JP2003110241A - Wiring board and electronic device using the same - Google Patents

Abstract

(57) [Problem] To provide a wiring board and an electronic device capable of filling a through hole with a copper conductor satisfactorily, having excellent smoothness on the surface of the through conductor, and securely and firmly connecting electronic components. SOLUTION: A plurality of insulating layers 1 and wiring conductors 2 are alternately laminated, and a through hole formed between upper and lower wiring conductors 2 by filling a through hole 3 formed in the insulating layer 1 with a copper conductor formed by electrolytic plating. In the wiring board 5 electrically connected by the conductor 4, the copper conductor has a current density of 0.3 to 0.8 A / dm.
^A first layer 4a occupying a thickness of 2/3 to 3/4 by electrolytic plating 2 and a second layer 4b occupying the remaining thickness by electrolytic plating having a current density of 1.0 to 3.0 A / dm ² ; The crystal grain size on the surface of the second layer 4b is 0.1 to 2 μm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wiring board for accommodating electronic parts such as semiconductor integrated circuit elements and an electronic device using the same.

[0002]

2. Description of the Related Art Generally, current electronic devices are required to be small, thin, lightweight, high-performance, high-performance, high-quality and highly reliable as represented by mobile communication devices. Electronic devices mounted on various electronic devices are also required to be small and have high density. Therefore, wiring boards that make up electronic devices are also required to be small, thin, and have multiple terminals. To achieve this, the widths of wiring conductors such as signal conductors are made narrower and the intervals between them are reduced. High-density wiring is achieved by multilayering wiring conductors.

A wiring board manufactured by adopting a build-up method is known as a wiring board capable of such high-density wiring. The build-up method is, for example, a wiring conductor on a core body obtained by impregnating a reinforcing material such as glass cloth or aramid non-woven fabric with a thermosetting resin typified by an epoxy resin having heat resistance and chemical resistance and curing the same. After depositing and forming the insulating layer on the wiring conductor by applying a varnish made of a thermosetting resin such as an epoxy resin on the core body including the wiring conductor and heating and curing it. Laser diameter
A through hole of about 50 to 200 μm is bored, and then a copper conductor film is deposited on the surface of the insulating layer and a copper conductor film is deposited and filled inside the through hole to form a wiring conductor and a through conductor. A method of manufacturing a wiring board in which the formation of an insulating layer and a through conductor / wiring conductor is repeated a plurality of times thereon.

As a method for forming such a wiring conductor and a through conductor, there are a semi-additive method in which electroless plating and electrolytic plating are combined, and a full additive method only with electroless plating. However, since the full-additive method forms the wiring conductor and the through conductor only by electroless plating, it takes a long time to form the wiring conductor and the through conductor, and thus has a problem of poor productivity. ing. Therefore, the wiring conductor and the through conductor are generally formed by using a semi-additive method that combines electroless plating and electrolytic plating.

In such a semi-additive method, an electroless copper plating layer having a thickness of 1 to 2 μm is deposited on the surface of the insulating layer and the inside of the through hole, and an opening corresponding to the wiring pattern is formed thereon by a dry film resist. While forming a plating resist layer having, the electrolytic copper plating layer is formed by depositing on the electroless copper plating layer exposed from the opening, and then the plating resist layer is peeled off, and then the electrolytic copper plating layer and plating are performed. This is a method of forming a wiring conductor and a through conductor by etching the electroless copper plating layer exposed on the surface by peeling the resist layer.

In the wiring board manufactured by the build-up method, a part of the wiring conductor on the surface is formed as a mounting electrode for mounting an electronic component, and the mounting electrode and the electronic component are connected via solder bumps. Is connected to the terminal.
In addition, a nickel-gold plating layer having excellent adhesion to the solder bumps is deposited on the surface of the mounting electrode.

[0007]

However, according to the above wiring board, when the through-hole is filled with the electrolytic copper plating layer, if the electrolytic copper plating layer is formed at a high current density of 1.0 A / dm ² or more, The growth of the electrolytic copper plating layer in the vicinity of the opening of the through hole is greatly promoted as compared with the growth of the electrolytic copper plating layer in the inside of the through hole. The copper plating layer first closes the opening of the through hole to form a cavity inside the through conductor, and the heat inside the electronic component mounted on the wiring board blocked the cavity inside the through conductor. The liquid expands rapidly,
There is a problem in that the wiring board swells and the electronic component cannot be reliably mounted.

Further, according to the above wiring board, when the thickness of the insulating layer is larger than the diameter of the through hole, the electrolytic copper plating solution hardly penetrates into the through hole, and the electrolytic copper plating layer is well formed in the through hole. However, there is also a problem in that it becomes impossible to adhere and fill.

Further, according to the above wiring board, 0.8 A
When the electrolytic copper plating layer is formed at a low current density of / dm ² or less, the deposition of the electrolytic copper plating layer in the through holes is good, but the plating time is long and not only the productivity decreases, but also The crystal grain size of the electrolytic copper plating layer becomes large, and granular projections of 2 to 10 μm are formed on the surface of the electrolytic copper plating layer after etching. As a result, nickel-gold formed on the surface of the mounting electrode of the wiring board. There is a problem that the thickness of the plating layer becomes non-uniform, the connection strength between the mounting electrode and the solder bump is reduced, and the electronic component cannot be firmly connected to the wiring board.

The present invention has been completed in view of the above problems of the prior art, and its purpose is to be able to satisfactorily fill a through hole with a copper conductor, to provide an excellent smoothness of the surface of the through conductor, and to ensure that an electronic component can be manufactured. An object of the present invention is to provide a wiring board that can be firmly connected and an electronic device using the same.

[0011]

In the wiring board of the present invention, a plurality of insulating layers and wiring conductors are alternately laminated and a through hole formed between the upper and lower wiring conductors in the insulating layer is formed by electrolytic plating. In a wiring board electrically connected by a through conductor formed by filling with a conductor, the copper conductor has a current density of 0.3 to 0.8 A / dm ² and is 2/3 to ³ by electrolytic plating.
The first layer occupying a thickness of / 4 and the current density is 1.0 to 3.0 A /
The second layer occupies the remaining thickness of the dm ² electrolytic plating, and the crystal grain size of the surface of the second layer is 0.1 to 2
It is characterized by being μm.

Further, the wiring board of the present invention is characterized in that, in the above-mentioned constitution, the thickness of the insulating layer is 15 to 50 μm and the diameter of the through hole is 30 to 200 μm.

The electronic device of the present invention is characterized in that an electronic component is mounted on the surface of the above-mentioned wiring board, and an electrode of the electronic component is electrically connected to a wiring conductor or a through conductor. .

According to the wiring board of the present invention, the copper conductor forming the penetrating conductor is electrolytically plated at a current density of 0.3 to 0.8 A / dm ² , and the first layer occupies a thickness of 2/3 to 3/4; The formation of the copper conductor was made from the second layer occupying the remaining thickness of the electrolytic plating having a current density of 1.0 to 3.0 A / dm ² and the crystal grain size of the surface of the second layer was 0.1 to 2 μm. Can be performed in a short time, a wiring board with excellent productivity can be obtained, and a nickel-gold plating layer can be uniformly formed on the surface of the second layer, so that the connection strength with solder bumps can be improved. Therefore, it is possible to provide a wiring board which has a high cost and can be firmly connected to the mounted electronic components.

Further, according to the wiring board of the present invention, in the above structure, the thickness of the insulating layer is set to 15 to 50 μm, and the diameter of the through hole is set to 30 to 200 μm. Can be easily penetrated into the through hole, and the electrolytic copper plating layer can be well deposited and filled in the through hole. As a result, a cavity is not formed inside the through conductor and the electronic component is mounted on the wiring board. The wiring board does not bulge due to the heat generated during the process.

According to the electronic device of the present invention, the electronic component is mounted on the surface of the wiring board, and the electrode of the electronic component is electrically connected to the wiring conductor or the through conductor. An electronic device having a strong connection with the wiring board can be provided.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a wiring board of the present invention and an electronic device using the same will be described in detail with reference to the accompanying drawings. 1 is a sectional view showing an example of an embodiment of a wiring board of the present invention and an electronic device using the same.
FIG. 2 is an enlarged cross-sectional view of the main part of FIG.

In these figures, 1 is an insulating layer, 2 is a wiring conductor, 3 is a through hole, and 4 is a through conductor, and these mainly constitute the wiring board 5 of the present invention. In addition, an electronic component 6 such as a semiconductor element is mounted on the mounting electrode 2a formed of a part of the wiring conductor 2.
The electronic device 7 of the present invention is manufactured by mounting the.

The wiring board 5 has a function of mounting the electronic component 6, and is, for example, a plate-shape formed by impregnating a glass cloth in which glass fibers are woven vertically and horizontally with a thermosetting resin such as epoxy resin or bismaleimide triazine resin. Core insulation layer 1a
It is a multi-layer board in which a plurality of insulating layers 1b made of a thermosetting resin such as an epoxy resin or a modified polyphenylene ether resin and a wiring conductor 2 made of a copper plating film are alternately laminated on the upper and lower surfaces.

The core insulating layer 1a has a function of giving strength to the wiring board 5, has a thickness of 0.3 to 1.5 mm, and has a plurality of through holes 9 having a diameter of 0.1 to 1.0 mm from its upper surface to its lower surface. Have A copper plating film is deposited on the inner wall of each through hole 9, and the wiring conductor layers 8 formed on the upper and lower surfaces are electrically connected via the copper plating film of the through hole 9.

Such a core insulating layer 1a is manufactured by thermosetting a sheet in which glass cloth is impregnated with an uncured thermosetting resin, and then drilling the sheet from the upper surface to the lower surface. . For the wiring conductor layers 8 on the upper and lower surfaces of the core insulating layer 1a, a copper film having a thickness of 3 to 50 μm is deposited on the entire upper and lower surfaces of the sheet for the core insulating layer 1a, and the copper film is cured. After that, it is formed into a predetermined pattern by etching. Also, through hole 9
The copper plating film on the inner wall has a through hole 9 in the core insulating layer 1a.
Is formed, and then a copper plating film having a thickness of about 3 to 50 μm is deposited in the through hole 9 by a plating method. The wiring conductor layer 8 has through holes 9
When the copper plating film is formed on the inner wall, it may be simultaneously formed by a plating method.

Further, in the core insulating layer 1a, resin columns 10 made of a thermosetting resin such as epoxy resin or bismaleimide triazine resin are filled in the through holes 9. The resin pillar 10 is for closing the through hole 9 so that the insulating layer 1b can be formed directly above and directly below the through hole 9, and an uncured paste-like thermosetting resin is placed in the through hole 9. It is formed by filling by a screen printing method, thermally curing it, and polishing the upper and lower surfaces thereof to be substantially flat. The insulating layer 1b and the wiring conductor 2 are laminated on the upper and lower surfaces of the core insulating layer 1a including the resin columns 10.

The insulating layer 1b is provided to provide an insulating space for wiring the wiring conductors 2 at high density. Then, high-density wiring can be three-dimensionally formed by electrically connecting the wiring conductors 2 located above and below through the penetrating conductor 4 made of a copper conductor formed inside the through hole 3.

The insulating layer 1b is made of a thermosetting resin such as an epoxy resin, a bismaleimide triazine resin or a modified polyphenylene ether resin, and an inorganic filler such as silica, and has a coefficient of thermal expansion in the thickness direction of the insulating layer 1b. 20 ~
It is preferably set at 60 × 10 ⁻⁶ / ° C. Incidentally, the thermal expansion coefficient is less than 20 × 10 ^-6 / ℃, tend to crack becomes hard and brittle insulating layer 1b is is likely to occur, 60 × 10 ^-6
If the temperature exceeds / ° C, the through conductor 4 and the insulating layer 1
b tends to peel off easily. Further, in order to set the thermal expansion coefficient of the insulating layer 1b to 20 to 60 × 10 ⁻⁶ / ° C., 50 to 80% by weight of an inorganic filler such as silica may be filled in the thermosetting resin.

Then, such a wiring board 5 is manufactured by the following steps. First, a film made of a thermosetting resin and an inorganic filler is laminated on the surfaces of the core insulating layer 1a and the wiring conductor layer 8 and thermoset to form the first insulating layer 1b. Next, a through hole 4 is formed in the insulating layer 1b on the wiring conductor layer 8 by a laser, and then the insulating layer 1b and the inside of the through hole 3 are immersed in a roughening solution such as a permanganate aqueous solution to roughen. . Next, the insulating layer 1b and the through hole 3
After depositing an electroless plating catalyst such as palladium on the inside, the wiring board 5 is covered with copper sulfate, Rossell salt, formalin, E
It is dipped in an electroless plating solution containing DTA sodium salt / stabilizer for about 30 minutes to deposit 1-2 μm of electroless copper plating on the surface of the insulating layer 1b and inside the through holes 3. And
The electroless copper plating on the insulating layer 1b is covered with a plating resistant resin layer, and an opening to be a wiring pattern is formed in the plating resistant resin layer by exposure and development. Further, the wiring board 5 is immersed in an electrolytic copper plating solution containing sulfuric acid, copper sulfate pentahydrate, chlorine, a brightener, etc., and electrolytic copper plating is performed at a current density of 0.3 to 0.8 A / dm ² for several minutes to penetrate the wiring board 5. The first layer 4a of the copper conductor forming the through conductor 4 is formed to a thickness of 2/3 to 3/4 in the depth direction of the hole 3, and then electrolysis is performed for several minutes at a current density of 1.0 to 3.0 A / dm ^2. The second layer 4b of the copper conductor is formed by copper plating, and the through hole 3 is filled with the copper conductor. At this time, the electrolytic copper plating layer is also deposited on the opening of the anti-plating resin layer which becomes the wiring conductor 2 on the surface of the insulating layer 1b. Thereafter, the plating resistant resin layer is peeled off, and the electroless plating under the plating resistant resin layer is removed by etching to form the wiring conductor 2. After that, the wiring board 5 is manufactured by repeatedly forming the second and subsequent insulating layers 1b and the penetrating conductors 4 and the wiring conductors 2 in the same manner as described above.

Here, the thickness of the copper conductor filling the through hole 3 refers to the thickness corresponding to the substantial depth of the through hole 3 as shown in FIG. In addition, the thickness of the first layer 4a of the copper conductor refers to the thickness from the lower surface of the first layer 4a to the lowest portion of the upper surface thereof, as shown by X in FIG.
The thickness b is the thickness obtained by subtracting the thickness X of the first layer 4a of the copper conductor from the thickness A of the copper conductor as shown in Y of FIG.

Further, the thickness of the first layer 4a of the copper conductor is preferably set to 2/3 to 3/4 of the thickness of the copper conductor in the depth direction of the through hole 3. If the thickness is less than 2/3, 1.0-
The number of copper conductors formed at a high current density of 3.0 A / dm ² increases, and the vicinity of the opening of the through hole 3 is closed first and the through conductor 4
There is a tendency that a cavity is easily formed in the central part of the above, and if the thickness exceeds 3/4, the electrolytic plating time becomes longer and the productivity tends to decrease. Therefore, the thickness of the first layer 4a is
It is preferable that the depth of the through hole 3 is set to 2/3 to 3/4 of that of the copper conductor.

The current density of the electroplating for forming the first layer 4a is preferably 0.3 to 0.8 A / dm ² , and 0.3 A / dm 2.
^If it is less than ^2, it takes a long time to deposit the electrolytic plating and the productivity tends to decrease, and if it exceeds 0.8 A / dm ² , the vicinity of the opening of the through hole 3 is closed first and the center of the through conductor 4 is closed. There is a tendency that a cavity is easily formed in the part. Therefore, the current density of the electroplating of the first layer 4a is preferably 0.3 to 0.8 A / dm ² .

Further, the current density of the electrolytic plating forming the second layer 4b is preferably 1.0 to 3.0 A / dm ² , and 1.0 A / d.
If it is less than m ² , the crystal grain size of the electrolytic copper plating layer tends to be large, and granular projections of 2 to 10 μm tend to be formed on the surface of the electrolytic copper plating layer, which exceeds 3.0 A / dm ² . And the growth rate of electrolytic copper plating tends to be too fast, making it difficult to control the thickness. Therefore, it is preferable that the current density of electrolytic plating of the second layer 4b is 1.0 to 3.0 A / dm ² .

The thickness of the insulating layer 1b is preferably 15 to 50 μm, and if the thickness is less than 15 μm, the insulating property of the insulating layer 1b tends to deteriorate, and if it exceeds 50 μm, the through hole 3 becomes deep. It becomes difficult for the plating solution to penetrate,
It tends to be difficult to fill the through holes 3 with the through conductors 4 formed by electrolytic copper plating. Therefore, the thickness of the insulating layer 1b is preferably 15 to 50 μm. Further, the diameter of the through hole 3 formed in the insulating layer 1b is preferably 30 to 200 μm, and if the diameter is less than 30 μm, it is difficult for the plating solution to penetrate, and the through hole 3 is a through conductor formed by electrolytic copper plating. 4 tends to be difficult to fill, and if it exceeds 200 μm, high-density wiring tends to be difficult. Therefore, the diameter of the through hole 3 is preferably 30 to 200 μm.

The wiring conductor 2 has a function as a conductive path for connecting each electrode of the electronic component 6 such as a semiconductor element to be mounted to an external electric circuit board (not shown), and a high-speed signal is transmitted. Is preferably 5 μm or more from the viewpoint of transmitting the heat conductivity, and is preferably 50 μm or less from the viewpoint of preventing peeling due to a difference in thermal expansion between the wiring conductor 2 and the insulating layer 1b. Therefore, the thickness of the wiring conductor 2 is 5
It is preferable that the thickness is -50 μm.

Further, the wiring board 5 of the present invention includes the through conductor 4
It is important that the crystal grain size of the second layer 4b is 0.1 to 2 μm. If the crystal grain size is less than 0.1 μm, it tends to be easily etched, and it is difficult to control the thickness. If it exceeds 2 μm, the electrolytic copper plating layer surface has 2 to 10 μm.
When the nickel-gold plated layer is formed on the surface of the mounting electrode 2a of the wiring board 5, the thickness of the nickel-gold plated layer becomes non-uniform, and the mounting electrode 2a and the electronic component are formed. There is a tendency that the bonding strength with the conductor bumps 11 that connect 6 to each other is reduced, and the electronic component 6 cannot be reliably mounted. Therefore, the crystal grain size of the second layer 4b
It is important to set the thickness to 0.1 to 2 μm. In order to set the crystal grain size to 0.1 to 2 μm, the current density for forming the second layer 4b may be set to 1.0 to 3.0 A / dm ² .

Further, a part of the wiring conductor 2 formed on the surface of one of the outermost layers of the insulating layer 1b is connected to each electrode of the electronic component 7 through the conductor bump 11 for mounting the electronic component 6 for mounting. A part of the wiring conductor 2 forming the electrode 2a and formed on the surface of the other outermost layer of the insulating layer 1b is connected to each electrode of the external electric circuit board (not shown) through the conductor bump 11. A mounting electrode 2a for external connection is formed.

The surface of the mounting electrode 2a is made of nickel-gold or the like which has good wettability with solder and excellent corrosion resistance in order to prevent its oxidation and corrosion and to make the connection of the conductor bump 11 good. The plating layer is applied.

The outermost insulating layer 1b and the mounting electrode 2a are covered with a solder-resistant resin layer 12 having an opening for exposing the central portion of the mounting electrode 2a. The solder-resistant resin layer 12 has a thickness of 10 to 50 μm. For example, 30 to 70% by weight of inorganic powder filler such as silica or talc is added to a mixture of a photosensitive resin such as an acrylic modified epoxy resin and a photoinitiator. Which is made of an insulating material, prevents the adjacent mounting electrodes 2a from being electrically short-circuited by the conductor bumps 11, and the mounting electrode 2a and the insulating layer 1b.
It has a function of improving the bonding strength with.

Such a solder-resistant resin layer 12 is formed by applying an uncured resin film composed of a photosensitive resin, a photoinitiator, and an inorganic powder filler to the surface of the outermost insulating layer 1b, or a thermosetting resin. An uncured resin varnish composed of an inorganic powder filler and an uncured resin varnish is applied to the surface of the outermost insulating layer 1b and dried, and then an opening is formed by exposure / development, which is UV-cured and heat-cured. To be done.

Thus, according to the wiring board 5 of the present invention,
The current density of the copper conductor forming the through conductor 4 is 0.3 to 0.8 A.
Formed from / to the first layer 4a occupying the thickness of 2/3 to 3/4 by electrolytic plating dm ^2, and the second layer 4b current density occupies the remaining thickness by electrolytic plating 1.0～3.0A / dm ² And the crystal grain size on the surface of the second layer 4b is 0.1 to
Since the thickness is 2 μm, the through conductor 4 reliably filled with the copper conductor can be formed without forming a cavity in the central portion of the through conductor 4, there is no swelling or peeling at the time of mounting, and the wiring conductor is A wiring board 5 capable of uniformly forming a nickel-gold plating layer on the surface of the mounting electrode 2a consisting of a part of the wiring 2 and having a high connection strength with the solder bump 11 and capable of firmly connecting with the mounted electronic component 6. can do.

According to the wiring board 5 of the present invention, the thickness of the insulating layer 1 is set to 15 μm to 50 μm and the through hole 3 is formed.
Since the diameter of the electrolytic copper plating solution is 30 to 200 μm, the electrolytic copper plating solution can easily penetrate into the through holes 3, and the inside of the through holes 3 can be completely adhered and filled with the electrolytic copper plating layer, so that the through conductors 4 have no defect wiring. It can be the substrate 5.

The conductive bumps 11 are made of a conductive material of an alloy such as lead-tin, tin-zinc, tin-silver-bismuth. For example, in the case of solder made of lead-tin, a solder paste made of lead-tin is used. Is the mounting electrode 2 in which the opening of the solder-resistant resin layer 12 is exposed.
It is filled by screen printing on a and is passed through a reflow oven to be fixedly formed in a hemispherical shape on the mounting electrode 2a. Then, each electrode of the electronic component 6 is bonded to the mounting electrode 2a through the conductor bump 11 to mount the electronic component 6, and the wiring board 5 and the electronic component 6 are adhered with the underfill material F. An electronic device 7 is obtained by sealing the electronic component 6 with a lid or potting resin (not shown), and the mounting electrodes 2a in the electronic device 7 are connected to the external electric circuit board (not shown) via the conductor bumps 11. By connecting to the wiring conductor, the electronic device 7 of the present invention is mounted on an external electric circuit board (not shown).

Thus, according to the electronic device 7 of the present invention,
Since the electronic component 6 is mounted on the surface of the wiring board 5 and the electrode of the electronic component 6 is electrically connected to the wiring conductor 2 or the through conductor 4, the crystal grain size of the electrolytic copper plating is small. The surface of the electrolytic copper plating layer after etching becomes smooth, the nickel-gold plating layer on the surface of the mounting electrode 2a of the wiring board 5 has a uniform thickness, and the mounting electrode 2a and the solder bump 11 have sufficient connection strength. Obtained, electronic component 6
The electronic device 7 can be firmly connected to the wiring board 5.

It is needless to say that the present invention is not limited to the above-mentioned example of the embodiment, and various modifications can be made without departing from the scope of the present invention.

[0042]

EXAMPLES Example 1 A film made of a thermosetting resin and an inorganic filler is used as a wiring conductor layer 8 and a core insulating layer 1a.
After being laminated on the surface and thermally cured to form an insulating layer 1b having a thickness of 30 μm, a through hole 3 having a diameter of 50 μm was formed in the insulating layer 1b on the wiring conductor layer 8 by laser. next,
The insulating layer 1b and the inside of the through-hole 3 are immersed in a roughening solution such as an aqueous solution of permanganates to be roughened, and an electroless plating catalyst such as palladium is deposited, and then copper sulfate, Rossell salt, formalin, EDTA sodium salt It was immersed in an electroless plating solution containing a stabilizer or the like for about 30 minutes to deposit 1-2 μm of electroless copper plating on the surface of the insulating layer 1b and inside the through holes 3. After that, the electroless copper plating on the insulating layer 1b is covered with a plating resistant resin layer, and an opening to be a wiring pattern is formed by exposure and development, and thereafter, it is made of sulfuric acid, copper sulfate pentahydrate, chlorine, a brightener, etc. The first layer 4a of the electroplating layer is immersed in an electrolytic copper plating solution and electrolytically plated at a current density of 0.5 A / dm ² for 30 minutes to a depth of 20 μm, which is 2/3 of the depth of the through hole 3 of 30 μm. Then, the second layer 4b having a thickness of 10 μm was formed by electrolytic plating at a current density of 1.5 A / dm ² for 10 minutes, and the through hole 3 was filled with a copper conductor. Then, the anti-plating resin layer is peeled off using a 5% sodium hydroxide aqueous solution, and then the electroless plating under the anti-plating resin layer is removed by etching using a sulfuric acid / hydrogen peroxide-based or copper chloride-based etching solution. Conductor 4 and wiring conductor 2
Was formed.

In the wiring board 5 manufactured within the above condition range of the present invention, the through hole 3 is well filled with the copper conductor and the surface of the through conductor 4 is excellent in smoothness, so that the electronic component 6 is securely and firmly connected. It was a wiring board 5 that could be formed.

(Comparative Example 1) Electrolytic copper plating was performed at 2.5 A / dm ²
It was confirmed by electron microscope observation of the cross section of the through conductor that the wiring board manufactured in the same manner as above except that the current density of 15 minutes was used, and a fine cavity was formed in the center of the through conductor. Sometimes the wiring board swelled and electronic parts could not be mounted.

The wiring board produced in the same manner as above except that the electrolytic copper plating was carried out at a current density of 0.5 A / dm ² for 60 minutes had good plating properties for the through holes, but after etching. When the surface of the copper conductor of No. 4 was confirmed with a metallurgical microscope × 400, countless minute protrusions with a diameter of about 5 μmφ and a height of 2 to 4 μm were confirmed, and the thickness of the nickel-gold plating of the mounting electrodes became uneven, The connection strength between the mounting electrode and the conductor bump was reduced to 2/3.

[0046]

According to the wiring board of the present invention, the copper conductor forming the through conductor is electrolytically plated with a current density of 0.3 to 0.8 A / dm ² and the first layer occupies a thickness of 2/3 to 3/4. When,
The formation of the copper conductor was made from the second layer occupying the remaining thickness of the electrolytic plating having a current density of 1.0 to 3.0 A / dm ² and the crystal grain size of the surface of the second layer was 0.1 to 2 μm. Can be performed in a short time, a wiring board with excellent productivity can be obtained, and a nickel-gold plating layer can be uniformly formed on the surface of the second layer, so that the connection strength with solder bumps can be improved. Therefore, it is possible to provide a wiring board which has a high cost and can be firmly connected to the mounted electronic components.

According to the wiring board of the present invention, the thickness of the insulating layer is 15 to 50 μm, and the diameter of the through hole is 30 to 50 μm.
Since the thickness is set to 200 μm, the electrolytic copper plating solution can easily penetrate into the through holes, and the deposition of the electrolytic copper plating layer into the through holes can be favorably performed. As a result, cavities are formed inside the through conductors. Therefore, the wiring board will not be swollen by the heat when the electronic component is mounted on the wiring board.

According to the electronic device of the present invention, the electronic component is mounted on the surface of the wiring board, and the electrode of the electronic component is electrically connected to the wiring conductor or the through conductor. An electronic device having a strong connection with the wiring board can be provided.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of an embodiment of an electronic device in which an electronic component is mounted on a wiring board of the present invention.

FIG. 2 is an enlarged sectional view of an essential part of the wiring board of the present invention.

[Explanation of symbols]

1 ... Insulation layer 1a .... Insulating layer of core 1b ... Insulating layer 2 ... Wiring conductor 2a ...- Mounting electrodes 3 ... through-hole 4 ... Penetration conductor 4a ... First layer of copper conductor 4b .... Second layer of copper conductor 5 ... Wiring board 6 ... Electronic parts 7 ... Electronic device A ・ ・ ・ ・ ・ ・ Copper conductor thickness X ... Thickness of the first layer of the copper conductor Y ... Thickness of second layer of copper conductor

Claims (3)

[Claims] 1. A through conductor formed by alternately stacking a plurality of insulating layers and wiring conductors and filling a through hole formed in the insulating layer between upper and lower wiring conductors with a copper conductor by electrolytic plating. In the wiring board electrically connected, the copper conductor has a current density of 0.3 to 0.8 A /
It is composed of a first layer occupying a thickness of 2/3 to 3/4 by electrolytic plating of dm ² , and a second layer occupying the remaining thickness of electrolytic plating having a current density of 1.0 to 3.0 A / dm ^2. In addition, the crystal grain size of the surface of the second layer is 0.1 to 2 μm. 2. The wiring board according to claim 1, wherein the insulating layer has a thickness of 15 to 50 μm, and the through hole has a diameter of 30 to 200 μm. 3. An electronic component is mounted on the surface of the wiring board according to claim 1 or 2, and an electrode of the electronic component is electrically connected to the wiring conductor or the through conductor. And electronic device.