JP4127377B2 - Wiring board and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a wiring board used for mounting an electronic component such as a semiconductor element and a manufacturing method thereof.
[0002]
[Prior art]
In general, current electronic devices are required to be small, thin, lightweight, high performance, high functionality, high quality, and high reliability, as represented by mobile communication devices. Electronic devices to be used are also required to be small and high density. For this reason, the wiring board constituting the electronic device is also required to be small, thin, and multi-terminal. To realize this, the width of the wiring conductor layer including the signal conductor is reduced and the interval is reduced. Further, high-density wiring is achieved by increasing the number of wiring conductor layers.
[0003]
As a wiring board capable of such high-density wiring, a wiring board manufactured by adopting a build-up method is known. This build-up wiring board is manufactured, for example, by the method described below.
[0004]
First, a wiring made of metal foil on an insulating sheet impregnated with a heat-resistant or chemical-resistant epoxy resin or a thermosetting resin typified by an allyl-modified polyphenylene ether resin on a reinforcing material such as glass cloth or aramid non-woven fabric A core substrate is obtained by embedding a conductor and then heating and curing it to embed a wiring conductor in an insulating substrate.
[0005]
Next, a resin film made of a thermosetting resin such as an epoxy resin is attached to the core substrate and cured by heating to form an insulating resin layer having a thickness of 20 to 200 μm. Next, a through hole with a diameter of 50 to 200 μm is drilled in the insulating resin layer on the wiring conductor with a laser, and the surface of the insulating resin layer and the inner surface of the through hole are chemically treated with a roughening solution such as a potassium permanganate solution. Next, using a semi-additive method, a conductor film made of copper plating is deposited on the surface of the insulating resin layer and the inner surface of the through hole using a semi-additive method to form a wiring conductor layer and a through conductor. A build-up wiring board is manufactured by repeating the formation of the insulating resin layer and the through conductor / wiring conductor layer a plurality of times.
[0006]
[Patent Document 1]
JP 2002-261451 A
[0007]
[Problems to be solved by the invention]
However, the above wiring board has a thermal expansion coefficient of 10 × 10 10 for the insulating substrate. ^-6 ~ 15 × 10 ^-6 / ℃, the thermal expansion coefficient of the wiring conductor made of copper foil is 15 × 10 ^-6 ~ 20 × 10 ^-6 Because the thermal expansion coefficient of the insulating substrate and the thermal expansion coefficient of the wiring conductor are different, the thermal expansion of the insulating substrate and the wiring conductor will occur if a long-term thermal history is repeatedly applied after mounting electronic components on the wiring substrate. The thermal stress generated by the difference is concentrated at the boundary between the insulating substrate and the wiring conductor, and a gap is generated between the side surface of the wiring conductor and the insulating substrate. There is a problem that the layer may be cut to cause disconnection failure.
[0008]
In addition, when an allyl-modified polyphenylene ether resin is used for the core substrate, the allyl-modified polyphenylene ether resin is chemically stable and difficult to roughen, and an insulating resin layer containing an epoxy resin is laminated on the surface of the core substrate. In this case, the allyl-modified polyphenylene ether resin of the core substrate and the epoxy resin of the insulating resin layer cannot be firmly bonded, and as a result, the adhesion between the core substrate and the insulating resin layer laminated thereon is weak. For example, when an electronic component is mounted on the surface of the wiring board, a rapid temperature change is applied to the wiring board, or heat generated when the electronic component is operated after mounting the electronic component or due to the external environment If heat or the like is repeatedly applied over a long period of time, swelling or peeling may occur between the insulating resin layer and the core substrate. Also it had problems.
[0009]
On the other hand, the above-described method for manufacturing a wiring board manufactures a wiring board by embedding a wiring conductor in an insulating substrate and depositing an insulating resin layer on the insulating substrate. If the adhesion with the insulating resin layer is weak and long-term thermal history is repeatedly applied after mounting electronic components on the wiring board, the thermal stress generated by the thermal expansion difference between the insulating board, the wiring conductor and the insulating resin layer is insulated. Concentrating on the boundary between the substrate and the wiring conductor and the boundary between the insulating substrate and the insulating resin layer, a gap is generated between the side surface of the wiring conductor and the insulating substrate, and a crack occurs in the insulating resin layer starting from the clearance. At the same time, the wiring conductor layer is cut to cause disconnection failure, or the insulating resin layer may be peeled off from the insulating substrate.
[0010]
The present invention has been completed in view of the problems of the prior art, and its purpose is to sufficiently withstand thermal stress even when a long-term thermal history is repeatedly applied to a wiring board on which electronic components are mounted, and the wire breaks. An object of the present invention is to provide a wiring board with high connection reliability that does not cause the above.
[0011]
[Means for Solving the Problems]
In the wiring board of the present invention, a wiring conductor made of a copper foil is embedded in an insulating board in which an allyl-modified polyphenylene ether resin is impregnated in a heat-resistant fiber base so that the surface thereof is flush with the surface of the insulating board. In the wiring board formed by alternately laminating an insulating layer containing epoxy resin and a wiring conductor layer made of copper plating on the surface of the core board embedded in the wiring board, the side surface of the wiring conductor is It is roughened and embedded in the insulating substrate with the epoxy resin interposed between the side surface and the insulating substrate.
[0012]
According to the wiring board of the present invention, the wiring conductor has a roughened side surface and is embedded in the insulating substrate with the epoxy resin interposed between the side surface and the insulating substrate. An epoxy resin interposed between the side surface and the insulating substrate serves as an adhesive, and the side surface of the wiring conductor and the epoxy resin are firmly bonded to each other so that the wiring conductor and the insulating substrate are firmly bonded. Can do. As a result, after mounting electronic components on the wiring board, a long-term thermal history is repeatedly applied to the wiring board, and thermal stress generated by the thermal expansion difference between the insulating board and the wiring conductor is generated at the boundary between the insulating board and the wiring conductor. Even if concentrated, there is no gap between the side surface of the wiring conductor and the insulating substrate, and cracks are generated in the insulating layer starting from the gap, or this crack cuts the wiring conductor layer and causes disconnection failure. It never happens.
[0013]
Further, according to the wiring board of the present invention, the insulating substrate and the insulating layer are firmly bonded by the anchor effect of the epoxy resin interposed between the side surface of the wiring conductor and the insulating substrate, and as a result, the electronic circuit is connected to the wiring substrate. Even if a long-term thermal history is repeatedly applied after mounting a component and the thermal stress generated by the difference in thermal expansion between the insulating substrate and the insulating layer is concentrated at the boundary between them, the insulating layer will be peeled off from the insulating substrate. Nor.
[0014]
The method for manufacturing a wiring board according to the present invention is such that a wiring conductor made of copper foil is formed on an insulating substrate impregnated with an allyl-modified polyphenylene ether resin on a heat-resistant fiber base so that the surface thereof is flush with the surface of the insulating substrate. A step of preparing an embedded core substrate; and the surface of the core substrate on which the wiring conductor is embedded is irradiated with plasma to shrink the surface of the core substrate and the allyl-modified polyphenylene ether resin located in the vicinity thereof Forming a gap between the side surface of the wiring conductor and the insulating substrate, roughening the side surface of the wiring conductor exposed in the gap, and the wiring conductor of the core substrate. A process of depositing an insulating layer containing an epoxy resin on the buried surface and filling the gap with the epoxy resin, and forming a copper plating on the surface of the insulating layer. The wiring conductor layer is characterized in that it comprises the step of depositing.
[0015]
According to the method for manufacturing a wiring substrate of the present invention, the surface of the core substrate on which the wiring conductor is embedded is irradiated with plasma to shrink the allyl-modified polyphenylene ether resin located on the surface of the core substrate and in the vicinity thereof. A gap is formed between the side surface of the wiring board and the insulating substrate, and then the side surface of the wiring conductor exposed in the gap is roughened, and then an insulating layer containing epoxy resin is embedded on the surface of the core board where the wiring conductor is embedded. The epoxy resin interposed between the side surface of the wiring conductor and the insulating substrate serves as an adhesive, and the side surface of the wiring conductor and the epoxy resin are strong. A wiring board in which the wiring conductor and the insulating substrate are firmly bonded can be provided. In addition, since the insulating substrate and the insulating layer are firmly bonded by the anchor effect of the epoxy resin interposed between the side surface of the wiring conductor and the insulating substrate, a wiring substrate having a strong bonding between the insulating substrate and the insulating layer is provided. can do.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Next, the wiring board of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a cross-sectional view showing an example of an embodiment of a wiring board according to the present invention, and FIG. 2 is an enlarged cross-sectional view of a main part of FIG. In these drawings, 1 is an insulating substrate, 2 is a wiring conductor, 2a is a side surface of the wiring conductor 2, 3 is a core substrate composed of the insulating substrate 1 and the wiring conductor 2, 4 is an insulating layer, 5 is a wiring conductor layer, These mainly constitute the wiring board of the present invention.
[0017]
The insulating substrate 1 constituting the core substrate 3 has a substantially rectangular shape with a thickness of 0.15 to 1.5 mm formed by impregnating an allyl-modified polyphenylene ether resin into a glass cloth in which glass fibers, which are heat-resistant fiber base materials, are woven vertically and horizontally, for example. It is a board | substrate, and has a function which provides intensity | strength to a wiring board while it has a function as a support body of the wiring conductor 2 and the insulating layer 4. FIG. If the thickness of the insulating substrate 1 is less than 0.15 mm, the rigidity of the wiring substrate tends to decrease and warpage tends to occur. If the thickness exceeds 1.5 mm, the wiring substrate becomes unnecessarily thick and the wiring substrate is lightened. Tend to be difficult to do. Therefore, the thickness of the insulating substrate 1 is preferably in the range of 0.15 to 1.5 mm.
[0018]
A wiring conductor 2 made of copper foil is embedded in the surface of the insulating substrate 1 so that the surface thereof is flush with the surface of the insulating substrate 1.
The wiring conductor 2 made of such copper foil has a width of 20 to 200 μm and a thickness of 5 to 50 μm. Each electrode of an electronic component (not shown) such as a semiconductor element mounted together with the wiring conductor layer 5 is externally provided. It functions as a part of a conductive path electrically connected to an electric circuit board (not shown). If the width of the wiring conductor 2 is less than 20 μm, the wiring conductor 2 tends to be easily deformed or disconnected, and if it exceeds 200 μm, a high-density wiring tends not to be formed. Further, when the thickness of the wiring conductor 2 is less than 5 μm, the strength of the wiring conductor 2 tends to be reduced and deformation or disconnection tends to occur, and when it exceeds 50 μm, embedding in the insulating substrate 1 tends to be difficult. . Therefore, the wiring conductor 2 preferably has a width of 20 to 200 μm and a thickness of 5 to 50 μm.
[0019]
Note that the upper and lower wiring conductors 2 may be electrically connected by a through conductor (not shown) formed in the insulating substrate 1. Such a through conductor has a diameter of 30 to 100 μm. For example, a metal powder such as copper or silver / tin alloy and a triazine-based thermosetting material inside a through hole (not shown) provided in the insulating substrate 1. It is formed by embedding a conductor made of resin or the like. When the through conductor is provided, if the diameter is less than 30 μm, formation of the through conductor tends to be difficult, and if it exceeds 100 μm, high-density wiring tends to be unable to be formed. Accordingly, when the through conductor is provided, the diameter is preferably in the range of 30 to 100 μm.
[0020]
In addition, insulating layers 4 containing epoxy resin and wiring conductor layers 5 made of copper plating are alternately stacked on the surface of the core substrate 3 where the wiring conductors 2 are embedded. The insulating layer 4 functions as a support for the wiring conductor layer 5 made of copper plating, has a thickness of 10 to 80 μm, an epoxy resin and an average particle size of 0.01 to 2 μm, and a content of 10 to 50 weight. % Of inorganic insulating filler such as silica, alumina and aluminum nitride.
[0021]
The inorganic insulating filler adjusts the thermal expansion coefficient of the insulating layer 4 to match the thermal expansion coefficient of the wiring conductor layer 5, and forms appropriate irregularities on the surface of the insulating layer 4, so that the wiring conductor layer 5 and the insulating layer 4 Has the function of improving the adhesion. In addition, when the average particle diameter of the inorganic insulating filler is less than 0.01 μm, the inorganic insulating fillers tend to aggregate to form an insulating layer 4 having a uniform thickness, and when the average particle diameter exceeds 2 μm. There is a tendency that the unevenness of the surface of the insulating layer 4 becomes too large and the adhesion between the wiring conductor layer 5 and the insulating layer 4 is lowered. Therefore, the average particle size of the inorganic insulating filler is preferably in the range of 0.01 to 2 μm.
[0022]
Further, if the content of the inorganic insulating filler is less than 10% by weight, the effect of adjusting the thermal expansion coefficient of the insulating layer 4 tends to be small, and if it exceeds 50% by weight, the resin amount of the insulating layer 4 decreases. It tends to be difficult to mold the insulating layer 4. Therefore, the content of the inorganic insulating filler is preferably in the range of 10 to 50% by weight.
[0023]
Further, via holes 6 are formed in the insulating layer 4 by laser processing, and the via holes 6 are filled with a part of the wiring conductor layer 5 made of copper plating so that the insulating layer 4 is sandwiched between the upper and lower sides. The wiring conductor 2, the wiring conductor layer 5, and the wiring conductor layers 5 that are located in the are electrically connected. The wiring conductor layer 5 has a width of 20 to 200 μm, a thickness of 1 to 2 μm, an electroless copper plating layer and a thickness of 10 to 30 μm, and is mounted on a wiring board. It has a function as a conductive path for electrically connecting each electrode of an electronic component such as a semiconductor element to an external electric circuit board.
[0024]
If the width of the wiring conductor layer 5 is less than 20 μm, the wiring conductor layer 5 tends to be deformed or disconnected, and if it exceeds 200 μm, high-density wiring tends not to be formed. Further, when the thickness of the wiring conductor layer 5 is less than 11 μm, the strength of the wiring conductor layer 5 tends to decrease and deformation and disconnection tend to occur. When the thickness exceeds 32 μm, it takes a long time to form the wiring conductor layer 5. There is a tendency to end up. Therefore, the wiring conductor layer 5 preferably has a width of 20 to 200 μm and a thickness of 11 to 32 μm.
[0025]
In the wiring board of the present invention, the side surface 2a of the wiring conductor 2 is roughened, and the insulating layer 4 is formed on the insulating substrate 1 between the side surface 2a of the wiring conductor 2 and the insulating substrate 1. It is embedded through resin, and this is important.
[0026]
According to the wiring board of the present invention, the side surface 2a of the wiring conductor 2 is roughened, and an epoxy resin constituting the insulating layer 4 is interposed between the side surface 2a and the insulating substrate 1 in the insulating substrate 1. Since it is embedded, the epoxy resin interposed between the side surface 2a of the wiring conductor 2 and the insulating substrate 1 serves as an adhesive, and the side surface 2a of the wiring conductor 2 and the epoxy resin are firmly bonded. In addition, a wiring board in which the wiring conductor 2 and the insulating substrate 1 are firmly bonded can be obtained. As a result, after mounting electronic components on the wiring board, a long-term thermal history is repeatedly applied to the wiring board, and thermal stress generated due to a difference in thermal expansion between the insulating board 1 and the wiring conductor 2 is generated between the insulating board 1 and the wiring conductor 2. Even if concentrated on the boundary, no gap is generated between the side surface 2a of the wiring conductor 2 and the insulating substrate 1, and a crack is generated in the insulating layer 4 starting from the gap and the wiring conductor layer 5 is cut. This does not cause a disconnection failure.
[0027]
In addition, according to the wiring board of the present invention, the insulating substrate 1 and the insulating layer 4 are strengthened by the anchor effect of the epoxy resin constituting the insulating layer 4 interposed between the side surface 2 a of the wiring conductor 2 and the insulating substrate 1. As a result, long-term thermal history is repeatedly applied after mounting electronic components on the wiring board, and thermal stress generated by the difference in thermal expansion between the insulating substrate 1 and the insulating layer 4 is concentrated on the boundary between the two. The insulating layer 4 is not peeled off from the insulating substrate 1.
[0028]
When the distance between the side surface 2a of the wiring conductor 2 and the insulating substrate 1 is less than 1 μm, the side surface 2a of the wiring conductor 2 is roughened and the epoxy is interposed between the side surface 2a of the wiring conductor 2 and the insulating substrate 1. It tends to be difficult to fill the resin, and when it exceeds 5 μm, it tends to be difficult to form such a large interval. Therefore, the distance between the side surface 2a of the wiring conductor 2 and the insulating substrate 1 is preferably 1 to 5 μm.
[0029]
Further, when the arithmetic mean roughness Ra of the side surface 2a of the wiring conductor 2 is less than 0.1 μm, the bonding between the side surface 2a of the wiring conductor 2 and the epoxy resin interposed between the insulating substrate 1 is weak. On the other hand, if it exceeds 2 μm, it takes a long time to form such a rough surface, and it tends to be difficult to form. Therefore, the side surface 2a of the wiring conductor 2 preferably has an arithmetic average roughness Ra in the range of 0.1 to 2 μm.
[0030]
The roughening of the side surface 2a of the wiring conductor 2 and the embedding of the wiring conductor 2 in the insulating substrate 1 with an epoxy resin interposed between the side surface 2a of the wiring conductor 2 and the insulating substrate 1 are the methods described below. It is done by.
[0031]
First, by irradiating the surface on which the wiring conductor 2 of the core substrate 3 is embedded with plasma at an output of 0.5 to 3 kw and a gas ratio of oxygen / carbon tetrafluoride = 1/1 for 300 to 500 seconds, The allyl-modified polyphenylene ether resin located on the surface of the insulating substrate 1 and in the vicinity thereof is shrunk to form a gap 7 having a width of 1 to 5 μm between the side surface 2a of the wiring conductor 2 and the insulating substrate 1, and then the gap 7 is immersed in a formic acid / copper ion solution having a temperature of about 25 ° C. for several minutes, so that the side surface 2a of the wiring conductor 2a exposed in the gap 7 has an arithmetic mean roughness of 0.1 to 2 μm. After that, a film made of an epoxy resin and forming an insulating layer 4 is attached to the surface of the core substrate 3 where the wiring conductors 2 are embedded, and thermosetting at 150 to 180 ° C. for several hours. Fill the wiring conductor 2 of the core substrate 3 It carried out by filling the epoxy resin of the insulating layer 4 into the gap 7 while the deposited forming the insulating layer 4 on the surface.
[0032]
Thus, according to the wiring board of the present invention, the side surface 2a of the wiring conductor 2 is roughened and embedded in the insulating substrate 1 with the epoxy resin interposed between the side surface 2a and the insulating substrate 1. Therefore, the epoxy resin interposed between the side surface 2a of the wiring conductor 2 and the insulating substrate 1 serves as an adhesive, and the side surface 2a of the wiring conductor 2 and the epoxy resin are firmly bonded to each other. A wiring substrate firmly bonded to the insulating substrate 1 can be obtained.
[0033]
Note that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention. In this embodiment, the insulating substrate is formed from one layer. Although an example in which the insulating substrate is formed is shown, the insulating substrate is composed of two or more layers, and a plurality of through conductors that electrically connect the wiring conductors and the wiring conductors located above and below may be formed inside. Good.
[0034]
Next, the manufacturing method of the wiring board of this invention is demonstrated in detail based on FIG.
3 (a) to 3 (f) are cross-sectional views of main parts for each step for explaining the method of manufacturing a wiring board according to the present invention, wherein 11 is a transfer sheet base material, and 12 is a transfer sheet. . In FIG. 3, the same members and portions as those in FIGS. 1 and 2 are denoted by the same reference numerals.
[0035]
First, a core formed by embedding a wiring conductor 2 made of copper foil in an insulating substrate 1 impregnated with an allyl-modified polyphenylene ether resin in a heat resistant fiber base so that the surface thereof is flush with the surface of the insulating substrate 1 A substrate 3 is prepared. Such a core substrate 3 is manufactured by the method described below.
[0036]
First, as shown in FIG. 3 (a), a transfer sheet 12 made by adhering a wiring conductor 2 made of a copper foil to a transfer sheet base material 11 made of a heat resistant resin, and uncured heat resistant fibers. A precursor sheet 1a to be an insulating substrate 1 impregnated with an allyl-modified polyphenylene ether resin is prepared.
[0037]
The transfer sheet base 11 is made of a heat-resistant resin such as polyethylene terephthalate (PET) resin or polycarbonate (PC), and a support for forming the wiring conductor 2 by etching the copper foil and the wiring conductor 2 are used. It has a function as a support when transferring.
[0038]
The transfer sheet base material 11 preferably has a thickness of 20 to 50 μm, and if the thickness is less than 20 μm, the rigidity decreases and the wiring conductor 2 tends to be easily deformed when the copper foil is etched. If it exceeds 50 μm, the flexibility tends to decrease and it tends to be difficult to peel off from the insulating substrate 1. Accordingly, the thickness of the transfer sheet substrate 11 is preferably 20 to 50 μm.
[0039]
The thickness of the wiring conductor 2 is preferably 5 to 50 μm, and more preferably 10 to 20 μm. If the thickness of the wiring conductor 2 is less than 5 μm, the strength of the wiring conductor 2 tends to be reduced and deformation or disconnection tends to occur, and if it exceeds 50 μm, embedding in the precursor sheet 1a tends to be difficult. Therefore, the thickness of the wiring conductor 2a is preferably 5 to 50 μm.
[0040]
Such a transfer sheet 12 is formed by peeling a copper foil having a thickness of about 12 μm through an adhesive on one main surface of a transfer sheet substrate 11 made of a heat resistant resin such as polyethylene terephthalate having a thickness of about 25 μm. After bonding, the film-like photosensitive resist is deposited on the copper foil, and the resist is exposed and developed to form an etching mask having a pattern corresponding to the pattern of the wiring conductor 2. It is manufactured by dipping in an iron solution to remove the non-patterned portion of the copper foil by etching, and finally removing the photosensitive resist to form a patterned wiring conductor 2.
[0041]
On the other hand, the precursor sheet 1a which becomes the insulating substrate 1 is made of a heat-resistant fiber such as glass cloth or aramid fiber impregnated with an allyl-modified polyphenylene ether resin and semi-cured, and its surface is embedded with a wiring conductor 2 Has as much plasticity as possible.
[0042]
Next, after laminating the transfer sheet 12 on the surface of the precursor sheet 1a and heat-pressing them, the wiring conductor 2 is thermocompression bonded to the precursor sheet 1a, and then the transfer sheet substrate 11 is transferred from the precursor sheet 1a. After peeling, the wiring conductor 2 is transferred and embedded in the precursor sheet 1a so that the surface thereof is flush with the surface of the precursor sheet 1a.
[0043]
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. In thermocompression bonding, it is better to perform only pressurization prior to heating. If the heating is performed first, the transfer sheet 12 is stretched by the heat, and there is a risk that it is difficult to accurately embed the wiring conductor 2 in a desired position. Accordingly, it is preferable that the thermocompression bonding is performed prior to heating.
[0044]
Furthermore, they were heated and pressurized to thermally cure the allyl-modified polyphenylene ether resin of the precursor sheet 1a, and the wiring conductor 2 was embedded in the insulating substrate 1 so that the surface thereof was flush with the surface of the insulating substrate 1. A core substrate 3 as shown in a sectional view in FIG. In the heat treatment, the precursor sheet 1a is sandwiched from above and below by a releasable sheet made of a fluororesin or the like, and is heat-treated at a pressure of 1 to 5 MPa at a temperature of 150 to 240 ° C. The thermosetting resin is thermally cured.
[0045]
Next, as shown in a cross-sectional view in FIG. 3C, plasma is applied to the core substrate 3 for 300 to 500 seconds under the conditions of an output of 0.5 to 3 kW and a gas ratio of oxygen / carbon tetrafluoride = 1/1. By irradiation, the surface of the insulating substrate 1 where the wiring conductor 2 is embedded and the allyl-modified polyphenylene ether resin located in the vicinity thereof are contracted, and the width between the side surface 2a of the wiring conductor 2 and the insulating substrate 1 is 1 to 5 μm. The gap 7 is formed. In addition, by irradiating the core substrate 3 with plasma, irregularities having an arithmetic average roughness Ra of 0.5 to 3 μm are formed on the surface of the insulating substrate 1. This unevenness can improve the adhesive force between the insulating substrate 1 and the insulating layer 4.
[0046]
Next, as shown in a cross-sectional view in FIG. 3D, the core substrate 3 irradiated with plasma is immersed in a formic acid / copper ion solution at a temperature of about 25 ° C. for several minutes, thereby exposing the wiring exposed in the gap 7. The side surface 2a of the conductor 2a is roughened so as to have irregularities with an arithmetic average roughness of 0.1 to 2 μm.
[0047]
Next, as shown in a cross-sectional view in FIG. 3 (e), a film made of an epoxy resin and serving as an insulating layer 4 is attached to the surface of the core substrate 3 where the wiring conductors 2 are embedded, and several times at 150 to 180 ° C. The insulating layer 4 is deposited on the surface of the core substrate 3 in which the wiring conductor 2 is embedded by time-curing, and the epoxy resin of the insulating layer 4 is filled in the gap 4. The film for the insulating layer 4 is once melted and softened at the time of thermosetting, so that the epoxy resin of the insulating layer 3 is satisfactorily filled in the gap 7 at that time. Then, the wiring conductor 2 embedded in the surface of the insulating substrate 1 and the insulating substrate 1 are firmly bonded by the epoxy resin filled in the gap 7.
[0048]
According to the method for manufacturing a wiring board of the present invention, the surface of the core board 3 in which the wiring conductor 2 is embedded is irradiated with plasma to shrink the allyl-modified polyphenylene ether resin located on the surface and in the vicinity of the wiring conductor 2. The surface 7a is formed between the side surface 2a and the insulating substrate 1, and then the side surface 2a of the wiring conductor 2 exposed in the clearance 7 is roughened, and then the wiring conductor 2 of the core substrate 3 is embedded. The epoxy resin interposed between the side surface 2a of the wiring conductor 2 and the insulating substrate 1 functions as an adhesive because the insulating layer 4 containing the epoxy resin is deposited on the gap 7 and the inside of the gap 7 is filled with the epoxy resin. In addition, since the side surface 2a of the wiring conductor 2 is roughened, the side surface 2a of the wiring conductor 2 and the epoxy resin are firmly bonded, and the wiring substrate 2 and the insulating substrate 1 are firmly bonded. Offer It can be. Further, since the insulating substrate 1 and the insulating layer 4 are firmly bonded by the anchor effect of the epoxy resin interposed between the side surface 2a of the wiring conductor 2 and the insulating substrate 1, the bonding between the insulating substrate 1 and the insulating layer 4 is achieved. Can provide a strong wiring board.
[0049]
The insulating layer 4 has a thickness of 10 to 80 μm, and is composed of an epoxy resin and an inorganic insulating filler such as silica, alumina, and aluminum nitride having an average particle diameter of 0.01 to 2 μm and a content of 10 to 50% by weight. .
[0050]
Next, as shown in a sectional view in FIG. 3F, a wiring conductor layer 5 made of copper plating is deposited on the upper surface of the insulating layer 3. Further, if necessary, the next insulating layer 4 and the wiring conductor layer 5 are laminated thereon to complete the wiring board.
[0051]
In order to deposit the wiring conductor layer 5 made of copper plating on the surface of the insulating layer 4, first, the surface of the insulating layer 4 is roughened by immersing it in a roughening solution such as a permanganate aqueous solution, Immerse in an aqueous solution of palladium catalyst for electroless plating to attach the palladium catalyst to the surface, and further immerse in electroless copper plating solution consisting of copper sulfate, formalin, EDTA sodium salt, stabilizer, etc. for about 30 minutes to make the thickness An electroless copper plating layer of about 1 to 2 μm is deposited. Next, a plating-resistant resin layer is deposited on the surface of the electroless copper plating layer, and a plurality of openings for depositing the electrolytic copper plating layer are formed in the pattern shape of the copper plating wiring conductor layer 5 by exposure and development. Furthermore, several A / dm for electrolytic copper plating solution consisting of sulfuric acid, copper sulfate pentahydrate, chlorine, brightener, etc. ² Then, an electrolytic copper plating layer having a thickness of about 10 to 30 μm is deposited on the inner surface of the opening and the through hole by immersing for several hours while applying the current. Thereafter, the plating-resistant resin layer is peeled off with sodium hydroxide, and the electroless copper plating layer exposed by peeling off the plating-resistant resin layer is etched away with a sulfuric acid-based aqueous solution such as a mixture of sulfuric acid and hydrogen peroxide solution. It is formed by doing.
[0052]
Thus, according to the method for manufacturing a wiring board of the present invention, the epoxy resin interposed between the side surface 2a of the wiring conductor 2 and the insulating substrate 1 functions as an adhesive, and the side surface 2a of the wiring conductor 2 is rough. Therefore, it is possible to provide a wiring board in which the side surface 2a of the wiring conductor 2 and the epoxy resin are firmly bonded, and the wiring conductor 2 and the insulating substrate 1 are firmly bonded. Further, since the insulating substrate 1 and the insulating layer 4 are firmly bonded by the anchor effect of the epoxy resin interposed between the side surface 2a of the wiring conductor 2 and the insulating substrate 1, the bonding between the insulating substrate 1 and the insulating layer 4 is achieved. Can provide a strong wiring board.
[0053]
Note that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention.
[0054]
【The invention's effect】
According to the wiring board of the present invention, the wiring conductor has a roughened side surface and is embedded in the insulating substrate with the epoxy resin interposed between the side surface and the insulating substrate. An epoxy resin interposed between the side surface and the insulating substrate serves as an adhesive, and the side surface of the wiring conductor and the epoxy resin are firmly bonded to each other so that the wiring conductor and the insulating substrate are firmly bonded. Can do. As a result, after mounting electronic components on the wiring board, a long-term thermal history is repeatedly applied to the wiring board, and thermal stress generated by the thermal expansion difference between the insulating board and the wiring conductor is generated at the boundary between the insulating board and the wiring conductor. Even if concentrated, there is no gap between the side surface of the wiring conductor and the insulating substrate, and cracks are generated in the insulating layer starting from the gap, or this crack cuts the wiring conductor layer and causes disconnection failure. It never happens.
[0055]
Further, according to the wiring board of the present invention, the insulating substrate and the insulating layer are firmly bonded by the anchor effect of the epoxy resin interposed between the side surface of the wiring conductor and the insulating substrate, and as a result, the electronic circuit is connected to the wiring substrate. Even if a long-term thermal history is repeatedly applied after mounting a component and the thermal stress generated by the difference in thermal expansion between the insulating substrate and the insulating layer is concentrated at the boundary between them, the insulating layer will be peeled off from the insulating substrate. Nor.
[0056]
According to the method for manufacturing a wiring substrate of the present invention, the surface of the core substrate on which the wiring conductor is embedded is irradiated with plasma to shrink the allyl-modified polyphenylene ether resin located on the surface of the core substrate and in the vicinity thereof. A gap is formed between the side surface of the wiring board and the insulating substrate, and then the side surface of the wiring conductor exposed in the gap is roughened, and then an insulating layer containing epoxy resin is embedded on the surface of the core board where the wiring conductor is embedded. The epoxy resin interposed between the side surface of the wiring conductor and the insulating substrate serves as an adhesive, and the side surface of the wiring conductor and the epoxy resin are strong. A wiring board in which the wiring conductor and the insulating substrate are firmly bonded can be provided. In addition, since the insulating substrate and the insulating layer are firmly bonded by the anchor effect of the epoxy resin interposed between the side surface of the wiring conductor and the insulating substrate, a wiring substrate having a strong bonding between the insulating substrate and the insulating layer is provided. can do.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an example of an embodiment of a wiring board according to the present invention.
FIG. 2 is an enlarged cross-sectional view of a main part of FIG.
FIGS. 3A to 3F are cross-sectional views of main parts for each step for explaining a method of manufacturing a wiring board according to the present invention. FIGS.
[Explanation of symbols]
１ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Insulated substrate
2 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Wiring conductor
2a ・ ・ ・ ・ ・ ・ ・ ・ ・ Side of wiring conductor
3 ... Core substrate
4 ・ ・ ・ ・ ・ Insulation layer
5 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Wiring conductor layer
7: Clearance

Claims (2)

The wiring of the core substrate in which a wiring conductor made of copper foil is embedded in an insulating substrate impregnated with an allyl-modified polyphenylene ether resin in a heat-resistant fiber base so that the surface thereof is flush with the surface of the insulating substrate In the wiring board formed by alternately laminating a plurality of layers of insulating layers containing epoxy resin and wiring conductor layers made of copper plating on the surface where the conductor is embedded, the side surface of the wiring conductor is roughened, and A wiring board, wherein the insulating substrate is embedded with the epoxy resin interposed between the side surface and the insulating substrate. A core substrate is prepared by embedding a wiring conductor made of copper foil in an insulating substrate impregnated with an allyl-modified polyphenylene ether resin in a heat-resistant fiber base so that the surface thereof is flush with the surface of the insulating substrate. A step of irradiating plasma on the surface of the core substrate in which the wiring conductor is embedded to shrink the allyl-modified polyphenylene ether resin located on and near the surface of the core substrate and the side surface of the wiring conductor; A step of forming a gap between the insulating substrate, a step of roughening the side surface of the wiring conductor exposed in the gap, and an insulation containing an epoxy resin on the surface of the core substrate embedded with the wiring conductor And a step of filling the gap with the epoxy resin and a step of depositing a wiring conductor layer made of copper plating on the surface of the insulating layer. Method for manufacturing a wiring substrate characterized by Rukoto.

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