JP2009130049A - Multilayer printed circuit board and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multilayer printed circuit board having improved interlayer connection reliability, and to provide a method of manufacturing the multilayer printed circuit board. <P>SOLUTION: In the multilayer printed circuit board 10, a plurality of first resin films 15, having a through-hole 11, a conductor pattern 12 formed on both the surfaces, and a conductive through-hole 14 integrally formed with the conductor pattern 12 on the inner wall of the through-hole, and a second resin film 22 that has a via hole 21 and does not have any conductor patterns on both the surfaces overlap mutually. Conductive paste 23 filled into the via hole 21 is subjected to intermetallic combination with two conductor patterns 12 opposing between two adjacent first resin films 15. The conductor patterns 12 on both the surfaces of each resin film 15 are electrically connected by the conductive through-hole 14, and two conductor patterns 12 opposing between the two adjacent first resin films 15 are electrically connected by the conductive paste 23. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

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

  Conventionally, as a method for manufacturing a multilayer printed board, for example, there are methods for manufacturing 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, the single-sided conductor pattern film has a bottomed via hole having a conductive pattern as a bottom surface, 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 JP 2003-86948 A

  By the way, in the prior arts disclosed in Patent Documents 1 and 2, in any of the prior arts, only the conductive paste in the via hole is used for the interlayer connection between the conductor pattern layers. Is difficult to achieve, and the interlayer connection reliability is low.

  When only the conductive paste is used for interlayer connection, it is difficult to control the temperature and pressure of the heat fusion press, and it is difficult to electrically connect all interlayer connections. In particular, when a thermoplastic resin is used, 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 thereof is to provide a multilayer printed board having high interlayer connection reliability and a method for manufacturing the same.

  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 the through hole, the conductor pattern formed on both sides, and the inner wall of the through hole. A plurality of resin films each having a first conductor are overlapped, and between the two adjacent resin films of the plurality of resin films, a second metal pattern and two metal conductors facing each other are coupled. A conductor is provided.

  According to this configuration, the conductor patterns on both sides of each resin film are electrically connected by the first conductor, and two conductor patterns facing each other between two adjacent resin films among the plurality of resin films are the first. The two conductors are electrically connected. In this way, the first conductor (conductive through hole) formed on the inner wall of the through hole and the second conductor that is bonded between the two conductive patterns facing each other between the two adjacent resin films are connected to each other between the layers. Since the structure is used for connection, the interlayer connection reliability is high. Moreover, since the conductor pattern on both surfaces of the resin film and the first conductor on the inner wall of the through hole are integrally formed, the interlayer connection reliability is high.

  A multilayer printed circuit board according to a second aspect of the present invention includes a plurality of through holes, a conductor pattern formed on both sides, and a first conductor formed integrally with the conductor pattern on the inner wall of the through hole. The first resin film and the second resin film having via holes and having no conductor pattern on both sides are alternately stacked, and the conductive paste or metal powder filled in the via holes is the plurality of the plurality of the resin films. Two conductive patterns facing each other between two adjacent first resin films among the first resin films are bonded to each other between metals.

  According to this configuration, the conductive patterns on both sides of each resin film are electrically connected by the first conductor, and the two adjacent first resin films are opposed to each other among the plurality of first resin films. Two conductor patterns are electrically connected by a conductive paste or metal powder. In this way, the first conductor formed on the inner wall of the through hole, the two conductive patterns facing each other between the two adjacent first resin films, and the conductive paste or metal powder bonded between the metals are connected between the layers. Therefore, the interlayer connection reliability is high. Moreover, since the conductor pattern on both surfaces of the resin film and the first conductor on the inner wall of the through hole are integrally formed, the interlayer connection reliability is high.

  The multilayer printed board according to the invention described in claim 3 is characterized in that the conductor pattern and the first conductor each include a base metal layer and a conductor layer formed on the base metal layer. It is formed in the said conductor layer, It is characterized by the above-mentioned.

  According to this configuration, since the conductor pattern and the first conductor have a two-layer structure including the base metal layer and the conductor layer, the adhesion between the conductor layer and the resin film is improved, so that the interlayer connection reliability Is further improved.

  The multilayer printed circuit board according to claim 4, wherein the base metal layer is formed of a Ni—P alloy having P of 2 to 6% and a thickness of 0.05 to 0.5 μm, and the conductor layer Is made of Cu.

  The multilayer printed board according to the invention described in claim 5 is characterized in that the first 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.

  According to this configuration, there is no need to use an adhesive layer between the first resin film and the conductors formed on both surfaces and the inner wall of the through hole, and the number of steps can be reduced accordingly.

  The multilayer printed board according to the invention described in claim 6 is characterized in that the first resin film is made of a polyarylketone resin and an amorphous polyetherimide.

  The multilayer printed circuit board according to the invention described in claim 7 is characterized in that the first resin film is a film in which crystals have optical anisotropy.

  The multilayer printed circuit board according to an eighth aspect of the invention is characterized in that the conductive paste is made of metal powder containing at least Sn, Cu, and Ag.

  In order to solve the above-mentioned problem, a manufacturing method of a multilayer printed circuit board according to claim 9 includes a through hole, a conductor pattern formed on both sides, and an integral part of the conductor pattern on an inner wall of the through hole. A step of producing a resin film having a formed first conductor, and a second conductor made of a conductive paste or metal powder are interposed between the conductive patterns of two adjacent resin films, so that a plurality of Stacking resin films, and stacking these laminates by a heat fusion press.

  According to this configuration, the conductor patterns on both sides of each resin film are electrically connected by the first conductor, and two conductor patterns facing each other between two adjacent resin films among the plurality of resin films are the first. The two conductors are electrically connected. As described above, the first conductor formed on the inner wall of the through hole, the two conductive patterns facing each other between the two adjacent resin films, and the conductive paste or metal powder bonded between the metals are used for interlayer connection. Therefore, the interlayer connection reliability is high. Moreover, since the conductor pattern on both surfaces of the resin film and the first conductor on the inner wall of the through hole are integrally formed, the interlayer connection reliability is high. Furthermore, since the first conductors and the conductive paste that take the interlayer connection are alternately laminated, the pressure on the conductive paste tends to be uniform at the time of heat fusion pressing, and the interlayer connection reliability is high.

  In order to solve the above problems, a method for manufacturing a multilayer printed board according to claim 10 includes a through hole, a conductor pattern formed on both sides, and a conductor of the conductor pattern on an inner wall of the through hole. A step of producing a first resin film having a first conductor formed integrally; a step of producing a second resin film having via holes and having no conductor pattern on both sides; and an opening end of the via hole After the first resin film and the second resin film are heat-sealed so as to be in contact with the conductor pattern, a unit unit is formed, and the via hole is filled with a conductive paste or metal powder And a step of stacking a plurality of the unit units, and stacking these laminates by a heat fusion press.

  According to this configuration, the conductive patterns on both sides of each resin film are electrically connected by the first conductor, and the two adjacent first resin films are opposed to each other among the plurality of first resin films. Two conductor patterns are electrically connected by a conductive paste or metal powder. In this way, the first conductor (conductive through hole) formed on the inner wall of the through hole and the two conductive patterns facing each other between the two adjacent first resin films and the conductive paste or metal powder bonded between the metals. Are used for the interlayer connection, and thus the interlayer connection reliability is high. Moreover, since the conductor pattern on both surfaces of the first resin film and the first conductor on the inner wall of the through hole are integrally formed, the interlayer connection reliability is high. Furthermore, since the first conductors and the conductive paste that take the interlayer connection are alternately laminated, the pressure on the conductive paste tends to be uniform at the time of heat fusion pressing, and the interlayer connection reliability is high.

  In the method for producing a multilayer printed circuit board according to claim 11, in the step of producing the first resin film, a base metal layer is formed by electroless plating on both surfaces 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 conductive patterns on both sides of the first resin film are formed on the conductive layer.

  According to this configuration, the conductor pattern and the first conductor have a two-layer structure including the base metal layer and the conductor layer, thereby improving the adhesion of the conductor layer. Thereby, the interlayer connection reliability is further improved. Moreover, since the base metal layer is formed by electroless plating, the conductor thickness of the conductor pattern and the first conductor 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 conductor pattern and the first conductor is uniform.

  According to the present invention, a multilayer printed board having high interlayer connection reliability can be obtained.

  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 a partial cross-sectional view showing an enlarged part of FIG. 3 to 6 are process diagrams for explaining a method of manufacturing a multilayer printed board.

  A multilayer printed board 10 shown in FIG. 1 is formed as a six-layer multilayer printed board as an example. The multilayer printed circuit board 10 includes a through hole 11, a conductor pattern 12 formed on both surfaces, and a conductive through hole 14 that is a first conductor formed integrally with the conductor pattern 12 on the inner wall of the through hole 11. The first resin film 15 and the second resin film 22 having via holes 21 and having no conductor pattern on both surfaces are alternately stacked. The first resin film 15 and the second resin film 22 are alternately overlapped so that the first resin film 15 is located on both sides.

  Further, in the multilayer printed circuit board 10, the conductive paste 23, which is the second conductor filled in the via hole 21, faces between the two adjacent first resin films 15, 15 of the three resin films 2. The two conductor patterns 12, 12 are bonded to each other. As a result, the two conductive patterns 12, 12 facing each other between the two adjacent first resin films 15, 15 are electrically connected and mechanically coupled by the conductive paste 23.

  Furthermore, the multilayer printed circuit board 10 includes a resist film 41 that covers the entire one conductor pattern 12 of the first resin films 15 and 15 on both sides thereof, and a resist film 42 that covers the entire other conductor pattern 12. Yes. In the resist films 41 and 42, through holes 41a and 42a for exposing a part of the conductor pattern 12 (a portion to be an electrode) are formed, respectively.

  The 1st resin film 15, the 2nd resin film 22, and the resist films 41 and 42 are comprised by the same film base material, for example. 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 conductor pattern 12 and the conductive through hole 14 of each first resin film 15 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 13 b of the conductor 13 on both surfaces of each first resin film 15.

  In the multilayer printed circuit board 10 having the above configuration, three first resin films 15 and two second resin films 22 are alternately stacked as shown in FIG. 1, and resist films 41 and 42 are formed on both sides. In the arranged state, it is produced by a heat fusion press. The first resin film 15, the second resin film 22, and the resist films 41 and 42 adjacent to each other are fused together and filled into the through hole 21 of the second resin film 22 by this heat fusion press. The conductive paste 23 is cured. As a result, the two conductive patterns 12, 12 facing each other are electrically connected and mechanically coupled by the conductive paste 23.

  In the multilayer printed circuit board 10, the conductive through hole 14 and the conductive paste 23 formed on the inner wall of the through hole 11 are used for interlayer connection.

  Next, a method for manufacturing the multilayer printed circuit board 10 having the above configuration will be described with reference to FIGS.

(1) First, the 1st resin film 15 which has the through hole 11, the conductor pattern 12 formed in both surfaces, and the conductive through hole 14 integrally formed with the conductor of the conductor pattern 12 in the inner wall of the through hole 11. The process of producing is implemented.

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

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

  Next, the conductive pattern 12 is formed in the conductor layer 13b (refer FIG. 2) of the conductor 13 in both surfaces of the 1st resin film 15 among the conductors 13 (refer FIG.3 (D)).

(2) Next, the process of producing the 2nd resin film 22 which has the via hole 21 and does not have a conductor pattern on both surfaces is implemented.

    In this step, via holes 21 are formed in the first resin film 22 shown in FIG. 4A by drilling (see FIG. 4B).

(3) Next, as shown in FIG. 5A, the first resin film 15 and the second resin film 22 are heat-sealed so that the opening end of the via hole 21 is in contact with the conductor pattern 12. A step of producing a unit unit is performed.

  Alternatively, the via hole 21 may be formed by first heat-sealing the resin film 22 to the first resin film 15 and then drilling.

(4) Next, the conductive paste 23 is filled in the via hole 21 (see FIG. 5B).
(5) Next, a plurality of unit units 30 are stacked, and a process of stacking these stacked bodies by a heat fusion press is performed.

  In this step, the resist film 42, the first resin film 15, the two unit units 30 and 17, and the resist film 41 are stacked in the order shown in FIG. 6, and these stacked bodies are stacked by a heat fusion press. Thereby, the multilayer printed circuit board 10 shown in FIG. 1 is completed.

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

  The conductive patterns 12 on both surfaces of each resin film 15 are electrically connected by the conductive through holes 14 that are the first conductors, and two adjacent first resin films among the plurality of first resin films 15 Two conductive patterns 12 facing each other are electrically connected by a conductive paste 23. Thus, the conductive paste for electrically connecting the conductive through hole 14 formed in the inner wall of the through hole 11 and the two conductive patterns 12 and 12 facing each other between the two adjacent first resin films 15 and 15. 23 is used for the interlayer connection, so the interlayer connection reliability is high.

  Moreover, since the conductive pattern 12 on both surfaces of the first resin film 15 and the conductive through hole 14 on the inner wall of the through hole 11 are integrally formed, the interlayer connection reliability is high. Therefore, the multilayer printed circuit board 10 with high interlayer connection reliability can be obtained.

  ○ 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 at the same time, the connection reliability is high and the conductor thickness of the conductive pattern 12 and the conductive through hole 14 is uniform.
(Example)
<Method for producing resin film 15>
A liquid crystal polymer film (Vecstar (registered trademark) CT-50N manufactured by Kuraray Co., Ltd.) having a thickness of 50 μm was used as the first resin film 15.

The 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.

  Irregularities were formed on the surface by dipping in a 10 N potassium hydroxide solution at 80 ° C. for 15 to 30 minutes. 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.

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

A film in which through holes and both surfaces of the film were made conductive was manufactured by sequentially performing a conditioner treatment, an electroless plating treatment of a nickel phosphorus alloy, a heat treatment, and an electroplating treatment of copper.
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 (Ni) -phosphorus (P) plating was performed on both surfaces of the first resin film 15. A phosphor having a phosphorus concentration of 2 to 6% was selected from commercially available nickel-phosphorous plating solutions. 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 (Meldex Co., Ltd.) or Top Nicolo LPH-LF (Okuno Pharmaceutical Co., Ltd.) 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 Eugelite 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. In addition, the semi-additive method in which the electrolytic copper plating thickness (conductor thickness) is set to 2 to 3 microns, the plating resist is formed, and then the conductive copper plating is performed on the conductor pattern portion can be used for finer circuit formation I do not care.

<Method for Manufacturing Multilayer Printed Circuit Board 10>
The 1st resin film 15 and the 2nd resin film 22 were piled up, and the heat fusion press was performed in the range of the press temperature of 150-350 degreeC, and the range of the press pressure of 0.5-10 MPa.

  In the example, the first resin film 15 and the second resin film 22 were fused at 1 MPa and 220 ° C.

  Next, the conductive paste 23 was applied to the via hole 21 of the second resin film 22 by screen printing.

  Next, a plurality of unit units 30 in which the first resin film 15 and the second resin film 22 were fused were overlapped, and a batch heat fusion press was performed.

  The pressing temperature was in the range of 150 to 350 ° C. and the pressing pressure in the range of 0.5 to 10 MPa. By this pressing, the resin films 15 and 22 are fused together, the conductive paste 23 filled in the via hole 21 of the resin film 22 is cured, and the conductive paste 23 and the conductor pattern 12 of the resin film 15 are electrically connected. It was. As the conductive paste 23, Dotite XA-824 made by Fujikura Kasei Co., Ltd. was used as an Ag paste. The conductive paste 23 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 (BIAC (registered trademark) BC manufactured by Japan Gore-Tex 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 base material.

  In Example 4, 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 5, 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 a film substrate.

  In Example 6, PEEK / PEI (IBUKI (registered trademark) manufactured by Mitsubishi Plastics, Inc.) having a thickness of 50 μm was used as a film substrate.

  In Examples 2 to 6, the multilayer substrate was produced in the same manner as in Example 1, and the pressing pressure and temperature were performed under the conditions shown in Table 1 below.

（比較例）
比較例１〜６では、銅箔と樹脂フィルムを張り合わせた片面積層板（片面導体パターンフィルム）、および、両面積層板（両面導体パターンフィルム）を用い、層間接続には、ブラインドビアホールに導電ペーストを充填したものを熱融着プレスして多層プリント基板を作製した。導電ペーストは実施例と同じものを用いた。各比較例で用いたフィルム、プレス圧力、プレス温度は下記の表２による。フィルムは実施例と同じ型番で厚さのものを使用した。

(Comparative example)
In Comparative Examples 1 to 6, a single-area layer board (single-sided conductor pattern film) and a double-sided laminated board (double-sided conductor pattern film) bonded with copper foil and a resin film were used, and a conductive paste was applied to the blind via hole for interlayer connection. The filled one was heat fusion pressed to produce a multilayer printed circuit board. The same conductive paste as in the example was used. The film, press pressure, and press temperature used in each comparative example are shown in Table 2 below. A film having the same model number and thickness as in the example was used.

プレスによる基板変形量の評価：
フィルム厚さを基準にして、融着プレス後の基板厚さの変化を求めた（表１、表２参照）。実施例、比較例では５０ミクロン厚の樹脂フィルムを７枚積層したので、３５０ミクロン厚を基準とし、プレス後のフィルム厚さを測定し、厚さ変形量とした。
接続信頼性の比較：
ＪＩＳ Ｃ ５０１２の付図２．１のＬに準じる導体パターンの６層基板を作製した。ただし、層間接続部の穴径１００ミクロンとし、ランド径は０．５ｍｍ、配線幅は０．３ｍｍとし、スルーホール１１の間隔は７．６２ｍｍとした。実施例の多層プリント基板１０の作製では、導電スルーホール１４の中心位置に対し、導電ペースト２３を充填するビアホール２１の中心位置は１５０ミクロンオフセットした位置となるようにした。一方、比較例では、層間接続をとるための導電ペーストを充填するビアホールは同軸上となるように配置した。

Evaluation of substrate deformation by pressing:
Based on the film thickness, the change in the substrate thickness after the fusion press was determined (see Tables 1 and 2). In the examples and comparative examples, seven 50 micron thick resin films were laminated, so that the thickness after pressing was measured based on the 350 micron thickness as the thickness deformation.
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 11 was 7.62 mm. In the production of the multilayer printed board 10 of the example, the center position of the via hole 21 filled with the conductive paste 23 was set to be offset by 150 microns with respect to the center position of the conductive through hole 14. On the other hand, in the comparative example, the via holes filled with the conductive paste for interlayer connection are arranged so as to be coaxial.

  In the examples, 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.

  Looking at Examples 1 to 6 shown in Table 1 and Comparative Examples 1 to 6 shown in Table 2, according to each of Examples 1 to 6, the following effects can be obtained.

The deformation amount of the press thickness after the fusion press is small.
Through hole connection reliability is high.

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

  In this multilayer printed circuit board 10A, as shown in FIGS. 7 and 8, the conductive paste 23, which is the second conductor that electrically connects and mechanically couples the two opposing conductor patterns 12, 12, is adjacent to the conductive pattern 23. It is applied to either one of the two conductive patterns 12, 12 facing each other between the two resin films 15, 15.

  Thereafter, a resist film 42, a resin film 15 in which the conductive paste 23 is applied on the conductive pattern 12, a resin film 15 in which the conductive paste 23 is applied on the conductive pattern 12, a resin film 15 in which the conductive pattern 12 is not applied, Then, the resist films 41 are sequentially stacked, and these laminates are stacked by a heat fusion press. Thereby, the multilayer printed circuit board 10A shown in FIG. 1 is completed.

  In this multilayer printed circuit board 10A, the conductive pastes 23 are cured by heat fusion press and are bonded to the conductive patterns 12 above and below the metal, so that the conductive patterns 12 and 12 above and below the conductive patterns 23 are formed by the conductive pastes 23. Are electrically connected and mechanically coupled.

  According to 2nd Embodiment comprised as mentioned above, in addition to the said effect produced by the said 1st Embodiment, there exist the following effects.

  The conductive patterns 12 on both surfaces of each resin film 15 are electrically connected by the conductive through hole 14 that is the first conductor, and two adjacent resin films 15 of the plurality of resin films 15 are opposed to each other. The two conductor patterns 12 are electrically connected by a conductive paste 23 that is a second conductor. As described above, the conductive through hole 14 formed in the inner wall of the through hole 11 and the two conductive patterns 12 facing each other between the two adjacent resin films 15 and the conductive paste 23 bonded between the metals are used for interlayer connection. Due to the configuration, the interlayer connection reliability is high. Further, since the conductive pattern 12 on both surfaces of the resin film 15 and the conductive through hole 14 on the inner wall of the through hole are integrally formed, the interlayer connection reliability is high.

  Since the conductive paste 23 for making interlayer connection is applied to one of the two conductive patterns 12, 12 facing each other between the two adjacent resin films 15, 15, the conductive paste in the first embodiment is used. The second resin film 22 having the via hole 21 for accommodating the paste 23 becomes unnecessary. Thereby, the number of parts and processes are reduced, and the manufacturing cost can be reduced.

In addition, this invention can also be changed and embodied as follows.
In each of the above embodiments, the number of laminated resin films 15 is not limited to “3”, and the present invention can be widely applied to a multilayer printed board in which a plurality of resin films 15 are stacked.

  In each of the above-described embodiments, the second is provided between two adjacent resin films of the plurality of resin films 15 to electrically connect and mechanically connect the two opposing conductor patterns 12 and 12. Instead of the conductive paste, which is a conductor, metal powder may be used.

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 1st resin film. (A), (B) is process drawing which shows the preparation procedures of a 2nd resin film. (A), (B) is process drawing which shows the preparation procedure of a unit unit. 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. Sectional drawing which shows the resin film by which the electrically conductive paste was apply | coated on the electrically conductive pattern.

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 hole (first conductor)
15: 1st resin film 21: Via hole 22: 2nd resin film 23: Conductive paste (2nd conductor)
30: Unit unit 41, 42: Resist film 41a, 42a: Through hole

Claims (11)

A plurality of resin films each having a through hole, a conductor pattern formed on both sides, and a first conductor formed integrally with the conductor pattern on the inner wall of the through hole are overlaid,
A multilayer printed circuit board, wherein a second conductor that is metal-to-metal bonded to two opposing conductor patterns is provided between two adjacent resin films of the plurality of resin films. A plurality of first resin films each having a through hole, a conductor pattern formed on both sides, and a first conductor formed integrally with the conductor pattern on the inner wall of the through hole; And the second resin film having no conductor pattern are alternately stacked,
The conductive paste or metal powder filled in the via hole is metal-bonded to the two conductive patterns facing each other between the two adjacent first resin films of the plurality of first resin films. A multilayer printed circuit board characterized by comprising:   The conductor pattern and the first conductor each include a base metal layer and a conductor layer formed on the base metal layer, and the conductor pattern is formed on the conductor layer. Item 3. The multilayer printed circuit board according to Item 1 or 2.   The base metal layer is made of a Ni-P alloy having a P content of 2 to 6% and a thickness of 0.05 to 0.5 microns, and the conductor layer is made of Cu. Item 4. The multilayer printed circuit board according to item 3.   5. The multilayer printed circuit board according to claim 1, wherein the first 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 claim 1, wherein the first resin film is made of a polyaryl ketone resin and an amorphous polyetherimide.   The multilayer printed circuit board according to any one of claims 1 to 4, wherein the first resin film is a film in which crystals have optical anisotropy.   The multilayer printed circuit board according to any one of claims 1 to 7, wherein the conductive paste is made of a metal powder containing at least Sn, Cu, and Ag. Producing a resin film having a through hole, a conductor pattern formed on both sides, and a first conductor formed integrally with the conductor pattern on the inner wall of the through hole;
A step of interposing a second conductor made of conductive paste or metal powder between the conductive patterns of two adjacent resin films, stacking a plurality of the resin films, and stacking these laminates by heat fusion press When,
A method for producing a multilayer printed circuit board, comprising: Producing a first resin film having a through hole, a conductor pattern formed on both surfaces, and a first conductor formed integrally with the conductor of the conductor pattern on the inner wall of the through hole;
Producing a second resin film having via holes and no conductor pattern on both sides;
Producing a unit unit by thermally fusing the first resin film and the second resin film so that the opening end of the via hole is in contact with the conductor pattern;
After filling the via hole with a conductive paste or metal powder, stacking a plurality of the unit units, and laminating these laminates by heat fusion press,
A method for producing a multilayer printed circuit board, comprising:   In the step of producing the first resin film, after forming a base metal layer by electroless plating on both surfaces of the resin film and the inner wall of the through hole, and forming a conductor layer by electroplating on the base metal layer, The method for producing a multilayer printed board according to claim 9 or 10, wherein a conductor pattern on both sides of the first resin film is formed on a conductor layer.

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