JP6811400B2 - Circuit board manufacturing method - Google Patents

Description

The present invention relates to a method for manufacturing a circuit board.

With the pursuit of miniaturization, multi-functionality, and high-speed communication of electronic devices, higher density and excellent high-frequency characteristics of circuit boards used in electronic devices are required.

In order to meet the demand for high density, a multilayer printed wiring board in which a prepreg and a copper foil are laminated on the upper and lower surfaces of a core substrate in which copper foils on the upper and lower surfaces of a double-sided copper-clad laminate in a desired circuit pattern is used is used. ing. Such a multilayer printed wiring board is manufactured by a batch laminated press method in which a core substrate, a prepreg, and a copper foil are laminated and integrated in a single process (Patent Document 1).

On the other hand, as a metal-clad laminate having excellent high-frequency characteristics, Patent Document 2 states that an inner core layer made of a thermoplastic resin, a thermosetting resin or a thermosetting resin impregnated base material layer as a surface layer, and an outermost layer. A double-sided metal-clad laminate formed by arranging and integrally molding a metal foil is described.

JP-A-2003-347740 Japanese Unexamined Patent Publication No. 4-291782

A multilayer circuit obtained by a batch lamination press method using a substrate formed by etching a metal foil of a double-sided metal-clad laminate having an insulating layer containing a thermoplastic resin as described in Patent Document 2 as a core substrate. The substrate is said to be superior in high frequency characteristics to a multilayer circuit board using a core substrate having an insulating layer made of a cured product of a thermosetting resin.

However, a multilayer circuit board using a core substrate having an insulating layer containing a thermoplastic resin is collectively laminated with the positional accuracy of the circuit patterns on both sides of the core substrate in the XY plane direction perpendicular to the thickness direction (Z direction). There was a problem that there was a risk of deviation in the process of press molding. Therefore, a connection failure may occur when the circuits of each layer are interconnected with vias or the like.

This phenomenon will be described with reference to FIG. For each reference numeral in FIG. 2, 100 is a multilayer circuit board, 111 is an insulating layer containing a thermoplastic resin, 112 is a first circuit having a predetermined pattern, 113 is a second circuit having a predetermined pattern, and 110 is an insulating layer 111. A core substrate having a first circuit 112 and a second circuit 113, 120 is a copper foil, 130 is a prepreg containing a thermosetting resin, and 130a is a cured product (insulating layer) of the prepreg.

As shown in FIG. 2A, the prepreg 130 and the copper foil 120 are laminated on the upper and lower surfaces of the core substrate 110 in this order, arranged between the hot plates, and heat-press molded by a heat press. These are laminated and integrated.

At this time, as shown in FIG. 2A, the insulating layer 111 is heat-press molded while being sandwiched between the prepregs 130 and 130, but the thermoplastic resin has a low elastic modulus and the elastic modulus is further lowered at a high temperature. Since it has a property of being easily softened, the insulating layer 111 is easily deformed. At the same time, the thermosetting resins of the prepregs 130 and 130 arranged on both sides of the core substrate 110 are once melted in the heating process and flow from the central portion to the peripheral portion while filling the gaps between the circuits. The stress associated with the flow acts on the first circuit 112 and the second circuit 113 in the XY plane direction. At this time, since the thermoplastic resin of the insulating layer 111 is softened and the bearing capacity for the first circuit 112 and the second circuit 113 is reduced, the insulating layer 111 is deformed by the stress due to the resin flow and the position of the circuit is changed. Is thought to move. Further, in this state, when the prepreg 130 is further cured and solidified, as shown in FIG. 2B, in the obtained multilayer circuit board 100, the first circuit 112 and the second circuit 113 on the front and back of the core substrate 110 It is considered that this will result in a misalignment of. This phenomenon also occurs when a prepreg in which a fiber base material is impregnated with a thermoplastic resin is used instead of the prepreg 130 having a thermosetting resin, or when a resin adhesive sheet containing no fiber base material is used. It is thought that it can happen. Since heat and pressure molding is not usually performed at a high temperature that makes it difficult to maintain the shape of the insulating layer 111 of the core substrate 110, this positional deviation is not necessarily large. However, in recent years, in the multilayer printed wiring board, the circuit pattern has been made finer, and this problem cannot be ignored in order to secure the connection reliability between the circuits.

The present invention has been made in view of the above points, and an object of the present invention is to provide a method for manufacturing a circuit board having excellent high frequency characteristics and good position accuracy of a circuit pattern.

The method for manufacturing a circuit board according to the present invention includes an insulating layer containing a thermoplastic resin, a first circuit having a predetermined pattern formed on one surface of the insulating layer on the first surface side, and a second surface side. In the step of preparing a core substrate having a planar metal layer bonded to another surface of the insulating layer, and a softening point on the first surface of the core substrate rather than a softening point of the thermoplastic resin. Obtained in the first molding step of arranging the first adhesive layer containing a low resin component and the first metal foil in this order and laminating and integrating them by heat and pressure molding, and the first molding step. In the laminated body, the metal layer is patterned to form a second circuit on the second surface of the core substrate, and then on the second surface of the core substrate, from the softening point of the thermoplastic resin. Also includes a second molding step in which a second adhesive layer containing a resin component having a low softening point and a second metal foil are arranged in this order, and these are laminated and integrated by heat and pressure molding. The first metal foil covers the entire first surface of the core substrate via the first adhesive layer.

According to the present invention, it is possible to manufacture a circuit board having excellent high frequency characteristics and good position accuracy of a circuit pattern. That is, in the first molding step, since the second surface side of the core substrate is supported by the flat metal layer, the thermoplastic resin is softened by lowering the elastic modulus during heat and pressure molding. However, the deformation of the insulating layer is suppressed, and the positional deviation of the first circuit is also suppressed. Further, in the second molding step, since the first surface side of the core substrate is supported by the cured layer of the first adhesive layer, the thermoplastic resin has a low elastic modulus during heat and pressure molding. Even if it is softened and softened, the deformation of the insulating layer is suppressed, and the positional deviation of the second circuit is also suppressed. As described above, according to the present invention, the first metal foil and the second metal foil are molded one side at a time with respect to the insulating layer even when a core substrate containing a thermoplastic resin having excellent high frequency characteristics is used. Therefore, the positional deviation between the first circuit and the second circuit is unlikely to occur on the front and back of the insulating layer. Therefore, the position accuracy of the first circuit and the second circuit in the XY plane direction perpendicular to the thickness direction (Z direction) of the core substrate is high, and the circuit board has high electrical reliability. Can be done.

1A to 1E are explanatory views for explaining a method of manufacturing a circuit board according to an embodiment of the present invention. 2A and 2B are explanatory views for explaining a heating and pressurizing step of a conventional method for manufacturing a circuit board using a batch laminated press method.

Hereinafter, modes for carrying out the present invention will be described.

[One Embodiment of the present invention]
FIG. 1 is an explanatory diagram for explaining a manufacturing method according to an embodiment of the present invention (hereinafter, the present embodiment).

The method for manufacturing the circuit board according to the present embodiment includes the insulating layer 11, the first and second circuits 12, 13a, the first and second cured layers 30a and 50a, and the first, first, as shown in FIG. 1E. This is a method for manufacturing a circuit board 1 including the second metal foils 20 and 40. Specifically, the method for manufacturing a circuit board according to the present embodiment includes the following steps (I) to (III).

Here, the first surface side 11X is the side on which the first circuit 12 is formed with respect to the insulating layer 11, and the second surface side 11Y is the metal layer 13 with respect to the insulating layer 11. Refers to the side to which is joined.

(I) An insulating layer 11 containing a thermoplastic resin, a first circuit 12 having a predetermined pattern formed on one surface of the insulating layer 11 on the first surface side 11X, and an insulating layer 11 on the second surface side 11Y. A step of preparing a core substrate 10 having a flat metal layer 13 bonded to another surface.

(II) On the first surface of the core substrate 10, a first adhesive layer 30 containing a resin component having a softening point lower than the softening point of the thermoplastic resin and a first metal foil 20 are arranged in this order and heated. The first molding step of laminating and integrating these by pressure molding.

(III) In the laminate 2 obtained in the first molding step (II), the metal layer 13 is patterned to form a second circuit 13a on the second surface of the core substrate 10, and then the core substrate 10 is formed. A second adhesive layer 50 and a second metal foil 40 containing a resin component having a softening point lower than the softening point of the thermoplastic resin are arranged in this order on the second surface of the above, and heat and pressure molding is performed. The second molding process of laminating and integrating these.

Here, the first surface of the core substrate 10 is the surface on which the first circuit 12 is formed, and the second surface of the core substrate 10 is the surface on which the second circuit 13a is formed.

[Step of preparing the core substrate 10 (I)]
In step (I), the core substrate 10 is prepared. The core substrate 10 includes an insulating layer 11, and a first circuit 12 having a predetermined pattern is formed on one surface of the insulating layer 11. A flat metal layer 13 is bonded to the other surface of the insulating layer 11.

The insulating layer 11 is composed of a resin composition containing a thermoplastic resin (hereinafter referred to as thermoplastic resin A). Since the thermoplastic resin A has a lower elastic modulus than the thermosetting resin, it is effective in reducing the linear expansion coefficient of the insulating layer 11 to prevent the circuit board 1 from warping, and also lowering the dielectric constant of the insulating layer 11. Since it is also excellent in dielectric properties such as, it is possible to obtain a circuit board 1 having excellent these characteristics. Therefore, it is preferable that the resin component in the resin composition constituting the insulating layer 11 does not contain a thermosetting resin and contains the thermoplastic resin A as the main component. Although it does not prevent the resin component from containing the thermosetting resin, in that case, it is preferable that the amount of the thermoplastic resin A is larger than that of the thermosetting resin in terms of mass ratio.

The thickness of the insulating layer 11 may be appropriately adjusted according to the intended use of the circuit board 1, preferably 3 to 750 μm, and more preferably 5 to 400 μm.

Examples of the thermoplastic resin A include polyamide (PA), nylon (registered trademark), polyacetal (POM), polycarbonate (PC), modified polyphenylene ether (m-PPE, modified PPE, m-PPO), polyester, and polyethylene terephthalate. (PET), glass fiber reinforced polyethylene terephthalate (GF-PET), polybutylene terephthalate (PBT), engineering plastics such as cyclic polyolefin (COP), polyphenylene sulfide (PPS), polytetrafluoroethylene (PTFE), polysulfone (PSF) , Polyetheralphon (PES), Acrylic Polyarylate (PAR), Liquid Crystal Polymer (LCP), Polyetheretherketone (PEEK), Thermoplastic Polyethylene (PI), Engineering Plastics such as Polyamideimide (PAI), etc. Be done. Of these, a liquid crystal polymer having a low dielectric constant is preferable in terms of reducing transmission loss. These may be used alone, or two or more kinds may be mixed and used. As the liquid crystal polymer, known ones can be used depending on the purpose, and a commercially available liquid crystal polymer may be used. Specific examples of the liquid crystal polymer include those exemplified in JP-A-9-309150.

The softening point of the thermoplastic resin A is not particularly limited because the level of heat resistance required differs depending on the intended use of the circuit board 1, but from the viewpoint of ensuring good heat resistance and mechanical properties of the circuit board 1. It is preferably 230 ° C. or higher, more preferably 250 ° C. or higher, and even more preferably 280 ° C. or higher. The thermoplastic resin A tends to be easily softened due to a large decrease in elastic modulus in a high temperature range. However, the higher the softening point of the thermoplastic resin A, the more this tendency can be alleviated. In the steps (II) and (III), the deformation of the insulating layer 11 in the heat and pressure molding is suppressed more effectively, and the circuit board 1 having high position accuracy of the circuit pattern can be easily obtained. Here, the "softening point" can be measured as the Vicat softening temp., And can be measured by, for example, the measuring method specified in JIS K-7206 (1999).

The resin composition may further contain an inorganic filler. As a result, characteristics such as low linear expansion coefficient, flame retardancy, and thermal conductivity can be imparted to the insulating layer 11.

Examples of the inorganic filler include silica particles such as spherical silica and crushed silica, molybdenum compounds such as molybdenum trioxide, zinc molybdate, ammonium molybdate, and magnesium molybdate, aluminum hydroxide, magnesium hydroxide, and aluminum silicate. , Magnesium silicate, talc, clay, mica and the like. These may be used alone, or two or more kinds may be mixed and used.

The content of the inorganic filler is not particularly limited and can be set according to the intended purpose. For example, the content of the inorganic filler may be 20 to 200% by mass with respect to the total mass of the resin components of the insulating layer 11.

The insulating layer 11 may include a fiber base material. The fiber base material may be appropriately selected according to the characteristics required by the intended use of the circuit board 1, and for example, a woven fabric or a non-woven fabric made of an inorganic fiber or an organic fiber can be used. Examples of the material of the fiber base material include inorganic fibers such as glass and organic fibers such as aramid and polyester. The thickness of the fiber base material is not particularly limited, and is, for example, 3 to 200 μm.

The first circuit 12 is formed in a predetermined pattern. The shape of the pattern is designed according to the purpose of use of the circuit board 1, and is not particularly limited. Examples of the material constituting the first circuit 12 include metal wiring such as copper, silver, aluminum, and stainless steel, and printed wiring using a conductive paste or the like.

Examples of the method for forming the first circuit 12 include a method of forming a pattern mainly by a photo-etching method and an electroless plating method, and a method of forming a pattern using a mask during sputtering, vapor deposition, and the like. In particular, a metal layer (metal foil) similar to the metal layer 13 described later is preferably patterned.

The metal layer 13 is flat (flat), is bonded to the other surface of the insulating layer 11, and covers the entire surface of the other surface of the insulating layer 11. As a result, during the heat-pressurizing molding in the first molding step (II), the second surface side 11Y of the core substrate 10 is supported by the flat metal layer 13, so that the thermoplastic resin A becomes Even if it is softened, the deformation of the insulating layer 11 can be suppressed.

Examples of the material constituting the metal layer 13 include metal foils such as copper, silver, aluminum, and stainless steel. The thickness of the metal layer 13 is not particularly limited as long as it can maintain a flat surface before and after the heat and pressure molding in the second molding step (III), and is preferably 2 to 400 μm. The metal layer 13 may be, for example, an electrolytic metal foil obtained by an electrolytic method or a rolled metal foil obtained by a rolling method.

[First molding process (II)]
(Arrangement)
In the first molding step (II), first, as shown in FIG. 1A, the first adhesive layer 30 and the first metal foil 20 are superposed and arranged on the first surface of the core substrate 10 in this order. ..

The first adhesive layer 30 is an insulating material obtained by forming a sheet of the resin composition (a) containing a resin component having a softening point lower than that of the thermoplastic resin A. As the resin composition (a), for example, one in which the main component of the resin component is a thermosetting resin in an uncured or semi-cured state, or one in which the main component is a thermoplastic resin can be used. Here, the softening point of the resin component can be measured as the Vicat softening temperature, similarly to the thermoplastic resin A.

When the resin component of the resin composition (a) contains a thermosetting resin as a main component, the resin composition (a) contains a thermosetting resin in an uncured or semi-cured state as an essential component, and is a curing agent and a curing accelerator. It can be prepared by appropriately adding an agent, an inorganic filler, a flame retardant, or the like according to the purpose. The resin composition (a) can also contain a smaller amount of thermoplastic resin. In this case, since the softening point of the resin component is mainly composed of a thermosetting resin in an uncured or semi-cured state, it may be difficult to prepare a measurement sample of the Vicat softening temperature. The melting start temperature of the resin component may be substituted as an approximate value of the softening point.

Examples of the thermosetting resin include epoxy resin, cyanate ester resin, polyfunctional maleimide resin, low molecular weight polyphenylene ether resin, terminal unsaturated functional group-modified polyphenylene ether resin, benzoxazine resin, vinyl ester resin and the like. .. Of these, epoxy resin is particularly preferable. The thermosetting resin may be flame-retardant by bromination, phosphorus modification, or the like. These thermosetting resins may be used alone or in combination of two or more.

The curing agent is not particularly limited as long as it can react with the thermosetting resin to form a crosslinked structure, and may be appropriately selected depending on the type of the thermosetting resin. For example, when the thermosetting resin contains an epoxy resin, for example, a diamine-based curing agent such as a primary amine or a secondary amine, a bifunctional or higher-functional phenol-based curing agent, an acid anhydride-based curing agent, dicyandiamide, etc. Examples thereof include low molecular weight polyphenylene ether compounds. These curing agents may be used alone or in combination of two or more.

Examples of the curing accelerator include imidazole compounds such as 2-ethyl-4-methylimidazole (2E4MZ), tertiary amine compounds, organic phosphine compounds, and metal soaps.

Examples of the inorganic filler include metal oxides such as silica, aluminum oxide, magnesium oxide and titanium oxide, metal hydroxides such as aluminum hydroxide and magnesium hydroxide, barium sulfate, calcium carbonate, magnesium carbonate and boron nitride. , Aluminum borate, barium titanate, strontium titanate, calcium titanate, magnesium titanate, bismuth titanate, talc, clay, mica powder and the like. Of these, silica is particularly suitable.

Examples of the flame retardant include halogen-based flame retardants such as bromine-containing compounds and non-halogen-based flame retardants such as phosphorus-containing compounds and nitrogen-containing compounds.

When the resin component of the resin composition (a) contains a thermoplastic resin as a main component, the resin composition (a) has a softening point lower than the softening point of the thermoplastic resin A contained in the insulating layer 11 of the core substrate 10. It can be prepared by using another thermoplastic resin having the above (hereinafter referred to as thermoplastic resin B) as an essential component and appropriately adding an inorganic filler, a flame retardant, or the like according to the purpose. The resin composition (a) may further contain a small amount of thermosetting resin.

Specific examples of the thermoplastic resin B include the same engineering plastics as those exemplified as specific examples of the thermoplastic resin A described above, but those having a softening point relatively lower than that of the thermoplastic resin A are selected. To.

The first adhesive layer 30 preferably has a sheet shape so that it can be placed on top of the core substrate 10. Specifically, for example, a resin sheet with a support formed by applying the resin composition (a) to a support such as a prepreg, a resin film, or a metal leaf in which a fiber base material is impregnated with the resin composition (a). And so on.

When the prepreg is used as the first adhesive layer 30, the same fiber base material as that mentioned in the description of the core substrate 10 can be used as the fiber base material. When the resin sheet with a support is used as the first adhesive layer 30, the resin sheet with a support is laminated so that the resin composition (a) is bonded onto the first surface of the core substrate 10. After transferring the resin composition (a) to the core substrate 10 side, the support may be peeled off and used. Here, it is also possible to use the first metal foil 20 as the support, and in this case, it is not necessary to peel off the first metal foil 20 after stacking on the first surface of the core substrate 10. , The heat and pressure molding described later can be performed as it is.

The thickness of the first adhesive layer 30 is not particularly limited, but the space between the circuits of the first circuit 12 is filled with the resin composition (a), and the first circuit 12 and the first metal foil 20 are combined. In order to ensure the insulating property, it is preferably larger than the thickness of the first circuit 12.

As the first metal foil 20, the same metal foil as those mentioned in the description of the core substrate 10 can be used, but when the metal foil is used after pattern processing as a circuit, a copper foil is preferable. In particular, in the case of a fine wiring circuit, it is preferable to use a thin copper foil having a thickness of 10 μm or less, or to use a copper foil with a carrier in which an ultrathin copper foil and a support copper foil are detachably joined.

In the first metal foil 20, the surface arranged to face the first adhesive layer 30 is preferably a roughened matte surface. As a result, the peel strength between the first metal foil 20 and the first hardened layer 30a can be improved by the anchor effect.

(Heat and pressure molding)
In the first molding step (II), the core substrate 10, the first adhesive layer 30, and the first metal foil 20 arranged as shown in FIG. 1A are laminated and integrated by heat and pressure molding. To do. As a result, as shown in FIG. 1B, the first circuit 12, the first cured layer 30a, and the first metal foil 20 are provided in this order on one surface of the insulating layer 11 on the first surface side 11X. A laminate 2 having a flat metal layer 13 on the other surface of the insulating layer 11 on the second surface side 11Y can be obtained.

At the time of this heat-press molding, the resin component contained in the resin composition (a) is softened or melted in the first adhesive layer 30, and the central portion of the core substrate 10 is filled while filling the space between the first circuits 12. Flows from to the periphery. Then, the stress associated with the resin flow acts on the first circuit 12 in the XY plane direction perpendicular to the thickness direction (Z direction) of the core substrate 10. At this time, since the second surface side 11Y of the core substrate 10 is supported by the flat metal layer 13, the insulating layer 11 is prevented from being deformed due to the stress due to the resin flow, and the first The position of the circuit 12 is less likely to shift. That is, even if the first adhesive layer 30 is softened or melted during heat-press molding and flows, the deformation of the insulating layer 11 is suppressed, and the positional deviation of the first circuit 12 is also suppressed.

As a method of heat-press molding the core substrate 10, the first adhesive layer 30, and the first metal foil 20, for example, the core substrate 10, the first adhesive layer 30, and the first metal foil 20 are formed between the hot plates. A hot press method (Open Type Hot Press) and a vacuum hot press method (Vacuum Type Hot Press) in which a first laminated body composed of the above is inserted, the temperature of the hot plate is heated to heat the first laminated body, and the first laminated body is heated and pressed at the same time. ) And so on.

The conditions for heat and pressure molding may be appropriately adjusted according to the materials of the insulating layer 11 and the first adhesive layer 30, but the temperature conditions include softening of the resin component contained in the first adhesive layer 30. It is preferably set in a temperature range higher than the point and lower than the softening point of the thermoplastic resin A constituting the insulating layer 11 of the core substrate 10.

For example, when the softening point of the thermoplastic resin A constituting the insulating layer 11 is 310 ° C. and the softening point of the resin component contained in the first adhesive layer 30 is 250 ° C., the temperature condition for heat and pressure molding is 260 ° C. It is preferable to set in the range of ~ 300 ° C. Further, when the softening point of the thermoplastic resin A constituting the insulating layer 11 is 300 ° C. and the softening point of the resin component contained in the first adhesive layer 30 is 120 ° C. (the first adhesive layer 30 is uncured or semi-cured). When the main component is a curable thermosetting resin, etc.), the molding temperature may be set in the range of 130 to 250 ° C. The pressure and molding time for heat-pressurizing molding can be appropriately set in consideration of moldability and the like.

[Second molding process (III)]
(Pattern processing)
In the second molding step (III), first, in the laminate 2 obtained in the first molding step (II), the metal layer 13 is patterned to form a second circuit on the second surface of the core substrate 10. Form 13a. As a result, as shown in FIG. 1C, the first circuit 12, the first cured layer 30a, and the first metal foil 20 are provided in this order on one surface of the insulating layer 11 on the first surface side 11X. A laminate 3 having the second circuit 13a on the other surface of the insulating layer 11 on the second surface side 11Y is obtained.

The shape of the pattern of the second circuit 13a can be appropriately set according to the purpose of use of the circuit board 1. Further, the shape of the pattern of the second circuit 13a may be the same as or different from that of the first circuit 12. The pattern processing method is not particularly limited, and examples thereof include known methods such as a photo etching method.

(Arrangement)
In the second molding step (III), as shown in FIG. 1D, the second adhesive layer 50 and the second metal foil 40 are arranged in this order on the second surface of the core substrate 10 in the laminated body 3. ..

Like the first adhesive layer 30, the second adhesive layer 50 is an insulating material obtained by forming a sheet of the resin composition (b) containing a resin component having a softening point lower than the softening point of the thermoplastic resin A. .. Examples of the resin component constituting the resin composition (b) include the same components as those of the first adhesive layer 30 (resin composition (a)). Further, the specific composition component of the resin composition (b) may be the same as or different from that of the first adhesive layer 30 (resin composition (a)), and the circuit board 1 may be used. It can be decided according to the purpose.

Further, the form of the second adhesive layer 50 also includes a prepreg, a resin sheet with a support, and the like as in the case of the first adhesive layer 30, and even if the form is the same as that of the first adhesive layer 30, it is different. It may be in the form, and can be determined according to the purpose of use of the circuit board 1.

The second metal foil 40 may be the same as the first metal foil 20, and may be the same as the first metal foil 20 or may have a different thickness, properties, and shape. It can be determined according to the purpose of use of the circuit board 1.

(Heat and pressure molding)
In the second molding step (III), as shown in FIG. 1D, the laminate 3, the second adhesive layer 50, and the second metal foil 40 are arranged in this order, and further heat-press molded to form them. Laminate and integrate. As a result, as shown in FIG. 1E, the first circuit 12, the first cured layer 30a, and the first metal foil 20 are provided in this order on one surface of the insulating layer 11 on the first surface side 11X. A circuit board 1 having a second circuit 13a, a second cured layer 50a, and a second metal foil 40 on the other surface of the insulating layer 11 on the second surface side 11Y is obtained in this order.

At the time of this heat-press molding, the resin composition (b) is once melted in the second adhesive layer 50, and flows from the central portion to the peripheral portion of the core substrate 10 while filling the space between the second circuits 13a. To do. Then, the stress associated with the resin flow acts on the second circuit 13a in the XY plane direction perpendicular to the thickness direction (Z direction) of the core substrate 10. At this time, since the first surface side 11X of the core substrate 10 is plane-supported by the first circuit 12 and the first cured layer 30a, the insulating layer 11 is unlikely to be deformed due to stress due to resin flow. .. Therefore, the position of the second circuit 13a is difficult to move. That is, even if the thermoplastic resin A softens during heat-press molding, the deformation of the insulating layer 11 is suppressed, and the positional deviation of the second circuit 13a is also suppressed. Therefore, the circuit board 1 has high positional accuracy of the first circuit 12 and the second circuit 13a, and has high electrical reliability.

As a method of heat-press molding the laminate 3, the second adhesive layer 50 and the second metal foil 40, for example, it can be carried out in the same manner as in the heat-press molding in the first molding step (II).

The circuit board 1 is printed by, for example, using a subtractive method or the like to form a circuit by removing a part of the first metal foil 20 and the second metal foil 40 of the circuit board 1 by etching. It can be used as a wiring board. In this case, vias can be formed by laser machining or drilling to form through holes or blind via holes for electrical connection between layers, but as described above, the first circuit 12 and the second Since the position accuracy of the circuit 13a of the above is high, the reliability of the interlayer connection is high. Further, the obtained printed wiring board can be used as a core substrate of a multilayer printed wiring board in which resin layers and circuits are newly alternately stacked by a build-up method on one side or both sides thereof.

1 Circuit board 2, 3 Laminated body 10 Core board 11 Insulation layer 12 First circuit 13 Metal layer 13a Second circuit 20 First metal foil 30 First adhesive layer 30a First hardened layer 40 Second metal Foil 50 Second adhesive layer 50a Second hardened layer

Claims (5)

It is bonded to an insulating layer containing a thermoplastic resin, a first circuit having a predetermined pattern formed on one surface of the insulating layer on the first surface side, and another surface of the insulating layer on the second surface side. The process of preparing a core substrate having a flat metal layer and
A first adhesive layer containing a resin component having a softening point lower than that of the thermoplastic resin and a first metal foil are arranged in this order on the first surface of the core substrate, and heat and pressure molding is performed. In the first molding process of laminating and integrating these,
In the laminate obtained in the first molding step, the metal layer is patterned to form a second circuit on the second surface of the core substrate, and then the second circuit is formed.
On the second surface of the core substrate, a second adhesive layer containing a resin component having a softening point lower than the softening point of the thermoplastic resin and a second metal foil are arranged in this order, and heat and pressure molding is performed. The second molding process, which integrates these layers by
Including
A method for manufacturing a circuit board, wherein the first metal foil covers the entire first surface of the core substrate via the first adhesive layer. The method for manufacturing a circuit board according to claim 1, wherein the thermoplastic resin contains a liquid crystal polymer. The method for producing a circuit board according to claim 1 or 2, wherein the first adhesive layer and the second adhesive layer contain an uncured or semi-curable thermosetting resin as the resin component. The production of the circuit board according to claim 1 or 2, wherein the first adhesive layer and the second adhesive layer contain another thermoplastic resin having a softening point lower than the softening point of the thermoplastic resin as the resin component. Method. The method for manufacturing a circuit board according to any one of claims 1 to 4, wherein the insulating layer has a thickness of 3 to 750 μm.

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