JPH06196856A - Plating method, manufacture of multilayer printed-wiring board using this method and multilayer printed-wiring board - Google Patents

Abstract

PURPOSE:To form a fine anchor structure on the surface of an insulating resin layer and to increase the close contact property between the insulating resin layer and a plated layer (a circuit conductor layer) formed on its surface by jointly using a mechanical roughening treatment by a sandblasting treatment and a chemical etching treatment. CONSTITUTION:A dry sandblasting treatment process in which abrasives 1 are sprayed on the surface of an insulating resin layer 2, after that, a chemical etching treatment process in which the surface of the insulating resin layer 2 is etched chemically and a process in which a conductive layer 4 is plated on the insulating resin layer 2 are executed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer printed wiring board used in electronic equipment and a method for manufacturing the same. In more detail, after alternately laminating the circuit conductor layers and the insulating resin layers on the insulating substrate, the circuit conductor layers are electrically interconnected via the via holes provided in the insulating resin layers. The present invention relates to a plating method to be carried out, a method for manufacturing a multilayer printed wiring board including the plating method, and a multilayer printed wiring board manufactured by using such a method.

[0002]

2. Description of the Related Art A conventional method for manufacturing a multilayer printed circuit board is described in, for example, Japanese Patent Application Laid-Open No. 4-148590. Japanese Unexamined Patent Publication No. 4-148590 discloses a step of forming a first circuit conductor layer by etching a copper foil provided on the upper surface and a lower surface of an insulating substrate, and an insulating resin layer provided with a photo via hole. 1. A step of forming on the circuit conductor layer, a step of chemically roughening the surface of the insulating resin layer after forming a through hole in the insulating substrate, and a step of roughening this insulating resin layer. A second circuit conductor layer is formed on the surface by an electroless copper plating method and an electrolytic copper plating method, and the first and second circuit conductor layers are electrically interconnected through a photo viar and a through hole. And a method of manufacturing a multilayer wiring board including the steps.

In this conventional example, as a pretreatment for the step of forming the electroless copper plating layer on the insulating resin layer, a chemical etching treatment step with potassium permanganate is mainly performed. The purpose of performing this chemical etching process is
The purpose is to improve the adhesion of the electroless plating layer to the insulating resin layer by chemically etching the surface of the insulating resin layer to form fine irregularities on the surface.

[0004]

However, the above-mentioned conventional technique has the following problems. That is, as a pretreatment for forming the electroless copper plating layer,
Even if the surface of the insulating resin layer is chemically etched, there is a problem that sufficient adhesion cannot be obtained between the insulating resin layer and the electroless copper plating.

Further, the reliability of conduction in the blind via holes and the through holes by electroless plating was not sufficient.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a plating method capable of forming a plating layer having excellent adhesion to an insulating resin layer. Especially.

Another object of the present invention is that the circuit conductor layer has excellent adhesion to the underlying insulating resin layer and that the via hole and the through hole (through hole) provided in the insulating resin layer are electrically connected. It is to provide a method for manufacturing a high-density multilayer printed wiring board having excellent reliability in production.

[0008]

A plating method according to the present invention is a method of plating a conductive layer on an insulating resin layer, which comprises a step of forming the insulating resin layer and a surface of the insulating resin layer. A dry sand blasting process of spraying an abrasive to, a chemical etching process of chemically etching the surface of the insulating resin layer that has been subjected to the sand blasting process, and the chemical etching process. And a step of plating the conductive layer on the surface of the insulating resin layer, whereby the above object is achieved.

Preferably, the dry sandblasting step includes a step of spraying an alumina abrasive on the surface of the insulating resin layer by a dry spray method.

Preferably, the dry sandblasting step includes a step of spraying a silicon carbide abrasive on the surface of the insulating resin layer by a dry spray method.

Preferably, a cleaning process for removing the abrasive from the surface of the insulating resin layer is performed between the dry sandblasting process and the chemical etching process.

[0012] Preferably, the cleaning step includes an ultrasonic cleaning step. In one embodiment, after the chemical etching step, a step of adsorbing catalyst particles for the plating step on the surface of the insulating resin layer is performed.

According to the method of manufacturing a multilayer printed wiring board of the present invention, at least one layer is formed on each of the upper and lower surfaces of the substrate.
Forming a multi-layer wiring board by forming a plurality of internal circuit conductor layers, forming an insulative resin layer covering each of the upper surface and the lower surface of the multi-layer wiring board, and determining the insulative resin layer. Forming a via hole at a location, and forming a through hole penetrating the multilayer wiring board at a predetermined location of the multilayer wiring board; and at least for the surface of the insulating resin layer and the inner surface of the through hole. A dry sandblasting step of spraying an abrasive, a chemical etching step of chemically etching the surface of the insulating resin layer, a surface of the insulating resin layer subjected to the chemical etching treatment, and The method includes a step of plating a conductive layer on the inner surface of the through hole, and a step of patterning the conductive layer into a predetermined shape. The above-mentioned object can be achieved.

Preferably, the dry sandblasting step includes a step of spraying an alumina abrasive on the surface of the insulating resin layer by a dry spray method.

Preferably, the dry sandblasting step includes a step of spraying a silicon carbide abrasive on the surface of the insulating resin layer by a dry spray method.

Preferably, a cleaning process for removing the abrasive from the surface of the insulating resin layer is performed between the dry sandblasting process and the chemical etching process.

Preferably, the cleaning step includes an ultrasonic cleaning step. In one embodiment, after the chemical etching step, a step of adsorbing catalyst particles for the plating step on the surface of the insulating resin layer is performed.

The step of forming the multilayer wiring board includes the step of alternately forming the step of forming the internal circuit conductor layer and the step of forming the insulating layer covering the internal circuit conductor layer a plurality of times. Good.

The step of forming the internal circuit conductor layer may include a step of forming a resistance element made of a resistor film so as to be electrically connected to the circuit conductor layer.

Preferably, the sandblasting step is a step of forming irregularities having a surface roughness in the range of 5 to 10 μm on the surface of the resin layer.

In another method for manufacturing a multilayer printed wiring board according to the present invention, a step of forming an internal circuit conductor layer on each of the upper surface and the lower surface of the substrate, and a step of penetrating the internal conductor layer and the substrate. Through the step of forming a hole and the through hole,
A step of electrically connecting the internal circuit conductor layer formed on the upper surface of the substrate and the internal circuit conductor layer formed on the lower surface of the substrate; and a step of filling the inside of the through hole with a resin layer. ,
A step of forming an insulating resin layer covering the internal circuit conductor layer, a step of forming a via hole at a predetermined position of the insulating resin layer, and at least with respect to the surface of the insulating resin layer,
A dry sand blasting process of spraying an abrasive, a chemical etching process of chemically etching the surface of the insulating resin layer, and a chemical etching process on the surface of the insulating resin layer. , The step of plating the conductive layer and the step of patterning the conductive layer into a predetermined shape are included, whereby the above object is achieved.

Preferably, the dry sandblasting step includes a step of spraying an alumina abrasive on the surface of the insulating resin layer by a dry spray method.

Preferably, the dry sandblasting step includes a step of spraying a silicon carbide abrasive on the surface of the insulating resin layer by a dry spray method.

Preferably, a cleaning process for removing the abrasive from the surface of the insulating resin layer is performed between the dry sandblasting process and the chemical etching process.

Preferably, the cleaning step includes an ultrasonic cleaning step. In one embodiment, after the chemical etching step, a step of adsorbing catalyst particles for the plating step on the surface of the insulating resin layer is performed.

An insulating resin layer may be used as the resin layer for filling the through holes.

A conductive resin layer may be used as the resin layer for filling the through holes.

A multilayer printed wiring board according to the present invention includes a substrate having an upper surface and a lower surface, a first circuit conductor layer formed on each of the upper surface and the lower surface of the substrate, and the upper surface and the An insulating resin layer covering each of the lower surface, a via hole provided at a predetermined location of the insulating resin layer, a through hole provided at a predetermined location of the substrate so as to penetrate the substrate, and the insulating property A second layer formed on the resin layer and on the inner wall of the through hole and connected to the first circuit conductor layer via the via hole;
A multilayer printed wiring board including a circuit conductor layer,
The surface of the insulating resin layer has unevenness reflecting the shape of the fine abrasive, the distribution of the unevenness is isotropic along the surface, thereby achieving the above object. It

Preferably, the surface of the insulating resin layer has a surface roughness Rmax in the range of 5 to 10 μm.

Preferably, the insulating resin layer is formed of a material in which fine silica powder is kneaded into the resin layer.

Preferably, the insulating resin layer is formed of a material obtained by kneading silica fine powder with an ultraviolet curable or thermosetting resin layer.

[0032]

According to the present invention, a dry sandblasting step of spraying an abrasive to the surface of the insulating resin layer, and a chemical etching treatment for chemically etching the surface of the insulating resin layer subjected to the sandblasting treatment. The steps are performed before the step of plating the conductive layer. Since mechanical surface roughening by dry sandblasting and chemical etching by an oxidizing agent are used together, a complicated abrasive shape is transferred to the surface of the insulating resin layer, and the surface area thereof is significantly increased. Further, the sandblast treatment improves the shape of the via hole provided on the insulating resin layer, and cleans the exposed surface of the circuit conductor layer and the inner wall surface of the through hole.

[0033]

EXAMPLES The present invention will be described below with reference to examples.

First, a plating method according to an embodiment of the present invention will be described with reference to FIGS. 1 (a) to 1 (d). First, a crushed granular abrasive 1 having a complicated shape as shown in FIG. 1 (a) is prepared. These abrasives 1 are used for sandblasting the insulating resin layer, which will be described in detail below. The abrasive 1 has, for example, a particle size of # 80.
To # 320 (ISO standard) crushed granular alumina or silicon carbide-based inorganic powder.

Next, a step of spraying a large number of abrasives 1 on the surface of the insulating resin layer 2 is carried out by a dry spray method using compressed air. This process is called a dry sandblasting process.

By this sandblasting, a part of the abrasive 1 is embedded in the surface of the insulating resin layer 2 as shown in FIG. 1 (b). Most (not shown) of the abrasive 1 that has not penetrated into the insulating resin layer 2 will remain on the surface of the insulating resin layer 2 after colliding with the surface of the insulating resin layer 2. In a wet spray method in which a liquid substance mixed with the abrasive 1 is sprayed, the liquid 1 covers the surface of the insulating resin layer 2, so that the abrasive 1 is difficult to penetrate into the insulating resin layer 2. . Therefore, in the present invention, it is not preferable to use the wet spray method.

Next, the abrasive 1 embedded in the insulating resin layer 2 and the abrasive 1 remaining on the surface of the insulating resin layer 2
Are removed by a washing step. An air method and / or an ultrasonic cleaning method may be used in the cleaning step. Preferably, this cleaning step removes substantially all of the abrasive 1 from the surface of the insulating resin layer 2. Thus, FIG.
A roughened surface of the insulating resin layer 2 as shown in (c) is obtained. On the surface of the insulating resin layer 2, the abrasive 1
Part of the complicated shape of the resin is transferred, and as a result, the exfoliated resin layer 2
The surface shape of 1 reflects a part of the shape of the abrasive 1.
Here, the insulating resin layer 2 as shown in FIG.
The structure formed on the surface of is referred to as "anchor structure" 3. The surface roughened state of the insulating resin layer 2, that is, the specific state of the anchor structure 3 changes depending on various factors. The factors are, for example, the material, shape, grain size (size) of the abrasive 1, the physical properties of the insulating resin layer 2, the spraying conditions of the abrasive 1, and the like. It is considered that the abrasive 1 which has not penetrated into the surface of the insulating resin layer 2 also contributes to the formation of the anchor structure 3 on the surface by colliding with the insulating resin layer 2.

According to the method of this embodiment, the insulating resin layer 2
The distribution of irregularities (anchor structure 3) formed on the surface of
Isotropic along the surface. If the surface of the insulating resin layer 2 is polished with sand vapor or the like, a surface structure in which a plurality of grooves linearly extends in a certain direction is formed. Here, a structure in which a large number of such linear grooves are formed is not called an "anchor structure". Since the anchor structure 3 obtained in this example is composed of a large number of concave and convex portions, it provides a larger surface area than the structure in which a large number of linear grooves are formed.

In order to make it easier to insert the abrasive 1 into the insulating resin layer 2, the insulating resin layer 2 is preferably made of a flexible and highly elastic material. When more abrasive material 1 is embedded deeper into the insulating resin layer 2, a more complicated anchor shape is formed in the insulating resin layer 2, and as a result, the surface area of the roughened surface is further increased. This improves the adhesion between the plating layer formed in a later step and the insulating resin layer 2. In this embodiment,
As a material for the insulating resin layer 2, a material obtained by kneading a fine powder of silica (about 20% by weight) with an ultraviolet curable epoxy resin is used. This material has a glass transition temperature of 11
It is a relatively flexible and elastic material at 7 ° C. The insulating resin layer 2 made from this material, running sandblasted with abrasive 1 described above at a spray pressure of 3 to 4 Gore / Ke ^2, on the surface of the insulating resin layer 2, roughness Asperities with Rmax of 5 to 12 μm are formed.

Next, the insulating resin layer 2 whose surface has been roughened by sandblasting is dipped in a chromic acid-sulfuric acid based solution or a highly oxidizing solution such as potassium permanganate. In this way, a part of the surface of the insulating resin layer 2 made of the epoxy resin layer is chemically dissolved and removed. By this chemical etching treatment, unevenness having a roughness lower than that of the unevenness formed by the sandblasting treatment is formed. As a result, the surface area is further increased and the adhesion is improved.

FIGS. 2 to 4 are photocopying photographs of the surface of the insulating resin layer 4 after the insulating resin layer 4 has been subjected to the sandblasting treatment and the chemical etching treatment. More specifically, FIG. 2 shows a case where sandblasting is performed using an abrasive having a particle size of # 120, FIG. 3 is a case where sandblasting is performed using an abrasive having a particle size of # 240, and FIG. This corresponds to the case where sandblasting is performed using an abrasive having a particle size of # 320. Further, FIG. 5 corresponds to the case where the sandblast treatment is not performed, and FIG. 6 corresponds to the case where the desmear treatment is performed three times. As can be seen from these figures, the dry sandblasting treatment and the subsequent chemical etching treatment provide a more complicated uneven structure (anchor structure) than the untreated or desmeared insulating resin layer surface.

Next, for example, the activation treatment is carried out by sequentially immersing in a hydrochloric acid acidic solution of tin chloride and palladium chloride. By this activation treatment, the fine particle nuclei (not shown) of metallic palladium, which will serve as the catalyst nuclei for electroless plating, are converted into insulating resin layer 2
Adsorb on the surface of. After that, the insulating resin layer 2 was added to an electroless copper plating solution consisting of an alkaline solution of a copper complex salt and formalin.
Soak. Then, after the metallic copper is grown thin (to a thickness of about 1 μm) by the electroless copper plating, the metallic copper is regrown to a desired thickness by the electrolytic copper plating (thickening). Thus, as shown in FIG. 1 (d),
The conductive metal layer 4 is formed on the insulating resin layer 2.

The following (Table 1) shows the surface roughness of the insulating resin layer 2 and the peeling strength of the conductive metal layer 4 for various particle sizes of the abrasive 1. As shown in (Table 1), according to the plating method of the present embodiment, higher peeling strength can be obtained as compared with the conventional technique.

[0044]

[Table 1]

As described above, the main reason why the adhesion (peeling strength) of the conductive metal layer (plating layer) 4 to the insulating resin layer 2 is improved by the plating method of the present invention is shown in FIG.
As shown in (c) and FIGS. 2 to 4, a complicated anchor structure is formed on the surface of the insulating resin layer 2. As another reason, the chemical etching treatment selectively etches the resin layer component on the inner wall of the recess shown in FIG. 1C, and as a result, silica contained in the insulating resin layer 2 (the above chemical etching treatment is performed). It is thought that fine powder (which is difficult to etch under the conditions) may appear as fine protrusions. By such fine protrusions biting into the surface of the conductive metal layer 4, the adhesiveness is further improved.

Since the surface of the insulating resin layer 2 roughened by the sandblast treatment is in a very activated state, the effect of improving the adsorption of palladium to the insulating resin layer 2 by the activation treatment step is also obtained. is there. As a result, in the electroless copper plating step, metal copper is more uniformly deposited, and the adhesion of the conductive metal layer 4 to the insulating resin layer 2 is improved.

A method of manufacturing a multilayer printed wiring board according to an embodiment of the present invention will be described below with reference to FIGS. 7 (a) to 7 (f). In this example, a manufacturing process of a multilayer printed wiring board having four circuit conductor layers will be described.

First, as shown in FIG. 7 (a), a so-called copper clad in which a metal copper foil 72 having a thickness of 1 ounce or 1/2 ounce is adhered to both upper and lower surfaces of an insulating substrate 71 such as a glass epoxy laminated plate. Prepare a laminated substrate. Then, unnecessary portions of the copper foil 72 are selectively dissolved and removed by a known technique such as a photoetching method. Thus, as shown in FIG. 7B, the first circuit conductor layer 73 having a desired pattern is formed on both upper and lower surfaces of the insulating substrate 71.

Next, the upper and lower surfaces of the insulating substrate 71 are covered with insulating resin layers 74 so as to cover the circuit conductor layer 73, and the circuit conductor layer 73 is insulated. As the insulating resin layer 74, it is necessary to use a resin layer having excellent characteristics such as electric insulation, heat resistance, and chemical resistance. In this embodiment, in order to achieve this object, an ultraviolet-curable epoxy resin is kneaded with an inorganic powder such as alumina or silica to adjust the viscosity.
Stroke, and use the screen printing or marking
The coating method was applied to a film thickness of 80 to 120 μm.

After the insulating resin layer 74 is dried, a mask film is brought into close contact with the insulating resin layer 74, and the insulating resin layer 74 is irradiated with ultraviolet rays through the mask film.
This mask film has a pattern that defines the position and shape of the via hole 75. Next, a portion of the insulating resin layer 74 which has not been irradiated with ultraviolet rays due to masking is dissolved and removed by a developing process. Thus, as shown in FIG. 7C, the via hole 75 is formed at a required position of the insulating resin layer 74. Then, the insulating resin layer 74 is heat-treated at 150 ° C. for 60 minutes to be further hardened.

On the other hand, in addition to the above method, the insulating resin layer 7
4 may be coated with a thermosetting type high heat resistant epoxy resin layer in which an inorganic filler is kneaded, and a via hole 75 may be formed at a required position by a YAG laser or an excimer laser. .

Next, as shown in FIG. 7D, through holes 76 are formed at required positions of the insulating substrate 71 by a drilling method, and then sandblasting and chemical etching with an oxidizing agent are performed. These surface treatments are performed in the same manner as the method described with reference to FIG.
That is, powder having a complicated shape such as alumina or silica is used as a sandblasting abrasive, and this abrasive is sprayed onto the insulating resin layer 74 by a dry spray at a pressure of 3 to 4 go / ke ² . As a result, a rough surface having a complicated shape is formed on the surface of the insulating resin layer 4, and then the epoxy resin layer is etched in a potassium permanganate solution to form a fine rough surface on the insulating resin layer 74. Forming an anchor structure having. By the series of surface treatments, the surface of the insulating resin layer 74, the via hole 75 and the through hole 76 are formed.
The inner wall surface of is roughened.

As a result of evaluating the electrical insulation property and the adhesion of electroless copper plating, it was found that it is preferable to adjust the surface roughness Rmax within the range of 5 to 12 μm by sandblasting. It was found that the conditions are the most suitable for improving the conductor adhesion strength by electroless copper plating without deterioration of electrical insulation characteristics.

Next, the surface-roughened substrate was successively dipped in an activation treatment liquid consisting of stannous chloride and an acidic hydrochloric acid solution of palladium chloride to deposit catalytic nuclei consisting of fine particles of metallic palladium. After that, electroless copper plating is performed to form a conductor metal layer 77 made of metallic copper on the entire surface of the insulating resin layer including the through holes 76, and if necessary, a conductive metal layer combined with electrolytic copper plating is thickened. . Thus, FIG.
The structure shown in (e) is obtained.

Next, the unnecessary portion of the conductive metal layer 77 is selectively dissolved and removed by a known method such as a photoetching method, whereby the second circuit conductor layer 78 required on the surface of the insulating resin layer 74. To form. Thus, FIG.
As shown in (f), the first and second circuit conductor layers 7
A four-layered multilayer printed wiring board in which 3 and 78 are electrically interconnected through the through holes 76 and the via holes 75 is manufactured. Here, the first circuit conductor layer 73 functions as an internal circuit conductor layer, and the second circuit conductor layer 78 functions as an external circuit conductor layer.

In this embodiment, the interlayer insulating resin layer 74 of the multilayer printed wiring board is roughened by a dry sandblasting mechanical method and an oxidizing chemical wet etching method. Thereby, a highly dense and dense uneven surface having a complicated shape can be formed on the insulating resin layer, and a good anchor structure can be formed. Therefore, according to this embodiment, the adhesion of the electroless copper plating can be enhanced. Further, by sandblasting, an appropriate taper can be formed in the through hole 76 and the corner portion of the via hole 75. In addition, the exposed first circuit conductor layer 73
And the inner wall surface of the through hole 76 can be cleaned. For these reasons, the adhesion and throwing power of electroless copper plating are significantly improved, and a multilayer printed wiring board having excellent reliability of electrical connection between circuit conductor layers is provided.

Although the method of manufacturing the multilayer printed wiring board having the four-layer structure has been described in this embodiment, a printed wiring board having a further multilayer structure can be manufactured by repeating the same steps.

In this embodiment, a synthetic resin layer substrate such as a glass epoxy laminated plate is used as the insulating substrate 71.
The insulating substrate material is not limited to the resin layer substrate,
An inner circuit conductor layer 3 formed on the front and back surfaces of a ceramic substrate such as alumina or a metal substrate such as aluminum, copper, iron, or stainless that has been subjected to an insulation treatment.
Is not a method of using a copper foil, but an adhesive is applied to an insulating substrate, and a conductive metal layer is directly formed on the surface by an electroless copper plating method or an electrolytic copper plating method. A circuit conductor layer may be formed.

Next, FIGS. 8A and 8B are diagrams showing a second embodiment of the present invention. In this embodiment, a double-sided through-hole wiring board having through holes filled therein and a core-
The present invention relates to a method for manufacturing a high-density multilayer printed wiring board used as a substrate.

In FIG. 8, after a metal copper foil is formed on both upper and lower surfaces of an insulating substrate 81 such as a glass epoxy laminated plate, the metal copper foil is etched to form an inner circuit conductor layer 83.
To form. After forming the through hole 86 penetrating the circuit conductor layer 83, the inner wall of the through hole 86 is made conductive by the through-hole plating method. After this, the filler 9 is placed inside the through hole 86.
Was filled in to prepare a double-sided wiring board.

As the filling filler 89, an ultraviolet curing type or thermosetting type epoxy resin layer or an acrylic resin layer is used. Further, those obtained by kneading an inorganic insulating powder such as alumina or silica into these resin layers or a paste obtained by kneading a conductive powder such as copper or silver may be used. In that case, both are filled in the through-hole 86 made conductive by a screen printing method or the like. Then, if necessary, a conductor layer for connection is formed on both front and back surface layers of the filling material.

In FIG. 8B, this double-sided wiring board filled with holes is used as a core-substrate, and the first and second embodiments are provided on both front and back surfaces thereof.
An insulating resin layer 84 and a via hole 85 are provided at the required position by the same process as described above, and the surface of the insulating resin layer 84 is roughened by a combination of sandblasting and chemical etching with potassium permanganate. Surfaced,
After that, a conductive metal layer is formed by electroless copper plating and electrolytic copper plating, and finally the required outermost circuit conductor layer 88 is formed by photoetching.

Since this multilayer printed wiring board has a structure in which the through holes are not exposed on the surface, the degree of freedom in the circuit design of the outermost wiring pattern is improved, and as a result, a high density multilayer wiring board can be manufactured. is there.

In this embodiment, the hole-filled double-sided wiring board is used as the core substrate. However, the hole-filled core-substrate is not limited to the double-sided wiring board, and the prepreg insulating sheet is used.
It may be one in which the conductive through holes of a multilayer wiring board in which an inner number of circuit conductor layers made of copper and copper foil are laminated in an arbitrary number are filled.

The third embodiment of the present invention will be described below with reference to FIGS. 9 (a) and 9 (b).

First, the first circuit conductor layer 93 is formed on the upper and lower surfaces of the insulating substrate 91 by the method described above. After that, the resistor film 100 is provided on at least one of the upper surface and the lower surface of the insulating substrate 91 to manufacture a resistance-formed substrate (core substrate) as shown in FIG. 9A. This resistor film 1
00 is formed as follows. That is, a carbon resin type resistor paste is applied by a screen printing method, and then heat curing is performed. After that, the shape of the resistor coating 100 is adjusted by laser trimming, and the resistance value of the resistor coating 100 is adjusted. Instead of this method, an electroless plating method may be used to form the metal-based resistor film.

Next, using the core substrate shown in FIG. 9A, a method similar to the method shown in FIGS. 7A to 7F was performed. More specifically, after the insulating resin layers 94 are applied to both upper and lower surfaces of the core substrate, the via hole 95 is applied to the core substrate.
And a through hole 96 is provided. Then, sandblasting and chemical etching with a potassium permanganate solution are performed to appropriately roughen the insulating resin layer surface 94, the via holes 95, and the inner wall surfaces of the through holes 96. After that, a conductive metal layer is formed on the entire surface of the substrate by electroless copper plating and electrolytic copper plating, and then a required second circuit conductor layer 98 is formed by a known technique such as photoetching.

The multilayer printed wiring board obtained by this method has a structure in which the resistor coating 100 is built in, and therefore has the feature that the density of electronic circuits can be increased.

[0069]

According to the present invention, the surface of the insulating resin layer is subjected to both mechanical surface roughening by sandblasting and chemical etching with an oxidizing agent. As a result, at least the following effects can be obtained.

(1) As a result of the fine anchor structure being formed on the surface of the insulating resin layer, the adhesion between the insulating resin layer and the plating layer (circuit conductor layer) formed on the surface thereof is enhanced.

(2) By sandblasting, the shape of the via hole provided in the insulating resin layer is improved, and the exposed surface of the circuit conductor layer and the inner wall surface of the through hole are cleaned, whereby the circuit is formed. The electrical connection is stabilized by electroless copper plating between the conductor layers, and highly reliable electrical characteristics can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view illustrating a plating method according to an embodiment of the present invention.

FIG. 2 is a photograph showing the particle structure of the surface of the insulating resin layer after sandblasting using an abrasive having a particle size of # 120 and subsequent chemical etching treatment on the insulating resin layer.

FIG. 3 is a photograph showing the particle structure of the surface of the insulating resin layer after sandblasting using an abrasive having a particle size of # 240 and subsequent chemical etching treatment on the insulating resin layer.

FIG. 4 is a photograph showing the particle structure of the surface of the insulating resin layer after sandblasting using an abrasive having a particle size of # 320 and subsequent chemical etching treatment on the insulating resin layer.

FIG. 5 is a photograph showing the particle structure on the surface of the insulating resin layer when the sandblast treatment is not performed.

FIG. 6 is a photograph showing the particle structure on the surface of the insulating resin layer when the desmear treatment is performed three times.

FIG. 7 is a sectional view showing a main manufacturing process of a multilayer printed wiring board according to an embodiment of the present invention.

FIG. 8 is a process sectional view illustrating a method for manufacturing a multilayer printed wiring board having through holes filled with holes according to an embodiment of the present invention.

FIG. 9 is a process cross-sectional view for explaining a method for manufacturing a multilayer printed circuit board having a resistor coating built therein according to an embodiment of the present invention.

[Explanation of symbols]

 1 Grinding Material 2 Insulating Resin Layer 3 Anchor Structure 4 Conductive Metal Layer 71, 81, 91 Insulating Substrate 72 Metal Copper Foil 73, 83, 93 First Circuit Conductor Layer 74, 84, 94 Insulating Resin Layer 75, 85, 95 Bayer hole 76, 96 Through hole 77 Conductive metal layer 78, 88, 98 Second circuit conductor layer 99 Filling filler 100 Resistor film

Claims (27)

[Claims] 1. A method of plating a conductive layer on an insulating resin layer, the method comprising the steps of forming the insulating resin layer and a dry sandblasting step of spraying an abrasive to the surface of the insulating resin layer. A chemical etching step of chemically etching the surface of the insulating resin layer that has been sandblasted, and on the surface of the insulating resin layer that has been chemically etched, And a step of plating the conductive layer. 2. The plating method according to claim 1, wherein the dry sandblasting step includes a step of spraying an alumina abrasive on the surface of the insulating resin layer by a dry spray method. 3. The plating method according to claim 1, wherein the dry sandblasting step includes a step of spraying a silicon carbide abrasive on the surface of the insulating resin layer by a dry spray method. 4. The plating method according to claim 1, wherein a cleaning step for removing the abrasive from the surface of the insulating resin layer is performed between the dry sandblasting step and the chemical etching processing step. 5. The plating method according to claim 4, wherein the cleaning step includes an ultrasonic cleaning step. 6. The plating method according to claim 1, wherein after the chemical etching step, a step of adsorbing catalyst particles for the plating step on the surface of the insulating resin layer is performed. 7. A step of forming a multilayer wiring board by forming at least one internal circuit conductor layer on each of an upper surface and a lower surface of a substrate, and a step of forming each of the upper surface and the lower surface of the multilayer wiring board. A step of forming an insulating resin layer for covering, a step of forming a via hole at a predetermined location of the insulating resin layer, and a step of forming a through hole penetrating the multilayer wiring board at a predetermined location of the multilayer wiring board, A dry sandblasting step of spraying an abrasive to at least the surface of the insulating resin layer and the inner surface of the through hole; and a chemical etching processing step of chemically etching the surface of the insulating resin layer, A step of plating a conductive layer on the surface of the insulating resin layer and the inner surface of the through hole that have been subjected to the chemical etching; A step of patterning into a pattern, and a method for producing a multilayer printed wiring board. 8. The multi-layer printed wiring board according to claim 7, wherein the dry sandblasting step includes a step of spraying an alumina abrasive on the surface of the insulating resin layer and the inner surface of the through hole by a dry spray method. Production method. 9. The multilayer printed wiring board according to claim 7, wherein the dry sandblasting step includes a step of spraying a silicon carbide abrasive to the surface of the insulating resin layer and the inner surface of the through hole by a dry spray method. Manufacturing method. 10. The multilayer printed wiring board according to claim 7, wherein a cleaning step for removing the abrasive from the surface of the insulating resin layer is performed between the dry sandblasting step and the chemical etching step. Production method. 11. The method for manufacturing a multilayer printed wiring board according to claim 10, wherein the cleaning step includes an ultrasonic cleaning step. 12. The method for manufacturing a multilayer printed wiring board according to claim 7, wherein after the chemical etching step, a step of adsorbing catalyst particles for the plating step on the surface of the insulating resin layer is performed. 13. The step of forming a multilayer wiring board includes the step of alternately forming a step of forming an internal circuit conductor layer and a step of forming an insulating layer covering the internal circuit conductor layer a plurality of times. A method for manufacturing a multilayer printed wiring board according to claim 7. 14. The multilayer according to claim 7, wherein the step of forming an internal circuit conductor layer includes the step of forming a resistance element made of a resistor film so as to be electrically connected to the circuit conductor layer. Manufacturing method of printed wiring board. 15. The method for manufacturing a multilayer printed wiring board according to claim 7, wherein the sandblasting step is a step of forming irregularities having a surface roughness in the range of 5 to 10 μm on the surface of the resin layer. 16. A step of forming an internal circuit conductor layer on each of an upper surface and a lower surface of a substrate, a step of forming a through hole penetrating the internal conductor layer and the substrate, and a step of interposing the through hole. And electrically connecting the internal circuit conductor layer formed on the upper surface of the substrate and the internal circuit conductor layer formed on the lower surface of the substrate, and filling the inside of the through hole with a resin layer. A step, a step of forming an insulating resin layer covering the internal circuit conductor layer, a step of forming a via hole at a predetermined location of the insulating resin layer, and grinding at least the surface of the insulating resin layer. A dry sandblasting step of spraying a material, a chemical etching step of chemically etching the surface of the insulating resin layer,
A multilayer printed wiring including a step of plating a conductive layer on the surface of the insulating resin layer subjected to the chemical etching treatment, and a step of patterning the conductive layer into a predetermined shape. Method of manufacturing a plate. 17. A resin layer for filling a through hole,
The method for manufacturing a multilayer printed wiring board according to claim 16, wherein an insulating resin layer is used. 18. A resin layer for filling a through hole,
The method for manufacturing a multilayer printed wiring board according to claim 16, wherein a conductive resin layer is used. 19. The method for manufacturing a multilayer printed wiring board according to claim 16, wherein the dry sandblasting step includes a step of spraying an alumina abrasive on the surface of the insulating resin layer by a dry spray method. 20. The method for manufacturing a multilayer printed wiring board according to claim 16, wherein the dry sandblasting step includes a step of spraying a silicon carbide abrasive on the surface of the insulating resin layer by a dry spray method. 21. A cleaning process for removing the abrasive from the surface of the insulating resin layer is performed between the dry sandblasting process and the chemical etching process.
A method for manufacturing the multilayer printed wiring board according to. 22. The method for manufacturing a multilayer printed wiring board according to claim 21, wherein the cleaning step includes an ultrasonic cleaning step. 23. The method for manufacturing a multilayer printed wiring board according to claim 16, wherein a step of adsorbing catalyst particles for the plating step on the surface of the insulating resin layer is performed after the chemical etching step. 24. A substrate having an upper surface and a lower surface, a first circuit conductor layer formed on each of the upper surface and the lower surface of the substrate, and an insulating property covering each of the upper surface and the lower surface of the substrate. A resin layer, a via hole provided at a predetermined location of the insulating resin layer, a through hole provided at a predetermined location of the substrate so as to penetrate the substrate, and the insulating resin layer and the through hole. A multilayer printed wiring board formed on the inner wall of, and having a second circuit conductor layer connected to the first circuit conductor layer through the via hole, wherein the surface of the insulating resin layer is A multilayer printed wiring board, which has irregularities reflecting the shape of a fine abrasive, and the distribution of the irregularities is isotropic along the surface. 25. The surface of the insulating resin layer has a surface roughness Rma.
The multilayer printed wiring board according to claim 24, wherein x is in the range of 5 to 12 μm. 26. The multilayer printed wiring board according to claim 24, wherein the insulating resin layer is formed of a material in which fine silica powder is kneaded in the resin layer. 27. The multilayer printed wiring board according to claim 24, wherein the insulating resin layer is formed of a material obtained by kneading silica fine powder with an ultraviolet curable or thermosetting resin layer.