A device for coating strip-shaped substrates with parylene films
Patent Information
- Application Number
- JP2024535853
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2021-12-17
- Filing Date
- 2022-10-14
- Publication Date
- 2025-06-23
AI Technical Summary
Existing coating technologies for strip-shaped substrates using parylene film result in unwanted coating on both sides of the substrate and on unprotected surfaces within the working chamber, making them unsuitable for applications where selective coating is required.
A device comprising a feed-out and take-up roller system with a treatment roller, a first and second housing, and a pumping mechanism to create a controlled pressure differential, allowing selective coating of one side of the strip-shaped substrate while preventing deposition on the other side and inner chamber surfaces.
Enables efficient roll-to-roll coating of strip-shaped substrates with parylene film, minimizing unwanted coating on the back side and inner chamber surfaces, thus ensuring selective and controlled application.
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Abstract
Description
[Technical field]
[0001] The present invention relates to an apparatus for coating a strip-shaped substrate with a parylene film in a working chamber.
[0002] Parylene is the name of a family of polymers that can be formulated in a variety of ways that excel, for example, in good barrier properties, high chemical resistance and / or low coefficient of friction, so that parylene films are also often used as coatings, for example in medical technology, electronics or aerospace-based objects.
[0003] Parylene films are generally formed on the surface of a substrate by chemical vapor deposition. In this process, a solid, powdery or granular raw material called a dimer is first heated under vacuum conditions and sublimated into a gas. The gas then undergoes thermal decomposition, which results in cleavage into reactive monomer components. Finally, the monomer components are often deposited on the substrate at room temperature. Such a procedure is described, for example, in U.S. Pat. No. 8,889,224.
[0004] The deposition of parylene films on substrates has been established, for example, in so-called batch systems, as shown, for example, in WO 2007 / 003489. In this case, at least one substrate to be coated is introduced into a working chamber, the working chamber is closed, and at least one monomer-containing gas is flowed into the working chamber, which gas is deposited on the surface of the substrate by polymerization. After deposition, the working chamber is vented and the at least one substrate is removed from the working chamber. The device known from WO 2007 / 003489 may also have a cold trap, by means of which unreacted monomer molecules still present in the working chamber or in the gas outlet can be separated off before venting the working chamber after deposition. A disadvantage of coating substrates by chemical vapor deposition in general, and also of the above-mentioned procedure for depositing parylene films, is that the monomers flowed into the working chamber are deposited not only on the substrate, but also on all other unprotected surfaces in the working chamber.
[0005] The above-mentioned apparatus is also not suitable for coating strip-shaped substrates because, in addition to other technical problems, such as maintaining a vacuum when guiding a strip-shaped substrate through the work chamber, when such a strip-shaped substrate is guided through the work chamber of known batch systems, the back side of the substrate also becomes coated with parylene, which is undesirable in most applications.
[0006] From DE 10 2010010819 A1, a device is known in which a gas containing a parylene monomer is prepared and guided through a nozzle. In this case, the parylene monomer is deposited on the surface of a substrate that is passed past the nozzle opening. Such a system is therefore also suitable for coating a strip of substrate that is passed past the nozzle opening. However, even in the case of such a device, the disadvantage remains that parylene is also deposited on all other unprotected surfaces in the working chamber, and thus also on the back side of the substrate to be coated, unless protective measures are provided against this.
[0007] The technical problem underlying the present invention is therefore to provide an apparatus for coating a strip-shaped substrate with a parylene film, which overcomes the drawbacks of the prior art, in particular an apparatus according to the present invention which allows coating of a strip-shaped substrate in a work chamber in a roll-to-roll manner, while protecting the inner walls of the work chamber and the surfaces of the strip-shaped substrate that should not be coated from being coated with parylene.
[0008] This technical problem is solved by the subject matter with the features of claim 1. Further advantageous configurations of the invention are described in the dependent claims.
[0009] The apparatus according to the present invention for coating a strip-shaped substrate with a parylene film in a working chamber first includes a pay-out roller for paying out the strip-shaped substrate, a take-up roller for winding up the strip-shaped substrate after the coating process, and a treatment roller around which the strip-shaped substrate is partially wound and which can guide the strip-shaped substrate past the side of a coating zone. According to the invention, such an apparatus further comprises a first housing surrounding the coating zone and having a first opening directed towards the substrate, the first opening being surrounded by a first opening edge, a second housing having a second opening directed towards the substrate, the second opening being surrounded by a second opening edge and the second housing surrounding the first housing, thereby defining a volume between the first and second housings, at least one inlet extending through the wall of the first housing and capable of introducing at least one monomer-containing gas for depositing a parylene film into the coating zone, and at least one pump device capable of creating a negative pressure in the volume between the first and second housings, where monomer-containing gas means any gas containing monomer molecules known from the prior art that is suitable for depositing parylene films by chemical vapor deposition.
[0010] The invention will now be described in more detail with reference to one embodiment. [Brief description of the drawings]
[0011] [Figure 1] 1 is a schematic diagram showing an apparatus according to the present invention;
[0012] The device according to the invention shown in FIG. 1 has a working chamber 1 in which the substrate strip 2 to be coated is first wound around a pay-off roller 3. The substrate strip 2 is preferably coated on one side with a parylene film. For this purpose, the substrate strip is paid off from the pay-off roller 3 and guided through a treatment roller 4 in such a way that it is partially wrapped around the treatment roller 4, which guides the substrate strip 2 past a coating zone 5. After the coating process, the substrate strip 2 is wound up on a take-up roller 6. The device according to the invention may also have one or more deflecting rollers with which the substrate strip 2 can be guided through the working chamber 1 and / or past one or more further coating stations which may be arranged upstream and / or downstream of the coating zone 5.
[0013] An intermediate wall 7 separates the interior of the working chamber 1 into a winding chamber 8, in which atmospheric conditions may be formed, for example, and a treatment chamber 9, in which a pressure of more than 10 Pa is set, with the unwinding roller 3 and the winding roller 6 being located in the winding chamber 8 and the coating zone 5 being formed in the treatment chamber 9. The treatment roller 4 extends both into the winding chamber 8 and into the treatment chamber 9. For an efficient deposition, it is advantageous if the substrate is not heated too strongly during the parylene deposition. Therefore, in one embodiment of the invention, the treatment roller 4 is formed as a cooling roll or cooling roller and is dimensioned with respect to its cooling parameters in such a way that the substrate 2 is not heated to a temperature above 45° C. during the parylene deposition.
[0014] A first housing 10 arranged in the treatment chamber 9 and surrounding the coating zone 5 has a first opening directed toward the portion of the substrate 2 that is partially wrapped around the treatment roller 4, where the first opening is surrounded and thus defined by a first opening edge 11 of the first housing 10.
[0015] The device according to the present invention shown in FIG. 1 further comprises a second housing 12, which likewise has a second opening directed towards the part of the substrate 2 that is partially wrapped around the processing roller 4, in which case the second opening is surrounded, and thus also defined, by a second opening edge 13 of the second housing 12, in which case the second housing 12 surrounds the first housing 10, whereby the second housing 12 defines a volume 14 between the first housing 10 and the second housing 12.
[0016] The device according to the invention may further comprise a device for supplying at least one monomer for depositing the parylene film, as known from the prior art. The device according to the invention shown in FIG. 1 comprises for this purpose a vaporizer device 15, into which a powdered or granular dimer 16 is introduced as parylene raw material and heated at a temperature above 80° C. at a pressure below 10 Pa, where it is sublimated into a gas. This gas is fed to a pyrolysis device 17, where it is cleaved into monomers at a pressure below 10 Pa and a temperature above 550° C. These monomers are also introduced into the coating zone 5 via at least one inlet 18 extending through the wall of the second housing 12 and through the wall of the first housing 10, so that a pressure of less than 10 Pa is created in the first housing 10. At these pressure ratios, the monomer molecules in the coating zone 5 are polymerized to deposit a film on the side of the substrate 2 facing away from the treatment roller 4. This side of the strip-shaped substrate 2 is hereinafter also referred to as the front side of the substrate 2, whereas the side of the strip-shaped substrate 2 that faces the treatment roller 4 and is in contact with the treatment roller 4 is also referred to as the back side of the substrate 2.
[0017] 1, only one vaporizer device 15 is shown. Alternatively, the apparatus according to the invention may comprise a number of vaporizer devices 15, which are operated, for example, in parallel, such that a continuous supply of monomer-containing gas into the coating zone 5 is ensured.
[0018] As a further component of the device according to the invention, a pumping device 19 is shown in FIG. 1, by means of which a negative pressure can be created in the volume 14 between the first housing 10 and the second housing 12. In this case, the pumping device 19 is dimensioned in such a way that a pressure corresponding to at most 80% of the pressure set in the first housing 10 can be set by the pumping device 19. In a preferred embodiment, a pressure corresponding to 70% to 80% of the pressure in the first housing 10 can be generated by the pumping device 19 in the volume 14. In the example described, a pressure of less than 8 Pa is set in the volume 14. Thus, monomer molecules that are not deposited on the substrate 2 in the coating zone 5 but flow into the volume 14 through the gap between the substrate 2 and the first opening edge 11 are pumped out of the volume 14 by the pumping device 19. By the pumping device 19, it can be ensured that no or only negligibly small amounts of monomer molecules flow into the space outside the second housing 12 inside the treatment chamber 9 and do not form undesirable harmful deposits there.
[0019] In order, on the one hand, to maintain the abovementioned pressure ratio and, on the other hand, to ensure that a minimum of monomer molecules flow into the volume 14 or into the space outside the second housing 12 inside the treatment chamber 9, it is advantageous to make the distance between the substrate 2 and the first opening edge 11 as well as the distance between the substrate 2 and the second opening edge 13 as small as possible. Thus, in one further preferred embodiment of the invention, the first opening edge 11 of the first housing 10 and the second opening edge 13 of the second housing 12 are each spaced apart from the substrate 2 by a maximum distance of 3 mm.
[0020] In one alternative embodiment, the opening of the at least one inlet 18 is spaced from the substrate by at least 20 mm, which ensures sufficient distribution of the monomer-containing gas in the coating zone 5 for uniformly coating the substrate 2. To assist the distribution of the monomer-containing gas in the coating zone 5, at least one impingement metal sheet may additionally be arranged in front of the opening of the at least one inlet 18, which may be oriented, for example, such that the directional jet of the monomer-containing gas entering the coating zone 5 corresponds to a normal to the surface of the impingement metal sheet. In this case, the distance of the impingement metal sheet to the opening of the at least one inlet 18 may be, for example, 5 mm to 15 mm.
[0021] In order to protect the pumping device 19 against deposition of monomer on the walls inside the pumping device 19 and thus damaging it, it is advantageous if at least one cold trap 20 is further arranged in the flow path between the volume 14 and the pumping device 19, by means of which condensable components of the gas discharged from the volume 14 are filtered out before the discharged gas reaches the pumping device 19. In such cold traps 20 known from the prior art, a temperature of preferably below -40°C is set.
[0022] As another optional element, the device according to the invention may have at least one heating element capable of heating the first housing 10 and / or the second housing 12 to a temperature above 45° C. This again reduces the possibility of an undesirable harmful coating of the first housing 10 or the second housing 12. The at least one heating element may be configured, for example, as a resistive heating element, which is attached to the first housing 10 or the second housing 12 and generates heat upon the passage of an electric current therethrough.
[0023] In the embodiment shown in FIG. 1, it has been explained that the working chamber 1 has an intermediate wall 7, which divides the working chamber 1 into a winding chamber 8 and a treatment chamber 9. However, the intermediate wall 7 is an optional element of the invention. It is only essential for the invention that the pressure outside the second housing 12 is higher than the pressure in the volume 14. In an alternative embodiment, the working chamber 1 does not have an intermediate wall 7, so that the same pressure ratio prevails in the working chamber 1 throughout the area outside the second housing 12. However, this has the disadvantage that a larger or more pumping device is required for the area outside the second housing 12, which must maintain the required pressure ratio outside the second housing 12 when a negative pressure is to be generated outside the housing 12.
[0024] In principle, the parylene film can also be deposited on the strip-shaped substrate 2 in the working chamber 1 if the working chamber 1 does not have a second housing 12 and thus does not have an isolated volume 14 in terms of the pressure ratio. However, the disadvantage of such an arrangement is that all surfaces remaining in the working chamber 1 and outside the first housing 10 would be coated with an undesirable harmful coating and, if a negative pressure is to be created in the area outside the first housing 10, then larger or more pumping devices would still be required to maintain the required pressure ratio outside the first housing 10.
[0025] As mentioned above, the device according to the invention is also suitable for depositing a parylene film on a strip-shaped substrate in a roll-to-roll process. Since the strip-shaped substrate is in contact with the treatment roller on its back side during the coating process, there is no risk of deposition of parylene particles on the back side of the substrate. Furthermore, the pressure stage system formed in the treatment chamber by the first housing and the second housing prevents a parasitic parylene film from being deposited on the inner walls of the working chamber or on the treatment means arranged in the working chamber.
Claims
1. An apparatus for coating a strip-shaped substrate (2) with a parylene film in a working chamber (1), a) a pay-off roller (3) for feeding out the strip-shaped substrate (2), b) a take-up roller (6) for winding up the strip-shaped substrate (2) after the coating process, c) a processing roller (4) around which the strip-shaped substrate (2) is partially wound and which can guide the strip-shaped substrate (2) to pass by the coating zone (5), d) a first housing (10) surrounding the coating zone (5) and having a first opening directed towards the substrate (2), the first opening being surrounded by a first opening edge (11), the first housing (10), e) a second housing (12) having a second opening directed towards the substrate (2), the second opening being surrounded by a second opening edge (13), the second housing (12) surrounding the first housing (10), whereby the second housing (12) defines a volume (14) between the first housing (10) and the second housing (12), the second housing (12), f) at least one inlet (18) extending through the wall of the first housing (10) and capable of introducing at least one monomer-containing gas for forming the parylene film into the coating zone (5), g) at least one pump device (19) capable of forming a negative pressure in the volume (14) between the first housing (10) and the second housing (12) An apparatus comprising.
2. The apparatus according to claim 1, wherein the first opening edge (11) of the first housing (10) and the second opening edge (13) of the second housing (12) are each spaced apart from the substrate (2) by a maximum dimension of 3 mm.
3. The device according to claim 1 or 2, wherein the opening of the at least one inlet portion (18) is spaced apart from the base material (2) by at least 20 mm.
4. The device according to claim 1 or 2, wherein the working chamber (1) has a processing chamber (9) in which the coating zone (5) is formed inside.
5. The device according to claim 4, wherein a pressure exceeding 10 Pa is set in the processing chamber (9).
6. The device according to claim 1 or 2, wherein a pressure less than 10 Pa is set in the first housing (10).
7. The device according to claim 1 or 2, wherein a pressure corresponding to at most 80% of the pressure set in the first housing (10) is set in the volume (14) between the first housing (10) and the second housing (12).
8. The device according to claim 1 or 2, wherein at least one cooling trap (20) is arranged in the flow path between the volume (14) and the at least one pump device (19).
9. The device according to claim 1 or 2, wherein the processing roller (4) is formed as a cooling roll or a cooling roller.
10. The device according to claim 1 or 2, wherein at least one heating member capable of heating the first housing (10) and / or the second housing (12) to a temperature exceeding 45°C is provided.