JP4349882B2 - Wiring board and semiconductor device - Google Patents

Description

  The present invention relates to a wiring board for mounting a semiconductor element such as a semiconductor integrated circuit element.

  In general, current electronic devices are required to be reduced in size, thickness, and weight as represented by mobile communication devices, and wiring boards for mounting semiconductor elements used in such electronic devices are required. In addition, downsizing, thinning, and multi-terminal are required. In order to achieve this, the width of the wiring conductor including the signal conductor in the wiring board is narrowed and the interval between the wiring conductors is narrowed. Further, the wiring conductor layer and the insulating layer are laminated in multiple layers. By doing so, the wiring board is made high-density wiring.

  As a wiring board for such high-density wiring, a wiring conductor made of metal foil is disposed between the surface of the insulating substrate formed by laminating a plurality of insulating layers impregnated with a thermosetting resin on a heat-resistant fiber base and between the insulating layers. There is known a wiring board formed as described above. Alternatively, a resin layer made of a thermosetting resin and a wiring conductor made of a plated metal layer are alternately laminated on the upper and lower surfaces of the insulating substrate in which the wiring conductor made of metal foil is disposed between the surface and the insulating layer in this way. There is a known wiring board.

  Insulating substrates used for the above-mentioned wiring boards are generally made of uncured epoxy on glass fiber base material, which is made of a plurality of cured insulating layers obtained by impregnating a glass fiber base material with an epoxy resin and thermosetting it. It is manufactured by laminating via an adhesive layer impregnated with resin and thermosetting the epoxy resin of the adhesive layer. In addition, wiring conductors made of metal foil disposed inside and on the surface of the insulating substrate are formed by pasting copper foil on the upper and lower surfaces of the insulating layer and etching the copper foil into a wiring pattern. It is arranged in a state protruding from the surface of each insulating layer by the thickness of the copper foil. For this reason, the adhesive layer is not sufficiently filled between the wiring conductors disposed between the insulating layers of the insulating substrate, resulting in gaps, and moisture enters the gaps to electrically insulate the wiring conductors. There was a problem that would decrease. In addition, the surface of the insulating substrate becomes uneven due to the difference in height between the surface of the insulating layer and the surface of the wiring conductor, and the wiring conductor composed of the resin layer and the plated metal layer is alternately laminated thereon. In this case, it was difficult to satisfactorily form a fine wiring conductor using a plated metal layer.

  Therefore, in order to solve such problems, an insulating sheet containing an uncured thermosetting resin is used as a wiring conductor made of a metal foil previously formed in a wiring pattern on the surface of a transfer film made of a heat resistant resin. After being pressed and embedded in the surface of the wire, the transfer film is removed to create a plurality of uncured insulating layers onto which the wiring conductor has been transferred. A method for manufacturing an insulating substrate and arranging a wiring conductor made of metal foil between the surface of the insulating substrate and an insulating layer has been proposed.

  According to this method, the wiring conductor made of the metal foil can be embedded in the uncured insulating layer so that the surface thereof and the surface of the wiring conductor are substantially flush with each other at the time of transfer. There is no gap between the layer and the wiring conductor, and no irregularities due to the wiring conductor are formed on the surface of the insulating substrate. Therefore, there is no reduction in electrical insulation due to moisture entering between the wiring conductors arranged on the insulating substrate, and when a wiring conductor composed of a resin layer and a plated metal layer is laminated on the insulating substrate. Can satisfactorily form a fine wiring conductor with a plated metal layer.

By the way, in such a wiring board, a metal foil used as a wiring conductor disposed on the surface of an insulating substrate or between insulating layers generally has a metal film formed by electrolytic plating on the surface of an electrodeposition drum having a smooth surface. An electrolytic metal foil formed by the method of precipitation is used. One surface of the electrolytic metal foil becomes a rough surface called an uneven mat surface having an arithmetic average roughness of 1 to 2 μm by the grain growth of metal plating, and the other surface has an arithmetic average roughness of 0.1 to 0. It becomes a fine rough surface called a shiny surface corresponding to a 3 μm drum surface. Moreover, the fine rough surface side is adhere | attached with respect to the transfer film, and the main surface by which the side embedded in the insulating layer of metal foil is a rough surface with an unevenness | corrugation. Since the metal foil is etched into a wiring pattern, the side surface is an etched surface having an arithmetic average roughness of 0.05 to 0.1 μm.
Japanese Patent No. 3037662

  However, when an insulating substrate in which a plurality of insulating layers are laminated is obtained by the above method and a wiring conductor made of a metal foil is disposed between the surface of the insulating substrate and the insulating layer, the side embedded in the insulating layer of the wiring conductor The main surface of this is a rough surface with irregularities, so the adhesive strength with the insulating layer is large, but the other main surface is a fine rough surface, so other insulating layers laminated on this fine rough surface When the heat for mounting the semiconductor element on the wiring board or the heat generated during operation of the semiconductor element is applied, there is a gap between the fine rough surface of the wiring conductor and the insulating layer. There is a problem that a crack starting from the gap is generated and the surrounding wiring conductor is cut.

  Therefore, after bonding the rough surface side of the metal foil to the transfer film and etching it into a wiring pattern, the exposed surface of the metal foil is chemically treated to chemically roughen all the wiring conductors. It has been proposed to transfer the surface to an insulating sheet after making the surface rough. However, in the wiring conductor disposed on the surface of the insulating substrate, a rough surface with large irregularities is exposed. Therefore, when the electrode of the semiconductor element or the wiring conductor of the external electric circuit board is connected to this, the wiring conductor And a good connection between the semiconductor element and the external electric circuit board become difficult. In addition, when a wiring conductor made of a resin layer and a plated metal layer is laminated on the surface of the insulating substrate, a good connection between the wiring conductor made of the metal foil on the surface of the insulating substrate and the wiring conductor made of the plated metal layer is achieved. It becomes difficult.

  The present invention has been completed in view of the problems of the prior art, and the object of the present invention is to provide a wiring conductor even when heat is generated when a semiconductor element is mounted on a wiring board or when the semiconductor element is activated. When the wiring conductor of the semiconductor element or the external electric circuit board is connected to the wiring conductor made of the metal foil on the surface of the insulating substrate, there is no separation between the semiconductor element and the external electric circuit board. A wiring board having excellent electrical connection reliability with a wiring conductor made of copper foil when a wiring conductor made of a resin layer and a plated metal layer is laminated on the surface of the insulating board; An object of the present invention is to provide a wiring board having excellent electrical connection reliability with a wiring conductor made of a plating conductor.

The wiring board of the present invention has a pattern of an insulating substrate formed by laminating a plurality of insulating layers impregnated with a thermosetting resin, and a metal foil with one main surface being a rough surface and the other main surface being a fine rough surface. A first wiring conductor disposed on the surface of the insulating substrate, processed and embedded in the surface of the insulating layer , one main surface being a rough surface and the other main surface being a rough surface the metal foil patterned to made by embedded on the surface of the insulating layer, the second wiring conductor disposed between layers of the insulating layer of the insulating substrate, a wiring board having a said In the first wiring conductor, the rough surface and side surfaces are chemically roughened, and the rough surface side is embedded in the surface of the outermost insulating layer, and the second wiring conductor is fine rough surface and side is embedded in the surface of the fine rough surface is the insulating layer with and is chemically roughened The insulating substrate is laminated with a resin layer having an opening that exposes a part of the first wiring conductor on a surface thereof, and a main surface of the first wiring conductor on a side in contact with the resin layer is arithmetically operated. An arithmetic average roughness of 0.05 is obtained by etching the surface of the fine roughness chemically roughened to an average roughness of 0.3 to 0.7 μm and exposed from the opening of the first wiring conductor. It is smoothed to ˜0.1 μm, and a plated metal layer or solder is deposited on the smoothed surface .

The semiconductor device of the present invention is characterized in that an electrode of a semiconductor element is electrically connected to a portion exposed from the opening of the first wiring conductor of the wiring board of the present invention .

  According to the wiring board of the present invention, the first wiring conductor disposed on the surface of the insulating substrate has its rough surface and side surfaces chemically roughened, and the rough surface side is the outermost insulating layer. Since it is embedded, the rough surface and the unevenness of the side surface and the thermosetting resin of the insulating layer are engaged and firmly adhered to the outermost insulating layer, and the main surface on the side exposed to the surface of the insulating substrate Since the surface becomes fine, large irregularities are not formed, so that the wiring conductor and the semiconductor element or the external electric circuit board can be connected well. Further, the second wiring conductor disposed between the insulating layers has a finely roughened surface and side surfaces chemically roughened, and the roughened roughened surface side is embedded in the insulating layer. Therefore, the entire surface becomes a roughened surface, and the unevenness formed on the entire surface and the thermosetting resin of the insulating layer are engaged with each other and firmly adhered to the resin layer, and peeling between the insulating layer is generated. Absent.

  The arithmetic mean roughness of the chemically roughened rough surface of the first wiring conductor is 1 to 2 μm, and the chemically roughened fine roughened surface and the side surface of the second wiring conductor are When the arithmetic average roughness is 0.3 to 0.7 μm, the first and second wiring conductors and the insulating layer are bonded extremely firmly.

  Further, when a resin layer having an opening exposing a part of the first wiring conductor is laminated on the surface of the insulating substrate, the surface in contact with the resin layer of the first wiring conductor has an arithmetic average roughness of 0. When the surface is chemically roughened to 3 to 0.7 μm, the unevenness of the roughened rough surface and the resin layer are engaged, and the first wiring conductor and the resin layer are firmly adhered to each other. To do.

  Further, when a plated metal layer or solder is applied to the surface exposed from the opening of the first wiring conductor, the arithmetic average roughness of the surface exposed from the first opening is 0.05. When the surface is smoothed by etching so as to have a thickness of about 0.1 μm, the first wiring conductor exposed from the opening and the plated metal layer or solder are firmly bonded.

  Next, the wiring board of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a sectional view showing a first embodiment for carrying out the present invention, and FIG. 2 is an enlarged sectional view of an essential part thereof. In these drawings, 1 is an insulating layer, 2 is an insulating substrate, 3a is a first wiring conductor made of a metal foil disposed on the surface of the insulating substrate 2, and 3b is a metal disposed between the insulating layers 1. A second wiring conductor 4 made of foil is a through conductor, and an insulating substrate 2 is formed by laminating and integrating a plurality of insulating layers 1, and the first wiring conductor 3a and the first wiring conductor 3a are formed on the surface of the insulating substrate 2. The second wiring conductor 3b is disposed between the insulating layers 1, and the upper and lower wiring conductors 3a and 3b are electrically connected by the through conductors 4 provided through the insulating layer 1. A wiring board according to a first embodiment for carrying out the above is configured. In the wiring board of this example, an example is shown in which the resin layer 5 functioning as a solder resist is deposited on the upper and lower surfaces of the insulating substrate 2 so as to expose a part of the first wiring conductor 3a. .

  Each insulating layer 1 constituting the insulating substrate 2 is formed by impregnating a heat-resistant fiber base material made of a heat-resistant fiber non-woven fabric or woven fabric such as aramid fiber or glass fiber with a thermosetting resin, each of which is made of a metal foil. The first wiring conductor 3a and the second wiring conductor 3b are supported, and the electrical connection between the first wiring conductor 3a and the second wiring conductor 3b that are positioned above and below, and between the second wiring conductors 3b. It has a function of maintaining a good insulating property. Such an insulating layer 1 is obtained by applying various processing to an insulating sheet having a thickness of about 50 to 150 μm obtained by impregnating a heat-resistant fiber base material with an uncured thermosetting resin composition, These are integrated with each other by laminating a plurality of layers and thermosetting them.

  The insulating sheet for forming the insulating layer 1 is a liquid obtained by mixing a non-woven fabric or woven fabric of heat-resistant fibers such as aramid fibers and glass fibers with a thermosetting resin, a cross-linking agent, an elastomer and an appropriate solvent. It is manufactured by immersing in the thermosetting resin composition of the above, or by applying and impregnating this composition to a nonwoven fabric or woven fabric of heat-resistant fibers such as aramid fibers and glass fibers. When the heat resistant fiber base material is composed of a woven fabric, the weaving method is not particularly limited, and generally a woven fabric such as plain weave, twill weave, satin weave, or the like is used. As for the content rate of such a heat resistant fiber base material, 50-130 mass parts is preferable with respect to 100 mass parts of thermosetting resins. When the content rate of the heat-resistant fiber base is less than 50 parts by mass with respect to 100 parts by mass of the thermosetting resin, the thermosetting resin flows when the insulating layer 1 is cured, and the first wiring conductor 3a and the second wiring conductor 3a. The wiring conductor 3b tends to be distorted, and if it exceeds 130 parts by mass, the heat-resistant fiber base tends to be unable to be satisfactorily impregnated with the thermosetting resin. Therefore, the content of the heat resistant fiber base material is preferably 50 to 150 parts by mass with respect to 100 parts by mass of the thermosetting resin.

  As the thermosetting resin contained in the thermosetting resin composition constituting the insulating sheet, an allyl-modified polyphenylene ether resin, an epoxy resin, a modified polyolefin resin, or the like is used. The molecular weight of the thermosetting resin is preferably in the range of 10,000 to 500,000 so that the first and second wiring conductors 3a and 3b described later can be easily transferred.

  As the crosslinking agent, a triazine compound such as triallyl isocyanurate is used. It is preferable that the content rate of a crosslinking agent is 1-10 mass parts with respect to 100 mass parts of thermosetting resins. When the content of the cross-linking agent is less than 1 part by mass with respect to 100 parts by mass of the thermosetting resin, the insulating substrate 1 tends to absorb moisture without increasing the cross-linking density of the insulating layer 1, and more than 10 parts by mass. And the insulating layer 1 tends to become brittle. Therefore, it is preferable that the content rate of a crosslinking agent is 1-10 mass parts with respect to 100 mass parts of thermosetting resins.

  Furthermore, thermoplastic elastomers such as styrene-ethylene-butylene-styrene (SEBS) and styrene-ethylene-propylene-styrene (SEPS) are used as the elastomer. As for the content rate of an elastomer, 10-40 mass parts is preferable with respect to 100 mass parts of thermosetting resins. When the elastomer content is less than 10 parts by mass with respect to 100 parts by mass of the thermosetting resin, the insulating layer 1 tends to be brittle, and when it exceeds 40 parts by mass, the rigidity of the insulating layer 1 tends to be low. Therefore, the content of the elastomer is preferably 10 to 40 parts by mass with respect to 100 parts by mass of the thermosetting resin.

  The first wiring conductor 3a disposed on the surface of the insulating substrate 2 and the second wiring conductor 3b disposed between the insulating layers 1 are each made of copper, aluminum, silver or the like having a thickness of about 5 to 50 μm. Each of the electrodes of the semiconductor element mounted on the wiring board functions as a part of a conductive path that electrically connects to the wiring conductor of the external electric circuit board. These wiring conductors 3 a and 3 b include a signal conductor having a width of about 20 to 200 μm and a large-area ground or power supply conductor. Generally, fine high-density wiring is applied on the surface of the insulating substrate 2. Has been. For example, a part of the first wiring conductor 3 a disposed on the upper surface of the insulating substrate 2 forms a semiconductor element connection pad that is electrically connected to the electrode of the semiconductor element 6 via the solder bump 7 a. In addition, a part of the first wiring conductor 3a disposed on the lower surface of the insulating substrate 2 forms an external connection pad that is electrically connected to the wiring conductor of the external electric circuit board via the solder bumps 7b.

  Such wiring conductors 3a and 3b can peel an electrolytic metal foil having a rough surface called a mat surface and a fine rough surface called a shiny surface on a transfer film made of a heat-resistant resin such as polyethylene terephthalate via an adhesive. Then, after patterning into a predetermined wiring pattern by etching, the exposed surface of the patterned metal foil is chemically roughened to form wiring conductors 3a and 3b on the transfer film. The wiring conductors 3a and 3b on the transfer film are embedded in the surface of the insulating sheet for the insulating layer 1 by thermocompression using a hot press, and laminated with the insulating sheet, Arranged between the insulating layers 1.

  In the first embodiment, the first wiring conductor 3a disposed on the surface of the insulating substrate 2 is manufactured by sticking a fine rough surface of a metal foil on a transfer film. The rough surface and side surfaces are chemically roughened, and the rough surface side is embedded in the surface of the insulating layer 1. On the other hand, the 2nd wiring conductor 3b arrange | positioned between the insulating layers 1 is manufactured by sticking the rough surface of metal foil on a transfer film, and a fine rough surface and a side surface are chemically roughened. The fine rough surface side is embedded in the surface of the insulating layer 1. This is important in the first embodiment.

  The first wiring conductor 3a disposed on the surface of the insulating substrate 2 has a rough surface and side surfaces that are chemically roughened, and the rough surface side is embedded in the surface of the insulating layer 1. The roughened rough surface and side surface irregularities and the thermosetting resin of the insulating layer 1 mesh with each other and firmly adhere to the insulating layer 1, and the surface exposed to the surface of the insulating substrate 2 becomes a fine rough surface. Therefore, large unevenness is not formed on the exposed surface. Therefore, it is possible to satisfactorily connect the first wiring conductor 3a to the semiconductor element 6 and the external electric circuit board.

  Further, the second wiring conductor 3b disposed between the insulating layers 1 has a finely roughened surface and side surfaces chemically roughened, and the finely roughened surface side is embedded in the surface of the insulating layer 1. For this reason, the thermosetting resin of the insulating layer 1 on the side where the second wiring conductor 3b is embedded and the finely roughened surface of the wiring conductor 3b and the unevenness of the side surface mesh with each other and firmly adhere to each other. At the same time, the unevenness of the rough surface on the opposite side and the thermosetting resin of the insulating layer 1 in contact therewith are engaged and firmly adhered to the upper and lower insulating layers 1.

  Therefore, according to the wiring board of the first embodiment for carrying out the present invention, even if heat is generated when the semiconductor element 6 is mounted or heat generated when the semiconductor element 6 is activated, the wiring conductor 3a or Peeling does not occur between 3b and the insulating layer 1, and a wiring board having excellent electrical connection reliability with the semiconductor element 6 and the external electric circuit board can be provided.

  The first wiring conductor 3a disposed on the surface of the insulating substrate 2 has an adhesive force with the insulating layer 1 when the arithmetic mean roughness of the chemically roughened rough surface is less than 1 μm. If it becomes weak and stress is applied when connecting the semiconductor element 6 or external electric circuit board to the wiring conductor 3a, the risk of peeling off from the insulating substrate 2 increases. When forming the conductor 3a, it becomes difficult to form a fine wiring pattern satisfactorily. Therefore, the arithmetic mean roughness of the chemically roughened rough surface of the first wiring conductor 3a disposed on the surface of the insulating substrate 2 is preferably 1 to 2 μm.

  Further, the first wiring conductor 3a disposed on the surface of the insulating substrate 2 has a side surface and the insulating layer 1 having an arithmetic average roughness of the chemically roughened side surface of less than 0.3 μm. The bonding force tends to be weak, and if it exceeds 0.7 μm, it is difficult to satisfactorily form a fine wiring pattern when forming the first wiring conductor 3a. Therefore, it is preferable that the arithmetic average roughness of the roughened side surface of the first wiring conductor 3a disposed on the surface of the insulating substrate 2 is 0.3 to 0.7 μm.

  Further, the second wiring conductor 3b disposed between the insulating layers 1 has a chemically rough surface and an arithmetic average roughness of the side surface of less than 0.3 μm. The adhesion between the insulating layer 1 and the insulating layer 1 increases, and when the thickness exceeds 0.7 μm, it is difficult to form a fine wiring pattern when forming the wiring conductor 3b. Become. Therefore, the second wiring conductor 3b disposed between the insulating layers 1 has an arithmetic average roughness of 0.3 to 0.7 μm on the chemically roughened fine surface and side surface. preferable. In addition, the second wiring conductor 3b disposed between the insulating layers 1 has a small adhesive force with the insulating layer 1 when the arithmetic average roughness of the rough surface is less than 1 μm, When the thickness exceeds 2 μm, it is difficult to form a fine wiring pattern when forming the second wiring conductor 3b. Therefore, it is preferable that the arithmetic mean roughness of the rough surface of the second wiring conductor 3b disposed between the insulating layers 1 is 1 to 2 μm.

  Further, the through conductor 4 provided through the insulating layer 1 is made of, for example, an electrically conductive material containing an alloy powder composed of 70 to 90% by mass of tin, silver, bismuth, and copper and a thermosetting resin. Between the first wiring conductor 3a and the second wiring conductor 3b, the alloy powders contained in the through conductor 4 are in contact with each other and the alloy powder is in contact with the copper foil constituting the wiring conductors 3a and 3b. And the second wiring conductors 3b are electrically connected.

  The through conductor 4 has a through hole having a diameter of about 30 to 200 μm drilled by laser processing on the insulating sheet for the insulating layer 1 before the copper foil for the wiring conductors 3a and 3b is embedded. A metal paste containing an alloy powder composed of 70 to 90% by mass of tin, silver, bismuth and copper and an uncured thermosetting resin is filled in the through hole, and the metal paste is insulated for the insulating layer 1. It is formed by thermosetting together with the sheet.

  In addition, as for content of the metal powder in the electroconductive material which forms the penetration conductor 4, 80-95 mass% is preferable. If the content of the metal powder is less than 80% by mass, good contact between the metal powders in the conductive material tends to be hindered and the electrical resistance of the through conductor 4 tends to increase. There is a tendency that the viscosity of the metal paste for the material is increased and good filling into the through-hole is hindered. Therefore, the content of the metal powder in the conductive material forming the through conductor 4 is preferably 80 to 95% by mass.

  The metal powder contained in the conductive material for the through conductor 4 is made of an alloy containing tin, silver, bismuth, and copper, and preferably contains 70 to 90% by mass of tin. Furthermore, the average particle size of the metal powder is preferably 5 to 10 μm. If the average particle size is less than 5 μm, the viscosity of the metal paste for the conductive material tends to be high, and there is a tendency to prevent good filling into the through-holes. In particular, the electrical resistance of the through conductor 4 tends to increase. Therefore, the average particle diameter of the metal powder contained in the conductive material for the through conductor 4 is preferably 5 to 10 μm.

  The thermosetting resin of the through conductor 4 is preferably a triazine-based thermosetting resin such as triallyl cyanurate, triallyl isocyanurate, trisepoxypropyl isocyanurate, or tris (2-hydroxyethyl) isocyanurate.

  Further, a resin layer 5 having an opening for exposing a central portion of a semiconductor element connection pad or an external connection pad formed as a part of the first wiring conductor 3 a is laminated on the upper and lower surfaces of the insulating substrate 2. The resin layer 5 is made of a thermosetting resin such as an epoxy resin, and functions as a solder resist for preventing the semiconductor connection pads and the external connection pads from being electrically short-circuited by the solder bumps 7a and 7b. A sheet of uncured thermosetting resin having photosensitivity is attached to the upper and lower surfaces of the insulating substrate 2, exposed and developed, and then ultraviolet light and heat cured. In addition, when the resin layer 5 is laminated | stacked on the surface of the insulated substrate 2, the surface where the 1st wiring conductor 3a is in contact with the resin layer 5 is chemically 0.3-0.7 micrometer so that arithmetic mean roughness may be 0.3-0.7 micrometer. The surface is preferably a finely roughened surface. When the surface of the first wiring conductor 3a that is in contact with the resin layer 5 is a finely roughened surface that is chemically roughened so as to have an arithmetic average roughness of 0.3 to 0.7 μm, it is chemically roughened. The unevenness of the fine surface and the resin of the resin layer 5 mesh with each other, and the resin layer 5 and the first wiring conductor 3a in contact with the resin layer 5 are firmly adhered. The surface of the first wiring conductor 3a exposed from the opening of the resin layer 5 is coated with a plated metal layer such as nickel or gold or solder such as a lead-tin alloy or tin-silver alloy. As a result, the bondability with the solder bumps 7a and 7b is good. When the plated metal layer or solder is applied to the surface of the first wiring conductor 3a in this way, the surface of the first wiring conductor 3a to which the plated metal layer or solder is applied is arithmetic average roughness. It is preferably smoothed by microetching so as to be 0.05 to 0.1 μm. The surface of the first wiring conductor 3a on which the plated metal layer or the solder is applied is smoothed by microetching so that the arithmetic average roughness is 0.05 to 0.1 μm. 3a and the plating metal layer and solder adhere firmly.

  The wiring board of this example becomes a semiconductor device by electrically connecting the electrodes of the semiconductor element 6 to the semiconductor element connection pads exposed from the resin layer 5 through the solder bumps 7a, and the external connection pads in this semiconductor device. Is electrically connected to the wiring conductor of the external electric circuit board via the solder bumps 7b, so that it is mounted on the external electric circuit board.

  Such a wiring board is manufactured by the method described below.

First, for example, when the metal foil is a copper foil, the metal foil has a current density of several tens between the electrodeposition drum (cathode body) immersed in an electrolytic solution containing copper ions and the lead container (anode body). A current of ˜100 A / dm ² is applied to deposit a copper foil of about 10 to 30 μm on the surface of the electrodeposition drum, and then the copper foil is peeled off from the surface of the electrodeposition drum. At this time, the surface on the electrodeposition drum side becomes a fine rough surface called a shiny surface having an arithmetic average roughness of 0.1 to 0.3 μm corresponding to the surface of the electrodeposition drum, and copper crystals are precipitated on the opposite surface. As a result, the arithmetic average roughness formed by growing in a hump shape is a rough surface called a mat surface having a thickness of 1 to 2 μm.

  Next, the copper foil is attached to one side of a transfer film made of a heat resistant resin such as polyethylene terephthalate having a thickness of about 20 to 50 μm via an adhesive. At this time, the copper foil for the first wiring conductor 3 a disposed on the surface of the insulating substrate 2 is attached with the fine rough surface side thereof being the transfer film side, and is disposed between the insulating layers 1. The copper foil for the wiring conductor 3b is adhered with the rough surface side set to the transfer film side.

  Next, an etching resistant resin is applied onto the copper foil adhered to the transfer film, and the etching resistant resin is exposed and developed to coat the copper foil in the wiring pattern of the wiring conductors 3a and 3b. After that, this is immersed in a ferric chloride solution to remove the exposed portion of the copper foil by etching, and then the etching-resistant resin layer is peeled off to form the wiring conductors 3a and 3b on the transfer film. . Thereafter, the exposed surfaces of the wiring conductors 3a and 3b are chemically roughened by acid treatment. At this time, the first wiring conductor 3a disposed on the surface of the insulating substrate 2 has an arithmetic average roughness of the exposed rough surface of 1 to 2 μm and an arithmetic average roughness of the exposed side surface of 0.3 to 0. Roughen to 7 μm. On the other hand, the 2nd wiring conductor 3b arrange | positioned between the insulating layers 1 is roughened so that the arithmetic mean roughness of the exposed fine rough surface and side surface may be 0.3-0.7 micrometer. In this roughening treatment, many protrusions having a pointed shape can be formed by chemical chemical treatment such as hydrochloric acid, sulfuric acid, nitric acid, acetic acid, and formic acid. In particular, an acid solution is used for the wiring conductor 3a. It is desirable to spray on 3b.

  Next, a plurality of insulating sheets for the insulating layer 1 formed by impregnating a heat-resistant fiber base material with an uncured thermosetting resin composition are prepared, and the through conductors 4 are applied to these insulating sheets by laser light irradiation. A through-hole for forming is drilled. Such a through-hole is formed by sticking a protective film on the surface of the insulating sheet and irradiating a laser beam such as a carbon dioxide laser or a YAG laser from above.

  Next, a metal paste made of conductive powder and uncured thermosetting resin is filled into the through holes formed in the insulating sheet for the insulating layer 1. Filling the through hole with metal paste is performed by screen printing, and as a mask for printing, use a metal mask having a hole corresponding to the through hole or a protective film itself attached when forming the through hole. Can do.

  Next, after peeling off the protective film from the insulating sheet for the insulating layer 1, the wiring conductors 3a and 3b formed on the transfer film and the metal paste in the through hole are in contact with the wiring conductor on the surface of the insulating sheet. After 3a and 3b are thermocompression-bonded and embedded using a hot press, the transfer film is peeled off from the insulating sheet to transfer the wiring conductors 3a and 3b. Thermocompression bonding is performed by applying pressure for several minutes using a hot press machine under conditions of a temperature of 100 to 150 ° C. and a pressure of 0.5 to 5 MPa. At this time, as for the 1st wiring conductor 3a arrange | positioned on the surface of the insulated substrate 2, the rough surface side chemically chemically roughened is embedded in an insulating sheet, and a fine rough surface is exposed to the surface. In addition, the second wiring conductor 3b disposed between the insulating layers 1 has a chemically roughened fine rough surface side embedded in an insulating sheet, and the rough surface is exposed on the surface.

  In thermocompression bonding, it is better to perform only pressurization prior to heating. If the heating is performed first, the transfer film is stretched by heat, and accurate alignment between the wiring conductors 3a and 3b and the through conductor 4 tends to be difficult. Therefore, it is preferable to perform only the pressurization prior to the heating in the thermocompression bonding.

  Further, it is desirable that the insulating sheet for the insulating layer 1 is supplied in a state of being cut one by one, not a roll-like continuous body. This is because the wiring conductors 3a and 3b are usually supplied in a roll-like continuum, so that the position of the wiring conductors 3a and 3b is adjusted by moving the insulating sheet and adjusting the position finely. This is because the alignment mechanism becomes compact. The alignment between the wiring conductors 3a and 3b and the insulating sheet can be optically performed by an image recognition device, but various other known methods may also be used.

  Finally, a plurality of insulating sheets to which the wiring conductors 3a and 3b are transferred are connected with a metal paste between the wiring conductors 3a and 3b transferred to each insulating sheet and between 3b with a through-hole filled. In addition, the thermosetting resin in the insulating sheet and the metal paste is thermoset by heating and pressurizing them. As a result, the first wiring conductor 3a in which the chemically roughened rough surface and the side surface are embedded is disposed on the surface of the insulating substrate 2 on which the plurality of insulating layers 1 are laminated, and the insulating layer. Thus, the wiring board shown in the first embodiment for carrying out the present invention in which the second wiring conductor 3b whose surface is chemically roughened between the finely roughened surface and the side surface 1 is provided. In addition, in the heat treatment of the laminate, the laminate is sandwiched between 1 and 5 MPa from above and below with a releasable sheet made of a fluororesin or the like, and heat-treated at a temperature of 150 to 240 ° C. It is preferable to thermoset the thermosetting resin in the metal paste.

  Next, a second embodiment for carrying out the present invention will be described with reference to FIGS. In these drawings, 11 is an insulating layer, 12 is an insulating substrate, 13a is a first wiring conductor made of a metal foil disposed on the surface of the insulating substrate 12, and 13b is a metal disposed between the insulating layers 11. A second wiring conductor made of foil, 14 is a through conductor, 15 is a resin layer, 16 is a third wiring conductor made of a plated metal layer, and a plurality of insulating layers 11 are laminated and integrated to form an insulating substrate 12. The second wiring conductor 13b is disposed between the first wiring conductor 13a and the insulating layer 11 on the surface of the insulating substrate 12, and the upper and lower wiring conductors 13a and 13b penetrate the insulating layer 11. The third wiring conductor 16 made of the resin layer 15 and the plated metal layer is laminated on the surface of the insulating substrate 12 and the present invention is carried out. For the first Wiring board of embodiment is constituted. In this example, the solder resistant resin layer 17 is attached to the surface of the outermost resin layer 15.

  Each insulating layer 11 constituting the insulating substrate 12 is formed by the same material and method as the insulating layer 1 in the first embodiment described above, and each of the first wiring conductor 13a and the second wiring conductor 13a each made of a metal foil. The wiring conductor 13b is supported and has a function of maintaining electrical insulation between the first wiring conductor 13a and the second wiring conductor 13b positioned above and below and between the second wiring conductors 13b.

  The first wiring conductor 13a disposed on the surface of the insulating substrate 12 and the second wiring conductor 13b disposed between the insulating layers 11 are each the first wiring conductor in the first embodiment described above. 3a, a conductive path formed of the same material and method as the second wiring conductor 3b and electrically connecting each electrode of the semiconductor element 18 mounted on the wiring board to the wiring conductor of the external electric circuit board. It functions as a part. These wiring conductors 13a and 13b include a signal conductor having a width of about 20 to 200 μm and a large-area ground or power supply conductor. Generally, fine high-density wiring is applied on the surface of the insulating substrate 12. Has been.

  In the second embodiment, the first wiring conductor 13a disposed on the surface of the insulating substrate 12 is manufactured by sticking a fine rough surface of a metal foil on a transfer film. The rough surface and side surfaces are chemically roughened, and the rough surface side is embedded in the surface of the outermost insulating layer 11. On the other hand, the 2nd wiring conductor 13b arrange | positioned between the insulating layers 11 is manufactured by sticking the rough surface of metal foil on a transfer film, and a fine rough surface and a side surface are chemically roughened. The fine rough surface side is embedded in the surface of the insulating layer 11. This is important in the second embodiment.

  The first wiring conductor 13 a disposed on the surface of the insulating substrate 12 has a rough surface and side surfaces that are chemically roughened, and the rough surface side is embedded in the surface of the insulating layer 11. The roughened rough surface and the irregularities on the side surface and the thermosetting resin of the insulating layer 11 mesh with each other and firmly adhere to the insulating layer 11, and the surface exposed to the surface of the insulating substrate 12 becomes a fine rough surface. Therefore, large unevenness is not formed on the exposed surface. Therefore, the 1st wiring conductor 13a and the 3rd wiring conductor 16 which consists of a metal plating layer mentioned later are connected favorably.

  The second wiring conductor 13b disposed between the insulating layers 11 has a rough surface and side surfaces that are chemically roughened, and the fine surface side is embedded in the surface of the insulating layer 11. Therefore, the thermosetting resin of the insulating layer 11 on the side where the second wiring conductor 13b is embedded and the finely roughened surface and side surface unevenness of the second wiring conductor 13b mesh with each other to be strong. And the unevenness of the rough surface on the opposite side meshes with the thermosetting resin of the insulating layer 11 in contact therewith and firmly adheres to the upper and lower insulating layers 11.

  Therefore, according to the wiring board of the second embodiment for carrying out the present invention, even when heat is applied when mounting the semiconductor element 18 or heat generated when the semiconductor element 18 is activated, the wiring conductor 13a or It is possible to provide a wiring board in which no peeling occurs between 13b and the insulating layer 11, and the electrical connection reliability between the first wiring conductor 13a and the third wiring conductor 16 is excellent.

  The first wiring conductor 13a disposed on the surface of the insulating substrate 12 has weak adhesion to the insulating layer 11 when the arithmetic average roughness of the chemically roughened rough surface is less than 1 μm. When heat or stress is applied to the first wiring conductor 13a, the risk of peeling from the insulating substrate 12 increases. On the other hand, when the thickness exceeds 2 μm, the first wiring conductor 13a is formed. It becomes difficult to satisfactorily form a fine wiring pattern. Therefore, the arithmetic mean roughness of the chemically roughened rough surface of the first wiring conductor 13a embedded in the surface of the insulating substrate 12 is preferably 1 to 2 μm.

  Furthermore, if the arithmetic average roughness of the chemically roughened side surface of the first wiring conductor 13a is less than 0.3 μm, it is difficult to improve the bonding force between the side surface and the insulating layer 11. If the thickness exceeds 0.7 μm, it is difficult to satisfactorily form a fine wiring pattern when forming the first wiring conductor 13a. Therefore, it is preferable that the first wiring conductor 13 a disposed on the surface of the insulating substrate 12 has an arithmetic average roughness of 0.3 to 0.7 μm on the chemically roughened side surface.

  Furthermore, the second wiring conductor 13b disposed between the insulating layers 11 has a chemically roughened fine rough surface and an arithmetic mean roughness of the side surface of less than 0.3 μm. 11 is small, and there is a high risk of peeling from the insulating layer 11. When the thickness exceeds 0.7 μm, a fine wiring pattern is formed when the second wiring conductor 13b is formed. It becomes difficult. Therefore, the second wiring conductor 13b disposed between the insulating layers 11 has an arithmetic average roughness of 0.3 to 0.7 μm on the chemically roughened fine surface and side surface. preferable. In addition, the second wiring conductor 13b disposed between the insulating layers 11 has a small adhesive force with the insulating layer 11 when the arithmetic average roughness of the rough surface thereof is less than 1 μm. When the thickness exceeds 2 μm, it is difficult to form a fine wiring pattern when forming the second wiring conductor 13b. Therefore, it is preferable that the arithmetic mean roughness of the rough surface of the second wiring conductor 13b disposed between the insulating layers 11 is 1 to 2 μm.

  Further, the through conductor 14 provided through the insulating layer 11 is formed by the same material and method as the through conductor 4 in the first embodiment described above, and the alloy powders contained in the through conductor 14 are mutually connected. The contact between the alloy powder and the copper foil constituting the wiring conductors 13a and 13b makes electrical contact between the first wiring conductor 13a and the second wiring conductor 13b and between the second wiring conductors 13b. Connect.

  Furthermore, a resin layer 15 having an opening that exposes a part of the first wiring conductor 13a is laminated on the surface of the insulating substrate 12, and the first wiring conductor is formed on the surface of the resin layer 15 and in the opening. A third wiring conductor 16 made of a plated metal layer such as copper plating electrically connected to 13a is deposited.

  The resin layer 15 has a function as a support for the third wiring conductor 16, has a thickness of 10 to 80 μm, and is a silica having an average particle diameter of 0.1 to 2 μm in a thermosetting resin such as an epoxy resin. And an insulating resin material in which an inorganic insulating filler such as alumina is dispersed at about 10 to 50% by mass.

  This resin layer 15 is formed by sticking a resin sheet formed into a sheet shape by dispersing an inorganic insulating filler having an average particle diameter of 0.1 to 2 μm in an uncured thermosetting resin on the surface of the insulating substrate 12 by a vacuum press. Then, the thermosetting resin in the resin sheet is laminated on the surface of the insulating substrate 12 by thermosetting at 150 to 200 ° C. The opening is formed by applying laser processing to the resin layer 15. When the surface of the insulating substrate 12 is roughened by, for example, a mechanical polishing method using buffol so that the arithmetic average roughness is 0.1 to 2 μm, the insulating substrate 12 and the resin layer 15 are firmly adhered to each other. Can be made. Therefore, the surface of the insulating substrate 12 is preferably roughened so that its arithmetic average roughness is 0.1 to 2 μm. In addition, the first wiring conductor 13a has a first wiring conductor that has a surface that is in contact with the resin layer 15 that is chemically roughened so that the arithmetic average roughness is 0.1 to 2 μm. 13a and the resin layer 15 in contact therewith can be firmly adhered. Therefore, the surface of the first wiring conductor 13a that is in contact with the resin layer 15 is preferably a finely roughened surface that is chemically roughened so that its arithmetic average roughness is 0.3 to 0.7 μm.

  The wiring conductor 16 deposited on the surface of the resin layer 15 and in the opening includes an electroless copper plating having a thickness of 1 to 2 μm as a base, and an electrolytic copper plating having a thickness of 10 to 30 μm as a main conductor thereon. And has a function of connecting each electrode of the semiconductor element 18 mounted on the wiring board and the first wiring conductor 13a on the surface of the insulating substrate 12 with high density. For example, a semiconductor element connection pad in which a part of the third wiring conductor 16 disposed on the outermost resin layer 15 on the upper surface side is electrically connected to the electrode of the semiconductor element 18 via the solder bump 19a. A part of the third wiring conductor 16 disposed on the outermost resin layer 15 on the lower surface side is electrically connected to the wiring conductor of the external electric circuit board via the solder bumps 19b. Forming external connection pads.

The third wiring conductor 16 is formed by a semi-additive method. Specifically, first, the surface of the resin layer 15 and the inner wall of the opening are immersed in a roughening solution such as a permanganate aqueous solution, and the surface is chemically treated so that the arithmetic average roughness becomes 0.2 to 1.0 μm. To roughen. The resin layer 15 and the third wiring conductor 16 are firmly adhered by chemically roughening the surface of the resin layer 15 and the inner wall of the opening so that the arithmetic average roughness is 0.2 to 1.0 μm. Can be made. Therefore, it is preferable to chemically roughen the surface of the resin layer 15 and the inner wall of the opening so that the arithmetic average roughness is 0.2 to 1.0 μm. Next, the surface of the first wiring conductor 13a exposed from the opening is microetched to smooth the arithmetic average roughness to 0.05 to 0.1 μm. The surface of the first wiring conductor 13a exposed from the opening is smoothed by microetching so that the arithmetic average roughness is 0.05 to 0.1 μm, whereby the first wiring conductor 13a and the third wiring conductor. 16 can be firmly attached to each other. Therefore, it is preferable to smooth the surface of the first wiring conductor 13a exposed from the opening of the resin layer 15 by microetching so that the arithmetic average roughness is 0.05 to 0.1 μm. Then, it is immersed in the aqueous solution of the palladium catalyst for electroless plating, and a palladium catalyst is made to adhere in the surface of the resin layer 15, and an opening part. Next, it is immersed in an electroless copper plating solution containing copper sulfate, formalin, EDTA sodium salt, and a stabilizer for about 30 minutes, and a thickness of about 1 to 2 μm is formed on the surface of the resin layer 15 and the entire surface of the opening. Electrolytic copper plating is deposited. Next, a plating resist layer having an opening corresponding to the wiring pattern shape of the third wiring conductor 16 is applied to the surface of the resin layer 15 and the surface of the electroless copper plating applied to the entire surface of the opening. Next, from the opening of the plating resist layer by immersing in an electrolytic copper plating solution containing sulfuric acid, copper sulfate pentahydrate, chlorine, and a brightener for several hours while applying a current of several A / dm ^2. An electrolytic copper plating having a thickness of 10 to 30 μm is deposited on the exposed electroless copper plating. Thereafter, the plating resist layer is stripped with sodium hydroxide, and the electroless copper plating exposed by stripping the plating resist layer is removed by etching with a sulfuric acid-based aqueous solution such as a mixture of sulfuric acid and hydrogen peroxide. The wiring conductor 16 is formed.

  Furthermore, in this second embodiment, a solder-resistant resin layer 17 is deposited on the outermost resin layer 15. The solder-resistant resin layer 17 has a thickness of 10 to 50 μm. For example, 30 to 70% by mass of an inorganic powder filler such as silica or talc in a mixture of a photosensitive resin such as an acrylic-modified epoxy resin and a photoinitiator. A function of preventing the adjacent third wiring conductors 16 from being electrically short-circuited by solder and improving the bonding strength between the third wiring conductor 16 and the resin layer 15. Have

  The solder-resistant resin layer 17 is formed by depositing an uncured resin film made of a photosensitive resin, a photoinitiator, and an inorganic powder filler on the surface of the outermost resin layer 15 or by using a photosensitive resin and a photoinitiator. An uncured resin varnish composed of a material and an inorganic powder filler is applied to the surface of the outermost resin layer 15 to form an uncured photosensitive resin layer, and then the uncured photosensitive resin layer is exposed. And it develops, forms an opening part, and forms this by carrying out ultraviolet curing and thermosetting.

  The wiring board of this example becomes a semiconductor device by electrically connecting each electrode of the semiconductor element 18 to the semiconductor element connection pad exposed on the upper surface side, and the external connection pad in this semiconductor device is connected to the external electric circuit board. By electrically connecting to the wiring conductor, the mounted semiconductor element 18 is connected to an external electric circuit.

  It should be noted that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the present invention.

  In order to evaluate the adhesion between the wiring conductor and the insulating layer in the wiring board of the present invention, the following samples for evaluation were manufactured and evaluated.

  First, several types of electrolytic copper foils having a rough surface and a fine rough surface and different arithmetic average roughness of the rough surface were prepared. Next, the copper foil is bonded to the transfer film and the copper foil is etched into a wiring pattern having a width of 30 to 100 μm, and then the exposed rough surface and side surfaces are chemically sprayed with formic acid. A first wiring conductor for roughening and disposing on the surface of the insulating substrate was formed on the transfer film. Also, after bonding the rough surface side of the copper foil similar to the above to the transfer film and etching the copper foil into a pattern having a width of 30 to 100 μm in the same manner as described above, the exposed fine rough surface and side surfaces are By roughening in the same manner, a second wiring conductor to be disposed between the insulating layers was formed on the transfer film.

  Next, the wiring conductor on the transfer film was embedded in the surface of the insulating sheet impregnated with uncured allyl-modified polyphenylene ether resin in a glass cloth, respectively, and then the wiring conductor was removed by removing the transfer film. Was transcribed.

  Next, the insulating sheet on which the first wiring conductor to be disposed on the surface of the insulating substrate is transferred and the insulating sheet on which the second wiring conductor to be disposed between the insulating layers are transferred are overlapped. The insulating substrate in which the first wiring conductor was disposed on the surface of the insulating substrate and the second wiring conductor was disposed between the insulating layers was obtained by hot pressing.

  Next, a resin layer made of an epoxy resin having an opening that exposes a part of the wiring conductor made of copper foil is laminated on the surface of these insulating substrates, and the surface of the wiring conductor made of copper foil exposed in the opening is micronized. After etching and smoothing so that the arithmetic average roughness becomes 0.05 to 0.1 μm, a wiring conductor made of copper plating is deposited on the surface and openings of the resin layer using a semi-additive method. A sample according to the invention was obtained. Also, for comparison outside the scope of the present invention, it was produced by the same method as described above except that the exposed surface of the electrolytic copper foil etched into the wiring pattern on the transfer film was transferred without roughening. Samples were obtained. In these samples, the wiring conductor made of copper foil and the wiring conductor made of copper plating were firmly adhered, and the electrical connection between them was good.

  Next, after these samples were put into a temperature cycle test of −55 to + 125 ° C. specified in Condition B of MIL-STD-883D for 1000 cycles, it was confirmed whether or not peeling occurred between the insulating layer and the wiring conductor. did. The quality of the pattern shape of each wiring conductor was also confirmed.

The results are shown in Table 1. In Table 1, the sample of sample number * 1 is a sample for comparison outside the scope of the present invention.

  As shown in Table 1, in the samples according to the present invention (sample numbers 2 to 5), it can be seen that the two are firmly adhered without separation between the wiring conductor and the insulating layer. On the other hand, in the sample for comparison (sample number * 1) outside the scope of the present invention, peeling occurred between the wiring conductor and the insulating layer.

  Further, among the samples according to the present invention (sample numbers 2 to 5), the arithmetic average roughness of the rough surface and the side surface of the first wiring conductor is 2.5 μm and 1.0 μm, respectively, and the second wiring conductor The sample of Sample No. 5 in which the arithmetic surface roughness of the fine rough surface and the side surface is 1.0 μm is not suitable for high-density wiring because the pattern shape of the first and second wiring conductors is bad. Arithmetic average roughness of the rough surface and side surface of the wiring conductor of 1.0 to 2.0 μm and 0.3 to 0.7 μm, respectively, and arithmetic average roughness of the fine rough surface and side surface of the second wiring conductor It can be seen that samples Nos. 2 to 3 having a thickness of 0.3 to 0.7 μm have good pattern shapes of the first and second wiring conductors, and high-density wiring is possible.

It is sectional drawing which shows the 1st example of an embodiment for implementing this invention. It is a principal part expanded sectional view of the form example shown in FIG. It is sectional drawing which shows the 2nd example for implementing this invention. It is a principal part expanded sectional view of the form example shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,11: Insulating layer 2, 12: Insulating substrate 3a, 13a: 1st wiring conductor 3b, 13b: 2nd wiring conductor 16: 3rd wiring conductor 5, 15: Resin layer

Claims (2)

An insulating substrate formed by laminating a plurality of insulating layers impregnated with a thermosetting resin ;
A metal foil having a rough surface on one side and a rough surface on the other side is patterned and embedded in the surface of the insulating layer. The first foil is disposed on the surface of the insulating substrate. A wiring conductor ;
A metal foil having a rough surface on one side and a rough surface on the other side is patterned and embedded in the surface of the insulating layer, and disposed between the insulating layers of the insulating substrate. A second wiring conductor , and a wiring board comprising:
In the first wiring conductor, the rough surface and the side surface are chemically roughened, and the rough surface side is embedded in the surface of the outermost insulating layer,
In the second wiring conductor, the fine rough surface and side surfaces are chemically roughened, and the fine rough surface side is embedded in the surface of the insulating layer,
The insulating substrate, a resin layer having an opening exposing a portion of the first wiring conductor is laminated on the surface,
The main surface of the first wiring conductor in contact with the resin layer is the finely roughened surface chemically roughened to an arithmetic average roughness of 0.3 to 0.7 μm, and the first wiring conductor The surface exposed from the opening is smoothed to an arithmetic average roughness of 0.05 to 0.1 μm by etching, and a plated metal layer or solder is deposited on the smoothed surface. Wiring board. 2. The semiconductor device according to claim 1, wherein an electrode of a semiconductor element is electrically connected to a portion exposed from the opening of the first wiring conductor of the wiring board according to claim 1.

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