DE3018069A1 - METHOD FOR HARDENING A FILM OF POLYAMID ACID OR ITS SALTS, PRODUCT FROM A SUBSTRATE WITH POLYIMIDE IMAGE AREAS, AND LIGHT-SENSITIVE PRODUCT FROM A FILM OF POLYAMID ACID - Google Patents

Description

Minnesota Lining and Manufacturing Company, 3M Center, Saint Paul, Minnesota 55'33, U S A

Method for hardening a film of polyamic acid or its salt, product from a substrate with Pclyimid image areas. and photosensitive product from a film made of polyamic acid

The invention relates to film curing Polyamic acids and / or their salts, which may be photosensitized to form polyimides. In particular the invention relates to the use of ultraviolet radiation for curing films made of polyamic acids and / or their salts and the light sensitization of such acids or salts using a photoinitiator.

As a rule, polyimides are formed by a condensation polymerisation reaction between organic diamines and Tetracarboxylic acid dianhydrides and are characterized by pronounced high temperature and dielectric properties the end. Because of the properties of polyimides, they have found widespread use in many fields.

Current practice in the art is to use polyimide films even dull polyamic acid, the precursor of polyimides, to buy in a liquid and pourable form. The polyamic acid can, once poured and

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The solvent is removed at elevated temperatures be softened or irrationalized, a.h. into the polyamide form be transferred. This hardening temperature is in Jer Order of magnitude of °

The problem with this practice arises from the fact that the number of substrates required for application of a curable Polyamic acid or its salt is available, is limited, d.n. such substrates must be their Weser, after being temperature resistant. However, in many cases it would be desirable to use substrates in conjunction with a polyimide to be used with the ncrr.sler. increased. Curing temperatures are not inherently heat stable to form the polyimide. So far it has not had a suitable solution to this problem given.

According to the invention it has now been found that ultraviolet radiation can be used advantageously for curing films of polyamic acids or their salts to form a polyimide. The condensation polymerisation uras that takes place during the hardening process can therefore be carried out at significantly lower temperatures than would normally be the case would consider necessary. This opens up the use of substrates, in conjunction with polyimides, which are excessive Temperatures do not have the normal stability or resistance.

In addition, films made of polyamic acids or their salts achieve the status of through the use of ultraviclet curing Products that can be defined according to the incidence of light, i.e. masking can be used selectively to avoid selected Areas of the films of polyamic acid or its salt in

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bilirvdßige '-'. way too harder ... what the removal of the not more struck by the light. Parts, i.e. again in pictorial catfish, is made possible. By incorporating a Photoinitiatcrs in the film will cause the curing reaction Pclyiraid significantly quick- "when exposed to actinic Radiation.

According to the invention there is provided a method for curing a film from Polyair.idsäure or its salt to the corresponding polyimide suggested that in the absence of external or external applied heat works and exposing at least one surface of that film to ultraviolet radiation for a sufficient time and at sufficient intensity to cure this film. In addition, a light sensitized person Proposed film of polyamic acid containing the acid or its salt and at least one photoinitiator contains. . ' ■

Since no high temperatures are necessary for hardening, can be a Yi ^ number of substrates with the obtained polyimide used that are not heat stable.

Selective curing in an imagewise fashion by a suitable master, followed by development, provides a photo-defined polyimide image.

Polyimides are made by making at least one organic Diarain's structural formula

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M * 22ϊ

wherein R- is a divalent Reo *; with at least two carbon atcr.er. and the two amino groups are each bonded to different carbon atoms of the divalent group having at least one ⁿ Tetracarbonsäuredia anhydride of the structural formula

0 0

^ R ' Il It O O

converts, j_ _n d _er R _e j_ _{n is a} tetravalent radical with at least two carbon atoms and no more than two carbonyl groups of the dianhydride are bonded to one (1) carbon atom of the tetravalent radical - the reaction initially forms a polyamic acid, which - if cured or further reacted at elevated temperatures - the corresponding polyimide is formed.

The preparation of polyamic acids is described in a number of U.S. Patents including U.S. Patents 3,179,6 "4, 31 79 63o, 31 79 631 and 3o 73 784.

It has now been found that effective curing of a polyamic acid can be performed using ultraviolet radiation. Under "ultraviolet radiation" means Actinic light along with its contained infrared energy is understood normally with ultraviolet Radiation is connected. This infrared energy disturbs the The hardening process is not, in fact, an aid. However, there is no need for external action of heat to achieve hardening.

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The polyanic acid can simply, in solvents such as N-methylpyrroxides, dimethylacetamide or dimethylformamide, be dissolved to a coating or application solution to obtain. Polyamic acid concentrations of about 1 to about 30 weight percent are satisfactory, but the only limitation is on reading concentration from the increased solution viscosity and the occurring Application problems result. About 15 to about 2o wt% represent the optimum for coating applications and are therefore preferred.

The dry film thickness of the polyamic acid or polyamic acid salt is related solely by practical considerations

achtrfiQllch I _au f ^ ie tTltraviolet exposure limited being about- / 25 / um changed I '

- · ■ '' * the maximum represent the exposure to ultraviolet radiation may of course also be on both sides of the film and run simultaneously, which one lettdurchdringung the Ultravi <and curing the polyamic acid or salt thereof can maximize polyimide....

The radiation intensity to effect the hardening can vary, with lower intensities requiring longer exposure times. The polyamic acid or its salt should exposure to radiation for a sufficient time, at sufficient intensity, sufficient to remove the acid or to harden their salt to polyimide form.

The term "photoinitiator" as used here corresponds to the usual usage of the word, i.e. he is a compound that, when exposed to actinic radiation, can undergo photolysis, which is then additional

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can initiate chemical reactions.

A wide variety of photoinitiators can be used with the Polyamic acid can be used, as illustrated by the examples. The photoinitiator concentration is not critical, and the examples do indeed clearly show that a very small initiator filtration is already very effective is with regard to a strengthening of the hardening reactions.

The invention is explained in greater detail below with reference to FIG non-limiting, but preferred examples, in the description of which all parts are parts by weight unless otherwise specifically stated.

Unless otherwise noted, the ultraviolet light source used in the examples was an ASHDEE UV 12/1 light source, manufactured by the Ashdee Division of George Koch and Sons, Inc. The unit has a single 3o, 48 cm long medium pressure mercury lamp of 2oo watts per 2.54 cm and an arc length of 3c, - + 8 cm.

While the samples were being exposed to ultraviolet radiation, the samples were attached to an aluminum plate, in order to have it in a firm hold during the exposure, then on the conveyor belt of the exposure unit at its entrance set, whereby the aluminum plate was then gripped at the output of the expander unit. Any such way through the unit is therefore referred to herein as "a passageway". To increase the quantity of radiation the products were made in several passes through the unit

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guided. If this is done so, it is dear to support a uniform exposure over the entire surface of the sample by the source during a pass in the longitudinal direction and during the subsequent passage at a right angle to pass through it. In all cases the conveyor speed was 1.83 meters per minute and the exposure time per pass under the exposure unit was approximately 1 second exposure to the most intense light. This exposure, i.e., a single pass through the unit at the specified rate, is a density of ο.22 watt-seconds per

2 "

cm equivalent, measured using an Ashdee Ultraviolet Power Density Meter, as it measures the 365 nm wavelength.

BeisDiel 1

A commercially available polyaraic acid, Pyre ML from DuPont, was used in this example. This acid is the reaction product of oxydianiline and pyromellitic dianhydride and is in solution as a suitable coating agent when it is sold.

This material was poured onto a copper foil weighing 28.35 g with a hook knife to a wet thickness of 150 μm to obtain, then was dried in air at 135 ° C ~ to to evaporate the solvent from the film.

The material was placed in the exposure unit, after which the degree of hardening or imidization thereof was determined with increasing amounts of radiation using infrared spectroscopy was controlled. Samples of the uncured film were made

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πι iuu 11 r 3.ν * ί ^ 1 r- ¹ ^ "^. ρ" S fr ~ r _ '* ^η ~ ν ~ * ~ ^ ~ _ η ^ ^ 3 ° ΐ ~ ^ s χ τ c ^ ~ e ⁿ t ir, Tab. I ur / en specified ..

The copper foil was then under Verv. ^r endur.g a conventional iron (III ιchloridlösung etched away, and the polyamic acid film was cleaned with deionized water.

The spectra of the uncured film show a predominant absorption band at the wavelength 3> 1 / µm the NH bond. As the imidization progresses, disappear the bands at 3.1 / µm and the characteristic imide bands at 5.6 and 13.8 / µm occur with higher absorption in appearance. This pQi * gressively reinforcing characteristic, when observing samples subjected to increasing passages of ultraviolet radiation for exposure, is expressed in Tab.

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Table I.

Analysis of the infrared spectra (values expressed in percent)

UV exposure

3.1 / µm peak 5.6 / µm peak 13.8 / µm peak

Permeability Absorption permeability Absorption permeability absorption

to

O OO CO

uncured

1 round

2 passes

3 passes

4 passes

5 passes

6 passes

7 passes

8 passes
1o passes
Thermosetting

12 11 16 69 63 68 7o 72 73 76 84

89 84 31 37 32 3o 28 27 24 16

32 26 19 19 1o

9 1o

1o 1o

8.5

68 74 81 81 9o 91 9o 91 9o 9o 91.5

24

23

21

16

16

17th

16, b

16

18th

17th

2o, 5

76

77

79

84

84

83

B 3, '>

84

82

83

79, b

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Example 2

To study the effect of curing a polyamic acid film by exposing to ultraviolet radiation through both sides of the film, as is the case with one

retrospectively I Pu _{m ο} } _ιηβ would be carrier, a sample of a polyami was changed |

'"* films, produced as in Example 1 on a copper foil

and dried at 149 ^° C., exposed to ultraviolet light. The copper backing of the film was then etched away, and the

the
Film exposed to ultraviolet light from / opposite side, i.e. the side adjacent to the copper. The infrared spectra of the samples exposed on both sides indicate faster curing or imidization than when only one side is exposed. The samples achieved essentially complete cure in two passes through the exposure unit, as can be seen in Table II.

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Table II

Analysis of the infrared spectra
(Value expressed in percent)

UV exposure 3.1 µm peak permeability absorption

5.6 µm peak permeability absorption

13.8. um-peak permeability absorption

Unhardened 26th 74 2o - 8o 27 73 I. O
co 1 round 92 8th 6th 94 18th 82 -P O 2 passes 93 7th 6th 94 17th 83 I. O 4 passes 93 7th 6th 94 16 84 C? ο > CD

OO O CD CO

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Example 3

Polyamic acid films dissolve further in alkaline Room temperature solutions, however, once hardened, alkalis show no significant attack more .

An alkaline solution was therefore prepared by dissolving sodium hydroxide (degree of analysis) in water for a portion of 5 g of solid sodium hydroxide in 95 ml of water, then the solution was mixed and allowed to stand at room temperature. After the solution was placed in a beaker equipped with a magnetic stirrer, samples of the polyaraic acid film were made suspended in such a way that the stirrer caused medium agitation.

Samples made according to Example 1 had a film peeled off without exposure to ultraviolet radiation in 1 min completely in the alkaline solution. After a single pass through the exposure unit, some Areas of the sample attacked after 2 minutes, indicating uneven exposure across the surface area of the Films existed. After 2 passes, partial attack in the alkaline solution was only observed after 5 minutes; the The same results were shown after 3 passes through the exposure unit. With 4 passes through the unit, was no visible attack on the imidized film after 6 minutes immersion in the alkaline solution detectable.

Example 4

Example 1 was repeated, with the modification that other carrier materials than copper foil were used as coating substrates were used. In all cases the degree of imidi-

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"ization or hardening tested using the above Example described alkali solubility tests. The following underlay materials were used: paper, polyester'f ilm, aluminum, stainless steel, epoxy fiberglass material for Control panels, solder and silicon wafers. In all cases the polyamic acid was found on these various substrates hardened.

Example 5

In order to evaluate the curability of other polyamic acids by exposure to ultraviolet radiation, "various Polyamic acids made using combinations of dianhydrides and diamines.

In each case, the diamine was in N-methylpyrrolidone in one Wide neck bottle loosened. The dianhydride was placed in a small polyethylene boat and floated on top of the diamine solution calmly. The bottle was capped with polyethylene film and shaken vigorously at once to mix in the dianhydride quickly. Generally it was a mild exotherm Reaction and an increase in the solution viscosity were observed. The mixture was placed on a shaker for further mixing set. In general, the reaction was complete in about 30 minutes and the solutions contained about 16% by weight of polyamic acid.

In this way, samples were prepared using benzophenone tetracarboxylic acid dianhydride together with hexane * diamine, methylenedianiline, m-phenylenediamine, oxydianiline and Methylenebiscyclohexylamine. In addition, pyromellitic dianhydride was used in connection with methylenedianiline, m-phenvlenediamine

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and methylenebiscyclohexylamine are used to make the corresponding To produce polyamic acids.

These acids were cast on copper foil and cured in an oven at 135 ° C, followed by exposure curing under the ultraviolet light source of Example 1. The progress of the curing cycle after exposure to ultraviolet Radiation was determined by the decrease in the 3.1 µm absorption peak followed in the infrared spectrum or by the alkali solubility test already described.

All samples prepared above showed a _n excellent cure after exposure to ultraviolet radiation.

Example 6

A polyamic acid was prepared as in Example 5 using benzophenone tetracarboxylic acid dianhydride and hexanediamine manufactured. The resulting polyamic acid was cast on copper foil and dried in an oven at 132 ° C for 15 minutes, to remove solvents. The thickness of the dried film on the copper foil was determined and found to be 2, 5 to 5, ο mm.

The sample was then exposed to ultraviolet rays using an original with patterns and various thereon Degrees of resolution exposed. About. The original was a quartz glass is set to hold it in a flat position. It was found that the exposure to ultraviolet Example 1 light source was satisfactory for 75 seconds and imparted photodefinability to the film. The on this Wise exposed sample showed a visible image of the exposure pattern. The exposed areas were intense yellow, the typical color of cured polyimide, while the unexposed areas remained unchanged. The sample was then

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developed with N-methylpyrrolidone and rinsed with water, thereby removing the unexposed areas. This was followed by air drying. The developed image showed excellent resolution.

Preferred polyamic acids include those in which ^it is producing uses the benzophenonetetracarboxylic with hexanediamine, oxydianiline and methylenebiscyclohexylamine, and the polyamide acids in Example 1. The benzophenonetetracarboxylic / hexanediamine combination is most preferred because it exhibits the best properties in terms of Photodefinierbarkeit . -

Example 7

lohtr & gltch changed

To g of a RC So ^ polyamic acid solution, commercially available from DuPont available, which according to the description of the manufacturer DuPont "is a solution of polyamic acid, which is through Reaction of aromatic diamines with aromatic dianhydrides, such as pyromellitic dianhydride ", were mixed with o, o75 g diethoxyacetophenone. The mixture was heated at 6o C for approximately 10 minutes to form a solution to support.

The clear solution obtained was applied to a 75 .mu.m thick polyester film to a wet film of 175 / To with a knife raised. The coating film was then placed in a compressed air oven of approximately 120 ° C for a period of 15 minutes to remove solvent from the film. It resulted a solvent free film approximately 25 µm thick.

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Immediately after removing the Frobe from the drying oven, the polyamic acid film was peeled off the polyester film and placed on a 3o, 48 cm 3o, 48 cm rigid board for ultraviolet curing.

Curing was accomplished by passing the panel and accompanying sample through the Ashdee ultraviolet apparatus.

To determine the degree of cure or crosslinking, i.e. the amount of conversion of polyamic acid to the polyimide state, became a Perkin Elmer infrared spectrophotometer Model 727B used. By comparing the samples to a fully cured and an uncured control sample The degree of cure was used for the test sample this infrared data spectrum is determined. A conversion of 95% was found.

Examples 8 to 48

Example 7 was repeated using different photoinitiators and concentration levels were applied. The results are shown in the table below.

Table III

Example weight percent used percent conversion no. Photoinitiator Photoinitiator conversion into PI

8th no (control) _ _ 2o 9 Diethoxyacetophenone 2.5 3o 1o Diethoxyacetophenone 6, o 5o 1 1 Diary1iodonium hexa-
fluorophosphate o, 75 9o * PI = Polyimide Continuation

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Table ΠΙ (continued)

example
No. weight percent used percent conversion
Photoinitiator Photoinitiator conversion in PI * 2.5 ] 45 continue. 12th Diaryliodonium hexa-
fluorophosphate 6, ο 9ο 13th Diaryliodonium hexa- "
fluorophosphate ο, 75 8ο 14th Triarylsulfonium
hexafluoroantimonate 2.5 '2ο 15th Triarylsulfonium
hexafluoroantimonate 6, ο 9ο 16 Triarylsulfonium
hexafluoroantiraonate ο, 75 7ο 17th 2,2-dimethoxy-2-phenyl-
acetophenone 2.5 2ο 18th 2,2-dimethoxy-2-phenyl-
acetophenone 6, ο 3ο 19th 2,2-dimethoxy-2-phenyl-
acetophenone ο, 75 8ο 2o 2-chlorothiaxanthone 2.5 4ο '' J. 21 2-chlorothiaxanthone 6, ο 5ο 22nd 2-chlorothiaxanthone ο, 75 8ο / 23 Methoxystyrylbistri-
chloromethyltriazine 2.5 5ο 24 Methoxystyryl bis-trichloro
raethyltriazine 6, ο 8ο ■; 25th Methoxystyrylbistri-
chloromethyltriazine ο, 75 7ο 26th Ultra yours 1oo (Sherwin
Williams) 2.5 6θ ": -" - " 27 Ultra yours 1oo (Sherwin
Williams) 6, ο 7ο 28 Ultra yours 2oo (Sherwin
Williams) ο, 75 4ο: 29 Benzoin 2.5 2ο ■ _! 3o Benzoin 6, ο 2ο ν 31 Benzoin ο, 75 5 ο '. \ 32 Benzoin Ethyl _S ter

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Table III (continued)

example
No. -% by weight used
Phctoinitiator - Photoinitiator 2.5 1, o Percent conversion
development in PI * 33 Benzoin ethyl ester 6, ο 1, o 3o 34 Benzoin ethyester o, 75 1, o 5o 35 Michler's ketone 2.5 1, o 2o 36 Michler's ketone 1, o - - 3o 37 Anthracene 1, o 5o 38 1-chloroanthraquinone 1.0 4o 39 Fluorescein 1, o 8o 4o Benzoin methyl ether 1, o 15th 41 Phenanthrenequinone 1, o 7o 42 p-benzoquinone Benzophenone and N-methyl-
diethanolamine (3/2) 1, o 7o 43 2-tert-butylanthra-
chinone 3o 44 Benzophenone 15th 45 2-naphthalenesulfonyl
chloride 3o 46 Benzil 6o 47 none (control sample) 45 48 15th

Examples 49 to 64

In order to determine the relationship between the degree of conversion or hardening of the polyamic acid to polyimide, based on the photoinitiator concentration, To determine, Examples 49 to 64 were carried out, wherein the procedure used with that of Example 7 was identical except for the photoinitiator concentration.

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Table IV O Percent conversion
ment in PI example
No. weight percent used
Photo initiator Photo initiator o, o5 2o 49 no (control) o, 1o 7o 5o Diethoxyacetophenone o, 2o 80 51 Diethoxyacetophenone o, 4o 80 52 Diethoxyacetophenone o, 8o 9o 53 Diethoxyacetophenone 1, 60 95 54 Diethoxyacetophenone 3.2o 80 55 Diethoxyacetophenone o, o5 85 56 Diethoxyacetophenone 0.10 95 57 Diphenyliodonium hexa-
fluorophosphate o, 2o 9o 58 Diphenyliodonium hexa-
fluorophosphate o, 4o 95 59 Diphenyliodonium hexa-
fluorophosphate 0.80 9o 6o Diphenyliodonium hexa-
fluorophosphate 1, 60 85 61 Diphenyliodonium hexa-
fluorophosphate 3.2o 95 62 Diphenyliodonium hexa-
fluorophosphate 6.4o 95 63 Diphenyliodonium hexa-
fluorophosphate 75 64 Diphenyliodonium hexa-
fluorophosphate

Examples 65-68

To compare the foregoing examples with the use of heat alone, i.e. without ultraviolet radiation when curing or crosslinking polyamic acid, the procedure of Example 7 was repeated except that thermal Heat was used as the curing agent instead of ultraviolet radiation. After curing for 15 min at 149 ° C,

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there was a zero percent conversion to Pciyiraid. At 2o4 ° C 80% conversion was observed during the same period of time, 90% conversion at 260 ° C for 15 minutes and at 3 ^ 3 C for 15 min / a 95% conversion to observe.

Examples 69 to 74

In order to demonstrate the effectiveness of incorporating a photoinitiator into the polyamic acid system, non-sensitized were made Polyamic acid films prepared according to Example 7 for comparison purposes. These films were unsensitized exposed to prolonged ultraviolet radiation as indicated in Tab. A comparison of Tab. V with the data of Tab »III - after which only a single pass of ultraviolet exposure was used - clearly shows that the effectiveness of the Addition of a photoinitiator to the polyamic acid system is considerable.

Table V

Example number d. Passes percent conversion

No. (a 2oo W / 2.54 cm- in polyimide

Lamp - 15.24 cm / min)

2o 4o 7o 9o 95

69 0 7o 1 71 2 72 4th 73 7th 74 1o

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Examples 75 to 84

Polyamic acids were made using benzophenone tetracarboxylic dianhydride / m-phenylenediamine (Examples 75-8o) and benzophenone tetracarboxylic dianhydride / oxydianiline (Examples 81-84). Example 7 was then repeated with with the exception that the conveying speed in the exposure unit was 3.05 meters per minute. The results are tabulated below.

Table VI

example
No. used photo
initiator and weight% Amount d.
UV curing Percent conversion
conversion to PI 75 no no UV 2o 76 no 1 round 3o 77 6 % methoxystyryl bis-
trichloromethyltriazine no UV 3o 78 6% methoxystyryl bis-
trichloroethyltriazine 1 round 65 79 6% triarylsulfonium
hexafluoroantimonate no UV 25 Λ 8o 6% - triarylsulfonium
hexafluoroantimonate 1 round 65 81 no no UV 1 ο 82 no 1 round 2o 83 o, 75% triarylsulfonium
hexafluoroantimonate no UV 15th 84 o, 75% triarylsulfonium
hexafluoroantimonate 1 round 4o. ■

Polyamic acid can be applied to substrates made with are unstable at elevated temperatures, i.e. paper, polyester, etc., and yet are effectively cured to the polyimide state.

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It was also found that the conversion of polyamic acid into a salt before curing, a product having the same functionality with respect to ultraviolet ray curing provides and can even offer additional benefits. If an appropriate salt is used, one observes greater latitude in exposure and development, i.e., greater exposure and development latitude possible. The time required for the formation of a hardened image is reduced and an increased image resolution is provided with the unexposed areas being removed more easily and without leaving a residue.

A polyamic acid can be converted into a salt by simply mixing it in a solvent with a base , preferably using an equivalent concentration of the base. When the obtained cured polyimide to be used in an electrical application, for example as a dielectric layer, it is preferred to use volatile non-metallic bases to form the salt.

Example 85

A polyamic acid was prepared as in Example 6, the resulting mixture containing 20% polyamic acid solids. 1.84 g of triethylamine were added to 20 g of the acid, after which the acid was converted into a salt.

The salt solution was drawn onto an aluminum foil and dried in an oven at 130 ° C. for 15 minutes to remove the solvent. The dried film was exposed through a photomask ^e quartz glass with ultraviolet radiation for 1 minute using a Model colite DMVLS Exponiereinheit.

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The imagewise exposed film was treated with N-methylpyrrolidone after which the unexposed areas of the film were removed. The obtained sample was rinsed with toluene and air dried. To ensure that the solvent had been completely removed and to drive off The film was heated at 340 ° C. for 3 minutes with the remaining triethylamine.

A polyimide image area with excellent resolution was produced.

Claims (1)

Claims . Process for hardening a film of a polyamic acid or its salt to form a corresponding polyimide, characterized in that this Curing is carried out in the absence of externally applied heat and exposing at least one surface this film "with ultraviolet radiation at sufficient intensity for a sufficient time to cure this movie includes. 2. The method according to claim 1, characterized in that this polyamic acid from the group of polyamic acids Basis of benzophenone tetracarboxylic acid dianhydride / hexanediamine, benzophenone tetracarboxylic acid dianhydride / oxydianiiine, Benzophenone tetracarbene dianhydride / methyienbiseyclohexylamine and pyrcmellitic dianhydride / jxydianiline is selected. 3- Method of curing a film of a polyamic acid or its salt on a carrier to form a corresponding polyimide, characterized in that da / l this curing is carried out in the absence of externally applied heat and exposing the surface to this Film with ultraviolet radiation. sufficient intensity for a time sufficient to cure this film ur.fanr. 030047/0894 BATH μ. -5: 4th traversing r. .-. oh a Jer claims 1 ei 3 3, thereby marked. that this Pclyamidsäjre film. selected is based on the Irupce of the p-Iyamic acid FilTse of rer.zrphenonterracarboxylic acid dianhydride / hexanediamine, Benzopnenone tetracarbic acid dianhydride / oxydianiline, benzophenone tetra ·? arbenic acid dianhydride / methy ler.b is cyclohexyl amine and pyrnellitic dianhydride / oxydiar.iline. Process for the formation of an image-wise differentiated Build-up from a polyimide image on a carrier that is connected to a polyamic acid or the salt of which is coated, characterized in that this Image is formed in the absence of externally supplied heat and the following steps are carried out: (a) Exposing this polyamic acid or its salt to ultraviolet radiation in an imagewise fashion for sufficient time at a sufficient intensity to allow this polyamic acid or its salt to reach the exposed Places to harden while the non-expanded areas remain uncured, and (b) Develop these unexposed areas with a suitable solvent. Method according to claim 5, characterized in that the polyamic acid used from the group of polyamic acids based on benzophenone tetracarboxylic acid dianhydride / Hexanediamine, benzophenone tetracarboxylic acid dianhydride / oxydianiline, Benzophenontetracarboxylic acid / methylenebiscyclohexylamine and pyromitic dianhydride / oxydianiline is selected. 7. Product made from a substrate with polyimide image areas thereon, characterized in that that these image areas after the process 030047/0894 BAD ORiC des Ar.scr-chs 5 have been formed. 8. Photosensitive product, marked by a film of polyanic acid, the at least one Contains photo initiator therein. 9. Photosensitive product according to claim 8, characterized characterized in that this product contains a substrate which on at least one surface with a Polyamic acid is coated, which has at least one photoinitiator contains. 030047/0894 BAD ORJG ^iMA! OAi