value of 0.2 to 1.5 IJ equivalent/g and an acid value of 0.
The range is preferably 1 mm IJ equivalent/g or less.

The reason for this is that if the hydroxyl value becomes too low, it becomes a high molecular weight product that may impair storage stability and adhesive properties, while if it becomes too high, it tends to have a negative effect on properties such as chemical resistance. This is because if the acid value becomes too high, problems mainly arise in moisture resistance.

The heat-resistant photosensitive material of the present invention contains the above-mentioned unsaturated esterimide compound as a main component, and this compound alone has photocuring ability.

However, it is generally desirable to add an appropriate photosensitizer to the above compound to improve the photocuring rate.

It has been found that the addition of such a photosensitizer does not adversely affect the storage stability that is characteristic of this type of material.

Examples of the photosensitizer include benzoin, benzoin methyl ether, benzoin isopropyl ether, benzine, carbonyl compounds such as benzyl dimethyl ketal, organic sulfur compounds such as benzyl sulfide, halogen compounds, and photoreducible dyes.

The amount of the photosensitizer used is preferably 5.0 parts by weight or less per 100 parts by weight of the unsaturated esterimide compound.

If the amount is too large, the effect on storage stability etc. cannot be ignored.

In addition, in this invention, when a known organic peroxide is used as a thermosetting catalyst together with a photosensitizer, the effect of improving the curing function can be obtained when heat treatment is further performed as a post-treatment after photocuring. Catalysts tend to impair the storage stability of photosensitive materials.

Therefore, when using this, consideration must be given to minimizing the amount used and also using an appropriate stabilizer.

In addition to the above-mentioned components, the heat-resistant photosensitive material of the present invention may contain known additives such as fillers and adhesion aids, if necessary.

In addition, for resist materials such as heat-resistant photoresists, small amounts of appropriate organic solvents such as toluene, acetone, and tetrahydrofuran are blended, and vinyl monomers,
A polymerizable unsaturated compound such as a divinyl compound or an unsaturated polyester resin may be blended to reduce the viscosity during film formation.

The heat-resistant photosensitive material of the present invention thus obtained has excellent storage stability, and does not gel in a short period of time even when left in liquid or solution form at room temperature.

However, when storing for a long period of time, it is preferable to store it in a dark room or in a cold room, taking into account its photosensitivity.

On the other hand, for toilet use, it is usually heated to 50-100'C to make it fluid (of course, if it is in a liquid or solution form at room temperature, there is no need to heat it), and then applied to the adherend using a bar coater, applicator, spinner, etc. After coating, a photocured film with excellent adhesive properties can be formed by irradiating active light to photocure and, if necessary, performing post-heat treatment to further improve heat resistance and adhesion. .

Examples of this invention will be described below.

Example 1 Put 1.0 mol of 4,41-diaminodiphenylmethane and 2.0 mol of trimellitic anhydride into a fourth flask,
Add N-methyl-2-pyrrolidone, stir while blowing nitrogen gas, and raise the temperature from room temperature to 150°C.
The reaction was heated at 0 to 160°C for 2 to 3 hours.

By placing the contents of the reactor in ethanol and washing with an alkaline solution, a tribasic acid having a structure represented by the above general formula and an imide bond in the molecule (hereinafter referred to as imidic acid) was produced.

This imidic acid 5g (0,009 mol) and fumaric acid 4.2
．． ! i' (0,036 mol) (the number of moles of the above imidic acid per 1 mol of fumaric acid corresponds to 0.25 mol)
, mix and add this to 100g of ethylene glycol,
Stir while blowing nitrogen gas, and heat from room temperature to 190℃
After raising the temperature to , the mixture was heated and reacted for 6 hours.

After that, excess ethylene glycol was distilled off under reduced pressure, and in order to further increase the degree of condensation, about 0 ml was heated at 200°C under reduced pressure.
A semi-solid unsaturated ester imide compound was produced by heating and reacting for 3 to 4 hours.

The acid value of this compound was O, and the hydroxyl value was 0.49 meq/g.

3 parts by weight of benzoin isopropyl ether as a photosensitizer was added to 100 parts by weight of this unsaturated esterimide compound, and the mixture was heated and dissolved to obtain the heat-resistant photosensitive material of the present invention.

The photosensitive material of Example 1 was subjected to a storage stability test and two types of photocuring performance tests, and the results were as follows.

■ Storage stability test Using tetrahydrofuran as an organic solvent, mix and dissolve 30 parts by weight of the above-mentioned heat-resistant photosensitive material in 100 parts by weight of this solvent to form a solution, and leave it at room temperature for oral administration. Changes in properties were investigated.

As a result, no gelation occurred even after 30 days, and no change in properties was observed visually.

2 Photo-curing performance test - (1) The above heat-resistant photosensitive material was heated to 80°C to form a uniform liquid, and while maintaining this heated state, it was coated onto an adherend to a thickness of 10 μm using a bar coater. A beautiful coating film with a tacky surface could be formed.

After this coating, a 20C
It was photocured by irradiating rIL from a remote position for 5 minutes.

The results of investigating the following characteristics of the photocured films formed by the above method using Sample A when using a 100μ polyester film as the adherend and Sample B when using 50μ copper foil as the adherend were as follows. The results were as shown in Table 1 below.

<Photocuring ability> Regarding sample A, stickiness was no longer observed in the coating within a few seconds after irradiation with light, and the quality of the cured state after 5 minutes of irradiation was examined.

The parentheses in Table 1 indicate the time (in seconds) when no stickiness is visible.

<Adhesiveness> For Samples A and H, the cured film was cross-cut into two squares, Nitto Electric Industries Co., Ltd.'s Seat 29 cellophane tape was crimped onto the cross-cut, and then peeled off. The number of peeled pieces in 100 cross-cuts was I looked into it.

Heat resistance> Samples A and B were subjected to stress heat treatment at 150°C and 150°C for 120 hours, and the cured films were examined to see if there were any abnormalities such as deterioration or peeling.
No abnormalities were considered good, and cases where abnormalities were observed were considered poor.

<Solder heat resistance> Sample B was immersed in a solder bath at 260±5°C for 10 seconds, and the cured film was checked to see if there were any abnormalities such as blistering or peeling. Cases where this was observed were considered poor.

Moisture resistance> When sample B was left in an atmosphere of c+o% RFI at 40°C for 120 hours, it was checked to see if any abnormalities such as rusting of the copper foil or devitrification of the cured film were observed. Those without were considered good, and those with abnormalities were considered poor.

<Chemical resistance> Samples A and B were immersed in toluene, tetrahydrofuran, and ethanol for 1 hour at 25°C, and the cured films were examined to see if any abnormal phenomena such as blistering or peeling were observed. The case where no abnormality was observed was judged as good, and the case where abnormality was observed was judged as poor.

(To) In this test, various substrates other than polyester film and copper foil were used as adherends, such as glass, aluminum plate, stainless steel plate, Kapton film, nickel plated plate, aluminum plated plate, etc. When I measured it, everything was ``0'' except for the stainless steel plate which was ``50''.

For stainless steel plates, after light curing, Post-heat treatment at 230°C for 15 minutes As a result, it became "0".

Next, the temperature dependence of volume resistivity was investigated for the cured film (sample B) formed by the above method and for the film that was further heat-treated after light irradiation. It was as shown in the table.

In Table 2, X means no post-heat treatment, Y means 2 hours at 180°C as post-heat treatment, and Z means 15 minutes at 230°C as post-heat treatment. The cases in which the following conditions are adopted are shown in each case.

Photocuring performance test - (2) The heat-resistant photosensitive material described above was diluted with acetone, and this was coated on an aluminum plate to a thickness of 1 to 2 μm using a spinner. A test pattern was placed on this and ultraviolet rays were irradiated. and photocured.

Next, the film was developed in tetrahydrofuran to form a predetermined pattern, and then post-heated at 230°C for 15 minutes.

The obtained image characteristics are as shown below, and it was confirmed that it can be suitably used as a heat-resistant photoresist.

Number of photosensitive steps: 9 steps (using a 15-step step tablet) Resolution: 500 lines/line Changes due to developing chemicals: No thickening or expansion of the image was observed.

Example 2 In the esterification reaction of imide acid, fumaric acid, and ethylene glycol in Example 1, the number of moles of imide acid per mole of fumaric acid was set to 0.111 mole (AI) and 0.333 mole (/V)2. ) Two types of heat-resistant photosensitive materials of the present invention were prepared in exactly the same manner as in Example 1, except that the materials were changed to (2).

Comparative Example 1 In the esterification reaction of imide acid, fumaric acid, and ethylene glycol in Example 1, the number of moles of imide acid per mole of fumaric acid was 0.05 mole (/163) and 0.43 mole (4). Two types of heat-resistant photosensitive materials different from the present invention were prepared in exactly the same manner as in Example 1, except for the following.

As a result of conducting the above-mentioned storage stability test on the four types of heat-resistant photosensitive materials of Example 2 and Comparative Example 1, Example 2
No. /161,2 and No. 4 of Comparative Example 1 did not gel even after 30 days, and no change in properties was observed visually.

On the other hand, in Comparative Example 1, a gelatinized product began to form at the lower part of the second pewter and gelled at the fifth pewter.

Next, the four types of heat-resistant photosensitive materials mentioned above were photocured according to the above-mentioned photocuring performance test-(1).
The results of examining various properties similar to those described above for those subjected to post-heat treatment at 0°C for 15 minutes are as shown in Tables 3 and 4 below.

Note that Table 3 also lists the film properties before photocuring.

(To) /161 of Example 2 and A63 of Comparative Example 1 have a surface tank -i=, b, and the film is beautiful. Example 20A2 has no surface tank but has a beautiful film. A4 of Comparative Example 1 is a surface tank. There is no oxidation and the film is cloudy.

Comparative Example 2 In addition to the heat-resistant photosensitive material in Example 1, 1,1-bis(tertiary-butylperoxy) was added as a thermosetting catalyst.
When a storage stability test similar to the above was conducted on a product containing 2 parts by weight of 3,3,5-trimethylcyclohexane, it gelled after two days.

From this, it has been found that when using such a catalyst, an appropriate stabilizer must be used in combination.

Claims (1)

[Claims] 1 A tribasic acid in which the acid component that forms a chain ester bond with glycol has one photopolymerizable carbon-carbon double bond in the molecule, and 0.1 to 0. It consists of a tribasic acid containing an imide bond in the molecule represented by the following general formula in which the ratio is 35 moles; It has a free hydroxyl or carboxyl group at the end, is liquid or semi-solid at room temperature, has a hydroxyl value of 0.2 to 1.5 mmIJ equivalent/g, and an acid value of 1. The main ingredients are an unsaturated esterimide compound having an OmiIJ equivalent/g or less, and a photosensitizer in a blending ratio of 5.0 parts by weight per 100 parts by weight of this compound. A heat-resistant photosensitive material with excellent storage stability.