Method for bonding substrates containing polymers on surfaces thereof, bonding apparatus, and laminate

Abstract

Provided are: a method for bonding substrates containing polymers on the surfaces thereof; a bonding apparatus; and a laminate, applicable to high-frequency circuits in which substrates containing polymers on the surfaces thereof are firmly bonded with each other at low temperatures. The method for bonding substrates containing polymers on the surfaces thereof comprises: forming a precursor layer by radiating a first ultraviolet ray in a state in which a certain concentration of a crosslinking substance is present on one or both of the bonding surface of a first substrate 61 and the bonding surface of a second substrate 62; and bringing the first substrate and the second substrate into contact with each other to bond the first substrate 61 and the second substrate 62 via the precursor layer.

Description

Method and apparatus for bonding substrates containing polymer on their surfaces, and laminate

[0001] The present invention relates to a method for bonding substrates containing a polymer on the surface, a bonding apparatus, and a laminate.

[0002] Polyimide (PI) films are used as insulating materials for flexible printed circuit boards (FPCs) due to their excellent heat resistance, flexibility, and electrical insulation. Flexible copper-clad laminates (FCCLs) are used to manufacture flexible printed circuit boards, and sputtering, a dry method, is used as a metallization method for the polyimide surface in flexible printed circuit boards that require fine circuit formation.

[0003] As mobile information terminals, such as smartphones, become smaller and more powerful, there is a strong demand for lighter, thinner, shorter, and smaller flexible printed wiring boards (FPCs), which can be used to form finer patterns and at lower costs. In particular, insulating materials used as the base material for FPCs are required to be compatible with high-frequency circuits. However, materials with good properties for high-frequency circuits are generally expensive, resulting in high manufacturing costs. Therefore, the formation of laminates in which conventional materials are bonded with materials that have good properties for high-frequency circuits has been considered. Therefore, there is a demand for a method to bond these materials firmly and cost-effectively.

[0004] Meanwhile, a technology using organic adhesives has been developed to bond and laminate polymer films at low temperatures (Patent Document 1). When using organic adhesives, in special environments such as vacuums, the organic solvent evaporates from the adhesive layer of the final product over time, which can reduce the mechanical strength of the bonded portion. Furthermore, defects such as bubbles can occur, reducing yields and increasing final costs.

[0005] Japanese Patent Application Laid-Open No. 2008-150550

[0006] In order to solve the above-mentioned problems, an object of the present invention is to provide a method for joining substrates containing a polymer on their surfaces, a joining device, and a laminate that can be used in high-frequency circuits for firmly joining substrates containing a polymer on their surfaces at low temperatures.

[0007] To solve the above-mentioned problems, the present invention employs the following means. Specifically, the method of bonding a substrate containing a polymer to a surface of the present invention includes irradiating a bonding surface of a first substrate with a first ultraviolet ray in a state in which a certain concentration of crosslinking substance is present on either or both of the bonding surfaces of a second substrate to form a precursor layer, and abutting the first substrate with the second substrate to bond the first substrate with the second substrate via the precursor layer. According to this invention, the precursor layer is formed by irradiating a bonding surface of a first substrate with a first ultraviolet ray in a state in which a certain concentration of crosslinking substance is present on either or both of the bonding surfaces of the first substrate with the second substrate, and thus the first substrate can be firmly bonded to the second substrate by abutting the first substrate with the second substrate via the precursor layer.

[0008] Another aspect of the present invention relates to a method for bonding a polymer-containing substrate to a surface, which includes forming an insulating film on one or both of the bonding surfaces of the first substrate and the second substrate, irradiating one or both of the bonding surfaces of the first substrate and the second substrate with first ultraviolet light in a state where a certain concentration of cross-linking substance is present on either or both of the bonding surfaces of the first substrate and the second substrate to form a precursor layer, and contacting the first substrate with the second substrate to bond the first substrate with the second substrate via the precursor layer. According to this invention, an insulating film is formed on one or both of the bonding surfaces of the first substrate and the second substrate, and further a precursor layer is formed on one or both of the bonding surfaces of the first substrate and the second substrate. Therefore, by contacting the first substrate with the second substrate via the precursor layer, the first substrate and the second substrate can be more firmly bonded.

[0009] In one aspect of the present invention, the method includes irradiating one or both of the bonding surface of the first substrate and the bonding surface of the second substrate with second ultraviolet light before forming the precursor layer. In this one aspect, since the bonding surface of the first substrate and the bonding surface of the second substrate are irradiated with second ultraviolet light before forming the precursor layer, the surfaces on which the precursor layer is to be formed can be cleaned.

[0010] In one aspect of the present invention, the method includes irradiating one or both of the bonding surfaces of the first and second substrates with third ultraviolet light before forming the insulating film. In this aspect, since the bonding surfaces of the first and second substrates are irradiated with third ultraviolet light before forming the insulating film, the surfaces on which the insulating film is to be formed can be cleaned.

[0011] In one aspect of the present invention, the formation of the precursor layer and the bonding are performed in an environment in which the oxygen concentration and the moisture concentration are controlled. In this aspect, the formation of the precursor layer and the bonding are performed in an environment in which the oxygen concentration and the moisture concentration are controlled, so that an environment suitable for each step can be prepared.

[0012] In one aspect of the present invention, the control of the oxygen concentration and the moisture concentration is carried out in a vacuum or an inert gas atmosphere. In this aspect, the control of the oxygen concentration and the moisture concentration is carried out in a vacuum or an inert gas atmosphere, so that an appropriate environment for controlling the oxygen concentration and the moisture concentration can be created.

[0013] In one aspect of the present invention, the first and second substrates are any of polymer films of LCP (liquid crystal polymer), PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer), PTFE (polytetrafluoroethylene), COP (cycloolefin polymer), PPS (polyphenylene sulfide), PEEK (polyether ether ketone), PI-based (including PI (polyimide) and MPI (modified polyimide)), PPE-based (including PPE (polyphenylene ether) and mPPE (modified polyphenylene ether)), graphite sheets, or laminates of combinations thereof. In this aspect, an appropriate material can be selected as the substrate material.

[0014] In one aspect of the present invention, the first and second substrates are substrates having a circuit on which an organic material is coated. In this aspect, even if the substrate has a circuit, a laminate can be formed through the coated organic material in the same manner as described above.

[0015] In one aspect of the present invention, the first and second substrates are substrates including a conductive region on at least a portion of their surface. In this aspect, since the substrates including a conductive region on at least a portion of their surface are joined, a laminate can be formed in which the circuits of the substrates are connected to each other.

[0016] In one aspect of the present invention, the cross-linking substance is any one or any combination selected from the group consisting of ammonia, primary alcohols, and secondary alcohols. In this aspect, an appropriate substance can be selected as the cross-linking substance.

[0017] In one aspect of the present invention, the first ultraviolet ray, the second ultraviolet ray, and the third ultraviolet ray have a dominant wavelength of any one of 156 nm, 172 nm, 185 nm, 206 nm, 222 nm, 254 nm, 283 nm, and 308 nm, or any combination thereof. In this aspect, the first ultraviolet ray, the second ultraviolet ray, and the third ultraviolet ray can be selected to have an appropriate dominant wavelength.

[0018] The bonding apparatus of the present invention includes a chamber whose air pressure can be freely controlled, an inert gas supply pipe that supplies an inert gas to the chamber, and an ultraviolet irradiation mechanism, a cross-linking material spray mechanism, and a bonding mechanism, which are arranged in the chamber. According to this invention, it is possible to provide a bonding apparatus that can firmly bond substrates containing polymers on their surfaces at low temperatures.

[0019] A laminate in which a first substrate containing a polymer on its surface, a crosslinked layer, and a second substrate containing a polymer on its surface are laminated in this order. According to this invention, it is possible to provide a laminate that can be used in high-frequency circuits by bonding substrates containing polymers on their surfaces.

[0020] According to the present invention, it is possible to provide a method for joining substrates containing a polymer on their surfaces, a joining device, and a laminate that can be used in high-frequency circuits for firmly joining substrates containing a polymer on their surfaces at low temperatures.

[0021] FIG. 1 is a schematic diagram illustrating a step of joining a first substrate and a second substrate according to an embodiment of the present invention. FIG. 2 is a schematic diagram illustrating a step of joining a first substrate and a second substrate according to an embodiment of the present invention. FIG. 3 is a schematic diagram illustrating a step of joining a first substrate and a second substrate according to an embodiment of the present invention. FIG. 4 is a schematic diagram illustrating a step of joining a first substrate and a second substrate according to an embodiment of the present invention. FIG. 5 is a schematic diagram illustrating a step of joining a first substrate and a second substrate according to an embodiment of the present invention. FIG. 6 is a schematic diagram illustrating a step of joining a first substrate and a second substrate according to an embodiment of the present invention. FIG. 7 is a schematic diagram illustrating a step of joining a first substrate and a second substrate according to an embodiment of the present invention. FIG. 8 is a schematic diagram illustrating a step of joining a first substrate and a second substrate according to an embodiment of the present invention. FIG. 9 is a schematic diagram illustrating a step of joining a first substrate and a second substrate according to an embodiment of the present invention. FIG. 1 is a perspective view of a substrate supported by a substrate support according to an embodiment of the present invention. FIG. 2 is an enlarged perspective view of a main part of a bonding apparatus according to an embodiment of the present invention. FIG. 3 is an enlarged perspective view of a main part of a bonding apparatus according to an embodiment of the present invention. FIG. 4 is an enlarged perspective view of a main part of a bonding apparatus according to an embodiment of the present invention. FIG. 5 is an enlarged perspective view of a main part of a bonding apparatus according to an embodiment of the present invention. FIG. 6 is an enlarged perspective view of a main part of a bonding apparatus according to an embodiment of the present invention. FIG. 7 is a cross-sectional view of a laminate according to an embodiment of the present invention.

[0022] 1 to 5 are schematic diagrams illustrating a step of joining a first substrate and a second substrate according to a first embodiment of the present invention. The step of joining a first substrate and a second substrate according to this embodiment will be described with reference to these figures. (Joining Step 1-1. Preparation of First Substrate and Second Substrate) As shown in FIG. 1, a first substrate 61 and a second substrate 62 containing a polymer on their surfaces are prepared.

[0023] (Bonding step 1-2. Formation of precursor layer by ultraviolet light) Next, as shown in Fig. 2, first ultraviolet light 5 is irradiated to one or both of the bonding surface 61a of the first substrate 61 and the bonding surface 62a of the second substrate 62 in a state where a certain concentration of cross-linking substance 4 is present. In this embodiment, the first ultraviolet light 5 is irradiated to both the bonding surface 61a of the first substrate 61 and the bonding surface 62a of the second substrate 62 in a state where a certain concentration of cross-linking substance 4 is present. As shown in Fig. 3, precursor layers 61a, 61a are formed on the surfaces of both substrates 61, 62 by this irradiation with first ultraviolet light 5.

[0024] (Bonding Step 1-3: Bonding of First Substrate and Second Substrate) The first substrate 61, on which the precursor layers 61b, 61b have been formed, and the second substrate 62 are brought into contact with each other so that the precursor layers 61b, 61b face each other, as shown in FIG. 4. As shown in FIG. 5, the precursor layers 61b, 61b come into contact with each other, forming a crosslinked layer 41, and the first substrate 61 and the second substrate 62 are bonded by the crosslinked layer 41. In this way, a laminate 1 can be obtained in which the first substrate 61, the crosslinked layer 41, and the second substrate 62 are laminated in this order. During the bonding in this step, the laminate 1 may be heated, which can further improve the bonding strength.

[0025] (Process Environment) Forming the precursor layer 61b and bonding the first substrate 61 and the second substrate 62 are performed in an environment in which the oxygen concentration and the moisture concentration are controlled. This control of the oxygen concentration and the moisture concentration may be performed in a vacuum or a nitrogen atmosphere. Alternatively, other inert gases may be selected instead of nitrogen. Examples of inert gases that may be selected include nitrogen, helium, neon, argon, and mixtures of any combinations thereof.

[0026] (First Substrate, Second Substrate) In this embodiment, the first substrate 61 and the second substrate 62 may be any of polymer films such as LCP (liquid crystal polymer), PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer), PTFE (polytetrafluoroethylene), COP (cycloolefin polymer), PPS (polyphenylene sulfide), PEEK (polyether ether ketone), PI-based (including PI (polyimide) and MPI (modified polyimide)), and PPE-based (including PPE (polyphenylene ether) and mPPE (modified polyphenylene ether)), graphite sheets, or laminates of combinations thereof. These materials may be selected based on desired high-frequency circuit characteristics, gas permeability characteristics, moisture-proof characteristics, etc. The polymer of the present invention includes not only polymer films but also graphite sheets obtained by sintering such films at high temperatures.

[0027] (Crosslinking Substance) The crosslinking substance present during UV irradiation may be any one or any combination selected from the group consisting of ammonia, primary alcohols, and secondary alcohols. These crosslinking substances during UV irradiation may be in gaseous form, mist (droplets), or a mixture thereof. The alcohol compound is preferably one that is likely to generate hydroxyl radicals and CH radicals upon UV irradiation, resulting in the generation of carboxyl groups, due to the bonding action described below. It is particularly preferable for the alcohol compound to have 1 to 5 carbon atoms. Examples of such alcohol compounds include methanol, ethanol, 1-propanol, 1-butanol, 1-pentanol, 2-propanol, 2-butanol, 2-pentanol, isobutyl alcohol, isoamyl alcohol, tert-butyl alcohol, and tert-amyl alcohol. Of these, primary alcohols having 1 to 5 carbon atoms are preferred, and primary alcohols having 2 to 5 carbon atoms are more preferred because they are less harmful (they are less likely to produce harmful formaldehyde, formic acid, etc. in the human body), with ethanol, 1-propanol, 1-butanol, or 1-pentanol being even more preferred, ethanol and 1-propanol being particularly preferred, and ethanol being most preferred.

[0028] (Ultraviolet Light) The ultraviolet light irradiated in the presence of a certain concentration of a crosslinking substance may have a dominant wavelength of 156 nm, 172 nm, 185 nm, 206 nm, 222 nm, 254 nm, 283 nm, or 308 nm. As a source of ultraviolet light having these wavelengths, a source having the desired wavelength can be appropriately selected, such as a low-pressure mercury lamp, a high-pressure mercury lamp, an excimer lamp, or a deep ultraviolet LED.

[0029] (Precursor Layer and Crosslinked Layer) When the substrates 61 and 62 are made of polyimide, the precursor layer 61b of the first substrate 61 and the second substrate 62 has a structure containing a crosslinkable polymer as shown in Chemical Formula 1 below. In the figure, the dashed line R-R indicates the vicinity of the surface of the substrates 61 and 62. The end of A in the figure is -C(=O)-O-H or -CH ３ Represents.

[0030]

[0031] As shown in Chemical Formula 1, most of the ends of the alkyl chain bridges are -C(=O)-O-H or -CH ３ As shown in the following [Chemical Formula 2] (A-1), when one end D and the other end E come close to each other, H ２ O is removed and both ends are bonded via the O atom (B-1). Also, as shown in (A-2), CH ３ In the case of the OH group, it also bonds with the OH group coming from the other side, and similarly H ２ O is removed, and both ends are bonded via the O atom (B-1). The dashed lines in the formula represent hydrogen bonds. The bonds by oxygen O in formula (B-1) can be hydrolyzed, but they can be converted to -C(=O)-O-H or -CH ３ Therefore, even if decomposition occurs, recombination occurs at the same time, and the mutual bond is maintained.

[0032]

[0033] As described above, in the method of this embodiment for bonding a first substrate and a second substrate, each of which contains a polymer on its surface, ultraviolet light is irradiated in a state in which a crosslinking substance, which is one or a combination of ammonia, primary alcohol, and secondary alcohol, is present at a certain concentration, to form a precursor layer. By bringing these precursor layers into contact with each other, a crosslinked layer is formed, and the first substrate and the second substrate are bonded via this crosslinked layer, thereby providing a bonding method for firmly bonding the first substrate and the second substrate at low temperature. The first substrate and the second substrate can be selected from LCP (liquid crystal polymer), PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer), PTFE (polytetrafluoroethylene), COP (cycloolefin polymer), PPS (polyphenylene sulfide), PEEK (polyether ether ketone), PI-based (including PI (polyimide) and MPI (modified polyimide)), PPE-based (including PPE (polyphenylene ether) and mPPE (modified polyphenylene ether)) polymer films, graphite sheets, or laminates of combinations thereof, so that materials suitable for use in high-frequency circuits can be appropriately selected. Therefore, a method for joining substrates containing polymers on their surfaces suitable for use in high-frequency circuits can be provided, which firmly bonds the first substrate and the second substrate at low temperatures.

[0034] Second Embodiment Next, a second embodiment of the present invention will be described. The second embodiment differs from the first embodiment in that, before forming the precursor layers 61b, 61b of the first substrate 61 and the second substrate 62 shown in FIGS. 2 and 3, second ultraviolet light 8 is irradiated onto one or both of the bonding surface 61a of the first substrate 61 and the bonding surface 62a of the second substrate 62, as shown in FIG. 6. In this embodiment, the second ultraviolet light 8 is irradiated onto both the bonding surface 61a of the first substrate 61 and the bonding surface 62a of the second substrate 62. The remaining steps are the same as those in the first embodiment. By adding this step to the first embodiment, in addition to the effects of the first embodiment, the surface conditions of the bonding surface 61 a of the first substrate 61 and the bonding surface 62 a of the second substrate 62 before the formation of the precursor layers 61 b, 61 b ​​are improved by removing moisture and impurities from the surfaces thereof, thereby improving the bonding between the first substrate 61 and the precursor layer 61 b ​​and between the second substrate 62 and the precursor layer 61 b ​​and the film quality of the precursor layers 61 b, 61 b, and as a result, improving the bonding strength between the first substrate 61 and the second substrate 62. Note that the second ultraviolet light 8 may have a dominant wavelength of 156 nm, 172 nm, 185 nm, 206 nm, 222 nm, 254 nm, 283 nm, or 308 nm.

[0035] Third Embodiment FIG. 1 and FIGS. 7 to 11 are schematic diagrams illustrating a bonding process between a first substrate and a second substrate according to a third embodiment of the present invention. The bonding process between a first substrate and a second substrate according to this embodiment will be described with reference to these figures. (Bonding Process 3-1. Preparation of First and Second Substrates) As shown in FIG. 1, a first substrate 61 and a second substrate 62 are prepared. (Bonding Process 3-2. Formation of Insulating Film) As shown in FIG. 7, an insulating film 61c is formed on either or both of the bonding surface 61a of the first substrate 61 and the bonding surface 62a of the second substrate 62. In this embodiment, the insulating film 61c is formed on both bonding surfaces 61a, 62a. The method for forming the insulating film 61c may be selected from ion beam sputtering, ALD, magnetron sputtering, CVD, or the like, depending on the desired properties of the insulating film 61c.

[0036] (Bonding step 3-3. Irradiation of ultraviolet light) Next, as shown in Fig. 8, first ultraviolet light 5 is irradiated in a state in which a certain concentration of cross-linking substance 4 is present on one or both of the bonding surfaces of the first substrate 61 and the second substrate 62. In this embodiment, first ultraviolet light 5 is irradiated in a state in which a certain concentration of cross-linking substance 4 is present on the insulating films 61c on both the bonding surfaces of the first substrate 61 and the second substrate 62. As shown in Fig. 9, a precursor layer 61b is formed by this irradiation of first ultraviolet light 5.

[0037] (Bonding Step 3-4. Bonding of First Substrate and Second Substrate) The first substrate 61 and the second substrate 62, each having the precursor layers 61b, 61b formed thereon, are brought into contact with each other so that the precursor layers 61b face each other, as shown in FIG. 10. As shown in FIG. 11, the precursor layers 61b come into contact with each other, forming a crosslinked layer 41, and the first substrate 61 and the second substrate 62 are bonded by the crosslinked layer 41. In this way, a laminate 10 can be obtained in which the first substrate 61, the insulating film 61c, the crosslinked layer 41, the insulating film 61c, and the second substrate 62 are laminated in this order. During the bonding in this step, the laminate 10 may be heated, which can further improve the bonding strength.

[0038] This embodiment differs from the first embodiment in that an insulating film 61c is formed between the first substrate 61 and the crosslinked layer 41, and between the second substrate 62 and the crosslinked layer 41. Other steps are the same as those in the first embodiment. For example, the first ultraviolet light 5 used in this embodiment may have a dominant wavelength of 156 nm, 172 nm, 185 nm, 206 nm, 222 nm, 254 nm, 283 nm, or 308 nm, as in the first embodiment. The materials, configurations, and types of crosslinking substances of the first substrate 61 and the second substrate 62 are the same as those in the first embodiment. Furthermore, the structure of the precursor layer 61b formed on the insulating film 61c is the same as that of [Chemical Formula 1] in the first embodiment, and the crosslinked layer 41 is formed (bonded) using —C(═O)—O—H or —CH, which are the terminals of the alkyl chain crosslinks in the first embodiment. ３ H from contact with peers ２ This is due to the same effect as [Chemical Formula 2], which explains the bonding due to the removal of 0.

[0039] As described above, in this embodiment, when bonding the first substrate 61 and the second substrate 62, the insulating films 61c are formed on the bonding surfaces 61a and 62a, and the precursor layers 61b are formed on the insulating films 61c and 61c. The bonding of the first substrate 61 and the second substrate 62 is performed by bonding the precursor layers 61b and 61b on the insulating films 61c and 61c. Therefore, the cross-linked layer 41 made of the precursor layers 61b and 61b made of the same material can be bonded relatively easily, and therefore the bonding strength between the first substrate 61 and the second substrate 62 can be improved.

[0040] Fourth Embodiment Next, a fourth embodiment of the present invention will be described. The fourth embodiment differs from the third embodiment in that, before forming the precursor layer 61b of the insulating film 61c shown in FIGS. 8 and 9, as shown in FIG. 12, second ultraviolet light 8 is irradiated onto one or both of the insulating film 61c on the bonding surface 61a of the first substrate 61 and the insulating film 61c on the bonding surface 62a of the second substrate 62. In this embodiment, the second ultraviolet light 8 is irradiated onto both of the insulating films 61c. The remaining steps are the same as those of the third embodiment. By adding this step to the third embodiment, in addition to the effects of the third embodiment, the surface condition of the insulating film 61c before the formation of the precursor layer 61b is improved by removing moisture and impurities from the surface of the insulating film 61c. This improves the bond between the insulating film 61c and the precursor layer 61b and the film quality of the precursor layer 61b. As a result, the bonding strength between the first substrate 61 and the second substrate 62 can be improved. The second ultraviolet light 8 may have a dominant wavelength of any of 156 nm, 172 nm, 185 nm, 206 nm, 222 nm, 254 nm, 283 nm, and 308 nm.

[0041] Fifth Embodiment Next, a fifth embodiment of the present invention will be described. The fifth embodiment differs from the third embodiment in that, before forming the insulating film 61c shown in FIG. 7, third ultraviolet light 9 is irradiated onto one or both of the bonding surface 61a of the first substrate 61 and the bonding surface 62a of the second substrate 62, as shown in FIG. 13 . In this embodiment, the third ultraviolet light 9 is irradiated onto both the bonding surface 61a of the first substrate 61 and the bonding surface 62a of the second substrate 62. Other steps are the same as those in the third embodiment. By adding this step to the third embodiment, in addition to the effects of the third embodiment, the surface condition of the bonding surface 61a of the first substrate 61 and the bonding surface 62a of the second substrate 62 before forming the insulating film 61c is improved by removing moisture and impurities from the surfaces. This improves the bond between the first substrate 61 and the insulating film 61c, the bond between the second substrate 62 and the insulating film 61c, and the film quality of the insulating films 61c and 61c. As a result, the bond strength between the first substrate 61 and the second substrate 62 can be improved. The third ultraviolet light 9 may have a dominant wavelength of any one of 156 nm, 172 nm, 185 nm, 206 nm, 222 nm, 254 nm, 283 nm, and 308 nm.

[0042] <Sixth embodiment> Fig. 14 is a perspective view of a bonding apparatus 200 according to a sixth embodiment of the present invention. Figs. 17 to 22 are enlarged perspective views of the main parts of the bonding apparatus 200. The bonding apparatus 200 includes chambers 201a to 201f whose air pressures can be freely controlled, an inert gas supply source 202 that supplies an inert gas to the chambers 201a to 201f, ultraviolet irradiation mechanisms 203 that are disposed in the chambers 201a, 201c, and 201d, a cross-linking material spray mechanism 204 that is disposed in the chamber 201d, and a bonding mechanism 209 that is disposed in the chamber 201e.

[0043] Fig. 15 shows a perspective view of a first substrate 61 supported by a substrate support 63. Fig. 16 shows a perspective view of a second substrate 62 supported by a substrate support 65. As shown in Fig. 14, the chambers 201a-201f are connected to each other by gate valves 205. By opening and closing the gates of the gate valves 205, the first substrate 61 and the second substrate 62 can be transferred between the chambers 201a-201f while maintaining the airtightness of the chambers 201a-201f.

[0044] Each of the chambers 201a-201f is connected to an air pressure control source 215 via an air pressure control pipe 215a and to an inert gas supply source 202 via an inert gas supply pipe 202a. The air pressure control source 215 is configured, for example, with a vacuum pump, an exhaust valve, etc., and freely controls the air pressure within each of the chambers 201a-201f. Examples of the inert gas supplied from the inert gas supply source 202 include nitrogen, helium, neon, argon, and mixtures of any combination thereof that can be supplied to each chamber. For the sake of conceptual explanation, FIG. 14 illustrates the air pressure control source 215 as being connected to each of the chambers 201a-201f via an air pressure control pipe 215a. However, the air pressure of each of the chambers 201a-201f can be freely controlled independently. More specifically, a separate air pressure control source 215 is provided for each of the chambers 201a-201f. Similarly, the inert gas is supplied to each of the chambers 201a to 201f independently.

[0045] As shown in Fig. 17, chamber 201a includes a gate valve 205 and an ultraviolet irradiation mechanism 203. Chamber 201a functions as a substrate introduction and UV irradiation unit that introduces substrates into bonding apparatus 200 and irradiates the bonding surfaces of substrates 61 and 62 with ultraviolet light. As shown in Fig. 18, chamber 201b includes a gate valve 205 and an ion beam sputtering mechanism 207. Chamber 201b functions as an ion beam sputtering unit that forms a thin film by ion beam sputtering on the bonding surfaces of substrates 61 and 62.

[0046] As shown in Fig. 19, chamber 201c includes a gate valve 205 and an ultraviolet irradiation mechanism 203. Chamber 201c functions as a UV irradiation unit that irradiates ultraviolet rays onto the bonding surfaces of substrates 61 and 62. As shown in Fig. 20, chamber 201d includes a gate valve 205, an ultraviolet irradiation unit 203, and a cross-linking material spraying mechanism 204. Chamber 201d functions as a cross-linking material spraying unit that sprays a cross-linking material onto the bonding surfaces of substrates 61 and 62 while irradiating them with ultraviolet rays.

[0047] As shown in FIG. 21 , chamber 201e includes a substrate reversing mechanism 208 and a bonding mechanism 209. The substrate reversing mechanism 208 includes a substrate holding unit 208a and a substrate reversing unit 208b. The bonding mechanism 209 includes an upper pressure mechanism 209a, a lower pressure mechanism 209b, and a substrate holding mechanism 209c. In the substrate chamber 201e, the substrate reversing mechanism 208 holds one substrate, inverts the other substrate to bring them into contact, and the bonding mechanism 209 functions as a substrate bonding unit that bonds the substrates 61 and 62. As shown in FIG. 22 , chamber 201f includes a gate valve 205. Chamber 201f functions as a substrate unloading unit that unloads the bonded substrates 61 and 62 to the outside of the bonding apparatus 200.

[0048] Next, the operation of the bonding apparatus 200 configured as described above will be described. First, the first substrate 61 is placed in chamber 201a (substrate introduction and UV irradiation section) with its bonding surface facing downward. The gate valve 205 is closed, and after the desired atmosphere is set in chamber 201a, ultraviolet light is irradiated onto the bonding surface of the first substrate 61 by the ultraviolet light irradiation mechanism 203. After the ultraviolet light irradiation is completed, the gate valve 205 is opened, and the first substrate 61 is transported to chamber 201b, where the gate valve 205 is closed. Furthermore, the second substrate 62 is placed in the same manner as the first substrate 61, and is subjected to the same processing as the first substrate. Here, each of chambers 201b-201f is set to a predetermined atmosphere.

[0049] The first substrate 61 transported to chamber 201b (ion beam sputtering unit) has an insulating film formed on its bonding surface while passing above it by an ion beam sputtering mechanism 207, with the chamber 201b being kept at a desired atmosphere. After the insulating film formation is completed, the first substrate 61 is transported to chamber 201c by opening gate valve 205. Subsequently, a second substrate 62 is transported to chamber 201b and subjected to the same treatment as the first substrate 61.

[0050] The first substrate 61 transported to chamber 201c (UV irradiation section) has its bonding surface irradiated with ultraviolet light by ultraviolet irradiation mechanism 203 while the interior of chamber 201c is kept at a desired atmosphere. After ultraviolet irradiation is completed, gate valve 205 is opened and the first substrate 61 is transported to chamber 201d. Subsequently, second substrate 62 is transported to chamber 201c and subjected to the same treatment as that for first substrate 61.

[0051] The first substrate 61 is transported to chamber 201d (cross-linking material spraying section), and a cross-linking material is sprayed into chamber 201d by cross-linking material spraying mechanism 204 while the chamber 201d is maintained at a desired atmosphere. The bonding surface of the first substrate 61 is irradiated with ultraviolet light by ultraviolet irradiation mechanism 203, with a certain concentration of cross-linking material present on the bonding surface. After ultraviolet irradiation is complete, gate valve 205 is opened and the first substrate 61 is transported to chamber 201e. Subsequently, a second substrate 62 is transported to chamber 201e and subjected to the same treatment as the first substrate 61.

[0052] The first substrate 61 transported to chamber 201e (substrate bonding section) is moved to and held by substrate holder 208a, which is arranged at the top of substrate inverting mechanism 208, with the chamber 201d being adjusted to a desired atmosphere. Next, a second substrate 62, which has been processed in the same manner as the first substrate 61, is transported to chamber 201e. The second substrate 62 is held by substrate inverting section 208b of substrate inverting mechanism 208 and inverted 180 degrees so that the bonding surface of the second substrate 62 faces upward. The first substrate 61 held above it is lowered to the position of the second substrate 62, and the bonding surfaces of the two substrates are brought into contact with each other, forming a single unit, and then transported to bonding mechanism 209.

[0053] In the bonding mechanism 209, the integrated first substrate 61 and second substrate 62 are held by a substrate holding mechanism 209c, and pressure is applied from both above and below by an upper pressure mechanism 209a located above and a lower pressure mechanism 209b located below the substrate holding mechanism 209c. The upper pressure mechanism 209a and the lower pressure mechanism 209b are equipped with heaters (not shown) and are heated to a desired temperature depending on the type of the first substrate 61 and the second substrate 62 to achieve a desired bonding state. The pressure applied by the upper pressure mechanism 209a and the lower pressure mechanism 209b brings the first substrate 61 and the second substrate 62 into contact and pressurize via precursors formed on their respective bonding surfaces, ultimately forming a crosslinked layer that firmly bonds the first substrate 61 and the second substrate 62. The bonded, integrated first substrate 61 and second substrate 62 are transported to chamber 201f.

[0054] The bonded first substrate 61 and second substrate 62 transported to chamber 201f (substrate unloading section) are unloaded outside the bonding apparatus 200 after the gate valve 205 is closed and the pressure inside chamber 201d is returned to atmospheric pressure.

[0055] As described above, in the bonding apparatus 200 of this embodiment, the bonding process of the first substrate 61 and the second substrate 62 is performed sequentially in the chambers 201a-201f where the air pressure, moisture concentration, etc. are adjusted. The bonding process is composed of the following steps a) to f): a) UV irradiation of the bonding surfaces as a pretreatment (chamber 201a), b) formation of an insulating film (chamber 201b), c) UV irradiation of the insulating film (chamber 201c), d) formation of a precursor layer by UV irradiation in the presence of a certain concentration of cross-linking substance (chamber 201d), e) bonding of the substrates (chamber 201e), and f) removal of the bonded substrates (chamber 201f). Therefore, by performing the necessary steps sequentially and continuously, a laminate can be produced efficiently.

[0056] The bonding device 200 is equipped with a chamber 201d that irradiates the bonding surfaces with ultraviolet light while spraying a cross-linking material using a cross-linking material spraying mechanism 204. This allows a precursor layer to be formed on the bonding surfaces of the substrates 61 and 62, and the substrates 61 and 62 to be firmly bonded to each other at low temperatures by the cross-linking layer formed by contacting the precursor layer.

[0057] If an insulating film is not required depending on the type of substrate and the bonding state, step b) (chamber 201b) can be omitted. Similarly, the ultraviolet irradiation in steps a) and c) may also be omitted depending on the type of substrate and the bonding state. Since the bonding device 200 is configured by connecting multiple chambers 201a-201f, unnecessary chambers may be removed depending on the combination of bonding steps.

[0058] Seventh Embodiment FIG. 23 is a cross-sectional view of a laminate 300 according to a seventh embodiment of the present invention. The method for forming the laminate 300 in this embodiment is the same as that in the first embodiment. The difference is that substrates 67, 67 each having a circuit coated with an organic substance are used as the first and second substrates. As shown in FIG. 23, the substrate 67 having a circuit coated with an organic substance has a circuit layer 67b formed on a substrate 67a, and an organic substance 67c coated on the circuit of the circuit layer 67b. Other structural functions are the same as those of the first embodiment, and the same effects as those of the first embodiment are achieved. According to this embodiment, even substrates including a circuit layer can be firmly bonded together at low temperatures by the cross-linked layer 41 adjacent to the organic substance 67a. Because bonding can be performed at low temperatures, a laminate can be formed without damaging the circuit.

[0059] Eighth Embodiment FIG. 24 is a cross-sectional view of a laminate 400 according to an eighth embodiment of the present invention. The method for forming the laminate 400 in this embodiment is the same as that in the first embodiment. The difference is that substrates 69, 69, each including a conductive region, are used as the first and second substrates. As shown in FIG. 24, the substrate 69 including a conductive region has a conductive region 69b formed therein that penetrates the circuit layers 69a and electrically connects the circuit layers 69a to each other. Other structural features are similar to those of the first embodiment, and the same effects and advantages are achieved. According to this embodiment, even substrates including circuit layers 69a can be firmly bonded to each other at low temperatures by the bridging layer 41. Bonding at low temperatures allows a laminate to be formed without damaging the circuitry. Furthermore, the bridging layer 41 does not have a high enough resistance to impair electrical connection between the conductive regions 69b, thereby electrically connecting the circuit layers 69a of the substrates 69 to each other.

[0060] Examples will be described below. Table 1 shows data obtained by irradiating the bonding surface with VUV (172 nm / 185 nm) in the atmosphere and measuring the contact angle and bonding strength as the irradiation time changes. The contact angle was measured as a parameter to confirm the formation of OH, CHO, COOH, etc. In Table 1 below, sample A is untreated, followed by samples B, C, D, and E, where data was obtained by varying the irradiation time from 60 seconds, 120 seconds, 180 seconds, and 300 seconds. A single 110 W low-pressure mercury lamp was used for VUV irradiation, with an irradiation distance of 20 mm and a wavelength of 254 nm, resulting in a 30 mW / cm ２ At a wavelength of 185 nm, 5 mW / cm ２ As can be seen from Table 1, VUV irradiation reduces the contact angle and increases the bond strength. When the irradiation time is 120 seconds or longer, both the contact angle and bond strength reach a constant value, indicating that sufficient bond strength is obtained.

[0061]

[0062] With regard to the above description of the specification, the claims encompass many modifications to the embodiments within the scope that does not depart from the technical idea of ​​the present invention. Therefore, the embodiments disclosed in this specification are presented for illustrative purposes and should not be considered as limiting the scope of the present invention.

[0063] 1, 10, 300, 400 Laminate 4 Cross-linking material 41 Cross-linked layer 5 First ultraviolet light 8 Second ultraviolet light 9 Third ultraviolet light 61 First substrate 61a Bonding surface of first substrate 61b Precursor layer 61c Insulating film 62 Second substrate 62a Bonding surface of second substrate 67 Substrate with organic material coated on circuit 67b Circuit (layer) 67c Organic material 69 Substrate including a conductive region in part 69b Conductive region 200 Bonding device 201a-201f Chamber 202a Inert gas supply pipe 203 Ultraviolet light irradiation mechanism 204 Cross-linking material spray mechanism 209 Bonding mechanism

Claims

1. 1. A method for bonding a substrate containing a polymer to a surface thereof, comprising the steps of: forming a precursor layer by irradiating a first ultraviolet ray to one or both of a bonding surface of the first base material and a bonding surface of the second base material in a state in which a crosslinking substance is present at a certain concentration; bringing the first substrate and the second substrate into contact with each other to bond the first substrate and the second substrate to each other via the precursor layer; A method for bonding substrates containing a polymer on a surface thereof, comprising:

2. 1. A method for bonding a substrate containing a polymer to a surface thereof, comprising the steps of: forming an insulating film on either or both of the bonding surface of the first base material and the bonding surface of the second base material; forming a precursor layer by irradiating a first ultraviolet ray in a state in which a crosslinking substance is present at a certain concentration on either or both of the bonding surface of the first base material and the bonding surface of the second base material; bringing the first substrate and the second substrate into contact with each other to bond the first substrate and the second substrate to each other via the precursor layer; A method for bonding substrates containing a polymer on a surface thereof, comprising:

3. irradiating one or both of a bonding surface of the first base material and a bonding surface of the second base material with a second ultraviolet ray before forming the precursor layer; 3. A method for bonding substrates containing a polymer on the surface thereof according to claim 1 or 2, comprising:

4. irradiating one or both of a bonding surface of the first base material and a bonding surface of the second base material with a third ultraviolet ray before forming the insulating film; 3. A method for bonding substrates containing a polymer on a surface thereof according to claim 2, comprising:

5. 3. The method for bonding substrates containing a polymer on a surface thereof according to claim 1, wherein the forming of the precursor layer and the bonding are carried out in an environment in which oxygen concentration and moisture concentration are controlled.

6. 6. The method for bonding substrates containing a polymer on the surface thereof according to claim 5, wherein the oxygen concentration and the moisture concentration are controlled in a vacuum or an inert gas atmosphere.

7. 3. The method for bonding substrates containing a polymer on a surface thereof according to claim 1 or 2, wherein the first and second substrates are any one of polymer films selected from the group consisting of liquid crystal polymer, tetrafluoroethylene-perfluoroalkylvinylether copolymer, polytetrafluoroethylene, cycloolefin polymer, polyphenylene sulfide, polyetheretherketone, polyimide, polyimide-based films including modified polyimide, polyphenylene ether, and polyphenylene ether-based films including modified polyphenylene ether, graphite sheets, and laminates of combinations thereof.

8. 3. The method for bonding substrates containing a polymer on the surface according to claim 1, wherein the first and second substrates are substrates having a circuit board coated with an organic substance.

9. 3. The method for bonding substrates containing a polymer on a surface thereof according to claim 1 or 2, wherein the first and second substrates are substrates which include a conductive region on at least a part of the surface.

10. 3. The method for bonding substrates containing a polymer on the surface thereof according to claim 1 or 2, wherein the cross-linking substance is any one or any combination selected from the group consisting of ammonia, primary alcohols, and secondary alcohols.

11. 3. The method for bonding substrates containing a polymer on the surface thereof according to claim 1 or 2, wherein the first ultraviolet ray, the second ultraviolet ray, and the third ultraviolet ray have a dominant wavelength of any one of 156 nm, 172 nm, 185 nm, 206 nm, 222 nm, 254 nm, 283 nm, and 308 nm, or any combination thereof.

12. A chamber capable of freely controlling air pressure; an inert gas supply pipe for supplying an inert gas to the chamber; disposed within the chamber; An ultraviolet irradiation mechanism; A cross-linking material spraying mechanism; A joining device comprising:

13. A laminate in which a first substrate containing a polymer on its surface, a crosslinked layer, and a second substrate containing a polymer on its surface are laminated in this order.