JP2007070418A - Adhesive sheet, metal foil-clad laminated sheet and built-up type multilayered printed wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an adhesive sheet having high heat resistance and electric insulation reliability in high humidity, also having little variation in thermal expansion coefficient and sheet thickness, capable of providing a laminated sheet and a printed wiring board having good moldability, and obtained by using an organic base material. <P>SOLUTION: The adhesive sheet is obtained by using a film comprising a liquid crystal polymer containing a whole aromatic polyester such as a condensate of p-hydroxybenzoic acid and 1,6-hydroxynaphthoic acid, and a copolymer thereof as the base material, and forming a resin layer on the surface of the base material. The metal foil-clad laminated sheet and the printed wiring board are obtained by using the adhesive sheet. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an adhesive sheet used as a material for a printed wiring board, a metal-clad laminate formed using the adhesive sheet, and a build-up type multilayer printed wiring board.

  Conventionally, a printed wiring board on which a semiconductor device or the like is mounted is stored in an electronic device. As a metal foil-clad laminate for producing this printed wiring board, an epoxy resin prepreg based on a glass cloth and copper are used. A glass cloth base epoxy resin copper clad laminate produced using a foil is widely used.

However, in recent years, a prepreg using an organic fiber non-woven fabric as a base material instead of a glass cloth and a copper-clad laminate formed by laminating the prepreg in order to reduce the weight, reduce the dielectric constant, and improve the laser processability. As a representative organic fiber, an aramid (fully aromatic polyamide) fiber or a fully aromatic polyester fiber having characteristics of high strength and excellent heat resistance is used (see Patent Document 1).
JP 2004-352845 A

  However, since aramid fibers have higher hygroscopicity than glass fibers, there is a problem that heat resistance and electrical insulation reliability under moisture absorption of laminated boards and printed wiring boards based on aramid nonwoven fabrics are low. .

  In addition, fully aromatic polyester fibers improve the above-mentioned drawbacks of aramid fibers. However, since they contain a large amount of resin when used as a prepreg, the coefficient of thermal expansion tends to increase, and low thermal expansion is required for packaging applications. It was insufficient for the intended use.

  Therefore, the present invention has been made in view of the above problems, and has high heat resistance and electrical insulation reliability under moisture absorption, small variations in thermal expansion coefficient and plate thickness, and good moldability. It is an object of the present invention to provide an adhesive sheet using an organic base material capable of obtaining a laminate and a printed wiring board, a copper-clad laminate using the adhesive sheet, and a printed wiring board.

  As a result of intensive research aimed at achieving the above object, the present inventors can achieve the above object by using a film made of a liquid crystal polymer containing a wholly aromatic polyester as a base material for the adhesive sheet. I found.

  That is, the adhesive sheet of the present invention is characterized in that a film made of a liquid crystal polymer containing wholly aromatic polyester is used as a base material and a resin layer is formed on the surface of the base material.

  In addition, the metal foil-clad laminate of the present invention is characterized by having an insulating layer formed by heating and pressing the adhesive sheet of the present invention.

  Moreover, the printed wiring board of this invention has an insulating layer formed by heat-press-molding the adhesive sheet of this invention, It is characterized by the above-mentioned.

  According to the present invention, an adhesive sheet having excellent heat resistance, moisture resistance, and corrosion resistance and having a low coefficient of thermal expansion can be provided by using a film made of a liquid crystal polymer containing a wholly aromatic polyester as a substrate. Further, by using this adhesive sheet, it is possible to produce a metal foil-clad laminate and a printed wiring board that are excellent in heat resistance and moisture resistance and are also resistant to heat changes.

  Hereinafter, the present invention will be described in detail with reference to the drawings.

  First, FIG. 1 shows a cross-sectional view of a laminated board in which metal foil is provided on both surfaces of the adhesive sheet of the present invention.

  The adhesive sheet 1 of the present invention is characterized in that a film 2 made of a liquid crystal polymer containing a wholly aromatic polyester is used as a base material, and a resin layer 3 is formed on the surface of the base material. Here, the metal foil 4 is provided on both surfaces of the adhesive sheet 1.

  The film 2 made of a liquid crystal polymer containing a wholly aromatic polyester is preferably formed only from a wholly aromatic polyester, but may be a liquid crystal polymer containing the wholly aromatic polyester as a main component.

  Moreover, it is preferable that the film 2 which consists of this liquid crystal polymer is negative in the range of 25-200 degreeC of the thermal expansion coefficient of the plane direction under a normal pressure, and it is especially preferable that it is negative in all the ranges. When the thermal expansion coefficient is negative in this way, the overall thermal expansion coefficient when used as a wiring board can be greatly reduced, and the connection reliability with electronic components such as semiconductor elements having a low thermal expansion coefficient can be improved. It can be greatly improved.

  Furthermore, the film 2 made of a liquid crystal polymer preferably has a thickness in the range of 10 to 200 μm. When the thickness is less than 10 μm, the thermal expansion coefficient in the planar direction is controlled by the thermal expansion coefficient of the resin, and the mounting position of the semiconductor or the like is shifted. When the thickness exceeds 200 μm, the thickness direction of the film made of a liquid crystal polymer Due to the thermal expansion change, the through conductor formed in the thickness direction is disconnected.

  The film 2 made of the liquid crystal polymer can be easily formed by melt-extruding the liquid crystal polymer, and can be obtained as a film excellent in chemical resistance, water resistance, and heat resistance by forming into a film in this way. .

The wholly aromatic polyester used as a component of the film made of the liquid crystal polymer is an aromatic polyester that does not have an aliphatic hydrocarbon in the main chain, and is composed of p-hydroxybenzoic acid (HBA) and 6-hydroxynaphthoene. A copolymer of an acid (HNA) (specifically, for example, “Bexstar OCL” manufactured by Kuraray Co., Ltd.) and the like, an aromatic diol and an aromatic dicarboxylic acid and / or an aromatic hydroxycarboxylic acid. Copolymers reacted in appropriate combinations can be used.
Next, the resin layer 3 formed on the substrate surface of the film 2 can be formed by applying a liquid resin composition to the surface of the film 2 made of a liquid crystal polymer formed by melt extrusion and drying. it can.

  This resin layer 3 functions as an adhesive layer for bonding a metal foil such as a copper foil, and its thickness is 5 to 20 μm, which is thinner than the thickness of the film 2 made of a liquid crystal polymer. Is preferred. If it is thicker than the film 2, the thermal expansion coefficient of the resin is dominant and the thermal expansion coefficient of the adhesive sheet increases, which may hinder the connection reliability at the connection part of the electronic component on the surface of the wiring board.

  Here, as the resin that can be used for the resin layer 3, in addition to thermosetting resins such as epoxy resins and modified polyimide resins, thermoplastic resins such as PPE (polyphenylene ether) can also be used. Especially, it is preferable that it is an epoxy resin with favorable adhesiveness. Moreover, it is preferable that the resin composition used for this adhesive sheet is halogen-free.

  As a more specific combination of the components of this epoxy resin composition, it is preferable that (A) an epoxy resin, (B) a curing agent for epoxy resin, and (C) a curing accelerator are essential components, Further, (D) an inorganic filler may be contained.

  Here, each component of the epoxy resin composition will be described in detail.

  The (A) epoxy resin used in the present invention is not particularly limited as long as it is an epoxy resin having two or more epoxy groups in one molecule. For example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, novolak type Epoxy resin, glycidyl ether type epoxy resin, alicyclic epoxy resin, heterocyclic epoxy resin, etc., polyfunctional epoxy resin containing biphenyl skeleton, or a mixture of two or more of these Things can be used.

  Moreover, when imparting flame retardancy to an adhesive composition, it can be achieved by providing a general flame retardant mechanism by using, for example, a phosphorus-modified epoxy resin as an epoxy resin.

  These epoxy resins can usually be used after being dissolved in a solvent. As the solvent, an epoxy resin, a curing agent for epoxy resin, a curing accelerator for epoxy resin, and an inorganic filler can be used. It is preferable that the boiling point is 160 ° C. or lower so that no solvent remains in the adhesive coating and drying step.

  Specific examples of the solvent include methyl ethyl ketone, toluene, acetone, ethyl cellosolve, methyl cellosolve, and cyclohexanone, and these can be used alone or in combination of two or more.

  The (B) epoxy resin curing agent used in the present invention can be used without particular limitation as long as it is a compound usually used for curing epoxy resins. Examples of amine curing systems include dicyandiamide and aromatic compounds. Phenolic curing systems include phenol novolak resins, cresol novolak resins, bisphenol A type novolak resins, triazine-modified phenol novolak resins, etc., and these should be used alone or in combination of two or more. Can do.

  The (C) curing accelerator used in the present invention is usually used as an epoxy resin curing accelerator, and is an imidazole compound such as 2-ethyl-4-imidazole or 1-benzyl-2-methylimidazole. , Boron trifluoride amine complex, triphenylphosphine and the like. These curing accelerators can be used alone or in combination.

  The inorganic filler (D) used in the present invention is not particularly limited as long as it has excellent heat dissipation and insulation, and examples thereof include silicon oxide, aluminum oxide, silicon carbide, and aluminum nitride. These inorganic fillers can be used alone or in admixture of two or more.

  The blending ratio of (A) to (C), which is a constituent component of the adhesive composition used in the present invention, can be used at a blending ratio in the following range with respect to 100 parts by mass of (A) epoxy resin. B) The curing agent for epoxy resin is preferably in the range of 2 to 50 parts by mass, and (C) the curing accelerator is preferably in the range of 0.01 to 5 parts by mass. At this time, the blending amount of the curing agent for (B) epoxy resin reacts with the equivalent ratio of (A) epoxy resin and (B) curing agent for epoxy resin, that is, the epoxy group of the curing agent with respect to the number of epoxy groups. The ratio of the number of functional groups (amine groups, hydroxyl groups, etc.) is particularly preferably in the range of 0.5 to 1.5.

  Moreover, it is preferable that the compounding ratio of (D) inorganic filler used for this invention is 70 volume% or less in an adhesive composition, and it is more preferable that it is 10-70 volume%. If this blending ratio exceeds 70% by volume, the adhesive strength of the resin layer will be insufficient.

  Furthermore, in addition to these components, when imparting flame retardancy, phosphorus compounds and metal hydrates can be added, and if necessary, finely divided inorganic or organic fillers and pigments Further, deterioration inhibitors, elastomers, and the like can be added and blended within a range that does not impair the effects of the present invention.

  The resin composition of the present invention composed of the components described above is diluted with a suitable organic solvent such as methyl ethyl ketone, toluene, acetone, ethyl cellosolve, methyl cellosolve, cyclohexanone to form a resin solution, and this is impregnated into a fiber base material. An adhesive sheet can be manufactured by drying.

  Next, the manufacturing method of the adhesive sheet of this invention is demonstrated.

  In the present invention, the resin layer can be formed on the surface of the base material by applying a liquid resin composition to the surface of the film 2 made of a liquid crystal polymer and drying it. As the resin composition, a thermosetting resin is used. Can be used, the resin can be B-staged by heating during drying. At this time, the resin composition is dissolved in a solvent to prepare a varnish, and this varnish is generally applied to a film and dried to form a B stage. It is not something.

And, the thermal expansion coefficient of the adhesive sheet after curing the adhesive layer formed of the resin composition is preferably 30 × 10 ⁻⁶ / ° C. or less in a temperature range of 25 to 200 ° C. under normal pressure. It is particularly preferable that the temperature is 30 × 10 ⁻⁶ / ° C. or lower in the entire temperature range. Furthermore, the coefficient of thermal expansion is more preferably in the range of 0 to 10 × 10 ⁻⁶ / ° C.

  The metal foil-clad laminate of the present invention is formed by laminating a plurality of adhesive sheets obtained as described above, and heating and pressing a metal foil such as a copper foil on one or both sides. .

  Furthermore, the printed wiring board of the present invention is formed by, for example, laminating a plurality of the above-mentioned adhesive sheets on one side on a glass cloth inner layer board (FR-4) or the like to form a build-up structure, and heating and pressing this. It is an up-type multilayer printed wiring board.

  The heating and pressing conditions for producing the metal foil-clad laminate and the multilayer printed wiring board vary depending on the type of resin of the prepreg, but in the case of an epoxy resin, for example, the temperature is around 200 ° C., the pressure is 2 to 5 MPa, The time can be set to 60 to 120 minutes, respectively, and at this time, the adhesive sheet functions as an insulating layer.

  The metal foil-clad laminate of the present invention uses a wholly aromatic polyester film whose thermal expansion coefficient is much smaller than that of a wholly aromatic polyester fiber substrate, and a resin is applied to the surface of the substrate. Since the manufactured adhesive sheet is used, a moisture absorption rate can be made small as a laminated board, and the heat-resistant fall and insulation resistance fall by moisture absorption can be prevented.

  Similarly, the build-up type multilayer printed wiring board of the present invention has a fully aromatic polyester film whose thermal expansion coefficient is much smaller than that of a fully aromatic polyester fiber substrate, and the surface of this substrate. Since the adhesive sheet manufactured by coating the resin is used, it is possible to reduce the moisture absorption rate as a multilayer printed wiring board, and it is possible to prevent a decrease in heat resistance and a decrease in insulation resistance due to moisture absorption.

  Furthermore, as a resin composition used for the adhesive sheet of the present invention, if a halogen-free epoxy resin is used, an adhesive sheet that does not generate toxic gas such as hydrogen bromide during combustion, a metal foil-clad laminate, and a multilayer print A wiring board can be obtained.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited by these Examples. In the following Examples and Comparative Examples, “part” means “part by mass”.

(Reference Example 1)
300 parts of HP-7200 (trade name, manufactured by Dainippon Ink Co., Ltd.) of dicyclopentadiene type epoxy resin, 260 parts of MEH-7851 (trade name, manufactured by Meiwa Kasei Co., Ltd.) of biphenyl type phenol novolak resin, 0.1% of imidazole Methyl ethyl ketone was added to the resin composition consisting of parts to prepare varnish 1 having a solid content of 65% by mass.

(Reference Example 2)
Varnish 2 having a solid content of 65% by mass was prepared in the same manner as in Synthesis Example 1 except that 30% by volume of spherical silica having an average particle size of 0.5 μm was contained in the resin composition.

(Reference Example 3)
300 parts of epoxy resin NC-3000H (trade name, manufactured by Nippon Kayaku Co., Ltd.) having biphenyl skeleton and phenol skeleton, 270 parts of MEH-7851 (trade name, manufactured by Meiwa Kasei Co., Ltd.), biphenyl type phenol novolac resin, imidazole Methyl ethyl ketone was added to a mixture of 0.1 part to prepare varnish 3 having a solid content of 65% by mass.

(Reference Example 4)
NC-7000L of epoxy resin having a naphthol skeleton (product name) manufactured by Nippon Kayaku Co., Ltd., 210 parts of MEH-7851 (product name) manufactured by Biphenyl type phenol novolac resin, 0.1 part of imidazole 0.1 Methyl ethyl ketone was added to the mixture consisting of parts to prepare varnish 4 having a solid content of 65% by mass.

Example 1
A semi-cured state is obtained by coating and heating the varnish 1 on both surfaces of a substrate using a horizontal dryer on a fully aromatic polyester film “BEXTER OCL” (trade name, manufactured by Kuraray Co., Ltd.) having a substrate thickness of 50 μm. An adhesive sheet was obtained.

  Copper foil was laminated on both surfaces of this adhesive sheet, and a copper clad laminate having a thickness of 0.1 mm was produced by pressing and heating at 170 ° C. and 2.5 MPa for 90 minutes.

(Example 2)
A semi-cured state is obtained by coating and heating a varnish 1 on both surfaces of a base material using a horizontal dryer on a 100 μm-thick wholly aromatic polyester film “BEXTER OCL” (trade name, manufactured by Kuraray Co., Ltd.). An adhesive sheet was manufactured.

  Copper foil was laminated on both surfaces of this adhesive sheet, and a copper clad laminate having a thickness of 0.1 mm was produced by pressing and heating at 170 ° C. and 2.5 MPa for 90 minutes.

(Example 3)
An adhesive sheet and a copper clad laminate were produced in the same manner as in Example 1, except that varnish 2 was used for a fully aromatic polyester film “BEXTER OCL” (trade name, manufactured by Kuraray Co., Ltd.) having a substrate thickness of 50 μm. did.

(Examples 4 to 5)
The adhesive sheet and the copper-clad laminate were prepared in the same manner as in Example 1 except that varnishes 3 and 4 were respectively used for a 100 μm base aromatic polyester film “BEXTER OCL” (trade name, manufactured by Kuraray Co., Ltd.). A board was produced.

(Comparative Examples 1-3)
Fully aromatic polyester wet process nonwoven fabric “Vectran HRBE-40” (manufactured by Kuraray Co., Ltd., trade name: fiber density 0.4 g / cm ³ ) impregnated with varnishes 1, 3, and 4 using vertical dryers, respectively. -A prepreg having a resin content (resin amount) of 68% was produced by heating and pressing.

  Copper foils were stacked on both sides of this prepreg and pressed and heated at 170 ° C. and 2.5 MPa for 90 minutes to produce a copper clad laminate having a thickness of 0.1 mm.

(Comparative Examples 4-5)
As general copper-clad plates, halogen-free flexible copper-clad plates (Kyocera Chemical Co., Ltd., trade name: TFL-W-510GR), halogen-free copper-clad laminates (Kyocera Chemical Co., Ltd., trade name: TLC-W-) 552) was used as a comparison.

(Test example)
Properties of the thermal expansion coefficient of the adhesive sheets (prepregs) obtained in Examples 1 to 5 and Comparative Examples 1 to 5, the copper foil peeling strength (normal state) of the copper clad laminate, solder heat resistance, and flame retardancy The results are shown in Tables 1 and 2.

1: Using a thermomechanical analyzer (manufactured by Seiko Instruments Inc., trade name: TMA / SS6000), measurement was performed at a measurement frequency of 1 Hz in a nitrogen atmosphere under a temperature rise condition of 2 ° C./min by the TMA method.
2: Measured according to JIS-C-6481.
3: A sample was floated on a solder bath having the temperature shown in the table for 1 minute, the presence or absence of swelling was observed, and evaluation was performed according to the following criteria.
○: No blistering, x mark: blistering 4: Measured according to UL94 flame retardant test.

It is the figure which showed sectional drawing of the metal foil tension laminated board of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Adhesive sheet, 2 ... Film base material, 3 ... Resin layer, 4 ... Metal foil

Claims (13)

  An adhesive sheet comprising a film made of a liquid crystal polymer containing a wholly aromatic polyester as a base material, and a resin layer formed on the surface of the base material. 2. The adhesive according to claim 1, wherein the thermal expansion coefficient of the adhesive sheet after curing the resin layer is 30 × 10 ⁻⁶ / ° C. or less in a temperature range of 25 to 200 ° C. under normal pressure. Sheet.   The adhesive sheet according to claim 1 or 2, wherein a thermal expansion coefficient in a plane direction of the film is negative in a temperature range of 25 to 200 ° C under normal pressure.   The adhesive sheet according to any one of claims 1 to 3, wherein the wholly aromatic polyester is a condensate of p-hydroxybenzoic acid and 1,6-hydroxynaphthoic acid or a copolymer thereof.   The adhesive sheet according to claim 1, wherein the base material has a thickness of 10 to 200 μm.   The adhesive sheet according to claim 5, wherein a thickness of the resin layer is thinner than a thickness of the base material.   The adhesive sheet according to any one of claims 1 to 6, wherein the resin forming the resin layer is an epoxy resin composition.   8. The epoxy resin composition according to claim 7, comprising (A) an epoxy resin, (B) a curing agent for epoxy resin, (C) a curing accelerator, and (D) an inorganic filler. Adhesive sheet.   The adhesive sheet according to claim 8, wherein the (D) inorganic filler is contained in the resin composition in a proportion of 70% by volume or less.   The adhesive sheet according to any one of claims 1 to 9, wherein the resin forming the resin layer is a halogen-free resin composition.   The adhesive sheet according to claim 9 or 10, wherein the inorganic filler is at least one selected from silicon oxide, aluminum oxide, silicon carbide, and aluminum nitride.   A metal foil-clad laminate comprising an insulating layer formed by heat-pressing the adhesive sheet according to any one of claims 1 to 11.   A build-up type multilayer printed wiring board comprising an insulating layer formed by heating and pressing the adhesive sheet according to claim 1.

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