JP7403061B2 - Method for manufacturing resin sheet with metal foil, printed wiring board, and resin sheet with metal foil - Google Patents

Description

The present invention relates to a method for manufacturing a resin sheet with metal foil, a printed wiring board, and a resin sheet with metal foil, and more specifically, a resin sheet with metal foil in which a metal layer, an insulating resin layer, and an adhesive layer are laminated, and the metal foil. The present invention relates to a printed wiring board manufactured using the metal foil-covered resin sheet, and a method for manufacturing the metal foil-covered resin sheet.

In order to make printed wiring boards multilayered, a metal foil-covered resin sheet in which a metal layer, an insulating resin layer, and an adhesive layer are laminated is sometimes used. For example, Patent Document 1 discloses that the epoxy resin layer in a resin sheet with metal foil is formed by laminating a metal foil, a polyimide film, and an epoxy resin layer in this order on a conductor circuit formed on the surface of a base material, and the conductor circuit is made of epoxy resin. A technique has been disclosed in which a printed wiring board is multilayered by stacking the epoxy resin layers so as to be embedded in the layers and then curing the epoxy resin layer.

JP2010-129610A

However, when the conductor wiring is embedded in an adhesive layer such as the epoxy resin layer disclosed in Patent Document 1, and the thickness of the conductor wiring is large relative to the line width of the conductor wiring, the conductor wiring may reach the metal layer. There is a risk of a short circuit. In particular, when an inductor element is manufactured by forming conductor wiring into a coil shape, the risk of short circuiting increases. Furthermore, when chip components are mounted on conductor wiring and embedded in an adhesive layer, there is a risk that the chip components will come into contact with the metal layer. As printed wiring boards become thinner, the risk of short circuits increases.

An object of the present invention is to provide a resin sheet with a metal foil that is unlikely to cause a short circuit when embedding conductive wiring or chip components in an adhesive layer, a printed wiring board manufactured using the resin sheet with the metal foil, and a resin sheet with the metal foil. An object of the present invention is to provide a method for manufacturing a sheet.

A resin sheet with metal foil according to one aspect of the present invention includes a metal layer, an insulating resin layer overlapping the metal layer, and an adhesive layer overlapping the insulating resin layer and having thermoplastic or thermosetting properties. Equipped with The thickness of the adhesive layer is 3 μm or more and 30 μm or less. The thickness variation of the combined thickness of the metal layer, the insulating resin layer, and the adhesive layer is within ±5 μm based on an average value.

A printed wiring board according to one aspect of the present invention includes an insulating layer made from the insulating resin layer and the adhesive layer in the metal foil-covered resin sheet, and conductor wiring embedded in the insulating layer.

In the method for manufacturing a resin sheet with metal foil according to one embodiment of the present invention, an insulating resin layer is formed from an insulating resin composition on a metal layer, and an adhesive layer is formed from an adhesive resin composition on the insulating resin layer. The volatile component content in at least one of the insulating resin composition and the adhesive resin composition is 30% by mass or more.

According to one aspect of the present invention, there is provided a resin sheet with a metal foil that is unlikely to cause a short circuit when conductor wiring or electronic components are embedded in an adhesive layer, a printed wiring board manufactured using the resin sheet with the metal foil, and a printed wiring board manufactured using the resin sheet with the metal foil. It is possible to provide a method for manufacturing a resin sheet with a laminate.

FIG. 1 is a schematic cross-sectional view of a resin sheet with metal foil according to an embodiment of the present invention. 2A and 2B are schematic cross-sectional views showing the manufacturing process of a printed wiring board according to an embodiment of the present invention.

Embodiments of the present invention will be described below.

As shown in FIG. 1, the metal foil-covered resin sheet 1 according to the present embodiment includes a metal layer 2, an insulating resin layer 3 overlapping the metal layer 2, and a thermoplastic or insulating resin layer 3 overlapping the insulating resin layer 3. The adhesive layer 4 has thermosetting properties. The thickness of the adhesive layer 4 is 3 μm or more and 30 μm or less. The variation in the combined thickness of the metal layer 2, insulating resin layer 3, and adhesive layer 4 with respect to the average value is within ±5 μm.

Therefore, according to the present embodiment, when the printed wiring board 11 is multilayered using the resin sheet 1 with metal foil, it is easy to embed the conductor wiring 7 in the adhesive layer 4. Moreover, the electronic component 8 is also easily embedded in the adhesive layer 4. The electronic component 8 is, for example, a chip component mounted on the conductor wiring 7 or a component such as an inductor element configured as a part of the conductor wiring 7. In this embodiment, part of the inductor element may also be included in the electronic component 8. Furthermore, the insulating resin layer 3 makes it difficult for the conductor wiring 7 or the electronic component 8 embedded in the adhesive layer 4 to reach the metal layer 2 . Furthermore, since the thickness accuracy of the resin sheet 1 with metal foil is high, it is difficult for the thickness of the resin sheet 1 with metal foil to become partially thin, and therefore, the conductor wiring 7 embedded in the adhesive layer 4 or This makes it even more difficult for the electronic component 8 to reach the metal layer 2.

This embodiment will be described in more detail.

The metal layer 2 is made of metal foil such as copper foil, for example. The thickness of the metal layer 2 is preferably 2 μm or more and 20 μm or less. In this case, various circuit forming methods such as a subtractive method and a semi-additive method (SAP) can be easily applied to produce conductor wiring from the metal layer 2.

The insulating resin layer 3 has, for example, thermoplasticity or contains a cured product of a thermosetting resin composition. When the insulating resin layer 3 has thermoplasticity, the adhesive strength between the insulating resin layer 3 and the metal layer 2 is improved. Further, when the insulating resin layer 3 contains a cured product of a thermosetting resin composition, the adhesive force between the insulating resin layer 3 and the adhesive layer 4 is improved.

The insulating resin layer 3 is made of, for example, a resin composition (hereinafter also referred to as an insulating resin composition).

When the insulating resin layer 3 has thermoplasticity, the insulating resin composition is, for example, a thermoplastic resin composition. The thermoplastic resin composition includes at least one thermosetting resin selected from the group consisting of, for example, a liquid crystal polymer resin, a polyimide resin, a polyamideimide resin, a fluororesin, and a polyphenylene ether resin. It is particularly preferable that the thermoplastic resin composition contains at least one of a polyimide resin and a polyamideimide resin. In this case, it is easy to achieve both high levels of insulation and bending resistance of the insulating resin layer 3.

A polyimide resin can be obtained, for example, by preparing a resin liquid containing a polyimide resin as follows. First, a polyamic acid is produced by polycondensation of a tetracarboxylic dianhydride and a diamine component. The tetracarboxylic dianhydride preferably contains 3,3',4,4'-diphenylsulfone tetracarboxylic dianhydride. The diamine component is selected from the group consisting of 2,2-bis[4-(4-aminophenoxy)phenyl]propane, and 4,4'-diaminodiphenyl ether, bis[4-(4-aminophenoxy)phenyl]sulfone. It is preferable to contain at least one component. Subsequently, the polyamic acid is heated in a solvent. The solvent contains at least one component selected from, for example, N-methyl-2-pyrrolidone, methyl ethyl ketone, toluene, dimethylacetamide, dimethylformamide, and methoxypropanol. The heating temperature is, for example, in the range of 60 to 250°C, preferably in the range of 100 to 200°C, and the heating time is, for example, in the range of 0.5 to 50 hours. Thereby, the polyamic acid is imidized by a cyclization reaction, and a polyimide resin is produced. Thereby, a resin liquid containing a polyimide resin is obtained.

When producing the insulating resin layer 3 from a polyimide resin, the insulating resin layer 3 can be produced, for example, by applying a resin liquid containing a polyimide resin onto a metal foil, etc., and then heating and drying it.

The polyamide-imide resin can be obtained, for example, by preparing a resin liquid containing the polyamide-imide resin in the following manner. First, a mixture is prepared by mixing trimellitic anhydride, 4,4'-diisocyanato-3,3'-dimethylbiphenyl, tolylene 2,4-diisocyanate, diazabicycloundecene, and N,N-dimethylacetamide. do. By heating and reacting this mixture, a mixed solution containing polyamideimide is obtained. Subsequently, the mixed liquid is cooled. Furthermore, bismaleimide is added to this mixed solution. Thereby, a resin liquid containing polyamideimide is obtained.

When producing the insulating resin layer 3 from a polyamide-imide resin, the insulating resin layer 3 can be produced, for example, by applying a resin liquid containing the polyamide-imide resin onto a metal foil or the like and then heating and drying it.

When the insulating resin layer 3 contains a cured product of a thermosetting resin composition, the insulating resin composition is, of course, a thermosetting resin composition. The thermosetting resin composition is, for example, an epoxy resin composition. In this case, the insulating resin layer 3 tends to have high insulation properties, and high adhesive strength between the insulating resin layer 3 and the adhesive layer 4 can be obtained. The epoxy resin composition may further contain carbodiimide-modified soluble polyamide. In this case, the insulating resin layer 3 tends to have bending resistance.

Epoxy resins include, for example, a group consisting of glycidyl ether type epoxy resins, glycidyl ester type epoxy resins, glycidyl amine type epoxy resins, oxidized epoxy resins, epoxy resins having a naphthalene skeleton, biphenyl novolac epoxy resins, phosphorus-modified epoxy resins, etc. Contains at least one component selected from.

The epoxy resin composition may further contain a curing agent. The curing agent contains, for example, at least one component selected from the group consisting of polyamines, modified polyamines, acid anhydrides, hydrazine derivatives, polyphenols, and the like. The content of the curing agent is, for example, 10% by mass or more and 45% by mass or less based on the total amount of the epoxy resin, the curing agent, and the carbodiimide-modified soluble polyamide.

Carbodiimide-modified soluble polyamide is obtained by reacting a soluble polyamide and a carbodiimide compound at a reaction temperature of 50 to 250° C. in the presence or absence of a solvent.

Soluble means having solubility in an organic solvent. 1 part by mass or more, preferably 5 parts by mass or more, more preferably 10 parts by mass or more of the soluble polyamide is completely dissolved in 100 parts by mass of the mixture of alcohol and organic solvent such as aromatic and/or ketone solvent. It is possible. Examples of the alcohol in this case include methanol, ethanol, isopropyl alcohol, etc., examples of the aromatic solvent include benzene, toluene, etc., and examples of the ketone solvent include cyclohexanone. , 2-butanone, cyclopentanone and the like. The boiling point of each of these alcohols, aromatic solvents, and ketone solvents is preferably 130°C or lower.

Soluble polyamides are obtained, for example, by solubilizing polyamides. Examples of solubilization methods include a method in which hydrogen atoms in amide bonds of various polyamides are partially substituted with methoxymethyl groups. When a methoxy group is introduced into a polyamide, the hydrogen bonding ability of the amide group is lost, and the crystallinity of the polyamide is inhibited, thereby increasing its solubility in a solvent. Further, examples of the above-mentioned solubilization method include a method of introducing polyether or polyester into the polyamide molecules before solubilization to form a copolymer. Examples of the polyamide before solubilization include nylon 6, nylon 66, nylon 610, nylon 11, nylon 12, and nylon 46.

Specific examples of soluble polyamides include "Zytel 61" (manufactured by DuPont), "Versalon" (manufactured by General Mills), "Amilan CM4000" (manufactured by Toray Industries, Inc.), and "Amilan CM8000" (manufactured by Toray Industries, Inc.). , "PA-100" (manufactured by Fuji Kasei Kogyo Co., Ltd.), "Torezin" (manufactured by Nagase ChemteX Co., Ltd.), and the like.

A carbodiimide compound has one or more carbodiimide groups in its molecule. The carbodiimide compound contains at least one of, for example, a monocarbodiimide compound having only one carbodiimide group in the molecule, and a polycarbodiimide compound having two or more carbodiimide groups in the molecule. Carbodiimide compounds can be synthesized, for example, by decarboxylation condensation reaction of various polyisocyanates at a temperature of about 70° C. or higher without a solvent or in an inert solvent using an organophosphorus compound or an organometallic compound as a catalyst. Can be done.

The monocal -bodyimide compound is, for example, a monocal -bodyimide compound,, for example, a dischicrohexylcyl bogimide, a dizopylcalvyimide, a diocylcalvyimide, a dioxobutyl kalbu -jimide, a jokuchilkalbieimide, T -butyluisopylcalvyimide, diphenilcalvyimide, diphenilcalvyimide Select from a group consisting of Lukal Bajimide and Jaedo -β -Nufflucal Bajimide, etc. contains at least one component that is

Polycarbodiimide compounds can be produced in a variety of ways. The polycarbodiimide compound can be prepared by, for example, a conventional polycarbodiimide manufacturing method (for example, US Pat. No. 2,941,956, J. Org. Chem. 28, 2069-2075 (1963), Chemical Review 1981, Vol. 81 No. 4, p. 619). -621).

Carbodiimide-modified soluble polyamide is produced by reacting the above-mentioned soluble polyamide with a carbodiimide compound in the presence or absence of a solvent, and reacting with reactive functional groups such as carboxyl groups and amino groups possessed by the soluble polyamide, and the carbodiimide compound capable of reacting with these. It is obtained by reacting the carbodiimide group or isocyanate group of .

The method of reacting the soluble polyamide and the carbodiimide compound is not particularly limited, but it can be carried out in the presence or absence of a solvent.

By reacting the soluble polyamide with the carbodiimide compound, the soluble polyamide is modified and becomes a carbodiimide-modified soluble polyamide. As this reaction progresses, the carbodiimide group possessed by the carbodiimide compound decreases, so when comparing the reactant and product by infrared measurement, the peak of the carbodiimide group observed in the reactant decreases in the product. . Furthermore, when performing differential thermal thermogravimetry on the reactants and products, multiple endothermic peaks for the reactants are observed, such as those due to amide resins and carbodiimide resins, but the endothermic peaks for the products are aggregated into one. Ru. From the above, it can be confirmed that the soluble polyamide has been modified.

The content of the carbodiimide-modified soluble polyamide is preferably 20 to 70% by mass based on the total amount of the epoxy resin, curing agent, and carbodiimide-modified soluble polyamide. In this case, the flexibility and chemical resistance of the insulating resin layer 3 can be improved.

The epoxy resin composition may further contain a phenoxy resin, a phosphorus flame retardant, and the like.

The insulating resin composition may contain volatile components. Note that a component that evaporates without forming the insulating resin layer 3 when the insulating resin layer 3 is produced from the insulating resin composition is a volatile component. Volatile components include, for example, solvents. Examples of solvents include methyl ethyl ketone. In this case, it is easy to mold the insulating resin composition into a film shape, and therefore it is easy to form the insulating resin layer 3 from the insulating resin composition with good thickness accuracy. In particular, the content of volatile components is preferably 30% by mass or more based on the entire insulating resin composition. In this case, it is easy to manufacture the insulating resin layer 3 with particularly good thickness accuracy. There is no particular restriction on the upper limit of the content of the volatile component, but in order to efficiently volatilize the volatile component when producing the insulating resin layer 3, it is preferably 50% by mass or less based on the entire insulating resin composition.

The thickness of the insulating resin layer 3 is preferably 2 μm or more and 10 μm or less. By having this thickness of 2 μm or more, the insulating resin layer 3 can make it particularly difficult for the conductor wiring 7 or the electronic component 8 to reach the metal layer 2 . Moreover, since this thickness is 10 μm or less, it is easy to reduce the thickness of the metal foil-covered resin sheet 1 provided with the insulating resin layer 3 and the printed wiring board produced from the metal foil-covered resin sheet 1.

When the insulating resin layer 3 has thermoplasticity, the softening point of the insulating resin layer 3 is preferably higher than the heating temperature of the adhesive layer 4 when manufacturing the printed wiring board 11 using the resin sheet 1 with metal foil. . In this case, since the insulating resin layer 3 is not softened when the adhesive layer 4 is heated, the insulating resin layer 3 makes it particularly difficult for the conductor wiring 7 or the electronic component 8 to reach the metal layer 2. The specific value of the softening point of the insulating resin layer 3 is set depending on the heating temperature, but it is preferably 100° C. or more higher than the heating temperature. The softening point of the insulating resin layer 3 is, for example, 300° C. or more and 330° C. or less. In addition, when measuring the softening point of the insulating resin layer 3, for example, using a rheometer, the viscosity of the insulating resin layer 3 - Obtain the temperature relationship curve. The temperature of the lowest viscosity in this relationship curve is defined as the softening point.

The adhesive layer 4 has thermoplastic or thermosetting properties. The adhesive layer 4 is made of, for example, a resin composition (hereinafter also referred to as an adhesive resin composition).

When the adhesive layer 4 has thermoplasticity, the adhesive resin composition is, for example, a thermoplastic resin composition. The thermoplastic resin composition includes, for example, at least one resin selected from the group consisting of liquid crystal polymer resin, polyimide resin, polyamideimide resin, fluororesin, and polyphenylene ether resin. It is particularly preferable that the thermoplastic resin composition contains at least one of a polyimide resin and a polyamideimide resin. In this case, the surface roughness of the object to be adhered to the adhesive layer 4 does not easily affect the adhesion between the adhesive layer 4 and the object. Adhesion to objects tends to be good. Note that as the polyimide resin and polyamide-imide resin, the polyimide resin and polyamide-imide resin described in the above description of the insulating resin composition can be used.

When the adhesive layer 4 has thermosetting properties, the adhesive resin composition is, for example, a thermosetting resin composition. In this case, the adhesive layer 4 contains, for example, a dried or cured thermosetting resin composition. The thermosetting resin composition contains, for example, an epoxy resin. The thermosetting resin composition may further contain carbodiimide-modified soluble polyamide. In this case, although the adhesive layer 4 has thermosetting properties, the cured product of the adhesive layer 4 tends to have bending resistance.

When the thermosetting resin composition contains an epoxy resin, the composition of the epoxy resin composition when the above-mentioned insulating resin composition is an epoxy resin composition can be adopted as the composition of the thermosetting resin composition.

The adhesive resin composition may contain volatile components. Note that a component that evaporates without forming the adhesive layer 4 when the adhesive layer 4 is produced from the adhesive resin composition is a volatile component. Volatile components include, for example, solvents. Examples of solvents include methyl ethyl ketone. In this case, it is easy to mold the adhesive resin composition into a film shape, and therefore it is easy to form the adhesive layer 4 from the adhesive resin composition with good thickness accuracy. In particular, the content of volatile components is preferably 30% by mass or more based on the entire adhesive resin composition. In this case, it is easy to manufacture the adhesive layer 4 with particularly good thickness accuracy. Although there is no particular restriction on the upper limit of the content of volatile components, it is preferably 50% by mass or less in order to volatilize volatile components efficiently.

The thickness of the adhesive layer 4 is 3 μm or more and 30 μm or less, as described above. When this thickness is 3 μm or more, it is easy to embed the conductive wiring 7 or the electronic component 8 in the adhesive layer 4. Moreover, since the thickness is 30 μm or less, the conductor wiring 7 or the electronic component 8 can be easily embedded in the adhesive layer 4, and the resin sheet 1 with metal foil provided with the adhesive layer 4 can be manufactured from the resin sheet 1 with metal foil. It is possible to prevent the thickness of printed wiring boards, etc., from becoming excessively large. The thickness of the adhesive layer 4 is more preferably 3 μm or more and 15 μm or less.

In both the case where the insulating resin layer 3 has thermoplasticity and the case where the insulating resin layer 3 contains a cured product of a thermosetting resin composition, the adhesive layer 4 is either thermoplastic or thermosetting. May have.

When the insulating resin layer 3 has thermoplasticity and the adhesive layer 4 has thermoplasticity, the softening point of the adhesive layer 4 is preferably lower than that of the insulating resin layer 3. In this case, even if the heating temperature of the adhesive layer 4 when manufacturing the printed wiring board 11 using the resin sheet 1 with metal foil is lower than the softening point of the insulating resin layer 3, the adhesive layer 4 cannot be softened. It is easy to embed the conductor wiring 7 or the electronic component 8 in the adhesive layer 4. In this case, since the insulating resin layer 3 is not softened, the insulating resin layer 3 makes it particularly difficult for the conductor wiring 7 or the electronic component 8 to reach the metal layer 2, as described above. It is preferable that the difference between the softening point of the adhesive layer 4 and the softening point of the insulating resin layer 3 is 100° C. or more. It is also preferable that this difference is 200°C or less. It is more preferable that this difference is 100°C or more and 150°C or less.

When the insulating resin layer 3 has thermoplasticity and the adhesive layer 4 has thermosetting property, the curing start temperature of the adhesive layer 4 is preferably lower than the softening point of the insulating resin layer 3. In this case, even if the heating temperature of the adhesive layer 4 when manufacturing the printed wiring board 11 using the resin sheet 1 with metal foil is lower than the softening point of the insulating resin layer 3, the adhesive layer 4 cannot be softened. It is easy to harden the adhesive layer 4 after embedding the conductor wiring 7 or the electronic component 8 in the adhesive layer 4. In this case, since the insulating resin layer 3 is not softened, the insulating resin layer 3 makes it particularly difficult for the conductor wiring 7 or the electronic component 8 to reach the metal layer 2, as described above. The curing start temperature of the adhesive layer 4 is measured by thermomechanical analysis (TMA method). Specifically, the adhesive layer 4 was measured by the TMA method under conditions of a temperature range of 20 to 180°C and a temperature increase rate of 1.5°C/min, and the temperature corresponding to the peak top observed in the obtained TMA curve was determined. This is the curing start temperature. It is preferable that the difference between the hardening start temperature of the adhesive layer 4 and the softening point of the insulating resin layer 3 is 100° C. or more. It is also preferable that this difference is 200°C or less. It is more preferable that this difference is 100°C or more and 150°C or less.

When the insulating resin layer 3 contains a cured product of a thermosetting resin composition and the adhesive layer 4 has thermoplasticity, the softening point of the adhesive layer 4 is equal to the glass transition temperature and decomposition start temperature of the insulating resin layer 3. It is preferable that it is lower than either. In this case, even if the heating temperature of the adhesive layer 4 when manufacturing the printed wiring board 11 using the resin sheet 1 with metal foil is lower than the glass transition temperature and decomposition start temperature of the insulating resin layer 3, the adhesive layer The conductive wiring 7 or the electronic component 8 can be easily embedded in the adhesive layer 4 by softening the adhesive layer 4. In this case, since the insulating resin layer 3 does not reach the glass transition temperature and does not decompose, the insulating resin layer 3 can make it particularly difficult for the conductor wiring 7 or the electronic component 8 to reach the metal layer 2. The difference between the softening point of the adhesive layer 4 and the glass transition point of the insulating resin layer 3 is preferably 100° C. or more. It is also preferable that this difference is 200°C or less. It is more preferable that this difference is 100°C or more and 150°C or less. The difference between the softening point of the adhesive layer 4 and the decomposition start temperature of the insulating resin layer 3 is preferably 200° C. or more. It is also preferable that this difference is 300°C or less. It is more preferable that this difference is 200°C or more and 250°C or less. The insulating resin layer 3 is measured by the TMA method under conditions of a temperature range of 20 to 180°C and a heating rate of 1.5°C/min, and the temperature at which a sudden change begins to occur in the obtained TMA curve is defined as the glass transition point. shall be. Further, the insulating resin layer 3 is measured by laser Raman spectroscopy to examine changes in the Raman spectrum in response to temperature changes, and the temperature at which the waveform peak of the Raman spectrum changes is determined as the decomposition start temperature.

When the insulating resin layer 3 contains a cured product of a thermosetting resin composition and the adhesive layer 4 has thermosetting properties, the curing start temperature of the adhesive layer 4 is determined by the glass transition temperature and decomposition temperature of the insulating resin layer 3. Preferably, the temperature is lower than either of the starting temperatures. In this case, even if the heating temperature of the adhesive layer 4 when manufacturing the printed wiring board 11 using the resin sheet 1 with metal foil is lower than both the glass transition temperature and the decomposition start temperature of the insulating resin layer 3, After softening the adhesive layer 4 and embedding the conductive wiring 7 or the electronic component 8 in the adhesive layer 4, it is easy to harden the adhesive layer 4. In this case, since the insulating resin layer 3 does not reach the glass transition temperature and does not decompose, the insulating resin layer 3 can make it particularly difficult for the conductor wiring 7 or the electronic component 8 to reach the metal layer 2. The difference between the curing start temperature of the adhesive layer 4 and the glass transition point of the insulating resin layer 3 is preferably 100° C. or more. It is also preferable that this difference is 200°C or less. It is more preferable that this difference is 100°C or more and 150°C or less. The difference between the curing start temperature of the adhesive layer 4 and the decomposition start temperature of the insulating resin layer 3 is preferably 200° C. or more. It is also preferable that this difference is 300°C or less. It is more preferable that this difference is 200°C or more and 250°C or less.

Regardless of whether the adhesive layer 4 is thermoplastic or thermosetting, the minimum melt viscosity of the adhesive layer 4 is preferably less than 10 ⁵ Pa·s. In this case, by heating the adhesive layer 4 when manufacturing the printed wiring board 11 using the resin sheet 1 with metal foil, good fluidity can be imparted to the adhesive layer 4. The electronic component 8 can be particularly easily embedded. This minimum melt viscosity is more preferably 1.0×10 ⁴ Pa·s or more and less than 1.0×10 ⁵ Pa·s. In addition, when measuring the minimum melt viscosity, for example, using a rheometer, the viscosity-temperature relationship curve of the adhesive layer 4 is measured under the conditions of a temperature increase rate of 1.5 °C/min, a temperature range of 20 to 180 °C, and a frequency of 5 Hz. get. The minimum viscosity in this relationship curve is defined as the minimum melt viscosity.

As described above, the thickness variation based on the average value of the combined thicknesses of the metal layer 2, insulating resin layer 3, and adhesive layer 4 is within ±5 μm. That is, the maximum value of the combined thickness of the metal layer 2, the insulating resin layer 3, and the adhesive layer 4 is less than or equal to a value that is 5 μm larger than the average value of this thickness, and the total thickness of the metal layer 2, the insulating resin layer 3, and the adhesive layer 4 The minimum value of the combined thickness is at least 5 μm smaller than the average value of the thickness. This variation is confirmed by the following method. Five measurement positions arranged in one direction are set on the resin sheet 1 with metal foil, and the combined thickness of the metal layer 2, insulating resin layer 3, and adhesive layer 4 is measured at each measurement position using a digital micrometer. do. The average value of the five measured values thus obtained is calculated. When the maximum value of the measured thickness is equal to or less than the average value +5 μm, and the minimum value of the measured thickness value is equal to or greater than the average value −5 μm, the variation with respect to the average value of the thickness is within ±5 μm. When the variation in thickness with respect to the average value is within ±5 μm, the resin sheet 1 with metal foil is less likely to have areas where the thickness is partially reduced and areas where the thickness is partially increased. Therefore, if the thickness of the conductor wiring 7 or the electronic component 8 and the combined thickness of the metal layer 2, insulating resin layer 3, and adhesive layer 4 are adjusted in advance, the conductor wiring 7 or the electronic component 8 can be easily embedded, and the conductor wiring 7 or the electronic component 8 can be made difficult to reach the metal layer 2. The variation based on the average value of the thickness is preferably within ±4, and even more preferably within ±3. Ideally, this variation is preferably zero.

A specific example of the method for manufacturing the metal foil-covered resin sheet 1 will be described.

In this method, first, the insulating resin layer 3 is formed on the metal layer 2 from an insulating resin composition. An adhesive layer 4 is produced on this insulating resin layer 3 from an adhesive resin composition.

In this method, the content of volatile components in at least one of the insulating resin composition and the adhesive resin composition is preferably 30% by mass or more. In this case, the thickness accuracy of the resin sheet 1 with metal foil tends to be particularly high, and the thickness variation of the combined thickness of the metal layer 2, insulating resin layer 3, and adhesive layer 4 based on the average value is within ±5 μm. It is easy to accomplish something.

This method will be explained in more detail.

First, a metal foil such as copper foil, which is the material of the metal layer 2, an insulating resin composition, which is the material of the insulating layer 5, and an adhesive resin composition, which is the material of the adhesive layer 4, are prepared.

An insulating resin composition is applied onto the surface of the metal foil. It is preferable to apply the insulating resin composition using a comma coater. In this case, by adjusting the dimension of the gap between the applicator roll and the backup roll in the comma coater, it is easy to precisely control the thickness of the insulating resin composition on the metal foil.

Subsequently, the insulating resin composition on the metal foil is heated. Thereby, when the insulating resin composition is a thermoplastic resin composition, the thermoplastic insulating resin layer 3 is produced by volatilizing volatile components such as a solvent from the thermoplastic resin composition. In addition, when the insulating resin composition is a thermosetting resin composition, by volatilizing volatile components such as a solvent from the thermosetting resin composition and further thermosetting the thermosetting resin composition, An insulating resin layer 3 containing a cured product of a thermosetting resin composition is produced. The conditions for heating the insulating resin composition are appropriately set depending on the composition of the insulating resin composition.

When producing the insulating resin layer 3 in this way, if the content of volatile components in the insulating resin composition is 30% by mass or more, the insulating resin composition on the metal foil is It is easier to control the thickness of the resin composition. Furthermore, even if there are variations in the dimensions of the gap between the applicator roll and the backup roll in the comma coater, as long as the volatile component content is 30% by mass or more, the insulating layer made from the insulating resin composition Variations in the thickness of 5 are less likely to occur. Therefore, it is particularly easy to improve the thickness accuracy of the resin sheet 1 with metal foil.

Subsequently, an adhesive resin composition is applied onto the insulating resin layer 3. It is preferable to apply the adhesive resin composition with a comma coater. In this case, the thickness of the adhesive resin composition on the insulating resin layer 3 can be easily controlled precisely by adjusting the dimension of the gap between the applicator roll and the backup roll in the comma coater.

Subsequently, the adhesive resin composition on the metal foil is heated. Thereby, when the adhesive resin composition is a thermoplastic resin composition, the thermoplastic adhesive layer 4 is produced by volatilizing volatile components such as a solvent from the thermoplastic resin composition. In addition, when the adhesive resin composition is a thermosetting resin composition, volatile components such as solvents are volatilized from the thermosetting resin composition, or the thermosetting resin composition is further semi-cured. , an adhesive layer 4 containing a dried or semi-cured thermosetting resin composition is prepared. The conditions for heating the adhesive resin composition are appropriately set depending on the composition of the adhesive resin composition.

In producing the adhesive layer 4 in this way, if the volatile component content of the adhesive resin composition is 30% by mass or more, the adhesive resin composition may be applied to the insulating resin layer 3 when the adhesive resin composition is applied on the insulating resin layer 3. It is easier to control the thickness of the upper adhesive resin composition. Furthermore, even if there are variations in the dimensions of the gap between the applicator roll and the backup roll in the comma coater, as long as the volatile component content is 30% by mass or more, the adhesive layer produced from the adhesive resin composition can be used. Variations in the thickness of 4 are less likely to occur. Therefore, it is particularly easy to improve the thickness accuracy of the resin sheet 1 with metal foil.

In the above, at the time when the insulating resin composition on the metal foil is heated to produce the insulating resin layer 3, the insulating resin layer 3 may not be completely cured but may be in a semi-cured state, for example. In this case, when heating the adhesive resin composition on the insulating resin layer 3, the insulating resin layer 3 may also be heated to further advance the curing reaction of the insulating resin layer 3.

The method for manufacturing the resin sheet 1 with metal foil is not limited to the above method. For example, when the insulating resin composition is a thermosetting resin composition and the adhesive resin composition is a thermosetting resin composition, the resin sheet 1 with metal foil can also be manufactured as follows.

First, an insulating resin composition is applied onto the surface of metal foil. The method may be the same as described above.

Subsequently, an adhesive resin composition is applied onto the insulating resin composition without heating the insulating resin composition on the metal foil. The method may be the same as described above.

Subsequently, the insulating resin composition and adhesive resin composition on the metal foil are heated simultaneously. Thereby, the insulating resin composition is thermally cured, and the adhesive resin composition is dried or further semi-cured. Thereby, the insulating resin layer 3 containing the cured product of the insulating resin composition and the adhesive layer 4 containing the dried or semi-cured product of the adhesive resin composition are produced, and the resin sheet 1 with metal foil is obtained.

When manufacturing the resin sheet 1 with metal foil in this way, when the insulating resin composition and the adhesive resin composition are heated under the same conditions, the curing reaction of the insulating resin composition is higher than that of the adhesive resin composition. It is preferable that the reaction proceeds more easily than the curing reaction. For example, when the gel time at 180° C. of the insulating resin composition is compared with the gel time at 180° C. of the adhesive resin composition, it is preferable that the gel time of the insulating resin composition is shorter by 30 seconds or more. For example, it is preferable that the gel time of the insulating resin composition is 60 seconds, and the gel time of the adhesive resin composition is 180 seconds. In this case, by heating the insulating resin composition and the adhesive resin composition simultaneously, the insulating resin layer 3 containing the cured product of the insulating resin composition and the adhesive layer containing the dried or semi-cured product of the adhesive resin composition can be formed. 4 is particularly easy to produce. Note that gel time is the time required from the start of the test until the viscosity reaches 500,000 mPa·s when a test is conducted to measure the viscosity using a gel time tester while maintaining each composition at 180°C. In this case, even if the insulating resin composition and the adhesive resin composition on the metal foil are heated simultaneously, the insulating resin layer 3 containing the cured product of the insulating resin composition and the dried or semi-cured product of the adhesive resin composition An adhesive layer 4 containing the following can be produced.

The ease with which the curing reaction of the insulating resin composition and the adhesive resin composition progresses depends, for example, on the effectiveness of at least one of the curing agent and the curing accelerator in each of the insulating resin composition and the adhesive resin composition. It can be controlled by changing the type, adjusting the amount of at least one of the curing agent and curing accelerator relative to the thermosetting resin. For example, the types of components contained in the insulating resin composition and the types of components contained in the adhesive resin composition are the same, and the amount of at least one of the curing agent and curing accelerator for the thermosetting resin in the insulating resin composition is If the amount of at least one of the curing agent and curing accelerator for the thermosetting resin in the adhesive resin composition is larger, the curing reaction of the insulating resin composition progresses faster than the curing reaction of the adhesive resin composition. It can become easier.

A printed wiring board 11 manufactured using the resin sheet 1 with metal foil will be explained.

As shown in FIG. 2B, the printed wiring board 11 includes an insulating layer 5 made of, for example, an insulating resin layer 3 and an adhesive layer 4 in a resin sheet 1 with metal foil, and conductor wiring 7 embedded in the insulating layer 5. Equipped with. Printed wiring board 11 may further include electronic components 8 embedded in insulating layer 5 .

A method for manufacturing such a printed wiring board 11 will be specifically explained.

First, a resin sheet 1 with metal foil and a core material 9 are prepared.

The core material 9 includes a base material 6 having electrical insulation properties and conductive wiring 7 on the base material 6. In the example shown in FIG. 2A, the conductor wiring 7 includes, as the electronic component 8, a spiral wiring (hereinafter referred to as a spiral portion 71) that constitutes a part of an inductor element. In the example shown in FIG. 2A, the line width in the spiral portion 71 is larger than the thickness of the spiral portion 71.

This core material 9 and the resin sheet 1 with metal foil are stacked so that the conductor wiring 7 in the core material 9 and the adhesive layer 4 in the resin sheet 1 with metal foil are opposed to form a laminate. Heat press.

When the adhesive layer 4 has thermoplasticity, when the laminate is hot-pressed as described above, the adhesive layer 4 softens and flows, and the conductor wiring 7 is embedded in the adhesive layer 4 as shown in FIG. 2A. As a result, the spiral portion 71, which is the electronic component 8, is also embedded in the adhesive layer 4. Subsequently, the adhesive layer 4 is solidified. As a result, an insulating layer 5 made of a solidified product of the insulating resin layer 3 and the adhesive layer 4 is produced, and the conductor wiring 7 and the spiral portion 71 are embedded in this insulating layer 5.

In addition, when the adhesive layer 4 has thermosetting properties, when the laminate is hot-pressed as described above, the adhesive layer 4 first softens and flows, so that the conductor wiring 7 is embedded in the adhesive layer 4. Accordingly, the spiral portion 71 which is the electronic component 8 is also embedded in the adhesive layer 4. Subsequently, the adhesive layer 4 is thermally cured. As a result, an insulating layer 5 made of the cured product of the insulating resin layer 3 and the adhesive layer 4 is produced, and the conductor wiring 7 and the spiral portion 71 are embedded in this insulating layer 5.

When the conductor wiring 7 and the spiral part 71 are embedded in the adhesive layer 4 in this way, the conductor wiring 7 and the spiral part 71 are easily embedded in the adhesive layer 4, and the conductor wiring 7 and the spiral part 71 are easily embedded in the adhesive layer 4 for the reasons already explained. It is difficult to reach the metal layer 2. Therefore, a short circuit between each of the conductor wiring 7 and the spiral portion 71 and the metal layer 2 is less likely to occur.

Subsequently, if necessary, as shown in FIG. 2B, a conductor wiring 10 (hereinafter referred to as second conductor wiring 10) is formed from the metal layer 2 originating from the metal foil-covered resin sheet 1 to the core material 9 by photolithography or the like. The resulting conductor wiring 7 is referred to as a first conductor wiring 7). The second conductor wiring 10 may include, as the electronic component 8, a spiral wiring (hereinafter referred to as a spiral portion 101) that constitutes a part of an inductor element. That is, the spiral portion 71 in the first conductor wiring 7 and the spiral portion 101 in the second conductor wiring 10 may each constitute a part of the same inductor element. In this case, the spiral portion 71 of the first conductor wiring 7 and the spiral portion 101 of the second conductor wiring 10 are electrically connected by a via or the like.

In this way, a printed wiring board 11 is obtained as the electronic component 8 including the spiral portions 71 and 101 and the inductor element constituted by the spiral portions 71 and 101.

Further, a printed wiring board 11 manufactured using the resin sheet 1 with metal foil is used as a core material 9, and the insulating layer 5 and conductor wiring 7 are formed using the resin sheet 1 with metal foil on this core material 9 by the above method. By stacking them, a printed wiring board 11 with even more layers can be obtained. Further, by repeatedly stacking the insulating layer 5 and the conductive wiring 7 on the core material 9 using the resin sheet 1 with metal foil, a printed wiring board 11 with even more layers can be obtained.

Note that in the above description, the core material 9 includes the electronic component 8 configured as a part of the conductor wiring 7, but the core material 9 includes the electronic component 8 such as a semiconductor device or a chip resistor mounted on the conductor wiring 7 You may prepare. Also in this case, in this embodiment, the electronic component 8 is easily embedded in the adhesive layer 4 during manufacturing of the printed wiring board 11, and the electronic component 8 is difficult to reach the metal layer 2.

1. Preparation of Resin Sheet with Metal Foil Copper foil having the thickness shown in Table 1 was prepared as the metal layer 2. The copper foil in Examples 1 to 5 and Comparative Examples 1 to 2 is product number F2WS manufactured by Furukawa Electric Co., Ltd., the copper foil in Example 6 is product number SV manufactured by Fukuda Kinzoku Co., Ltd., and the copper foil in Example 7 is is product number MT18Ex manufactured by Mitsui Kinzoku Co., Ltd.

In addition, an insulating resin composition was prepared by mixing the components shown in the raw material composition column of the insulating resin layer 3 shown in Table 1, and the components shown in the raw material composition column of the adhesive layer 4 in Table 1 were mixed, An adhesive resin composition was prepared.

The details of the components shown in Table 1 are as follows.
- Polyamide resin: carbodiimide-modified soluble polyamide, manufactured by Nisshinbo Chemical Co., Ltd., product number AC-07-M14.
- Epoxy resin: manufactured by Nippon Kayaku Co., Ltd., product number NC-3000H.
・Polyamideimide: Manufactured by Toyobo Co., Ltd., product number HR-46NN.
・MEK: Methyl ethyl ketone manufactured by Tokosansha.
・2E4MZ: Manufactured by Shikoku Kasei Co., Ltd., 2-ethyl-4-methylimidazole.

The insulating resin layer 3 was prepared by applying the insulating resin composition to the surface of the metal layer 2 using a comma coater and then heating the insulating resin composition. The manufacturing conditions for the insulating resin layer 3 are shown in the column of manufacturing conditions for the insulating resin layer 3 in Table 1. The coating gap in this column is the gap between the applicator roll and the backup roll in the comma coater, and the heating temperature and heating time are the conditions for heating the insulating resin composition. In addition, in the case of Example 2, the insulating resin composition was not heated. As a result, a semi-finished product including the metal layer 2 and the insulating resin layer 3 was obtained.

Subsequently, an adhesive resin composition is applied onto the insulating resin layer 3 (on the insulating resin composition in the case of Example 2) using a comma coater, and then the adhesive resin composition is heated to form the adhesive layer 4. Created. The column of adhesive resin layer manufacturing conditions in Table 1 shows the manufacturing conditions of the adhesive resin layer. The coating gap in this column is the gap between the applicator roll and the backup roll in the comma coater, and the heating temperature and heating time are the conditions for heating the adhesive resin composition. Moreover, in the case of Example 2, the insulating resin layer 3 and the adhesive resin layer were produced by heating the insulating resin composition and the adhesive resin composition simultaneously. As a result, a metal foil-covered resin sheet 1, which is a product including a metal layer 2, an insulating resin layer 3, and an adhesive layer 4, was produced.

2. Thickness measurement results The thickness of the insulating resin layer 3, the thickness of the adhesive layer 4, the thickness of the semi-finished product, and the thickness of the product (resin sheet with metal foil 1) were measured.

The thickness of the insulating resin layer 3 is the value obtained by subtracting the thickness of the metal layer from the average thickness of the semi-finished product measured by the method described below.

The thickness of the adhesive layer 4 is the value obtained by subtracting the thickness of the semi-finished product measured by the method described below from the average thickness of the product measured by the method described below.

In measuring the thickness of the semi-finished product, five thickness measurement positions were set in one direction on the semi-finished product, and the thickness of the semi-finished product was measured at each measurement position using a digital micrometer. The average value of the five measured values thus obtained is shown in Table 1 as the average thickness. Further, Table 1 shows the variations in the measured values with respect to the average thickness as thickness variations.

To measure the thickness of the product, five thickness measurement positions were set up in one direction on the product, and the thickness of the product was measured at each measurement position using a digital micrometer. The average value of the five measured values thus obtained is shown in Table 1 as the average thickness. Further, Table 1 shows the variations in the measured values with respect to the average thickness as thickness variations.

According to the results shown in Table 1 below, in Examples 1 to 7 in which the volatile component content of at least one of the insulating resin composition and the adhesive resin composition was 30% by mass or more, the product thickness variation was ±5 μm. I was able to achieve within. In particular, it was confirmed that the thickness variations were particularly small in Examples 1 and 2 in which the content of volatile components in both the insulating resin composition and the adhesive resin composition was 30% by mass or more.

3. Physical property measurement results Regarding the insulating resin layer, the softening point, glass transition temperature, decomposition start temperature, and gel time of the insulating resin composition were measured by the methods described above.

Regarding the adhesive layer, the softening point, minimum melt viscosity, gel time of the adhesive resin composition, and curing start temperature were measured by the methods described above.

4. Detailed Evaluation of Volatile Component Content In order to specifically investigate the relationship between volatile component content and thickness accuracy, the following test was conducted.

In Example 2, the content of the solvent in the insulating resin composition was changed to create composition A1 with a volatile component content of 25% by mass, composition A2 with a volatile component content of 30% by mass, and A composition A3 was prepared with a volatile component content of 35% by weight.

Further, in Example 2, the content of the solvent in the adhesive resin composition was changed to create a composition B1 with a volatile component content of 25% by mass and a composition with a volatile component content of 30% by mass. B2 and a composition B3 with a volatile component content of 35% by weight were prepared.

Composition A1, composition A2, and composition A3 were each applied to the surface of metal layer 2 using a comma coater. At this time, the dimension of the center part of the gap between the applicator roll and the backup roll in the comma coater and the variation in the dimension of the center part are as shown in the gap dimension column of Table 2. Subsequently, the insulating resin layer 3 was produced by heating each composition at 300° C. for 1 minute. Five thickness measurement positions arranged in one direction were set on this insulating resin layer 3, and the combined thickness of the metal layer 2 and the insulating resin layer 3 was measured at each measurement position using a digital micrometer. Five measured values of the thickness of the insulating resin layer 3 were obtained by subtracting the thickness of the metal layer 2 from each of the five measured values thus obtained. Table 2 shows the average value of the measured thickness of the insulating resin layer 3 and the variation of the measured value with respect to the average value.

Furthermore, each of composition B1, composition B2, and composition B3 was applied to the surface of metal layer 2 using a comma coater. At this time, the dimension of the center part of the gap between the applicator roll and the backup roll in the comma coater and the variation in the dimension of the center part are as shown in the gap dimension column of Table 2. Subsequently, adhesive layer 4 was produced by heating each composition at 180° C. for 1 minute. Five thickness measurement positions arranged in one direction were set on this adhesive layer 4, and the combined thickness of the metal layer 2 and adhesive layer 4 was measured at each measurement position using a digital micrometer. By subtracting the thickness of the metal layer 2 from each of the five measured values thus obtained, five measured values of the thickness of the adhesive layer 4 were obtained. Table 2 shows the average value of the measured thickness of the adhesive layer 4 and the variation of the measured value with respect to the average value.

As shown in the results, in the case of composition A1 and composition B1 in which the volatile component content was more than 30% by mass, the variation in the thickness of the produced layer was comparable to the variation in the gap size. On the other hand, in the case of compositions A2 and B2 in which the volatile component content is 30% by mass, the variation in the thickness of the produced layer is smaller than the variation in the gap dimension, and the volatile component content is In the case of compositions A3 and B3 containing 35% by mass, the variations in the thickness of the produced layers were further reduced.

5. Regarding embedding of conductor wiring As described above, in Example 1-7, it was possible to achieve a variation in product thickness (the combined thickness of the metal layer, insulating resin layer, and adhesive layer) of ±5 μm or less. Considering the variation in the combined thickness of the metal layer and the insulating resin layer, it can be determined that in Example 1-7, the variation in the thickness of the adhesive layer is within ±1.5 μm to within ±2.5 μm. If the variation in the thickness of the adhesive layer is small in this way, when embedding conductive wiring or electronic components in the adhesive layer, the overall thickness of the adhesive layer (average thickness ) does not need to be increased. Therefore, the thickness of a printed wiring board or the like made from a resin sheet with metal foil can be reduced. That is, the overall thickness of the insulating layer can be reduced while embedding conductor wiring or electronic components in the insulating layer made from the insulating resin layer and the adhesive layer of the resin sheet with metal foil.

Claims (7)

a metal layer;
an insulating resin layer overlapping the metal layer;
and a thermoplastic or thermosetting adhesive layer overlapping the insulating resin layer,
The thickness of the adhesive layer is 3 μm or more and 30 μm or less,
The thickness variation of the combined thickness of the metal layer, the insulating resin layer, and the adhesive layer is within ±5 μm based on an average value,
The insulating resin layer includes a cured product of a thermosetting resin composition.
Resin sheet with metal foil. a metal layer;
an insulating resin layer overlapping the metal layer;
an adhesive layer overlapping the insulating resin layer,
The thickness of the adhesive layer is 3 μm or more and 30 μm or less,
The thickness variation of the combined thickness of the metal layer, the insulating resin layer, and the adhesive layer is within ±5 μm based on an average value,
The insulating resin layer has thermoplasticity,
The adhesive layer has thermoplasticity, and the softening point of the adhesive layer is lower than the softening point of the insulating resin layer.
Resin sheet with metal foil. The thickness of the metal layer is 2 μm or more and 20 μm or less,
The resin sheet with metal foil according to claim 1 or 2. The thickness of the insulating resin layer is 2 μm or more and 10 μm or less,
The resin sheet with metal foil according to any one of claims 1 to 3. The minimum melt viscosity of the adhesive layer is 10 ^Five less than Pa・s,
The resin sheet with metal foil according to any one of claims 1 to 4. An insulating layer made from the insulating resin layer and the adhesive layer in the resin sheet with metal foil according to any one of claims 1 to 5,
and a conductor wiring embedded in the insulating layer.
printed wiring board. A method for manufacturing a resin sheet with metal foil according to any one of claims 1 to 5,
producing the insulating resin layer from an insulating resin composition on the metal layer,
producing the adhesive layer from an adhesive resin composition on the insulating resin layer;
The volatile component content in at least one of the insulating resin composition and the adhesive resin composition is 30% by mass or more,
A method for manufacturing a resin sheet with metal foil.

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