JP2007103440A - Wiring board and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wiring board wherein a conductor pattern with a very fine pitch can be formed and the conductive pattern transferred to an insulating substrate is high in peeling intensity, and to provide a method of manufacturing the same. <P>SOLUTION: First, an ultra-thin conductive metal layer 12 is formed on the surface of a supporting substrate 10, and a resist pattern is formed on the surface of the ultra-thin conductive metal layer. A plating layer having the nearly same thickness as the resist pattern is formed on the surface of the ultra-thin conductive metal layer not covered with the resist pattern, by electric plating, and then a nodule 20 is formed on the surface of the formed plating layer by electric plating. Next, the adhesive layer of a substrate film having an adhesive layer 22 is brought into contact with the surface of an insulating film, thus allowing the nodule to invade the adhesive layer. Then, the supporting substrate is peeled off, and a resist pattern formed on the supporting substrate and the plating layer are transferred to the side of a substrate film, the resist pattern transferred to the side of the substrate film is removed, and a conductor pattern 18 made of copper is formed on the surface of the substrate film. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method of manufacturing a wiring board by a transfer method and a wiring board formed by the manufacturing method.

  In general, a wiring board forms a photosensitive resin coating on the surface of a metal layer laminated on the surface of a base material, and exposes and develops the photosensitive resin coating to obtain a desired photosensitive resin cured body. The masking material left in the shape is formed, and then the portion of the metal layer not provided with the masking material is etched (subtractive method). In such a conventional method, it is common to form a wiring pattern having a so-called cross-sectional trapezoidal cross-sectional shape in which the upper cross-sectional length of the formed wiring pattern is short and the insulating film side (lower) cross-sectional length is long. Yes (undercut phenomenon). Further, the conventional method as described above has a limit on the width of the wiring pattern to be formed, and is approaching the limit as a method of forming a wiring pattern thinner than the recent fine pitch wiring pattern.

As a completely different method based on the subtractive method as described above, there is known a transfer method in which a conductor pattern formed separately from an insulating film is bonded onto the insulating film.
However, in this transfer method, for example, as shown in Patent Document 1 (Japanese Patent Laid-Open No. 2000-71387) or Patent Document 2 (Japanese Patent Laid-Open No. 9-64514), a conductor pattern is buried in a base material such as an insulating substrate. However, for example, a wiring board manufactured by the transfer method as described above has a problem that a method established by a conventional wiring board cannot be adopted, such as an anisotropic conductive adhesion.

Further, as shown in Patent Document 3 (Japanese Patent Laid-Open No. 11-251722) or Patent Document 4 (Japanese Patent Laid-Open No. 4-260389), even if a conductor pattern can be formed in a convex shape on the surface of an insulating substrate, In such a method described in Patent Document 3 or Patent Document 4, the peel strength of the conductor pattern with respect to the insulating substrate is not sufficiently high. Further, Patent Document 5 (Japanese Patent Laid-Open No. 11-266069) and Patent Document 6 (Japanese Patent Laid-Open No. 11-266070) disclose inventions of a transfer method focusing on peel strength. However, it is very difficult to form a fine pitch conductor pattern by the conventional method.
JP 2000-71387 A Japanese Patent Laid-Open No. 9-64514 Japanese Patent Laid-Open No. 11-251722 JP-A-4-260389 Japanese Patent Laid-Open No. 11-266069 Japanese Patent Laid-Open No. 11-266070

An object of the present invention is to provide a wiring board by a novel transfer method and a manufacturing method thereof.
More specifically, an object of the present invention is to provide a wiring board capable of forming a very fine-pitch conductor pattern and having a high peel strength of the transferred conductor pattern with respect to an insulating substrate, and a method for manufacturing the same.

In addition, the present invention is a wiring board that can form a very fine-pitch conductor pattern and has a high peel strength of the transferred conductor pattern with respect to the insulating substrate, and the conductor pattern has a convex shape on the surface of the insulating substrate. An object of the present invention is to provide a wiring board that can be incorporated into an electronic device by anisotropic conductive bonding and a method for manufacturing the same, as in the case of a conventional wiring board.

  In the method for producing a wiring board of the present invention, an ultrathin conductive metal layer is formed on the surface of a support base material, a resist pattern is formed on the surface of the ultrathin conductive metal layer, and the resist pattern is covered. After forming a plating layer having the same thickness as the resist pattern on the surface of the non-thin conductive metal layer by electroplating, nodules are formed on the surface of the formed plating layer by electroplating; An adhesive layer of a base film having an adhesive layer is brought into contact with the surface of the insulating film, and the nodule is intruded into the adhesive layer, and then the support base is peeled off to be formed on the support base. Transfer the resist pattern and plating layer to the base film side, and then remove the resist pattern transferred to the base film side to form a copper conductor pattern on the surface of the base film. It is a symptom.

  As described above, in the method for manufacturing a wiring board according to the present invention, a nodule is formed on the surface of the conductor pattern, and the nodule penetrates into the adhesive layer of the base film, thereby increasing the contact surface with the adhesive. At the same time, due to the nodule throwing effect, the conductor pattern has a high peel strength with respect to the base film.

  According to the present invention, a very fine pitch conductor pattern can be formed by a transfer method. And although this conductor pattern is formed by the transfer method, it has high peel strength with respect to a base film.

  Furthermore, in the method of the present invention, a conductive resin is plated on a recess formed by exposing and developing a photosensitive resin into a desired shape to form a conductor pattern, and after forming nodules on the surface of the conductor pattern, a base film Since the conductor pattern is transferred to the wiring board, the side surface of the cross section of the conductor pattern is formed substantially at right angles to the surface of the insulating film. Therefore, the cross sectional shape of the conductor pattern of the wiring board manufactured by the method of the present invention is rectangular. It is formed. Thus, since the cross-sectional shape of the conductor pattern is rectangular and the undercut phenomenon or the like does not appear in the wiring pattern manufactured by the conventional method, a very fine conductor pattern can be formed densely.

Next, the manufacturing method of the wiring board of the present invention and the wiring board obtained in this way will be specifically described.
FIG. 1 is a cross-sectional view showing an example of a cross section of a substrate in each step in the method for manufacturing a wiring board of the present invention.

As shown in FIGS. 1A and 1B, in the method for manufacturing a wiring board according to the present invention, an ultrathin conductive metal layer 12 is formed on the surface of a support base 10.
Here, as the support substrate 10, a film, a sheet, a plate, or the like that is usually formed from an insulating resin such as a synthetic resin film or a synthetic resin plate can be used. The thickness and shape of the support base 10 are not particularly limited, but when a wiring board is continuously manufactured in the present invention, a synthetic resin film having self-form supportability and flexibility or A sheet is preferable, and when a synthetic resin sheet or a synthetic resin film is used as such a supporting substrate 10, the thickness of the supporting substrate 10 is usually within a range of 15 to 50 μm, preferably 35 to 70 μm. is there. Further, since the ultrathin conductive metal layer 12 is formed on the surface of the support base material 10 by sputtering or the like, it is preferable that the support base material 10 has a certain degree of heat resistance. Examples of these include polyimide, polyimide amide, polyamide; polyesters such as PET and PEN. In particular, in the present invention, it is preferable to use a film or sheet formed from PET or polyimide.

An ultrathin conductive metal layer 12 is formed on the surface of the support substrate 10 as described above. In the present invention, the ultrathin conductive metal layer 12 serves as an electrode for depositing a conductive metal when the conductive pattern 16 is formed by electroplating, and is formed from a conductive metal such as copper, nickel, or chromium. . Such an ultrathin conductive metal layer 12 can be formed by depositing the conductive metal as described above on the surface of the support substrate 10 using a deposition method such as sputtering, vapor deposition, or plating. it can. The ultrathin conductive metal layer 12 is not particularly limited as long as it can supply sufficient power for plating a conductor metal in a later step, but is usually 5 × 10 ^−3. It is about 5 μm, preferably about 5 × 10 ^{−3 to 3} μm. Particularly in the present invention, it is preferable to form the ultrathin conductive metal layer 12 by sputtering. In forming the ultrathin conductive metal layer 12 by sputtering in this way, copper or nickel is used as the conductive metal. Thus, a conductive metal layer having a thickness of 5 × 10 ⁻³ to 5 μm, preferably 5 × 10 ^{−3 to} 0.1 μm is desirable.

  After forming the ultrathin conductive metal layer 12 in this way, a photosensitive resin layer is formed on the surface of the ultrathin conductive metal layer 12, and the photosensitive resin layer is exposed and developed to form a recess. Form 16. The photosensitive resin includes a type of photosensitive resin that cures upon exposure and a type of photosensitive resin that becomes soluble upon exposure. In the present invention, which type of photosensitive resin is used. Can do. The coating thickness of the photosensitive resin is desirably substantially the same as the thickness of the conductor pattern to be formed, and the thickness of the photosensitive resin layer thus formed is usually 5 to 30 μm, preferably It exists in the range of 8-20 micrometers. FIG. 1C shows a cross section of the photosensitive resin layer as described above exposed and developed. In FIG. 1 (c), the photosensitive resin layer is exposed and developed to form a recess 16 surrounded by a cured body 14 of the photosensitive resin. The conductive metal layer 12 is exposed.

  After the photosensitive resin is exposed and developed in this manner to form the recess 16, a metal is deposited in the recess 16 to form a conductor pattern. FIG. 1 (d) shows a cross-section in a state in which a conductive metal is deposited by electroplating in the recess 16 formed by exposing and developing the photosensitive resin layer as described above to form a conductor pattern 18. Has been. Here, the conductive pattern 18 can be formed of various conductive metals such as copper, nickel, aluminum, silver, and gold. However, in the present invention, the conductive pattern 18 is preferably formed of copper or a copper alloy. The thickness of the conductor pattern 18 at this time can be made substantially the same as the thickness of the cured body 16 of the photosensitive resin, but the conductor pattern 18 is formed by forming the nodules 20 on the surface of the conductor pattern 18 in the next step. Therefore, it is desirable to form it slightly thinner than the cured body 16 of the photosensitive resin.

Such a conductor pattern 18 is formed by electroplating. That is, using the ultrathin conductive metal layer 12 as one electrode, a conductive metal is deposited on the surface of the ultrathin conductive metal layer 12 by electroplating. The electroplating conditions at this time are, for example, when the conductor pattern 18 is made of copper, the plating current density is 0.5 to 8 A / dm ² , the copper ion concentration in the plating solution is 10 to 100 g / liter, and the plating temperature is 20 to 60 ° C. The plating time is preferably 6 to 80 minutes. By performing electroplating under such conditions, a dense copper plating layer can be formed. The plating solution used for forming the conductor pattern used here is a plating solution that is generally used. In the present invention, the metal forming the conductor pattern 18 and the metal forming the ultrathin conductive metal layer 12 may be the same or different.

After the conductor pattern 18 is formed as described above, a nodule 20 is formed on the surface of the conductor pattern 18 as shown in FIG. The nodules 20 are typically dendritic metal plating having a height of 0.1 to 15 μm, and can be formed by electroplating in the same manner as the conductor pattern 18 described above. This nodule 20 is for firmly fixing the conductor pattern 18 and does not particularly need to be the same as the metal forming the conductor pattern 18, but the nodule 20 and the conductor pattern 18 are integrated. In order to form the target, it is preferable to form the same metal. For example, when the conductor pattern is formed of copper or a copper alloy, the nodule 20 is preferably formed of copper or a copper alloy.

When this nodule 20 is formed of copper or a copper alloy, the plating conditions are: a plating current density of 3 to 30 A / dm ² , a copper ion concentration in the plating solution of 1 to 50 g / liter, and a plating temperature of 20 to
It is desirable that the temperature is 60 ° C. and the plating time is 5 to 600 hours, preferably 5 to 480 seconds.

As the copper plating bath used when the nodule 20 is formed of copper or a copper alloy, a copper sulfate plating bath, a copper pyrophosphate plating bath, or the like is suitable.
By performing electroplating as described above, copper precipitates in a dendritic form to form nodules 20. The height of the nodule 20 is for fixing the conductor pattern 18 in the adhesive layer 22 and is usually in the range of 0.1 to 15 μm, preferably 1 to 10 μm. The nodule 20 formed in this way penetrates into the adhesive layer of the base film to be stuck in the next step and firmly fixes the conductor pattern to the adhesive layer.

  After forming the nodule 20 in this manner, if necessary, the plated nodule may be subjected to bump plating and cover plating. The bump plating is a plating method in which fine granular metal is deposited on the formed nodules 20, and the cover plating is a plating method in which the fine granular metal thus deposited by the bump plating is covered and fixed.

  After forming the nodule 20 as described above, the base film 30 having the insulating film 24 and the adhesive layer 22 is pasted, and the nodule 20 formed as described above enters the adhesive layer 22 Let

FIG. 1 (f) shows a cross-section in a state where an insulating film 24 and a base film 30 having an adhesive layer 22 formed on the surface of the insulating film 24 are attached to the surface on which the nodules 20 are formed. Has been. The base film 30 to be attached here has an insulating film 24 and an adhesive layer 22, and examples of the resin material forming the insulating film 24 include polyimide, polyimide amide, polyester, polyphenylene sulfide, Examples include ether imide, fluororesin, liquid crystal polymer, epoxy resin, and glass-epoxy resin composite. The thickness of the insulating film 24 is not particularly limited, and may be a plate shape or a flexible film shape.

When the base film 30 is plate-shaped, a plate-shaped substrate can be formed using, for example, an epoxy resin, a glass-epoxy resin composite, or the like.
Moreover, when the base film 30 is a film having flexibility, it can be used by forming a film from the resin as described above. The thickness of the film at this time varies depending on the resin used, but is usually 70 μm or less, preferably 5 to 70 μm.
In particular, in the present invention, it is preferable to use a polyimide film, and the polyimide film used at this time usually has a thickness in the range of 5 to 70 μm, preferably 3 to 70 μm, particularly preferably 30 to 45 μm. Yes.

The insulating film 24 may be a single layer or a laminated body in which a plurality of layers are laminated. In addition, when the insulating film 24 is a laminated body in which a plurality of layers are laminated, the plurality of layers are laminated with an adhesive component, and if necessary, the outermost layer laminated (on the side where no conductor pattern is formed) The outermost layer) can be peeled off and used. In this case, in order to facilitate peeling, an insulating film layer / release layer / adhesive / reinforcing film is used by interposing a layer made of a release agent on the surface of the insulating film laminated with an adhesive. An insulating film 24 having a plurality of layer configurations can be used.

  When the reinforcing film is peeled in this way, the adhesive is peeled off together with the reinforcing film, but in many cases, the release layer made of a silicon compound or a silicon resin is transferred to the back surface of the insulating film body, and the insulating film It often remains on the main body. By leaving the release layer in this way, it is possible to prevent the base film forming component from being fused to the surface of the bonding tool.

  The adhesive layer 22 forming the base film 30 used in the present invention is to infiltrate the nodules 20 formed in the previous step and fix the conductor pattern 18, and for this purpose, it is formed on the base film 30. The thickness of the adhesive layer 22 is determined with reference to the height of the nodule 20. As described above, the height of the nodule 20 is usually in the range of 0.1 to 15 μm, preferably 1 to 10 μm. Therefore, the thickness of the adhesive layer 22 is equal to or higher than the height of the nodule. Desirably, the thickness is usually 1 to 24 μm, preferably 2 to 15 μm.

  In the present invention, it is preferable to use a thermosetting adhesive for the adhesive layer constituting the base film 30. Examples of such thermosetting adhesives include epoxy resin adhesives, polyimide adhesives, acrylic adhesives, urethane adhesives, and the like. In particular, in the present invention, it is preferable to use an epoxy adhesive and / or a polyimide adhesive. That is, the epoxy adhesive and the polyimide adhesive soften to the extent that the nodules 20 penetrate by heating in the state of the precursor before curing, but after the nodules 20 penetrate, further heating By doing so, these adhesives harden and form a hardened body of the adhesive. Such a cured product of the adhesive exhibits good acid resistance and does not soften even when heated in a later step, and firmly holds the conductor pattern 18 by the anchor effect of the nodule 20.

  In order to attach the base film 30 as described above to the support base on which the nodules 20 are formed, the adhesive layer 22 of the base film 30 and the surface on which the nodules 20 are formed face each other. The material film 30 is disposed and usually laminated by pressing under heating. By heating in this way, the adhesive layer 22 is softened, and the nodules 20 are liable to enter the adhesive layer 22, and further pressurization causes the nodules to enter the softened adhesive layer 22. Furthermore, by heating, at least a part of the adhesive forming the adhesive layer 22 is cured while the nodule 20 has entered.

The temperature required for softening the adhesive layer 22 is normally 100 to 200 ° C., and the pressure required to allow the nodule 20 to enter the adhesive layer 22 is 0.5 to 4. It is in the range of 0 kg / cm ² . In addition, in order to harden the adhesive bond layer 22 more reliably, after adhering the base film as described above, it can be stored in a heating chamber adjusted to a temperature within the range of 100 to 300 ° C.

As shown in FIG. 1 (f), the laminated body laminated as described above is a supporting substrate 10 / ultra thin conductive metal layer 12 / cured photosensitive resin body 14 / conductor pattern 18 (with nodules 20) / It has a layer structure of adhesive layer 22 / base film 24.

In the method for manufacturing a wiring board according to the present invention, the support substrate 10 is peeled from the laminate formed as described above. FIG. 1 (g) shows a cross-sectional view of the support substrate 10 peeled off, and the ultrathin conductive metal layer 12 is exposed on one side when the support substrate 10 is peeled off.

In the present invention, in order to remove the ultrathin conductive metal layer 12, the laminate shown in FIG. 1 (g) is etched to dissolve and remove the ultrathin conductive metal layer 12.
The ultra-thin conductive metal layer 12 is formed of copper, copper alloy, nickel, etc., and the ultra-thin conductive metal layer 12 is very thin, so it can be easily used with a commonly used etching solution. Can be removed. FIG. 1 (h) shows a state where the ultrathin conductive metal layer 12 is removed and the surface of the conductor pattern 18 is exposed. By removing the ultrathin conductive metal layer 12 in this way, the conductor patterns 18 become electrically independent from each other.

  In the present invention, it is preferable that a layer made of a release resin such as a silicon compound is disposed on the surface of the base film 30 where the conductor pattern 18 is not formed. If such a layer is present when an electronic component is mounted, the bonding tool base film forming component can be prevented from being fused.

After the ultrathin conductive metal layer 12 is removed in this way, the photosensitive resin cured body 14 between the conductor patterns 18 is removed to make the conductor patterns 18 independent. The photosensitive resin cured body 14 can be removed by various methods, but a method of elution using a solvent or a method of stripping and removing using an alkaline cleaning solution is advantageous. As the organic solvent used here, an organic solvent that does not attack the insulating film 24 and the adhesive layer 22 constituting the base film 30 can be used. Further, since the cured body 14 of the photosensitive resin is usually easily peeled off using an alkaline cleaning liquid, the method of removing it using the alkaline cleaning liquid is the most realistic and is very advantageous at low cost. FIG. 1 (i) shows a cross section of the wiring board in a state in which the cured body 14 of the photosensitive resin is removed and the conductor pattern is made independent.

In the method of the present invention, the ultrathin conductive metal layer 12 may be peeled off together with the supporting substrate 10 when the supporting substrate 10 is peeled off from the stage of FIG. The ultrathin conductive metal layer 12 is formed on the surface of the support substrate 10 by a method such as sputtering, but the adhesion of the ultrathin conductive metal layer 12 to the support substrate 10 at this time is not increased. The adhesion of the ultrathin conductive metal layer 12 to the support substrate 10 can be improved by changing the sputtering conditions or the like, or by changing the formation conditions of the ultrathin conductive metal layer 12. By firmly bonding the ultrathin conductive metal layer 12 to the surface of the support base material 10 in this way, when the support base material 10 is peeled off, the ultrathin conductive metal layer 12 is also peeled off together with the support base material 10, The state shown in FIG. 2 (h ′) is obtained without going through the state of FIG. 1 (g). As described above, when the ultrathin conductive metal layer 12 is peeled together when the support substrate 10 is peeled off, even if the etching step for removing the ultrathin conductive metal layer 12 is omitted, FIG. The wiring board shown in i ′) can be manufactured.

Further, in FIG. 1 (f), instead of attaching the base film 30 composed of the adhesive layer 22 and the insulating film 24, as shown in FIG. 3 (f ″), the adhesive layer 32 is thickly applied. Then, by curing the adhesive layer 32, an insulating film can be obtained as shown in FIG. In this embodiment, the cured body of the adhesive layer 32 is used as an adhesive layer as well as an insulating film, and a wiring board having a layer configuration much smaller than that of the above-described wiring board can be obtained. As a resin for forming such an adhesive layer 32, for example, a polyimide precursor or the like can be used.

In the wiring board of the present invention formed as described above, the conductor pattern 18 is formed on the base film 30 or the substrate as shown in FIGS. 1 (i), 2 (i ′), and 3 (i ″). From the surface of the cured body of the adhesive layer 32 that acts in the same way as the material film 30, it is formed substantially at right angles, and the formed conductor pattern does not undercut.

Therefore, according to the method of the present invention, since the rectangularity of the formed conductor pattern is high and it is not necessary to consider the narrowing of the space 26 between the conductor patterns due to undercut, it is necessary to secure an extra space between the conductor patterns. There is no. Further, in the present invention, a photosensitive resin is exposed to form a space in which a conductor pattern is to be formed, and a conductive metal is deposited in this space to form a conductor pattern. The exposure accuracy of the photosensitive resin is very high. In addition, since the conductive pattern is formed by depositing metal in the space formed by the cured body of the photosensitive resin, the photosensitive resin can be exposed to the wavelength of light used for exposure. In view of this point and the fact that the photosensitive resin can form a space substantially perpendicular to the support substrate, the line width that could not be manufactured by the conventional method is much less than 1 μm. It is possible to form a very fine conductor pattern.

  Moreover, since the conductor pattern 18 formed in this way is firmly fixed to the adhesive layer by the anchor effect of the nodule 20, the conductor pattern 18 has a very high peel strength.

Furthermore, the wiring board obtained by the method of the present invention has a conductor pattern formed in a convex shape on the surface of the base film, and is incorporated into an electronic device using an anisotropic conductive adhesive like a conventional printed wiring board. It becomes possible.
〔Example〕
Next, the present invention will be described in more detail with reference to examples of the method for manufacturing a wiring board of the present invention and the wiring board manufactured by this method, but the present invention should not be limited thereto.

  A polyimide film having a thickness of 38 μm was used as a supporting substrate, and an ultrathin copper layer having an average thickness of 0.1 μm was formed on one surface of the polyimide film as the supporting substrate by sputtering.

  Next, a photosensitive resin layer (average dry thickness: 13 μm) was formed on the surface of the ultrathin copper layer, and a predetermined pattern was formed by exposing and developing the photosensitive resin layer. The ultrathin copper layer was exposed at the bottom of the portion where the photosensitive resin layer of the pattern thus formed was removed.

Next, the laminate on which the pattern was formed as described above was placed in a commercially available copper sulfate plating bath (copper concentration: 24 g / liter), plating current density 2.0 A / dm ² , plating temperature 30 ° C., plating time 20 minutes. Electro copper plating was performed under the above conditions, and copper was deposited at an average thickness of 8 μm on the portion where the photosensitive resin was not formed to form a conductor pattern. Note that the thickness of the deposited copper was 5 μm thinner than the thickness 13 μm of the photosensitive resin layer.

Next, the obtained laminate is placed in a copper sulfate plating bath (copper concentration: 8 g / liter) and subjected to electro copper plating under conditions of a plating current density of 1 A / dm ² , a plating temperature of 30 ° C. and a plating time of 480 seconds. Nodules having an average height of 3 μm were formed on the surface of the film.

  Next, a base film was attached to the surface where the nodules were formed. The base film has a polyimide film having a thickness of 38 μm and an epoxy adhesive layer having a thickness of 8 μm formed on one surface of the polyimide film. The nodules softened and formed on the surface of the conductor pattern are softened to such an extent that they can enter the epoxy adhesive layer. An extremely thin silicon resin layer is formed on the surface opposite to the surface on which the adhesive layer is formed.

The base film is arranged so that the epoxy adhesive layer and the surface on which the nodules are formed, and pressure-bonded under the conditions of a temperature of 150 ° C. and a linear pressure of 2.0 kgf / cm.
The temperature was maintained at 0 ° C. for 5 hours.

After the adhesive layer was cured as described above, the ultrathin copper layer was exposed on the peeled surface by peeling the support substrate.
This laminate was etched with an ultrathin copper layer using a copper etchant to expose the conductor pattern.

Subsequently, by washing with an alkali washing liquid, the cured body of the photosensitive resin was peeled off to make the conductor pattern independent.
When the peel strength of the conductor pattern formed as described above was measured, the peel strength was 1.4 kgf / cm. Contrary to the fact that the peel strength of the conductor pattern of the wiring board formed in the same manner except that no nodules were formed was 0.33 kgf / cm, the peel strength of the conductor pattern in the wiring board obtained by the present invention was remarkably high. I understand that. Moreover, the peel strength of the wiring pattern in the printed wiring board obtained by arranging copper foil on the polyimide film surface and selectively etching this copper foil is usually 1.0 to 2.5 kgf.
According to the method of the present invention, it is possible to manufacture a wiring board having a conductor pattern having a peel strength equivalent to or higher than this.

  In addition, as described above, the conductor pattern formed by the method of the present invention is formed so as to protrude in a convex shape from the surface of the insulating film. Therefore, when anisotropic conductive bonding is performed using the wiring pattern obtained as described above, good electrical conduction in the pressing direction can be secured, and insulation in the width direction is also good. It was.

In Example 1, the same operation was performed except that the adhesion between the sputtering metal and the supporting substrate was increased by changing the sputtering conditions for the supporting substrate.
After forming the nodule, the substrate film was adhered, and then the support substrate was peeled off. As a result, the ultrathin copper foil layer was peeled off together with the support substrate. Therefore, the ultrathin copper layer was also peeled off by peeling the supporting substrate, and the conductive pattern was exposed on the peeled surface, so that the etching process for removing the ultrathin copper layer was omitted.

Subsequently, by washing with an alkali washing liquid, the cured body of the photosensitive resin was peeled off to make the conductor pattern independent.
When the peel strength of the conductor pattern formed as described above was measured, the peel strength was 1.4 kgf / cm. Contrary to the fact that the peel strength of the conductor pattern of the wiring board formed in the same manner except that no nodules were formed was 0.33 kgf / cm, the peel strength of the conductor pattern in the wiring board obtained by the present invention was remarkably high. I understand that. Moreover, the peel strength of the wiring pattern in the printed wiring board obtained by arranging copper foil on the polyimide film surface and selectively etching this copper foil is usually 1.0 to 2.5 kgf.
According to the method of the present invention, it is possible to manufacture a wiring board having a conductor pattern having a peel strength equivalent to or higher than this.

  In addition, as described above, the conductor pattern formed by the method of the present invention is formed so as to protrude in a convex shape from the surface of the insulating film. Therefore, when anisotropic conductive bonding is performed using the wiring pattern obtained as described above, good electrical conduction in the pressing direction can be secured, and insulation in the width direction is also good. It was.

According to the present invention, a very fine pitch conductor pattern can be formed by a transfer method. And although this conductor pattern is formed by the transfer method, it has high peel strength with respect to a base film.

  In addition, since the conductor pattern is formed in a convex shape from the surface of the base film, it can be incorporated into an electronic device by anisotropic conductive adhesion as in the case of a conventional film carrier tape.

  Furthermore, in the method of the present invention, a conductive resin is plated on a recess formed by exposing and developing a photosensitive resin into a desired shape to form a conductor pattern, and after forming nodules on the surface of the conductor pattern, a base film Since the conductor pattern is transferred to the wiring board, the side surface of the cross section of the conductor pattern is formed substantially at right angles to the surface of the insulating film. Therefore, the cross sectional shape of the conductor pattern of the wiring board manufactured by the method of the present invention is rectangular. It is formed. Thus, since the cross-sectional shape of the conductor pattern is rectangular and the undercut phenomenon or the like does not appear in the wiring pattern manufactured by the conventional method, a very fine conductor pattern can be formed densely.

  In addition, since the wiring board obtained by the method of the present invention has a conductive pattern protruding on the surface of the insulating film, it is anisotropically conductive like the printed wiring board manufactured by the conventional method. It can be incorporated into an electronic device using an adhesive.

FIG. 1 is a cross-sectional view schematically showing a cross section in each step of the method for manufacturing a wiring board of the present invention. FIG. 2 is a cross-sectional view schematically showing a cross section in each step in another aspect of the method for manufacturing a wiring board of the present invention. FIG. 3 is a cross-sectional view schematically showing a cross section in each step in another aspect of the method for manufacturing a wiring board of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Support base material 12 ... Ultra-thin electroconductive metal layer 14 ... Hardened body 16 of photosensitive resin ... Recess 18 ... Conductor pattern 20 ... Nodule 22 ... Adhesive layer 24 ... Insulating film 30 ... Base film 32 ... Adhesive layer

Claims (9)

  An ultrathin conductive metal layer is formed on the surface of the support substrate, a resist pattern is formed on the surface of the ultrathin conductive metal layer, and the surface of the ultrathin conductive metal layer not covered with the resist pattern is formed. After the plating layer having the same thickness as the resist pattern is formed by electroplating, nodules are formed by electroplating on the surface of the formed plating layer, and then an adhesive layer is provided on the surface of the insulating film. The adhesive layer of the base film is brought into contact, the nodule is allowed to enter the adhesive layer, the support base is peeled off, and the resist pattern and the plating layer formed on the support base are used as the base film. A method for producing a wiring board, comprising: transferring a conductive pattern on a surface of a base film by removing the resist pattern transferred to the base film side and then transferring to the base film side. The ultrathin conductive metal layer is a conductive layer having a thickness of 5 × 10 ⁻³ to 5 μm formed on the surface of the support base material by sputtering or precipitation reaction of the conductive metal. A method for manufacturing a wiring board according to item 1. 2. The wiring board according to claim 1, wherein the resist pattern is formed by forming a photosensitive resin layer on a surface of an ultrathin conductive metal layer, and exposing and developing the photosensitive resin layer. Manufacturing method. The nodule is a copper nodule, and electroplating conditions for forming the nodule are as follows: current density 3 to 30 A / dm ² , plating solution temperature 20 to 60 ° C., Cu ion concentration 1 to 50 g / liter in the plating solution, 2. The method for manufacturing a wiring board according to claim 1, wherein the plating time is 5 to 600 seconds.   The base film is a polyimide film having an average thickness of 15 to 150 μm, and an adhesive layer having an average thickness of 1 to 24 μm made of an epoxy-based thermosetting resin is formed on the surface of the base film. The method of manufacturing a wiring board according to claim 1, wherein The resist pattern and the plating layer formed on the support substrate are transferred to the substrate film side, and after removing the support, the ultrathin conductive metal layer remaining on the surface of the transferred resist pattern and the plating layer 2. The method for manufacturing a wiring board according to claim 1, wherein the step is removed by etching.   A nodule integrated with the conductor pattern is formed at the base film side bottom of the wiring pattern, and the nodule penetrates into the cured resin body constituting the base film, and the conductor pattern is fixed to the base film. A wiring board characterized by being made.   8. The wiring board according to claim 7, wherein a side surface in the cross section of the conductor pattern is formed substantially at right angles to the surface of the base film.   8. The substrate film according to claim 7, wherein the base film comprises a polyamide film having an average thickness of 5 to 70 μm and a thermosetting adhesive having an average thickness of 1 to 24 μm laminated on the polyimide film. Wiring board.

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