JP2007158017A - Wiring board and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a wiring board with an ultrafine wiring pattern buried in an insulator. <P>SOLUTION: The wiring board manufacturing method comprises a step of contacting and pressing a precision press mold with a press mold emboss pattern formed on a male mold composed of hard members on the surface of a support, to a metal film on an organic insulating base composed of the metal film laminated on a resin base of an organic insulating base, thereby forming recesses corresponding to the press mold emboss pattern formed on the male mold toward the deep of the organic insulating base from the metal film of the organic insulating base; then removing the precision press mold; forming a thicker metal plating layer than the depth of the recesses formed on the metal film of the organic insulating base; and polishing the metal plating layer until the organic insulating base is exposed from the metal plating layer surface, thereby forming a wiring pattern with the plating metal filled in the recesses on the organic insulating base. Thus, a wiring board is manufactured with a wiring pattern buried in the organic insulating base. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a novel method for manufacturing a wiring board and a wiring board manufactured by this method. More specifically, the present invention relates to a method of manufacturing a wiring board in which a very fine wiring pattern is embedded in an insulating base material, and a wiring board manufactured by this method.

Recently, electronic products have been further miniaturized, and for example, a subtractive method is suitable for forming a fine pitch wiring pattern.
However, even if an ultrafine pitch wiring pattern is manufactured by the subtractive method (Subtractive method), which is considered suitable for forming such a fine pitch wiring pattern, the wiring pattern is not formed on the surface of the insulating substrate. Due to the protruding shape, when soldering, the solder flows through the bottom of the wiring pattern (the bottom of the wiring pattern on the insulating substrate side), causing a short circuit between adjacent wiring patterns. May be.

In particular, it is considered that the risk of a short circuit due to the flowing out of the solder is increased in the recent ultra-fine wiring pattern.
As a method of preventing the formation of a bridge due to such solder connection, there is a method of filling the space between wiring patterns with a solder resist, but this method requires a very high printing alignment accuracy when the wiring pattern becomes an ultra fine pitch. Even if the coating can be performed with high positional accuracy, it is almost impossible to completely match the portion to be coated with the portion actually coated by flowing out the applied solder resist.

  Although it is conceivable to use a photoresist instead of the solder resist as described above, there is still a limit to the alignment accuracy of the photomask, which is insufficient as a method for manufacturing an ultra fine pitch wiring pattern. It is.

In addition to the alignment problem described above, chip patterns (CSP) using solder balls as outer terminals are often used for wiring patterns, but the conventional subtractive method (Subtractive The CSP manufactured by the above method has a problem that the area of the pad including the shoulder portion is likely to be non-uniform, and the height of the molten solder balls is not uniform. Also, in such CSP, when solder balls are placed on the pads of holes formed in an insulating film such as a polyimide film and soldered, cavities are likely to occur at the corners of the pad bottom, and the solder balls are The reliability of the electrical connection used can be a problem.

In JP 2003-218500 A (Patent Document 1), a conductive metal foil laminated on a support is processed into a wiring pattern, and the wiring pattern thus formed is embedded in a thermoplastic resin. Then, a method for producing an embedded conductor pattern film in which a support is peeled off and a wiring pattern is embedded in a thermoplastic resin film is disclosed.

However, in this method, the conductor pattern embedded in the thermoplastic resin is formed by etching a conductive metal such as copper foil using a photolithography method, and has a wiring pattern with an ultrafine pitch. It is not suitable for the production of wiring boards.
JP 2003-218500 A

An object of the present invention is to provide a novel manufacturing method of a wiring board in which an ultrafine wiring pattern is embedded in an insulator.
Another object of the present invention is to provide a novel wiring board formed by the above-described method for manufacturing a wiring board.

  The method for manufacturing a wiring board according to the present invention includes a precision stamping method in which a stamp pattern is formed on the surface of a stamp base on the surface of an organic insulating substrate and a metal thin film formed on the surface of the organic insulating substrate. By pressing the mold in contact with the mold and forming a recess corresponding to the stamp pattern formed on the precision stamp mold from the metal thin film side toward the deep part of the organic insulating substrate, the metal A metal plating layer thicker than the depth of the formed recess is formed on the thin film, and the plating metal is filled in the recess formed by the precision stamping die, and then the organic insulating substrate is formed from the surface of the metal plating layer. The wiring pattern is formed by polishing the metal plating layer until it is exposed.

The wiring board of the present invention is characterized in that a wiring pattern is formed by filling the surface of a recess formed in an organic insulating base material with a plating metal via a metal thin film.
It is preferable to form a metal plating layer different from the metal filled in the recesses on the surface of the wiring pattern.

  In the method for manufacturing a wiring board according to the present invention, a precision pressing having a convex reverse wiring pattern from the metal film side formed on the surface of the organic insulating base material on which an extremely thin metal film having a good spreadability is formed. After forming the wiring circuit groove on the substrate using a mold (die press), the precision stamping die is pulled up, and the metal is deposited in the groove formed by electroplating in the groove formed as described above. Since the wiring pattern is formed by polishing the plating layer until the resin layer of the organic insulating base material is exposed from the surface of the formed electroplating layer after depositing and filling the wiring pattern, this wiring pattern is It is formed in a state where it is buried in an organic insulating substrate. Thus, the wiring pattern is formed on substantially the same plane as the surface of the organic insulating substrate. Thus, since the wiring pattern does not substantially protrude from the surface of the organic insulating base material, no solder bridge is generated between the wiring patterns even when the pitch width of the wiring pattern is narrow. Further, since the wiring pattern is formed by polishing the plating layer, the surface state can be made uniform. Moreover, since this wiring pattern is formed on substantially the same plane as the organic insulating base material, even if a solder ball is placed on this wiring pattern, there is no corner at the pad bottom, so a void is formed in this part. It will not be done. Therefore, the reliability of connection when using solder balls can be made very high.

Next, the manufacturing method of the wiring board of the present invention and the wiring board obtained by this method will be specifically described.
FIG. 1 is a diagram schematically showing a cross section of a substrate in each process when manufacturing a wiring board of the present invention.

In FIG. 1 (a), the organic insulating base material used in the present invention is indicated by reference numeral 10. The organic insulating substrate 10 can be formed of an organic material having electrical insulation. The organic insulating substrate 10 can be made of, for example, a liquid crystal polymer, an epoxy resin, polyimide, a cured or uncured laminated paste. Here, examples of the laminating paste include X glue manufactured by Yodogawa Paper Mill.

The organic insulating substrate 10 is usually flexible. For example, epoxy resin, polyimide resin, cured laminated paste and the like are often hard, and when such a hard resin is used, for example, epoxy resin cured precursor, polyamic acid, uncured laminated By using a paste or the like, it can be used in a soft state when using a precision stamping die and cured when heated or exposed in a later step. When using the organic insulating substrate 10 while curing the resin as described above, a support can be used to apply the uncured resin. In FIG. 1 (a), the support is indicated by the number 11. The support 11 supports the organic insulating substrate 10 in the process of forming the organic insulating substrate 10, and does not need to be particularly insulating. As such a support 11, for example, a metal foil such as an electrolytic copper foil or an aluminum foil, a synthetic resin film, or the like can be used. This support 11 holds the form of the organic insulating base material 10 whose form has not been determined, for example, the curing has not been completed, and is peeled off after the form of the organic insulating base material 10 has been determined. It is also possible to form a part of the organic insulating substrate 10 while leaving the support 11.

  Therefore, the organic insulating substrate 10 used in the present invention is not limited as long as the layer in which the concave portion is formed by the pressing die has the insulating property and the flexibility as described above. It may be a layer structure or a multilayer structure.

  The thickness of the organic insulating substrate 10 as described above may be any thickness as long as a recess can be formed by a pressing die, and the depth of the formed recess is usually about 5 to 30 μm. The thickness of the portion where the concave portion of the conductive substrate 10 is formed should be equal to or greater than the depth of the concave portion, and when the single-layer organic insulating substrate 10 is used, the thickness of the organic insulating substrate 10 is Usually, the thickness is about 12.5 to 75 μm, and when the organic insulating base material 10 having a multilayer structure is used, the thickness of the surface layer where the concave portion is formed is usually about 12.5 to 50 μm.

In the present invention, the metal thin film 12 is formed on one surface of the organic insulating substrate 10.
The metal thin film 12 formed here is formed of a metal with good extensibility that has a thickness of usually 0.1 to 1 μm, preferably 0.2 to 0.8 μm. By forming the metal thin film having the thickness as described above, defects such as cracks are hardly generated in the metal thin film even when the pressing die is pressed. From the viewpoint of preventing breakage when the metal thin film 12 is pressed by a pressing die, it is preferable to employ a material having an elongation rate e of 0.07 or more, and to employ a material having an elongation rate e of 0.2 or more. preferable. Although the upper limit value of the elongation rate e is not particularly limited, empirically, the upper limit value is about 0.5. By using a metal thin film having such an elongation rate e, defects such as cracks are less likely to occur. Here, the elongation rate e of the metal thin film is a value obtained by dividing the stretched length until breaking when a metal thin film having a predetermined length is stretched at room temperature by the length of the original metal thin film, for example, 10 mm. The case where the metal thin film is broken at 13 mm will be described as an example. (13 mm−10 mm) / 10 mm = 0.3, and “0.3 (dimensionless)” is the elongation e of the metal thin film. .

In the present invention, the metal thin film having the above characteristics can be formed by, for example, the method described below.
The first method is a method of forming a metal thin film having good spreadability by electroless copper plating of the organic insulating substrate 10.

In this method, electroless copper plating is preferably performed after the activation treatment so that copper is likely to be deposited on the surface of the organic insulating substrate 10. As this activation treatment, a method in which a catalyst is adsorbed so that copper is easily deposited on the surface of the organic insulating substrate 10 by electroless copper plating is particularly preferable. For adsorption of such a catalyst, the surface of the resin forming the organic insulating substrate is first swollen and then the surface is treated with an oxidizing agent such as potassium permanganate to oxidize and remove the surface layer. This surface is neutralized and then treated using a conditioner such as MK-140 manufactured by Muromachi Technos. By treating in this way, the activity capable of adsorbing the catalyst can be imparted to the surface of the organic insulating substrate. After the catalyst adsorption activation treatment of the surface of the organic insulating base material in this way, for example, microetching is performed using a microetching solution containing an etching agent such as potassium persulfate to remove surface oxides, Next, a potassium persulfate residue that may remain on the surface of the organic insulating substrate is removed using an aqueous sulfuric acid solution.

For example, a metal deposition catalyst such as a Pd—Sn catalyst is adsorbed on the organic insulating base material whose surface has been adjusted as described above. Such adsorption of the Pd—Sn catalyst may be performed by immersing the organic insulating substrate in a solution containing the catalyst. At this time, the organic insulating substrate may be immersed in the Pd-Sn catalyst-containing solution at once, but a pre-dipping solution containing the Pd-Sn catalyst is prepared, and the organic insulating substrate is temporarily pre-dipped. After dipping in the liquid, the Pd—Sn catalyst-containing solution is less likely to be liquid-degraded by dipping again in the Pd—Sn catalyst-containing solution.

By soaking in the Pd—Sn catalyst-containing solution in this way, the Pd—Sn catalyst is adsorbed on the surface of the organic insulating substrate.
The organic insulating base material on which the Pd—Sn catalyst is adsorbed is pulled up and washed with water, so that most of the Sn adsorbed on the surface of the organic insulating base material is removed and Pd is adsorbed on the surface. become. In order to further increase the catalytic activity on the surface of the organic insulating substrate on which Pd is adsorbed, for example, after treatment with a sulfuric acid-based chemical such as KM-370 manufactured by Muromachi Technos, electroless copper plating is performed. A copper layer is formed.

Thus, the surface of the organic insulating substrate on which Pd is adsorbed exhibits high activity against electroless copper plating, and copper can be efficiently precipitated from the electroless copper plating solution. An electroless copper plating layer made of deposited copper exhibits excellent spreadability.

In the second method, a copper foil having a thickness of, for example, about 5 to 10 μm is laminated on the organic insulating substrate 10, and then the heat-treated annealed copper foil is usually 0.1 to 1 μm, preferably 0.00. This is a method of half-etching to a thickness of 08 to 0.5 μm. The excellent ductility of the copper foil is further improved by annealing the copper foil used here. In this method, a copper foil is laminated on the surface of the organic insulator substrate 10, and then heated and heat-treated. The heat treatment temperature is preferably set so that the elongation ratio e of the copper foil is 0.35 or more (35% or more). Specifically, the annealing temperature is usually in the range of 180 to 250 ° C. Set to the temperature inside.

  The copper foil thus laminated and annealed is half-etched to a predetermined thickness. As the half etching solution used here, a normal etching solution can be used, and the residual copper foil thickness can be adjusted by adjusting the etching time. In general, rolled copper foil is preferably used here because rolled copper foil is more excellent in spreadability than electrolytic copper foil.

The third method is a method of forming a metal thin film having excellent spreadability by sputtering copper to a thickness of 0.1 to 1 μm on the organic insulating substrate.
That is, in this method, a sputtering copper layer having a predetermined thickness is formed by sputtering copper on the surface of the organic insulating substrate using a sputtering apparatus. The sputtered copper layer thus formed exhibits excellent spreadability.

The fourth method is a metal thin film obtained by forming a Zn plating layer on the surface of the sputtered copper layer formed as described above and then annealing it. Thus, by forming a galvanized layer on the surface of the sputtered copper layer and heating the laminate of the copper layer and the galvanized layer thus obtained to a temperature usually in the range of 160 to 280 ° C., The copper and zinc forming the layer diffuse together to form an alloy layer. As described above, the thickness of the alloy layer is usually 0.1 to 1 μm, preferably 0.2 to 0.8 μm.

  When this method is employed, the thickness of the sputtered copper layer is usually 0.07 to 0.7 μm, preferably 0.14 to 0.56 μm, and the thickness of the galvanized layer is usually 0.00. It is 03-0.3 micrometer, Preferably it is 0.06-0.24 micrometer. And the ratio (Cu: Zn) of the thickness of a sputtering copper layer and the thickness of a zinc plating layer is usually in the range of 8: 2 to 6: 4, preferably 7.5: 2.5 to 6.5: Set within the range of 3.5. A metal thin film having such a thickness ratio, that is, a ratio of copper to zinc in the alloy layer, has very excellent spreadability, and defects such as cracks are hardly generated.

The fifth method is a method of forming a Zn—Al based superplastic alloy layer on the surface of the organic insulating substrate. The Zn-Al superplastic alloy used here has a very good spreadability, and such a Zn-Al superplastic alloy forms a sputtering alloy layer using, for example, a normal sputtering apparatus. can do. As described above, the thickness of this Zn—Al-based superplastic alloy layer is usually 0.1 to 1 μm, preferably 0.2 to 0.8 μm.

Furthermore, not only the Zn-Al based superplastic alloy as described above, but also the above Zn using a superplastic alloy such as Fe-Cr-Ni based alloy, Ti-Al-V based alloy, Al-Mg based alloy, etc. -By forming a superplastic alloy layer in the same way as in the case of an Al-based superplastic alloy, a metal thin film having excellent ductility equivalent to that of a superplastic alloy layer formed from a Zn-Al-based superplastic alloy is formed. can do.

  Furthermore, in the present invention, in addition to the above method, other methods capable of forming a metal thin film having the same characteristics as the metal thin film excellent in spreadability formed by the above method can also be adopted. Of course. For example, when polyimide is employed as the organic insulating base material, the direct metalizing method can be applied.

FIG. 1 (b) shows a cross section of the substrate on which the metal thin film 12 having good extensibility formed as described above is formed on the surface of the organic insulating substrate 10. The support 11 shown in FIG.
Is omitted in FIG. 1 (b). The support 11 is an arbitrary layer, and even when the support 11 is disposed, it can be peeled off and removed at any time point when the organic insulating base material 11 exhibits self-formability. In the drawings shown below, the description is omitted as in FIG.

In the method for manufacturing a wiring board according to the present invention, as shown in FIG. 1 (c), the metal thin film 12 having excellent extensibility formed on the surface of the organic insulating base material 10 as described above is precision-molded. A recess is formed in the malleable metal thin film 12 by abutting and pressing 30.

  As shown in FIG. 2, the precision stamping die 30 used in the present invention is generally a stamping die base 31 that forms this precision stamping die, and a stamping pattern 33 formed on the surface of the stamping die base 31. It has. Further, the precision pressing die 30 may have a heating means (not shown).

  The pressing die base 31 holds a pressing die pattern 33 formed on the precision pressing die 30, and usually has a flexibility such as a hard member such as a metal or a resin plate or a resin film or a resin sheet. It is formed from the soft member which has.

The precision mold 30 used in the present invention has a mold pattern formed on the surface of the mold base 31 as described above.
This mold pattern is formed by selectively depositing metal on the surface of the mold base 31 or by forming a pattern on the surface of the mold base 31 and selectively etching this pattern as a masking material. Thus, it can be formed by a method of forming a stamp pattern.

  For example, a photosensitive resin layer is formed on the surface of the mold base 31, and a desired pattern is formed by exposing and developing the photosensitive resin layer, and plating is performed using this pattern as a masking material. Thus, a metal pattern can be deposited to form a stamp pattern. In this method, when the photosensitive resin layer is exposed and developed, the photosensitive resin is exposed and developed so that a portion of the wiring pattern to be formed is opened. Next, the pattern made of the cured photosensitive resin thus formed is used as a masking material to perform a plating process to form a stamp pattern with the deposited metal, and then the masking material made of the cured photosensitive resin is removed. As a result, a pressing pattern can be formed. This stamp pattern is formed of metal deposited by plating as described above. Here, examples of the metal that forms the stamp pattern 33 include metals that can be deposited by plating such as nickel, copper, chromium, tin, zinc, silver, and gold. The pressing pattern 33 can be formed by performing the selective plating process as described above at least once. However, when forming the pressing patterns having different heights, the selective plating process is performed as described above. By performing the process twice or more, it is possible to form a stamp pattern having different heights depending on the number of plating processes.

  For example, when forming a stamp pattern using a metal that can be etched, a photosensitive resin layer is formed on a metal surface such as copper, iron, or nickel, and the photosensitive resin layer is exposed and developed. Thus, a masking material made of a photosensitive resin is formed, and a metal mold is etched using this masking material to form a pressing pattern. In this method, since the stamp pattern is formed by etching the metal, the shape of the masking material made of the photosensitive resin cured body is substantially the same as the stamp pattern to be formed. The etching agent used in this method can be appropriately selected according to the type of metal to be etched.

  By performing the etching process as described above at least once, a metal stamp pattern can be formed. Moreover, when forming the pressing pattern having different heights, the etching process as described above is performed twice or more.

  In the present invention, the stamp pattern can also be manufactured by forming a predetermined pattern by etching a metal in accordance with the above-described method, and then forming a plating layer on the surface of this pattern.

  The stamp pattern 33 formed as described above can be formed at such a height that no crack is formed in the metal thin film having excellent spreadability by the stamp. The height of the stamp pattern 33 is usually 1 to 40 μm, preferably 5 to 30 μm. Defects such as cracks are less likely to occur in the metal thin film having excellent spreadability even when the stamping die is formed with a pattern having a height as described above, and the wiring pattern formed when polishing in a subsequent polishing step It becomes difficult to break.

The cross-sectional shape of the pressing pattern formed as described above can be various shapes such as a rectangular shape, a trapezoidal shape, and a triangular shape.
In the present invention, as shown in FIG.1 (d), the precision pressing die 30 as described above is brought into contact with the metal thin film 12 and pressed, so that the organic insulating substrate 10 is formed from the metal thin film 12 side with good spreadability. A concave portion 20 having a shape corresponding to the pressing pattern 33 is formed in the metal thin film 12 having excellent spreadability toward the deep portion.

That is, as shown in FIG. 1 (d), a precision stamping die 30 is arranged on a metal thin film 12 with good spreadability, and the mold pattern 33 is spread while the spreadable metal thin film 12 is spread. The concave portion 20 corresponding to the shape of the stamp pattern 33 is formed by being pressed into the organic insulating substrate 10 in the above. By pushing the stamp pattern 33 in this way, the metal thin film 12 penetrates into the organic insulating base material 10 while extending, but since this metal thin film 12 has excellent spreadability as described above, it is cracked. The inner wall surface of the formed recess 20 is covered with a stretched stretchable metal thin film.

  When forming the recess 20 using the precision stamping die 30 as described above, when the metal thin film 12 forms a circuit, the line width of the circuit surface is d, the depth is h, and the metal thin film is broken. When the elongation percentage is e, it is preferable that the metal thin film has a relationship represented by the following formula (1).

  Thus, the elongation e of the thin metal film 12 with good spreadability, the line width d (μm) and the depth h (μm) of the formed circuit surface satisfy the relationship represented by the above formula (1). By doing so, the wiring pattern can be formed satisfactorily.

In the present invention, the pressure applied to the precision pressing die 30 depends on the type of the organic insulating substrate 10, but is usually 0.1 to 20 kg / mm ² , preferably 0.2 to 10 kg / mm ² . Set within range. Such pressurization may be performed under heating. The heating temperature in this case is usually set to a temperature in the range of 100 to 300 ° C, preferably 150 to 200 ° C. By pressurizing under heating in this way, the mold pattern 33 formed on the precision stamping die 30 can easily enter the organic insulating substrate 10, and the organic insulating substrate 10 is formed by heating. The curing reaction of the resin can proceed rapidly. Therefore, the form of the organic insulating substrate 10 is fixed by pressurizing under heating as described above.

The pressing time of the precision pressing die 30 under such conditions is usually 0.2 to 60 minutes, preferably 0.3 to 30 minutes.
After pressing the precision pressing die 30 as described above, the precision pressing die 30 is pulled up and removed.

After the recess 20 is formed as described above, a metal plating layer 22 thicker than the depth of the recess 20 is formed on the metal thin film 12 by plating.
In the present invention, the metal plating layer 22 is preferably formed by electroplating. Since the metal thin film 12 is present on the surface of the organic insulating base material 10, electroplating in this step can be performed smoothly.

As shown in FIG.1 (e), in this invention, the metal plating layer 22 thicker than the depth of the recessed part 20 is formed by electroplating. That is, the depth of the recess 20 formed in the above process is usually 1-40 μm, preferably 5-30 μm, which is the height of the stamp pattern 33. Is generally 101 to 200% thick, preferably 110 to 150% thick with respect to the depth h of the recess 20. By setting the thickness of the electroplating layer with respect to the depth of the recess in the above range, the recess can be completely filled with the deposited metal.

  By forming an electroplating layer having such a thickness, the recess 20 can be filled with the deposited metal, and the surface of the metal thin film 12 where the recess 20 is not formed is also covered with the electroplating layer. Is called.

Here, the electroplating layer 22 is preferably a copper electroplating layer. The copper concentration of the plating solution used in this electroplating is usually in the range of 5-30 g / liter, preferably 8-25 g / liter, and the current density when using such a plating solution is usually The temperature is 0.5 to 8 A / dm ² , preferably 1 to 6 A / dm ² , and the temperature of the plating solution is usually 19 to 28 ° C., preferably 21 to 26 ° C.

Under such conditions, the electroplating time is usually 1 to 10 minutes, preferably 2 to 8 minutes.
In the present invention, after the metal plating layer 22 is formed by electroplating as described above, FIG.
As shown in (g), the metal plating layer 22 is polished until the organic insulating substrate 10 is exposed from the surface of the metal plating layer 22, and the plating metal 24 is formed in the recess 20 in the organic insulating substrate 10. A filled wiring pattern 26 is formed.

That is, in this polishing step, the metal plating layer 22 is polished and removed from the surface of the metal plating layer using the polishing tool 35, and the metal thin film 12 on the surface of the organic insulating substrate 10 is also polished and removed. . Therefore, by polishing in this way, the metal thin film 12 is removed from the surface of the organic insulating substrate 10 and the organic insulating substrate 10 is exposed as shown in FIG. On the other hand, since the recess 20 is embedded in the organic insulating base material 10, the plated metal 24 filled in the recess 20 and the extensible metal thin film 12 below the organic metal base material are not polished. The wiring pattern 26 is buried in 10. First, rough polishing is performed with the # 200 to # 320 brushes until the surface of the organic insulating substrate 10 is exposed, and then the surfaces are adjusted with the # 600 to # 800 buffs.

  In the next finish polishing step, both chemical polishing and physical polishing can be employed. However, physical polishing is preferable because it simplifies the process. When physical polishing is employed, a normal polishing brush and polishing buff can be used as the polishing tool 35, and an abrasive composition containing abrasive grains can also be used. Examples of the polishing brush and the polishing buff that can be used here include a polishing brush and a polishing buff having a roughness of # 1500 or more, preferably # 2500 or more.

  Moreover, when using an abrasive | polishing agent composition, the composition containing the alumina abrasive grain whose average particle diameter of an abrasive grain is 1 micrometer or less, Preferably it is 0.3 micrometer or less can be used. It is preferable to perform polishing sequentially using the polishing tools 35 having different roughness as described above. By sequentially using such a polishing tool 35, polishing can be performed efficiently, and excessive polishing is not performed, so that the formed wiring pattern is not damaged.

  As described above, the rough polishing is preferably performed until the surface of the organic insulating substrate 10 is almost exposed. After rough polishing in this way, buff finish polishing is performed to finish the copper pattern surface smoothly.

  By buffing in this way, the metal plating layer 22 and the metal thin film 12 remaining on the surface of the organic insulating substrate 10 are removed and embedded in the organic insulating substrate 10 to form a large number of wiring patterns 26. Can be formed. Between the wiring patterns thus formed, only the organic insulating substrate 10 exists, and the formed many wiring patterns 26 are in an electrically independent state from the adjacent wiring patterns 26.

Further, the upper end portion 27 of the wiring pattern 26 formed by polishing as described above is flush with the surface of the organic insulating substrate 10.
The wiring pattern 26 made of plated metal and metal thin film with good spreadability formed in this way has an upper end portion 27 formed on the same surface as the surface of the organic insulating base material and exposed. The other part of the pattern is formed by being embedded in the organic insulating substrate. When this wiring board is used, the upper end portion 27 of the wiring pattern 26 formed on the same surface as the surface of the organic insulating base is used as a connection portion. In the wiring board having such a configuration, solder is used. There is no flow.

  Although the wiring board obtained by polishing in this way can be used as it is, the wiring pattern exposed on the surface of the organic insulating substrate 10 with a metal different from the metal forming the wiring pattern 26. The upper end 27 of 26 is preferably plated.

Here, as the different metal constituting the layer formed by the plating treatment, it is preferable to use a metal that improves the wettability of the solder used in the subsequent step.
When the wiring pattern 26 is manufactured by depositing copper by electroplating in the present invention, the upper end 27 of the wiring pattern 26 is tin-plated, gold-plated, nickel-plated, gold-nickel-plated, solder-plated, lead-free. Solder plating can be applied. In particular, in the present invention, it is preferable to perform tin plating or gold plating so that the solder wettability and the anticorrosive effect are compatible.

FIG. 1 (i) shows the wiring board of the present invention plated as described above, and the plating layer is denoted by reference numeral 28.
For example, when tin plating is performed, the thickness of the tin plating layer is usually in the range of 0.1 to 0.7 μm, preferably 0.2 to 0.5 μm.

  Such a tin plating layer is preferably formed by electroless tin plating or electrotin plating. As the electroless tin plating solution that can be used here, a tin plating solution that is usually used can be used. In such a tin plating solution, the tin concentration is usually 15 to 35 g / liter, preferably 19 to 29 g. / Liter.

For example, the metal plating layer 28 formed as described above is, for example, a gold plating layer or a tin plating layer, and when this plating layer is formed by electroplating, as shown in FIG. It is formed protruding from the surface of the substrate 10. In order to keep the surface smooth, the thickness of the formed plating layer is preferably 0.5 μm or less. Further, for example, when the above tin plating layer is formed by electroless tin plating, as shown in FIG. 1 (j), the copper on the surface of the wiring pattern 26 is replaced with tin during the electroless tin plating, and the electroless tin plating is performed. A layer 29 is formed, and the upper surface of the electroless tin plating layer 29 is formed on the same surface as the surface of the organic insulating substrate 10. Thus, the metal plating layer is preferably formed by substitutional electroless plating.

  In the wiring board of the present invention formed in this manner, the surface of the recess 20 formed in the organic insulating base material 10 is filled with the plating metal 24 via the metal thin film 12, and the wiring pattern 26 is formed. .

Furthermore, it is preferable to form a metal plating layer 28 made of a metal different from the plating metal 24 filled in the recess 20 on the surface of the wiring pattern 26 formed in this way.
In the wiring board of the present invention, since the wiring pattern 26 is buried in the organic insulating base material 10, even if the interval between the wiring patterns 26 is very fine, a short circuit is caused between the adjacent wiring patterns 26. It is never formed. Therefore, the wiring substrate of the present invention can be formed with a narrow pitch width of the wiring pattern 26. In the present invention, the wiring pattern can be manufactured as long as the pitch width of the wiring pattern is 20 μm or more. It is suitable for manufacturing a wiring board of ˜300 μm. Furthermore, the width of the wiring pattern in the wiring board of the present invention is usually 5 to 150 μm, preferably 15 to 100 μm.

  According to the method for manufacturing a wiring board of the present invention, a wiring board in which a wiring pattern is embedded in an organic insulating base material can be formed. That is, the concave portion 20 formed in the organic insulating base material 10 is filled with a plating metal through the metal thin film 12 having good spreadability, and the upper end portion 27 of the wiring pattern 26 is an organic insulating base material. It is formed on the same plane as 10 surfaces. Such a wiring pattern 26 is embedded in the organic insulating base material 10 through the metal thin film 12 having good spreadability, and the wiring pattern 26 is formed by biting into the organic insulating base material 10. The adhesion between the conductive substrate 10 and the wiring pattern 26 is high. Further, by forming the wiring pattern 26 on the same surface as the organic insulating base material 10 in this way, by using the wiring pattern 26 as a solder ball pad, the solder ball pad area becomes uniform and the solder ball pad area becomes uniform. There is no discrepancy in the height of the ball. Furthermore, when such a wiring pattern is used as a solder ball pad, there is no corner portion in the solder ball pad, so that no voids are formed when soldering, and the electric power using the solder ball is not formed. Connection reliability is improved.

〔Example〕
Next, the method for manufacturing a wiring board and the wiring board according to the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.

An epoxy resin having a glass transition temperature Tg = 180 ° C. was applied to an electrolytic copper foil having a thickness of 12 μm as a support to a thickness of 20 μm.
The epoxy resin layer thus formed is swollen, oxidized and removed with an oxide, and after neutralization, the soil is removed with a conditioner and the catalyst adsorption is activated, and the oxide is removed by microetching with potassium persulfate. The persulfuric acid residue was removed with sulfuric acid. The processing time in these steps was several minutes each.

  Then, after pre-dip treatment for protecting the catalyst bath, the Pd—Sn catalyst was adsorbed on the surface of the epoxy resin. The catalyst layer thus formed is washed with water to remove Sn, and further treated with sulfuric acid chemicals to promote catalytic activity, and then the catalyst activated epoxy resin is treated with an electroless copper plating solution for 15 minutes. As a result, a copper film having a thickness of 0.4 μm was formed. After forming the copper film in this manner, washing with water formed a 35 mm × 40 mm double layer substrate (with an electrolytic copper foil support) having an electroless plating layer having a thickness of 0.4 μm on the surface of the epoxy resin layer. . The elongation ratio e of the electroless plating layer of the two-layer base material separately prepared by the same method was 0.1.

15 mm x 15 mm gold-plated precision press with a wiring height of 10 μm and a trapezoidal pattern formed on a 180 μm pitch (line width of 100 μm, spacing of 80 μm) on the surface of the electroless plating layer having a thickness of 0.4 μm. A mold is placed, and this gold-plated precision stamping die is used with a pulse heat thermocompression bonding apparatus (manufactured by Nippon Avionics Co., Ltd.) with a 3 mm wide heat tool at a pressure of 0.2 kg / mm ^2.
A thermocompression bonding was performed at 0 ° C. for 19.8 seconds to form a concave portion corresponding to the convex portion formed on the gold-plated precision stamping die on the surface of the 0.4 μm electroless copper plating layer of the two-layer base material.

  By using the gold-plated precision stamping die as described above, the convex portions formed on the gold-plated precision stamping die were formed as depressions (concave portions) of the two-layer base material. The depth h of the depression (recess) was 10 μm. Thus, no cracks or the like occurred in the electroless copper plating layer even when the depression (recess) was formed. In addition, the epoxy resin hardened | cured by pressurizing under heating as mentioned above.

Next, using a copper sulfate plating solution for through-hole plating with a copper concentration of 18 g / liter, the current density was set to 4 A / dm ² , and copper electroplating was performed at room temperature for 20 minutes with vigorous stirring. An electrolytic copper plating layer having a depth of 170% with respect to the depth h could be formed.

Next, the electrolytic copper plating layer thus formed was roughly polished from the surface with # 280 polishing paper, then leveled with # 600 polishing paper, and then finish-polished with # 1500 buffing to finish the resin. The electrolytic copper plating layer formed on the substrate surface was removed, and the electroless copper plating layer under the electrolytic copper plating layer was removed to expose the epoxy resin substrate.

  By polishing and removing the excess electrolytic copper plating layer in this way, a wiring pattern in which a copper electroplating metal was filled in a recess symmetrical to the pattern formed on the gold-plated precision stamp used was formed. The wiring pattern thus formed had a pitch width of 180 μm.

  Using the electroless tin plating solution (LT-34, manufactured by Rohm and Haas) on the wiring pattern formed as described above, electroless tin plating is performed under the conditions of 70 ° C. × 2.5 minutes. Copper having an average thickness of 0.5 μm was replaced with an electroless tin plating layer.

  Of the wiring patterns formed in this way, the wiring pattern made of electrolytic copper is formed so as to bite into the resin substrate, but the electroless tin plating layer formed thereon is also the same as the surface of the resin base material. It is formed on the surface. Moreover, it became the form which copper plating and tin plating adhered also to the electrolytic copper foil support body side used as a support body first, and the 2 metal board | substrate which is not electrically connected with the said pattern was obtained.

Laminated 10 μm thick tough pitch copper rolled copper foil with 50 μm liquid crystal polymer (all aromatic polyester resin orientation controlled), annealed at 180 ° C. for 1 hour, elongation of 35% or more (0.35 or more The rolled copper foil layer of the 35 mm × 40 mm two-layer laminate improved to (1) was half-etched so as to have a thickness of 1 μm. The elongation e of the rolled copper foil used was 0.12. Separately from this, a wiring circuit having a protrusion height of 5 μm and a pitch of 50 μm (line width 30 μm, interval 20 μm) formed (rectangular) 15 mm × A precision die made of silicon having a thickness of 15 mm and a thickness of 0.2 mm was prepared.

Placed on the surface of the copper layer of the resin substrate on which the 1 μm copper layer prepared as described above was formed, using a pulse heat thermocompression bonding apparatus (manufactured by Nippon Avionics Co., Ltd.), heat seal (super When the thermocompression bonding was performed at a pressure of 200 g / mm ² and 350 ° C. × 5 seconds using Imper, a wiring groove having a depth of 5 μm and a width of 30 μm could be formed on the two-layer substrate.

  In this way, the silicon precision stamping die was pressed under heating to form a recess, but no cracks or the like occurred in the rolled copper foil with good spreadability adjusted to a thickness of 1 μm as described above. .

Next, the precision stamping die is removed and copper electroplating is performed at room temperature for 15 minutes at a current density of 4 A / dm ² under strong stirring using a copper sulfate plating solution for through-hole plating with a copper concentration of 18 g / liter. An electrolytic copper plating layer having a thickness of 13 μm could be formed on the entire surface.

Next, the electrolytic copper plating layer thus formed was roughly polished from the surface with # 280 polishing paper, then leveled with # 600 polishing paper, and then finish-polished with # 1500 buffing to finish the resin. The electrolytic copper plating layer and the 1 μm-thick copper foil layer formed on the substrate surface were removed by polishing to expose the surface of the liquid crystal polymer as the resin substrate.

By polishing and removing the excess plating layer in this way, a copper electroplating metal was filled in a recess symmetrical to the pattern formed in the used silicon precision stamping die to form a wiring pattern. The wiring pattern thus formed had a pitch width of 50 μm.

Using the electroless tin plating solution (LT-34, manufactured by Rohm and Haas) on the wiring pattern formed as described above, electroless tin plating is performed under the conditions of 70 ° C. × 2.5 minutes. Copper having an average thickness of 0.5 μm was replaced with an electroless tin plating layer.

  Among the wiring patterns formed in this way, the wiring pattern made of electrolytic copper is formed so as to bite into the resin substrate made of liquid crystal polymer, but the electroless tin plating layer formed thereon is also made of liquid crystal polymer. It is formed on the same surface as the surface of the resin base material.

A precision stamping die in which 16 convex patterns having a wiring height of 5 μm and a pitch of 30 μm (line width of 18 μm, spacing of 12 μm) with a length of 10 mm were formed on silicon of 15 mm × 15 mm size was produced.
Separately, a Ni-Cr (Cr content 20 wt%) alloy was sputtered to a thickness of 250 mm on the surface of a 35 μm-thick polyimide film (trade name: Upilex S, manufactured by Ube Industries, Ltd.), and further 2000 mm. An organic insulating substrate with a sputtered metal layer corresponding to e = 0.15 was prepared by sputtering Cu to a thickness of 5 mm.

A precision stamping die is brought into contact with the surface of the sputtered metal layer of the organic insulating substrate with the sputtered metal layer prepared as described above, and a pulse heat thermocompression bonding apparatus (manufactured by Nippon Avionics Co., Ltd., TCW-125) is used. A pressure of 7550 g / mm ² was applied with a heat tool and thermocompression bonded at 300 ° C. for 19.8 seconds.

After cooling to room temperature, the heat tool was pulled up and the precision die was removed.
It was confirmed that a concave pattern having a depth of about 5 μm was formed on the surface of the sputter metal layer of the organic insulating substrate with a sputter metal layer. No cracks or the like were observed in the formed sputtered metal layer.

Using a copper sulfate plating solution for through-hole plating with a copper concentration of 15 g / liter, the solution temperature is adjusted to 22 ° C. on the organic insulating substrate with a sputter metal layer having a concave pattern formed as described above, and strong stirring is performed. A copper electroplating layer having a thickness of 8 μm was formed on the entire surface of the organic insulating substrate by performing copper electroplating at a current density of 3 A / dm ² for 12 minutes.

  Next, the surface of the electrolytic copper plating layer formed as described above was roughly polished with a # 280 polishing paper using a rotary type polishing machine, and the polyimide film surface as an organic insulating base material appeared. The abrasive paper was replaced with # 600 abrasive paper and polished to finely prepare the abrasive scratches. Further, while dripping a polishing liquid (Miller Co., Ltd.) in which abrasive grains having an average particle diameter of 1 μm are dispersed, polishing is performed with # 1500 polishing paper (manufactured by Marumoto Struers Co., Ltd.), and the polishing paper is # 2400. The polishing paper (manufactured by Marumoto Struers Co., Ltd.) was used, and final polishing was performed while dropping a polishing liquid in which abrasive grains having an average particle size of 0.3 μm were dispersed.

  As a result, a wiring board having a wiring pattern formed of copper at the same height as the polyimide film (organic insulating base material) having a smooth surface and gloss was obtained. The formed wiring pattern is symmetric with the convex pattern formed in the precision stamping die.

Next, the above-mentioned wiring board is placed in a gold plating bath (manufactured by EEJA, Temperex # 8400), and electroplating is performed at a plating solution temperature of 65 ° C. and a current density of 0.5 A / dm ² for 2 minutes.
As shown in FIG. 1I, a wiring substrate having a wiring pattern in which a gold plating layer having a thickness of 0.5 μm protrudes from the surface of the organic insulating base material on the wiring pattern was obtained.

  Although the gold plating is not on the same surface, there is no practical problem such as soldering.

  In the wiring board manufactured by the method of the present invention, the conductor is embedded in the organic insulating base material. Therefore, even when the resin having low copper plating adhesion strength is used as the substrate, the resin substrate and the conductor High adhesion is developed between the two. For this reason, the range of selection of resin that can be used as a base material for manufacturing a wiring board is widened, and it has good insulation performance, chemical resistance, heat resistance, and excellent electrical characteristics, but it has good wiring pattern and adhesion. A new wiring board can be manufactured using a resin that is thought to be difficult to use as a base material because it is low, and the desired characteristics are imparted to the wiring board obtained by selecting the resin base material Becomes easier.

Further, since the wiring board of the present invention has a structure in which the formed wiring pattern is embedded in the resin, no solder bridge occurs between the bottoms even if the pitch is fine.
In particular, the wiring board of the present invention has high fatigue resistance reliability of the solder connection portion even when mounted using solder balls as external terminals, and can establish highly reliable electrical connection.

1-1 is a figure which shows typically the cross section of the board | substrate in each process at the time of manufacturing the wiring board of this invention. 1-2 is a figure which shows typically the cross section of the board | substrate in each process at the time of manufacturing the wiring board of this invention. FIG. 2 is a diagram schematically showing a cross section of the precision pressing die used in the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Organic insulating base material 11 ... Support body 12 ... Metal thin film 20 ... Concave 22 ... Metal plating layer 24 ... Plating metal 26 ... Wiring pattern 27 ... Upper end Part 28 ... Plating layer 29 ... Electroless tin plating layer 30 ... Precision die 31 ... Piece base 33 ... Piece pattern 35 ... Abrasive tool

Claims (13)

  By contacting and pressurizing an organic insulating substrate and a precision mold having a stamp pattern formed on the surface of the stamp base on the surface of the metal thin film formed on the surface of the organic insulating substrate, From the metal thin film side toward the deep part of the organic insulating substrate, a recess having a shape corresponding to the stamp pattern formed on the precision stamp is formed, and then the recess formed on the metal thin film is formed. Form a metal plating layer thicker than the depth, fill the recess formed by the precision die with plating metal, and then polish the metal plating layer until the organic insulating substrate is exposed from the surface of the metal plating layer A method of manufacturing a wiring board, comprising forming a wiring pattern. The thickness of the metal thin film is in the range of 0.1 to 1 μm, and the elongation e of the metal thin film is 0.00.
2. The method of manufacturing a wiring board according to claim 1, wherein the wiring board is 07 or more.   The surface of the organic insulating substrate is activated and a metal thin film is deposited on the activated organic insulating substrate by depositing copper having a thickness of 0.1 to 1 μm by electroless copper plating. 2. The method for manufacturing a wiring board according to claim 1, wherein the wiring board is formed.   2. The metal thin film is formed by half-etching a copper foil that has been annealed after laminating a copper foil on the organic insulating base material to a thickness of 0.1 to 1 μm. Wiring board manufacturing method.   2. The method of manufacturing a wiring board according to claim 1, wherein a metal thin film is formed on the organic insulating base material by sputtering copper to a thickness of 0.1 to 1 μm. After sputtering copper on the organic insulator substrate, a Zn plating layer is formed on the surface of the sputtering copper layer, and then an annealing treatment is performed to form an alloy layer of sputtering copper and Zn, thereby forming a metal thin film. 2. The method for manufacturing a wiring board according to claim 1, wherein the wiring board is formed.   2. The method for manufacturing a wiring board according to claim 1, wherein a metal thin film is formed on the surface of the organic insulating base material by sputtering a Zn—Al based superplastic alloy.   2. The method for producing a wiring board according to claim 1, wherein the organic insulating substrate is a liquid crystal polymer, an epoxy resin, polyimide, a cured or uncured laminated glue. When the line width on the surface of the circuit formed by the precision pressing die is d (μm), the depth is h (μm), and the elongation to break of the metal thin film is e, the metal thin film is expressed by the following formula (1). 2. The method of manufacturing a wiring board according to claim 1, wherein the wiring board has a relationship represented by:

  2. The wiring according to claim 1, wherein an electroplating layer is formed on the metal thin film of the organic insulating substrate to a thickness of 101 to 200% with respect to the depth h of the formed recess. A method for manufacturing a substrate. After polishing the metal plating layer until the organic insulating substrate is exposed from the surface of the electroplating layer to form a wiring pattern in which the concave portion is filled with the plating metal on the organic insulating substrate, the formed wiring pattern 11. The method for manufacturing a wiring board according to claim 1, wherein a plating layer made of a metal different from the filling metal is formed on the surface.   A wiring board, wherein a surface of a recess formed in an organic insulating substrate is filled with a plating metal through a metal thin film to form a wiring pattern.   13. The wiring board according to claim 12, wherein the spreadable metal thin film is formed by processing a copper foil.

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