JP3154350B2 - Printed wiring board and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed wiring board having a multilayer structure having blind via holes and a method of manufacturing the same.

[0002]

2. Description of the Related Art With the recent increase in the wiring density of electronic devices, multilayer printed wiring boards in which a plurality of wiring layers are stacked have been used as printed wiring boards. In such a multilayer printed wiring board, through holes are generally formed to connect upper and lower outer wiring layers.
In recent years, in order to improve the wiring density, blind via holes connecting between the inner wiring layers or between the inner and outer wiring layers have been formed, and their importance has increased.

Conventionally, as a method of manufacturing a multilayer printed wiring board having blind via holes, a plurality of wiring layers are laminated and drilled to form holes for blind via holes and holes for through holes. The inside is plated. For example, as shown in FIG. 5, a double-sided board 3 (FIG. 5A) in which copper foils 2 are formed on both sides of an insulating layer 1 containing glass cloth or the like is used as a core material. An inner layer circuit 2a is formed (FIG. 4B), and a B-stage prepreg (insulating layer 4) is formed on both surfaces thereof.
The copper foil 2 serving as an outer layer is laminated (see FIG. 3C), and then a blind hole Bh for a blind via hole and a through-hole hole Sh for a through-hole are formed by drilling (FIG. d)), a plating layer 5 is simultaneously formed in these holes (FIG. 7E), and an external circuit is formed (FIG. 7F) to obtain a product.

As another method of manufacturing a multilayer printed wiring board having blind via holes, a method of further laminating a laminate having blind via holes and forming through holes is also known. For example, as shown in FIG. 7, double-sided substrates 3X and 3Y (FIG. 7A) in which copper foils 2 are formed on both surfaces of an insulating layer 1 are used as a core material, and blind holes are formed by drilling the core materials. Bh is formed (FIG. 2B), and a plating layer 5a is further formed (FIG. 2C), and an inner layer circuit 2a is formed (FIG. 2D).
Thereafter, they are laminated via a B-stage prepreg (which becomes the insulating layer 4) (FIG. 3E), and the through-holes Sh are formed.
To form a plating layer 5b (FIG. 9 (g)) and form an external circuit (FIG. 9 (h)) to obtain a product.

[0005]

However, as shown in FIG. 5, a method of forming a blind hole and a through hole hole by drilling after laminating a plurality of wiring layers and plating, as shown in FIG. 5, is shown in FIG. In general, the apex angle θ of the drill bit is an angle of 115 to 130 ° and the thickness of the inner layer circuit 2a and the insulating layer 4 is thin, so that the position of the drill bit is controlled in the depth direction of the wiring board. It is difficult.
Therefore, considering the bit shape of the drill, there is a problem that it is difficult to manufacture a wiring board having an insulating layer having a thickness of 0.2 mm or less.

[0006] The use of a flat drill bit can alleviate the difficulty of controlling the position of the cutting edge of the drill, but such a drill cannot be used if the diameter is 0.5 mm or less because it breaks. Only large diameters can be used. Therefore, the diameter of the blind via hole cannot be reduced, and it is not possible to meet the demand for higher density of the wiring board.

On the other hand, as shown in FIG. 7, in a method of further laminating a laminated plate having a blind via hole and forming a through hole, plating of a blind hole Bh and plating of a through hole Sh are separately performed. However, there is a problem that the number of plating steps increases and the manufacturing cost increases. Further, the plating layer 5a and the plating layer 5b overlap with the outermost layer to be etched in forming the outer layer circuit, so that the total plating thickness is increased (usually 80 μm).
m or more), there is a problem that formation of a fine pattern becomes difficult. Further, at the time of laminating the laminate having the blind via hole formed therein (FIG. 7E), the resin 4 of the B-stage prepreg passes through the blind hole Bh as shown in FIG.
There is a problem that B exudes to the outer layer, and the work of removing the exuded resin is required separately.

As a method for manufacturing a printed wiring board, a method of forming a blind via hole by forming a blind hole by chemical or laser processing without using a drill has been studied. However, the insulating layer of a printed wiring board is usually used to increase dimensional stability.
Since it has a composite structure of a glass cloth, a glass filler, a reinforcing material such as aramid fiber, and an imide resin or the like, it is difficult to process with a chemical or laser. On the other hand, if the insulating layer is formed only from the imide resin without using the reinforcing material, the processing becomes relatively easy, but the insulating property and the mechanical strength cannot be improved.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art. In a method of manufacturing a multilayer printed wiring board having blind via holes, the number of plating steps is reduced to improve productivity, and the manufacturing cost is reduced. And to form a highly reliable and fine pattern.

[0010]

As a first finding, the present inventors have found that, when a laminate having a hole for a blind via hole penetrated therethrough is further laminated with a core material, the laminate having the hole penetrated and a core are formed. If the C-stage prepreg is used as the prepreg to be interposed between the material and the C-stage prepreg without using the B-stage prepreg, the resin that seeps out of the holes can be greatly reduced. It is necessary to use an adhesive to make it equal to or more than the case of using the B-stage prepreg. In addition, heat resistance, pressure resistance, If a permanent mask layer with excellent chemical properties is provided and laminated with the core material, the layer of adhesive or resin that has slightly exuded the thickness of the permanent mask layer at the time of lamination will become a pool of resin. Since the function, exuding resin has been found that it is possible to prevent the overflow to the outer layer. Also,
After laminating the laminate and the core material through the holes for the blind via holes in this way, penetrate the holes for the through holes, and then plating, the plating and the through holes for the blind via holes Plating can be performed in the same process, so the plating process can be reduced.In addition, since the entire surface of the blind via hole is covered with a plating layer, the blind via hole is less affected by external air such as humidity. It has been found that delamination during soldering can be eliminated.

Further, the present inventors have made a second finding that
When laminating a laminated plate with holes for blind via holes to be further laminated with a core material, as a prepreg interposed between the laminated plate and the core material with the holes penetrated, an insulating material without using a B-stage prepreg In particular, it has been found in the first finding that the use of a rigid insulating material provides the same effect as the use of the C-stage prepreg.

Further, the inventor of the present invention has, as a third finding,
When laminating a laminated plate with holes for blind via holes to be further laminated with a core material, a B-stage prepreg with a small resin flow is used as a prepreg to be interposed between the laminated plate and the core material with the holes penetrated. For example, it has also been found that the same effect as the use of the C-stage prepreg in the first finding can be obtained, and that the prepreg can maintain the adhesiveness.

The present invention is based on the findings of the present inventors as described above. That is, the first invention is obtained by laminating a permanent mask layer on the second wiring layer of a laminate comprising at least a first wiring layer, an insulating layer, and a patterned second wiring layer. holes permanent mask holes layer by Rukoto passed through the blind via hole in the stacked body was
The thickness portion of the blind via hole is made to function as a resin reservoir, and at least one C-stage prepreg is heated and pressed on the permanent mask layer of the laminate via an adhesive to close one end of the blind via hole. Forming a plated layer in a portion including a hole for use to form a blind via hole for conducting between the first wiring layer and the second wiring layer. provide.

Further, the second invention provides at least the first invention
A permanent mask layer is laminated on the second wiring layer of the laminated board including the wiring layer, the insulating layer, and the patterned second wiring layer, and the obtained laminate is passed through a hole for a blind via hole. thickness portion of the permanent mask layer is allowed hole by Rukoto
Function as a resin reservoir , and further heat-press the insulating material on the permanent mask layer of the laminate via an adhesive to close one end of the hole for the blind via hole, and close the hole for the blind via hole. A method for manufacturing a printed wiring board, comprising the step of forming a blind via hole for conducting a first wiring layer and a second wiring layer by forming a plating layer in a portion including the printed wiring board.

Further, a third aspect of the present invention provides at least the first aspect.
A permanent mask layer is laminated on the second wiring layer of the laminated board including the wiring layer, the insulating layer, and the patterned second wiring layer, and the obtained laminate is passed through a hole for a blind via hole. thickness portion of the permanent mask layer is allowed hole by Rukoto
Function as a resin reservoir , and further heat-press-bond a B-stage prepreg with a small resin flow on the permanent mask layer of the laminate to close one end of the blind via hole hole and include the blind via hole hole A method for manufacturing a printed wiring board is provided, which comprises a step of forming a blind via hole for conducting a first wiring layer and a second wiring layer by forming a plating layer in a portion.

The present invention also provides a printed wiring board manufactured by the above method.

Hereinafter, a method for manufacturing a printed wiring board according to the present invention will be described in detail with reference to the drawings. In addition, the same reference numerals indicate the same or equivalent components even in the drawings showing the above-described prior art.

FIG. 1 is an explanatory diagram of an example of a manufacturing process of a printed wiring board according to the first invention. As shown in the drawing, in this manufacturing process, first, one copper foil 2 is placed on a double-sided substrate 3 having copper foils 2 formed on both surfaces of an insulating layer 1 (FIG. 2A). And the other copper foil is a second wiring layer L2, and the second wiring layer L2
To form an inner layer circuit (FIG. 1B).

In this case, the double-sided substrate 3 used is
In general, the insulating layer 1 is made of a glass cloth impregnated with an epoxy resin having a thickness of 50 to 300 μm, and the copper foil 2 serving as the first wiring layer L1 has a thickness of 35 μm or less and copper serving as the second wiring layer L2. It is preferable to use the foil 2 having a thickness of 20 to 70 μm. When the thickness of the insulating layer 2 is less than 50 μm,
If the insulation reliability between the first wiring layer L1 and the second wiring layer L2 is reduced, and if the thickness of the insulating layer 2 exceeds 300 μm, the plating solution will not be applied during the plating of the blind holes to be performed later.
The wiring layer L2 is not sufficiently reached, and it is difficult to form a good blind via hole. Further, if the thickness of the copper foil 2 serving as the first wiring layer L1 is greater than 35 μm, the first wiring layer L1 is used for plating performed later.
When the pattern is formed, the thickness to be etched is 80
Since it is more than μm, it is difficult to form a fine pattern, which is not preferable.

The pattern forming method of the second wiring layer L2 can be performed by a general method. For example, a dry film is laminated on the copper foil 2 as an etching resist, exposed through a photo tool, developed, etched, and etched. ,
A photographic method of sequentially performing dry film peeling to obtain a desired circuit pattern can be used. Further, as a method of forming a pattern of the etching resist, a screen printing method can be used.

After the pattern is formed on the second wiring layer L2 in this manner, the permanent mask layer 6 is formed on the second wiring layer L2.
Are laminated to obtain a laminate 7 (FIG. 3C). Here, the permanent mask layer 6 is excellent in heatability, pressurization, and chemical resistance,
In the manufacturing process of a printed wiring board, it means a layer that does not deform, break or peel unless it is specially processed by a drill or the like. This permanent mask layer 6 preferably has a thickness of 10 μm or more in order to function as a resin pool in the subsequent laminating step.

As a method of forming such a permanent mask layer 6, for example, a method of applying a solder resist by screen printing, a method of bonding a dry film with a laminator, a method of spraying a solder resist ink with a spray, and the like can be used.

Next, a blind hole Bh serving as a blind via hole is made to penetrate the laminated body 7 (FIG. 4D).
The blind hole Bh is usually provided with a drill (drill diameter: 0. 1).
(About 2 to 0.4 mm), but it may be opened by a punch using a mold or by a laser beam.

After forming the blind hole Bh, at least one end of the blind hole Bh is closed by heating and pressing at least a C-stage prepreg on the permanent mask layer 6 with an adhesive through an adhesive. Can be simultaneously laminated. For example, as shown in FIG. 3E, the adhesive 8, the C-stage prepreg 4C, the B-stage prepreg 4B, the third wiring layer L3 and the fourth wiring layer L4 are formed on the permanent mask layer 6 by the insulating layer 1. The laminated plate 9, the B-stage prepreg 4B, the C-stage prepreg 4C, the adhesive 8, and the laminate 10 formed on both sides of the
The laminate 11 is obtained by thermocompression bonding (FIG. 1F). Here, similarly to the laminate 7, the laminate 10 is obtained by forming a permanent mask layer 6 and a blind hole Bh on a substrate having a fifth wiring layer L5 and a sixth wiring layer L6.

In this case, if a B-stage prepreg is used as the prepreg 4C to be laminated on the permanent mask layer 6 with the adhesive 8 interposed therebetween, the prepreg itself melts at the time of heating and pressing to close the holes Bh for the blind via holes. Therefore, it is necessary to use a C-stage prepreg.

The adhesive 8 is used because it is difficult for the C-stage prepreg 4C to adhere to the permanent mask layer 6 simply by heat and pressure. As the adhesive 8, for example, a heat-curable adhesive obtained by adding a curing agent such as an acid anhydride, an amine or an imidazole compound to an epoxy resin, or an ultraviolet-curable adhesive such as an acrylate ester can be preferably used. In addition, as a method of using it, for example, it is preferable to apply it to the C-stage prepreg 4C before heating and pressing, remove the solvent to make it dry or semi-cured, and dry it by touch. In this case, the application amount is 1 to 50 g.
/ M ² is preferred. When it is less than 1 g / m ² ,
Sufficient adhesion between the stage prepreg 4C and the permanent mask layer 6 cannot be obtained. On the other hand, if it exceeds 50 g / m ² , excess adhesive is melted at the time of heating and pressing, so that it overflows from the resin pool of the permanent mask layer 6 and tends to close the blind hole Bh, which is not preferable.

The same material as that used for a conventional printed wiring board can be used as a laminate material such as another wiring layer and a B-stage prepreg that are heated and pressed together with the C-stage prepreg.

Next, a through hole S
h (see (g) in the figure), and a plating layer 5 is simultaneously formed on the portion including the blind hole Bh and the through hole Sh (see (h) in the figure). The formation of the plating layer 5 may be performed by electroless plating or by using both electroless plating and electrolytic plating in a usual manner, so that the plating layer 5 covers the entire surface of the blind hole Bh. preferable. Thereby, the moisture resistance of the blind via hole can be improved.

After the formation of the plating layer 5, an outer layer circuit is further formed (FIG. 1 (i)) to obtain a product.

In manufacturing the printed circuit board as described above, the existing manufacturing equipment for the printed circuit board is sufficient, and no special equipment is required. Also, no special material is required. Therefore, a printed circuit board can be manufactured using equipment and materials with established reliability, and the reliability of the obtained printed circuit board is also high.

FIG. 2 is an explanatory diagram of an example of a manufacturing process of a printed wiring board according to the second invention. Figures (a) to (d)
Is as described in FIGS. 1A to 1D.

In FIG. 2D, after the blind hole Bh is formed, a rigid insulating material is heated and pressed on the permanent mask layer 6 via an adhesive to close one end of the blind hole Bh. Also in this case, other wiring layers of the printed wiring board can be simultaneously laminated, similarly to the manufacturing process of the printed wiring board shown in FIG. For example, as shown in FIG. 1E, an adhesive 8 and a rigid insulating material 4 are provided on a permanent mask layer 6.
D, B-stage prepreg 4B, laminated board 9 having third wiring layer L3 and fourth wiring layer L4 formed on both sides of insulating layer 1,
The B-stage prepreg 4B, the rigid insulating material 4D, the adhesive 8, and the laminated body 10 are sequentially laminated, and then heat-pressed to obtain a laminated body 11 (FIG. 6F). Here, the laminate 10
Similarly to the laminate 7, the permanent mask layer 6 and the blind holes B are provided on the substrate having the fifth wiring layer L5 and the sixth wiring layer L6.
h.

In this case, when a B-stage prepreg is used as a prepreg to be laminated on the permanent mask layer 6 with the adhesive 8 interposed therebetween, the prepreg itself melts at the time of thermocompression bonding to close the holes Bh for blind via holes. Therefore, it is necessary to use a rigid insulating material.

The rigid insulating material used in the second aspect of the present invention has sufficient heat resistance and rigidity to such an extent that it does not deform or melt during heating and compression to close the blind via hole Bh. Use electrical insulation.
For example, epoxy resin, melamine resin, phenol resin,
A sheet of a thermosetting resin such as a polyimide resin or a urea resin, or a sheet of a thermoplastic resin having a melting point of 170 ° C. or more such as polyether, ether ketone, polyether sulfone, and poiphenylenetel can be preferably used.

As a rigid insulating material, it is more preferable to use a patterned single-sided copper-clad laminate as shown in FIG. That is, the seventh insulation material 4D
It is more preferable to form the wiring layer L7 or the eighth wiring layer L8. This makes it easier to match the coefficient of thermal expansion with other laminated boards, increases the dimensional stability of the completed printed wiring board, and makes it less likely to warp. Further, the total thickness of the printed wiring board itself can be reduced. For example, a six-layer plate can be manufactured without using the core material 9. As such a single-sided copper-clad laminate, those conventionally used can be used, and the insulating material thereof is, for example, a rigid material such as an epoxy resin impregnated glass cloth, a polyimide impregnated cloth, a bismaleimide triazine impregnated glass cloth, or the like. A plate or, preferably, a flexible plate such as polyimide can be used.

The adhesive 8 is used because it is difficult for the rigid insulating material 4D to adhere to the permanent mask layer 6 simply by heat and pressure. The adhesive 8 may be, for example, an acid anhydride or an epoxy resin, as in the printed wiring board shown in FIG.
A heat-curable adhesive to which a curing agent such as an amine or an imidazole compound is added, or an ultraviolet-curable adhesive such as an acrylate ester can be preferably used. In addition, as a method of use, for example, the rigid insulating material 4D
It is preferable that the solvent is removed and the solvent is removed to obtain a dry or semi-cured state, and then dried by touch. in this case,
The coating amount is preferably from 1 to 50 g / m ² . If it is less than 1 g / m ² , the rigid insulating material 4D and the permanent mask layer 6
And sufficient adhesion cannot be obtained. On the other hand, 50 g / m
^If it exceeds ² , the excess adhesive melts at the time of thermocompression bonding and overflows from the resin pool of the permanent mask layer 6 to form the blind hole Bh.
This is not preferable because it makes it easier to close.

As the other wiring layers to be heated and pressed together with the rigid insulating material C and the laminated material such as the B-stage prepreg, the same materials as those used for the conventional printed wiring board can be used.

The subsequent process, that is, FIG.
(I) is as described in FIGS. 1 (g) to (i).

FIG. 3 is an explanatory view of an example of a manufacturing process of a printed wiring board according to the third invention. Figures (a) to (d)
Is as described in FIGS. 1A to 1D.

In FIG. 3D, after the blind holes Bh are formed, the resin flow on the permanent mask layer 6 is small.
The stage prepreg is heat-pressed and its blind hole B
Although one end of h is closed, other wiring layers of the printed wiring board can be simultaneously laminated in this case as in the manufacturing process of the printed wiring board shown in FIG. 1 or FIG. For example, as shown in FIG.
B-stage prepreg 4Bb with small resin flow, B-stage prepreg 4B, laminated board 9 having third wiring layer L3 and fourth wiring layer L4 formed on both surfaces of insulating layer 1, B-stage prepreg 4B, B with small resin flow The stage prepreg 4Bb and the laminated body 10 are sequentially laminated, and then heat-pressed to obtain a laminated body 11 (FIG. 6F). Here, the laminate 1
0, the fifth wiring layer L5 and the sixth
The permanent mask layer 6 and the blind holes Bh are formed on the substrate having the wiring layer L6.

In this case, as a prepreg to be laminated on the permanent mask layer 6 via the adhesive 8, B
If a normal B-stage prepreg is used instead of the stage prepreg, the prepreg itself melts and closes the blind via hole Bh at the time of heating and pressing. Therefore, it is necessary to use a B-stage prepreg having a small resin flow.

As the B-stage prepreg having a small resin flow used in the third invention, a permanent mask can be adhered with sufficient strength at the time of thermocompression bonding, and the B-stage prepreg can be used as a hole for a blind via hole at the time of thermocompression bonding. A material that flows into Bh and does not block the hole Bh is used. That is, a material having almost no fluidity at the time of pressure bonding and showing adhesiveness as an adhesive is used. The degree of resin flow of such a B-stage prepreg having a small resin flow is as follows.
The value of resin flow according to JIS C 6487 is 0.01
-10%, preferably 0.1-1%. If it is less than 0.01%, the curing of the prepreg proceeds too much, and the adhesion with the permanent mask cannot be performed with the desired strength. On the other hand, if it exceeds 10%, the blind-by-hole hole will be closed even if the heating and pressing conditions are changed, for example, even if the pressure is reduced.

The B-stage prepreg having a small resin flow used in the third invention can be obtained by heating a normal B-stage prepreg (resin flow of about 10 to 60%).

It is to be noted that the same material as that used for the conventional printed wiring board can be used as the other wiring layer or the B-stage prepreg to be heated and pressed together with the B-stage prepreg having a small resin flow. .

The subsequent process, that is, FIG.
(I) is as described in FIGS. 1 (g) to (i).

[0046]

According to the method of manufacturing a printed wiring board of the present invention, when forming a blind via hole connecting the first wiring layer and the second wiring layer, the first wiring layer and the second wiring layer are formed.
On the laminated board on which the wiring layers are laminated, a permanent mask layer having excellent heat resistance, pressurization property and chemical resistance is laminated on the second wiring layer in advance, and then the laminate is used for blind via holes. The holes are made to penetrate, and then another wiring layer or the like is laminated by thermocompression bonding.

For this reason, even if the adhesive or the resin exudes from the holes for the blind via holes at the time of thermocompression bonding, the exuded adhesive or the resin accumulates in the thick portion of the permanent mask layer. Or resin can be prevented from covering the first wiring layer exposed in the blind via hole or overflowing to the outer layer.

Further, when another wiring layer or the like is heat-pressed on the permanent mask layer of the laminated body through which the hole for the blind via hole is penetrated, there is an interposition between the permanent mask layer and the other wiring layer or the like. As the prepreg to be used, a C-stage prepreg, a rigid insulating material, or a B-stage prepreg with a small resin flow is used, so that the amount of the resin that seeps out of the blind via hole during the thermocompression bonding can be greatly reduced.

Therefore, in the method of manufacturing a printed circuit board according to the present invention, a laminate having a blind via hole connecting the first wiring layer and the second wiring layer penetrated with another wiring layer and the like are provided. The adhesive and resin that exude from the blind via-holes are small even when heat-pressed, and the adhesive and resin that exudes even though the slightest accumulates in the thickness of the permanent mask layer. The hole for the via hole is not substantially closed. Therefore, the first wiring layer and the second wiring layer are reliably connected by plating in the holes for the blind via holes performed after such heat compression bonding. Also, the resin does not overflow to the outer layer from the blind via hole,
It is not necessary to perform such a resin removing operation prior to the plating step. Furthermore, since the plating layer formed in this manner covers the entire surface of the blind via hole, the blind via hole is less susceptible to external air such as humidity and eliminates delamination during soldering. Becomes possible.

In the method of manufacturing a printed wiring board according to the present invention, a through hole can be formed together with a blind via hole. In this case, another laminated body having the blind via hole penetrated therethrough is formed. After laminating the wiring layers and the like, it is preferable to pass through holes for through holes and then to perform plating. As a result, plating for blind via holes and plating for through holes can be performed in the same step, so that the number of plating steps can be reduced, productivity can be improved, and manufacturing costs can be reduced.
Even when the through holes are formed in this manner, the plating on the outermost wiring layer of the printed circuit board is one layer, and the outermost layer can be formed relatively thin, so that the fine pattern is formed on the outermost layer. It can be formed.

[0051]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on embodiments.

Example 1 A printed wiring board was manufactured according to the manufacturing process shown in FIG. In this case, a TLC-W-551, 0.2 mm thick, copper foil thickness L1 / L2 = 35 μm / 35 μm, manufactured by Toshiba Chemical Co., Ltd., was used as the double-sided substrate as the core material.

An inner layer circuit was patterned by a photographic method as shown in FIG. 4B on a copper foil serving as the second conductive layer L2 of this substrate (FIG. 1B). That is, first, the first conductive layer L
The surfaces of the copper foil serving as the first and second conductive layers L2 are smoothed with sulfuric acid and brushed, and a dry film (Asahi Kasei Kogyo Kogyo Kogyo Kogyo Kogyo Co., Ltd.) Manufactured by Sunfort AQ5044). Next, the film is exposed through a pattern film (manufactured by Oak Co., Ltd., exposing machine HMW-551D), developed with 3% sodium carbonate, etched with a ferric chloride solution, and dried with 3% caustic soda to remove the dry film. A pattern of the second conductive layer L2 was formed. Further, the entire surface of the surface to be the first conductive layer L1 was exposed so that the copper foil remained on the entire surface.

Next, a permanent mask layer 6 was formed as shown in FIG. This permanent mask layer 6 is formed by a thermosetting solder resist ink (manufactured by Taiyo Ink Industries, S-222).
Is applied to the patterned second conductive layer L2 by a screen printing method, and is heated at 160 ° C. and 30 ° C. in a box oven.
This was performed by heating the ink for a minute to cure the ink. In addition,
The printing device for screen printing is LS manufactured by Neurong Industries
-50, the screen plate was Tetron mesh 200, the emulsion thickness was 20 μm, and the thickness of the cured ink thus obtained was 30 μm.

Next, as shown in FIG.
Was opened. This blind hole has a diameter of 0.25 mm in an NC drill machine (H-MARK90J, manufactured by Hitachi Seiko Co., Ltd.).
It was opened with a drill of mm.

Next, a laminate was formed as shown in FIG. In this case, TLP551 ( 0.05 mm in thickness) manufactured by Toshiba Chemical Co., Ltd. is used as the B-stage prepreg 4B, and the same B-stage prepreg (0.1 mm in thickness) is used as the C-stage prepreg 4C at 180 ° C. 30
A cured product of Kg / cm ² for 90 minutes was used. Further, as the adhesive 8 for bonding the C-stage prepreg 4C and the permanent mask layer 6, S-222 manufactured by Taiyo Ink Industry Co., Ltd.
This adhesive was applied to C-stage prepreg 4C at 18 g / m ² and heated at 120 ° C. for 2 minutes to dry the touch. The thickness of the adhesive 8 after touch drying was 15 μm.

The laminated body 9 having the third wiring layer L3 and the fourth wiring layer L4 is composed of the first wiring layer L1 and the second wiring layer L2.
Was formed by using a substrate similar to the double-sided substrate on which was formed, and forming a pattern thereon by a photographic method.

Then, using a laminating press (Vacuum laminating press VH2-1315, manufactured by Kitagawa Seiki), the whole was 1
The laminate was heated and pressed at 80 ° C. and 40 Kg / cm ² for 100 minutes to obtain a laminate 11 (FIG. 6F).

As shown in FIG. 3G, through holes 11 are made to penetrate through the laminated body 11 using an NC drill machine in the same manner as the blind via holes Bh.
The plating was performed as shown in FIG. In this case, first, the entire laminated body was thinly plated by electroless plating, and subsequently, plating having a thickness of 25 μm was formed by electrolytic plating.

Then, a pattern is formed on the first wiring layer L1 and the sixth wiring layer L6 which are the outermost layers, and a pattern as shown in FIG. 4A is obtained as the pattern of the first wiring layer L1. .

Example 2 In the manufacture of the printed wiring board of Example 1, when the permanent mask layer 6 was formed, a thermosetting solder resist ink (manufactured by Taiyo Ink Kogyo, S-222) was used instead of screen printing. , Permanent Dry Film Resist (Hitachi Kasei Kogyo Fotoc SR-2200G-75, Thickness 75
μm) was formed by a photographic method, and a printed wiring board was manufactured in the same manner as in Example 1.

Comparative Example 1 A printed wiring board was manufactured in the same manner as in Example 1 except that the permanent mask layer 6 was not formed.

Comparative Example 2 In the manufacture of the printed wiring board of Example 1, when forming the laminate (FIG. 1E), instead of the C-stage prepreg, a B-stage prepreg (TLP55 manufactured by Toshiba Chemical Corporation) was used.
1. A printed wiring board was manufactured in the same manner as in Example 1 except that the thickness was 0.1 mm.

Example 3 A printed wiring board was manufactured according to the manufacturing process shown in FIG. The specific operation is that instead of the C-stage prepreg used in the process described with reference to FIG.
(Toshiba Chemical Co., TLC-551, 0.1mm thickness,
It was the same as Example 1 except that a copper foil (35 μm thick) was used.

Example 4 In the manufacture of the printed wiring board of Example 3, in forming the permanent mask layer 6, instead of screen-printing a thermosetting solder resist ink (manufactured by Taiyo Ink Kogyo, S-222). , Permanent Dry Film Resist (Hitachi Kasei Kogyo Fotoc SR-2200G-75, Thickness 75
μm) was formed by a photographic method, and a printed wiring board was manufactured in the same manner as in Example 3.

Comparative Example 3 A printed wiring board was manufactured in the same manner as in Example 3 except that the permanent mask layer 6 was not formed.

Example 5 A printed wiring board was manufactured according to the manufacturing process shown in FIG. Specifically, the thickness of the B-stage prepreg 4B used in the process described with reference to FIG. 1E was set to 0.05 mm, and the C-stage prepreg was replaced with a B-stage prepreg 4Bb (0.1 mm) having a small resin flow. Thick, JI
Using a resin flow of 1.5% according to SC 6487),
And it carried out similarly to Example 1 except not using an adhesive agent. In addition, B stage prepreg with small resin flow,
B stage prepreg (TLP55 manufactured by Toshiba Chemical Corporation)
1, thickness 0.1 mm) by heating in a box oven at 150 ° C. for 5 minutes.

Example 6 In the manufacture of the printed wiring board of Example 5, in forming the permanent mask layer 6, instead of screen-printing a thermosetting solder resist ink (manufactured by Taiyo Ink Kogyo, S-222). , Permanent Dry Film Resist (Hitachi Kasei Kogyo Fotoc SR-2200G-75, Thickness 75
μm) was formed by a photographic method, and a printed wiring board was manufactured in the same manner as in Example 5.

Comparative Example 4 A printed wiring board was manufactured in the same manner as in Example 5 except that the permanent mask layer 6 was not formed.

Comparative Example 5 In the manufacture of the printed wiring board of Example 5, when forming the laminate (FIG. 3E), a normal B-stage prepreg (Toshiba Chemical Co., Ltd.) was used instead of the B-stage prepreg with a small resin flow. A printed wiring board was manufactured in the same manner as in Example 3 except that TLP551 (manufactured by TLP551, thickness: 0.1 mm) was used.

Evaluation (Microscopic Observation of Blind Via Hole) Example 1
To 6, and the cross sections of the blind via holes of the printed wiring boards obtained in Comparative Examples 1 to 5 were observed with a microscope. as a result,
In the printed wiring boards of Examples 1 to 6, the plated layer was formed well, but in the printed wiring boards of Comparative Examples 1 to 5, the resin permeated into the holes of the blind via holes, and the first conductive layer L1 The second conductive layer L2 was not connected by the plating layer.

(Conductor Resistance of First Conductive Layer L1 and Second Conductive Layer L2) Further, in Examples 1 to 6, the first conductive layer L1 and the second conductive layer L2 connected by a 90-hole blind via hole were used. When the conductor resistance (conductor resistance between points A and B in FIG. 4A) of the conductive layer L2 was measured, each was 0.6 ohm.

(Thermal Shock Test) A thermal shock test was performed on each of the ten printed wiring boards of Examples 1 to 6 in accordance with JIS C 5012 for 20 cycles, and the first conductive layer L1 and the second conductive The conductor resistance of the layer L2 was measured. As a result, each of the conductor resistances showed a good value of 1 ohm or less.

[0074]

According to the method for manufacturing a printed wiring board of the present invention, the number of plating steps required for manufacturing a multilayer printed wiring board having blind via holes is reduced, thereby improving productivity and reducing manufacturing costs. This makes it possible to form a highly reliable and fine pattern.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a manufacturing process of a multilayer printed wiring board according to a first invention.

FIG. 2 is an explanatory view of a manufacturing process of a multilayer printed wiring board according to a second invention.

FIG. 3 is an explanatory diagram of a manufacturing process of the multilayer printed wiring board according to the third invention.

FIG. 4 is a plan view of a wiring pattern of a first wiring layer and a second wiring layer of the multilayer printed wiring board of the example.

FIG. 5 is an explanatory diagram of a manufacturing process of a multilayer printed wiring board according to a conventional method.

FIG. 6 is an explanatory view of a conventional method of forming a blind hole by drilling a multilayer printed wiring board.

FIG. 7 is an explanatory view of a manufacturing process of a multilayer printed wiring board according to a conventional method.

FIG. 8 is an explanatory diagram of a laminating step of a laminated plate having a blind via hole formed by a conventional method.

[Description of Signs] Bh Blind hole Sh Through hole hole L1 to L8 First wiring layer to Eighth wiring layer 1 Insulating layer 2 Copper foil 2a Inner layer circuit 3 Double-sided board 4 Insulating layer 4B B-stage prepreg 4Bb Resin flow is small B-stage prepreg 4C C-stage prepreg 4D Rigid insulating material 5 Plating layer 6 Permanent mask layer 7 Laminate 8 Adhesive 9 Laminate 10 Laminate 11 Laminate

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-51-2265 (JP, A) JP-A-61-135738 (JP, A) JP-A-2-39486 (JP, A) JP-A-1- 37084 (JP, A) JP-A-2-181997 (JP, A) JP-B-54-35671 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) H05K 3/00-3 / 46

Claims (14)

(57) [Claims] 1. A permanent mask layer is laminated on a second wiring layer of a laminate comprising at least a first wiring layer, an insulating layer and a patterned second wiring layer. to Rukoto is passed through the hole for the blind via holes
The thickness of the permanent mask layer in the hole functions as a resin reservoir
Was further via its adhesive laminate of a permanent mask layer by closing one end of at least C-stage prepreg thermocompression bonding to the hole for the blind via holes, plated portion including the hole for the blind via hole A method for manufacturing a printed wiring board, comprising a step of forming a layer to form a blind via hole for electrically connecting a first wiring layer and a second wiring layer. 2. A laminate including a C-stage prepreg, a B-stage prepreg, and a third wiring layer is sequentially laminated via an adhesive on a permanent mask layer of a laminate having a blind via hole penetrated therethrough. The resulting laminate is passed through a hole for a through hole, and then a plating layer is simultaneously formed on a portion including a hole for a blind via hole and a hole for a through hole to form a first wiring layer and a second wiring layer. 2. The method for manufacturing a printed wiring board according to claim 1, wherein a blind via hole for conducting the second wiring layer and a through hole are formed. 3. The method according to claim 1, wherein the permanent mask layer is a solder resist layer or
The print according to claim 1 or 2, wherein is a dry film.
Manufacturing method of wiring board. 4. A printed wiring board was prepared by the method of any one of claims 1-3. 5. A permanent mask layer is laminated on a second wiring layer of a laminate comprising at least a first wiring layer, an insulating layer and a patterned second wiring layer. to Rukoto is passed through the hole for the blind via holes
The thickness of the permanent mask layer in the hole functions as a resin reservoir
Was further its stack of permanent mask layer through an adhesive thermocompression bonding an insulating material closing the one end of the holes for blind via holes, and plating layer in a portion including a hole for the blind via hole Forming a blind via hole for electrically connecting the first wiring layer and the second wiring layer. 6. The method of claim 5, wherein the printed circuit board insulating material is a copper-clad laminate formed of at least pattern. 7. The method according to claim 5, wherein the insulating material is a flexible copper-clad laminate on which at least a pattern is formed. 8. An insulating material via an adhesive on a permanent mask layer of a laminate having a blind via hole penetrated therethrough,
A laminate including a B-stage prepreg and a third wiring layer are sequentially laminated and heat-pressed, and the obtained laminate is passed through holes for through holes, and then holes for blind via holes and holes for through holes. 6. The method for manufacturing a printed wiring board according to claim 5 , wherein a plating layer is simultaneously formed on a portion including the first wiring layer, a blind via hole for electrically connecting the first wiring layer and the second wiring layer is formed, and a through hole is formed. . 9. The method according to claim 9, wherein the permanent mask layer is a solder resist layer or
Is a dry film.
Manufacturing method of printed wiring board. 10. A printed wiring board manufactured by the method according to claim 5 . 11. A laminate comprising at least a first wiring layer, an insulating layer, and a patterned second wiring layer, a permanent mask layer is laminated on the second wiring layer, and the resultant laminate is obtained. the Rukoto passed through the hole of the blind via hole
The thickness of the perforated permanent mask layer functions as a resin reservoir
Is not further their small B-stage prepreg having a resin flow in the permanent mask layer of the laminate was heated and pressed to close one end of the hole for a blind via hole, the plated layer in the portion including the hole for the blind via hole A method for manufacturing a printed wiring board, comprising the step of forming a blind via hole that forms a conductive layer between a first wiring layer and a second wiring layer. 12. A laminated board including a B-stage prepreg, a B-stage prepreg, and a third wiring layer with a small resin flow are sequentially laminated and heated on a permanent mask layer of a laminated body penetrating a blind via hole. The resulting laminate is passed through a hole for a through hole, and then a plating layer is simultaneously formed on a portion including a hole for a blind via hole and a hole for a through hole to form a first wiring layer and a second wiring layer. 12. The method for manufacturing a printed wiring board according to claim 11, wherein a blind via hole for conducting with the wiring layer is formed and a through hole is formed. 13. The method according to claim 13, wherein the permanent mask layer is a solder resist layer.
Or a dry film.
Manufacturing method of lint wiring board. 14. A printed wiring board manufactured by the method according to claim 11 .