JPH1067027A - Release film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the releasability with an adhesive resin and to suppress the protrusion of the resin by specifying the tensile elongation at break of a tetrafluoroethylene copolymer film. SOLUTION: A tetrafluoroethylene type copolymer film is used as a release film. A tetrafluoroethylene type copolymer is a copolymer of tetrafluoroethylene and other copolymer component. The content ratio of a polymer unit based on tetrafluoroethylene in the tetrafluoroethylene type copolymer is set according to the kind of the other copolymer component but may be usually set to 30-70mol%, pref., 40-60mol%. The tensile elongation at break of the tetrafluoroethylene type copolymer film at 200 deg.C is 100% or more, pref., 200% or more. By this constitution, the protrusion of a resin is suppressed and the release film can be easily peeled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a release film used for manufacturing a multilayer printed wiring board including an interstitial via hole (hereinafter, referred to as IVH).

[0002]

2. Description of the Related Art In recent years, in multilayer printed wiring boards,
I that expands the space used for wiring and enables high-density mounting
The use of VH is expanding. IVH is a through hole that penetrates between two or more layers of conductors of a multilayer printed wiring board and does not penetrate the entire multilayer printed wiring board.

[0003] There are two types of IVHs: blind via holes in which the presence of through holes can be seen from the surface of the wiring board, and buried via holes which completely enter the multilayer wiring board and cannot be seen from the surface of the wiring board. There are types. In each case, after the step of plating through holes after drilling holes in the wiring board, lamination with a copper foil or another wiring board is performed using an adhesive prepreg.

[0004] This lamination is generally performed by heating and pressing a wiring board using a press machine. At this time, in order to prevent contamination of the stainless steel flat prepreg of the press machine by resin, the stainless steel board is pressed. Heat and pressure are applied between the flat surface and the surface of the laminated wiring board via a release film.

Conventionally, in the step of laminating a multilayer printed wiring board including a blind via hole or a buried via hole, a polymethylpentene resin film,
A vinyl fluoride resin film has been used as a release film.

[0006]

However, these films have poor releasability from the resin of the prepreg which contacts the release film through the inside of the through-hole, and has a 180 to 22 degree.
Due to lack of elongation at a high temperature of 0 ° C., after the through-hole plating step, when prepreg is used for lamination pressing with copper foil or other wiring boards, the adhesive that flows while filling the inside of the through-hole The resin protrudes greatly to the surface layer where the printed wiring pattern is formed and cures,
There were many protrusions of the so-called resin.

For this reason, it is necessary to polish and remove the resin protruding from the laminating step, and this step is complicated and the substrate itself may be deformed in the polishing step.

Further, when a wiring board having a printed wiring pattern formed on the surface in advance is used as the outermost layer, the release film does not stretch at high temperatures, so it does not follow the unevenness of the surface layer, and the above-mentioned resin There was a problem of protrusion and damage to the printed wiring pattern.

The present invention has excellent mold releasability with an adhesive resin flowing while filling the inside of a blind via hole or a buried via hole, which can not be achieved by conventional techniques, and can suppress the resin from protruding. Also provided is a release film used in producing a multilayer printed wiring board which can prevent damage to a printed wiring pattern.

[0010]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, used a film of a tetrafluoroethylene-based copolymer as a film, and obtained the film at 200 ° C. By setting the tensile elongation at break to 100% or more, it has been found that the resin has excellent releasability from the adhesive resin, can suppress the protrusion of the resin, and does not damage the printed wiring pattern, thereby completing the present invention. The present invention is the following film and a method for producing a multilayer printed wiring board using the same.

The tensile elongation at break at 200 ° C. is 100
% Of a tetrafluoroethylene-based copolymer for the production of a multilayer printed wiring board containing IVH.

In a method of manufacturing a multilayer printed wiring board containing IVH by heating and pressurizing a printed wiring board material laminate, at least the surface of the material laminate having holes is reduced to 200
A method for producing a multilayer printed wiring board, wherein the multilayer printed wiring board is covered with a release film made of a film of a tetrafluoroethylene copolymer having a tensile elongation at break of 100% or more and heated and pressed.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION As the release film of the present invention, a film of a tetrafluoroethylene copolymer is used. The tetrafluoroethylene-based copolymer is a copolymer of tetrafluoroethylene and another copolymer component. Examples of other copolymer components include olefins such as ethylene and propylene, hexafluoropropylene, and perfluoro (alkyl vinyl ether). As the tetrafluoroethylene-based copolymer, these other copolymer components can be used alone or in combination of two or more.

Specific examples of the tetrafluoroethylene-based copolymer include a tetrafluoroethylene-perfluoro (alkyl vinyl ether) -based copolymer (hereinafter referred to as PFA).
), Tetrafluoroethylene-ethylene-based copolymer (hereinafter, referred to as ETFE), tetrafluoroethylene-hexafluoropropylene-based copolymer (hereinafter, FEP)
Is preferred.

As ETFE, CF ₂ CF ₃ CF = CF in order to improve the tensile elongation at break at 200 ° C.
_{2, HCF 2 C 3 F 6} CH = CH 2, or, n-C ₄
A copolymer obtained by copolymerizing a third component such as F ₉ CH ＝ CH ₂ is preferable, and particularly, n-C ₄ F ₉ CH ＝ CH is used as the third component.
_A copolymer obtained by copolymerizing ₂ is preferred. Third component, especially n
The content of _{-C 4 F 9 CH = CH 2} , in based polymerized units is preferably 0.2 to 10 mol%.

The content of the polymerized units based on tetrafluoroethylene in the tetrafluoroethylene-based copolymer depends on the type of other copolymerization components, but is usually from 30 to 70.
Mol%, preferably 40 to 60 mol%.

The tensile elongation at break of the film of the above tetrafluoroethylene copolymer at 200 ° C. is 100%.
Or more, preferably 200% or more. Although the upper limit of the tensile elongation at break of the film is not particularly limited, it is preferably within 600%, particularly preferably within 500%. The tensile elongation at break is a tensile elongation at break at 200 ° C. measured according to ASTM (American Society for Testing and Materials) D638.

The release film of the present invention preferably has a contact angle with water of 85 ° or more as an index of releasability from the adhesive resin, particularly preferably 90 to 115 °. .

Further, as the release film of the present invention, a film in which an antistatic agent is kneaded into the film at about 0.1 to 2% for imparting antistatic properties can be used. Further, the release film of the present invention, other additives, for example, may be blended with an inorganic filler, and other resins, for example, to improve the flexibility of the film, fluorine rubber, for example, tetrafluoroethylene -A propylene-based copolymer, a vinylidene fluoride-hexafluoropropylene-based copolymer, or the like may be blended.

The release film of the present invention has a thickness of 20 to 20.
0 μm is suitable, and particularly preferably 25 to 100 μm. Shape of the surface of the release film of the present invention is preferably from planar, embossed about average surface roughness R _a is 0.5 to 2 [mu] m, can be used films raised handling properties.

The release film of the present invention can be produced by various film forming methods such as extrusion, pressure forming and cast film forming. The release film can be used without stretching, but may be subjected to uniaxial stretching or biaxial stretching.

The release film of the present invention can be applied to various manufacturing methods for manufacturing a multilayer printed wiring board including a blind via hole or a buried via hole. The multilayer printed wiring board only needs to include one of a blind via hole or a buried via hole,
Both of them may be included.

When manufacturing a multilayer laminate containing IVH, a sequential lamination method or the like in which through-plated partial laminates are sequentially stacked is often used.

In the present invention, the printed wiring board material means the following substrate, copper foil, adhesive prepreg and the like. These are appropriately stacked and laminated according to the purpose, and the surface is covered with the release film and heated and pressed to obtain a multilayer printed wiring board. If the release film has at least this hole on both sides of the laminate of the printed wiring board material,
Both sides are covered with the release film. When one surface does not have a hole, the surface having no hole may be covered with the release film of the present invention, or may be covered with another release film.

The substrate of the multilayer printed wiring board used in these multilayer printed wiring board manufacturing methods is made of a woven or non-woven fabric such as a cellulosic fiber paper or glass fiber as a base material.
This is impregnated with a thermosetting resin and cured.
Suitable substrate materials include, for example, glass fiber-epoxy resin composite, glass fiber-polyimide resin composite, and glass fiber-maleimide-triazine resin composite material. In order to adhere these substrates to each other or to a copper foil or a copper foil provided with a printed wiring pattern, a prepreg in which a resin of the same material as the material used for the substrate is in a semi-cured state is used. Can be

The adhesive prepreg is prepared by impregnating a base material with an uncured thermosetting resin and, if necessary, a curing agent and a solvent.
It can be manufactured by drying at 30 to 200 ° C. for 3 to 5 minutes. The semi-cured state of the thermosetting resin of the adhesive prepreg is preferred. This state can be controlled from the gel time, but the gel time at 170 ° C. is 100 to 300 seconds for the glass fiber-epoxy resin composite, and 200 to 400 seconds for the glass fiber-polyimide resin composite. is there.

A multilayer printed wiring board can be manufactured by laminating substrates, copper foils, adhesive prepregs and the like, disposing release films on both sides of the laminate, and applying heat and pressure. The conditions for heating and pressurizing are usually as follows:
Preferably, it is in the range of 180 to 220 ° C. and the pressure is 5
５０50 kg / cm ² , preferably 20-30 kg / cm
^The pressurizing time may be in the range of 30 to 240 minutes, preferably 40 to 120 minutes.

At the time of heating and pressurizing, pressing may be performed in a state in which both are directly in contact with each other without any intervening between the release film and the press hot plate. Pressing may be performed with a rubber plate interposed therebetween. The material of the press hot plate is preferably stainless steel.

[0029]

EXAMPLES Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

[Example 1] A glass fiber-epoxy resin composite substrate was used as a substrate material.
A layer printed wiring board was manufactured as follows.

A double-sided copper-clad laminate composed of a copper foil layer 2, a copper foil layer 3, and a cured glass fiber-epoxy resin composite insulator 1 was drilled as shown in FIG. , And a plating solution comprising copper, ethylenediaminetetraacetic acid and formaldehyde was passed through the portion, and through-hole plating 4 was performed.

Subsequently, after a printed wiring pattern was formed on the copper foil layer 2 and the copper foil layer 3, a blackening treatment was performed on the copper foil layer 2, the copper foil layer 3 and the through-hole plating 4. This blackening treatment is a treatment for generating copper oxide on the surface of the copper foil, and can increase the adhesiveness with the adhesive prepreg.

Next, as shown in FIG. 2, this substrate and the copper foil layer 8 are subjected to the first multi-layer lamination using the adhesive prepreg 7, and the release film 5 is placed outside the copper foil layer 2. The release film 6 was placed outside the copper foil layer 8 to form a blind via hole A '. The conditions for heating and pressing are 190
° C, pressure 30 kg / cm ² , time 40 minutes.

At this time, the resin of the adhesive prepreg 7 flows,
As shown in FIG. 3, the hole of the through-hole plating 4 went up, but remained at a height of only about 0.2 μm from the height of the copper foil layer 2, and the so-called resin did not protrude substantially. Therefore, the step of polishing and removing the protruding portion was completed once. Further, the release film could be easily peeled off. Further, the copper foil layer 2 was not damaged.

The release film 5 and the release film 6 used at this time were ETFE (polymerized units based on ethylene / polymerized units based on tetrafluoroethylene / CH ₂ =
Polymerized units based on CH-C ₄ F ₉ (molar ratio) 47/5
3 / 0.7), a release film having a thickness of 50 μm, a water contact angle of 95 °, and a tensile elongation at break at 200 ° C. in accordance with ASTM D638 of 260%.

Subsequently, as shown in FIG. 4, a hole B was drilled so as to penetrate the copper foil layer 2, the copper foil layer 3, and the copper foil layer 8, and a through-hole plating 9 was applied to the portion to perform catabolic treatment.

Next, a printed wiring pattern was formed on the copper foil layer 11 and the copper foil layer 13 of the double-sided copper clad board prepared in advance, and thereafter a hole C was drilled, and a through-hole plating 14 was applied to the hole C. Subsequently, the copper foil layer 11,
The copper foil layer 13 and the through-hole plating 14 were blackened.

Next, as shown in FIG. 5, a laminate comprising the copper foil layer 13 and the copper foil layer 11 and the cured glass fiber-epoxy resin composite insulator 12 and the copper foil layer 2 and the copper foil layer 3. A second multi-layer lamination is performed by using an adhesive prepreg 10 with a three-layer substrate made of a copper foil layer 8, and a release film 5 and a release film 6 are formed outside the copper foil layer 13 and the copper foil layer 2. Then, heating and pressurizing were performed to form blind via holes B ′ and C ′. Heating and pressing conditions are 190 ° C,
The pressure is 30 kg / cm ² and the time is 40 minutes.

At this time, the resin of the adhesive prepreg 10 flows and rises up through the holes of the through-hole platings 9 and 14, but as shown in FIG. And remained at a height of about 0.2 μm with respect to the height of the copper foil layer 13. Therefore, the step of polishing and removing the protruding portion was completed once. Moreover, the release films 5 and 6 could be easily peeled off. The copper foil layer 2 and the copper foil layer 13 were not damaged.

Example 2 Example 1 was the same as Example 1, except that the release films 5 and 6 were 25 μm FEP resin films (Toyoflon FEP, trade name, manufactured by Toray Synthetic).
In the same manner as in the above, two multilayer laminations were performed. The release films 5 and 6 had a tensile elongation at break of 200% at 150 ° C. and a water contact angle of 110 °.

In the first multi-layer lamination, the resin of the adhesive prepreg 7 protruded from the copper foil layer 2 to a height of 1 μm. Therefore, in order to remove the protruding portion by polishing,
It was only necessary to perform the polishing process twice. The release film could be easily peeled off. The copper foil layer 2 was not damaged.

Also in the second multilayer lamination, the resin of the adhesive prepreg 10 is 1 μm higher than the copper foil layer 2,
It protruded by about 1 μm with respect to the height of the copper foil layer 13. Therefore, it is sufficient to perform only three polishing steps in order to polish and remove the protruding portion. The release film could be easily peeled off. The copper foil layer 2 and the copper foil layer 13 were not damaged.

Comparative Example 1 Two layers were laminated in the same manner as in Example 1 except that the release film in Example 1 was a 25 μm vinyl fluoride resin film (manufactured by DuPont, trade name: Tedlar). went. The release film had a tensile elongation at break of 200% at 200 ° C. and a water contact angle of 80 °.

In the first multi-layer lamination, the resin of the adhesive prepreg 7 protruded from the height of the copper foil layer 2 by 4 μm. Twenty polishing steps were required to remove the protruding portion by polishing. Further, in order to peel off the film, a sufficient force to deform the film was required. However, the copper foil layer 2 was not damaged.

Also in the second multilayer lamination, the resin of the adhesive prepreg 10 is 4 μm higher than the copper foil layer 2,
4 μm protruded from the height of the copper foil layer 13. Therefore, 20 polishing steps were required to remove the protruding portion by polishing. Further, in order to peel off the release films 5 and 6, it was necessary to have enough force to deform the release films. However, the copper foil layer 2 and the copper foil layer 13 were not damaged.

[Comparative Example 2] The release films 5 and 6 were
5 of TFE (polymerized unit based on ethylene / polymerized unit based on tetrafluoroethylene / polymerized unit based on nC ₄ F ₉ CH = CH ₂ (molar ratio) is 47/53 / 0.1)
Except for forming a film having a thickness of 0 μm, two multilayer laminations were performed in the same manner as in Example 1. The water contact angle of this release film is 91 °, and the tensile elongation at break at 200 ° C. is 80%.
Met.

In the first multi-layer lamination, the resin of the adhesive prepreg 7 protruded from the height of the copper foil layer 2 by 1 μm. Therefore, in order to remove the protruding portion by polishing,
Polishing steps were required. The release film could be easily peeled off, but the copper foil layer 2 was slightly scratched.

Also in the second multi-layer lamination, the resin of the adhesive prepreg 10 protruded from the height of the copper foil layer 2 by 1 μm and protruded by about 1 μm from the height of the copper foil layer 13. Therefore, three polishing steps were required to remove the protruding portion by polishing. Further, the release film could be easily peeled off, but the copper foil layer 2 and the copper foil layer 13 were slightly scratched.

[0049]

When a multilayer printed wiring board including a blind via hole or a buried via hole is manufactured using the release film of the present invention, it is possible to suppress the protrusion of the adhesive resin and to have excellent release properties. Since the circuit pattern on the surface is not damaged, it is possible to form a multilayer printed wiring board excellent in economy and reliability.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a cured double-sided copper-clad laminate in which a copper foil layer is laminated on both sides of a glass fiber-epoxy resin composite insulator.

FIG. 2 is a schematic sectional view showing a state in which an adhesive prepreg and a copper foil layer are laminated on the double-sided copper-clad laminate of FIG. 1, and a release film is laminated on both surfaces.

FIG. 3 is a schematic sectional view of a multilayer laminate obtained by pressure-molding the multilayer laminate of FIG.

FIG. 4 is a schematic cross-sectional view of the multilayer laminate in which holes are formed in the multilayer laminate of FIG. 3;

5 is a schematic cross-sectional view showing a state in which an adhesive prepreg and a double-sided copper-clad laminate are laminated on the multilayer laminate of FIG. 4, and release films are laminated on both surfaces.

FIG. 6 is a schematic cross-sectional view of a multilayer laminate obtained by pressure-molding the multilayer laminate of FIG.

[Explanation of symbols]

1: glass fiber-epoxy resin composite insulator 2: copper foil layer 3: copper foil layer 4: through hole plating 5: release film 6: release film 7: adhesive prepreg 8: copper foil layer 9: through hole plating 10 : Bonded prepreg 11: Copper foil layer 12: Glass fiber-epoxy resin composite insulator 13: Copper foil layer 14: Through-hole plating A: Hole A ': Blind via hole filled with cured adhesive prepreg B: Hole B' : Blind via hole filled with cured adhesive prepreg C: Hole C ': Blind via hole filled with cured adhesive prepreg

──────────────────────────────────────────────────の Continuation of the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical indication location C08J 5/18 CEW C08J 5/18 CEW H05K 3/20 7511-4E H05K 3/20 A B29K 27: 12

Claims (4)

[Claims] 1. A tensile elongation at break at 200 ° C. of 100
% Of a tetrafluoroethylene-based copolymer having an interstitial via hole. 2. The tetrafluoroethylene-based copolymer is a tetrafluoroethylene-ethylene-based copolymer, a tetrafluoroethylene-hexafluoropropylene-based copolymer, or a tetrafluoroethylene-perfluoro (alkyl vinyl ether) -based copolymer. The release film according to claim 1, which is united. 3. The tetrafluoroethylene-based copolymer is a copolymer of tetrafluoroethylene, ethylene and (perfluorobutyl) ethylene, wherein the polymerization unit based on (perfluorobutyl) ethylene is 0.2 to 10 mol. %
The release film according to claim 1, comprising: 4. A method for producing a multilayer printed wiring board including interstitial via holes by heating and pressurizing a printed wiring board material laminate, wherein at least a surface of the material laminate having holes is subjected to tensile breaking elongation at 200 ° C. A method for producing a multilayer printed wiring board, comprising covering with a release film made of a film of a tetrafluoroethylene copolymer having a degree of 100% or more and heating and pressing.