CN112996658A

CN112996658A - Laminate, method for producing same, and method for producing printed wiring board

Info

Publication number: CN112996658A
Application number: CN201980072440.9A
Authority: CN
Inventors: 伊藤卓; 福岛直树
Original assignee: Kaneka Corp
Current assignee: Kaneka Corp
Priority date: 2018-11-01
Filing date: 2019-10-24
Publication date: 2021-06-18
Also published as: JP7265560B2; JPWO2020090631A1; WO2020090631A1; TW202029854A

Abstract

A laminate (100) is provided with a release sheet (21) and a flexible film-like substrate (11) which are laminated in this order on a first main surface of a rigid support (30). The film-like substrate may include a flexible insulating resin film and a metal conductor layer provided on a principal surface of the insulating resin film. The outer periphery of the support projects outward from the outer periphery of the release sheet, and the outer periphery of the film-like base projects outward from the outer periphery of the release sheet. In a region (8) outside the outer periphery of the release sheet, the support body is bonded to the film-like base material.

Description

Laminate, method for producing same, and method for producing printed wiring board

Technical Field

The present invention relates to a laminate, a method for producing the same, and a method for producing a printed wiring board using the laminate.

Background

Printed circuit boards having a circuit formed of a metal conductor on an insulating substrate are roughly classified into rigid printed circuit boards and flexible printed circuit boards. Flexible printed circuit boards, which utilize their flexibility, are mainly used for applications in which a substrate is compactly folded and housed inside an electronic device.

In the manufacturing process of printed wiring boards, various chemical solutions are used for forming a metal conductor layer by wet plating, patterning the metal conductor layer by wet etching, developing an etching resist layer, desmear treatment, and the like. In the manufacturing process of a rigid printed wiring board, a rigid substrate in a sheet form is used and processed in a batch manner. Since a flexible substrate is used for the flexible printed wiring board, the manufacturing process thereof is often performed by a so-called roll-to-roll process, and the processing accuracy is low as compared with a manufacturing process of a rigid printed wiring board in which a rigid substrate is used and processing is performed intermittently. For example, in a semiconductor package substrate classified as a rigid printed wiring board, a narrow pitch of circuit wiring is advanced, and a printed wiring board having a circuit width (line width/line pitch) of 10 μm or less has been mass-produced, whereas a circuit width of a flexible printed wiring board is about 20 μm even if it is small.

With the development of higher functions and smaller sizes of electronic devices, printed circuit boards are required to have a further narrow pitch and to have rigidity and flexibility for compact storage in electronic devices. In order to manufacture a rigid flexible substrate with a narrow pitch, it is necessary to form a narrow-pitch circuit on a flexible film substrate to the same extent as a rigid printed circuit board.

As a method for performing high-precision processing on a flexible film substrate, the following processes are proposed: a rigid laminate is formed by attaching a flexible film substrate to a rigid support such as a glass plate, and the flexible film substrate of the laminate is peeled from the support after processing such as printing and element formation (for example, patent document 1).

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2015-193101

Disclosure of Invention

Problems to be solved by the invention

As proposed in patent document 1, a laminate in which a flexible film base material is bonded to a rigid support is applicable to a batch process using a rigid substrate, and therefore, it is considered that a printed circuit board having a narrow pitch circuit on the flexible film base material in the same degree as that of a rigid printed circuit board can be formed. However, since various chemical solutions are used in the process of manufacturing a printed wiring board, the chemical solutions may penetrate into the lamination interface between the support and the flexible film substrate and cause undesirable peeling. Further, if the adhesive or the bonding agent provided at the lamination interface is dissolved in a chemical solution, it may cause contamination.

In order to prevent contamination due to poor adhesion or dissolution in a chemical solution, it is conceivable to use a photocurable or thermosetting adhesive to bond the support and the flexible film base more firmly, thereby preventing the chemical solution from entering the lamination interface and preventing the adhesive from dissolving in the chemical solution. However, when a curable adhesive material is used, it may be difficult to peel the processed flexible film substrate from the support, or the adhesive material may remain on the surface of the flexible film, which may cause contamination.

In view of the above circumstances, an object of the present invention is to provide a laminate applicable to a manufacturing facility of a rigid printed wiring board and a manufacturing method of a printed wiring board using the laminate.

Means for solving the problems

The laminate of the present invention includes a release sheet and a flexible film-like substrate, which are sequentially laminated on a first main surface of a rigid support. The film-like substrate includes a flexible insulating resin film such as a polyimide film. The film-like substrate may be formed of an insulating resin film, or may be provided with a metal conductor layer on at least one main surface of the insulating resin film.

In the laminate of the present invention, the outer periphery of the support and the outer periphery of the film-shaped base protrude outward from the outer periphery of the release sheet, and the support protruding outward from the outer periphery of the release sheet is bonded to the film-shaped base.

The outer periphery of the film-like base material may protrude outward from the outer periphery of the support. The release sheet may be provided with an opening, and the first main surface of the support body and the second main surface of the film-like substrate may be bonded at a portion of the release sheet where the opening is provided.

The laminate is obtained by, for example, hot-pressing a laminate in which a release sheet and a film-like substrate are arranged in this order on the first main surface of the support. The support protruding outward from the outer periphery of the release sheet is bonded to the film-like base material by hot pressing. For example, when the support is a prepreg, the resin impregnated in the prepreg is cured by heating, and thus exhibits adhesiveness.

The laminated body can be applied to the manufacture of printed circuit boards. In the production of a printed wiring board, a first circuit is formed on a first main surface of an insulating resin film of a laminate. For example, the first circuit is formed by etching a metal conductor layer provided on the first main surface of the insulating resin film. The first circuit may also be formed by pattern plating. Before the first circuit is formed, a metal conductor layer may be formed on the first main surface of the insulating resin film by wet or dry electroless plating or the like.

After forming the first circuit on the first main surface of the insulating resin film, the insulating resin film is separated from the support and the release sheet. For example, the outer peripheral edge portion of the support body to which the film-shaped substrate is bonded is cut out from the laminate, thereby separating the insulating resin film.

The insulating layer for covering the first main surface of the insulating resin film and the first circuit formed thereon may be provided, and the second circuit may be formed on the insulating layer to form a multilayer structure. The lamination may be performed before the insulating resin film is separated from the laminate, or the lamination may be performed after the insulating resin film is separated from the laminate. After the insulating resin film is separated from the laminate, a third circuit may be formed on the second main surface of the insulating resin film.

ADVANTAGEOUS EFFECTS OF INVENTION

Since a laminate in which a film-like base material is laminated on a rigid support with a release sheet interposed therebetween has rigidity, it is applicable to an apparatus for handling a rigid base material, such as a manufacturing facility for a rigid printed wiring board. Therefore, a printed wiring board having a film-like base material as a base, such as a flexible rigid wiring board, can be manufactured.

Since the support and the film-like base material are bonded to each other at the outer peripheral edge of the laminate, the chemical solution can be prevented from entering the lamination interface of the release sheet in the process of manufacturing the printed wiring board. Therefore, peeling of the film-like base material and contamination of the manufacturing process can be prevented in the process of forming a circuit or the like. In any stage after the circuit formation, the film-like base material can be easily separated from the laminate by cutting off the outer peripheral edge of the laminate.

Drawings

Fig. 1 is a schematic cross-sectional view of a laminate according to an embodiment.

Fig. 2 is a schematic plan view of a laminate according to an embodiment.

Fig. 3 is a schematic cross-sectional view of a laminate according to an embodiment.

Fig. 4 is a schematic cross-sectional view of a laminate according to an embodiment.

Fig. 5 is a schematic cross-sectional view of a laminate according to an embodiment.

Detailed Description

[ constitution of laminate ]

Fig. 1 is a cross-sectional view of a laminate 100 according to an embodiment, and fig. 2 is a plan view thereof. In the laminate 100, the release sheet 21 and the film-like substrate 11 are laminated in this order on one principal surface of the support 30. The release sheet 21 is smaller in size than the support 30 and the film-like base 11, and the outer peripheral end 3 of the support 30 and the outer peripheral end 1 of the film-like base 11 protrude outward from the outer peripheral end 2 of the release sheet 21.

In a region 7 in the center of the laminated body in the plane, a film-like substrate 11 is laminated on a support 30 with a release sheet 21 interposed therebetween. In the region 8 outside the outer peripheral end 2 of the release sheet 21, the support 30 and the film-like substrate 11 are in contact with each other, and both are bonded.

< support >

The support 30 has rigidity enough to be handled by a rigid printed wiring board manufacturing apparatus. The support 30 is required to have heat resistance and chemical resistance for application in the process of manufacturing a printed wiring board. Specific examples of the support 30 include a glass plate, a resin sheet, and a prepreg. The prepreg is a material having rigidity by impregnating a fibrous reinforcing material such as a nonwoven fabric or cloth made of glass fibers, carbon fibers, synthetic fibers, or the like with a thermosetting resin, a thermoplastic resin, or the like. The thickness of the support 30 is not particularly limited as long as it has rigidity. When the support 30 is a prepreg, the thickness is preferably 30 μm or more, and more preferably 80 μm or more, in order to provide sufficient rigidity.

The support 30 needs to have a function of adhering to the film-like substrate 11 in the outer peripheral region 8. When a substrate material having no adhesive function such as a glass plate or a resin sheet is used, an appropriate adhesive layer can be formed on the entire surface or the outer peripheral region of the substrate to provide adhesiveness to the film-like base material 11.

In practice, a prepreg is generally used for manufacturing a printed wiring board, and is advantageous in terms of durability, availability, price, and the like in the process, and is preferably used as the support 30. As the prepreg, a prepreg in a semi-cured state may be used. Since the resin component is cured by heating, the semi-cured prepreg exhibits adhesiveness to the film-shaped substrate 11 by laminating under heating by hot pressing or the like.

< film-like base Material >

The film-like substrate 11 is flexible and includes a flexible insulating resin film serving as a substrate material of a printed circuit board. The film-like substrate 11 may be an insulating resin film alone, or may be provided with a metal conductor layer for forming a circuit on one or both surfaces of the insulating resin film. After an insulating resin film is laminated on the support 30 with the release sheet 21 interposed therebetween, a metal conductor layer may be formed on the insulating resin film by electroless plating or the like.

(insulating resin film)

The insulating resin film is preferably a film having high adhesion to a conductor layer for forming a circuit and excellent heat resistance and chemical resistance. Examples of the resin material of the insulating resin film include polyimide, liquid crystal polymer, polyamide, polyethylene terephthalate (PET), polyphenylene sulfide (PPS), and the like. A polyimide film is preferably used as the insulating resin film because of its excellent heat resistance and chemical resistance and its small coefficient of thermal linear expansion.

The insulating resin film may have an adhesion layer for improving adhesion to a conductive layer such as a metal foil or a plating layer. For example, a thermoplastic resin layer as an adhesion layer may be provided on one or both sides of a highly heat-resistant (non-thermoplastic) resin layer as a core.

The thickness of the insulating resin film is not particularly limited as long as it has flexibility. The thickness of the insulating resin film is, for example, about 3 to 150 μm, and may be 5 to 100 μm, or 75 μm or less, 50 μm or less, 30 μm or less, or 20 μm or less. The smaller the thickness of the flexible film, the more difficult it is to handle the film alone, but the laminate 100 is formed by laminating the film-shaped substrate 11 together with the rigid support 30 and the release sheet 21, and the laminate 100 has rigidity. Therefore, even when the insulating resin film of the film-like substrate 11 has a small thickness, handling is easy.

(conductor layer)

The conductor layer provided on the surface of the insulating resin film is used for forming a circuit by patterning. Examples of the material of the conductor layer include metals such as Ni, Cr, Ti, Al, Zn, Sn, Cu, Ag, and Cu, and alloys containing these metals. Among them, copper or a copper alloy is preferable. Examples of the film-like substrate having a copper layer (or a copper alloy layer) as a conductor layer on the surface of an insulating resin film include a three-layer flexible copper-clad laminate, a laminated two-layer flexible copper-clad laminate, a cast two-layer flexible copper-clad laminate, a PVD flexible copper-clad laminate, and the like.

The thickness of the conductor layer is not particularly limited, and may be appropriately selected according to the specification of the printed wiring board to be manufactured. In the case of forming a fine circuit, the thickness of the conductor layer is preferably small. When a circuit is formed by an additive method (including a semi-additive method), the conductor layer on the insulating resin film is only required to function as a power supply layer at the time of electrolytic plating, and the thickness of the conductor layer is preferably 5 μm or less. When a circuit is formed by a subtractive method, the thickness of the conductor layer is usually about 10 to 100 μm.

The conductor layer is formed by, for example, wet or dry electroless plating. In the present specification, unless otherwise specified, not only wet chemical plating (chemical reduction plating and displacement plating), but also dry plating such as Physical Vapor Deposition (PVD) and Chemical Vapor Deposition (CVD) are included in the "chemical plating". The type of electroless plating may be selected as appropriate depending on the compatibility (e.g., adhesion) with the insulating resin film, the specification of the printed wiring board, and the like. For example, in a PVD-type flexible copper clad laminate, a copper layer is formed on an insulating resin film by a PVD method. Examples of the PVD method include sputtering, vapor deposition, and ion plating. The conductor layer formed by electroless plating may be used as a power feeding layer, and further formed thereon by electrolytic plating. The conductor layer may be a metal foil such as a copper foil. When a copper foil is used as the conductor layer, either a rolled copper foil or an electrolytic copper foil may be used.

< Release sheet >

As the release sheet 21 disposed between the support 30 and the film-like substrate 11, one having heat resistance at the time of formation of a laminate and in the process of manufacturing a printed wiring board using the laminate, capable of being easily peeled from the film-like substrate 11, and not contaminating the contact surface with the film-like substrate 11 is used. The release sheet 21 may have adhesion to the support 30 and/or the film-like substrate 11 as long as the contact surface with the film-like substrate 11 is not contaminated.

The thickness of the release sheet 21 is not particularly limited. If the thickness is too large, the height difference at the outer peripheral end 1 of the release sheet 21 becomes large, and there is a possibility that the adhesiveness between the support 30 and the film-like substrate 11 in the outer peripheral region 8 is lowered and peeling is caused by air bubbles. Therefore, the thickness of the release sheet 21 is preferably 200 μm or less, more preferably 100 μm or less, and further preferably 50 μm or less. The thickness of the release sheet may be 5 μm or more or 10 μm or more.

Examples of the heat-resistant resin material constituting the release sheet 21 include heat-resistant polyolefins such as polyvinyl chloride (PVC), polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), Polycarbonate (PC), Polyamide (PA), and polymethylpentene; polyarylate, fluorine-based resin (polytetrafluoroethylene (PTFE), Polychlorotrifluoroethylene (PCTFE), polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), Perfluoroalkoxyfluororesin (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), ethylene-tetrafluoroethylene copolymer (ETFE), ethylene-chlorotrifluoroethylene copolymer (ECTFE), etc.), polyimide, and the like.

The release sheet 21 may have a heat-resistant adhesive layer on one surface or both surfaces of the heat-resistant film. Examples of the adhesive of the heat-resistant adhesive layer include silicone resin adhesives and acrylic resin adhesives.

As the release sheet 21, a commercially available release sheet for press working of a printed wiring board can be used. Commercially available products of a release sheet having no adhesive layer, which is formed of a heat-resistant film, include "TPX" (product name of release sheet "OPULENT") manufactured by mitsui chemical corporation and "AFREX" manufactured by asahi glass corporation. A release sheet having no adhesive layer on the surface thereof has an advantage that the contact surface with the film-like substrate 11 is less likely to be contaminated. In particular, a fluorine-based resin film is excellent in heat resistance and releasability, and exhibits adhesion (slight adhesiveness) to a resin film or a conductor layer, and therefore, can be suitably used as a material for a release sheet.

Commercially available release sheets having a heat-resistant adhesive layer include "liolm" series (LE951, LE957, etc.) manufactured by TOYO-CHEM corporation, "KT" series (KT508ZZ, etc., polyester substrate) and "KY" series (KY5010, etc., polyimide substrate), polyimide film pressure-sensitive adhesive tapes (1030, 1030S, etc.) and polyester film pressure-sensitive adhesive tapes (2034, 2230GX), manufactured by OKAMOTO corporation.

< formation of laminate >

The release sheet 21 and the film-like substrate 11 are arranged on one main surface of the support 30, and the laminate is integrated to form the laminate 100. When the film-like substrate 11 has a conductor layer on the surface of the insulating resin film, the conductor layer is disposed so as to be on the outer side (the surface opposite to the release sheet 21).

The outer peripheral end 3 of the support 30 and the outer peripheral end 1 of the film-like substrate 11 both protrude outward beyond the outer peripheral end 2 of the release sheet 21. In order to achieve this state, the release sheet 21 is cut to a size smaller than the support body 30 by one, the film-like base material 11 is cut to a size larger than the release sheet 21 by one, and the support body 30 and the film-like base material 11 are aligned so as to be bonded to each other in the frame-like outer peripheral region 8.

The shape of the support 30 is not limited to a rectangle, and may be a rhombus, a polygon, a circle, or the like, depending on the shape of the printed wiring board or the like. The area of the support 30 is, for example, 50 to 10000cm²The left and right sides are set according to the specification of the process, the size of the printed circuit board, and the like.

The size of the release sheet 21 may be smaller than that of the support 30. Since the outer peripheral region 8 does not ultimately become a product, it is preferable to reduce the width of the outer peripheral region 8 as small as possible from the viewpoint of area efficiency. The width of the outer peripheral region 8 is preferably 50mm or less, more preferably 30mm or less, and further preferably 20mm or less. On the other hand, from the viewpoint of ensuring the adhesiveness between the support 30 and the film-like substrate 11 by the outer peripheral section 8, the width of the outer peripheral section 8 is preferably 1mm or more, more preferably 3mm or more, and further preferably 5mm or more. The area of the release sheet 21 is preferably 0.6 times or more, more preferably 0.8 times or more, and still more preferably 0.9 times or more the area of the support 30.

The size of the film-like substrate 11 may be larger than the release sheet 21. From the viewpoint of increasing the area utilization efficiency of the film-like substrate 11 and suppressing the material loss, the area of the film-like substrate 11 is preferably 1.8 times or less, more preferably 1.4 times or less, and still more preferably 1.1 times or less the area of the release sheet 21. On the other hand, as described above, in the outer periphery of the release sheet 21, it is preferable to secure the width of the outer peripheral region 8 in which the support 30 and the film-like substrate 11 protrude outward of the outer peripheral end of the release sheet 21, from the viewpoint of improving the adhesion between the support 30 and the film-like substrate 11. The amount of projection of the film-like base material 11 from the outer peripheral edge of the release sheet 21 is preferably 1mm or more, more preferably 3mm or more, and still more preferably 5mm or more.

If both the support 30 and the film-like substrate 11 protrude outward beyond the outer peripheral end of the release sheet 21, either the support 30 or the film-like substrate 11 may be larger in size, or both may be the same in size. In the formation of the laminate (for example, hot pressing) or the production process of the printed wiring board, the adhesive layer of the support 30 and the resin material (for example, a melt or a softened material of the prepreg impregnated resin) may surround and enter the surface of the laminate 100 (the surface of the film-like substrate 11), which may cause contamination of the printed wiring board as a product or the process. From the viewpoint of preventing contamination due to the support 30, as shown in fig. 1, the outer peripheral end 1 of the film-like base 11 preferably protrudes outward from the outer peripheral end 3 of the support 30.

The width of the region 9 of the film-like base material 11 protruding outward of the outer peripheral end 3 of the support 30 is preferably 1mm or more, more preferably 3mm or more, and still more preferably 5mm or more. On the other hand, if the amount of protrusion of the film-like base material 11 from the outer periphery of the support 30 (the width of the section 9) is too large, the material loss of the film-like base material becomes large, which may cause an increase in cost. Further, when the amount of projection of the film-like base material is large, handling of the laminate may be hindered. Therefore, the amount of projection of the film-like base material 11 is preferably 50mm or less, more preferably 30mm or less, and still more preferably 15mm or less. The area of the film-like substrate 11 is preferably 1.3 times or less, more preferably 1.2 times or less, and still more preferably 1.1 times or less the area of the support 30.

As described above, the support 30 and the film-like base material, which are larger in size than the release sheet 21, are prepared, and the support 30 and the film-like base material 11 are arranged in the region 8 outside the outer peripheral end of the release sheet so as to be bonded, and laminated and integrated. Holes for alignment may be formed in advance in the support 30, the release sheet 21, and the film-like substrate 11, and the support, the release sheet, and the film-like substrate may be positioned by pins or the like.

The support 30, the release sheet 21, and the film-like substrate 11 may be subjected to surface treatment such as plasma treatment or corona treatment on one or both surfaces before lamination. By performing the surface treatment, the adhesion between the layers can be improved.

The support 30, the release sheet 21, and the film-like substrate 11 can be integrally laminated by a method such as hot pressing, vacuum pressing, roll lamination, or vacuum lamination. In the lamination, it is preferable to adopt a method capable of bonding the support 30 and the film-like substrate 11 to each other in the outer peripheral region 8, and the lamination method and conditions may be selected depending on the bonding material of the support 30. For example, when the support 30 is a prepreg that is generally used in the production of printed wiring boards, the support 30 and the film-like substrate 11 are strongly bonded (fused) to each other in the outer peripheral region 8 by hot pressing at about 200 ℃ for about 1 hour.

In the laminate 100, since the film-like base material 11 is bonded and fixed to the outer peripheral region 8 of the rigid support 30, the handling properties in processing such as patterning of a conductor layer (formation of a circuit) provided on the surface of the film-like base material 11 (the surface not in contact with the release sheet 21) and formation of an insulating layer are excellent.

In the manufacturing process of a printed wiring board, a chemical solution is used for a desmear process, a conductor layer is formed by wet plating, a conductor layer is patterned by etching, and an insulating layer such as a resist layer is developed. In the laminate 100, the support 30 and the film-like substrate 11 are bonded and fixed to each other in the outer peripheral region 8, and therefore, when the chemical solution treatment is performed by spraying or dipping, the chemical solution can be prevented from entering the region 7 in the center portion in the plane from the side surface of the laminate 100. Therefore, peeling at the lamination interface between the release sheet 21 and the film-like base material 11 due to the immersion of the chemical solution can be suppressed. Further, since the contact of the chemical solution with the release sheet 21 is suppressed, the heat-resistant film and the adhesive layer constituting the release sheet 21 can be prevented from being corroded by the chemical solution. Therefore, the peeling at the lamination interface can be suppressed, and the contamination of the chemical solution due to the mixing of the dissolved matter of the constituent material of the release sheet 21 and the like can be prevented.

In the region 7 in the central portion in the plane of the laminate 100, the release sheet 21 is disposed between the support 30 and the film-shaped substrate 11, and therefore, even when the adhesive material of the support 30 melts or softens due to hot pressing or the like, the adhesive material does not adhere to the film-shaped substrate 11. Therefore, after processing such as circuit formation and insulating layer formation is performed in a laminated state, the release sheet 21 can be easily peeled from the film-like substrate 11.

From the viewpoint of improving the handleability in the steps of forming a circuit, forming an insulating layer, and the like, it is preferable that: in the laminate 100, the support 30 and the film-shaped substrate 11 are bonded to each other in the outer peripheral region 8, and the film-shaped substrate 11 is closely laminated on the support 30 in the region 7 where the release sheet 21 is provided. For example, if the release sheet 21 has adhesion to the support 30 and the film-like substrate 11, the film-like substrate 11 is in an adhesion state on the support 30 with the release sheet 21 interposed therebetween in the section 7.

As shown in fig. 3, the opening 5 is provided in the release sheet 21, and the support 30 can be in contact with the film-like substrate 11 in a region where the opening 5 is provided. In the region where the opening 5 is provided, the support 30 and the film-like substrate 11 are brought into an adhered state in the same manner as in the outer peripheral region 8, and therefore, the film-like substrate 11 is also fixed to the support 30 in the region 7, and the handleability during processing can be improved. In particular, when the area of the laminate 101 (the area of the release sheet) is large, or when the adhesion of the release sheet 21 to the film-shaped substrate 11 is low, it is useful to bring the support 30 and the film-shaped substrate into an adhered state through the opening 5 provided in the release sheet 21.

When the opening 5 is provided in the release sheet 21, the shape and size of the opening, the number of openings, and the like are not particularly limited. In the case where the size of the opening 5 is largeIn some cases, since the adhesive area between the support 30 and the film-like substrate 11 is large, it may be difficult to separate the film-like substrate 11 from the laminate after processing such as circuit formation. Therefore, the area of 1 opening is preferably 1000mm²Hereinafter, more preferably 500mm²Hereinafter, more preferably 300mm²May be 100mm or less²Below or 50mm²The following. On the other hand, from the viewpoint of fixing the film-like substrate 11 to the support 30 by the opening forming portion, the area of 1 opening is preferably 1mm²Above, more preferably 5mm²The above. The area ratio (aperture ratio) of the aperture-formed portion in the release sheet 21 is preferably 10% or less, more preferably 5% or less, and further preferably 3% or less. The aperture ratio may be 0.1% or more, 0.3% or more, or 0.5% or more.

As shown in fig. 4, the laminate 102 may be formed by laminating the release sheet 21 and the film-like substrate 11 on one main surface of the support 30 and laminating the release sheet 22 and the film-like substrate 12 on the other main surface of the support 30. Since the processing of 2 film-like substrates 11 and 12 can be performed using 1 laminate 102 by laminating the release sheet and the film-like substrate on both surfaces of 1 support, respectively, the material utilization efficiency and the production efficiency can be expected to be improved. Since both main surfaces of the support 30 are covered with the film-like base material, contamination of the process can be prevented even when an adhesive material such as a prepreg is used as the support.

As shown in fig. 5, the release sheet 21 and the film-like substrate 11 may be laminated on one principal surface of the support 30, and the protective sheet 42 may be laminated on the other principal surface so as to cover the entire surface of the support 30. The protective sheet 42 may protrude outward from the outer peripheral end of the support 30. In the laminate 103, since one main surface of the support 30 is covered with the film-like substrate 11 and the other main surface is covered with the protective sheet 42, even when a material having adhesiveness such as a prepreg is used as the support, contamination in the process can be prevented.

As the protective sheet 42, a protective sheet having excellent heat resistance and chemical resistance and capable of adhering to the support 30 is used. The protective sheet 42 may be rigid or flexible. Examples of the material of the protective sheet 42 include glass and a resin material. As the resin material, resin materials exemplified as a material of an insulating resin film of the film-shaped substrate 11 and a material of a heat-resistant resin film of the release sheet 21 are suitably used.

[ production of printed Circuit Board ]

The laminate is applicable to the production of a printed wiring board provided with a circuit formed of a patterned metal conductor on one main surface or both main surfaces of an insulating resin film contained in a film-like substrate. Examples of the printed circuit board having a circuit provided on the main surface of the insulating resin film include a multilayer printed circuit board, a flexible rigid wiring board, a single-sided flexible printed circuit board, and a double-sided flexible printed circuit board.

In a process for manufacturing a printed wiring board using a laminate, a circuit is formed on an insulating resin film of a film-shaped base material (first circuit forming step). In the laminate, the film-like base material 11 is laminated on the rigid support 30 with the release sheet 21 interposed therebetween, and since the laminate has rigidity, a circuit can be formed using a device for handling the rigid base material. Therefore, a narrow pitch circuit equivalent to the circuit of the rigid printed wiring board can be formed on the main surface of the flexible insulating resin film. After forming a circuit on the insulating resin film, the film-like substrate 11 (insulating resin film provided with the circuit) is separated from the support 30 and the release sheet 21 (separation step).

When the film-like substrate 11 includes a conductor layer on an insulating resin film, a circuit is formed by a subtractive method, an additive method, or the like using the conductor layer of the film-like substrate. A conductor layer may be formed on a conductor layer provided in advance on the film-like substrate 11 by electrolytic plating or the like. When the film-like substrate 11 is formed of an insulating resin film and does not include a conductor layer, a conductor layer is formed on a principal surface of the insulating resin film, and a circuit is formed by a subtractive method, an additive method, or the like.

The outline of each step in the production of the printed wiring board will be described below.

< conductive layer Forming Process >

When no conductor layer is provided on the first main surface (main surface on the opposite side to the release sheet 21) of the film-like substrate 11, the conductor layer is formed on the insulating resin film by electroless plating. The conductive layer may be formed by attaching a metal foil such as a copper foil to the insulating resin film. When the film-shaped substrate 11 has a conductor layer, the conductor layer does not need to be formed, but may be formed by electrolytic plating or the like on a conductor layer provided in advance on the insulating resin film. When a hole is formed in the film-like substrate 11, a conductor may be formed by depositing a metal on the wall surface of the hole in addition to the first main surface of the film-like substrate 11. The film-like substrate may be subjected to a desmear treatment as necessary after the film-like substrate is perforated.

Examples of the electroless plating include wet electroless plating, sputtering, vapor deposition, ion plating, and CVD. The type of electroless plating may be selected as appropriate depending on compatibility with the film-like substrate, specifications of the printed wiring board, and the like. In consideration of the general printed circuit board manufacturing process and equipment, wet electroless copper plating is preferable. Examples of the metal species deposited by electrolytic plating include copper, gold, silver, zinc, nickel, chromium, and various alloys (e.g., solder, tin-silver, tin-zinc, etc.). Copper is generally used in the manufacture of printed circuit boards and may be preferred. The thickness of the conductor layer is not particularly limited, and is set in accordance with the specification of the printed wiring board or the like.

< Circuit Forming Process >

A circuit is formed on the insulating resin film by a conductor layer provided in advance on the film-shaped substrate 11 or a conductor layer formed in the above-described conductor layer forming step. For example, a predetermined portion to be a circuit is selectively covered with a resist, and a conductor layer in a region not covered with the resist is dissolved with a chemical solution (etching solution), thereby forming a circuit (subtractive method). A circuit can also be formed by selectively covering a predetermined portion to be a non-circuit forming portion (a space between a circuit) with a plating resist, performing pattern plating by electrolytic plating using a conductor layer as a power supply layer, then peeling off the resist, and removing the exposed power supply layer by etching (semi-additive method). The method of forming the circuit may be selected appropriately according to the specification of the printed wiring board to be manufactured.

In the formation of circuits, various chemical solutions are used for the formation of conductor layers by wet methods such as wet chemical plating and electrolytic plating, the development in the patterning of resist layers, the patterning of conductor layers by etching, the peeling of resist layers, the etching of power feed layers after pattern plating, and the like. When these chemical solutions are impregnated into the lamination interface between the film-shaped substrate and the release sheet, the film-shaped substrate may be peeled from the laminate. Further, in the case where the release sheet is provided with an adhesive layer, there is a concern about contamination of the chemical solution due to mixing of the adhesive dissolved in the chemical solution.

In the laminate, the support 30 is bonded to the film-like substrate 11 at the outer periphery of the release sheet 21, and the outer peripheral end (end face) 2 of the release sheet 21 is not exposed. Therefore, the chemical solution is prevented from entering the end face of the release sheet 21 and the lamination interface between the release sheet 21 and the film-like substrate 11, and peeling of the film-like substrate and contamination of the process in a process such as circuit formation can be prevented.

< separation step >

After forming the circuit on the first principal surface of the insulating resin film, the film-like substrate 11 (insulating resin film provided with the circuit) is separated from the laminate. The film-like substrate 11 and the support 30 can be separated by cutting out the region 8 at the outer peripheral edge portion where they are bonded. For example, the outer peripheral edge portion is cut off by cutting the laminate along the line C1, the line C2, the line C3, and the line C4 in fig. 2. The cutting method may be appropriately selected depending on the material of the support 30 and the film-like base material 11, and milling, die processing (punching), and the like may be applied.

At the time of separation, the outer peripheral edge portion need not be completely cut. For example, the film-like substrate may be cut by half-cutting along the outer peripheral edge. Further, the film-like substrate 11 may be peeled and separated from the portion where the film-like substrate 11 and the support are bonded.

Since the film-like base material 11 and the release sheet 21 have a low adhesive strength at the interface, they can be easily peeled off at the lamination interface therebetween, and contamination of the second main surface (main surface on the opposite side to the circuit-formed surface) of the film-like base material 11 by the release sheet 21 does not easily occur.

By the above process, a printed wiring board in which the first circuit is formed on the first main surface of the insulating resin film can be obtained. The second circuit may be formed by laminating another insulating layer on the first main surface of the insulating resin film on which the first circuit is formed, thereby forming a second circuit. After the film-like base material is separated from the laminate, a third circuit may be formed on the second main surface of the film-like base material (insulating resin film).

< multilayering >

Multilayering can be performed according to the general method of printed circuit boards. For example, after an insulating layer is formed on a first main surface of an insulating resin film provided with a first circuit and a hole penetrating the insulating layer is formed, a second circuit is formed on the insulating layer. By repeating the formation of the insulating layer on the circuit, the formation of the hole, and the formation of the circuit, a multilayer structure of 3 or more layers can be obtained.

(formation of insulating layer)

Examples of the material of the insulating layer include a prepreg, a bonding sheet made of a thermosetting resin, an ink material of a thermosetting or photocurable resin, a thermosetting build-up film, and a laminate having an adhesive layer provided on a surface of a single-sided copper-clad laminate on which a copper layer is not formed. Prepregs, sheets, and film-like materials may be laminated by hot pressing, roll lamination, vacuum lamination, or the like. The ink-like material may be formed into an insulating layer by a printing method, a curtain coating method, or the like. When the insulating layer is formed, metal foils may be simultaneously stacked.

(opening and conductor formation)

The hole formation to the insulating layer is performed by, for example, laser drilling, mechanical drilling, or the like. The opening of the insulating layer may be performed by plasma irradiation, chemical etching, or the like. The holes may be formed through the film-like substrate in addition to the insulating layer, or may be formed through 2 or more insulating layers.

After the hole is formed, the wall surface of the hole is made conductive. The conductimerization is performed by, for example, electroless plating. The electroless plating may be wet plating or dry plating (PVD method or CVD method), and is appropriately selected depending on the material and thickness of the insulating layer, the specification of the printed wiring board, and the like. In consideration of the general printed circuit board manufacturing process and equipment, wet electroless copper plating is preferable. The conductive paste may be printed in the holes to be conductive.

(formation of conductive layer)

The method of providing the conductor layer for forming the second circuit on the insulating layer is not particularly limited, and may be appropriately selected from electroless plating, electrolytic plating, a combination of electroless plating and electrolytic plating, and the like. In consideration of the general printed circuit board manufacturing process and equipment, wet electroless copper plating is preferable. When a conductive layer is formed on an insulating layer, a metal can be deposited on the wall surface of a hole provided in the insulating layer to form a conductor. When a laminate having a conductor layer on the surface of an insulating layer, for example, a single-sided copper-clad laminate, or a laminate in which metal foils are laminated with a prepreg, a bonding sheet, or the like interposed therebetween is used, the second circuit can be formed using the conductor layer of the laminate.

(formation of second Circuit)

A second circuit is formed on the insulating layer using a conductor layer provided on the insulating layer. The method of forming the second circuit is not particularly limited, and a subtractive method, a semi-additive method, or the like can be applied in the same manner as the formation of the first circuit.

The formation of a plurality of layers on the first main surface of the film-like substrate may be performed at any time before or after the separation step. When the multilayer structure is formed before the separation step, the second circuit may be formed using a device for processing a rigid substrate, as in the first circuit forming step. When a rigid material is used as the insulating layer, since the base material has rigidity even after being separated from the support 30, the second circuit can be formed using a device for processing a rigid base material as in the first circuit forming step even after the separating step. In the middle of multilayering, separation from the support 30 and the release sheet 21 can be performed. For example, after a rigid insulating layer is provided behind the first main surface of the film-like substrate 11 to secure rigidity, a separation step may be performed before the hole opening and circuit formation.

< third Circuit Forming Process >

After the release sheet 21 is peeled from the second main surface of the film-like substrate 11 in the separating step, a third circuit can be formed on the second main surface of the film-like substrate 11. The method of forming the third circuit can be carried out by the same appropriate method as the formation of the first circuit and the second circuit described above. For example, a circuit is formed by forming a conductor layer on the second main surface of the insulating resin film and patterning the conductor layer. The conductor layer may be used as a power supply layer, and a circuit may be formed by pattern plating. When a conductive layer is provided in advance on the second main surface of the film-like substrate 11, a third circuit can be formed using the conductive layer.

Before or after the third circuit is formed, a hole may be formed to penetrate the film-shaped substrate 11 (insulating resin film). When the insulating layer is formed on the first main surface of the insulating resin film and the insulating resin film is multilayered, the hole may be formed so as to penetrate the insulating layer in addition to the film-like substrate 11. After the hole is opened, the conductor is formed by electroless plating, printing of conductive paste, or the like.

In the case where the insulating layer is formed on the first main surface of the insulating resin film and the third circuit is multilayered before the third circuit is formed, since the substrate has rigidity, the third circuit can be formed using an apparatus for processing a rigid substrate in the same manner as in the first circuit forming step.

After the film-shaped substrate 11 (insulating resin film) on which the first circuit has been formed is separated from the support 30 and the release sheet 21, a rigid support may be laminated on the first main surface (first circuit forming surface) side of the film-shaped substrate 21 to form a laminate. By using this laminate, a device for processing a rigid substrate can be applied to the formation of the third circuit on the second main surface, as in the case of the formation of the first circuit on the first main surface, and therefore, the pitch of the circuit can be easily narrowed.

Similarly to the formation of the laminate 100, a release sheet may be disposed between the film-shaped base and the support, and the laminate may be formed by hot pressing or the like in a state where the film-shaped base and the support protrude outward from the outer peripheral end of the release sheet. By forming such a laminate, peeling due to the chemical solution entering the laminate interface and contamination of the chemical solution due to the dissolved matter can be prevented in the formation of the third circuit as well as in the formation of the first circuit.

If the first circuit is formed on the first main surface using the laminate 100 laminated such that the second main surface of the film-like base material is on the support side, and after the separation step, the laminate is formed such that the first main surface of the film-like base material is on the support side, and the third circuit is formed on the second main surface, a double-sided flexible printed board having circuits on both surfaces of the insulating resin film can also be formed.

Examples

The present invention will be described more specifically below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[ example 1]

FR-4 prepreg "GEA-67N" (thickness 150 μm) manufactured by Hitachi chemical Co., Ltd was used as a support, a heat-resistant micro-adhesive film ("LIOELMLE 951" manufactured by TOYO-CHEM Co., Ltd.) in which an acrylic micro-adhesive layer having a thickness of 10 μm was provided on one surface of a polyethylene terephthalate (PET) film having a thickness of 50 μm was used as a release sheet, and a double-sided copper-clad laminate in which an electrolytic copper foil "HD 2" manufactured by Futian Metal Co., Ltd was thermally laminated on a polyimide film ("PIXIO FRS 25" manufactured by KANEKA Co., Ltd.) having thermoplastic polyimide adhesive layers on both surfaces of a polyimide core layer and a total thickness of 25 μm was used as a film-like base. The support was cut into a size of 120mm × 120mm, the release sheet was cut into a size of 100mm × 100mm, the film-shaped substrate was cut into a size of 140mm × 140mm, the positional relationship was adjusted so that the support protruded from the outer periphery of the release sheet with a width of 10mm and the film-shaped substrate protruded from the outer periphery of the release sheet with a width of 20mm, and the support, the release sheet, and the film-shaped substrate were stacked in this order. The release sheet is disposed so that the adhesive layer forming surface is in contact with the film-like substrate.

The laminate was pressed at 180 ℃ under 3MPa for 60 minutes by using a hot press apparatus to obtain a laminate. The resulting laminate was the following: in the region where the release sheet is arranged, the release sheet is in close contact with the film-shaped base material, and the film-shaped base material is fixed to the support body with the release sheet interposed therebetween, and has sufficient rigidity to be handled by the rigid printed wiring board manufacturing apparatus. The support and the film-like base material were firmly bonded to each other in a frame-like region 10mm wide outside the outer periphery of the release sheet.

The laminate was subjected to desmear treatment under the conditions shown in table 1 and wet electroless copper plating treatment under the conditions shown in table 2. A copper plating film is formed on a copper foil of a film-like substrate. Further, the outer periphery of the laminate was not attacked by the chemical solution, and no problems such as delamination were observed.

< decontamination treatment >

[ Table 1]

< Wet electroless copper plating treatment >

[ Table 2]

When the frame-like adhesive portion on the outer periphery of the laminate was cut with scissors, the laminate could be peeled off well at the interface between the release sheet and the film-like base material, and no problem such as contamination was observed at the contact surface between the film-like base material and the release sheet.

[ example 2]

A laminate was formed in the same manner as in example 1 except that the release sheet was changed to a fluorine-based resin film (AFREX 25N NT, manufactured by Asahi glass company) having a thickness of 25 μm, and desmear treatment and wet electroless copper plating treatment were performed. In example 2 as well, a copper plating film was formed on the copper foil of the film-like base material in the same manner as in example 1, and the outer periphery of the laminate was not attacked by the chemical solution, and no problem such as interlayer peeling was observed. When the frame-like adhesive portion on the outer periphery of the laminate was cut with scissors, the laminate could be satisfactorily peeled off at the interface between the release sheet and the film-like substrate, and no trouble such as contamination was observed at the contact surface between the film-like substrate and the release sheet.

Comparative example 1

A laminate was formed in the same manner as in example 1, except that the dimensions of the release sheet were changed to 120mm × 120mm (the same dimensions as the support), and the release sheet was disposed so as to cover the entire surface of the support. In the obtained laminate, the release sheet is firmly bonded to the entire surface of the support, and the release sheet is in close contact with the film-like base material. When the laminate was subjected to desmear treatment and wet electroless copper plating treatment in the same manner as in example 1, the adhesive of the release sheet was eroded by the chemical solution at and near the outer periphery of the release sheet, and the film-like base material was peeled from the release sheet. It can be considered that: in this example, the adhesive eroded by the chemical solution is mixed into the chemical solution, whereby contamination of the chemical solution occurs.

Comparative example 2

A laminate was formed in the same manner as in example 2, except that the dimensions of the release sheet were changed to 120mm × 120mm (the same dimensions as the support), and the release sheet was disposed so as to cover the entire surface of the support. In the obtained laminate, the release sheet was firmly bonded to the entire surface of the support, but the adhesion between the release sheet and the copper foil of the film-like substrate was insufficient. When the multilayer body was subjected to desmutting treatment and wet electroless copper plating treatment in the same manner as in examples 1 and 2, peeling occurred from the periphery. This is presumably caused by the chemical solution entering the interface between the release sheet and the film-like substrate.

From the results of the above examples and comparative examples, it can be seen that: by using a laminate in which the dimensions of the support (prepreg) and the film-like substrate (copper-clad laminate) are larger than the dimensions of the release sheet, and the support and the film-like substrate are bonded to each other in the frame-like region on the outer periphery, the penetration of the chemical solution into the lamination interface in the production process of the printed wiring board is blocked, and the peeling of the interface and the contamination of the chemical solution can be prevented.

Description of the reference numerals

11. 12 film-like base material

21. 22 Release sheet

30 support

42 protective sheet

100. 101, 102, 103 laminate

Claims

1. A laminate comprising, laminated in this order: a rigid support having a first main surface and a second main surface, a release sheet having a first main surface and a second main surface, and a flexible film-like substrate having a first main surface and a second main surface,

a first main surface of the support body is in contact with a second main surface of the release sheet, the first main surface of the release sheet is in contact with a second main surface of the film-like substrate,

the film-like substrate comprises a flexible insulating resin film,

the outer periphery of the support body protrudes outward from the outer periphery of the release sheet,

the outer periphery of the film-like base material protrudes outward from the outer periphery of the release sheet,

the first main surface of the support body and the second main surface of the film-like base material are bonded to each other outside the outer periphery of the release sheet.

2. The laminate according to claim 1, wherein the release sheet is provided with an opening, and the first main surface of the support body and the second main surface of the film-like base material are bonded to each other at a portion where the release sheet is provided with the opening.

3. The laminate according to claim 1 or 2, wherein an outer periphery of the film-like base protrudes outward from an outer periphery of the support.

4. A stack according to any one of claims 1 to 3, wherein the support is a prepreg.

5. The laminate according to any one of claims 1 to 4, wherein the insulating resin film is a polyimide film.

6. The laminate according to any one of claims 1 to 5, wherein the film-like substrate is formed of the insulating resin film.

7. The laminate according to any one of claims 1 to 5, wherein the film-like base material comprises a metal conductor layer on at least one principal surface of the insulating resin film.

8. A method for producing a laminate according to any one of claims 1 to 7,

the support and the film-shaped substrate are bonded to each other in a region outside the outer periphery of the release sheet by hot-pressing a laminate in which the release sheet and the film-shaped substrate are arranged in this order on the first main surface of the support.

9. A method for manufacturing a printed wiring board having a circuit formed of a metal conductor on an insulating resin film, comprising the steps of:

a first circuit forming step: forming a first circuit on a first main surface of an insulating resin film of the laminate according to any one of claims 1 to 7; and

a separation process: the insulating resin film provided with the first circuit is separated from the support body and the release sheet.

10. The method for manufacturing a printed wiring board according to claim 9, comprising a multilayering step of: an insulating layer is provided to cover the first main surface of the insulating resin film and the first circuit, and a second circuit is formed on the insulating layer.

11. The method for manufacturing a printed wiring board according to claim 9 or 10, comprising a third circuit forming step of forming a third circuit on the second main surface of the insulating resin film after the separating step.

12. The method of manufacturing a printed circuit board according to any one of claims 9 to 11, wherein in the first circuit forming step, a circuit is formed by etching the metal conductor layer on the first main surface of the insulating resin film.

13. The method of manufacturing a printed circuit board according to any one of claims 9 to 11, wherein in the first circuit forming step, a circuit is formed on the first main surface of the insulating resin film by pattern plating.

14. The method of manufacturing a printed circuit board according to any one of claims 9 to 13, wherein a metal conductor layer is formed on the first main surface of the insulating resin film by wet or dry electroless plating before the first circuit forming step.

15. The method for manufacturing a printed circuit board according to any one of claims 9 to 14, wherein in the separation step, an outer peripheral edge portion of the laminate to which the support and the film-like base material are bonded is cut out.