JPH07336050A - Manufacture of multilayer printed circuit board - Google Patents

Abstract

PURPOSE:To easily manufacture a thin multilayer printed circuit board in which an interlayer connection is easy and which has excellent wiring density by using adhesive in a B-stage state. CONSTITUTION:A method for manufacturing a multilayer printed circuit board comprises the steps of plating a copper sulfate 2 on the surface of a stainless steel plate 1, then forming a resist pattern 3 on the surface of the sulfate 2, subsequently peeling the resist 3 to form a circuit pattern 4, then black oxidizing the plate 1, adhering an adhesive film 5 on the pattern 4 forming surface, pressurizing it, heating it to a B stage, then peeling the foil formed with the pattern 4 from the plate 1, subsequently opening a hole 6 at a connecting position to meet the pattern 4, then so laminating to integrate that other inner layer plate is brought into contact with the adhesive 5 layer side of the board opened with the hole 6, then opening a hole 9 penetrated through the entire laminated plate, copper-plating the entire surface, and then removing the copper 10 of the surface by etching until the gold-plating is exposed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a multilayer printed wiring board, which allows a fine pattern to be easily obtained.

[0002]

2. Description of the Related Art The width and spacing of printed wiring boards are LSI
With higher integration and higher density of parts mounting, the line width is becoming thinner. However, the conventional method for manufacturing a printed wiring board--for example, in the subtract method of forming a circuit pattern by etching a copper-clad laminate, a dent on the surface copper foil, a disconnection or a short circuit due to a flaw is likely to occur, In addition, since the line width accuracy is reduced due to surface irregularities and waviness, the line width is 100 μm or less. From this, the additive method of plating a required portion to form a circuit or the semi-additive method of plating a required portion of a copper-clad laminate using a copper foil having a thickness of 5 to 9 μm and forming a circuit by quick etching Is suitable for forming a fine pattern. However, in the additive method, due to the roughness of the substrate surface and the copper-free phenomenon of plating, and in the semi-additive method, due to defects and characteristics of the copper-clad laminate itself, 80 μm
It is difficult to form a fine pattern of m or less.

Therefore, as a method of manufacturing a wiring board suitable for forming a fine pattern, a plating resist is formed on a conductive support as disclosed in JP-B-63-37515 and JP-B-1-58878. Then, a metal layer consisting of a metal layer different from the method for removing the holder and another metal layer is formed by plating, and after removing the plating resist, an insulating base material is adhesively laminated on the surface of the metal layer, A method of manufacturing a wiring board in which a conductor circuit is embedded is often used in which the holding body is removed until the metal layer is exposed. According to this manufacturing method, it is possible to stably form a circuit pattern having a line width and a line spacing of about 40 μm with little occurrence of disconnection and short circuit, and to obtain a merit that the substrate surface is smooth without side etching of the circuit pattern. .

On the other hand, as the density of components is increased, the line width,
Not only is the line spacing narrowed, but the number of conductive holes is increasing. The conductive holes used for electrical connection between one wiring layer and another wiring layer are This is done by forming a through hole and plating the inner wall of the hole. However, in this method, since a hole that penetrates the whole is opened, it is necessary to avoid the through hole in the wiring layer that is unrelated to the connection, and this is an obstacle to the degree of freedom in designing and increasing the density of the wiring. There is.

Therefore, instead of using only holes penetrating the entire wiring board, wiring is performed only in adjacent wiring layers.
Methods have been developed for forming so-called via holes. At present, the following two methods are basically known as this method.

The first method is a method of forming adjacent wiring layers first, forming connection holes, and then forming multiple layers.
As an example of this method, a hole is made in a double-sided copper-clad laminate, electroless plating is performed on the inner wall of the hole, or electrolytic plating is performed if necessary to form a connecting conductor, and only unnecessary portions of the copper foil on one side are etched. After removing and leaving the copper foil on the other side, stacking and integrating with other board, make a hole that penetrates the whole and metallize the inner wall of the hole, or wiring layer on the surface of the insulating board Is formed, a layer is formed on the surface of the wiring layer with a photosensitive insulating material, and the surface of this insulating material is roughened by irradiating with light so as to remove only the portion that becomes the conduction hole and developing, There is a method of forming a conductor by electroless plating the circuit conductor on the inner wall of the hole. In all of these techniques, necessary wiring layers are further formed by the same technique to form a multilayer structure.

The second method is a method in which the substrates on which the wiring layers have been previously formed are laminated and then the surface layer and the layer for connecting to the surface layer are connected, and the conductive holes are connected. The feature is that it can be opened only up to the layer. As a specific example of this method, a plurality of wiring layers and insulating layers supporting them are alternately laminated, a copper foil is left on the surface, and a depth reaching a layer to be connected to a circuit on the surface is reached. Well,
How to make a hole with a drill and metallize the inner wall of the hole, or use laser light to make a hole, and place a copper foil on the layer to be connected so that the laser light does not reach the layer that does not require connection. There are ways to leave it.

[0008]

The conventional method for forming these via holes has the following problems. When a double-sided copper-clad laminate is used in the first method, since the circuit is formed on one side, the dimensional change of the substrate is likely to occur, and when laminating and stacking a plurality of substrates, the positional accuracy between the wiring layers is sufficient. Care must be taken and the thickness of the other conductor is increased by the plating performed for connecting the inner wall of the conduction hole, which makes it difficult to reduce the total thickness when the multilayer structure is used. In addition, when a photosensitive material is used as an insulating layer between each wiring layer, there are few materials that can simultaneously satisfy the roughening treatment that enhances the adhesion of plating and the photosensitivity for forming a through hole. Adhesion is not enough.

When a drill is used in the second method, there is variation in the thickness of the substrate, and it is not possible to increase the positional accuracy of stopping the progress of the drill at the connecting point. Moreover, when a laser is used, the device is expensive. In this method, wiring cannot be formed in another layer between the surface layer and the connection layer at the place where a hole is to be formed.

It is an object of the present invention to provide a method for manufacturing a multilayer printed wiring board which facilitates interlayer connection and is excellent in wiring density.

[0011]

The method for manufacturing a multilayer printed wiring board according to the present invention is characterized by including the following steps. That is, (a) a plating resist is formed in a desired shape on the surface of a carrier having conductivity, and a metal layer A different from the condition for removing the carrier and a metal layer B different from the condition for removing the metal layer A are plated. To form a desired circuit pattern and remove the plating resist. (B) A step of providing an adhesive layer on the surface of the holding body on which the circuit pattern is formed, and using this adhesive layer as a B stage. c) A step of making a hole in the substrate. (d) A step of superposing the board having the holes on the adhesive layer side so that another board may come into contact therewith, and heating and pressurizing to integrate the layers. A step of forming a conductor circuit on a necessary portion of the laminated and integrated substrate and removing the holder until the circuit pattern formed by the plating is exposed.

Further, in order to make the circuit pattern formed on the holder finer and realize stable circuit formation, the following steps can be used. (A) In the step of forming a circuit pattern on the surface of the holder, a plating resist is formed in a desired shape on the surface of the holder, and a first metal layer E that can be removed together with the holder is formed by plating. A step of forming a second metal layer composed of a metal layer F different from the removal conditions of the holder and a metal layer G different from the removal conditions of the metal layer F by plating, and removing the plating resist (b) the holder A step of forming an adhesive layer on the surface having a circuit pattern formed on its surface and using this as an adhesive layer B stage (c) a step of making a hole in the substrate (d) an adhesive layer side of the board having the holes A step of stacking so that other boards are in contact with each other, and heating and pressurizing to stack and integrate them. (E) A circuit pattern formed by plating while forming a conductor circuit at a required portion of the board Exposed Until the holder is removed

In order to form a multilayer using such a technique, it is possible to provide the following steps after the above steps. (F) A plating resist is formed in a desired shape on the surface of another holder having conductivity, and a metal layer C different from the removal conditions of the other holder and a metal layer D different from the removal conditions of the metal layer C. To form a desired circuit pattern and remove the plating resist. (G) An adhesive layer is provided on the surface of the other holding body on which the circuit pattern is formed, and the adhesive layer B stage is formed. And (h) a step of making a hole in the other substrate (i) a substrate made in the step (e) is superposed so as to come into contact with the adhesive layer side of the other substrate having the hole formed,
Step of heating and pressurizing to laminate and integrate (j) Steps of repeating the above steps (f) to (i) to form multiple layers, if necessary

Alternatively, (f) in the step of forming a circuit pattern on the surface of the holder, a plating resist is formed in a desired shape on the surface of the holder, and a first metal layer H that can be removed together with the holder is plated. A step of forming a second metal layer, which is formed by the method described above, including a metal layer I different from the removal condition of the holder and a metal layer J different from the removal condition of the metal layer I, and removing the plating resist. g) a step of providing an adhesive layer on the surface of the other holding body on which a circuit pattern is formed and using this adhesive layer as a B stage (h) a step of making a hole in the other substrate (i) the hole On the adhesive layer side of the other substrate where the holes were opened so that the substrate manufactured in the step (e) comes into contact with the adhesive layer side,
Step of heating and pressurizing to laminate and integrate (j) Steps of repeating the above steps (f) to (i) to form multiple layers, if necessary

The holder used in the present invention may be a copper foil which is detachably plated on a stainless steel plate or the like, or a copper foil which has already been torn or a rolled copper foil may be used. Further, the metal layer different from the removal condition of the holder and the other metal layer different from the removal condition of the metal layer are gold, nickel, solder, gold and copper, nickel and copper, etc. In the case of two or more types, the removal condition of the metal facing the holder needs to be different from that of the holder. The metal layer that can be removed together with the holding body is preferably a metal of the same quality as the holding body, and the thickness is about 3 μm as long as it can fill a slight flaw, dent, or fill in the holding body.

As the adhesive, an epoxy resin adhesive,
Acrylic-modified resin-based or polyimide resin-based adhesives can be used, and these can be applied by roll coating, dip coating, curtain coating, or the like. Further, those obtained by film-forming these adhesives can also be used, and epoxy adhesive films such as G604 (trade name, manufactured by Hitachi Chemical Co., Ltd.),
An acrylic-modified resin film such as Pyrarax (manufactured by DuPont, trade name) or a polyimide adhesive film such as AS-2210 (manufactured by Hitachi Chemical Co., Ltd.) can be used. These adhesive films are adhered to the circuit-formed surface of a conductive support having a circuit pattern formed by plating.
Must be on stage. The B stage in the present invention is a state in which it is attached to the surface of the holding body on which the circuit pattern is formed, and it has no adhesiveness at 40 ° C. or lower,
Adhesive strength of 0.8 kgf / cm due to the subsequent multi-layered adhesion
^A semi-cured state that can give ² or more. Such a B-stage state method is carried out by heating at a temperature and for a time at which the resin does not completely cure like ordinary resins. This degree is usually obtained experimentally. Further, in the step of heating and pressurizing to laminate and integrate, the flow rate of the adhesive layer of the B stage is 200 with respect to the surface direction of the substrate.
It is preferably less than μm. When this flow amount is large, it spreads on the wiring conductor of another wiring board when it is pressurized and heated, and the area to be connected by plating becomes small, thus lowering the connection reliability.

[0017]

In the method according to the present invention, since the adhesive is used in the state of B stage, it is easy to make a hole, and it is possible to adhere it to another wiring board by subsequent pressurizing and heating. Furthermore, since a fine wiring pattern can be formed by a manufacturing method in which a conductor circuit to be a surface pattern is embedded in an insulating material, it is possible to achieve a two-dimensional high density and significantly improve the wiring accommodation amount.

[0018]

【Example】

Example 1 As shown in FIG. 1 (a), after polishing a stainless steel surface, copper sulfate plating with a thickness of 20 μm was performed on the entire surface (shown in FIG. 1 (b)). Next, after polishing the copper surface with sandpaper, a photoresist is laminated with a roll laminator, a positive mask is applied, ultraviolet rays are irradiated, and the film is developed with a developing solution. As shown in FIG. A pattern was formed. Subsequently, copper plating is performed to a thickness of 3 μm, flaws formed by polishing are filled, gold plating is performed to a thickness of 1 μm, copper sulfate plating is performed to 30 μm, and the resist is removed with a resist remover to remove the circuit pattern. Was formed (as shown in FIG. 1 (d)). Next, the stainless steel plate is subjected to black oxidation treatment, and G604 (manufactured by Hitachi Chemical Co., Ltd.), which is an adhesive film on the circuit pattern forming surface.
Paste, pressure 10kgf / cm ² After heating for 7 minutes at 150 ° C. for B stage (shown in FIG. 1E), the copper foil having the circuit pattern formed thereon was peeled off from the stainless steel plate (shown in FIG. 1F). . Then, Fig. 1
As shown in (g), a numerically controlled drill machine is used to make holes at the connection points according to the circuit pattern. At this time, the smallest hole diameter was 0.25 mm. Subsequently, the substrate having the holes is overlaid on the adhesive layer side so that another inner layer plate as shown in FIG. 1 (h) is in contact, and the pressure is 40 kgf / cm ² Then, the layers were integrated by heating under pressure at 170 ° C. for 45 minutes (shown in FIG. 1 (i)). Then, a hole is formed through the laminated plates (shown in FIG. 1 (j)),
Copper plating was performed on the entire surface (shown in FIG. 1 (k)). Subsequently, an etching resist was formed at a required position, the surface copper was removed by etching until the embedded gold plating was exposed, and a desired wiring pattern as shown in FIG. 1L was embedded in the substrate. A multilayer printed wiring board was manufactured.

Example 2 As shown in FIG. 2 (a), after polishing the stainless steel surface, copper sulfate plating with a thickness of 20 μm was performed on the entire surface (shown in FIG. 2 (b)). Next, after polishing the copper surface with sandpaper, a photoresist is laminated by a roll laminator, a positive mask is applied, and ultraviolet rays are radiated, followed by development with a developing solution. As shown in FIG. A pattern was formed. Subsequently, gold plating was performed to a thickness of 1 μm, copper sulfate plating was further performed to 30 μm, and the resist was removed with a resist remover to form a circuit pattern (FIG. 2).
It shows in (d). ). Next, the stainless plate is subjected to black oxidation treatment, a G604 (Hitachi Chemical Co., Ltd., trade name) layer, which is an adhesive film, is provided on the circuit pattern forming surface, and the pressure is 10 kgf / cm ² at 150 ° C. for 7 minutes. After heating to the B stage (shown in FIG. 2E), the copper foil having the circuit pattern formed thereon was peeled off from the stainless steel plate (shown in FIG. 2F). Subsequently, as shown in FIG. 2G, a numerically controlled drill machine is used to make holes at the connection points in accordance with the circuit pattern. At this time, the smallest hole diameter was 0.25 mm. Subsequently, the substrate having the holes is laminated on the adhesive layer side so that another inner layer plate as shown in FIG. i)). The lamination conditions at this time were such that the pressure was 40 kgf / cm ² and 170 ° C. for 45 minutes. Subsequently, the surface of this laminated plate was plated with copper having a thickness of 15 μm (shown in FIG. 2 (j)). Next, an etching resist was formed in a required portion, and copper on the surface was removed by etching until the built-in gold plating was exposed to form a circuit conductor (shown in FIG. 2 (k)). The wiring board manufactured in this manner is separately superposed so as to come into contact with the adhesive layer side of the substrate manufactured in the same step as in FIGS. 2A to 2G,
The layers were integrated by heating under pressure (shown in FIG. 2 (l)).
The lamination conditions at this time are pressure 40kgf / cm ² , At 170 ° C 4
It was 5 minutes. Such multilayering is repeated, and after the final lamination, an etching resist is formed, and the copper on the surface is removed by etching until the embedded gold-plated circuit pattern is exposed, as shown in FIG. 2 (m). A multilayer printed wiring board in which a desired wiring pattern was embedded in a substrate was manufactured.

[0020]

As described above, according to the present invention, it is possible to provide a simple method for producing a multilayer printed wiring board which is excellent in wiring density and achieves the following advantages. (1) Since a fine circuit pattern is formed in advance and then laminated, an inspection can be performed before lamination to improve the yield, and a via hole is drilled according to the circuit pattern before lamination, so that the position between the surface layer circuit pattern and the hole is determined. Accuracy is improved. (2) Since the via holes are drilled before the multi-layered bonding, the circuit pattern of the inner layer substrate can be confirmed from the drilled holes, and the interlayer position accuracy is improved. (3) When manufacturing a multilayer printed wiring board for thin products,
Since the surface circuit pattern is embedded in the substrate and protected by the metal layer that is corrosion resistant to the etching solution, the line width accuracy is high regardless of the irregularities and undulations of the substrate.

[Brief description of drawings]

1A to 1L are cross-sectional views in each step for explaining an embodiment of the present invention.

2A to 2M are cross-sectional views in each step for explaining another embodiment of the present invention.

[Explanation of symbols]

1. Stainless plate 2. Copper sulfate plating 3. Resist pattern 4. Plating circuit pattern 5. Adhesive 6. Holes that are non-through holes 7. Inner layer plate 8. Non-through hole 9. Through hole 10. Plated copper 11. Circuit conductor formed by etching resist 12. Built-in circuit pattern

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazushi Yamagishi 1500 Ogawa, Shimodate City, Ibaraki Prefecture Hitachi Chemical Co., Ltd. Shimodate factory (72) Inventor Yoshihiro Tamura 1500 Ogawa, Shimodate City, Ibaraki Hitachi Chemical Co., Ltd. Shimodate Factory (72) Inventor Kenichi Kawata 1500 Ogawa, Shimodate City, Ibaraki Prefecture Hitachi Chemical Co., Ltd. Shimodate Factory

Claims (4)

[Claims] 1. A method for manufacturing a multilayer printed wiring board, comprising the following steps. (A) A plating resist is formed in a desired shape on the surface of a conductive support, and a metal layer A different from the removal condition of the support and a metal layer B different from the removal condition of the metal layer A are plated. Forming a desired circuit pattern and removing the plating resist; (b) providing an adhesive layer on the surface of the holding body on which the circuit pattern is formed, and using this as an adhesive layer B stage (c) Step of forming a hole in the substrate (d) Step of stacking the holed substrate on the adhesive layer side so that another substrate is in contact with the substrate, pressurizing and heating to integrate the layers (e) The integrated layers Forming a conductor circuit on a required portion of the formed substrate and removing the holder until the circuit pattern formed by the plating is exposed. 2. A method for manufacturing a multilayer printed wiring board, comprising the following steps. (A) A plating resist is formed in a desired shape on the surface of a conductive support, and a metal layer A different from the removal condition of the support and a metal layer B different from the removal condition of the metal layer A are plated. Forming a desired circuit pattern and removing the plating resist; (b) providing an adhesive layer on the surface of the holding body on which the circuit pattern is formed, and using this as an adhesive layer B stage (c) Step of forming a hole in the substrate (d) Step of stacking the holed substrate on the adhesive layer side so that another substrate is in contact with the substrate, pressurizing and heating to integrate the layers (e) The integrated layers Forming a conductor circuit on a necessary portion of the formed substrate and removing the holding body until the circuit pattern formed by the plating is exposed. (F) Forming a desired shape on the surface of another holding body having conductivity. Shape plating resist A step of forming a desired circuit pattern by plating a metal layer C different from the removal conditions of the other holders and a metal layer D different from the removal conditions of the metal layer C, and removing the plating resist (g) A step of providing an adhesive layer on the surface of the other holding body on which a circuit pattern is formed and using this adhesive layer as a B stage (h) making a hole in the other substrate (i) making the hole The other substrate is superposed on the adhesive layer side so that the substrate manufactured in the step (e) comes into contact with the adhesive layer side,
Step of heating and pressurizing to laminate and integrate (j) Steps of repeating the above steps (f) to (i) to form multiple layers, if necessary 3. In the step of forming a circuit pattern on the surface of a holder, a plating resist is formed in a desired shape on the surface of the holder, and a first metal layer E that can be removed together with the holder is formed by plating. A second metal layer comprising a metal layer F different from the removal condition of the holder and a metal layer G different from the removal condition of the metal layer F is formed by plating, and the plating resist is removed. The method for manufacturing a multilayer printed wiring board according to claim 1 or 2. 4. An adhesive having a flow rate of the adhesive layer of B stage of less than 200 μm with respect to the surface direction of the substrate is used in the step of laminating and integrating by heating under pressure. 4. The method for manufacturing a multilayer printed wiring board according to any one of 3 to 3.