JP2007043201A - Method for manufacturing multilayer wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a multilayer wiring board in which high adhesion is achieved between an insulating layer and a wiring layer. <P>SOLUTION: The method comprises a step of sticking a supporting film, in which a metal adhesion layer 50 is provided, to an insulating layer 20 via the metal adhesion layer 50; a step of removing the supporting film, while transferring the metal adhesion layer 50 to the insulating layer 20; a step of forming a via hole 20a in the insulating layer 20 and the metal adhesion layer 50 laminated thereon after the step of removing the supporting film; a step of forming the wiring layer 40 on the metal adhesion layer 50 by forming a resist pattern on the metal adhesion layer 50 and forming a plated film on a non-mask region of the resist pattern, and forming a via 40a in the via hole; a step of removing the resist pattern and removing the metal adhesion layer 50 which is not covered with the wiring layer 40; and a step of performing annealing treatment to the metal adhesion layer 50 and the wiring layer 40 which are laminated. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a multilayer wiring board used in a circuit system of electrical / electronic equipment.

  In recent years, with the demands for downsizing, high performance, and low prices for electronic devices, electronic components have been rapidly mounted at high density. In order to cope with such high-density mounting, a build-up multilayer wiring structure in which wiring is multilayered is often used for a substrate for mounting electronic components.

  In the build-up multilayer wiring structure, wiring layers are embedded between a plurality of insulating layers, and each wiring layer is electrically connected by a via formed in a via hole formed in the insulating layer. As a method for forming a via hole, a method of forming a hole by a photolithography technique using a photosensitive resin with respect to an insulating layer, a method of forming a hole by irradiating a laser, or the like is employed.

  After forming a via hole in the insulating layer, a conductive material is formed on the insulating layer by electroless plating or electroplating, and a wiring pattern is formed by etching the conductive material. By forming a wiring pattern on the insulating layer and then repeating a series of steps from forming the insulating layer to forming the wiring pattern a predetermined number of times, the circuit can be multi-layered and the degree of circuit integration can be increased. it can.

  In a conventional multilayer wiring board having a build-up wiring structure, in order to ensure adhesion between the insulating layer and the wiring layer, the surface of the insulating layer is roughened, and the wiring layer is formed on the insulating layer with a certain degree of unevenness. Were laminated. More specifically, the surface of the outermost insulating layer resin is immersed in a swelling liquid, a roughening liquid, and a neutralizing liquid in order to form irregularities of about 5 μm. Plating and electrolytic copper plating were sequentially applied to form a copper wiring layer. By doing so, adhesion was obtained by a physical anchor effect between the resin layer and the copper wiring layer.

  For example, the following Patent Documents 1 to 3 also disclose a technique aimed at satisfactorily forming a wiring layer on an insulating layer.

JP-A-55-111198 Japanese Patent Laid-Open No. 10-245359 Japanese Patent Laid-Open No. 11-68308

  However, there are cases where sufficient adhesion cannot be achieved between the insulating layer and the wiring layer by the conventional methods as seen in these. For example, there are many cases where the peel strength shown in the 90-degree peel test according to JIS-C-6481 is less than 1 kg / cm. If the adhesion of the wiring layer to the insulating layer is not sufficient, problems such as failure to properly form a fine wiring structure are likely to occur.

  Further, as described above, a technique is known in which the surface of the insulating layer is roughened to a certain extent and the adhesion is improved by a physical anchor effect at the joint surface between the insulating layer and the wiring layer. When the surface is roughened to an average roughness of about 5 μm as in the prior art, the wiring with a smaller contact area tends to deteriorate the adhesion to the insulating layer, and the miniaturization of the wiring may be hindered. Therefore, with respect to the adhesion of the wiring layer to the insulating layer in the multilayer wiring board having a build-up wiring structure, in the above 90-degree peel test while suppressing the roughening of the insulating layer to the extent that does not hinder the miniaturization of the wiring. It is required to achieve a peel strength of 1 kg / cm or more.

  The present invention has been conceived under such circumstances, and an object thereof is to provide a method for manufacturing a multilayer wiring board in which high adhesion is achieved between an insulating layer and a wiring layer. To do.

  A method for manufacturing a multilayer wiring board having a laminated structure comprising an insulating layer and a wiring layer provided by the present invention is a method in which a support film provided with a metal adhesion layer is provided with a metal adhesion layer. And the step of removing the support film while transferring the metal adhesion layer to the insulating layer, and the step of removing the support film, the insulating layer and the metal adhesion layer laminated thereon Forming a via hole, forming a resist pattern on the metal adhesion layer, and providing a plating film in a non-mask region of the resist pattern, thereby forming a wiring layer on the metal adhesion layer and forming a via in the via hole Steps for removing the resist pattern and removing the metal adhesion layer not covered by the wiring layer, and for the laminated metal adhesion layer and wiring layer And a step of subjecting the Neil process, the.

  According to such a structure, the adhesiveness of the wiring layer with respect to an insulating layer can be improved. In this method, the wiring layer is formed on the insulating layer through the insulating layer made of a resin material and the metallic adhesive layer made of a metal material having relatively high adhesion to the wiring layer made of a metal material. Is laminated on the insulating layer by attaching the support film provided with the metal adhesion layer to the insulating layer via the metal adhesion layer. This laminating step can be performed under a condition in which the insulating layer is pressurized by, for example, a vacuum press or vacuum lamination. Therefore, the metal adhesion layer can be formed in a stronger bonding state to the insulating layer than when the metal adhesion layer is formed by a plating technique or the like. As a result, the adhesion of the wiring layer to the insulating layer is also improved through the metal adhesion layer. In addition, even when a surface roughening treatment is performed on the insulating layer, sufficient adhesion can be obtained while suppressing the degree of surface roughening to such an extent that the miniaturization of the wiring is not hindered. As a result, an excellent fine wiring structure can be formed on the multilayer wiring board.

  Further, in this method, since the metal adhesion layer is not formed in the via hole, even when a material having low conductivity is used for the metal adhesion layer, the electrical connection between the wiring layers can be appropriately achieved.

  In addition, in this method, an annealing process is performed in which the metal adhesion layer and the wiring layer formed thereon are heated to a predetermined temperature. Such an annealing process is performed by the adhesion between the metal adhesion layer and the wiring layer. Done to increase power.

  Preferably, in the step of laminating the support film, the support film is pressed against the insulating layer. Preferably, the step of laminating the support film is performed under heating. With such a configuration, the step of attaching the support film to the insulating layer can be performed more favorably.

  Preferably, the insulating layer includes a thermosetting resin, and the insulating layer in the step of laminating the support film is in a state before complete curing, and further includes the step of curing the insulating layer after laminating the support film. With such a configuration, when the insulating layer contains a thermosetting resin, the insulating layer can be cured at the same time as attaching the metal adhesion layer to the insulating layer, and the manufacturing efficiency of the multilayer wiring board can be improved. Is planned.

  Preferably, before the step of forming the resist pattern, the method further includes a step of forming an electroless plating film on the metal adhesion layer with a metal selected from the group consisting of copper, nickel, and cobalt. According to such a structure, the process of providing the plating film performed later can be performed by the electroplating technique on the electroless plating.

  In the present invention, the metal adhesion layer preferably contains a metal selected from the group consisting of chromium, titanium, nickel, cobalt, and zinc. These metals can improve the adhesion of the conductor material constituting the wiring layer to the resin material constituting the insulating layer. Preferably, the metal adhesion layer is provided at a coverage of 10 to 100% with respect to the insulating layer. Preferably, the metal adhesion layer has a thickness of 0.01 to 1.0 μm. As a result, the formation of the thin structure of the wiring structure or the multilayer wiring board is ensured.

  Preferably, the insulating layer includes a resin selected from the group consisting of polyimide resin, epoxy resin, maleimide resin, bismaleimide resin, cyanate resin, polyphenylene ether resin, polyphenylene oxide resin, olefin resin, and fluorine-containing resin.

  In this invention, Preferably, the average surface roughness of a support film shall be 5 micrometers or less. In the conventional multilayer wiring board, from the viewpoint of improving the adhesion between the insulating layer and the wiring layer, the average surface roughness of the insulating layer in contact with the wiring layer is relatively high, and is about 5 μm by aggressive surface roughening treatment. It had been. The anchor effect based on such high surface roughness, that is, surface unevenness, ensures the adhesion of the wiring layer to the insulating layer. On the other hand, in the present invention, even when the average surface roughness is 5 μm or less and a sufficient anchor effect cannot be expected, by the interposition of the metal adhesion layer formed on the insulating layer by bonding of the support film, The adhesion of the wiring layer to the insulating layer can be improved.

  FIG. 1 is a partial cross-sectional view of a multilayer wiring board 1 according to the present invention. The multilayer wiring substrate 1 includes a core substrate 10, insulating resin layers 20 and 30 stacked on the core substrate 10, a wiring layer 40 embedded between the insulating resin layer 20 and the insulating resin layer 30, and a wiring layer 40. A metal adhesion layer 50 interposed between the insulating resin layer 20 and the insulating resin layer 20;

  The core substrate 10 is formed by laminating a plurality of prepregs in which a glass cloth is impregnated with a resin and the resin is in a B-stage state, and an inner layer wiring pattern 11 is formed of copper on the surface. The wiring layer 40 is formed by patterning on the insulating resin layer 20 and includes an electroless copper plating layer 41 and an electrolytic copper plating layer 42. The metal adhesion layer 50 contributes to improving the adhesion of the wiring layer 40 to the insulating resin layer 20 by being interposed between the insulating resin layer 20 and the wiring layer 40 with a thickness of 0.01 to 1.0 μm. . As a material for constituting the metal adhesion layer 50, for example, chromium, titanium, nickel, cobalt, and zinc can be used. In addition, the wiring layer 40 and the inner layer wiring pattern 11 are electrically connected via the via 40a formed in the via hole 20a. The metal adhesion layer 50 is not formed in the via hole 20a.

  2 to 4 show steps for manufacturing the multilayer wiring board 1 shown in FIG. In the production of the multilayer wiring board 1, first, as shown in FIG. 2A, the metal adhesion layer 50 is formed on the surface of the support film 60. Specifically, a support film 60 having an average surface unevenness of 5 μm or less is prepared, and chromium, titanium or the like is formed on the surface by a wet process such as chromate treatment or plating treatment, or a dry process such as sputtering or vacuum deposition. The metal adhesion layer 50 is formed with a thickness of 0.01 to 1.0 μm using nickel, cobalt, zinc, and the like as constituent materials. As the support film 60, a metal film such as a copper foil and an aluminum foil, or a film made of an alkali-soluble resin may be used. Here, examples of the alkali-soluble resin include an acrylic resin often used for a dry film resist and the like, preferably an acrylic resin having a hydroxyl group.

  Next, as shown in FIG. 2B and FIG. 2C, an uncured insulating resin that becomes the insulating resin layer 20 of the multilayer wiring substrate 1 is formed on the core substrate 10 on which the inner layer wiring pattern 11 has already been formed. The film 20 is laminated, and the support film 60 on which the metal adhesion layer 50 is formed is stacked and bonded so that the metal adhesion layer 50 is in contact with the insulating resin film 20. At this time, depending on the property of the resin material constituting the insulating resin film 20, the bonding step may be performed under heating, or the support film 60 may be pressed against the insulating resin film 20. Moreover, when performing a bonding process under a heating, the insulating resin film 20 may be solidified thru | or hardened by the said heating, and the insulating resin layer 20 may be formed together. When it is not necessary to heat the support film 60, a heating process for solidifying or curing the insulating resin film 20 is performed to form the insulating resin layer 20. As a resin material for forming the insulating resin layer 20, for example, a polyimide resin, an epoxy resin, a maleimide resin, a bismaleimide resin, a cyanate resin, a polyphenylene ether resin, a polyphenylene oxide resin, an olefin resin, a fluorine-containing resin, or the like is used. be able to.

  Next, as shown in FIG. 2D, only the support film 60 is removed by etching or the like while leaving the metal adhesion layer 50. As a result, the metal adhesion layer 50 is uniformly transferred to the insulating resin layer 20. The coverage of the metal adhesion layer 50 with respect to the insulating resin layer 20 is 10 to 100%.

  Next, as shown in FIG. 3A, a via hole 20 a is formed at a predetermined location of the insulating resin layer 20. As a means for forming the via hole 20a, a carbon dioxide laser, excimer laser, or UV-YAG laser can be employed.

  Next, as shown in FIG. 3B, an electroless copper plating process is performed from above the metal adhesion layer 50 to form an electroless copper plating layer 41 having a thickness of 0.3 μm. Even when the metal adhesion layer 50 does not cover the entire surface of the insulating resin layer 20, the electroless copper plating layer 41 formed by the electroless copper plating process covers the entire surface of the insulating resin layer 20. It will function as a current-carrying layer in the electroplating process in a later step. However, when the metal adhesion layer 50 is laminated over the entire surface, the metal adhesion layer 50 can function as an energization layer.

  Next, as shown in FIG. 3C, a resist pattern 70 is formed on the electroless copper plating layer 41. Specifically, a photoresist is laminated on the electroless copper plating layer 41, and the photoresist is patterned by exposure and a phenomenon corresponding to a desired wiring pattern. As the photoresist, for example, NIT-240 (manufactured by Nichigo Morton) or RY-3040 (manufactured by Hitachi Chemical) can be used.

  Next, as shown in FIG. 3D, an electrolytic copper plating process is performed using the electroless copper plating layer 41 as a conductive layer. Thereby, an electrolytic copper plating layer 42 having a thickness of 10 μm is deposited and grown on the non-mask region of the resist pattern 70.

  Next, as shown in FIG. 4A, the resist pattern 70 is peeled off. As the stripping solution, an aqueous sodium hydroxide solution or an organic amine aqueous solution can be used. Next, as shown in FIG. 4B, the electroless copper plating layer 41 not covered by the electrolytic copper plating layer 42 and the metal adhesion layer 50 therebelow are removed. Specifically, the electroless copper plating layer 41 is removed by etching using, for example, a mixed aqueous solution of hydrogen peroxide and sulfuric acid, a cupric chloride aqueous solution, or the like. Etching away using an aqueous cerium ammonium solution. As a result, the wiring layer 40 composed of the electroless copper plating layer 41 and the electrolytic copper plating layer 42 is formed on the insulating resin layer 20 via the metal adhesion layer 50. For example, thereafter, the metal adhesion layer 50 and the wiring layer 40 on the metal adhesion layer 50 are heated to a predetermined temperature and annealed. This annealing process is performed to increase the adhesion between the metal adhesion layer 50 and the wiring layer 40.

  Next, as illustrated in FIG. 4C, the insulating resin layer 30 is stacked on the insulating resin layer 20 from above the wiring layer 40. As a result, the multilayer wiring board 1 shown in FIG. 1 is formed.

  FIG. 4D shows a multilayer wiring board when a series of steps from the transfer of the metal adhesion layer 50 to the insulating resin layer 20 to the formation of the wiring layer 40 are repeated. In this way, a desired number of layers can be achieved by repeating the series of steps a predetermined number of times.

Example 1
<Production of sample substrate>
A chromium adhesion layer as a metal adhesion layer was formed by performing chromate treatment on the surface of a copper foil (thickness: 18 μm, average surface roughness: 1 μm) as a support film. Next, on the copper surface of a copper-clad BT resin substrate (100 × 100 × 1.6 mm, manufactured by Mitsubishi Gas Chemical) as a core substrate, a thermoplastic polyimide film (film thickness: 35 μm, product name: Espanex as an insulating resin layer) , Manufactured by Nippon Steel Chemical Co., Ltd.), and the above-mentioned copper foil on which the chromium adhesion layer was formed was laminated so that the chromium adhesion layer and the polyimide were in contact with each other, and was vacuum-pressed under the conditions of a press temperature of 210 ° C. and a press pressure of 3 MPa. Pressed for a minute. Then, it took out from the vacuum press and heated at 180 degreeC under atmospheric pressure for 1 hour, and the insulating resin layer was hardened. Next, the copper foil as the support film was removed by etching with a mixed solution of hydrogen peroxide and sulfuric acid, leaving only the chromium adhesion layer on the surface of the insulating resin layer. Next, an electroless copper plating film (film thickness: 0.3 μm) is formed on the entire surface of the chromium adhesion layer, and an electrolytic copper plating film (film thickness 30 μm) is formed thereon, thereby forming copper as a wiring layer. A plating film was formed. Next, after annealing at 170 ° C. for 1 hour, the copper plating film was cut into a width of 1 cm. In this way, a sample substrate of this example was produced.

<Measurement of peel strength>
The peel strength of the copper plating film on the sample substrate obtained as described above was measured. As a result, the copper plating film in this example showed a peel strength of 1.2 kgf / cm with respect to thermoplastic polyimide. When the surface roughness of the peeled surface of the copper plating film peeled off due to excessive load was examined, the average surface roughness was 1 μm.

(Example 2)
A sample substrate was prepared in the same manner as in Example 1 except that a copper foil with an average surface roughness of 5 μm was used as the support film instead of a copper foil with an average surface roughness of 1 μm. And about the copper plating film in this sample board | substrate, it carried out similarly to Example 1, and measured peeling strength. As a result, the copper plating film in this example showed a peel strength of 1.2 kgf / cm and was equivalent to that in Example 1.

(Comparative Example 1)
Except for forming a chromium adhesion layer as a metal adhesion layer, only a thermoplastic polyimide film was cured by vacuum press, and electroless copper plating and electrolytic copper plating were applied thereon, in the same manner as in Example 1. An attempt was made to make a sample substrate. Then, the copper plating film was peeled off from the polyimide surface during the electrolytic copper plating. Therefore, the peel strength was not measured.

(Example 3)
<Production of sample substrate>
Titanium having a thickness of 0.2 μm was formed by sputtering on the surface of an aluminum foil (thickness: 25 μm, average surface roughness: 2 μm) as a support film to form a titanium adhesion layer as a metal adhesion layer. A semi-cured thermosetting epoxy resin sheet (film thickness: 50 μm, product as an insulating resin layer) on a copper surface of a copper-clad BT resin substrate (100 × 100 × 1.6 mm, manufactured by Mitsubishi Gas Chemical) as a core substrate Name: SH-9, manufactured by Ajinomoto Co., Inc., and the above-mentioned aluminum foil on which the titanium adhesion layer is formed is laminated so that the titanium adhesion layer and the epoxy resin sheet are in contact with each other, and vacuum lamination is performed at a temperature of 130 ° C. and a pressure of 1 MPa. Lamination was performed for 3 minutes under the conditions. Then, it took out from the vacuum laminate and heated at 170 ° C. for 1 hour under atmospheric pressure to cure the insulating resin layer. Next, the aluminum foil was removed by etching with hydrochloric acid, leaving only the titanium adhesion layer on the surface of the insulating resin layer. Next, an electroless copper plating film (film thickness: 0.3 μm) is formed on the entire surface of the titanium adhesion layer, and an electrolytic copper plating film (film thickness 30 μm) is formed thereon, thereby forming a wiring layer. A copper plating film was formed. Next, after annealing at 170 ° C. for 1 hour, the copper plating film was cut into a width of 1 cm. In this way, a sample substrate was produced.

<Measurement of peel strength>
The peel strength of the copper plating film on the sample substrate obtained as described above was measured. As a result, the copper plating film in this example showed a peel strength of 1.0 kgf / cm with respect to the thermosetting epoxy resin. When the surface roughness of the peeled surface of the copper plating film peeled off due to excessive load was examined, the average surface roughness was 2 μm.

Example 4
A chromium adhesion layer as a metal adhesion layer was formed by performing chromate treatment on the surface of a copper foil (thickness: 18 μm, average surface roughness: 1 μm) as a support film. On the copper surface of a copper-clad BT resin substrate (100 × 100 × 1.6 mm, manufactured by Mitsubishi Gas Chemical) as a core substrate, a thermoplastic polyimide film (film thickness: 25 μm, product name: PIXIO, Kaneka) as an insulating resin layer The above copper foil on which a chromium adhesion layer is formed is further laminated so that the chromium adhesion layer and the polyimide are in contact with each other, and vacuum lamination is performed for 3 minutes at a temperature of 180 ° C. and a pressure of 0.5 MPa. Laminated. Then, it took out from the vacuum laminate and heated at 210 ° C. for 30 minutes under atmospheric pressure to cure the insulating resin layer. Next, the copper foil was etched away with an aqueous cupric chloride solution, leaving only the chromium adhesion layer on the surface of the insulating resin layer. Next, a via hole of φ80 μm was formed on the insulating resin layer with a carbon dioxide laser. Next, electroless copper plating was performed on the chromium adhesion layer to form a conductive layer. Next, a photoresist (trade name: NIT-250, manufactured by Nichigo Morton) was formed on the conductive layer and patterned to form a resist pattern. An electrolytic copper plating layer having a thickness of 30 μm was deposited and grown on the non-mask region of the resist pattern, and then the resist pattern was peeled off. Next, the current-carrying layer that is not covered with the copper electroplating layer is removed by etching with a mixed solution of hydrogen peroxide and sulfuric acid, and then the exposed chromium adhesion layer is removed by etching with an aqueous solution of ceric ammonium nitrate. Thus, the wiring layer was formed on the insulating resin layer through the chromium adhesion layer. As a result, a fine wiring structure having high adhesion to the insulating resin layer and having a wiring width of 30 μm could be formed.

It is sectional drawing of a multilayer wiring board. 1 represents a part of the steps in the method for manufacturing the multilayer wiring board shown in FIG. The process following FIG. 2 is represented. The process following FIG. 3 is represented.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Multilayer wiring board 11 Internal wiring pattern 10 Core board | substrate 20, 30 Insulating resin layer 40 Wiring layer 50 Metal adhesion layer

Claims (11)

A method for producing a multilayer wiring board having a laminated structure comprising an insulating layer and a wiring layer,
Bonding the support film provided with the metal adhesion layer to the insulating layer via the metal adhesion layer;
Removing the support film while transferring the metal adhesion layer to the insulating layer;
After the step of removing the support film, a step of forming a via hole for the insulating layer and the metal adhesion layer laminated thereon,
Forming a resist pattern on the metal adhesion layer and forming a wiring layer on the metal adhesion layer and forming a via in the via hole by providing a plating film in a non-mask region of the resist pattern;
Removing the resist pattern and removing the metal adhesion layer not covered with the wiring layer;
And a step of annealing the laminated metal adhesion layer and wiring layer.   In the step of forming a via hole, a via hole is formed by partially removing the metal adhesion layer and the insulating layer by laser irradiation, and a mask for partially blocking the laser is not used. Item 8. A method for manufacturing a multilayer wiring board according to Item 1.   In the step of forming a via hole, a via hole is formed by partially removing the metal adhesion layer and the insulating layer by laser irradiation, and the laser includes a carbon dioxide laser, an excimer laser, and a UV-YAG laser. The manufacturing method of the multilayer wiring board of Claim 1 or 2 selected from the group which consists of.   4. The method for manufacturing a multilayer wiring board according to claim 1, wherein in the step of attaching the support film, the support film is pressurized against the insulating layer. 5.   The method for producing a multilayer wiring board according to claim 1, wherein the step of laminating the support film is performed under heating.   The insulating layer includes a thermosetting resin, and the insulating layer in the step of laminating the support film is in a state before complete curing, and further includes the step of curing the insulating layer after laminating the support film. The manufacturing method of the multilayer wiring board as described in any one of 1 to 5.   The method further includes a step of forming an electroless plating film on the metal adhesion layer with a metal selected from the group consisting of copper, nickel and cobalt on the metal adhesion layer before the step of forming the resist pattern. 6. The method for producing a multilayer wiring board according to any one of 6 above. The method for manufacturing a multilayer wiring board according to claim 1, wherein the metal adhesion layer includes a metal selected from the group consisting of chromium, titanium, nickel, cobalt, and zinc.   The method for manufacturing a multilayer wiring board according to claim 1, wherein the metal adhesion layer is provided at a coverage of 10% or more with respect to the insulating layer.   The method for producing a multilayer wiring board according to claim 1, wherein the metal adhesion layer has a thickness of 0.01 to 1.0 μm.   The insulating layer includes a resin selected from the group consisting of polyimide resin, epoxy resin, maleimide resin, bismaleimide resin, cyanate resin, polyphenylene ether resin, polyphenylene oxide resin, olefin resin, and fluorine-containing resin. A method for manufacturing a multilayer wiring board according to any one of 1 to 10.

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