WO2010070771A1

WO2010070771A1 - Multilayer printed board and method for manufacturing the same

Info

Publication number: WO2010070771A1
Application number: PCT/JP2008/073243
Authority: WO
Inventors: 悟座間; 賢一大賀
Original assignee: 古河電気工業株式会社
Priority date: 2008-12-19
Filing date: 2008-12-19
Publication date: 2010-06-24
Also published as: KR101489034B1; KR20110097961A; CN102257887A; CN102257887B

Abstract

In a multilayer printed board (10), a plurality of resin films (15) overlap each other by having their vertical directions accord with each other. Each resin film is provided with a through hole (11), a conductor pattern (12) formed on one surface, and a conductive through hole (14) integrally formed with the conductor pattern (12) on an inner wall of the through hole. Conductive bodies (23), each of which is intermetallically bonded to the facing conductor pattern (12) and the conductive through hole (14), are arranged between two adjacent resin films among the resin films (15). Interlayer connection between the conductor patterns (12) of resin films is performed through the conductive through hole (14) integrated with the conductor pattern (12), and the conductive body (23), without having another resin film between the two adjacent resin films.

Description

Multilayer printed circuit board and manufacturing method thereof

The present invention relates to a multilayer printed circuit board and a method for manufacturing the same.

Conventionally, as a method for producing a multilayer printed board, for example, there are methods for producing a multilayer board disclosed in Patent Document 1, Patent Document 2, and the like.

In Patent Document 1, a plurality of double-sided substrates with interlayer connection are manufactured, and the plurality of double-sided substrates are stacked via a film-like insulator that has been processed to allow interlayer connection, thereby having electrodes on both sides of the substrate. A method of manufacturing a multilayer substrate is disclosed.

In Patent Document 2, a single-sided conductor pattern film in which a conductor pattern is formed only on one side of a resin film is laminated, and the multilayer film having electrodes on both sides is manufactured by removing the resin film so that the electrodes are exposed. A method is disclosed. Further, in Patent Document 2, except for a single-sided conductor pattern film forming the surface of a multilayer substrate, a bottomed via hole having a conductive pattern as a bottom surface is formed in the single-sided conductor pattern film, and a conductive paste is placed in the bottomed via hole. The technique of making the conductor pattern of adjacent single-sided conductor pattern films conductive through this conductive paste by filling is disclosed. According to this, each conductive pattern layer of the multilayer substrate can be made conductive by the conductive paste in the via hole.
JP 2000-38464 A (Patent No. 3355142) JP 2003-86948 A (Patent No. 3407737)

By the way, in the prior art disclosed in Patent Document 1, another resin film is interposed between two adjacent resin films of a plurality of resin films having a conductor pattern formed on one side. Further, even the conventional technique disclosed in Patent Document 2 has a configuration in which another resin film is interposed between two adjacent resin films of a plurality of resin films having conductor patterns formed on both surfaces. For this reason, the number of parts is large and the manufacturing cost becomes high.

Also, at the time of fusion press, another resin film is easily deformed between two adjacent resin films, it is difficult to electrically connect all the interlayers, and the interlayer connection reliability is low. In particular, when a thermoplastic resin is used for the resin film, the film is likely to be deformed at the time of fusion press, and there is a remarkable problem that the thickness of the multilayer substrate varies.

The present invention has been made in view of such conventional problems, and an object of the present invention is to reduce the number of parts to reduce the manufacturing cost, and to provide a multilayer printed board having high interlayer connection reliability and the manufacturing thereof. It is to provide a method.

In order to solve the above problems, a multilayer printed board according to the invention described in claim 1 is formed integrally with the conductor pattern on a through hole, a conductor pattern formed on one side, and an inner wall of the through hole. A plurality of resin films each having a conductive through hole are stacked in the same vertical direction, and the conductive pattern and the conductive through hole facing each other between two adjacent resin films of the plurality of resin films. Each of the conductors provided between the two land portions is bonded to the metal.

According to this configuration, a plurality of resin films having a conductor pattern and a conductive through hole formed on one side are overlapped in the same vertical direction, and between two adjacent resin films among the plurality of resin films. , The conductor is metal-to-metal coupled with the opposing conductor pattern and conductive through hole. Thereby, between two adjacent resin films, the opposing conductor pattern and the conductive through hole are electrically connected by the conductor and mechanically coupled. In the multilayer printed circuit board integrated in this way, the interlayer connection between the conductive patterns of each resin film can be integrated with the conductive pattern without interposing another resin film between two adjacent resin films. This is done through a through hole and a conductor. Therefore, the number of parts can be reduced to reduce the manufacturing cost, and the interlayer connection reliability is high.

The multilayer printed circuit board according to the invention of claim 2, wherein the conductor pattern and the conductive through hole have a base metal layer and a conductor layer formed on the base metal layer, and the conductor pattern It is formed in a conductor layer.

According to this configuration, since the conductive pattern and the conductive through-hole have a two-layer structure having a base metal layer and a conductive layer, the adhesiveness between the conductive layer and the resin film is improved. Further improve.

According to a third aspect of the present invention, in the multilayer printed circuit board, the base metal layer is formed of a Ni—P alloy having a P of 2 to 6% and a thickness of 0.05 microns, and the conductor layer is made of Cu. It is formed.

The multilayer printed board according to the invention described in claim 4 is characterized in that the conductor is a metal containing Sn.

The multilayer printed board according to the invention described in claim 5 is characterized in that the resin film is a thermoplastic resin having a glass transition point and a melting point of 150 ° C. or higher and 350 ° C. or lower.

The multilayer printed circuit board according to the invention of claim 6 is characterized in that the resin film is a film in which crystals have optical anisotropy.

The multilayer printed circuit board according to the invention of claim 7 is characterized in that the resin film is made of a polyaryl ketone resin and an amorphous polyetherimide.

In order to solve the above problems, a method for manufacturing a multilayer printed board according to an eighth aspect of the invention includes a through hole, a conductor pattern formed on one side, and the conductor pattern integrally formed on an inner wall of the through hole. Forming a resin film each having a formed conductive through hole; forming a plating layer containing Sn on at least one of the conductor pattern of the resin film and a land portion of the conductive through hole; The plating layers containing Sn are interposed between the conductive pattern and the conductive through-holes, which are arranged in the same vertical direction and face each other between the two adjacent resin films. And stacking a plurality of the laminates of the resin films by a heat fusion press, Characterized in that it comprises.

According to this configuration, a plurality of resin films having a conductor pattern and a conductive through hole formed on one side are overlapped in the same vertical direction, and between two adjacent resin films among the plurality of resin films. , A conductor formed by melting a plating layer containing Sn by a heat fusion press is metal-to-metal bonded to the opposing conductor pattern and the land portion of the conductive through hole. Thereby, between two adjacent resin films, the opposing conductor pattern and the land portion of the conductive through hole are electrically connected by the conductor and mechanically coupled. In the multilayer printed circuit board integrated in this way, the interlayer connection between the conductive patterns of each resin film can be integrated with the conductive pattern without interposing another resin film between two adjacent resin films. This is done through a through hole and a conductor. Therefore, the number of parts can be reduced to reduce the manufacturing cost, and the interlayer connection reliability is high.

In order to solve the above-mentioned problem, a manufacturing method of a multilayer printed circuit board according to an invention described in claim 9 includes a through hole, a conductor pattern formed on one side, and an integral part of the conductor pattern on an inner wall of the through hole. A step of producing resin films each having a formed conductive through hole; and a plurality of the resin films having the same vertical direction, and the conductive pattern facing the two adjacent resin films and the conductive pattern And stacking the conductive paste or metal powder with the conductive paste or the metal powder interposed between the land portions of the conductive through-holes, and stacking a plurality of stacked layers of the resin films by a heat fusion press. And

According to this configuration, a plurality of resin films having a conductor pattern and a conductive through hole formed on one side are overlapped in the same vertical direction, and between two adjacent resin films among the plurality of resin films. , The conductor formed by curing the conductive paste metalizes the opposing conductor pattern and conductive through hole. Thereby, between two adjacent resin films, the opposing conductor pattern and the conductive through hole are electrically connected by the conductor and mechanically coupled. In the multilayer printed circuit board integrated in this way, the interlayer connection between the conductive patterns of each resin film can be integrated with the conductive pattern without interposing another resin film between two adjacent resin films. This is done through a through hole and a conductor. Therefore, the number of parts can be reduced to reduce the manufacturing cost, and the interlayer connection reliability is high.

In the method for producing a multilayer printed board according to the invention of claim 10, in the step of producing the resin film, a base metal layer is formed by electroless plating on one side of the resin film and the inner wall of the through hole, A conductive layer is formed on the underlying metal layer by electroplating, and then the conductive pattern is formed on the conductive layer.

According to this configuration, the conductor of the conductor pattern and the conductive through hole have a two-layer structure having the base metal layer and the conductor layer, thereby improving the adhesion of the conductor layer. Thereby, the interlayer connection reliability is further improved. Further, since the base metal layer is formed by electroless plating, the conductor thickness of the conductor pattern and the conductive through hole can be reduced. Thereby, a fine conductor pattern can be formed. On the other hand, in the prior art disclosed in Patent Documents 1 and 2 above, the conductor pattern is formed after the copper foil is fusion-pressed to the film, so the thickness of the copper foil is limited, and the fine processing Not suitable. Furthermore, since the conductor pattern and the conductive through hole are formed at the same time, the connection reliability is high and the conductor thickness of the conductive pattern and the conductive through hole is uniform.

The method for manufacturing a multilayer printed board according to the invention of claim 11 is characterized in that the conductive paste is made of metal powder containing at least Sn, Cu, and Ag.

According to the present invention, it is possible to reduce the number of components and reduce the manufacturing cost, and it is possible to obtain a multilayer printed board having high interlayer connection reliability.

FIG. 3 is a cross-sectional view illustrating a schematic configuration of a part of the multilayer printed board according to the first embodiment. The fragmentary sectional view which expanded and showed a part of FIG. (A) thru | or (D) is process drawing which shows the preparation procedures of a resin film. Explanatory drawing which shows the arrangement | positioning order of each structural member before implementation of a heat-fusion press. Sectional drawing which shows the one part schematic structure of the multilayer printed circuit board concerning 2nd Embodiment. (A) thru | or (D) is process drawing which shows the preparation procedures of a resin film. Explanatory drawing which shows the arrangement | positioning order of each structural member before implementation of a heat-fusion press.

Explanation of symbols

10, 10A: Multilayer printed circuit board 11: Through hole 12: Conductor pattern 13: Conductor 13a: Underlying metal layer 13b: Conductor layer 14: Conductive through

holes

15, 15A, 15B, 15C: Resin films 23, 33: Conductor 23A: Plating layer 33A containing Sn: conductive paste

Next, embodiments embodying the present invention will be described with reference to the drawings. In the description of each embodiment, the same parts are denoted by the same reference numerals, and redundant description is omitted.

(First embodiment)
A multilayer printed circuit board according to the first embodiment will be described with reference to FIGS.

FIG. 1 is a cross-sectional view showing a schematic configuration of a part of the multilayer printed board according to the first embodiment, and FIG. 2 is an enlarged partial cross-sectional view of a part of FIG.

The multilayer printed board 10 shown in FIG. 1 is formed as a three-layer multilayer printed board as an example. The multilayer printed board 10 includes

resin films

15A and 15B each having a through hole 11, a conductor pattern 12 formed on one side, and a conductive through hole 14 formed integrally with the conductor pattern 12 on the inner wall of the through hole 11. , 15C are stacked in the same vertical direction.

In this embodiment, as an example, three

resin films

15A, 15B, and 15C having the same shape are overlapped. These three

resin films

15A, 15B, and 15C are overlaid so that the centers of the conductive through holes 14 coincide.

In the multilayer printed circuit board 10, the conductive through holes 14 of the

resin films

15A, 15B, and 15C are bent from the inner wall of the through hole 11 to the surface opposite to the surface on which the conductor pattern 12 is formed. Each has an extended land 14a (see FIG. 3D).

In this multilayer printed circuit board 10, between the two adjacent resin films of the

resin films

15A, 15B, and 15C, that is, between the

resin films

15A and 15B and between the

resin films

15B and 15C, the opposing conductor pattern 12 and the conductive through Conductors 23 that are metal-to-metal bonded to the land portions 14a of the holes 14 are provided. The conductor 23 is plated with Sn (Sn plating) on the land portion 14a of the conductive through-hole 14 to form a Sn plating layer 23A (see FIG. 3E). The Sn plating layer 23A is melted after pressing. As a result, the conductive pattern 12 and the land portion 14a of the conductive through hole 14 facing each other between the two

adjacent resin films

15A and 15B and between the

resin films

15B and 15C are electrically connected via the conductor 23. Mechanically coupled.

Further, the multilayer printed board 10 includes a resist film 41 that covers the entire conductor pattern 12 of one of the

resin films

15A and 15C (resin film 15C) on both sides thereof, and a land of the conductive through hole 14 on the other side (resin film 15A). And a resist film 42 covering the whole 14a. The resist film 41 is formed with a through hole 41a for exposing a part of the conductor pattern 12 (a portion serving as an electrode). On the other hand, a through hole 42 a for exposing the land 14 a of the conductive through hole 14 is formed in the resist film 42.

Further, the conductor pattern 12 and the conductive through hole 14 of each

resin film

15A, 15B, 15C are formed in one conductor 13. As shown in FIG. 2, the conductor 13 has a base metal layer 13a and a conductor layer 13b formed on the base metal layer 13a. The conductor pattern 12 is formed on the conductor layer 13b on one side of each

resin film

15A, 15B, 15C.

The

resin films

15A, 15B, 15C and the resist

films

41, 42 are made of, for example, the same film base material. As the film base, a general glass cloth base epoxy resin or BT resin may be used, but it is more convenient to use a thermoplastic resin for the film base from the viewpoint of joining a plurality of sheets by a fusion press. It is. Examples of the thermoplastic film include a liquid crystal polymer film, PEEK (Polyetheretherketone), PES (Polyethersulfone), PPE (Polyphenyeneether), PTFE (Polytetrafluoroethylene) and the like. Thermoplastic polyimide may also be used.

The multilayer printed circuit board 10 having the above configuration is integrated by a heat fusion press in a state where the

resin films

15A, 15B, and 15C and the resist

films

41 and 42 are stacked as shown in FIG. By this heat fusion press, Sn in the Sn plating layer 23A is melted to form the conductor 23 which is metal-to-metal bonded to the conductor pattern 12 and the land 14a of the conductive through hole 14. In the multilayer printed circuit board 10 integrated in this way, another conductive film is not interposed between two adjacent resin films of the

resin films

15A, 15B, and 15C, and the conductive patterns 12 of the respective resin films are interposed. The interlayer connection is made through the conductive through hole 14 and the conductor 23 integral with the conductor pattern 12.

Next, a method for manufacturing the multilayer printed circuit board 10 having the above configuration will be described with reference to FIGS. FIG. 3 is a process diagram showing the production procedure of the resin film, and FIG. 4 is an explanatory diagram showing the arrangement order of the respective constituent members before the heat fusion press.

(1) First, resin films 15 </ b> A, 15 </ b> B, 15 </ b> C each having a through hole 11, a conductive pattern 12 formed on one side, and a conductive through hole 14 formed integrally with the conductive pattern 12 on the inner wall of the through hole 11. The process of producing is implemented. Since these

resin films

15A, 15B, and 15C have the same configuration, here, a process of manufacturing the resin film 15A will be described.

In this step, first, a through hole 11 is formed in the resin film 15A shown in FIG. 3A by drilling (see FIG. 3B).

Next, as shown in FIG. 3C, a conductor 13 (having a base metal layer 13a and a conductor layer 13b formed on the base metal layer 13a on both surfaces of the resin film 15A and the inner wall of the through-hole 11). 2). The base metal layer 13a is formed by electroless plating. The conductor layer 13b is formed by electroplating.

Next, the conductor pattern 12 is formed by photoetching or the like on the conductor layer 13b (see FIG. 2) of the conductor 13 on one side of the resin film 15A among the conductors 13 (see FIG. 3D). Further, the conductor on the surface opposite to the conductor pattern 12 of the resin film 15A is removed by etching or the like leaving the land 14a of the conductive through hole 14.

(2) Next, Sn plating (Sn electroplating) is performed on the conductive through holes 14 and the land portions 14a of the

resin films

15B and 15C to form the Sn plating layer 23A. (See FIG. 3E).

For Sn electroplating, Meltex Ronastan EC-J was used as an additive.

Sn electroplating solution 1st tin sulfate 40g / L
Sulfuric acid 100mL / L
Additive Lonastan EC-J
Temperature 20 ° C
Current density 2A / dm ²
Further, not only Sn but Sn—Cu alloy plating (plating bath: Top Freed BR manufactured by Okuno Pharmaceutical Co., Ltd.) may be used. Sn-Ag alloy plating may be used.

Further, the Sn plating method is not limited to electroplating, and displacement plating may be used. In that case, the conductive patterns on both sides were removed by etching, and then immersed in the following plating solution (any of three types) to replace the copper surface to form Sn with a thickness of 2 microns.
Displacement plating:
1st tin chloride 18.8g / L
Sodium cyanide 188 g / L
Sodium hydroxide 22.5g / L
Temperature

Sodium stannate 60g / L
Sodium cyanide 120g / L
Sodium hydroxide 7.5g / L
Temperature 21 ~ 65 ℃

1 st tin chloride 6g / L
Thiourea 55g / L
Tartaric acid 39g / L
Temperature 12-14 ° C

(3) Next, the

resin films

15A, 15B, and 15C are stacked in the same vertical direction as shown in FIG. 4, and the resist film 41 is placed on the resin film 15C, and the resist film 42 is placed under the resin film 15A. A process of stacking the stacked layers and stacking the stacked layers by a heat fusion press is performed.

By the heat sealing press, the conductive paste 23A provided between each conductor pattern 12 and both end portions 25a of the conductive through hole 25 is cured, and the conductive pattern 12 and the end portions 14a of the conductive through hole 14 are connected to the metal. Thus, the multilayer printed circuit board 10 shown in FIG. 1 is completed. Thereby, the multilayer printed circuit board 10 shown in FIG. 1 is completed. The Sn plating layer 23A provided between each conductor pattern 12 and the land portion 14a of the conductive through hole 14 is melted by the heat fusion press, and is bonded to the conductor pattern 12 and the land portion 14a of the conductive through hole between the metals. The conductor (metal containing Sn) 23 is formed.

In addition, after performing the heat fusion press at a temperature lower than the Sn melting point, heat may be applied again to the Sn melting point or higher to melt the Sn to form a metal-bonded conductor.

In the above-described process, an example in which the conductive through holes 14 of the

resin films

15A, 15B, and 15C are coaxial is shown. However, the conductive through holes 14 do not necessarily have to be coaxial. The conductor pattern 12 and the land portion 25a of the conductive through hole 25 of the resin film 22 may be bonded to each other by the conductor 23 between two adjacent resin films.

According to 1st Embodiment comprised as mentioned above, there exist the following effects.
A

resin film

15A, 15B, 15C (a plurality of resin films) having a conductor pattern 12 and a conductive through hole 14 formed on one side is overlapped with each other in two adjacent resin films. Between the resin films, the conductor 23 is metal-to-metal bonded to the opposing conductor pattern 12 and the land portion 14a of the conductive through hole 14. The conductor 23 is obtained by melting Sn of the Sn plating layer 23A at the time of heat fusion pressing or after pressing. Thereby, between the two adjacent resin films, the opposing conductor pattern 12 and the conductive through hole 14 are electrically connected by the conductor 23 and mechanically coupled. In the multilayer printed circuit board 10 integrated in this way, the interlayer connection between the conductive patterns of each resin film is integrated with the conductive pattern 12 without interposing another resin film between two adjacent resin films. The conductive through hole 14 and the conductor 23 are used. Accordingly, it is possible to reduce the number of parts and reduce the manufacturing cost, and it is possible to obtain a multilayer printed board having high interlayer connection reliability.

○ Adhesiveness between the conductor layer 13b and the resin film is improved by forming a single conductor 13 in which the conductor pattern 12 and the conductive through hole 14 are formed into a two-layer structure having a base metal layer 13a and a conductor layer 13b. Therefore, the interlayer connection reliability is further improved.

Since the base metal layer 13a is formed by electroless plating, the conductor thickness of the conductor pattern 12 and the conductive through hole 14 can be reduced. Thereby, the fine conductor pattern 12 can be formed.

○ Since the conductor pattern 12 and the conductive through hole 14 are formed simultaneously, the connection reliability is high and the conductor thickness of the conductive pattern 12 and the conductive through hole 14 is uniform.

(Second Embodiment)
A multilayer printed circuit board 10A according to the second embodiment will be described with reference to FIGS.

Next, a multilayer printed board 10A according to a second embodiment of the present invention will be described with reference to FIGS.

In the multilayer printed circuit board 10 of the first embodiment, the conductor 23 that is metal-to-metal bonded to the conductor pattern 12 and the conductive through hole 14 is obtained by melting Sn of the Sn plating layer 23A.

On the other hand, in the multilayer printed circuit board 10A according to the second embodiment, the conductor 33 (see FIG. 5) bonded to the conductor pattern 12 and the conductive through-hole 14 between the metals is electrically conductive paste 33A (FIG. 6E). ) And FIG. 7) are cured. Thereby, the conductive pattern 12 and the conductive through hole 14 facing each other between two adjacent resin films, that is, between the

resin films

15A and 15B and between the

resin films

15B and 15C are electrically connected via the conductor 33. And mechanically coupled. That is, in this multilayer printed circuit board 10A, the conductive through hole 14 formed in the inner wall of the conductive through hole 11 in the resin film 15 (15A, 15B, 15C) and the conductive through hole 25 in the conductor 33 and the resin film 22 are formed. Used for interlayer connection. The other configuration of the multilayer printed board 10A is the same as that of the multilayer printed board 10 of the first embodiment.

Next, a method for manufacturing the multilayer printed circuit board 10A having the above configuration will be described with reference to FIGS. FIG. 6 is a process diagram showing the procedure for producing the resin film, and FIG. 7 is an explanatory diagram showing the arrangement order of the constituent members before the heat fusion press.

In this case, after the step (1) is performed (see FIGS. 6A to 6D), the steps (2) and (3) are changed to the following steps (2A) and (3A). Will be replaced with

(3A) The conductive paste 33A is interposed between the conductor pattern 12 and both land portions 25a of the second conductive through hole 25 (see FIG. 7E). In this example, the conductive paste 33 </ b> A is applied on both land portions 25 a of the second conductive through holes 25.

(4A) Next, a step of alternately stacking the first resin film 15 and the second resin film 22 is performed.

In this step, the resist film 42, the first resin film 15, the second resin film 22, and the resist film 41 are stacked in the order shown in FIG. Thereby, the multilayer printed circuit board 10A shown in FIG. 1 is completed. The conductive paste 33A provided between each conductor pattern 12 and both land portions 25a of the second conductive through hole 25 is cured by the heat fusion press, and both the conductive pattern 12 and the second conductive through hole 25 are cured. The land portion 25a and the conductor 33 are metal-bonded.

According to the multilayer printed circuit board 10A thus manufactured, the conductive pattern 12 and the conductive through hole 14 facing each other between the two adjacent

first resin films

15 and 15 are electrically connected via the conductor 33. Since it is connected and mechanically coupled, the same effects as those of the first embodiment can be obtained.
Example 1
<Method for Manufacturing Multilayer Printed

Circuit Board

10 or 10A>
Sn plating was performed on the land portion 14 a and the inner wall of the conductive through hole 14. In the Sn plating, an Sn plating layer 23A having a thickness of 1 micron was formed.

Next, the resist film 42, the plurality of resin films, and the resist film 41 were stacked in the order shown in FIG.

The pressing temperature was in the range of 150 to 350 ° C., and the pressing pressure was in the range of 0.5 to 10 MPa. In Example 1 shown in Table 1 below, Sn plated on the land portion 14a is melted by a 1 MPa press at 280 ° C., and the conductive through hole is bonded between the conductor pattern and the metal to establish electrical connection. It was.

In Example 2, a liquid crystal polymer film (BIAC (registered trademark) BC manufactured by Japan Gore-Tex Co., Ltd.) having a thickness of 50 μm was used as the film substrate.

In Example 3, PEEK / PEI (IBUKI (registered trademark) manufactured by Mitsubishi Plastics, Inc.) having a thickness of 50 μm was used as a film substrate. The press pressure and the press temperature were heat-sealed under the conditions shown in Table 1.

In Examples 4 to 6, multilayer substrates were produced using the resin films and press conditions shown in Table 1. Ag paste was used for the connection between the conductive through hole of the second film and the conductor pattern of the first resin film. The conductive paste 33A is applied by screen printing, and the conductive paste 33A is cured by a heat fusion press, and the conductor 33 (see FIG. 6) in which each conductive paste 33A is cured becomes a conductive pattern and a second conductive through. Bonded between hole and metal. As the conductive paste 33A, Dotite XA-824 made by Fujikura Kasei was used as the Ag paste. The pressing conditions are shown in Table 1.

In Examples 7 to 9, multilayer substrates were produced using the resin films and press conditions shown in Table 1. An AgSn paste was used for connection between the conductive through hole of the second film and the conductor pattern of the first resin film. For the details of the paste, the one described in paragraph 0075 of Japanese Patent No. 3473601 was used. A multilayer substrate was produced in the same manner as in Examples 4-6.

A through hole 11 was formed by a carbon dioxide laser.

The through-hole 11 may be not only a carbon dioxide laser but also a UV-YAG laser or an excimer laser with a small diameter. Moreover, you may process the through hole 11 with a mechanical drill.
Film roughening / desmear:
The drilled first resin film 15 was immersed in a strong alkali to dissolve the surface and roughen it.

The surface was dipped in a 10 N potassium hydroxide solution at 80 ° C. for 15 to 30 minutes to form irregularities on the surface. At the same time, the resin smear generated during the formation of the through hole 11 was dissolved and removed, and the inner wall surface of the through hole 11 was also roughened.

The surface of the resin film 15 was plated with Ni—P as a base plating (base metal layer 13a) by electroless plating.

A film metal-clad laminate was manufactured by sequentially performing a conditioner treatment, a nickel-phosphorous alloy electroless plating treatment, a heat treatment, and a copper electroplating treatment.
Electroless plating:
In the conditioner treatment, the surface of the polymer film was washed with an OPC-350 conditioner manufactured by Okuno Pharmaceutical Co., Ltd. Here, an OPC-80 catalyst manufactured by Okuno Pharmaceutical Co., Ltd. was used as a catalyst-providing liquid containing palladium, and an OPC-500 accelerator was used as an activator.

In the electroless plating treatment of the nickel alloy, nickel (P) -phosphorus (P) plating was performed on both surfaces of the first resin film 15. A commercially available nickel-phosphorous plating solution was selected as one having a phosphorus concentration of 5% or less. A nickel nickel thickness of 0.2 microns was formed using chemical nickel EXC manufactured by Okuno Pharmaceutical Co., Ltd.

The plating solution is not limited to this, and Enplate Ni-426 of Meldex Co., Ltd., Top Nicolon LPH-LF of Okuno Pharmaceutical Co., Ltd., etc. may be used.

In order to improve adhesion before copper plating, heat treatment may be performed. Heating was performed at a temperature of 230 to 250 ° C. for 30 seconds to 30 minutes. In this example, heating was performed at 240 ° C. for 3 minutes.
Copper electroplating:
Further, copper electroplating was performed to form a conductor layer 13b of the conductor 13 with a thickness of 1 to 10 microns. In the electroplating process of copper (Cu), copper was formed so that the conductor thickness of the conductor layer 13b was 5 microns. The following copper electroplating solution was used. As an additive, Cubelite TH-RIII manufactured by Sugawara Eugleite Co., Ltd. was used.
Copper sulfate 120 g / L
Sulfuric acid 150 g / L
Concentrated hydrochloric acid 0.125mL / L (as chloride ion)
Production of conductor pattern 12:
The conductor pattern 12 formed a circuit on both surfaces (the conductor layer 13b of the conductor 13) of the first resin film 15 by a subtractive method. A photosensitive resist was applied, exposed to ultraviolet light, and developed. Next, after performing an etching process to form a conductor pattern, the resist was peeled off. For further fine circuit formation, a semi-additive method may be used in which the electrolytic copper plating thickness (conductor thickness) is set to 2 to 3 microns, the plating resist is formed, and then the copper pattern is plated on the conductor pattern portion. I do not care.

<Method for Manufacturing Multilayer Printed Circuit Board 10A>
A conductive paste 33A was applied to both lands 25a of each second conductive through hole 25 by screen printing.

Next, the resist film 42, the first resin film 15, the second resin film 22, and the resist film 41 were stacked in the order shown in FIG.

The pressing temperature was in the range of 150 to 350 ° C., and the pressing pressure was in the range of 0.5 to 10 MPa. By this pressing, the respective conductive pastes 33A are cured, and the conductors 33 in which the respective conductive pastes 33A are cured are bonded to the conductor pattern and the second conductive through holes between the metals.

The conductor 33 and the conductor pattern 12 of the resin film 15 were electrically connected. As the conductive paste 33A, Dotite XA-824 made by Fujikura Kasei was used as the Ag paste. The conductive paste 33A was an AgSn paste. For the details of the paste, the one described in paragraph 0075 of Japanese Patent No. 3473601 was used.

In Example 2, a liquid crystal polymer film (Vecstar (registered trademark) CT-50N manufactured by Kuraray Co., Ltd.) having a thickness of 50 μm was used as a film substrate.

In Example 3, PEEK / PEI (IBUKI (registered trademark) manufactured by Mitsubishi Plastics, Inc.) having a thickness of 50 μm was used as a film substrate.

In Examples 4, 5, 7 and 8, the same film substrate as in Example 2 was used.
In Examples 6 and 9, the same film substrate as in Example 3 was used.

In Examples 2 to 9, the multilayer substrate was produced in the same manner as in Example 1, and the press pressure and temperature were the conditions according to Table 1.

(Comparative example)
As Comparative Examples 1 to 6, a single-area layer plate and a double-sided laminated plate in which a copper foil and a film were bonded together were used, and for the interlayer connection, a blind via hole formed in a film was filled with a conductive paste by heat fusion pressing. A multilayer substrate was prepared. The conditions are shown in Table 2 below.

A method for producing the multilayer substrates of Comparative Examples 1 to 6 is shown below.
A conductor pattern was formed by etching using a copper clad laminate in which a copper foil and a film were heat-sealed. Via holes were formed with a laser.
The conductive paste was applied to the via hole of the film by a screen printing method.
A plurality of films fused with conductive paste embedded were superposed and batch heat fusion press was performed. The pressing temperature was in the range of 230 to 350 ° C. and the pressing pressure in the range of 0.5 to 10 MPa. In this press, the films were fused together, the conductive paste filled in the via holes of the film was cured, and the conductive paste and the conductive pattern of the film were electrically connected. As the conductive paste, Dotite XA-824 from Fujikura Kasei was used as the Ag paste. Moreover, AgSn paste was used as the conductive paste. For the details of the paste, the one described in paragraph 0075 of Japanese Patent No. 3473601 was used.

Connection reliability comparison:
A six-layer substrate having a conductor pattern according to L in Fig. 2.1 of JIS C 5012 was produced. However, the hole diameter of the interlayer connection portion was 100 microns, the land diameter was 0.5 mm, the wiring width was 0.3 mm, and the interval between the through holes was 7.62 mm. In the comparative example, a via hole having a diameter of 100 microns was formed at the same position of the through hole as in the present invention and filled with a conductive paste. In the present invention, a temperature cycle test corresponding to 9.1.3 description condition 1 of JIS C 5012 was performed, and the interlayer connection reliability was investigated. When the resistance value increased by 20% or more with respect to the initial resistance, it was regarded as a connection failure.

According to each of the above embodiments, the following effects were obtained.
The deformation amount of the press thickness after the fusion press is small.
Through hole connection reliability is high.

In addition, this invention can also be changed and embodied as follows.
In each of the above embodiments, the number of resin films stacked is not limited to “3”, and the present invention can be widely applied to a multilayer printed circuit board in which a plurality of resin films are stacked.
In the second embodiment, metal powder may be used instead of the conductive paste 33A.

Claims

A plurality of resin films each having a through hole, a conductive pattern formed on one side, and a conductive through hole formed integrally with the conductive pattern on the inner wall of the through hole are stacked in the same vertical direction. And
Conductors provided between the conductive patterns facing each other between two adjacent resin films of the plurality of resin films and the land portions of the conductive through holes are metal-to-metal bonded. Multilayer printed circuit board.
The conductive pattern and the conductive through-hole have a base metal layer and a conductor layer formed on the base metal layer, and the conductor pattern is formed in the conductor layer. 2. The multilayer printed circuit board according to 1.
The base metal layer is formed of a Ni-P alloy having a P content of 2 to 6% and a thickness of 0.05 microns, and the conductor layer is formed of Cu. Multilayer printed circuit board.
The multilayer printed circuit board according to any one of claims 1 to 3, wherein the conductor is a metal containing Sn.
The multilayer printed circuit board according to any one of claims 1 to 4, wherein the resin film is a thermoplastic resin having a glass transition point and a melting point of 150 ° C or higher and 350 ° C or lower.
The multilayer printed circuit board according to any one of claims 1 to 4, wherein the resin film is a film in which crystals have optical anisotropy.
The multilayer printed circuit board according to any one of claims 1 to 4, wherein the resin film is made of a polyaryl ketone resin and an amorphous polyetherimide.
Producing a resin film each having a through hole, a conductive pattern formed on one side, and a conductive through hole formed integrally with the conductive pattern on the inner wall of the through hole;
Forming a plating layer containing Sn on at least one of the conductor pattern of the resin film and the land portion of the conductive through hole;
The plating layers containing Sn are interposed between the conductive pattern and the conductive through-holes, which are arranged in the same vertical direction and face each other between the two adjacent resin films. And stacking a plurality of the laminates of the resin films by a heat fusion press,
A method for producing a multilayer printed circuit board, comprising:
Producing a resin film each having a through hole, a conductive pattern formed on one side, and a conductive through hole formed integrally with the conductive pattern on the inner wall of the through hole;
Conductive paste or metal powder is placed between the conductive pattern and the land portion of the conductive through-hole, the plurality of the resin films having the same vertical direction and facing each other between the two adjacent resin films. A step of stacking a plurality of the resin films stacked with a heat fusion press, and interposing and stacking;
A method for producing a multilayer printed circuit board, comprising:
In the step of producing the resin film, after forming a base metal layer by electroless plating on one surface of the resin film and the inner wall of the through hole, and forming a conductor layer on the base metal layer by electroplating, the conductor The method for producing a multilayer printed board according to claim 8 or 9, wherein the conductor pattern is formed on a layer.
The method for manufacturing a multilayer printed board according to claim 9, wherein the conductive paste is made of a metal powder containing at least Sn, Cu, and Ag.