JP2010253854A - Multilayered release film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multilayered release film which is excellent in wrinkle prevention and can control flowing out of an adhesive agent from a coverlay film or the like, and to provide a method of manufacturing a print board using the multilayered release film. <P>SOLUTION: The multilayered release film includes an intermediate layer and two surface layers laminated on both surfaces of the intermediate layer wherein the thickness of one of two surface layers is ≥5 μm and <25 μm, and the thickness of another one is ≥25 μm and <50 μm. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to a multilayer release film that has excellent wrinkle resistance and can suppress the flow of an adhesive from a coverlay film or the like. The present invention also relates to a method for producing a printed circuit board using the multilayer release film.

In the production of a printed circuit board such as a flexible printed circuit board, a cover lay film or a reinforcing plate is bonded to a printed circuit board main body having a circuit on its surface via a thermosetting adhesive or a thermosetting adhesive sheet by hot pressing. It is widely practiced to protect the circuit surface of the body. In such hot press molding, a release film is used in the middle to prevent the cover lay film or the reinforcing plate and the hot press plate from adhering to each other. Such a release film is required to have, for example, heat resistance capable of withstanding hot press molding and performance such as release properties with respect to a printed board or a hot press plate.

In recent years, since the use of thinner coverlay films has become the mainstream, the wrinkles generated in the release film are likely to be transferred to the coverlay film, leading to deterioration in the yield of printed circuit boards in hot press molding. Yes.

For example, Patent Documents 1 to 4 disclose a method for imparting a concavo-convex shape to the surface of a release film as a method for suppressing generation of wrinkles in the release film. For example, Patent Document 1 discloses that grooves having a surface roughness (Ra) of the top flat portion of 0.25 to 15 μm and an average depth of 10 to 70 μm and an average width of 0.1 to 3 mm on the surface are averaged. Heat having at least one surface provided with a pitch of 0.5 to 30 mm, a total thickness of 30 to 200 μm, and an average depth of the groove in a range of 10 to 70% of the total thickness A surface-roughened film made of a plastic resin is disclosed.

On the other hand, in hot press molding, it is also a problem that an adhesive such as a coverlay film flows out to the electrode part of the printed board. The adhesive that contaminates the electrode part may be an obstacle such as plating. Furthermore, in recent years, circuit patterns of printed circuit boards such as flexible printed circuit boards have become finer, so the influence of the adhesive that has flowed out on the electrodes has increased, and it has been necessary to improve the yield in hot press molding. Controlling the flow of the agent is an increasingly important issue.

JP 2007-83459 A Japanese Patent Laid-Open No. 6-23840 JP-A-3-61011 JP-A-2-238911

However, in order to suppress the generation of wrinkles in the release film, it is considered preferable to increase the thickness of the release film in addition to providing the surface with irregularities as described above, whereas the coverlay film In order to suppress the flow-out of the adhesive from the like, it is considered preferable to improve the followability to the circuit surface by thinning the release film. Therefore, even in the case of a printed circuit board such as a flexible printed circuit board having a fine circuit pattern, it is possible to perform hot press molding well while suppressing the generation of wrinkles and suppressing the flow of the adhesive from the coverlay film or the like. It was difficult to obtain a release film.

An object of this invention is to provide the multilayer release film which is excellent in wrinkle resistance and can suppress the flow-out of the adhesive from a coverlay film or the like. Another object of the present invention is to provide a method for producing a printed circuit board using the multilayer release film.

The present invention is a multilayer release film having an intermediate layer and two surface layers laminated on both sides of the intermediate layer, the two surface layers having a thickness of 5 μm or more and less than 25 μm, and The other is a multilayer release film having a thickness of 25 μm or more and less than 50 μm.
The present invention is described in detail below.

The inventors use a multilayer release film having an intermediate layer and two surface layers laminated on both sides of the intermediate layer, and each of the two surface layers having a thickness within a predetermined range. Thus, in the production of a printed circuit board such as a flexible printed circuit board, it has been found that hot press molding can be performed satisfactorily while suppressing the generation of wrinkles and suppressing the flow of adhesive from a coverlay film or the like. It came to complete.

The multilayer release film of the present invention has an intermediate layer and two surface layers laminated on both surfaces of the intermediate layer.
One of the two surface layers has a thickness of 5 μm or more and less than 25 μm, and the other has a thickness of 25 μm or more and less than 50 μm. In the present specification, the surface layer having a thickness of 5 μm or more and less than 25 μm is also referred to as “surface layer 1”, and the surface layer having a thickness of 25 μm or more and less than 50 μm is also referred to as “surface layer 2”.

In hot press molding when manufacturing a printed circuit board such as a flexible printed circuit board, in order to suppress the generation of wrinkles in the release film and to suppress the transfer of wrinkles to the coverlay film, the release film must be thickened. Is considered preferable. On the other hand, in order to suppress the flow of the adhesive from the coverlay film or the like, it is preferable to improve the followability to the circuit surface by thinning the release film. Therefore, it has been difficult to achieve both suppression of wrinkle generation and suppression of adhesive flow-out.
In contrast, the multilayer release film of the present invention has a surface layer 1 having a thickness of 5 μm or more and less than 25 μm, an intermediate layer, and a surface layer 2 having a thickness of 25 μm or more and less than 50 μm. The thicknesses of the two surface layers via are different. By having such a structure, when manufacturing a printed circuit board such as a flexible printed circuit board using the multilayer release film of the present invention, the surface layer 1 is on the circuit surface side of the printed circuit board body, and the surface layer 2 is hot-pressed. By performing the hot press molding so as to be on the plate side, it is possible to suppress the generation of wrinkles and suppress the flow of the adhesive from the coverlay film or the like, thereby improving the yield in the hot press molding.

The surface layer 1 has a thickness of 5 μm or more and less than 25 μm. When the thickness of the surface layer 1 is less than 5 μm, the thickness is too thin and the strength is impaired. Therefore, in the hot press molding using the obtained multilayer release film or the peeling process of the multilayer release film, the surface layer Problems such as destruction of 1 occur. When the thickness of the surface layer 1 is 25 μm or more, in the hot press molding using the obtained multilayer release film, the followability of the multilayer release film to the circuit surface is reduced, and the adhesive from the coverlay film or the like It becomes difficult to suppress the outflow. The thickness of the surface layer 1 is preferably 10 μm or more and 20 μm or less.

The surface layer 2 has a thickness of 25 μm or more and less than 50 μm. When the thickness of the surface layer 2 is less than 25 μm, the wrinkle resistance of the obtained multilayer release film is lowered. If the thickness of the surface layer 2 is 50 μm or more, the cost will be increased to improve performance more than necessary. The thickness of the surface layer 2 is preferably 25 μm or more and 40 μm or less.

The resin which comprises the said surface layer 1 and the said surface layer 2 is not specifically limited, For example, crystalline aromatic polyester resin is mentioned.
The crystalline aromatic polyester resin has a preferred lower limit of the melting point measured using a differential scanning calorimeter of 200 ° C. Since the hot press molding is usually performed at less than 200 ° C., the surface layer 1 and / or the surface layer 2 are melted in the hot press molding using the resulting multilayer release film by using a resin having a high melting point. It can have releasability without doing and can prevent the surface layer 1 and / or the surface layer 2 from being destroyed. When the melting point is less than 200 ° C., the surface layer 1 and / or the surface layer 2 may melt in the hot press molding using the resulting multilayer release film, and the heat resistance of the multilayer release film may be lowered. A more preferable lower limit of the melting point of the crystalline aromatic polyester resin measured using a differential scanning calorimeter is 220 ° C.

Further, the upper limit of the melting point of the crystalline aromatic polyester resin measured using a differential scanning calorimeter is not particularly limited, but the crystalline aromatic polyester resin is melt-molded to form the surface layer 1 and / or the surface layer 2. When obtaining, a preferable upper limit is 400 ° C. from the viewpoint of the cost of the heating equipment.
In addition, the said differential scanning calorimeter is not specifically limited, For example, DSC 2920 (made by TA Instruments) etc. are mentioned.

The crystalline aromatic polyester resin having a melting point of 200 ° C. or higher measured using the differential scanning calorimeter is not particularly limited. For example, polyethylene terephthalate, polybutylene terephthalate, polyhexamethylene terephthalate, polyethylene naphthalate, polybutylene Examples thereof include phthalate and butanediol terephthalate polytetramethylene glycol copolymers. These may be used independently and 2 or more types may be used together. Of these, polybutylene terephthalate is preferably used because it is excellent in non-contamination and crystallinity.

The surface layer 1 and the surface layer 2 may contain a stabilizer.
The stabilizer is not particularly limited. For example, 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, 3,9-bis { 2- [3- (3-tert-butyl-4-hydroxy-5-methylphenyl) -propionyloxy] -1,1-dimethylethyl} -2,4,8,10-tetraoxaspiro [5,5 Hindered phenolic antioxidants such as undecane, tris (2,4-di-t-butylphenyl) phosphite, trilauryl phosphite, 2-t-butyl-α- (3-t-butyl-4) -Hydroxyphenyl) -p-cumenylbis (p-nonylphenyl) phosphite, dimyristyl 3,3'-thiodipropionate, distearyl 3,3'-thiodipropionate, pentaerythryl tetrakis And heat stabilizers such as ditridecyl 3,3′-thiodipropionate.

The surface layer 1 and the surface layer 2 may contain additives such as fibers, inorganic fillers, flame retardants, ultraviolet absorbers, antistatic agents, inorganic substances, higher fatty acid salts, and the like as long as the effects of the present invention are not impaired. Good.

The fibers are not particularly limited, and examples thereof include glass fibers, carbon fibers, boron fibers, silicon carbide fibers, alumina fibers, amorphous fibers, inorganic fibers such as silicon-titanium-carbon fibers, and organic fibers such as aramid fibers. Can be mentioned.

The inorganic filler is not particularly limited, and examples thereof include calcium carbonate, titanium oxide, mica and talc.
The flame retardant is not particularly limited, and examples thereof include hexabromocyclododecane, tris- (2,3-dichloropropyl) phosphate, pentabromophenyl allyl ether, and the like.

The ultraviolet absorber is not particularly limited. For example, pt-butylphenyl salicylate, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-2′-carboxybenzophenone, 2,4,5-tri And hydroxybutyrophenone.
The antistatic agent is not particularly limited, and examples thereof include N, N-bis (hydroxyethyl) alkylamine, alkylallyl sulfonate, and alkyl sulfonate.

The inorganic material is not particularly limited, and examples thereof include barium sulfate, alumina, and silicon oxide.
The higher fatty acid salt is not particularly limited, and examples thereof include sodium stearate, barium stearate, and sodium palmitate.

The surface layer 1 and the surface layer 2 may contain a thermoplastic resin and a rubber component in order to modify the properties.
The thermoplastic resin is not particularly limited, and examples thereof include polyolefin, modified polyolefin, polystyrene, polyvinyl chloride, polyamide, polycarbonate, polysulfone, and polyester.

The rubber component is not particularly limited. For example, natural rubber, styrene-butadiene copolymer, polybutadiene, polyisoprene, acrylonitrile-butadiene copolymer, ethylene-propylene copolymer (EPM, EPDM), polychloroprene, butyl rubber. Acrylic rubber, silicone rubber, urethane rubber, olefin thermoplastic elastomer, styrene thermoplastic elastomer, vinyl chloride thermoplastic elastomer, ester thermoplastic elastomer, amide thermoplastic elastomer, and the like.

The surface layer 1 and the surface layer 2 may contain an inorganic compound having a large aspect ratio. By including such an inorganic compound having a large aspect ratio, the release property at a high temperature of the obtained multilayer release film is improved, and additives and low molecular weight substances contained in the multilayer release film are transferred to the film surface. Bleed-out can be suppressed, and cleanliness during hot press molding is improved.
The inorganic compound having a large aspect ratio is not particularly limited, and examples thereof include layered silicates such as clay and layered double hydrates such as hydrotalcite.

As long as the surface layer 1 and the surface layer 2 satisfy the above-described thickness, the resin that is the main component and the other additive components described above may contain the same constituent components, and may contain different constituent components. It may be.

The surface layer 1 is a method according to JIS B0601: 2001, using a stylus having a tip radius of 2 μm and a conical taper angle of 60 °, a measuring force of 0.75 mN, a cutoff value λs = 2.5 μm, λc = 0. The average length RSm of the roughness curve element measured under the condition of 8 mm is preferably 300 μm or less. When the average length RSm of the roughness curve element of the surface layer 1 satisfies the above range, the obtained multilayer release film is subjected to hot press molding so that the surface layer 1 is on the circuit surface side of the printed circuit board body. In addition, excellent wrinkle resistance can be exhibited.
The surface layer 1 is a method according to JIS B0601: 2001, using a stylus having a tip radius of 2 μm and a conical taper angle of 60 °, a measuring force of 0.75 mN, a cutoff value λs = 2.5 μm, λc = 0. The average length RSm of the roughness curve element measured under the condition of 8 mm is more preferably 200 μm or less.

In addition, the smaller the average length RSm of the roughness curve element of the surface layer 1, the higher the anti-wrinkle property of the multilayer release film, but if it is too small, the release property of the multilayer release film may be lowered. Therefore, in order to ensure the releasability of the obtained multilayer release film, the average length RSm of the roughness curve element of the surface layer 1 is preferably 10 μm or more.

In the surface layer 2, a stylus having a tip radius of 2 μm and a conical taper angle of 60 ° is used in accordance with JIS B0601: 2001, a measuring force of 0.75 mN, a cutoff value λs = 2.5 μm, and λc = 0. The average length RSm of the roughness curve element measured under the condition of 0.8 mm is not particularly limited, but the difference from the average length RSm of the roughness curve element of the surface layer 1 is preferably 100 μm or more. Moreover, it is preferable that the average length RSm of the roughness curve element of the surface layer 1 is smaller than the average length RSm of the roughness curve element of the surface layer 2. By having such a difference, in the obtained multilayer release film, the surface layer 1 and the surface layer 2 have different surface shapes and a difference in surface gloss occurs. Therefore, the surface layer 1 and the surface layer 2 Can be easily distinguished visually.
The average length RSm of the roughness curve element is a lateral parameter in the roughness curve of the uneven shape on the surface of the multilayer release film, and the larger the surface gloss, the smaller the surface gloss. It becomes a mat-shaped surface.

The method for providing the surface layer 1 and the surface layer 2 with an uneven shape so that the surface layer 1 and the surface layer 2 have the average length RSm of the roughness curve element described above is not particularly limited. On the surface of the resin film formed by extruding the intermediate layer and the resin constituting the surface layer 2 from a T-die using an extruder (for example, GM30-28 (screw diameter 30 mm, L / D28), manufactured by GM Engineering). On the other hand, the method of pressing the cooling roll by which the pattern was processed on the surface, and transferring the pattern processed by the surface of the cooling roll to the resin film surface etc. are mentioned.

The cooling roll whose pattern is processed on the surface can be produced, for example, by adjusting the roughness of the smooth portion of the roll after forming a concave pattern on the surface of the smooth roll.
The pattern processed on the surface of the cooling roll is not particularly limited, and examples thereof include a concavo-convex pattern having a single shape, and a concavo-convex pattern having a plurality of shapes in which fine concavo-convex patterns are superimposed on a concavo-convex pattern made of a large blast material. .

The resin which comprises the said intermediate | middle layer is not specifically limited, For example, polyolefin resin is mentioned.
The polyolefin resin is not particularly limited. For example, ethylene-acrylic such as polyethylene, ethylene-vinyl acetate copolymer, ethylene-methyl methacrylate copolymer, ethylene-ethyl acrylate copolymer, ethylene-acrylic acid copolymer, etc. And copolymers of monomer based monomers. These may be used independently and 2 or more types may be used together.

Moreover, the said intermediate | middle layer may contain resin, such as a polystyrene, a polypropylene, a polyvinyl chloride, polyamide, a polycarbonate, a polysulfone, polyester, in the range which does not inhibit the objective of this invention.

Moreover, the said intermediate | middle layer may contain additives, such as a fiber, an inorganic filler, a flame retardant, an ultraviolet absorber, an antistatic agent, an inorganic substance, a higher fatty acid salt similarly to the said surface layer 1 and the said surface layer 2. .

The intermediate layer has a preferred lower limit of the melting point measured using a differential scanning calorimeter of 70 ° C. and a preferred upper limit of 140 ° C. When the melting point is less than 70 ° C., in the hot press molding using the resulting multilayer release film, the function of the intermediate layer, in which the pressure is uniformly applied to the printed circuit board body, may not be sufficiently achieved. Moreover, when the said melting | fusing point is less than 70 degreeC, when an atmospheric temperature will be 50-60 degreeC during storage of the multilayer release film obtained, an intermediate | middle layer may melt | dissolve and it may cause blocking. is there. When the melting point exceeds 140 ° C., in the hot press molding using the resulting multilayer release film, the intermediate layer is not sufficiently softened in the temperature region where the adhesive melts from the coverlay film or the like, and the adhesive flows out. May not be sufficiently suppressed. The upper limit with a more preferable melting | fusing point measured using the differential scanning calorimeter of the said intermediate | middle layer is 120 degreeC.

Further, even when there are two or more kinds of resins constituting the intermediate layer, the preferable lower limit of the melting point measured using the differential scanning calorimeter of the intermediate layer is 70 ° C, and the preferable upper limit is 140 ° C. When the difference between the melting points of at least two kinds of resins constituting the intermediate layer is 15 ° C. or more, the followability of the film is secured by a resin having a relatively low melting point among the resins constituting the intermediate layer, and the intermediate layer The resin flow of the film can be prevented by a resin having a relatively high melting point among the resins constituting the film.
Further, by constituting the intermediate layer with two or more kinds of resins, other physical properties can be imparted to the intermediate layer in addition to the melting point in the above range and the storage elastic modulus in the range described later.

The said intermediate | middle layer has a preferable minimum of 5.0 * 10 < ³ > Pa and a preferable upper limit of 1.0 * 10 < ⁵ > Pa at a storage elastic modulus in 185 degreeC, 100% of strain amount, and 10 rad / s. When the storage elastic modulus is less than 5.0 × 10 ³ Pa, in the case of hot press molding using the resulting multilayer release film, when the intermediate layer exudes at the film end face, the film is peeled off from the hot press plate. In some cases, the intermediate layer cannot withstand high strain due to peeling, causing the cohesive failure, and the intermediate layer exuded from the film may adhere to the hot press plate and remain. When the storage elastic modulus exceeds 1.0 × 10 ⁵ Pa, the formability of the intermediate layer may be lowered. A more preferable lower limit of the storage elastic modulus at 185 ° C., a strain amount of 100%, and 10 rad / s of the intermediate layer is 1.0 × 10 ⁴ Pa, and a more preferable upper limit is 8.0 × 10 ⁴ Pa.

The intermediate layer preferably has a melt flow rate of less than 0.3 g / 10 minutes. When the melt flow rate is 0.3 g / 10 min or more, in the hot press molding using the obtained multilayer release film, the resin oozes out from the film end face, and workability may be lowered.
Although the minimum of the melt flow rate of the said intermediate | middle layer is not specifically limited, 0.1 g / 10min can be mentioned as a minimum of the melt flow rate of the resin now generally available.

Although the thickness of the said intermediate | middle layer is not specifically limited, A preferable minimum is 30 micrometers and a preferable upper limit is 150 micrometers. When the thickness of the intermediate layer is less than 30 μm, the thickness is too thin, and when the resin constituting the intermediate layer softens in the hot press molding using the resulting multilayer release film, the intermediate layer partially exists In some cases, the pressure is not uniformly applied to the printed circuit board body. When the thickness of the intermediate layer exceeds 150 μm, the multilayer release film becomes too strong and the flexibility is impaired, so that the followability may be lowered. In addition, when the thickness of the intermediate layer exceeds 150 μm, it is unnecessarily thick, so in the hot press molding using the resulting multilayer release film, excess portions of the intermediate layer may ooze out from the film end face. There is. The more preferable lower limit of the thickness of the intermediate layer is 60 μm, and the more preferable upper limit is 100 μm.

The multilayer release film of the present invention preferably has a dimensional change rate of 1.5% or less when pressed at 170 ° C. with a load of 3 MPa for 60 minutes. When the dimensional change rate exceeds 1.5%, the circuit pattern of the printed circuit board body may be impaired in hot press molding using the resulting multilayer release film. The dimensional change rate when the multilayer release film of the present invention is pressurized at 170 ° C. with a load of 3 MPa for 60 minutes is more preferably 1.0% or less.
Furthermore, it is preferable that the dimensional change rate in the width direction (hereinafter also referred to as TD) and the length direction (hereinafter also referred to as MD) of the multilayer release film of the present invention is in the same direction and is approximately equivalent. When the vertical and horizontal dimensional changes such that one (for example, MD) contracts and the other (for example, TD) extends are different, the circuit pattern of the printed circuit board main body is damaged in the hot press molding using the resulting multilayer release film. Sometimes.

The method for producing the multilayer release film of the present invention is not particularly limited. For example, the resin film obtained after producing a three-layer resin film comprising the resin constituting the surface layer 1, the intermediate layer, and the surface layer 2 is obtained. The method of giving uneven | corrugated shape to the surface of this by the method using the cooling roll mentioned above, etc. are mentioned.
The method for producing the three-layer resin film is not particularly limited. For example, the film is formed by a water-cooled or air-cooled co-extrusion inflation method, a co-extrusion T-die method, a film to be the surface layer 1, and then the film. An intermediate layer is laminated by extrusion laminating method, then surface layer 2 is dry laminated, surface layer 1 film, intermediate layer film and surface layer 2 film are dry laminated, solvent casting method, heat press Examples include molding methods. Especially, the method of forming into a film by the coextrusion T-die method is suitable from the point which is excellent in thickness control of each layer.

In the solvent casting method, for example, after an anchor layer is undercoated on a film serving as an intermediate layer, a resin composition constituting surface layer 1 or surface layer 2 dissolved in a solvent is applied on the anchor layer, and a coating film is formed. A multilayer release film is produced by uniformly heating and drying to form surface layer 1 or surface layer 2.
Moreover, in the said hot press molding, a multilayer release film is manufactured by superposing | stacking the film used as the surface layer 1, the film used as an intermediate | middle layer, and the film used as the surface layer 2, for example.

The multilayer release film of the present invention is preferably subjected to a release treatment on the surface for the purpose of improving the release property.
The release treatment method is not particularly limited. For example, a known method such as a method of applying or spraying a release agent such as silicone or fluorine on the surface of a multilayer release film, a method of performing heat treatment, friction treatment, or the like. This method can be used. These mold release processes may be used independently and may use 2 or more types together.

The method of the heat treatment is not particularly limited, and examples thereof include a method of passing between rolls heated to a constant treatment temperature and a method of putting in a heating oven. The temperature of the heat treatment is not particularly limited as long as it is not lower than the glass transition temperature and not higher than the melting point of the resin constituting the surface layer 1, the surface layer 2, and the intermediate layer, but the preferable lower limit is 120 ° C and the preferable upper limit is 200 ° C. . If the heat treatment temperature is less than 120 ° C., the effect of improving the releasability by the heat treatment may be hardly obtained. When the heat treatment temperature exceeds 200 ° C., the surface layer 1, the surface layer 2, or the intermediate layer is likely to be deformed during heat treatment and may not be manufactured. A more preferable lower limit of the heat treatment temperature is 170 ° C., and a more preferable upper limit is 190 ° C.

The method of the said friction process is not specifically limited, For example, the method of rubbing the said surface layer 1 or the said surface layer 2 using cloths, such as rotating materials, such as a metal roll, a brush, and a gauze, is mentioned. Although the speed at the time of the friction is not particularly limited, a preferable lower limit of the speed with respect to the surface layer 1 or the surface layer 2 is 30 m / min.

The use of the multilayer release film of the present invention is not particularly limited. For example, in the production of a printed circuit board such as a flexible printed circuit board, a coverlay film or a reinforcing plate is heated via a thermosetting adhesive or a thermosetting adhesive sheet. It can be suitably used when adhering to a printed circuit board by press molding. The multilayer release film of the present invention has a surface layer 1 having a thickness of 5 μm or more and less than 25 μm and a surface layer 2 having a thickness of 25 μm or more and less than 50 μm via an intermediate layer. By performing hot press molding so that the surface layer 2 is on the hot press plate side, the generation of wrinkles is suppressed and the flow of the adhesive from the coverlay film or the like is suppressed. Yield in molding can be improved.
In the method for producing a printed board using the multilayer release film of the present invention, in hot press molding, a surface layer (surface layer 1) having a thickness of 5 μm or more and less than 25 μm has a thickness on the circuit surface side of the printed board body. A method for producing a printed circuit board in which a multilayer release film is disposed so that a surface layer (surface layer 2) having a thickness of 25 μm or more and less than 50 μm is on the hot press plate side is also one aspect of the present invention.

ADVANTAGE OF THE INVENTION According to this invention, it is excellent in wrinkle resistance and can provide the multilayer release film which can suppress the outflow of the adhesive agent from a coverlay film etc. Moreover, according to this invention, the manufacturing method of the printed circuit board using this multilayer release film can be provided.

FIG. 1 shows the results of comprehensive evaluation of the multilayer release films obtained in Examples 1 to 9 and Comparative Examples 1 to 27, the horizontal axis indicates the thickness of the surface layer 1 of the multilayer release film, and the vertical axis indicates the multilayer release. It is the figure shown on the graph made into the thickness of the surface layer 2 of a film.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.

(Examples 1-9, Comparative Examples 1-27)
In a molding apparatus consisting of a three-layer coextrusion mold and three extruders, a crystalline aromatic polyester resin (polybutylene terephthalate, manufactured by Mitsubishi Engineering Plastics, Novade Juran 5010R5) and a polyolefin resin (manufactured by Nippon Polyethylene) , LDPE, trade name “NOVATEC”) by using a extruder (GM30-28, GM30-28 (screw diameter 30 mm, L / D28)) and co-extrusion with a T die width of 400 mm. A milky white three-layer resin film having a structure in which the front and back surfaces of a polyolefin-based resin layer (intermediate layer) having a thickness of 70 μm were sandwiched between two polyester resins (surface layer 1 and surface layer 2) each having a thickness shown in Table 1 was obtained.

Next, the pattern processed on the surface of the cooling roll is transferred to the surface of the obtained three-layer resin film to form irregularities on the surface of the three-layer resin film, and RSm = 50 μm of surface layer 1 and surface layer 2 A three-layer release film with RSm = 200 μm was obtained.

<Evaluation 1>
The following evaluation was performed about the multilayer release film obtained in Examples 1-9 and Comparative Examples 1-27. The results are shown in Table 1.

(1) Wrinkle performance evaluation CCL (20 cm × 20 cm, polyimide thickness 25 μm, copper foil 35 μm), coverlay (20 cm × 20 cm, polyimide thickness 15 μm, epoxy resin adhesive layer 25 μm), and obtained multilayer release film Are stacked in this order from the bottom, placed between press dies heated at 180 ° C. in advance using a slide-type vacuum heater press (MKP-3000V-WH-ST, manufactured by Mikado Technos), and then aligned. (Approximately 10 seconds from the installation until the actual pressure is applied), and press for 2 minutes at 50 kg / cm ² under vacuum conditions, and a flexible printed circuit board (FPC) evaluation sample consisting of CCL and coverlay Produced.

Thereafter, the FPC evaluation sample and the multilayer release film were taken out, peeled off the multilayer release film, and then the number of wrinkles transferred onto the coverlay surface was measured. When the number of wrinkles transferred on the coverlay surface was 0, “◯”, when it was 1-9, “△”, and when it was 10 or more, “x” evaluated.
In addition, when the number of wrinkles is 30 or less, it can be said that it has sufficient wrinkle resistance as a release film at the time of manufacturing a printed circuit board. More preferably, the number of wrinkles is 5 or less. On the other hand, when the number of wrinkles exceeds 30, the wrinkle resistance is insufficient as a release film for producing a printed circuit board.

(2) Adhesive flow rate evaluation CCL (20 cm × 20 cm, polyimide thickness 25 μm, copper foil 35 μm), coverlay (20 cm × 20 cm, polyimide thickness 25 μm, epoxy resin adhesive layer 35 μm), and the obtained multilayer separation After stacking the mold films in this order from the bottom, the slide film was placed between press dies preheated at 180 ° C. using a slide-type vacuum heater press (MKP-3000V-WH-ST, manufactured by Mikado Technos) and aligned. Then, pressing was started (about 10 seconds from when the pressure was actually applied to setting), and pressing was performed at 50 kg / cm ² for 2 minutes to prepare an FPC evaluation sample composed of CCL and a coverlay. In addition, the hole ((PHI) 1mm) for adhesive flow out amount evaluation was produced previously in the coverlay.

Thereafter, the FPC evaluation sample and the multilayer release film were taken out, and the length of the adhesive that flowed out was measured by observing the hole for evaluating the adhesive flow-out amount on the coverlay with a microscope. The case where the length of the flowed-out adhesive was less than 100 μm was evaluated as “◯”, the case where it was 100 μm or more and less than 120 μm, “Δ”, and the case where it was 120 μm or more was evaluated as “x”.

(3) Comprehensive evaluation In (1) Wrinkle performance evaluation and (2) Adhesive flow-out amount evaluation described above, when both evaluations are “◯”, “○” indicates that either evaluation is “○”. And when the other evaluation is “△”, at least one evaluation is “×”, or when both evaluations are “△” ".
The results of the comprehensive evaluation are shown on a graph in which the horizontal axis is the thickness of the surface layer 1 of the multilayer release film and the vertical axis is the thickness of the surface layer 2 of the multilayer release film (FIG. 1).

(Examples 10 to 11)
Three-layer mold release having an average length RSm of roughness curve elements shown in Table 2 in the same manner as in Example 9 except that the cooling roll used when forming irregularities on the surface of the three-layer resin film was changed. A film was prepared.

<Evaluation 2>
The following evaluation was performed on the multilayer release films obtained in Examples 9, 10 and 11. The results are shown in Table 2.

(1) Wrinkle performance evaluation In the above <Evaluation 1> except that it was pressed at 50 kg / cm ² for 2 minutes under vacuum conditions, except that it was pressed at 50 kg / cm ² for 2 minutes under normal pressure conditions (1 ) An FPC evaluation sample composed of CCL and coverlay was prepared in the same manner as the wrinkle performance evaluation.
In addition, it is easy to produce the wrinkle to a multilayer release film to press on normal pressure conditions rather than pressing on vacuum conditions.

Thereafter, the FPC evaluation sample and the multilayer release film were taken out, peeled off the multilayer release film, and then the number of wrinkles transferred onto the coverlay surface was measured. When the number of wrinkles transferred on the coverlay surface is 0, “「 ”, when it is 1-5,“ ◯ ”, when it is 6-10,“ △ ”. The case of 11 or more was evaluated as “x”.

(2) Adhesive flow-out amount evaluation The adhesive flow-out amount was evaluated in the same manner as (2) Adhesive flow-out amount evaluation in <Evaluation 2> described above.

ADVANTAGE OF THE INVENTION According to this invention, it is excellent in wrinkle resistance and can provide the multilayer release film which can suppress the outflow of the adhesive agent from a coverlay film etc. Moreover, according to this invention, the manufacturing method of the printed circuit board using this multilayer release film can be provided.

Claims (3)

A multilayer release film having an intermediate layer and two surface layers laminated on both sides of the intermediate layer,
One of the two surface layers has a thickness of 5 μm or more and less than 25 μm, and the other has a thickness of 25 μm or more and less than 50 μm. A surface layer having a thickness of 5 μm or more and less than 25 μm is a method according to JIS B0601: 2001, using a stylus having a tip radius of 2 μm and a conical taper angle of 60 °, a measuring force of 0.75 mN, and a cutoff value λs = 2. The multilayer release film according to claim 1, wherein the average length RSm of the roughness curve element measured under the conditions of 0.5 µm and λc = 0.8 mm is 300 µm or less. A method for producing a printed circuit board using the multilayer release film according to claim 1,
In hot press molding, a multilayer release film is placed so that the surface layer with a thickness of 5 μm or more and less than 25 μm is on the circuit surface side of the printed circuit board body, and the surface layer with a thickness of 25 μm or more and less than 50 μm is on the heat press plate side. A printed circuit board manufacturing method comprising:

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