JP4415985B2 - Manufacturing method of metal transfer plate - Google Patents

Description

  The present invention relates to a metal transfer plate that can be used in a method for producing a multilayer printed wiring board by transfer onto an insulating substrate.

  In recent years, the development of the electronics field has been remarkable, and with the miniaturization, high-density mounting, and high performance (high speed) of electronic devices, the density of the wiring board itself, that is, the miniaturization of the conductor pattern and high reliability have been demanded. It has been.

In order to form a copper wiring pattern on an insulating substrate, a subtractive method is generally used.
However, there is a problem that the subtractive method cannot be used when the copper wiring pattern is miniaturized.

A semi-additive method is used as an effective means for forming a fine copper wiring pattern.
First, a thin base copper layer for electroplating conduction is formed on an insulating substrate, and then a photoresist mask pattern for plating is formed on the surface of the base copper layer.
Next, a copper plating film is formed on the exposed portion of the mask pattern by electrolytic plating, and the mask pattern is peeled off.
Finally, a copper wiring pattern is formed by removing unnecessary portions of the underlying copper layer by soft etching.
However, when the copper wiring pattern becomes finer, the soft etching process for removing the final base copper layer further thins the copper wiring pattern, which may cause disconnection or peeling. Further, when the width between the copper wiring patterns becomes narrow, it becomes difficult to completely remove the unnecessary underlying copper layer, and thus there is a problem that the insulation reliability between the copper wiring patterns is lowered.

Furthermore, when the copper wiring pattern is formed by the semi-additive method, it is necessary to make the underlying copper layer thin in order to reduce damage to the copper wiring pattern during soft etching.
However, when the underlying copper layer is thin, the thickness of the underlying copper layer is varied and the resistance is increased at the same time, so that there is a problem that the variation of the copper wiring pattern is increased.

As another method, a fine copper wiring pattern can be formed in a process including an electroless plating method.
First, after applying a catalyst for electroless copper plating to the roughened polyimide surface, a mask pattern for plating is formed, and then a copper plating film is formed on the exposed portion of the mask pattern by electroless plating.
Alternatively, first, a 1 to 5 micron film is formed on the exposed portion of the mask pattern by electroless plating, and then electrolytic plating is performed to form a copper plating film.
Finally, the plating mask pattern is peeled off to form a copper wiring pattern.
However, the most problematic problem with this method is the catalyst remaining on the polyimide surface between the copper wiring patterns.
Pd—Sn colloid is a catalyst that is widely used at present.
However, the corrosion resistance of palladium is strong, and it is difficult to remove palladium adhering to the polyimide surface by a normal etching process, and there is a problem that residual palladium deteriorates the insulation between copper wiring patterns.

The problem to be solved by the present invention is that it is difficult to form a fine copper wiring pattern by a subtractive method and a fine copper wiring pattern can be formed by a semi-additive method. The wiring pattern was severely damaged, and the unnecessary underlying copper layer between the copper wiring patterns could not be completely removed, resulting in low insulation reliability between lines.
By solving these problems, it is possible to provide a multilayer printed wiring board having a fine and highly reliable copper wiring pattern.

  The present invention relates to a concave pattern resist forming step for forming a photoresist mask pattern on a metal plate, a concave pattern forming step for forming a concave pattern for forming a copper pattern by etching on the surface of the metal plate, and a photoresist mask. A resist stripping process for concave pattern for stripping a pattern, an insulating layer forming process for forming an insulating layer on the surface of the metal plate by sputtering, and a photoresist mask for removing the insulating layer on the surface of the concave pattern on the surface of the metal plate It consists of an insulating layer resist forming step for forming a pattern, an insulating layer removing step for removing the insulating layer on the surface of the concave pattern on the surface of the metal plate by etching, and an insulating layer resist removing step for removing the photoresist mask pattern. A metal transfer plate characterized by forming a concave pattern on the surface of the metal plate There is provided a manufacturing method.

  In this method of manufacturing a multilayer printed wiring board in which a copper wiring pattern and a via land are formed on an insulating substrate by a transfer method, a portion other than the concave pattern is included in the concave pattern of the transfer plate covered with an insulating layer. A pattern forming process for forming a required copper wiring pattern and via land, which includes a plating process for forming a plating film, a roughening process for roughening the exposed surface of the plating film, and a transfer process for transferring onto the insulating substrate. A pasting step of attaching a second insulating substrate on the insulating substrate on which the copper wiring pattern and the via land are formed with an adhesive; and a copper wiring by the transfer method on the second insulating substrate. A second transfer process for forming a pattern and a via land; a via formation process for forming a hole for forming a via with a laser; and a photoresist mask pattern for via plating Provided is a multilayer printed wiring board manufacturing method characterized by repeating a resist forming step to be formed, a via forming step for forming a via by plating, and a resist removing step for removing a photoresist mask pattern for via plating as many times as necessary. can do.

  In addition, in a method for manufacturing a multilayer printed wiring board in which a copper wiring pattern and a via land are formed on an insulating substrate by a transfer method, a plating film is formed in the concave pattern of the transfer board in which portions other than the concave pattern are covered with an insulating layer. A pattern forming step for forming a required copper wiring pattern and a via land constituted by a plating step to be formed, a roughening step for roughening an exposed surface of the plating film, and a transfer step for transferring onto the insulating substrate; A pasting step of attaching a second-layer insulating substrate having a hole directly on the via land on the insulating substrate on which the copper wiring pattern and the via land are formed with an adhesive, and the transfer onto the second-layer insulating substrate. A second transfer step of forming a copper wiring pattern and a via land having a hole in the center by a method, and a resist forming a photoresist mask pattern for via plating It is possible to provide a method for manufacturing a multilayer printed wiring board, characterized in that a forming process, a via forming process for forming a via by plating, and a resist peeling process for peeling a photoresist mask pattern for via plating are repeated a required number of times. it can.

  Further, it is possible to provide a method for manufacturing a printed wiring board, wherein the insulating substrate is selected from polyimide and liquid crystal polymer.

Further, it is possible to provide a method for producing a multilayer printed wiring board, wherein the insulating layer is selected from SiO ₂ and Al ₂ O ₃ .

  In addition, it is possible to provide a method for manufacturing a multilayer printed wiring board, wherein the insulating layer has a thickness of 0.01 μm or more.

  In addition, the exposed surface of the plating film formed in the concave pattern on the metal surface by the plating method is roughened, and the surface roughness Rz is 1 μm or more. A manufacturing method can be provided.

  According to the present invention, since the copper wiring pattern is first formed in the concave pattern on the surface of the metal transfer plate and then transferred to the polyimide substrate, the height variation is small and the insulation between lines is excellent. A multilayer printed board having a copper wiring pattern can be formed.

Hereinafter, the present invention will be described in detail with reference to FIGS.
In the case of forming a concave pattern for forming a copper wiring pattern and a via land (FIG. 1), and in the case of forming a concave pattern for forming a copper wiring pattern and a via land having a hole in the center (FIG. 2). Is also described.

In the present invention, first, a photoresist mask pattern for forming a copper wiring pattern and a concave pattern for forming a via land is formed on the surface of a stainless steel plate, which is a metal plate (FIGS. 1A and 2). (1)).
For the metal plate, stainless steel is used because of ease of transfer, cost, etc., but other metal materials may be used.

Next, using FeCl3 as an etching solution, a concave pattern was formed on the surface of the stainless steel plate by etching, and then the photoresist pattern was stripped with a stripping solution (FIGS. 1 (2) and 2 (2)).
The etching solution can be appropriately selected according to the metal material.
In addition, the photoresist can also be appropriately selected according to the metal material, the etching conditions can be appropriately selected according to the photoresist and the metal material, and the stripping solution and the stripping conditions can also be appropriately selected according to the photoresist and the metal material. It is.
The depth of the concave pattern is 0.1 to 100 μm, and preferably 15 μm. The width of the concave pattern is 0.1 to 50 μm.

FIG. 1B shows a concave pattern for forming a copper wiring pattern and a via land.
FIG. 2B shows a copper wiring pattern and a concave pattern for forming a via land having a hole in the center.

Next, an insulating layer is formed on the surface of the stainless steel plate on which the concave pattern is formed by sputtering ((FIG. 1 (3), FIG. 2 (3)).
The thickness of the insulating layer is 0.01 to 5 μm, and preferably 1 μm. When the thickness is 0.01 μm or less, there is a problem that it is difficult to form a layer.

As the insulating layer, SiO ₂ , Al ₂ O ₃ or the like can be used.
The role of this insulating layer is to prevent the plating film from being formed on portions other than the concave pattern during the subsequent plating.
Even if it is other than SiO ₂ and Al ₂ O _3, other materials are possible as long as the plating film is not formed on the portion other than the concave pattern at the time of subsequent plating.

  Next, a resist mask pattern for removing the insulating layer in the concave pattern on the surface of the stainless steel plate is formed by etching (FIGS. 1 (4) and 2 (4)).

Next, the insulating layer in the concave pattern on the surface of the stainless steel plate is removed by etching, and then the photoresist pattern is peeled off with a stripping solution, thereby producing a stainless steel transfer plate for copper wiring pattern and via land transfer. (Fig. 1 (5), Fig. 2 (5)).
The etching solution can be appropriately selected according to the metal material.
In addition, the photoresist can also be appropriately selected according to the metal material, the etching conditions can be appropriately selected according to the photoresist and the metal material, and the stripping solution and the stripping conditions can also be appropriately selected according to the photoresist and the metal material. It is.

FIG. 1 (5) shows a stainless steel transfer plate (first type transfer plate) for transferring copper wiring patterns and via lands.
FIG. 2 (5) shows a stainless steel transfer plate (second-type transfer plate) for transferring a copper wiring pattern and a via land having a hole in the center.

Next, electrolytic copper plating is performed using the first type transfer plate.
At this time, since the portion other than the concave pattern is covered with the insulating layer, the plating film can be formed only in the concave pattern.
A plating film is formed over at a height of 1 to 10 μm (FIG. 3 (1)).
Preferred is 5 μm.
The purpose is to improve the adhesion between the plating film and the insulating substrate in a later transfer step.

Next, the over portion of the copper plating film in the concave pattern is roughened (FIG. 3 (2)).
Its surface roughness Rz is 1 μm or more.
This is because if the thickness is less than 1 μm, the problem of weak adhesion to the insulating substrate occurs.

  Examples of the chemical solution for roughening in the present invention include CPE-900 manufactured by Mitsubishi Gas Chemical Co., Ltd. and Tech SO-G manufactured by Asahi Denka Kogyo Co., Ltd., but are not limited thereto.

Next, by transferring the copper plating film in the concave pattern onto the insulating substrate, the first-layer copper wiring pattern and the via land can be formed on the first-layer insulating substrate (FIG. 3 (3)). .
Moreover, since the copper plating film part which contacts an insulated substrate was roughened, the adhesive force with an insulated substrate is strengthened and peel strength can be improved.

  As the insulating substrate in the present invention, other materials may be used, but polyimide, liquid crystal polymer and the like are preferable.

Next, the surface of the first layer copper wiring pattern and via land is roughened as necessary, and then the second layer insulating substrate is formed on the first layer insulating substrate on which the first layer copper wiring pattern and via land are formed. Is pasted through an adhesive (FIG. 3 (4)).
The roughening process is the same as 0025 and 0026.
The adhesive can be appropriately selected by taking into consideration the adhesiveness between the insulating substrates and the copper between the insulating substrates.

  A second-layer copper wiring pattern and via land can be formed on the second-layer insulating substrate by the same method as in the above-mentioned 0024 to 0027 (FIG. 3 (5)).

Next, a hole for forming a via is formed by penetrating the second via land and the insulating layer directly therebelow with a laser (FIG. 4 (6)).
Lasers with various wavelengths and outputs can be used as long as they can form holes for forming vias.

Next, a photoresist mask pattern for via plating is formed (FIG. 4 (7)).
The purpose is to prevent a plating film from being formed on other copper wiring patterns when performing subsequent via plating.
Therefore, this mask pattern has only a hole in the second layer via land.
Also, the photoresist can be appropriately selected according to the insulating substrate, and the exposure and development conditions can also be appropriately selected according to the photoresist.

  Next, vias can be formed by copper plating, and the first and second copper wiring patterns can be connected through the vias (FIG. 4 (8)).

Finally, a two-layer printed wiring board can be formed by stripping the photoresist mask pattern for via plating with a stripping solution (FIG. 4 (9)).
The stripping solution can also be appropriately selected according to the photoresist and the insulating substrate, and the stripping conditions can also be appropriately selected according to the photoresist.

  If it repeats in this way, a multilayer printed wiring board can be formed.

  Moreover, a multilayer printed wiring board can also be formed in the following steps.

First, a first-layer copper wiring pattern and a via land can be formed on the first-layer insulating substrate by the above-described methods 0024 to 0027 (FIG. 3 (3)).

Next, after roughening the surface of the first-layer copper wiring pattern and via land, an adhesive is applied to the second-layer insulating substrate on the first-layer insulating substrate on which the first-layer copper wiring pattern and via land are formed. Paste through.
This second insulating substrate is patterned in advance and has a hole for forming a via (FIG. 5A).

  Next, by using the second type stainless steel transfer plate, the second layer copper wiring pattern and the via land can be formed on the second layer insulating substrate by the method of 0024 to 0027 (FIG. 5 (2)). .

  Next, a multilayer printed wiring board can be formed by the method of 0032 to 0035.

  This method is characterized in that a pattern for via plating is formed in advance in the central portion of the formed second-layer insulating substrate and via land, so that drilling with a laser and subsequent processing steps can be omitted.

Example 1
First, a photoresist mask pattern 2 for forming a concave pattern for forming a copper wiring pattern and a via land by etching on the surface of a stainless steel plate 1 having a thickness of 1 mm (Photoresist Tokyo Ohka Co., Ltd .: product name PMER P- 6000) (see FIGS. 1 (1) and 2 (1)).

Next, using FeCl 3, concave patterns 3, 4, and 5 having a depth of 15 μm are formed on the surface of the stainless steel plate by etching. The resist pattern was peeled off (see FIGS. 1 (2) and 2 (2)).
Reference numerals 3, 4, and 5 are a copper wiring pattern and a concave pattern for forming a via land and a via land having a hole in the center.

Next, a SiO ₂ insulating layer 6 having a thickness of 1 μm was formed on the surface of the stainless steel plate 1 by sputtering (see FIGS. 1 (3) and 2 (3)).

Next, in order to remove the SiO ₂ insulating layer in the concave pattern on the surface of the stainless steel plate 1, a photoresist pattern 7 (Photoresist Tokyo Ohka Co., Ltd. product name: PMER P-6000) is formed on the SiO ₂ insulating layer. (See FIGS. 1 (4) and 2 (4)).

Next, the SiO ₂ insulating layer in the concave pattern on the surface of the stainless steel plate is removed by etching using hydrofluoric acid, and then the photoresist pattern is removed with a stripping solution (product name: PMER stripping solution PS manufactured by Tokyo Ohka Co., Ltd.). The first type transfer plate 8 (refer to FIG. 1 (5)) and the second type transfer plate 9 (refer to FIG. 2 (5)) can be manufactured by peeling the film.

(Example 2)
By performing electrolytic copper plating using the first type transfer plate, copper wiring patterns 10 and 11 having a height exceeding 2 μm were formed in the concave pattern (see FIG. 3A).

Next, the exposed surfaces of the plating films 10 and 11 were roughened with CPE-900 manufactured by Mitsubishi Gas Chemical Co., Ltd. (see FIG. 3B).
The surface roughness Rz was 1 μm or more.

  Next, the plating film with the exposed surface roughened was transferred onto the polyimide substrate 13 to form a first-layer copper wiring pattern and via land 12 on the first-layer polyimide substrate 13 (FIG. 3 ( 3)).

  Next, the copper wiring pattern and the via land surface are roughened by CPE-900 manufactured by Mitsubishi Gas Chemical Co., Ltd. (surface roughness Rz is 1 μm or more), and then the first layer in which the first copper wiring pattern and the via land are formed. A second-layer polyimide substrate 14 was pasted onto the first polyimide substrate via an adhesive 14 ′ (epoxy adhesive: manufactured by Hitachi Chemical Co., Ltd .: product name AS2700 thickness 25 μm) (see FIG. 3 (4)). ).

  Next, a second-layer copper wiring pattern and a via land 15 were formed on the surface of the second-layer polyimide substrate 14 by the method of 0048 to 0050 (see FIG. 3 (5)).

  Next, a hole 16 for forming a via with a laser was formed (see FIG. 4 (6)).

  Next, a photoresist mask pattern 17 (product name: PMER P-6000, manufactured by Photoresist Tokyo Ohka Co., Ltd.) for via plating was formed (see FIG. 4 (7)).

  Next, a via 18 having a thickness of 25 μm was formed by copper plating (see FIG. 4 (8)).

  Finally, a two-layer printed wiring board was formed by peeling the photoresist mask pattern 17 for via plating with a stripping solution (manufactured by Tokyo Ohka Co., Ltd .: product name PMER stripping solution PS) (FIG. 4 (9)). reference).

  If it repeats in this way, a multilayer printed wiring board can be formed.

(Example 3)
Steps 0048 to 0050 are the same as those in the first embodiment.

Next, the second layer polyimide substrate in which the holes 20 are formed in advance at the via positions with a laser (same as the laser of Example 2) is bonded to the first layer via an adhesive (same as the adhesive of Example 2). The copper wiring pattern and via land were pasted on the first polyimide substrate (see FIG. 5A).

Next, a second-layer copper wiring pattern and a via land can be formed on the second-layer insulating substrate by the method of 0048 to 0050 using the second-type transfer plate (see FIG. 5B).
At that time, since the hole 21 is formed in the middle of the via land, it is not necessary to make a hole with a laser.

  Next, a multilayer printed wiring board can be formed in steps 0054 to 0057.

It is sectional drawing which shows the manufacturing process of the stainless steel transfer plate of this invention. It is sectional drawing which shows the manufacturing process of the stainless steel transfer plate of this invention different from FIG. It is sectional drawing which shows the manufacturing process of the multilayer printed wiring board of this invention. It is sectional drawing which shows the continuation of the manufacturing process of the multilayer printed wiring board of this invention. FIG. 6 is a cross-sectional view showing a manufacturing process of the multilayer printed wiring board of the present invention different from those in FIGS. 4 and 5.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Stainless steel plate 2 Resist mask pattern 3 for forming a concave pattern on the stainless steel surface 4 Concave pattern 4 for forming a copper wiring pattern Recessed pattern 5 for forming a via land For forming a via land having a hole in the center Concave pattern 6 Insulating layer 7 Resist mask pattern 8 for removing the insulating layer in the concave pattern First type transfer plate 9 Second type transfer plate (having a hole in the center of the via land)
10 Plating film (copper wiring pattern)
11 Plating film (via land)
12 First-layer copper wiring pattern and via land 13 First-layer insulating substrate 14 Second-layer insulating substrate 14 'adhesive 15 Second-layer copper wiring pattern and via land 16 Via plating hole 17 formed by laser Via Resist mask pattern 18 for plating 19 Via 19 Two-layer printed wiring board 20 Hole pattern 21 formed on second-layer polyimide substrate Hole for via plating

Claims (2)

A resist pattern forming step for forming a photoresist mask pattern on a metal plate;
A concave pattern forming step of forming a concave pattern for forming a copper pattern by etching on the surface of the metal plate;
A resist stripping process for the concave pattern for stripping the photoresist mask pattern;
An insulating layer forming step of forming an insulating layer on the surface of the metal plate by sputtering;
A resist forming step for an insulating layer for forming a photoresist mask pattern for removing the insulating layer on the surface of the concave pattern on the surface of the metal plate;
An insulating layer removing step of removing the insulating layer on the surface of the concave pattern on the surface of the metal plate by etching;
A resist stripping process for the insulating layer for stripping the photoresist mask pattern,
A method for producing a metal transfer plate, wherein a concave pattern is formed on the surface of the metal plate. The insulating layer is SiO ₂ , Al ₂ O ₃ The method for producing a metal transfer plate according to claim 1, wherein the metal transfer plate is selected from the group consisting of:

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