EP0208259B1 - Packaging for materials sensitive to humidity - Google Patents

Abstract

A package for photoresist material, particularly a dry resist, is substantially impermeable to water vapor, thereby preventing humidity-related effects which adversely influence the processability of the photoresist. The package can comprise a film tubing, the ends of which are closed by welding or gluing, into which a photoresist roll is placed. As the material for the film tubing, a composite material can be used which is formed of a polyester film as the support film, to which an aluminum foil is laminated or which is vacuum-metallized with aluminum and a polyethylene film laminated on top. A tinplate container can also be used as a package, the container being closed by soldering after placing the photoresist material inside the container. These packages generally have a permeability to water vapor of less than 0.01 gram of water vapor per square meter per day, at a humidity gradient of 97% and an ambient temperature of 23 DEG C.

Description

The invention relates to a packaging for dry resist material, which is wound on rolls or stacked in sheet form, according to the preamble of claim 1 (known from EP-A 52 560).

So-called dry resists are aqueous-alkaline or photoresists from three-layer systems that can be processed with organic solvents, in which the photopolymer layer is embedded between a carrier film and a protective film. A polyester film, such as polyethylene terephthalate, is often used as the carrier film, and a polyolefin film, such as e.g. Polyethylene, related.

For sales, shipping and storage, the photoresists are generally wound on rolls, wrapped in light-tight packaging films and placed in cardboard boxes. The material for the packaging films is often polyethylene, which is colored with soot. Square or rectangular discs are attached to the end faces of the winding cores of the rolls, which are intended to protect the rolls from mechanical damage during transport and handling.

The known packaging primarily serves to protect the photoresists from the undesired exposure to light, in particular ultraviolet radiation, from weather influences, from mechanical damage during transport and from contamination.

In practice, it has been found that photoresists packed in this way tend to stick to the front edges after longer transport routes and / or longer storage times, particularly pronounced on the front edges near the winding core of the roll. In these cases, the photoresist emerges in small amounts at the end edges of the roll and glues the individual layers of the winding together. Such bonds adversely affect the further processing of the dry resist, since when the photoresist is unwound, small resist particles are torn off the roll and can contaminate the plates, for example printing or printed circuit boards, onto which the photoresist is laminated. Such gluing of the front edges of photoresist rolls not only occurs as a result of long storage times, it was also found that the storage conditions as such also have a considerable influence on the processing properties of the photoresist. So it can happen that a photo resist roll stored for one year can still be processed perfectly, while another photo resist roll from the same batch, stored elsewhere under different storage conditions, has already become unusable for further processing after three months.

This different behavior of photoresist material, which comes from the same batch, clearly shows that the storage conditions and the mode of transport have a considerable influence on the further processing of the photoresist material. The gluing of the leading edges of the photoresist rolls, as closer investigations show, can be attributed to the flow of the photopolymer layer of the photoresist material.

The object of the invention is therefore to prevent the flow of stored dry resist material, regardless of the period between the production and processing of the dry resist material, the duration of storage and the storage conditions.

This object is achieved in that the material of the packaging has a water vapor permeability of less than 0.01 grams of water vapor per square meter and day, at a relative humidity of 97% and an ambient temperature of 23 _° C.

The further embodiment of the invention results from the features of claims 2 to 9.

The packaging according to the invention can of course also be used for dry resist material which is stacked in sheet form.

With the invention, the advantage is achieved that in the case of the absolutely moisture-impermeable packaged photoresist material, edge exits practically no longer occur, even if the photoresist material is stored for a very long time. “Absolutely impermeable to moisture” is to be understood here to mean a package whose permeability to the water vapor in the air is so small that it can no longer be detected with the most sensitive measuring devices currently available. The limit of detection is currently at about 0.001 g / m ² d. This result is very surprising, since the polyethylene films commonly used for packaging are generally considered to be impermeable to water vapor.

• Figuren 1 und 2 die Geschwindigkeit der Wasseraufnahme eines Fotoresists,
• Figur 3 die Viskosität zweier verschiedener Fotoresiste in Abhängigkeit von ihrem Wassergehalt,
• Figur 4 schematisch in perspektivischer Schnittansicht die Stirnkanten einer Fotoresistrolle, die in einer Verpackung nach der Erfindung längere Zeit gelagert ist,
• Figur 5 schematisch in perspektivischer Schnittansicht die Stirnkanten einer Fotoresistrolle, die herkömmlich verpackt gelagert ist, und
• Figur 6 einen Schnitt durch ein für die Verpackung verwendetes Folienschlauchmaterial.

The invention is explained in more detail below with reference to the drawings. Show it:

• Figures 1 and 2, the speed of water absorption of a photoresist,
• FIG. 3 the viscosity of two different photoresists depending on their water content,
• FIG. 4 schematically, in a perspective sectional view, the end edges of a photoresist roll, which is stored in a packaging according to the invention for a long time,
• Figure 5 shows schematically in a perspective sectional view the end edges of a photoresist roll, which is conventionally stored, and
• 6 shows a section through a film tube material used for the packaging.

The results of the tests carried out on photoresist materials, the evaluation of which led to the packaging according to the invention, are described with reference to FIGS. 1 to 4.

Systematic studies of the water absorption and the viscosity of negative photoresists have shown that the viscosity of the photoresists that are delivered in the dry state after production is reduced very sharply due to moisture absorption from the air by diffusion during storage. The photoresist, which becomes thin due to the reduction in viscosity, can then emerge from the end edges of the photoresist rollers under the influence of the winding tension. Two further effects increase the emergence of photoresist at the front edges due to the moisture absorption by the photoresist. This swells when the water is absorbed, and the swelling pressure presses out the thin liquid photoresist at the edges of the photopolymer layer. If the winding cores consist of water-absorbing materials, such as cardboard, they begin to swell as a result of the atmospheric moisture, which increases their pressing pressure and supports the effects listed above.

The rate at which water is absorbed by a photo resist from the air naturally depends on external circumstances. FIG. 1 shows the water absorption of a three-layer photoresist sample, in which the photoresist was exposed to atmospheric moisture without a carrier and cover film. The photoresist sample is first dried over phosphorus pentoxide and then exposed to an atmosphere with 53% relative humidity. At room temperature, the sample is saturated after 1.5 hours.

FIG. 2 shows the water absorption of a photoresist sample covered on both sides with foils, which, like the aforementioned photoresist sample, consists of three layers. This sample was first also dried over phosphorus pentoxide and then exposed to an atmosphere with 53% relative humidity. The equilibrium has not yet been reached after 20 hours.

For the course of the water absorption of a photoresist roller stored in the air, it follows from these investigations that moisture will penetrate from the front edges faster than through the layers of the photoresist material protected by foils.

FIG. 3 shows the viscosities of two different photoresist materials as a function of the water content of the photoresist materials. The water content of the individual photoresist is roughly proportional to the air humidity. The course of the viscosities shows that photoresists, which are manufactured largely dry and have a high initial viscosity, absorb water when stored in air, which generally always has a certain atmospheric humidity, and thus become thin, i.e. in other words, their viscosity decreases.

The respective ambient temperature has an influence on the viscosity of the photoresist in that it decreases with increasing temperature.

Water absorption causes swelling of the photoresists, which can lead to an increase in thickness and volume of up to 4.6% and 13.8%, respectively, when the relative humidity of the air is increased from 0% to 97%, at a room temperature of 23 _° C.

It follows from the above statements that the water absorption by the photoresist material, due to the relative humidity of the ambient air, favors the emergence of photoresist material at the front edges of rolls. For an ideal packaging it follows that it must be absolutely watertight so that the low moisture content of the material set during the production of photoresist material is preserved until consumption and also a temperature rise during storage does not allow the photoresist material to advertise too thinly. The packaging according to the invention, which reliably ensures the quality of the photoresist material over long periods of time, can be implemented in various ways.

As shown in FIG. 4 in the schematic and perspective sectional view, a photoresist roll 2 is enclosed by a packaging 1, which consists of a film tube made of water vapor-impermeable material. The film tube is welded or glued at both ends. At the ends, the winding core of the photoresist roll 2 is closed with end disks, which are not shown. The upper end edges of the roll roll of the photoresist roll 2 are free of photoresist material leaks. When packaging, it is irrelevant whether the photoresist roll 2 is welded directly into the packaging 1 from the film tube, or whether the photoresist roll 2 is first placed on the end disks and then packed. It is only assumed that there are no water vapor-emitting materials, such as cardboard winding cores, within the package 1, since these would of course restrict the effect of the water vapor-tight package 1.

The effect of the tight packaging can be further improved in that, immediately before the packaging 1 is sealed or glued, the air is sucked out of the interior of the film tube or replaced by dry air or a dry gas.

When packaging the photo roll 2 with a film tube, care must be taken to ensure that the film tube is not damaged. Small holes or cracks enable the passage of air, which always has a certain atmospheric humidity, through the packaging 1, in particular in the event of changes in temperature, so that its effect is partially canceled. To a certain extent, the water vapor introduced by the entering air can be controlled by a container 6, the content of which is a desiccant 10, in the case of damaged packaging 1. The container 6 can be arranged in the packaging 1 in various ways. Either the container 6 is packed with the photoresist roll 2, inserted into a loop or pocket provided on the inside of the packaging 1, or inserted into the inside of the winding core of the photoresist roll. The desiccant in the container 6 only offers protection in the event of minor damage to the packaging 1, but in no way can it replace the packaging 1 as such. For example, commercially available silica gel types are suitable as drying agents.

As a further packaging according to the invention for one or more photoresist rolls 2, a tinplate canister is provided, into which the photoresist rolls are soldered individually or in groups, so that no air humidity can penetrate into the interior of the packaging.

Fig. 5 shows schematically in perspective Sectional view of a photo resist roll 2, which was stored in a black colored polyethylene film tube 11 at 97% relative humidity for eleven days. After this storage, the photoresist roll 2 stored over saturated potassium sulfate solution to maintain 97% relative air humidity shows the schematically indicated photoresist outlets 5 on the front edges, caused by the entry of moist air through the polyethylene film tube 11 serving as packaging, the water vapor permeability of which is generally considerably greater than 1 g / m ² d at 85% relative humidity difference and 23 _° C ambient temperature.

A film material used for the packaging 1 is shown in section in FIG. 6. It is a polyester-aluminum composite made of a biaxially stretched polyester film 7 as a carrier film, such as a polyethylene terephthalate film (HOSTAPHAN _@ ) from Kalle Niederlassung der Hoechst AG, which is laminated with an aluminum film 8 or vapor-coated with aluminum and is laminated with a polyethylene film 9. The polyethylene film 9 can also be extrusion coated. The polyester film 7 has a thickness of approximately 12 ₁₁ m, the aluminum film 8 from 7 to 12 ₁₁ m and the polyethylene film 9 from 70 to 100 ₁₁ m. The first-mentioned material layer, namely the polyester film 7 of the composite, is always on the outside of the packaging 1; the last-mentioned layer is facing the packaged goods. The sealing temperature for the film composite is between 130 and 180 _° C. The water vapor permeability is less than 0.001 g / m2d and thus offers sufficient tightness for the storage of the photoresist rolls, even under very unfavorable conditions.

The comparative tests described in the following examples were carried out to check the effectiveness of the packaging in preventing photoresist leaks.

example 1

A 100 m photoresist roll with a width of 400 mm of the "Ozatec T 138 _@ " photoresist from Kalle Niederlassung of Hoechst AG was put into a cylindrical tinplate container immediately after production, this was closed with a lid and then soldered on. A second roll of photoresist made of the same photoresist material was wrapped in a black colored film made of polyethylene. The ends of the film were loosely inserted into the hollow winding core of the photoresist roll. The two differently packaged photoresist rolls were stored in a plastic container, lying on a wire shelf, at an ambient temperature of 23 _° C for four weeks. During this time, 2 cm of water stood on the bottom of the plastic container, so that there was always a very high level of air humidity inside the plastic container. Both rolls of photo resist were removed after four weeks of storage, opened and checked visually. The photoresist roll packed in the tinplate container showed no change at the front edges after this storage, which were completely flawless and free of photoresist escapes.

The photoresist roll wrapped in the polyethylene film, on the other hand, showed strong leakage of photoresist material at the front edges and sticking of these exits, which experience has shown to greatly impair the processability of the photoresist material.

Example 2

The procedure was the same as in Example 1, instead of the tinplate canister, a film tube made of the above-described polylester-aluminum composite from Kalle Niederlassung of Hoechst AG was used, and the free tube ends were sealed immediately after the photo-roll was packed. After four weeks of storage, the photoresist roll packed in this way showed no changes on the front edges that were completely flawless. In this respect, this result is comparable to the result of the packaging of the photoresist roll in a soldered tinplate canister according to Example 1 without any restriction.

The photoresist roll loosely packaged in the polyethylene film, on the other hand, showed, as in Example 1, a large amount of photoresist at the front edges and corresponding sticking of the photoresist outlets.

Example 3

The test arrangement was the same as in Example 1. A photoresist roll of the same type as in Example 1 was packed in a film tube made of polyester-aluminum composite and welded to it. The film tube was deliberately damaged by repeated bending, only the aluminum film was broken, but not the carrier film and the laminated polyethylene film, as far as this could be assessed visually. A second roll of photoresist of the same type was sealed in a film tube which was treated in the manner described above. A bag of 100 g of granular silica gel was packed with this photo resist roll. Both packaged photoresist rolls were then stored for four weeks, as in Example 1, over water. The inspection of the photoresist rolls after this time showed that there was a slight edge leakage at the front edge of the photoresist roll when packaging without desiccant, while the photoresist roll packed with desiccant was in perfect condition.

Claims (7)

1. Packaged photoresist material wound up into rolls or stacked in the form of sheets, with a virtually water vapor-impermeable, sealed package characterized in that the packaging material has a permeability to water vapor of less than 0.01 gram of water vapor per square meter and day, at a relative air humidity of 97 % and an ambient temperature of 23 _°C.

2. The packaged photoresist material as claimed in claim 1, wherein the permeability to water vapor is less than 0.001 gram of water vapor per square meter and day.

3. The packaged photoresist material as claimed in claim 1, wherein the package (1) comprises a film tubing which is closed at the two ends thereof and comprises a composite material formed of a polyester film (7) which is vacuum-metallized with aluminum or laminated with an aluminum foil (8), and a polyethylene film (9) applied by laminating or extrusion-coating.

4. The packaged photoresist material as claimed in claim 3, wherein the interior of the film tubing is filled with dry air or a dry gas before the ends of the film tubing are hermetically sealed by glueing or welding.

5. The packaged photoresist material as claimed in claim 3, wherein the air in the interior of the film tubing is exhausted before the ends of the film tubing are hermetically sealed by glueing or welding.

6. The packaged photoresist material as claimed in claim 1 or claim 2, wherein the package comprises a tinplate container which has the shape of a cylinder or a rectangular parallelipiped, the ends of which are closed by soldering.

7. The packaged photoresist material as claimed in claim 3, wherein a desiccant (10) packaged in a receptacle (6) is present in the interior of the package (1).

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