JP3674662B2 - Wiring board manufacturing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a wiring substrate, and more particularly to a method for manufacturing a wiring substrate having through holes penetrating vertically on an insulating substrate.
[0002]
[Prior art]
As electronic devices are miniaturized and densified, wiring boards used in electronic devices are also required to be miniaturized and densified. Examples of such wiring boards include, for example, epoxy resin and polyimide resin on both upper and lower main surfaces of an insulating substrate made of an electrically insulating material such as glass-epoxy resin in which wiring layers made of a metal material such as copper are formed on both upper and lower main surfaces. A build-up multilayer wiring board having a build-up layer in which a resin insulating layer made of a resin material such as fluororesin and a wiring layer made of a metal material such as copper are alternately stacked is known.
[0003]
In such a build-up multilayer wiring board, a through-hole penetrating up and down an insulating substrate (so-called core substrate) is formed, and a through-hole conductor made of a metal material such as copper is deposited in the through-hole. Has been. The through-hole conductor plays a role of electrically connecting the wiring layers formed on the upper and lower main surfaces of the insulating substrate.
[0004]
In such a through hole, in order to flatten the insulating substrate and obtain a good buildup layer, a through hole filling such as a thermosetting resin such as an epoxy resin is formed. Such a through-hole filler is formed by filling an uncured resin material made of a thermosetting resin such as an epoxy resin after forming the through-hole conductor in a through-hole formed in an insulating substrate. It is formed by heat treatment at a temperature of about 150 ° C. and curing. It is desirable that the through-hole filling has the same plane as the surface of the wiring layer and is flat.
[0005]
[Problems to be solved by the invention]
However, even if such through-hole filling has been subjected to surface treatment such as polishing to make it flush with the wiring layer before curing, the wiring layer is reduced by shrinkage of the volume during curing. It tends to be recessed rather than the surface. As a result, the upper and lower main surfaces of the insulating substrate have large steps between the surface of the through-hole filling and the surface of the wiring layer. When a build-up layer is formed by alternately stacking resin insulation layers and wiring layers on both upper and lower main surfaces of such an insulating substrate, it is difficult to accurately form the wiring layer, resulting in disconnection or short circuit. was there.
[0006]
[Means for Solving the Problems]
As a technique for solving such a problem, the wiring board manufacturing method according to claim 1 of the present invention is formed on at least one plane of the insulating substrate having through holes penetrating the upper and lower main surfaces and the insulating substrate. A wiring layer formed on the inner peripheral surface of the through hole and electrically connected to the wiring layer, and the opening end face is substantially flush with the surface of the wiring layer. A method of manufacturing a wiring board comprising a through hole filling material filled in a through hole, the first filling step of filling the through hole with a first resin material, and the first resin material A first curing step for curing the second resin material, a second filling step for filling the second resin material into the recessed portion produced by the first curing step, and a second curing step for curing the second resin material, Specially including To.
[0007]
According to such a manufacturing method, the resin material (first resin material) filled in the through hole is once cured, and the resin (second resin material) is filled again in the recessed portion generated at that time. In addition, the insulating substrate and the through-hole filling can be easily set on the same plane. In addition, even if the 1st resin material and the 2nd resin material contain a solvent, the thing of a solventless type which does not contain a solvent is good. Regardless of the solvent type or the solventless type, the second resin material filled in the portion where the dent is generated after the first resin material is cured is the same resin material as the first resin material. It may also be a resin material having different properties.
[0008]
In the wiring board manufacturing method according to claim 2 of the present invention, the second resin material has a smaller amount of solvent component than the first resin material.
The shrinkage amount of the resin material at the time of curing is affected by the amount of the solvent component contained in the resin material when a resin material containing a solvent component is used. When the resin material is filled in the recessed portion again, if a resin material with a larger amount of solvent component is used than the resin material initially filled, a similar dent will be generated again in the subsequent curing step. , May not be very effective. In addition, it is conceivable to reduce the shrinkage at the time of curing by using a resin material having a small amount of solvent component in advance, but if the amount of the solvent component is small, there is a disadvantage that the filling property into the through hole is deteriorated. However, according to the present invention, both problems can be solved at once by changing the amount of the solvent component contained in the first and second resin materials.
[0009]
That is, according to such a method of manufacturing a wiring board, the first resin material having a relatively large amount of solvent component and good through-hole filling property is used to fill and cure the through-hole, and then cure the resin. By filling the second resin material having a smaller amount of solvent component and a smaller amount of curing shrinkage than the first resin material into the recessed portion that is sometimes generated, it is difficult for the shrinkage to occur again. Therefore, a through-hole filling having substantially the same surface as that of the wiring layer can be easily formed. Since such a wiring board can form a buildup layer correctly, it does not cause defects such as disconnection.
Further, since the first resin material having a relatively large amount of solvent component is used, the filling property into the through hole is good.
In addition, examples of the amount of the solvent component used here include reaction solvents such as amide solvents and ether solvents typified by N, N-dimethylacetamide, but the present invention is not limited thereto. A known material can be applied and applied without departing from the above.
[0010]
According to a third aspect of the present invention, there is provided a wiring board manufacturing method comprising: a first filling step of filling the through hole with a first resin material so as to protrude from the wiring layer; and the first filling material. A first leveling step of leveling so as to be flush with the surface of the wiring layer after being semi-cured, and a first curing step of curing the first resin material that has undergone the first leveling step; The method of manufacturing a wiring board according to claim 1, wherein:
[0011]
The first resin material can be formed so as to be flush with the wiring layer from the time of application. However, when the uncured resin is cured, the amount of cure shrinkage is large, and the dent caused by the cure shrinkage. The part becomes larger. Thereafter, the second resin material to be filled also shrinks at the time of curing and may cause dents again. Therefore, it is preferable that the dent portion is as small as possible. Therefore, the first resin material is formed so as to protrude from the wiring layer and semi-cured. Semi-cured refers to a state where the resin is not completely cured but the curing action has progressed to some extent. A semi-cured state can be achieved by a method in which the heat treatment time is made shorter than the heat treatment time for complete curing. When completely cured, the resin becomes too hard and the leveling process is difficult. Therefore, the leveling process is preferably performed on the first resin material in a semi-cured state. Here, since the curing action of the resin material proceeds to some extent, it is possible to reduce the amount of curing shrinkage in the first curing step after leveling.
[0012]
According to a fourth aspect of the present invention, there is provided a method for manufacturing a wiring board, comprising: a second filling step of filling the through hole with a second resin material so as to protrude from the wiring layer; and the second filling material. Then, after semi-curing, a second leveling step for leveling the surface of the wiring layer to be flush with the surface of the wiring layer and a second curing step for curing the second resin material that has undergone the second leveling step It is a manufacturing method of the wiring board in any one of Claim 1 thru | or 3 characterized by the above-mentioned.
[0013]
Rather than curing the uncured resin formed so as to be flush with the wiring layer, the second resin material can be cured in a semi-cured state so that the amount of curing shrinkage when completely cured is reduced. Further reduction can be achieved. Further, through a surface-conditioning process such as polishing, a through-hole filling having the same plane as the wiring layer and having extremely high flatness can be formed.
[0014]
The method for manufacturing a wiring board according to claim 5 of the present invention includes a plating step of forming a metal layer on an exposed surface of the through-hole filling. It is a manufacturing method of a wiring board. In the wiring board obtained by the method for manufacturing a wiring board according to claims 1 to 3, since the through-hole filling has substantially the same plane as the wiring layer, the upper surface of the through-hole filling and the wiring layer are plated. A flat metal layer can be formed when applied. Further, by forming a metal layer on the through-hole filling, it is possible to form a non-through hole (blind via) also in a region immediately above the through-hole.
[0015]
The method for manufacturing a wiring board according to claim 6 of the present invention is characterized in that the second resin material contains at least one of metal particles and a plating catalyst nucleus. It is a manufacturing method of a wiring board. When the second resin material contains at least one of metal particles such as copper powder and a plating catalyst nucleus such as palladium, the metal layer applied on the through-hole filling and the through-hole filling The adhesion strength can be improved.
[0016]
The first resin material may also contain at least one of metal particles and plating catalyst nuclei in the same or different amount as the second resin material.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in more detail with reference to the drawings. However, the present invention is not limited to these drawings. A typical method for manufacturing a wiring board according to the present invention will be described below.
[0018]
FIG. 1 explains a first embodiment of a method of manufacturing a wiring board according to the present invention. First, a double-sided copper-clad insulating substrate in which a copper foil 2 having a thickness of 12 μm is attached to both upper and lower main surfaces of an insulating substrate 1 made of a glass-epoxy resin composite material (JIS: FR-4) having a thickness of 0.3 mm. 10 is prepared. Next, through holes H are formed in the double-sided copper-clad insulating substrate 10 at a predetermined pitch with a drill (see FIG. 1A).
Thereafter, electroless Cu plating and electrolytic Cu plating (thickness 15 μm) are applied to form a Cu plating layer 2H on the inner peripheral surface of the through hole H (see FIG. 1B).
Further, a dry film (not shown) serving as an etching resist is pasted so as to close the through-hole H, exposed and developed, and the dry film is left so as to slightly cover the edge of the through-hole H. Next, unnecessary copper is removed by etching, and the dry film is peeled off to form the through-hole conductor 3 on the inner peripheral surface of the through-hole H and the wiring layer 4 on the periphery of the through-hole (see FIG. 1C).
[0019]
Next, as shown in FIG. 2A, the through hole H is filled with a resin material 5 (first resin material) such as an epoxy resin. Here, the wiring layer 4 is filled so as to have substantially the same plane.
Thereafter, the resin material 5 is heated and cured at 150 ° C. for 1 hour to form the first resin filled layer 15. By this curing, the resin material 5 contracts to form the recesses 7 (see FIG. 2B).
[0020]
Next, the concave portion 7 is filled with a resin material 8 (second resin material) such as an epoxy resin (see FIG. 2C). The second resin material 8 has less solvent component than the first resin material 5 and is Cu powder. The reason why the Cu powder is contained is to improve the adhesion to the metal layer 12 (see FIG. 6) described later, and it is effective even if a resin material containing metal particles other than Cu powder or a plating catalyst nucleus is used. Is obtained.
[0021]
Thereafter, the second resin material 8 is heated and cured at 150 ° C. for 0.5 hour to form a second resin filled layer. Since the first resin material 5 (first resin filling layer 15) has already been cured, when the second resin material 8 is cured, the first resin material 5 (first resin filling layer 15) is cured. ) Curing shrinkage does not occur. Therefore, only the second resin material in the vicinity of the opening in the through hole H is cured and shrunk, and the amount of curing shrinkage is very small, so even if it shrinks slightly, it is substantially the same as the wiring layer 4. You can maintain a flat surface.
[0022]
In the first embodiment, the first resin material 5 is filled so as to be substantially flush with the wiring layer 4 (see FIG. 2A), but protrudes from the wiring layer 4. It can also be filled as follows. Such a method will be described below as a second embodiment. The same reference numerals are used for the same parts as in the first embodiment.
[0023]
The through hole H of the insulating substrate 1 shown in FIG. 1C is filled with a resin material 5 such as epoxy so as to protrude from the wiring layer 4 (see FIG. 3A). Thereafter, the resin material 5 is semi-cured by heating at 150 ° C. for 0.5 hour (see FIG. 3B). The semi-cured resin material 5 has a recess 7 due to shrinkage. Next, a portion of the semi-cured resin material 5 that is raised from the wiring layer 4 is removed by polishing (see FIG. 3C). In this way, the semi-cured resin material 5 that has been flattened by polishing is cured to form the first resin-filled layer 15 having the recesses 17 (see FIG. 4A).
[0024]
Here, since the resin material 5 is semi-cured, the curing shrinkage has already progressed to some extent, and the shrinkage amount at the time of curing does not become so large. Therefore, the depth (dent amount) of the concave portion 17 formed by curing shrinkage is smaller than that of the first embodiment (see FIG. 2B) in which the uncured resin material 5 is cured at once. . In this case, the degree of semi-curing can be changed by changing the heat treatment time for making the semi-cured state, and the depth (the amount of dents) of the recesses 7 'can be adjusted as appropriate.
[0025]
Next, the concave portion 7 ′ is filled with a resin material 8 (second resin material) such as an epoxy resin as in the first embodiment (see FIG. 4B). The second resin material 8 has a smaller amount of solvent component than the first resin material 5 and contains Cu powder. The reason why the Cu powder is contained is to improve the adhesion to the metal layer 12 described later, and the effect can be obtained even if a resin material containing metal particles other than the Cu powder or a plating catalyst nucleus is used.
[0026]
Thereafter, the second resin material 8 is heat-treated at 120 ° C. for 0.5 hours to be thermally cured, thereby forming the second resin filled layer 18. Since the first resin material 5 has already been cured, the curing shrinkage of the first resin material 5 does not occur when the second resin material 8 is cured. Therefore, since only the second resin material 8 in the recess 17 in the through hole H is cured and shrunk, the amount of cure shrinkage is small, and even if it shrinks slightly, the wiring layer is substantially reduced. 4 can be maintained in the same plane.
[0027]
In the first and second embodiments, an example is shown in which the recesses 7 and 17 are filled with the second resin material 8 substantially flush with the wiring layer 4, but in the following, it protrudes from the wiring layer 4. A method of filling the second resin material as described above will be described as a third embodiment.
First, the second resin material 8 is formed so as to protrude from the wiring layer 4 in the recess 17 formed in the vicinity of the opening of the through hole H shown in FIG. 4A (see FIG. 5A). . Thereafter, the resin material 8 is semi-cured. The semi-cured resin material 8 ′ slightly contracts (see FIG. 5B). Next, a portion raised from the wiring layer 4 in the semi-cured resin material 8 ′ is removed by polishing (see FIG. 5C). The semi-cured resin material 8 ′ thus surface-adjusted by polishing is cured to form the second resin filling layer 18. The semi-cured resin material 8 has already undergone curing shrinkage to some extent, and the amount of shrinkage at the time of curing is almost negligible. Therefore, substantially the same plane as the wiring layer 4 can be maintained even after curing.
[0028]
Furthermore, the metal layer 12 is formed on the resin filling layer 18 shown in FIG. 5C by electroless Cu plating and / or electrolytic Cu plating (see FIG. 6). When the second resin filled layer 18 is formed of a resin material containing at least one of particles and plating catalyst nuclei, the adhesion between the metal layer 12 and the resin filled layer 18 becomes extremely good.
In addition, although the example using the resin material containing the solvent component was shown in the above embodiment, a solvent-free resin material is used for both or one of the first and second resin materials. May be. In any case, since the second resin material is filled and cured again in the concave portion once cured with the first resin material, there is almost no final recess and is the same as the wiring layer (4). A resin filling having a flat surface can be formed.
[0029]
The material of the insulating substrate 1 used in the present invention is not particularly limited, and those having known materials and structures can be used without limitation. For example, paper base material-phenolic resin multilayer substrate, paper base material-epoxy resin multilayer substrate, paper base material-polyester resin multilayer substrate, glass base material-epoxy resin multilayer substrate, paper base material-Teflon resin multilayer substrate, glass base material -Polyimide resin laminated substrate, glass substrate-BT (bismaleimide-triazine) resin resin laminated substrate, synthetic resin substrate such as composite resin substrate, and metal such as aluminum, iron and stainless steel are covered with epoxy resin etc. for insulation treatment Examples thereof include a metal-based insulating substrate or an insulating substrate such as ceramic.
[0030]
When using the laminated body of the some insulated substrate in the manufacturing method of the wiring board of this invention, the formation method of the laminated body is not specifically limited. Usually, a method of laminating an insulating substrate provided with a wiring layer is adopted as necessary, and generally a pin laminating method and a mass laminating method in which a prepreg is laminated between insulating substrates are suitably used. Further, the number of layers of the insulating substrate is determined according to the necessity of the pattern. The wiring layer is formed between both surfaces or one surface of the laminate and the plurality of insulating substrates. On the other hand, the wiring board of this invention has a wiring layer on both surfaces, when there is one insulating board. As the wiring layer, a known pattern such as a normal circuit pattern, a land portion, or a pad portion is formed as necessary. Moreover, the material of the wiring layer to be formed is not particularly limited, and examples thereof include copper and nickel.
[0031]
As a method for forming the through hole, a known method similar to a normal method for manufacturing a wiring board such as drilling, punching, or laser processing is not particularly limited.
As a method for the surface-adjusting step, a method used for normal wiring substrate polishing such as buff polishing, scrub polishing, belt polishing, and slurry polishing is preferably used.
[0032]
Furthermore, the wiring board obtained by the manufacturing method described in the above embodiment may be further formed by forming a build-up layer as an upper layer by a conventionally known method to form a multilayer wiring board.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of a process of forming a through-hole conductor 3 in a method for manufacturing a wiring board according to a first embodiment.
FIG. 2 is an explanatory diagram of a process of forming a through-hole filling in the wiring board manufacturing method according to the first embodiment.
FIG. 3 is an explanatory diagram of a process of forming a through-hole filling in the wiring board manufacturing method according to the second embodiment.
FIG. 4 is an explanatory diagram of a process of forming a through-hole filling in the wiring board manufacturing method according to the second embodiment.
FIG. 5 is an explanatory diagram of a process of forming a through-hole filling in a wiring board manufacturing method according to a third embodiment.
FIG. 6 is a cross-sectional view showing a state in which a metal layer is formed on the through-hole filling.
[Explanation of symbols]
1: Insulating substrate 2: Copper foil 3: Through-hole conductor 4: Wiring layer 5: First resin material 7, 7 ', 17: Recess 8: Second resin material H: Through hole 2H: Cu plating layer 10: Double-sided copper-clad substrate 12: metal layer 15: first resin filling layer 18: second resin filling layer

Claims (6)

An insulating substrate having through holes penetrating both upper and lower main surfaces;
A wiring layer formed on at least one plane of the insulating substrate;
A through hole conductor formed on the inner peripheral surface of the through hole and electrically connected to the wiring layer;
A through hole filling material filled in the through hole so as to be substantially flush with the surface of the wiring layer at the opening end surface;
A method of manufacturing a wiring board comprising:
A first filling step of filling the through hole with a first resin material;
A first curing step for curing the first resin material;
A second filling step of filling the second resin material into the recessed portion generated by the first curing step;
A second curing step for curing the second resin material;
The manufacturing method of the wiring board characterized by including. The method for manufacturing a wiring board according to claim 1, wherein the second resin material has a smaller amount of solvent component than the first resin material. A first filling step of filling the through hole with a first resin material so as to protrude from the wiring layer;
A first leveling step in which the first filling material is semi-cured and then leveled so as to be flush with the surface of the wiring layer;
A first curing step of curing the first resin material that has undergone the first leveling step;
The method for manufacturing a wiring board according to claim 1, wherein: A second filling step of filling the through hole with a second resin material so as to protrude from the wiring layer;
A second leveling step of leveling the second filling material so as to be flush with the surface of the wiring layer after semi-curing the second filling material;
4. The method for manufacturing a wiring board according to claim 1, further comprising a second curing step of curing the second resin material that has undergone the second leveling step. 5. 5. The method of manufacturing a wiring board according to claim 1, further comprising a plating step of forming a metal layer on the exposed surface of the through-hole filling. 6. The method of manufacturing a wiring board according to claim 1, wherein the second resin material contains either metal particles or a plating catalyst nucleus.

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