JP2011175988A - Mold releasing film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mold releasing film applicable to various kinds of thermoplastic liquid crystal polymer films. <P>SOLUTION: The mold releasing film includes an ultrahigh molecular weight polyolefin film layer and a reinforcing layer which are laminated. In the ultrahigh molecular weight polyolefin film layer, the degree of a molecular orientation SOR in the length direction of the film is in a range of 0.95 or higher and lower than 1.05, and the average of the coefficient of thermal expansion in the plane direction of the film is a negative value. In the reinforcing layer, the average of the coefficient of thermal expansion in the plane direction of the reinforcing layer is a positive value. Such a mold releasing film is used for hot press molding in the process of manufacturing a printed wiring board using a film comprising a thermoplastic liquid crystal polymer as (i) a base material, (ii) a cover-lay film or (iii) both the base material and the cover-lay film. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a release film that is excellent in heat resistance, releasability, and non-contamination, and that can be easily disposed of, and is used during hot press molding of a printed wiring board, and a printed wiring board using the release film. It relates to a manufacturing method.

  Conventionally, in a manufacturing process of a printed wiring board such as a printed wiring board, a flexible wiring board, or a multilayer printed wiring board, a film (hereinafter referred to as a TLCP film) made of a thermoplastic liquid crystal polymer that forms an optically anisotropic molten phase. In copper-clad laminates with abbreviated), release films are used when hot pressing copper foil.

  In addition, when a cover lay film made of a TLCP film is thermally bonded with a thermosetting adhesive by a hot press to a flexible printed wiring board body on which an electric circuit is formed in the manufacturing process of the flexible printed wiring board, In order to prevent the lay film and the hot press plate from adhering to each other, a release film is widely used.

These release films are required to have heat resistance so as to be used at a high temperature by hot press molding when the TLCP film is melted by heat.
For example, Patent Document 1 discloses a release film that is excellent in heat resistance, release properties, and non-contamination properties and can be easily disposed of. In this document, a combination of a metal layer and a thermoplastic film having a specific shear modulus is described as a release film. And in such a release film, since this thermoplastic film has a specific shear modulus, it is possible to prevent a decrease in cushioning property due to thermal deformation of the thermoplastic film during hot press molding. It is also described that it exhibits excellent followability with respect to irregularities.

  However, when this release film is used, depending on the type of TLCP film, the TLCP film may be deformed and cannot be used as a printed wiring board.

International Publication No. 2008/012940 Pamphlet

  An object of the present invention is to provide a release film that can be applied to a wide variety of TLCP films even when the TLCP film is used as a substrate or coverlay film of a printed wiring board.

  Another object of the present invention is to provide a release film capable of preventing the circuit deformation occurring in a printed wiring board to a very high level without adjusting the thermal expansion coefficient of the TLCP film in advance.

  Yet another object of the present invention is to use such a release film to extremely highly prevent circuit deformation even when a printed wiring board using a TLCP film is hot press molded at a high temperature. Another object of the present invention is to provide a method for manufacturing a printed wiring board.

  The present inventors examined a release film in view of the existence of a TLCP film that is deformed during hot pressing and cannot be used as a printed wiring board. First, when performing hot pressing, the TLCP film has a positive coefficient of thermal expansion, so it has traditionally been thought that the thermoplastic film forming the release film must also have a positive coefficient of thermal expansion in order to follow it. It was.

  However, when reconsidering this point, in the case of a release film composed of a plurality of layers, when a thermoplastic film having a positive thermal expansion coefficient and a metal layer having a positive thermal expansion coefficient are combined, TLCP It has been found that the coefficient of thermal expansion exceeds the thermal expansion coefficient of the film, and depending on the type of the TLCP film, stress derived from the thermal expansion of the thermoplastic film is applied to the TLCP film, and as a result, the TLCP film is deformed.

  And then, when an effective means for preventing such deformation of the TLCP film was examined, an ultrahigh molecular weight polyolefin film having a negative thermal expansion coefficient and a reinforcing layer having a positive thermal expansion coefficient were combined. By this, not only in the mold release property and the cushioning property in the thickness direction, but also in the temperature range for hot pressing, it is possible to effectively prevent applying stress due to thermal expansion to the TLCP film. The present invention has been completed by finding that it is a release film applicable to a wide variety of TLCP films.

That is, the present invention relates to a film made of a thermoplastic liquid crystal polymer that forms an optically anisotropic melt phase. (I) a substrate, (ii) a coverlay film, or (iii) a substrate and a coverlay film In the manufacturing process of the printed wiring board used as both, it is a release film used when performing hot press molding,
The release film comprises an ultra-high molecular weight polyolefin film layer and a reinforcing layer superimposed,
The ultrahigh molecular weight polyolefin film layer has a molecular orientation degree SOR in the longitudinal direction of the film in the range of 0.95 or more and less than 1.05, and the average of the thermal expansion coefficient in the plane direction of the film is a negative value,
The reinforcing layer is a release film whose average thermal expansion coefficient in the plane direction of the reinforcing layer is a positive value.

The ultrahigh molecular weight polyolefin film layer may have an average thermal expansion coefficient (M _UP ) in the plane direction of −1 × 10 ⁻⁶ cm / cm / ° C. or less, and the reinforcing layer has a thermal expansion coefficient in the plane direction. The average coefficient (M _RE ) may be in the range of 1 × 10 ⁻⁶ to 30 × 10 ⁻⁶ cm / cm / ° C.

  The ultrahigh molecular weight polyolefin constituting the ultrahigh molecular weight polyolefin film layer usually has a viscosity average molecular weight of 1 million or more in many cases.

Further, the release film, the average of the average of the planar direction of the thermal expansion coefficient of the ultra-high molecular weight polyolefin film layer (M _UP), the average of the planar direction of the thermal expansion coefficient of the reinforcing layer (M _RE) (M _T) However, it may be a negative value.

  The thickness of each layer can be appropriately set. For example, the thickness (A) of the ultrahigh molecular weight polyolefin film layer may be about 30 to 200 μm, and the thickness (B) of the reinforcing layer is The ratio (B) / (A) of the thickness (B) of the reinforcing layer to the thickness (A) of the ultra-high molecular weight polyolefin film layer may be 60 / 40-30. It may be about / 70.

The present invention further provides a film comprising a thermoplastic liquid crystal polymer that forms an optically anisotropic melt phase, wherein (i) a substrate, (ii) a coverlay film, or (iii) a substrate and a coverlay film. Using both as a method of manufacturing a printed wiring board by hot press molding,
A method for producing a printed wiring board in which the release film according to any one of claims 1 to 7 is disposed in such a manner that the reinforcing layer is in contact with the press hot plate at the time of hot press molding is also included.

  For example, the hot press molding temperature may be selected from a range (for example, about 250 to 320 ° C.) that is at least 15 ° C. lower than the melting point of the thermoplastic liquid crystal polymer and at most 15 ° C. higher than the melting point.

The present invention also includes a printed wiring board manufactured by such a manufacturing method. The present invention also includes a printed wiring board, a cover lay film, or a film made of a thermoplastic liquid crystal polymer that forms an optically anisotropic molten phase for forming both a substrate and a cover lay film;
Placed above and below the wiring board or the coverlay film so as to sandwich the printed wiring board or the coverlay film, in combination with a reinforcing layer whose average thermal expansion coefficient in the plane direction of the reinforcing layer is a positive value An ultra-high molecular weight polyolefin film for constituting a release film;
In addition, the invention relates to a material for laminating that is sandwiched between press hot plates and is subjected to hot press molding. In this laminating material, the ultrahigh molecular weight polyolefin film layer has a molecular orientation in the longitudinal direction of the film. The degree SOR is in the range of 0.95 or more and less than 1.05, and the average thermal expansion coefficient in the plane direction of the film is a negative value.

  In the present specification, the average of the thermal expansion coefficients in the plane direction means the thermal expansion coefficient in the machine axis direction (hereinafter abbreviated as MD direction) in the plane direction of the film and the like and the direction orthogonal to the machine axis direction (hereinafter referred to as “the direction of the machine axis”). , Which is abbreviated as TD direction) and means an average value obtained by dividing the sum of the thermal expansion coefficients by 2.

  According to the present invention, a release film is formed by combining an ultra-high molecular weight polyolefin film layer having a negative coefficient of thermal expansion and a reinforcing layer having a positive coefficient of thermal expansion. Therefore, for a wide variety of TLCP films, Even if applied, deformation due to hot press molding of the printed wiring board can be reduced.

  Furthermore, by adjusting the thermal expansion coefficient of the ultrahigh molecular weight polyolefin film layer and the reinforcing layer to a specific value, the circuit deformation that occurs in the printed wiring board can be extremely advanced without adjusting the thermal expansion coefficient of the TLCP film in advance. Can be prevented.

[Release film]
The release film of the present invention comprises a TLCP film (that is, a film made of a thermoplastic liquid crystal polymer that forms an optically anisotropic melt phase), (i) a substrate, (ii) a coverlay film, or (iii) ) Used in hot press molding in the manufacturing process of printed wiring boards used as both a base material and a coverlay film. The release film is a laminate of an ultrahigh molecular weight polyolefin film and at least one reinforcing layer. Prepare in the state.

(Ultra-high molecular weight polyolefin film)
In the ultrahigh molecular weight polyolefin film, the molecular orientation degree SOR in the longitudinal direction of the film is in the range of 0.95 or more and less than 1.05, and the average thermal expansion coefficient in the plane direction of the film is a negative value.

  When the molecular orientation degree SOR in the longitudinal direction of the ultrahigh molecular weight polyolefin film is in the range of 0.95 or more and less than 1.05, the orientation state of the molecules can be kept isotropic, During subsequent cooling, it is possible to prevent the printed wiring board from being unevenly distorted or deformed due to the anisotropy of the film. In the case of a high-density wiring or a thin wiring board, the SOR is more preferably in the range of 0.98 to 1.03.

Also, in order to prevent the deformation of the circuit of the printed wiring board and the distortion of the entire wiring board, the average (M _UP ) of the thermal expansion coefficient in the plane direction of the ultrahigh molecular weight polyolefin film needs to be a negative value. It is preferably −1 × 10 ⁻⁶ cm / cm / ° C. or less, more preferably about −500 × 10 ⁻⁶ to −10 × 10 ⁻⁶ cm / cm / ° C., and further preferably −400. It may be about × 10 ⁻⁶ to −30 × 10 ⁻⁶ cm / cm / ° C.

Since the thermal expansion coefficient of the printed wiring board is a positive value (for example, about 18 × 10 ⁻⁶ cm / cm / ° C.), the printed wiring board is easily deformed to the thermal expansion side due to stress in the plane direction during hot pressing. Therefore, the thermal expansion coefficient of the ultra-high-molecular-weight polyolefin film constituting the release film is set to a negative value, and the force that deforms to the heat shrink side due to the stress in the plane direction is exerted, so that the heat of the entire laminate that works during hot pressing is applied. Expansion can be reduced.

  The thickness of the ultrahigh molecular weight polyolefin film is preferably in the range of about 30 to 200 μm, and more preferably in the range of about 30 to 100 μm. When the film is too thick, the thermal contraction force due to the negative thermal expansion coefficient of the film increases, and the printed wiring board may be distorted in the contraction direction. In addition, if the film is too thin, it will be close to the thickness of the circuit provided on the printed wiring board, and the cushioning property that the release film should have and the fluidity will be insufficient. Adhesion may be reduced.

  The method for producing the ultrahigh molecular weight polyolefin film is not particularly limited as long as it has a predetermined SOR and thermal expansion coefficient, and may be produced by various methods. For example, such an ultra high molecular weight polyolefin film can be obtained by inflation molding an ultra high molecular weight polyolefin having a predetermined intrinsic viscosity.

  For inflation molding, an ultrahigh molecular weight polyolefin having an intrinsic viscosity [η] measured at 135 ° C. in a decalin solvent of 5 dl / g or more, preferably 7 dl / g or more, more preferably 8 to 25 dl / g is preferably used. .

  When the intrinsic viscosity is less than 5 dl / g, mechanical strength such as tensile strength and impact strength is not sufficient. In addition, since the melt viscosity is low, twisting due to co-rotation of the melt of the ultra-high molecular weight polyolefin and the mandrel in the screw die and uneven thickness due to bending of the mandrel are likely to occur, and it is difficult to obtain a uniform film, resulting in poor moldability. The upper limit of the intrinsic viscosity [η] is not particularly limited, but those exceeding 25 dl / g tend to be inferior in extrusion moldability because the melt viscosity is too high.

  The viscosity average molecular weight of the ultrahigh molecular weight polyolefin may be, for example, 1 million or more, preferably about 2 million to 7 million, and more preferably about 3 million to 6 million. In addition, the measuring method of the intrinsic viscosity number used for calculation of a viscosity average molecular weight can be measured based on JISK7367-3: 1999.

Further, the shear modulus at the press molding temperature of the ultrahigh molecular weight polyolefin can be selected from a wide range of 5 × 10 ⁴ to 1 × 10 ⁷ Pa, preferably about 1 × 10 ^{5 to} 5 × 10 ⁶ Pa. More preferably, it is about 1 × 10 ^{5 to} 5 × 10 ⁵ Pa (for example, 1 × 10 ⁵ or more and less than 5 × 10 ⁵ Pa), and particularly preferably about 1 × 10 ^{5 to} 3 × 10 ⁵ Pa. May be. The shear modulus is obtained by dynamic viscoelasticity measurement and can be measured with a viscoelastic rheometer.

  Examples of the ultra high molecular weight polyolefin include ultra high molecular weight polyethylene and ultra high molecular weight polypropylene. Among these, ultra high molecular weight polyethylene is preferably used. The ultrahigh molecular weight polyethylene contains ethylene as a repeating unit, and may further contain other copolymerization components in addition to ethylene. Examples of other copolymer components include C2-C20 α-olefins such as propylene, 1-butene, 1-hexene, 1-octene and 4-methyl-1-pentene; methyl acrylate, ethyl acrylate, Α, β-unsaturated carboxylic acid esters such as butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate; acrylonitrile, methacrylate Examples include ronitrile, acrolein, methacrolein, ethyl vinyl ether, styrene, vinyl acetate and the like. These copolymerization components can be used alone or in combination of two or more. Of these copolymer components, α-olefins are preferred. The ultra high molecular weight polyethylene preferably contains 99.5 mol% or more, preferably 99.8 mol% or more of the repeating units.

  Further, the ultrahigh molecular weight polyolefin may be blended with an inorganic filler, fiber, nucleating agent, mold release agent, antioxidant (anti-aging agent), heat stabilizer and the like, if necessary. These may be used alone or in combination of two or more.

  The inorganic filler is not particularly limited, and examples thereof include layered double hydrates such as calcium carbonate, titanium oxide, mica, talc, barium sulfate, alumina, silicon oxide, and hydrotalcite.

  The fibers are not particularly limited, and examples thereof include inorganic fibers such as glass fibers, carbon fibers, boron fibers, silicon carbide fibers, and alumina fibers; organic fibers such as aramid fibers.

  The antioxidant 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-t-butyl-4-hydroxy-5-methylphenyl) -propionyloxy] -1,1-dimethylethyl} -2,4,8,10-tetraoxaspiro [5 , 5] hindered phenolic antioxidants such as undecane.

  The heat stabilizer is not particularly limited, and examples thereof include 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, pentaerythryltetrakis (3-laurylthiopro) Pionate), ditridecyl 3,3'-thiodipropionate and the like.

  Using such ultrahigh molecular weight polyolefin, inflation molding can be performed by a known or conventional method to obtain an ultrahigh molecular weight polyolefin film having a predetermined SOR and thermal expansion coefficient used in the present invention. As long as the obtained film exhibits a predetermined SOR and thermal expansion coefficient, three-dimensional crosslinking may be introduced. The degree of polymerization of the polymer is increased during polymerization, or post-treatment such as electron beam crosslinking after polymerization. May be performed. Furthermore, the ultrahigh molecular weight polyolefin film may be used in a single layer, but may have a multilayer structure, and a film made of different materials may be multilayered as necessary.

(Reinforcing layer)
The reinforcing layer needs to have a positive average thermal expansion coefficient in the plane direction of the reinforcing layer, for example, within a range of 1 × 10 ⁻⁶ to 30 × 10 ⁻⁶ cm / cm / ° C. Is preferred.
If the thermal expansion coefficient is a negative value, the degree of thermal shrinkage increases due to the sum of the negative thermal expansion coefficient of the ultrahigh molecular weight polyolefin film and the printed wiring board is distorted in the shrinking direction. On the other hand, if the thermal expansion coefficient is too high, the printed wiring board may be distorted in the expansion direction.

  The reinforcing layer preferably has heat resistance. When a cover lay film made of a liquid crystal polymer is bonded to a printed wiring board by heat melting, a high lamination temperature is required and is usually 260 ° C. or higher. Therefore, as a material suitable for the reinforcing plate, a metal foil with little oxidation deterioration, for example, an aluminum foil or a stainless steel foil is used. As the other material, a polyimide film which is a thermosetting resin is suitable. These materials may be used alone or in combination of two or more. Furthermore, the reinforcing layer may be used as a single layer, but may have a multilayer structure, and a film made of different materials may be multilayered as necessary.

  The thickness of the reinforcing layer is preferably in the range of about 10 to 100 μm, and more preferably in the range of about 20 to 50 μm. If the reinforcing layer is too thick, the contribution of the positive thermal expansion coefficient in the plane direction will increase, offsetting the negative thermal expansion coefficient contribution of the ultra-high molecular weight polyolefin film, and distorting the printed wiring board. End up. On the other hand, if the reinforcing layer is too thin, the contribution of the negative thermal expansion coefficient of the ultra-high molecular weight polyolefin film increases, and the printed wiring board is distorted.

  In the release film of the present invention, the ultrahigh molecular weight polyolefin film and the reinforcing layer are laminated in a laminated state. The superposition may be integrated as well as simple superposition. The ultrahigh molecular weight polyolefin film and the reinforcing layer are usually composed of one sheet each, but a plurality of layers may be used.

For example, in the release film, when considering the thermal expansion coefficient of the entire release film, the average (M _UP ) of the thermal expansion coefficient in the planar direction of the ultrahigh molecular weight polyolefin film layer and the thermal expansion coefficient in the planar direction of the reinforcing layer The average (M _T ) with the average (M _RE ) may be a negative value, preferably about −1 × 10 ⁻⁶ to −200 × 10 ⁻⁶ cm / cm / ° C. More preferably, it may be about −5 × 10 ⁻⁶ to −150 × 10 ⁻⁶ cm / cm / ° C.

  In the release film, the ratio (B) / (A) of the thickness (B) of the reinforcing layer to the thickness (A) of the ultrahigh molecular weight polyolefin film layer depends on the thermal expansion coefficient forming each layer. However, from the viewpoint of realizing releasability and adhesion while offsetting the sign of each thermal expansion coefficient, for example, (B) / (A) is 60 / 40-30 / It may be about 70, preferably about 55/45 to 40/60.

  The surface of the ultrahigh molecular weight polyolefin film used for the release film of the present invention preferably has smoothness, but may have slipping properties, antiblocking properties and the like necessary for handling. In addition, an appropriate embossed pattern may be provided on at least one surface for the purpose of removing air during hot press molding.

  Further, a release agent such as a silicone release agent may be applied to the surface on the side of the reinforcing layer opposite to the ultrahigh molecular weight polyolefin film layer to enhance the release property.

[Method of manufacturing printed wiring board]
In the method for producing a printed wiring board of the present invention, a TLCP film is used as (i) a base material, (ii) a coverlay film, or (iii) both a base material and a coverlay film, and printed wiring is formed by hot press molding. When producing a plate, the release film is arranged so that the reinforcing layer is in contact with the hot press plate.

(TLCP film)
In the present invention, the raw material of the thermoplastic liquid crystal polymer film used as the substrate of the printed wiring board or as the coverlay film is not particularly limited, but specific examples thereof include (1) to Examples thereof include known thermotropic liquid crystal polyesters and thermotropic liquid crystal polyester amides derived from the compounds classified as (4) and derivatives thereof. However, in order to obtain a polymer capable of forming an optically anisotropic melt phase, it goes without saying that there is an appropriate range for each combination of raw material compounds.

(1) Aromatic or aliphatic dihydroxy compounds (see Table 1 for typical examples)

(2) Aromatic or aliphatic dicarboxylic acids (see Table 2 for typical examples)

(3) Aromatic or aliphatic hydroxycarboxylic acids (see Table 3 for typical examples)

(4) Aromatic diamine, aromatic hydroxyamine or aromatic aminocarboxylic acid (see Table 4 for typical examples)

  Typical examples of the liquid crystal polymer obtained from these raw material compounds include copolymers having the structural units shown in Table 5.

  The thermoplastic liquid crystal polymer used in the present invention is within the range of about 200 to about 400 ° C., particularly within the range of about 250 to about 350 ° C. for the purpose of obtaining the desired heat resistance and workability of the film. However, those having a relatively low melting point are easier to produce from the viewpoint of film production.

  In the present invention, the liquid crystal polymer film is obtained by extruding a thermoplastic liquid crystal polymer. Any extrusion method can be used for this purpose, but the well-known T-die film-drawing method, inflation method and the like are industrially advantageous. Moreover, the film obtained by extending | stretching the laminated body of the formed film and a support film can also be used. In particular, in the laminate stretching method and the inflation method, stress is applied not only in the mechanical axis direction of the film (hereinafter abbreviated as MD direction) but also in the direction orthogonal thereto (hereinafter abbreviated as TD direction). And a film having a balance of mechanical properties and thermal properties in the TD direction can be obtained.

When the release film of the present invention is used, various TLCP films can be used as a substrate or a coverlay film regardless of the change in the thermal expansion coefficient of the TLCP film. That is, the thermal expansion coefficient of the TLCP film may be substantially constant or changed before and after hot press molding. In particular, when the release film of the present invention is used, the thermal expansion coefficient of the TLCP film varies greatly before and after hot press molding (for example, the thermal expansion coefficient (H _a ) after hot press molding and hot press molding. Even if the difference from the previous coefficient of thermal expansion (H _b ) is about 10-50 × 10 ⁻⁶ cm / cm / ° C., preferably about 20-40 × 10 ⁻⁶ cm / cm / ° C., Deformation can be prevented.

  The thermoplastic liquid crystal polymer film used in the present invention may have an arbitrary thickness, and includes a plate or sheet having a thickness of 2 mm or less. However, when a copper-clad laminate using a thermoplastic liquid crystal polymer film as an electrical insulating layer is used as a printed wiring board, the film thickness is preferably in the range of 20 to 150 μm. More preferably within the range of 50 μm.

  If the film thickness is too thin, the rigidity and strength of the film will be reduced, so when mounting electronic parts on the resulting printed wiring board, it will be deformed by pressure, resulting in poor wiring position accuracy. Cause.

  Moreover, as an electrical insulation layer of a main wiring board such as a personal computer, a composite body of the thermoplastic liquid crystal polymer film and another electrical insulation material such as a glass cloth base material can be used. The thermoplastic liquid crystal polymer film may contain additives such as a lubricant and an antioxidant.

  For example, the printed wiring board can be manufactured by using the TLCP film as a base material and forming a circuit layer formed of a conductor such as copper on the TLCP film by a known or conventional method. Examples of such printed wiring boards include flexible printed wiring boards and multilayer printed wiring boards.

  Moreover, when using a TLCP film as a coverlay film, a coverlay film and a printed wiring board can be adhere | attached by hot press molding. In this case, if necessary, a thermosetting resin such as an epoxy resin may be applied between the coverlay film and the printed wiring board, and then hot press molding may be performed.

  In the present invention, as the press molding temperature, an appropriate temperature is selected depending on the kind of the thermoplastic liquid crystal polymer constituting the TLCP film. For example, the molding temperature is 15 ° C. lower than the melting point of the thermoplastic liquid crystal polymer, And it may be performed at a temperature selected from a range of 15 ° C. higher than the melting point or less. For example, such a molding temperature may be selected within a range of about 250 to 320 ° C (preferably about 260 to 310 ° C).

  And in hot press molding, for example, the reinforcing layer side constituting the release film of the present invention is applied to the press hot plate, and the ultrahigh molecular weight polyolefin film layer side is applied to the circuit surface or coverlay film surface of the printed wiring board. Can be used by guessing.

[Printed wiring board]
The printed wiring board obtained using the release film of the present invention can extremely highly prevent circuit deformation due to hot press molding, and has a high density wiring or a thin wiring board. However, it can be used effectively without being affected by distortion due to circuit deformation.
For example, the circuit board deformation ratio obtained by measuring the distance between circuits on the wiring board before and after hot pressing may be about 0.01 to 0.06%, and preferably 0.05% or less. .

[Lamination materials]
Furthermore, in this invention, it can also distribute | circulate as a lamination | stacking material comprised by the said TLCP film and the said ultra high molecular weight polyolefin film. In this case, the TLCP film is used to form a printed wiring board, a coverlay film, or both a substrate and a coverlay film, and the ultrahigh molecular weight polyolefin film sandwiches the printed wiring board or the coverlay film. Thus, it is used in combination with a reinforcing layer placed above and below the wiring board or the coverlay film.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited at all by this Example. In addition, the various physical properties in an Example are calculated | required with the following method.

(Molecular orientation SOR)
The molecular orientation degree SOR (Segment Orientation Ratio) is an index that gives the degree of molecular orientation, and is different from the conventional MOR (Molecular Orientation Ratio), and takes into account the thickness of the object. This molecular orientation degree SOR is calculated as follows.

First, in a well-known microwave molecular orientation measuring instrument, a liquid crystal polymer film is inserted into a microwave resonant waveguide so that the film surface is perpendicular to the traveling direction of the microwave, and the microscopic film transmitted through the film is transmitted. The electric field strength of the wave (microwave transmission strength) is measured.
And based on this measured value, m value (it calls a refractive index) is computed by following Formula.
m = (Zo / Δz) X [1-νmax / νo]
Where Zo is a device constant, Δz is the average thickness of the object, νmax is the frequency that gives the maximum microwave transmission intensity when the microwave frequency is changed, and νo is the average thickness of zero (that is, the object is Is the frequency that gives the maximum microwave transmission intensity.

Next, when the rotation angle of the object with respect to the vibration direction of the microwave is 0 °, that is, the vibration direction of the microwave and the direction in which the molecules of the object are best oriented, the minimum microwave transmission intensity is given. The degree of molecular orientation SOR is calculated by m ₀ / m _90, where m ₀ when the direction coincides with m ₀ and m ₉₀ when the rotation angle is 90 ° is m ₉₀ .

(Coefficient of thermal expansion cm / cm / ° C)
The thermal expansion coefficient α is a coefficient obtained by dividing the expansion coefficient when heated at a constant heating rate from room temperature to near the heat distortion temperature of the film by the temperature difference, and is calculated as follows.

First, using a known thermomechanical analyzer, one end of a strip cut film is fixed, a tensile load is applied to the other end, and the amount of expansion when heated at a constant temperature increase rate is measured. Thermal expansion, assuming that the length L ₀ (mm) of the film in the load direction of the film is L ₁ (mm), the temperature is T ₂ (° C.), and the room temperature is T ₁ (° C.). The coefficient α can be calculated by the following formula.
α = [(L ₁ −L ₀ ) / (T ₂ −T ₁ ) / L ₀ (× 10 ⁻⁶ cm / cm / ° C.)
In the present invention, L ₀ = 20 mm, T ₂ = 150 ° C., T ₁ = 25 ° C., and the tensile load is 1 g.

(Shear modulus Pa)
Using a viscoelastic rheometer (TA Instrument Japan, AR2000), the temperature was increased at a rate of 4 ° C./min, the frequency was 1 Hz, the strain was 0.1%, and the normal stress was 5N.

(Releasability)
The ease of peeling of the release film from the laminated printed wiring board was evaluated according to the following criteria.
Good: The release film could be easily peeled off from the printed wiring board after hot press molding, and no deformation was found on the printed wiring board after peeling.
Defect: It was difficult to peel off the release film from the printed wiring board after hot press molding, and the printed wiring board after the peeling was deformed.

(Circuit dimension change rate%)
The distance between the circuits on the wiring board before and after hot pressing was measured and calculated as a percentage of the value obtained by dividing the change in distance before and after hot pressing by the distance after hot pressing.

(Melting point of TLCP film ° C)
The film was obtained by observing the thermal behavior of the film using a differential scanning calorimeter. That is, after the TLCP film was heated at a rate of 10 ° C./min to be completely melted, the melt was rapidly cooled to 50 ° C. at a rate of 10 ° C./min, and then heated again at a rate of 10 ° C./min. The position of the endothermic peak that occasionally appears was recorded as the melting point.

Example 1
As the ultrahigh molecular weight polyolefin film layer, the degree of molecular orientation SOR is 1.01, the average thermal expansion coefficient is −221.5 × 10 ⁻⁶ cm / cm / ° C., and the shear elastic modulus at the hot press lamination temperature is 1.5. * 10 ⁵ Pa ultra high molecular weight polyethylene sheet (manufactured by Sakushin Kogyo Co., Ltd., “Saxin New Light Film Innovate”, thickness 50 μm) and a reinforcing layer having an average thermal expansion coefficient of 23 × 10 ⁻⁶ cm A release film was constructed by superposing aluminum foil (manufactured by Toyo Aluminum Co., Ltd., single gloss type, thickness 50 μm) at / cm / ° C.

  A copolymer of p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid (molar ratio of p-hydroxybenzoic acid unit to 6-hydroxy-2-naphthoic acid unit: 73/27), and has a melting point of 280 ° C. A thermoplastic liquid crystal polymer was melt-extruded, and a film having a film thickness of 50 μm and a melting point of 280 ° C. was obtained by an inflation film molding method while controlling the longitudinal and lateral stretch ratios. The obtained film was further left to stand in a hot air dryer at 260 ° C. for 3 hours for heat treatment to obtain a film having a melting point of 290 ° C. This film is used as a base film, and a 18 μm thick copper foil is set on the top and bottom of the base film. After holding the press temperature at 290 ° C., the press pressure at 4 MPa, and the press time for 60 minutes, cooling to 100 ° C. to release the press pressure A copper-clad laminate was obtained. Furthermore, the printed circuit was processed into a printed wiring board according to the evaluation pattern of IPC B-25.

  A copolymer of p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid (molar ratio of p-hydroxybenzoic acid unit to 6-hydroxy-2-naphthoic acid unit: 73/27), and has a melting point of 280 ° C. A thermoplastic liquid crystal polymer was melt-extruded, and a film having a film thickness of 25 μm and a melting point of 280 ° C. was obtained by an inflation molding method while controlling the longitudinal and lateral stretch ratios. Perforations with a diameter of 20 mm were arbitrarily opened in this film and used as a coverlay film.

(Create flexible printed wiring board)
The above release film, coverlay film, printed wiring board, and release film are laminated in this order as one set, 10 sets are placed on a hot press plate, press temperature 280 ° C., press pressure 2 MPa, press time 60 minutes After being held at, after vacuum press molding under the condition of cooling to 100 ° C. and releasing the press pressure, the release film was peeled off to obtain a flexible printed wiring board. Table 6 shows the releasability of the release film and the circuit dimension change rate of the flexible printed wiring board.

(Example 2)
As the ultrahigh molecular weight polyolefin film layer, the degree of molecular orientation SOR is 1.02, the average thermal expansion coefficient is −85.4 × 10 ⁻⁶ cm / cm / ° C., and the shear modulus at the hot press lamination temperature is 1.5. × 10 ⁵ Pa ultra high molecular weight polyethylene sheet (manufactured by Sakushin Kogyo Co., Ltd., “Saxin New Light Film Innovate”, thickness 30 μm) and a reinforcing layer with an average thermal expansion coefficient of 27 × 10 ⁻⁶ cm A flexible printed wiring board in the same manner as in Example 1 except that a release film is formed by superimposing a polyimide film (Toray Dupont Co., Ltd., “Kapton H”, thickness 25 μm) at / cm / ° C. Got. Table 6 shows the releasability of the release film and the circuit dimension change rate of the flexible printed wiring board.

(Comparative Example 1)
Instead of the ultra-high molecular weight polyolefin film layer, the degree of molecular orientation SOR is 1.20, the average coefficient of thermal expansion is 270 × 10 ⁻⁶ cm / cm / ° C., and the shear modulus at hot press lamination temperature is 1 × 10 ^5. A flexible printed wiring board was obtained in the same manner as in Example 1 except that a release film was formed using a high-density polyethylene sheet of Pa (made by Okura Kogyo Co., Ltd., thickness: 100 μm). Table 6 shows the releasability of the release film and the circuit dimension change rate of the flexible printed wiring board.

(Comparative Example 2)
Instead of the ultra-high molecular weight polyolefin film layer, the degree of molecular orientation SOR is 1.00, the average coefficient of thermal expansion is 100 × 10 ⁻⁶ cm / cm / ° C., and the shear modulus at the hot press lamination temperature is 1 × 10 ^8. A flexible printed wiring board was obtained in the same manner as in Example 2 except that a release film was formed using a fluororesin sheet (Nitto Denko Co., Ltd., “Nitoflon”, thickness 100 μm) that was Pa. Table 6 shows the releasability of the release film and the circuit dimension change rate of the flexible printed wiring board.

(Comparative Example 3)
As the ultra-high molecular weight polyolefin film layer, the molecular orientation degree SOR is 1.00, the average thermal expansion coefficient is 245 × 10 ⁻⁶ cm / cm / ° C., and the shear elastic modulus at the hot press lamination temperature is 1 × 10 ⁶ Pa. A flexible printed wiring board was obtained in the same manner as in Example 1 except that a release film was formed using a certain ultrahigh molecular weight polyethylene sheet (manufactured by Sakushin Kogyo Co., Ltd., “Saxin New Light”, thickness 75 μm). . Table 6 shows the releasability of the release film and the circuit dimension change rate of the flexible printed wiring board.

(Comparative Example 4)
As the ultrahigh molecular weight polyolefin film layer, the molecular orientation degree SOR is 1.00, the average thermal expansion coefficient is 295 × 10 ⁻⁶ cm / cm / ° C., and the shear elastic modulus at the hot press lamination temperature is 2 × 10 ⁶ Pa. A flexible printed wiring board was obtained in the same manner as in Example 1 except that a release film was formed using a certain ultra-high molecular weight polyethylene sheet (manufactured by Yodogawa Hutech Co., Ltd., “UPE”, thickness 100 μm). Table 6 shows the releasability of the release film and the circuit dimension change rate of the flexible printed wiring board.

(Comparative Example 5)
Ultrahigh molecular weight polyethylene sheet having a molecular orientation SOR of 1.00, an average thermal expansion coefficient of 295 × 10 ⁻⁶ cm / cm / ° C., and a shear modulus of 2 × 10 ⁶ Pa at the hot press lamination temperature A flexible printed wiring board was obtained in the same manner as in Example 1 except that the release sheet was formed only by “UPE” (manufactured by Co., Ltd., thickness 100 μm). Table 6 shows the releasability of the release film and the circuit dimension change rate of the flexible printed wiring board.

  As shown in Table 6, in Example 1 and Example 2, since a resin layer having a specific thermal expansion coefficient and a reinforcing layer were combined, even when hot press molding was performed, the circuit dimensional change rate was low, and the hot press The dimensional stability of the circuit board before and after molding can be improved. On the other hand, in Comparative Examples 1 to 5, the circuit dimension change rate by hot press molding is higher than that of the example, and even when the circuit dimension has not changed, the rate of change is the same as in Examples 1 and 2. The circuit dimensions changed by more than 3 times.

Claims (12)

Printed wiring board using film comprising thermoplastic liquid crystal polymer forming optically anisotropic melt phase as (i) substrate, (ii) coverlay film, or (iii) both substrate and coverlay film In the manufacturing process of, a release film used when performing hot press molding,
The release film comprises an ultra-high molecular weight polyolefin film layer and a reinforcing layer superimposed,
The ultrahigh molecular weight polyolefin film layer has a molecular orientation degree SOR in the longitudinal direction of the film in the range of 0.95 or more and less than 1.05, and the average of the thermal expansion coefficient in the plane direction of the film is a negative value,
The reinforcing layer is a release film in which the average thermal expansion coefficient in the plane direction of the reinforcing layer is a positive value. 2. The release film according to claim 1, wherein the ultrahigh molecular weight polyolefin film layer has an average thermal expansion coefficient (M _UP ) of −1 × 10 ⁻⁶ cm / cm / ° C. or less in the planar direction.   3. The release film according to claim 1, wherein the ultrahigh molecular weight polyolefin constituting the ultrahigh molecular weight polyolefin film layer has a viscosity average molecular weight of 1,000,000 or more. 4. The reinforcing layer according to claim 1, wherein the average thermal expansion coefficient (M _RE ) in the plane direction is in the range of 1 × 10 ⁻⁶ to 30 × 10 ⁻⁶ cm / cm / ° C. 5. Release film.   The release film according to any one of claims 1 to 4, wherein the ultrahigh molecular weight polyolefin film layer has a thickness (A) of 30 to 200 µm.   The release film according to any one of claims 1 to 5, wherein the reinforcing layer has a thickness (B) of 10 to 100 µm.   In any one of Claims 1-6, ratio (B) / (A) of the thickness (B) of the reinforcement layer with respect to the thickness (A) of an ultra high molecular weight polyolefin film layer is 60 / 40-30 / A release film which is 70. A film comprising a thermoplastic liquid crystal polymer that forms an optically anisotropic melt phase is used as (i) a substrate, (ii) a coverlay film, or (iii) both a substrate and a coverlay film, A method of manufacturing a printed wiring board by press molding,
The manufacturing method of the printed wiring board which arrange | positions the release film as described in any one of Claims 1-7 so that a reinforcement layer may contact | connect a press hot board in the case of hot press molding.   9. The hot press molding according to claim 8, wherein the hot press molding is selected from a range not lower than a temperature 15 ° C. lower than the melting point of the thermoplastic liquid crystal polymer forming the optically anisotropic melt phase and not higher than 15 ° C. higher than the melting point. A printed wiring board manufacturing method performed at a temperature.   The method for producing a printed wiring board according to claim 8 or 9, wherein the temperature of hot press molding is 250 to 320 ° C.   The printed wiring board manufactured by the method of any one of Claims 8-10. A film comprising a thermoplastic liquid crystal polymer that forms an optically anisotropic melt phase to form a printed wiring board, a coverlay film, or both a substrate and a coverlay film;
Placed above and below the wiring board or the coverlay film so as to sandwich the printed wiring board or the coverlay film, in combination with a reinforcing layer whose average thermal expansion coefficient in the plane direction of the reinforcing layer is a positive value An ultra-high molecular weight polyolefin film for constituting a release film;
Is a material for laminating for hot press molding that is sandwiched between press hot plates,
The ultrahigh molecular weight polyolefin film layer is a laminate in which the molecular orientation degree SOR in the longitudinal direction of the film is in the range of 0.95 or more and less than 1.05, and the average of the thermal expansion coefficient in the plane direction of the film is a negative value Materials.