JP3540809B2 - Single-sided circuit board for high density multilayer printed wiring board and high density multilayer printed wiring board - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention High density Manufactured using a single-sided circuit board for a multilayer printed wiring board and the single-sided circuit board High density With regard to multilayer printed wiring boards, especially effective in efficiently manufacturing multilayer printed wiring boards having an interstitial via hole structure with high yield. High density A single-sided circuit board for a multilayer printed wiring board and this single-sided circuit board High density We propose a multilayer printed wiring board.
[0002]
[Prior art]
2. Description of the Related Art A conventional multilayer printed wiring board is formed of a laminate in which a copper-clad laminate and a prepreg are mutually stacked and integrated. This laminate has a surface wiring pattern on its surface and an inner layer wiring pattern between the interlayer insulating layers. These wiring patterns are electrically connected to each other between the inner layer wiring patterns or between the inner layer wiring pattern and the surface wiring pattern through through holes formed in the thickness direction of the laminate.
[0003]
However, in the multilayer printed wiring board having the through-hole structure as described above, it is necessary to secure an area for forming the through-hole, and it is difficult to increase the component mounting density. There is a drawback that it is not possible to sufficiently cope with demands for downsizing, narrow pitch packages, and practical use of MCMs. For this reason, recently, instead of the multilayer printed wiring board having the through-hole structure as described above, a multilayer printed wiring board having an interstitial via hole (IVH) structure which can easily cope with miniaturization and high density of electronic equipment has been developed. Development is underway.
[0004]
The multilayer printed wiring board having the IVH structure is a printed wiring board having a structure in which conductive via holes for connecting conductive layers are provided in each of the interlayer insulating layers forming the laminate. That is, the wiring board is electrically connected between the inner wiring patterns or between the inner wiring pattern and the surface wiring pattern by via holes (buried via holes or blind via holes) which do not penetrate the wiring board. Therefore, the multilayer printed wiring board having the IVH structure does not need to provide a special area for forming a through hole, and can easily realize the miniaturization and high density of the electronic device.
[0005]
Regarding the multilayer printed wiring board having such an IVH structure, for example, on page 57 of the ninth proceedings of the Circuit Packaging Academic Lecture Meeting (March 2, 1995), the development of a multilayer printed wiring board having an all-layer IVH structure was described. Suggestions have been reported. The proposed multilayer printed wiring board has (a) a high-speed fine via hole processing technology using a carbon dioxide laser, (b) adoption of a composite material of aramid nonwoven fabric and epoxy resin as a substrate material, and (c) interlayer connection by filling a conductive paste. Technology, and is manufactured by the following process (see FIG. 1).
[0006]
First, a material in which an aramid nonwoven fabric is impregnated with an epoxy resin is used as a prepreg, and the prepreg is perforated by a carbon dioxide gas laser, and then the hole thus obtained is filled with a conductive paste (FIG. 1). (a)). Next, copper foil is placed on both sides of the prepreg, and heated and pressed by a hot press. As a result, the epoxy resin and the conductive paste of the prepreg are cured, and the copper foils on both sides are electrically connected to each other (see FIG. 1 (b)). Then, a hard double-sided substrate having via holes is obtained by patterning the copper foil by an etching method (see FIG. 1 (c)).
[0007]
The double-sided substrate thus obtained is used as a core layer to form a multilayer. Specifically, on both surfaces of the core layer, a prepreg filled with the above-mentioned conductive paste and a copper foil are sequentially laminated while being aligned, hot-pressed again, and then the uppermost copper foil is etched. To obtain a four-layer substrate (see FIGS. 1 (d) and 1 (e)). In the case of further multi-layering, the above steps are repeated to obtain a six-layer or eight-layer substrate.
[0008]
As described above, the multilayer printed wiring board having the IVH structure according to the conventional technique requires a heating and pressing step by hot pressing and a patterning step of copper foil by etching many times, which makes the manufacturing process complicated. And there is a disadvantage that it takes a long time to manufacture. Moreover, in the multilayer printed wiring board having the IVH structure obtained by such a manufacturing method, it is difficult to correct the patterning defect of the copper foil in the manufacturing process. When the defectiveness occurs, the entire wiring board as a final product becomes defective. In other words, in the above-described conventional manufacturing process, if a defective product is produced even in one of the laminating steps, it must be disposed of another good laminating step, which tends to deteriorate the manufacturing efficiency or the manufacturing yield. There was a fatal drawback.
[0009]
On the other hand, the inventor has previously proposed a single-sided circuit board for a multilayer printed wiring board, which is effectively used for efficiently manufacturing a multilayer printed wiring board having an IVH structure at a high yield, with respect to an insulating hard substrate. A conductor circuit is formed on one side and an adhesive layer is formed on the other side, and the substrate and the adhesive layer are provided with holes penetrating these layers and contacting conductors. A single-sided circuit board for a multilayer printed wiring board characterized by forming via holes filled with a conductive paste is proposed. As a multilayer printed wiring board having an IVH structure, a circuit board electrically connected via an IVH is provided. At least one of them has proposed a multilayer printed wiring board composed of the single-sided circuit board. Then, as a method of manufacturing a multilayer printed wiring board having an IVH structure using the single-sided circuit board,
(A) a step of forming a conductor circuit by etching a metal foil attached to one surface of an insulating hard substrate;
(B). A step of forming an adhesive layer on the surface opposite to the conductor circuit formed on one surface of the substrate,
(C). A step of forming a hole in contact with the conductor through the insulating hard substrate and the adhesive layer, and filling the hole with a conductive paste to produce a single-sided circuit board;
(D). A step of laminating two or more of the single-sided circuit boards or laminating together with another circuit board, and then using the adhesive layer provided on the board to integrate them into a multilayer by one press molding;
A method for manufacturing a multilayer printed wiring board, which is characterized by passing through, is proposed.
[0010]
Since the single-sided circuit board according to this proposal has difficulty in positioning the through hole of the insulating hard substrate and the through hole of the adhesive layer, it is usually bonded to the surface of the insulating hard substrate opposite to the conductor circuit. After the agent layer is formed, the substrate and the adhesive layer are simultaneously drilled to form a hole in contact with a conductor, and the hole is filled with a conductive paste.
[0011]
However, if the single-sided circuit board is desmeared for the purpose of cleaning the conductive circuit surface in contact with the conductive paste filled in the hole, there is a new problem that the uncured adhesive layer is also easily eroded.
[0012]
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and the main purpose of the present invention is to provide an IVH structure without causing a defect due to desmear processing. High density Effectively used to efficiently manufacture multilayer printed wiring boards with high yield High density An object of the present invention is to provide a single-sided circuit board for a multilayer printed wiring board.
Another object of the present invention is to provide an IVH structure constituted by the single-sided circuit board. High density By providing a multilayer printed wiring board, that is, by laminating a smooth single-sided circuit board with little unevenness, an IVH structure having high positional accuracy and good flatness can be obtained. High density It is to provide a multilayer printed wiring board.
[0013]
[Means for Solving the Problems]
As a result of diligent research to achieve the above-described object, the inventor has completed the invention having the following content as a gist configuration. That is,
(1) IVH structure High density As a single-sided circuit board for a multilayer printed wiring board effectively used for efficiently manufacturing a multilayer printed wiring board with a high yield, the present invention A single-sided copper-clad laminate made by attaching copper foil to one surface of an insulating hard substrate made of cured resin A conductor circuit is provided on one surface, and a small-diameter hole penetrating the substrate and in contact with the conductor circuit, and having one end closed is provided on the other surface of the substrate by laser irradiation. The resin residue generated at the bottom of the hole is desmeared, the conductive paste is filled into the hole to form a via hole projecting from the surface of the substrate, and a thermosetting type is formed on the conductive circuit forming surface. Uncured adhesive layer provided Characterized by High density Provided is a single-sided circuit board for a multilayer printed wiring board.
Here, it is desirable that the conductor circuit is formed by etching a copper foil of a single-sided copper-clad laminate in which a copper foil is attached to one surface of an insulating hard substrate.
[0014]
(2) As a multilayer printed wiring board having an IVH structure, the present invention provides a multilayer printed wiring board having a structure in which laminated materials of a circuit board are electrically connected to each other through interstitial via holes, except for a core substrate. At least one of the inner-layer circuit boards is constituted by the single-sided circuit board according to the above (1). High density Provide a multilayer printed wiring board.
[0015]
A method for efficiently manufacturing a multilayer printed wiring board having an IVH structure with a high yield by using the single-sided circuit board according to the above (1) includes:
(A). A single-sided copper-clad laminate made by attaching copper foil to one surface of an insulating hard substrate made of cured resin A step of forming a conductor circuit by etching a copper foil attached to one surface,
(B). The other surface of the insulative hard substrate was in contact with a conductor circuit through the substrate, and one end was closed. Small diameter Hole By laser irradiation Set up and take After removing the resin residue generated at the bottom of the hole by desmearing, Forming a via hole by filling a conductive paste in the hole so as to protrude from the substrate surface,
(C). On the conductive circuit forming surface of the insulating hard substrate Uncured thermosetting type Step of providing a single-sided circuit board by providing an adhesive layer
(D). By laminating one or more of the single-sided circuit boards on the core substrate or with another circuit board, and then using the adhesive layer provided on the single-sided circuit board, the single-sided circuit board can be multi-layered by one press molding. Through the process of integrating High density A method for manufacturing a multilayer printed wiring board is proposed.
Here, it is desirable that the hole reaching the conductor circuit from the other surface of the insulating hard substrate be formed by laser irradiation.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
According to the first embodiment of the present invention, the height of the IVH density Necessary for efficient production of multilayer printed wiring boards with high yield High density An object of the present invention is to provide a single-sided circuit board for a multilayer printed wiring board.
That is, according to the present invention. High density Single-sided circuit boards for multilayer printed wiring boards The one-sided copper-clad laminate obtained by attaching a copper foil to one surface of an insulating hard substrate made of a cured resin A conductor circuit was provided on one surface, and the other surface of the substrate was in contact with the conductor circuit through the substrate and one end was closed. Small diameter Hole By laser irradiation Set up and take The resin residue generated at the bottom of the hole is desmeared, the conductive paste is filled into the hole to form a via hole projecting from the surface of the substrate, and a thermosetting type is formed on the conductive circuit forming surface. Uncured adhesive layer provided Things.
[0017]
Here, in the present invention, the adhesive layer constituting the single-sided circuit board has an IVH structure. High density In producing a multilayer printed wiring board, the single-sided circuit boards are bonded to each other or to another circuit board to be laminated, and play a role of bonding when the layers are multilayered.
[0018]
In the present invention, the conductor circuit constituting the single-sided circuit board has an IVH structure. High density The surface wiring pattern or the inner layer wiring pattern constituting the multilayer printed wiring board. Such a conductor circuit is formed by etching a metal foil attached to one surface of an insulating hard substrate, and is preferably a single-sided copper-clad laminate formed by forming a copper foil on one surface of an insulating hard substrate. Is formed by etching the copper foil.
[0019]
In the present invention, the via hole forming the single-sided circuit board has an IVH structure. High density In producing a multilayer printed wiring board, the circuit plays a role of electrically connecting a conductor circuit of the single-sided circuit board to a conductor circuit on another circuit board to be laminated. That is, a conductive paste filled in a state of protruding from the substrate surface into a hole penetrating the substrate from one surface of the insulative hard substrate and reaching the conductive circuit is provided on another circuit substrate which is adjacently laminated. It adheres to the conductor circuit by thermosetting, and electrically connects the respective conductor circuits.
[0020]
In particular, when the single-sided circuit boards are bonded to each other or to another circuit board to be laminated to form a multilayer, the conductor circuit forming surface of the single-sided circuit board is intended to improve the adhesion strength and connection reliability of each laminated material. The adhesive layer provided on the surface of the insulating hard substrate including the conductive circuit portion is formed of a layer coated with an adhesive, while the conductive paste of the single-sided circuit board is connected to another circuit board to be connected. The hole is desirably filled in such a manner as to protrude from the substrate surface so as to break through the adhesive layer formed on the conductor circuit portion and make surface contact therewith. The height at which the conductive paste protrudes from the substrate surface is desirably 0.5 to 5 μm larger than the thickness of the adhesive layer coated on the conductor circuit portion.
[0021]
When the single-sided circuit board according to the configuration described above is used, the IVH structure High density A multilayer printed wiring board can be efficiently manufactured with a high yield. Hereinafter, a method for manufacturing a multilayer printed wiring board using the single-sided circuit board according to the present invention will be described. That is, each of the following steps,
(A). A single-sided copper-clad laminate made by attaching copper foil to one surface of an insulating hard substrate made of cured resin A step of forming a conductor circuit by etching a copper foil attached to one surface,
(B). The other surface of the insulative hard substrate was in contact with a conductor circuit through the substrate, and one end was closed. Small diameter Hole By laser irradiation Set up and take After removing the resin residue generated at the bottom of the hole by desmearing, Forming a via hole by filling a conductive paste in the hole so as to protrude from the substrate surface,
(C). On the conductive circuit forming surface of the insulating hard substrate Uncured thermosetting type Step of providing a single-sided circuit board by providing an adhesive layer
(D). By laminating one or more of the single-sided circuit boards on the core substrate or with another circuit board, and then using the adhesive layer provided on the single-sided circuit board, the single-sided circuit board can be multi-layered by one press molding. The process of integrating
It is characterized by passing through.
[0022]
According to the present invention High density The method of manufacturing a multilayer printed wiring board can be applied particularly advantageously to the case where desmear treatment is performed after forming holes for via holes. That is, for the insulating hard substrate, an adhesive layer is provided on the surface opposite to the conductive circuit, and a hole is provided through the substrate and the adhesive layer and in contact with the conductive circuit to form a conductive paste. In the configuration according to the previous proposal in which the via hole is formed by filling, if the resist smear is removed to improve the connection reliability of the via hole, the uncured adhesive layer is melted and functions as an adhesive layer. There is a problem that can not be fulfilled. In this regard, according to the above method, the adhesive layer is provided on the same side as the conductor circuit with respect to the substrate, and the via hole is formed before the adhesive layer is formed. This is because a single-sided circuit board having excellent connection reliability can be stably provided. Note that, even in a configuration in which the adhesive layer is provided on the opposite side of the conductor circuit, the via hole can be formed before the adhesive layer is formed. However, it is not an efficient method but disadvantageous in that it is difficult to perforate the adhesive layer in accordance with the via hole.
[0023]
Further, according to the manufacturing method, since the single-sided circuit boards having the conductor circuits on which the predetermined wiring patterns are formed are individually manufactured in advance, in addition to the above-described effects, the presence or absence of defective portions such as the conductor circuits on the single-sided circuit boards is provided. Can be checked before stacking. As a result, in the lamination stage, only a single-sided circuit board having no defective portion is used. Therefore, according to the above-described manufacturing method, the occurrence of defects at the manufacturing stage is reduced, and the IVH structure is reduced. High density A multilayer printed wiring board can be manufactured with a high yield.
[0024]
Further according to the invention High density According to the method of manufacturing a multilayer printed wiring board, it is not necessary to repeat the steps of stacking prepregs and hot pressing, and superimposing one or more single-sided circuit boards on a core board or with other circuit boards, By utilizing the adhesive layer included in the single-sided circuit board, lamination and integration can be performed by a single hot press molding. Further, the multilayer printed wiring board according to the present invention can be manufactured by the same method as a subtractive mass-produced substrate except for a process of forming a via hole. That is, according to the above method, a multilayer printed wiring board having an IVH structure can be efficiently manufactured in a short time without repeating complicated steps.
[0025]
Here, in the above manufacturing method, the reason why the conductive circuit is formed by etching the metal foil is that, according to the etching of the metal foil, an extremely thin conductive circuit pattern is formed with a uniform thickness and a high density. Because it can be.
[0026]
According to the present invention High density In the method for manufacturing a single-sided circuit board for a multilayer printed wiring board, the hole that penetrates the insulative hard board and contacts the conductor circuit is irradiated with a laser beam. It is formed . The reason for this is that it is advantageous to form via holes in a single-sided circuit board with holes having a small diameter as high as possible. Can be easily and densely formed. Further, according to the drilling process using a laser, a hole penetrating the insulating hard substrate and contacting the conductor circuit can be formed without damaging the conductor circuit. As a result, instead of providing a hole that penetrates the prepreg substrate as in the prior art, a hole having one end closed by a conductive circuit is formed. By filling the hole with a conductive paste, a via hole is formed. And the conductor circuit are in surface contact, so that reliable conduction can be obtained.
[0027]
According to the present invention High density In the method for manufacturing a single-sided circuit board for a multilayer printed wiring board, desmear treatment is performed to remove a resin residue remaining on the conductive circuit surface at the bottom of the via hole, for example, a potassium permanganate solution, a mixed solution of chromic acid and sulfuric acid, or the like. This is a process of immersion in According to the present invention, since the desmear treatment is performed before the formation of the adhesive layer, there is no problem caused by the technology of the previous proposal that the uncured adhesive layer is easily melted.
[0028]
In the present invention, a conventionally known core substrate can be used, and its manufacturing method is not particularly limited. In the present invention, it is not necessary to form an adhesive layer on the outermost circuit board.
[0029]
The IVH structure according to the present invention thus manufactured is High density The multilayer printed wiring board is a multilayer printed wiring board having a structure in which laminated materials of a circuit board are electrically connected to each other via an IVH. For high density multilayer printed wiring boards It is characterized by being constituted by a single-sided circuit board.
[0030]
Here, the present invention High density The single-sided circuit board constituting the multilayer printed wiring board is adhered to another circuit board via an adhesive layer. Such other circuit boards include the present invention. For high density multilayer printed wiring boards Either a single-sided circuit board or a conventionally known printed wiring board can be used.
[0031]
The present invention High density Multilayer printed wiring boards are manufactured by various processings commonly performed on printed wiring boards, such as formation of solder resist on the surface, nickel / gold plating or soldering on the surface wiring pattern, drilling, and cavity. Processing, through-hole plating and the like can be performed. Further, the multilayer printed wiring board of the present invention is used for mounting electronic components such as IC packages, bare chips, and chip components.
[0032]
【Example】
FIG. 2 shows an embodiment of the present invention. High density It is a longitudinal section of a multilayer printed wiring board. In this figure, a multilayer printed wiring board 1 has insulating hard substrates 2a and 2b, conductive circuits 3a and 3b formed by etching a metal foil attached to one surface of the substrate, and a conductive circuit forming surface. A single-sided circuit comprising adhesive layers 4a and 4b provided and having via holes 6a and 6b filled with conductive paste 5 in holes that penetrate insulating hard substrates 2a and 2b and contact conductive circuits 3a and 3b. The substrates 7a and 7b are respectively laminated on both sides of the core substrate 8, and the single-sided circuit boards 7c and 7d each having no adhesive layer are respectively laminated on the outermost layers. And the single-sided circuit boards 7a and 7b are bonded to each other by adhesive layers 4a and 4b provided respectively.
[0033]
Here, the conductor circuit 3a of the single-sided circuit board 7a and the conductor circuit 3b of the single-sided circuit board 7b are each formed in a predetermined wiring pattern shape, and an inner layer is formed on the upper surface or the lower surface of the core substrate 8 in the multilayer printed wiring board 1. It is arranged as a wiring pattern. The conductor circuit 3c of the single-sided circuit board 7c and the conductor circuit 3d of the single-sided circuit board 7d are each formed in a predetermined wiring pattern shape, and are arranged as a surface wiring pattern on the upper surface or the lower surface of the multilayer printed wiring board 1. You. Further, the core substrate 8 can be obtained, for example, by forming a through hole in an insulating hard substrate, filling the conductive paste 5, and then forming the conductor circuits 3e on both surfaces. The conductor circuits 3a, 3b, 3c, 3d are formed, for example, by etching the copper foil of a single-sided copper-clad laminate formed by forming a copper foil on one side of an insulating hard substrate 2a, 2b, 2c, 2d. Those formed are preferred.
[0034]
The via holes 6a and 6b are formed to penetrate the insulating hard substrates 2a and 2b in the thickness direction, and the via holes 6c and 6d penetrate the insulating hard substrates 2b and 2d in the thickness direction. The conductive paste 5 is formed Is filled . Of these via holes, 6a is a buried via hole for electrically connecting between conductor circuits 3a and 3e as an inner wiring pattern, and via hole 6b is a conductor between conductor circuits 3b and 3e as an inner wiring pattern. The via hole 6c is a blind via hole to electrically connect between the conductor circuit 3c as the surface wiring pattern and the inner layer wiring pattern 3a, and the via hole 6d is a via hole 6d. Blind via holes that electrically connect between the conductor circuit 3d as the surface wiring pattern and 3b as the inner wiring pattern, all of which constitute interstitial via holes.
[0035]
As the insulating hard substrate 2a, 2b, 2c, 2d, 2e, for example, glass cloth epoxy resin or glass nonwoven epoxy resin, glass cloth bismaleimide triazine resin, aramid nonwoven epoxy resin and the like cured in a plate shape Can be used.
[0036]
The adhesive layers 4a, 4b, and 4e can be made of, for example, an epoxy-based, polyimide-based, bismaleimide triazine-based, acrylate-based, phenol-based resin adhesive, or the like.
[0037]
As the conductive paste, for example, a conductive paste of copper, silver, gold, carbon, or the like can be used.
[0038]
Of the present invention High density The multilayer printed wiring board can mount various electronic components. For example, as shown by a two-dot chain line in FIG. 2, a chip component 9 such as an IC package or a bare chip is mounted on a predetermined portion of the surface wiring pattern 3c. , Can be fixed by the solder 10.
[0039]
Next, according to the embodiment of the present invention shown in FIG. High density A method for manufacturing a multilayer printed wiring board will be described.
(1) First, the single-sided circuit board 7a (17a) of the present invention, which constitutes the multilayer printed wiring board 1 of FIG. 2, is manufactured. This will be specifically described below with reference to FIG.
(A). An insulative hard substrate 12a having a metal foil 13 adhered to one side as shown in FIG. 3 (a) is prepared. It is advantageous to use, for example, a single-sided copper-clad laminate as the insulating hard substrate 12a having the metal foil 13 adhered to one side.
(B). Next, the metal foil 13 is etched and processed into a predetermined pattern shape as shown in FIG. Thus, the conductor circuit 13a is formed. In addition, as an etching method, known general means can be adopted. The conductor circuit 13a is arranged as an inner layer wiring pattern. In order to improve the adhesion between the layers, the surface of the conductor circuit is formed by applying, for example, microetching, rough plating, or double-side roughened copper foil. It is advantageous to roughen the surface using a known means such as.
(C). Next, as shown in FIG. 3 (c), a hole 16 that penetrates the insulating hard substrate 12a in the thickness direction and contacts the conductor is formed, and in order to clean the conductor circuit surface 18 at the bottom of the hole 16, Desmear processing is performed. The hole 16 is preferably formed by irradiating a laser from the side opposite to the conductor forming surface of the insulating hard substrate 12a. As a drilling machine for irradiating this laser, for example, a pulse oscillation type carbon dioxide laser machine can be used. By using such a carbon dioxide laser beam machine, a hole having a small diameter of 60 to 200 μmφ can be formed with high precision. As a result, via holes can be formed with high density, and a small-sized and high-density multilayer printed wiring board can be manufactured. According to such a drilling method of irradiating a laser, a hole can be drilled in a portion of the insulating hard substrate 12a without damaging the conductive circuit 13a. Only the side on which the 13a is not formed is open, and the other end is closed by a conductor circuit. As a result, the via hole and the conductor circuit 13a can be electrically connected reliably. The desmear treatment is performed for the purpose of completely removing the resin residue remaining in the conductor circuit 18 at the bottom of the hole 16 so that the conductor circuit and the conductive paste are electrically connected to each other. It is carried out by immersing in a potassium manganate solution, a mixed solution of chromic acid and sulfuric acid, or the like.
(D). Next, the conductive layer protrudes from the substrate surface as shown in FIG. 3 (d) into the hole 16 so as to break through the adhesive layer formed on the conductor circuit portion of the other substrate and make surface contact therewith. Is filled with the conductive paste 5. As a method for filling the conductive paste 5, for example, a screen printing method using a metal mask can be adopted. At the time of filling, it is advantageous to form a protective mask around the hole 16 in order to form the via hole with high precision. The protective mask can be formed by laminating a film or paper on the insulative hard substrate 12a and making a hole together during the hole making process. In particular, it is advantageous to fill the conductive paste in a state of protruding from the hole 16 in order to realize a via hole having good connectivity with a conductor circuit serving as an inner layer of another circuit board to be superimposed. Further, the filled conductive paste is advantageously precured in order to enhance workability in a later step, and the protective mask is peeled off before lamination.
(E). Next, as shown in FIG. 3 (e), an adhesive layer 14a is formed on the surface of the insulative hard substrate 12a on which the conductor circuit 13a is formed to form a single-sided circuit board 17a. The adhesive layer 14a is pre-cured by applying a predetermined resin adhesive by means of a roll coater, curtain coater, spray coater, screen printing or the like. At this time, the thickness of the adhesive layer is advantageously in the range of 1 to 15 μm on the conductor circuit.
[0040]
(2) In the same process, a conductor circuit 13b and an adhesive layer 14b are formed on one surface of the insulating hard substrate 12b, respectively, and the conductor is formed through the insulating hard substrate. A single-sided circuit board 17b as shown in FIG. 4 in which a contact hole 16 is provided and a via hole filled with the conductive paste 5 is formed.
[0041]
(3) Similarly, a conductor circuit 13c, 13d is formed on one surface of the insulating hard substrate 12c, 12d, and a hole that penetrates the insulating hard substrate and contacts the conductor. The single-sided circuit boards 17c and 17d as shown in FIG. 4 in which the via holes 16 are provided and the conductive paste 5 is filled are formed.
[0042]
(4) Further, a through-hole is formed in the insulating hard substrate 12e by laser processing, drilling, or the like, and after filling the conductive paste 5, a conductor circuit 13e is formed on both surfaces, and an adhesive layer 14e is formed to form a core. The substrate 8 is manufactured.
[0043]
(5) Next, the single-sided circuit boards 17a, 17b, 17c, 17d and the core board 8 are aligned in a predetermined order using guide holes and guide pins provided around the single-sided circuit board and the core board. While overlapping.
[0044]
(6) After each single-sided circuit board is overlaid on the core board in this manner, each single-sided circuit board and the core board are once heated and pressed in a temperature range of 140 ° C to 200 ° C using a hot press. Are integrated into a multilayer by press molding. Note that it is advantageous to use a vacuum hot press as the hot press. In this step, the single-sided circuit boards 17a, 17b, 17c, 17d and the core board 8 superposed via the adhesive layers 14a, 14b, 14e and the core substrate 8 are thermoset with the adhesive layers 14a, 14b, 14e in close contact. Thereby, it is integrated in a multilayer shape. At the same time, the conductive paste 5 is also brought into close contact with the corresponding conductor circuit and thermally cured, thereby forming a via hole, and the multilayer printed wiring board 1 is obtained.
[0045]
[Other embodiments]
(1) In the above embodiment, the four-layer single-sided circuit board was superimposed on the core board. High density Although the multi-layer printed wiring board has been described, the present invention can be similarly applied to the case of three or five or more multi-layers. Alternatively, the single-sided circuit board of the present invention is laminated on a multilayer printed circuit board. High density A multilayer printed wiring board can be manufactured.
(2) Of the present invention High density In the multilayer printed wiring board, the surface wiring pattern may be formed only in a pad shape for mounting chip electronic components.
[0046]
【The invention's effect】
As described above, according to the present invention, High density According to the single-sided circuit board for a multi-layer printed wiring board, it is possible to integrate the multi-layered printed circuit board by a single press molding without causing a problem due to the desmear treatment, and a high-density multi-layered printed wiring board having an IVH structure. Is extremely advantageous in efficiently producing the compound with a high yield.
In addition, the present invention High density Since the multilayer printed wiring board has a structure in which the single-sided circuit boards are joined by an adhesive layer, the multilayer printed wiring board has a high density multilayer printed wiring board having an IVH structure. It can be easily provided without having to.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing one manufacturing process of a multilayer printed wiring board according to a conventional technique.
FIG. 2 according to the invention High density It is a longitudinal section showing an example of a multilayer printed wiring board.
FIG. 3 according to the invention High density It is a longitudinal cross-sectional view which shows an example of the manufacturing process of the single-sided circuit board for multilayer printed wiring boards.
FIG. 4 High density It is a longitudinal cross-sectional view which shows an example of the assembly process of a single-sided circuit board at the time of manufacturing a multilayer printed wiring board.
[Explanation of symbols]
1 multilayer printed wiring board
2a, 2b, 2c, 2d Insulating hard substrate
3a, 3b, 3c, 3d conductor circuit
4a, 4b, 4c, 4d Adhesive layer
5 conductive paste
6a, 6b, 6d Via hole
7a, 7b, 7c, 7d Single-sided circuit board
8 Chip parts
9 Solder
12a, 12b, 12c, 12d Insulating rigid substrate
13 Metal foil
13a, 13b, 13c, 13d Conductor circuit
14a, 14b, 14c, 14d Adhesive layer
16 holes
17a, 17b, 17c, 17d Single-sided circuit board
18 Conductor circuit surface at bottom of hole
21 Multilayer Printed Wiring Board in Another Embodiment
22 Insulating substrate in another embodiment
23 Conductor circuits in other embodiments
24 Adhesive layer in another embodiment
25 Through-holes in other embodiments
26 Via Holes in Other Embodiments

Claims (3)

A conductor circuit is provided on the one surface of the single-sided copper-clad laminate obtained by attaching a copper foil to one surface of an insulating hard substrate made of a cured resin, and the other surface of the substrate is A small-diameter hole that penetrates the substrate and is in contact with the conductor circuit, and one end of which is closed is provided by laser irradiation, and the resin residue generated at the bottom of the hole is desmeared. Forming a via hole protruding from the surface of the substrate, and providing an uncured adhesive layer of a thermosetting type on the conductive circuit forming surface on one side of the high-density multilayer printed wiring board. Circuit board. The single-sided circuit board for a high-density multilayer printed wiring board according to claim 1, wherein the conductor circuit is formed by etching a copper foil of a single-sided copper-clad laminate. 3. A multilayer printed wiring board having a structure in which laminated materials of a circuit board are electrically connected to each other via interstitial via holes, wherein at least one of the inner layer circuit boards excluding the core board is the above-mentioned one or more. A high-density multilayer printed wiring board, comprising a single-sided circuit board according to claim 1.

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