JP2009010398A - Method of manufacturing printed wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a printed circuit board, by which an amount of residual metal on a printed wiring board surface is reduced and the occurrence of migration is prevented. <P>SOLUTION: When the printed wiring board is manufactured through a plurality of etching processes, a conductive metal layer is selectively etched and removed and Ni metal forming a base metal layer is brought into contact with first processing liquid which dissolves it to be removed; Cr contained in the base metal layer and Cr remaining in an insulating film are passivated by being brought into contact with second processing liquid having different chemical composition from the first processing liquid and acting on Cr as base metal layer forming metal with higher selectivity than conductive metal; and the Cr, which is passivated, and remains on a top layer surface of the insulating film where a wiring pattern is not formed and has formed the base metal layer, is removed together with the insulating film top layer surface. Further, the insulating film where the wiring pattern is formed is brought into contact with a reducing solution containing organic acid etc., having reducibility. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a printed wiring board in which a wiring pattern is directly formed on the surface of an insulating film. More specifically, the present invention relates to a method for manufacturing a printed wiring board formed from a two-layer substrate film comprising an insulating film and a metal layer formed on the surface of the insulating film without an adhesive layer. .

Conventionally, a wiring board is manufactured using a copper-clad laminate in which a copper foil is laminated using an adhesive on the surface of an insulating film such as a polyimide film.
The copper-clad laminate as described above is manufactured by thermocompression bonding a copper foil to an insulating film having an adhesive layer formed on the surface. Therefore, when manufacturing such a copper-clad laminate, the copper foil must be handled alone. However, the thinner the copper foil, the weaker the waist, and the lower limit of the copper foil that can be handled alone is about 12 to 35 μm. The handling becomes very complicated. In addition, using an adhesive on the surface of the insulating film and forming a wiring pattern using a copper-clad laminate with a thin copper foil as described above, the adhesive used to adhere the copper foil Warp deformation of the printed wiring board occurs due to heat shrinkage. In particular, with the reduction in size and weight of electronic devices, printed wiring boards are becoming thinner and lighter, and such printed wiring boards have a three-layered copper-laminated laminate composed of an insulating film, an adhesive, and copper foil. It is becoming impossible to handle with a board.

  Therefore, instead of such a three-layered copper-clad laminate, a two-layered laminate in which a metal layer is directly laminated on the insulating film surface without using an adhesive is used. Such a laminate having a two-layer structure is produced by depositing a metal on the surface of an insulating film such as a polyimide film by vapor deposition or sputtering. And a desired wiring pattern can be formed by apply | coating a photoresist to the surface of the metal deposited as mentioned above, exposing and developing, and etching using the masking material which consists of a photoresist. In particular, the laminate having a two-layer structure is suitable for manufacturing a very fine wiring pattern in which the wiring pattern pitch width formed because the metal layer is thin is less than 30 μm.

By the way, in patent document 1 (Unexamined-Japanese-Patent No. 2003-188495), it forms with the plating method on the 1st metal layer (base material metal layer) and the 1st metal layer which were formed in the polyimide film by the dry-type film-forming method. In a method for manufacturing a printed wiring board, in which a pattern is formed by an etching method on a metal-coated polyimide film (base film) having a conductive second metal layer (conductive metal layer), an etching surface after the etching An invention of a method for manufacturing a printed wiring board is disclosed, in which the substrate is cleaned with an oxidizing agent. Example 5 of Patent Document 1 shows an example in which a nickel-chromium alloy is plasma-deposited to a thickness of 10 nm, and then copper is deposited to a thickness of 8 μm by a plating method.

When forming a wiring pattern using such a metal-coated polyimide film, first, the second metal layer on the surface (a layer made of a conductive metal such as copper) is etched into a desired pattern, and then The first metal layer (made of nickel, chromium alloy, etc.) needs to be etched, and an etching solution containing oxidizing properties such as potassium permanganate is used when etching the first metal layer. . It is believed that the components contained in the etching solution are removed by washing the printed wiring board with water after etching the first metal layer using the oxidizing solution in this way. In addition, even if the components contained in the etching solution remain, in the conventional wiring substrate, it has not been considered that these remaining components affect the characteristics of the substrate. However, as the pitch width of the wiring patterns is gradually narrowed, it has been clarified that when a voltage between wiring patterns having such a narrow pitch is applied, the insulation resistance value between the wiring patterns tends to fluctuate. Such fluctuations in the insulation resistance value are due to metal residues on the surface of the polyimide substrate. However, such fluctuations in the insulation resistance value such as migration may depend on the metal content on the surface of the insulation film. all right.

  Furthermore, such a printed wiring board includes a base metal made of a metal such as chromium or nickel between a conductive metal layer forming a wiring pattern made of copper or a copper alloy and a polyimide film which is an insulating film. In order to form a wiring pattern from a composite metal layer composed of many kinds of metals, the metal that forms this composite metal layer is eluted through a plurality of etching processes using different etching solutions. It is necessary to make it. In particular, in order to etch a base metal layer containing a metal such as chromium or nickel, it is necessary to use an etching solution containing an oxidizing inorganic compound such as potassium permanganate. It has been found that the oxidizable inorganic compound (metal, salt, metal oxide, etc.) contained in is likely to remain on the formed wiring pattern or insulating film. The trace amount of inorganic compound remaining on the wiring pattern or insulating film thus formed contaminates the liquid agent used in the subsequent process of manufacturing this printed wiring board and remains on the printed wiring board until the end. Sometimes. The metal or inorganic compound derived from the remaining etching solution may cause migration that occurs between the wiring patterns. Further, in order not to deteriorate the characteristics of the processing solution in the subsequent process following this process, It is necessary to remove these metals as much as possible.

However, these metals or inorganic compounds are difficult to remove only by washing with water. Furthermore, in the recent printed wiring board in which the wiring pattern is very fine pitch, by continuing washing with running water for a long time, it is caused by water pressure or the like. Deformation of the substrate (wiring) is likely to occur, and in order to completely remove such metals or inorganic compounds, it is necessary to continue washing with water for a long time, which makes the production line longer and reduces the productivity. Has the problem.
JP 2003-188495 A

  In the present invention, when a voltage is continuously applied for a long time to a printed wiring board formed using a base film (ultra-thin metal-coated polyimide film) in which an insulating film is coated with an ultra-thin metal layer, An object of the present invention is to eliminate a problem peculiar to a printed wiring board using an ultrathin metal-coated insulating film in which an insulation resistance is lowered.

  That is, the present invention uses a substrate film (metal-coated polyimide film) in which an ultrathin metal layer is formed by sputtering or the like on at least one surface of an insulating film such as a polyimide film. It aims at providing the method of manufacturing a difficult printed wiring board.

The method for producing a printed wiring board of the present invention includes an insulating film, a base metal layer formed on at least one surface of the insulating film, and a conductive metal layer formed on the base metal layer. A plurality of etching steps including a step of selectively etching the conductive metal in the conductive metal etching step of mainly dissolving the conductive metal and a base metal etching step of mainly dissolving the base metal. After manufacturing a printed wiring board,
The conductive metal layer is selectively removed by etching, and the conductive metal layer is removed by contacting with the first treatment liquid that dissolves the Ni metal forming the base metal layer.
The base metal layer is brought into contact with a second processing liquid that has a different chemical composition than the first processing liquid and acts with high selectivity for Cr, which is a base metal layer forming metal, compared to the conductive metal. In addition to passivating Cr contained in the film, passivating Cr remaining on the insulating film, and forming a base metal layer remaining on the surface of the insulating film on which the wiring pattern is not formed Removing the passivated Cr together with the surface of the insulating film;
The insulating film on which the wiring pattern is formed is further brought into contact with a reducing aqueous solution containing a reducing organic acid or a salt thereof.

Furthermore, in the method for producing a printed wiring board of the present invention, an insulating film, a base metal layer formed on at least one surface of the insulating film, and a conductive metal layer formed on the base metal layer are provided. The wiring pattern is selectively etched through a plurality of etching steps including a conductive metal etching step that mainly dissolves the conductive metal and a base metal etching step that mainly dissolves the base metal. After forming
Removing the Ni metal that forms the base metal layer by contacting with the first treatment solution that dissolves the Ni metal;
Then, after contacting with a microetching solution that selectively dissolves the conductive metal,
The wiring pattern has a chemical composition different from that of the first treatment liquid, and is brought into contact with a second treatment liquid that acts with high selectivity on Cr, which is a base metal layer forming metal, rather than on a conductive metal. Forming a base metal layer remaining on the surface layer of the insulating film that is not formed and removing the passivated Cr together with the surface layer of the insulating film;
It is preferable that the insulating film on which the wiring pattern is formed is further brought into contact with a reducing aqueous solution containing a reducing organic acid or a salt thereof.

  In the method for producing a printed wiring board of the present invention, after the metal layer of the base film is selectively removed by an etching method to form a wiring pattern, the metal forming the base metal layer is dissolved and / or dissolved. Alternatively, it is preferable to treat with a treatment liquid such as passivatable potassium permanganate, and then contact with a reducing aqueous solution containing a reducing substance.

  Furthermore, in the method for producing a printed wiring board of the present invention, the base film is treated with a first treatment liquid capable of dissolving Ni contained in the base metal layer, and then contained in the base metal layer. Treated with a second treatment solution capable of dissolving Cr and removing the base metal layer of the insulating film, and removing the sputtering metal remaining on the surface of the insulating film where the wiring pattern is not formed together with the surface of the insulating film Further, it is preferable to contact with a reducing aqueous solution containing a reducing substance.

The printed wiring board of the present invention is a printed wiring pattern formed by selectively etching a base metal layer and a conductive metal layer formed on at least one surface of an insulating film in a plurality of etching steps. A wiring board, wherein the residual amount of metal derived from the etching solution in the printed wiring board is 0.05 μg / cm ² or less.

Furthermore, the printed wiring board of the present invention is formed such that the width of the lower end portion of the conductive metal layer in the cross section of the wiring pattern is smaller than the width of the upper end portion of the base metal layer in the cross section. It is preferable that the metal residual amount derived from the etching solution in the substrate is 0.05 μg / cm ² or less.

In the printed wiring board of the present invention, the base metal layer constituting the wiring pattern is formed so as to protrude in the width direction from the conductive metal layer constituting the wiring pattern, and etching in the printed wiring board is performed. The residual metal amount derived from the liquid is preferably 0.05 μg / cm ² or less.

Furthermore, in the printed wiring board of the present invention, the thickness of the insulating film in the portion where the wiring pattern of the insulating film is not formed is 1 to 100 nm thinner than the thickness of the insulating film where the wiring pattern is formed. In addition, the residual amount of metal derived from the etching solution in the printed wiring board is preferably 0.05 μg / cm ² or less.

In particular, in the present invention, the residual amount of metal derived from the etching solution in the printed wiring board is preferably in the range of 0.000002 to 0.03 μg / cm ² .
The semiconductor device of the present invention is characterized in that an electronic component is mounted on a printed wiring board that has a very small amount of metal derived from the etching solution as described above.

When selectively etching a base film having a base metal layer and a conductive metal layer on at least one surface of the insulating film, the conductive metal layer and the base metal layer are etched in a plurality of etching steps. It becomes necessary to do. In such an etching process, an etchant containing an oxidizing compound such as potassium permanganate, which is mainly used for etching the base metal layer, is difficult to be removed only by the cleaning process after the etching process. . Accordingly, in a printed wiring board manufactured through a normal water washing process, a trace amount of metal such as manganese derived from the above etching solution remains, and in the normal water washing process, the remaining amount of metal derived from the etching liquid is reduced to 0. It cannot be less than 0.05 μg / cm ² .

In the present invention, by selectively etching the base film in which the base metal layer and the conductive metal layer are laminated in this order on at least one surface of the insulating film, the base metal layer and the conductive metal layer are used. An aqueous solution containing a reducing substance containing an oxidizing metal or metal compound derived from an etching solution such as manganese contained in an etching solution used for etching a base metal layer after forming a wiring pattern It is processed using. By treating with an aqueous solution containing such a reducing substance, the metal or metal compound derived from the etching solution is very easily removed by washing with water, and the etching solution-derived metal remains on the surface of the printed wiring board after washing with water. the amount of the 0.05 [mu] g / cm ² or less, preferably to within the range of 0.000002~0.03μg / cm ^2. After the wiring pattern is formed in this manner, the residual amount of the metal derived from the etching solution can be remarkably reduced by washing the surface with an aqueous solution containing a reducing substance, which is used in the subsequent steps. The chemical solution is not contaminated, and deterioration of the appearance and quality of the printed wiring board of the present invention can be effectively prevented. Furthermore, it is possible to reduce the temporal change in the insulation resistance value between the wiring patterns, and it is possible to obtain a highly reliable printed wiring board and circuit board.

In the method for manufacturing a printed wiring board of the present invention, the substrate on which the wiring pattern is formed through a plurality of etching steps is washed with an aqueous solution containing a reducing substance. By cleaning with such a reducing substance-containing aqueous solution, the metal derived from the etching solution adhering to the substrate surface can be removed very efficiently. That is, when manufacturing the printed wiring board of the present invention, a base metal layer and a conductive metal layer formed on the surface of the base metal layer are formed on at least one surface of the insulating film. Using the material film, the base metal layer and the conductive metal layer are selectively etched by a plurality of etching processes using different etching solutions to form a wiring pattern, which is on the surface of the insulating film. When selectively etching the base metal, an etching solution containing an oxidizing metal compound such as potassium permanganate or sodium permanganate is used. For this reason, a small amount of metal derived from the etching solution remains on the surface of the printed wiring board obtained, and migration or the like is likely to occur between the wiring patterns due to such a small amount of residual metal derived from the etching solution. In addition, such residual metal also causes contamination of processing liquids used in later processes. Such residual metal derived from the etching solution is difficult to be removed by washing with water. Since the printed wiring board as described above is continuously manufactured in the form of a long tape, the process assigned to the water washing process is limited, and depending on the water washing in the normal printed wiring board manufacturing process, the printed wiring board The remaining amount of metal derived from the etching solution on the substrate surface cannot be reduced as defined in the present invention.

  The present invention has been made based on the finding that by using a reducing aqueous solution containing a reducing substance, the residual metal derived from such an etching solution can be efficiently removed, and at least the insulating film Using a base film having a conductive metal layer such as copper or copper alloy on one surface with a base metal layer such as nickel or chromium, a plurality of etching solutions of different types are obtained by a plurality of etching processes. After forming the wiring pattern by selectively etching the base metal layer and the conductive metal layer, the film surface is treated with a reducing aqueous solution containing a reducing substance such as a reducing organic acid. Thus, the metal derived from the remaining etching solution is removed.

  Accordingly, the surface of the printed circuit board manufactured by the method of the present invention has a remarkably small amount of metal derived from the etching solution, and no migration or the like occurs due to the residual metal. The processing solution used is not contaminated by residual metal.

  Thus, since the residual metal derived from the etching solution is efficiently removed from the surface of the printed wiring board of the present invention, the insulation resistance value between the wiring patterns even if the printed wiring board of the present invention is used for a long period of time. Is hard to fluctuate. Further, the deterioration of the wiring pattern due to the residual metal hardly occurs.

  Furthermore, since the electrical resistance value between the wiring patterns formed on the printed wiring board is stable over time as described above, the semiconductor device of the present invention can be used stably for a long time.

Next, the printed wiring board and the manufacturing method thereof of the present invention will be specifically described along the manufacturing method.
FIG. 1 is a diagram showing an example of a process when manufacturing a printed wiring board of the present invention. 2 is a cross-sectional view showing an example of a cross-sectional shape of a wiring pattern or the like in each step, and FIG. 3 is a schematic example of a cross-sectional shape of a wiring pattern in a printed wiring board manufactured by the method of the present invention. FIG. 2 and 3, common members are given common numbers, number 11 is an insulating film, number 12 is a base metal layer, and number 16 is a plating layer. Reference numeral 20 is a conductive metal layer, and reference numeral 22 is a masking material.

  In producing the printed wiring board of the present invention, a base film having a base metal layer and a conductive metal layer formed on the surface of the base metal layer is used on at least one surface of the insulating film. The

  Examples of the insulating film forming the base film include a polyimide film, a polyimide amide film, polyester, polyphenylene sulfide, polyether imide, a fluororesin, and a liquid crystal polymer. That is, these insulating films have heat resistance to such an extent that they are not deformed by heating, for example, when forming a base metal layer. Also, it has acid / alkali resistance to such an extent that it is not attacked by an etching solution used for etching or an alkaline solution used for cleaning. As such, a polyimide film is preferable.

Such an insulating film has an average thickness of usually 7 to 150 μm, preferably 7 to 50 μm, particularly preferably 15 to 40 μm. Since the printed wiring board of the present invention is suitable for forming a thin substrate, it is preferable to use a thinner polyimide film. In addition, the surface of such an insulating film may be subjected to a roughening treatment, a plasma treatment, or the like using a hydrazine / KOH solution or the like in order to improve the adhesion of the following base metal layer.

  A base metal layer is formed on the surface of such an insulating film. The base metal layer is formed on at least one surface of the insulating film. Therefore, in the present invention, the base metal layer and the conductive metal layer are laminated on one surface of the insulating film as the base film. Any film base (single-sided coated base film) or a film (double-side coated base film) in which the base metal layer and the conductive metal layer are laminated on both sides of the insulating film. A material film can be used.

In this base film, by providing the base metal layer, the adhesion of the conductive metal layer formed on the surface of the base metal layer to the insulating film is improved.
In the present invention, the base metal layer may be formed of a metal such as copper, nickel, chromium, molybdenum, tungsten, silicon, palladium, titanium, vanadium, iron, cobalt, manganese, aluminum, zinc, tin, and tantalum. it can. These metals may be used alone or in combination. Particularly in the present invention, the base metal layer is preferably formed of nickel, chromium, or an alloy containing these metals. Such a base metal layer is preferably formed on the surface of the insulating film by using a dry film forming method such as vapor deposition or sputtering. The thickness of such a base metal layer is usually in the range of 1 to 100 nm, preferably 2 to 50 nm. This base metal layer is for stably forming a conductive metal layer on this layer, and it is insulated with a kinetic energy that allows a part of the base metal to physically bite into the insulating film surface. It is preferably formed by colliding with a film. Therefore, in the present invention, the base metal layer is particularly preferably a base metal sputtering layer as described above.

  A conductive metal layer is formed on the surface of the base metal layer. This conductive metal layer is usually formed of copper or a copper alloy. Such a conductive metal layer can be formed by depositing copper or a copper alloy on the surface of the base metal layer by a plating method. Here, the plating method for forming the conductive metal layer includes a wet method such as an electroplating method and an electroless plating method, and a dry method such as a sputtering method and a vapor deposition method. May be formed. Moreover, a conductive metal layer can also be formed by combining a dry method and a wet method.

  Particularly in the present invention, the conductive metal layer is preferably formed by a wet plating method such as electroplating or electroless plating. The average thickness of the conductive metal layer thus formed is usually in the range of 0.5 to 40 μm, preferably 1 to 18 μm, more preferably 2 to 12 μm. When the above-described wet method and dry method are combined when forming the conductive metal layer, the sputtering conductive metal layer is generally formed on the surface of the base metal layer by, for example, sputtering. Thereafter, a wet process conductive metal layer is formed on the surface of the sputtering conductive metal layer. In this case, the average thickness of the sputtering conductive metal layer is usually in the range of 0.5 to 17.5 μm, preferably 1.5 to 11.5 μm. The total average thickness with the conductive metal layer is set within the above range. Note that the conductive metal layer formed in this way is inseparable even if the conductive metal deposition method is different, and acts equally when forming the wiring pattern.

  The total average thickness of the base metal layer and the conductive metal layer thus formed is usually in the range of 0.5 to 40 μm, preferably 1 to 18 μm, more preferably 2 to 12 μm. . The ratio of the average thickness of the base metal layer and the conductive metal layer is usually in the range of 1: 40000 to 1:10, preferably 1: 5000 to 1: 100.

  In producing the printed wiring board of the present invention, the base metal layer and the conductive metal layer are formed on at least one surface of the insulating film, and the base metal layer and the conductive metal layer are electrically conductive. A wiring pattern is formed by selectively etching the conductive metal layer in a plurality of etching steps.

  The wiring pattern is formed by forming a photosensitive resin layer on the conductive metal layer of the base film and exposing and developing a desired pattern on the photosensitive resin to form a pattern made of the photosensitive resin. The pattern can be formed by etching as a masking material.

This etching process mainly includes a conductive metal etching process for etching the conductive metal layer and a base metal etching process for mainly etching the base metal layer.
The conductive metal etching step is a step of etching copper or copper alloy forming the conductive metal layer, and the etching agent used here is an etching agent for copper or copper alloy which is a conductive metal (that is, Cu etching). Liquid).

Examples of such conductive metal etchants include an etchant mainly composed of ferric chloride, an etchant mainly composed of cupric chloride, and an etchant such as sulfuric acid + hydrogen peroxide. it can. Such an etching agent for the conductive metal is capable of forming a wiring pattern by etching the conductive metal layer with excellent selectivity, and this etching solution is used for the conductive metal layer and the insulating film. It also has a significant etching function for the intervening base metal.

  In this conductive metal etching step, the treatment temperature is usually 30 to 55 ° C., and the treatment time is usually 5 to 120 seconds. By performing etching using the conductive metal etchant as described above, a wiring pattern having a cross-sectional structure in which the conductive metal layer 20 is mainly etched is formed, for example, as shown in FIG.

  By conducting conductive metal etching as described above, the conductive metal layer 20 on the surface of the base film is mainly etched, and a wiring pattern similar to the masking material used is formed. Further, the base metal layer 12 below the conductive metal layer 20 is also etched considerably, but the base metal layer 12 is not completely removed in the conductive metal etching step.

As described above, after the conductive metal is selectively etched mainly using the masking material 22 made of a photosensitive resin, the masking material 22 made of the photosensitive resin is used for alkali such as sodium hydroxide or potassium hydroxide. It can be removed by treatment with a cleaning solution such as an aqueous solution containing, specifically, an aqueous solution containing NaOH + NaCO ₃ or the like. The cross-sectional shape of the wiring pattern from which the masking material has been removed as described above is, for example, as shown in FIG.

In the present invention, the conductive metal layer is mainly removed along the pattern which is a masking material as described above, and then dissolved and removed by the base metal etching step which selectively etches the base metal layer. Although a pattern is formed, a pickling process (micro etching process) can also be provided before this base metal etching process. That is, after the conductive metal layer is selectively etched mainly by the conductive metal etching process as described above, the pattern made of the photosensitive resin used as a masking material in the conductive metal etching process is a conductive metal layer. After passing through the etching step, it is removed by, for example, alkali cleaning, but an oxide film may be formed on the surface of the conductive metal layer or the surface of the base metal layer by contact with the alkali cleaning liquid. In addition, the conductive metal layer (Cu) surface (the top of the wiring pattern) that was in contact with the masking material made of a photosensitive resin does not have a history of contact with the etching material. The activity may be different when compared. Therefore, by performing pickling (microetching) after the conductive metal etching step to make the wiring pattern surface uniform, highly accurate etching can be performed in a later step.

  However, in this pickling process, if the contact time with the etching solution is long, the amount of elution of copper or copper alloy forming the wiring pattern will increase, and the wiring pattern itself will be thinned. In this pickling process, the contact time between the etching solution and the wiring pattern is usually about 2 to 60 seconds. The cross-sectional shape of the wiring pattern after the first pickling process as described above is, for example, as shown in FIG.

  After conducting the conductive metal etching process as described above, or after further passing through the pickling process as described above (after performing the first microetching), if necessary, the base metal etching process is followed mainly by the substrate metal etching process. The metal layer is dissolved and removed, and the remaining base metal is passivated.

  As described above, the base metal layer includes a metal such as copper, nickel, chromium, molybdenum, tungsten, silicon, palladium, titanium, vanadium, iron, cobalt, manganese, aluminum, zinc, tin, and tantalum, or these metals. The base metal layer is formed of an alloy or the like, and the metal forming the base metal layer is selectively eluted by using an etching solution corresponding to the forming metal, and further an insulating film The base metal layer forming metal slightly remaining on the surface is passivated.

  For example, when the base metal layer to be subjected to this base metal etching step is formed using nickel and chromium, the first treatment such as sulfuric acid / hydrochloric acid mixed liquid is performed on nickel. The solution (first treatment solution capable of dissolving Ni) can be dissolved and removed. For chromium, the second treatment solution (for example, potassium permanganate + KOH aqueous solution) can be used. Possible second treatment liquid).

  In the present invention, examples of the first treatment solution capable of dissolving Ni include a sulfuric acid / hydrochloric acid mixed solution having a concentration of about 5 to 15% by weight and a mixed solution of potassium persulfate and sulfuric acid. it can.

  By processing using this 1st process liquid, metals, such as nickel, are mainly melt | dissolved and removed among the metals which form a base metal layer. In the treatment using the first treatment liquid, the treatment temperature is usually 30 to 55 ° C., and the treatment time is usually 5 to 40 seconds.

By this treatment, for example, as shown in FIG. 2D, the base metal remaining in a protruding manner on the side surface of the wiring pattern and / or the base metal remaining between the wirings are dissolved and removed. As a result, the distance between the base metal layers constituting the adjacent wiring pattern becomes a value close to a planned value (design value). That is, although the interval between the base metal layers forming the wiring pattern differs depending on the design width of the wiring pitch to be formed, for example, when the wiring pitch is 30 μm (designed line width 15 μm, space width 15 μm) When the shortest distance between metals is measured by an electron micrograph (SEM photograph), it is often within a range of 5 to 18 μm. The actually measured shortest interval is 33% to 120% with respect to the design value. By setting the conditions more suitably, the shortest interval between the base metals is within the range of 10 to 16 μm, that is, to the design value. On the other hand, it can be in the range of 66.7 to 106.7%. For example, when the wiring pitch is 100 μm (designed line width 50 μm, space width 50 μm), the actually measured wiring pattern width can be 10 to 120% of the design value.

  In the treatment using the first treatment liquid, the base metal remaining in the protruding shape is dissolved and removed, as shown in FIG. 2E, a wiring pattern formed by the base metal layer of the wiring pattern. The distance (SA) from the wiring pattern forming continuous line to the tip of the protruding portion protruding in the width direction from the forming continuous line is 0 to 6 μm (0 to 40% of the design space width), preferably 0 to 5 μm, more preferably Means to dissolve so as to be 0 to 3 μm, most preferably 0 to 2 μm. Therefore, in the present invention, the distance from the wiring pattern forming continuous line to the tip is within the above range and is regarded as forming the wiring pattern forming continuous line and is not called a protrusion.

  The wiring pattern formed in the present invention is formed with a plating layer on the surface thereof in order to prevent oxidation in later steps and to form an alloy layer at the time of bonding such as an IC chip. When the is formed, it is desirable to secure at least 5 μm as the distance between the narrowest portions from the plating layer surface in the adjacent wiring pattern (shortest distance between the wiring patterns).

Thus, after processing using the 1st processing liquid, it processes using the 2nd processing liquid, but before processing using this 2nd processing liquid, it can give to a micro etching process.
In the present invention, when microetching is performed, as a microetching solution that can be used, for example, an etching solution used for etching Cu that is a conductive metal such as HCl or H ₂ SO ₄ is used. Furthermore, potassium persulfate (K ₂ S ₂ O ₈ ), sodium persulfate (Na ₂ S ₂ O ₈ ), sulfuric acid + H ₂ O _{2 and the} like can be used. In particular, in the present invention, it is preferable to use potassium persulfate (K ₂ S ₂ O ₈ ), sodium persulfate (Na ₂ S ₂ O ₈ ), or sulfuric acid + H ₂ O ₂ as the microetching solution.

  By microetching in this way, as shown in FIG. 2 (f), Cu, which is a conductive metal forming a wiring pattern, is selectively etched, but Ni, Cr, which are base metals, are selectively etched. Not very etched. In this microetching process, the conductive metal layer (Cu layer) 20 that mainly forms the wiring pattern is etched so as to slightly recede from the periphery of the wiring pattern toward the center, whereas the wiring pattern The base metal layer 12 that forms the layer is relatively difficult to be etched. Therefore, the wiring pattern formed through the microetching process is based on the lower end of the conductive metal layer of the wiring pattern formed from the conductive metal layer 20 and the wiring pattern formed from the base metal layer 12. A clear step is formed between the upper end portions of the metal layers. That is, by this microetching process, the portion formed of the conductive metal (Cu) of the wiring pattern recedes toward the central portion of the cross section of the wiring pattern by microetching, but the base metal layer of the wiring pattern is Since this microetching is difficult to dissolve, the shape of the wiring pattern formed by the base metal layer is maintained. Therefore, the wiring pattern formed through this microetching process has a shape in which an overhanging portion of the base metal layer is formed around the wiring pattern made of the conductive metal layer.

As shown in FIG. 2 (g), the microetching process is provided as described above in the middle of the base metal layer etching process using the first processing liquid and the second processing liquid. The width W1 of the upper end portion of the base metal layer and the width W2 of the lower end portion of the conductive metal layer 20 are clearly different, and the difference W3 (2 × (W3 / 2)) of W1−W2 is usually 0. .05-2.0μ
m, preferably in the range of 0.2 to 1.0 μm.

  Therefore, the microetching process is performed as described above while the base metal layer is being processed using the second processing liquid having a composition different from the processing process using the first processing liquid. In the obtained wiring pattern, a wiring pattern having a form in which a band-shaped protruding portion made of the base metal layer 12 having a width of W3 × 1/2 is formed around the wiring pattern made of the conductive metal layer 20 made of Cu or the like. It is done. The protrusion can be prevented from migrating by being treated with the second treatment liquid.

  Note that this microetching process is an optional process, and unless this microetching process is performed, the band-shaped protruding portion made of the base metal layer 12 as shown in FIG. Not formed.

After performing microetching as necessary as described above, it is processed using the second processing liquid.
The 2nd processing liquid used here is a processing liquid which can passivate this residual Cr, when Cr contained in a base metal layer is dissolved and Cr remains.

  That is, by processing using the first processing liquid as described above (and by performing microetching as necessary), Ni forming the base metal layer 12 is almost dissolved and removed, but the base metal layer Cr, which is the metal that forms 12, still remains on the insulating film 11. If such Cr remains between the wiring patterns, the insulation resistance value between the wiring patterns is not stable, so the Cr contained in the base metal layer 12 on the insulating film 11 is dissolved or removed, or the residual A second treating agent containing a component capable of passivating Cr is used.

As the second treating agent used here, Cr contained in the base metal layer can be dissolved and removed, and even when there is Cr remaining on the surface of the insulating film, this residual Cr is passivated. It is a processing liquid that can be used. Examples of such second treatment liquid include potassium permanganate / KOH aqueous solution and sodium permanganate + NaOH aqueous solution. In the present invention, when potassium permanganate + KOH aqueous solution is used as the second treatment liquid, the concentration of potassium permanganate is usually 10 to 60 g / liter, preferably 25 to 55 g / liter, and the KOH concentration Is preferably 10 to 30 g / liter. In the present invention, in the treatment using the second treatment liquid as described above, the treatment temperature is usually 40 to 70 ° C., and the treatment time is usually 10 to 60 seconds.

  By performing the treatment using the second treatment liquid in this way, most of the Cr forming the base metal layer 12 is dissolved and removed as shown in FIG. Further, even if a slight amount of Cr remains on the insulating film 11, this Cr can be passivated. That is, by processing using this second processing liquid, most of the Cr remaining as the base metal layer 12 on the surface of the insulating film 11 is dissolved, and the surface of the insulating film is probably several tens of millimeters thick. The remaining Cr can be oxidized and passivated.

Furthermore, by suitably using this second treatment liquid, the surface of the insulating film 11 can be chemically polished with this second treatment liquid as shown in FIG. 2 (j). Accordingly, the base metal layer 12 can be removed by suitably using the second treatment liquid, and the second treatment liquid is usually 1-100 nm, preferably from the surface of the insulating film 11. The insulating film 11 can be cut (dissolved and removed) at a depth of 5 to 50 nm. By using the second treatment liquid as described above, Cr remaining on the surface layer of the insulating film 11 can be removed together with the surface layer of the insulating film. Therefore, when this second treatment liquid is suitably used, the thickness of the insulating film 11 where the wiring pattern is not formed is 1 to 100 nm than the thickness of the insulating film where the wiring pattern is formed, The thickness is preferably 2 to 50 nm. Note that the base metal layer 12 and the insulating film 11 in the wiring pattern portion are protected from the second treatment liquid by the conductive metal layer 20.

  The wiring pattern of the printed wiring board obtained in this way is, as shown in FIG. 2 (j), a wiring pattern (conductive metal layer) made of the conductive metal layer 20 when microetching is not performed. The width of the lower end portion and the upper end portion of the base metal layer 12 are formed with the same or substantially the same width in the cross section, but the insulating film 11 (polyimide film) in the portion where the wiring pattern is not formed The surface is usually cut to a depth in the range of 1 to 100 nm, preferably 2 to 50 nm, and the portion where the wiring pattern is formed has a height of 1 to 100 nm, preferably 2 to 50 nm. A base-like base 17 having a trapezoidal cross section is formed.

  In addition, after processing using the second processing liquid as described above, generally, independent Ni is not confirmed on the insulating film between the wiring patterns, but Cr may remain slightly. However, such Cr is passivated, and the insulation between the wiring patterns is not impaired by such passivated Cr.

  After forming a wiring pattern using various etching agents in a plurality of etching processes as described above, this printed wiring board is washed with water, but it is used when forming a wiring pattern on the surface of the printed wiring board. The metal derived from the etched etching solution remains.

In particular, as an etchant used for etching a base metal layer, etching containing an oxidizing inorganic compound such as potassium permanganate is highly useful, but such an oxidizing inorganic compound. When an etching solution containing is used, a metal derived from such an etching solution remains on the surface of the printed wiring board. That is, after completion of the etching process, the printed wiring board is subjected to a water washing process, but the metal derived from the etching solution cannot be completely removed and remains on the surface of the printed wiring board only by such a normal water washing process after the etching process. This may cause contamination of a processing solution used in a subsequent process, and may cause a decrease in reliability of the printed wiring board, such as migration easily due to such residual metal. Here, the metal derived from the etchant is a metal that forms an oxidizable inorganic compound used in the last etching process, specifically, manganese or the like, and these metals are metal compounds such as oxides. Sometimes it is formed.

In this invention, after forming a wiring pattern as mentioned above, the insulating film in which this wiring pattern was formed is made to contact with the reducing aqueous solution containing a reducing substance.
Examples of the reducing substance used herein include organic acids having reducibility. Examples of such organic acids having reducibility include oxalic acid, citric acid, ascorbic acid, and organic carboxylic acid. Can be mentioned. These organic acids having reducibility can be used alone or in combination. These organic acids may form a salt.

  Such an organic acid having reducibility is used by dissolving in water at a concentration that does not affect the formed wiring pattern and can remove the metal derived from the remaining etching solution, and is usually 2-10. It is used by dissolving in water at a concentration of 3% by weight, preferably 3 to 5% by weight.

There is no particular limitation on the contact method between the reducing aqueous solution containing an organic acid having such a reducing property and the wiring pattern, but a method in which the reducing treatment solution uniformly contacts the wiring pattern may be adopted. Preferably, various methods such as, for example, a method of immersing the insulating film in which the wiring pattern is formed in the processing liquid, a method of spraying the processing liquid on the insulating film in which the wiring pattern is formed, and the like can be adopted. These methods may be combined.

  Such reducing treatment liquid is usually adjusted to a temperature in the range of 25 to 60 ° C., preferably 30 to 50 ° C., and the contact time with the reducing treatment liquid adjusted to such a temperature is Usually, it is 2 to 150 seconds, preferably 10 to 60 seconds. Thus, the metal derived from the etching solution remaining on the wiring pattern and the insulating film surface is efficiently removed by the contact with the reducing treatment solution.

  Thus, the wiring substrate (insulating film and the wiring pattern formed on the surface) that has been contact-treated with the reducing treatment liquid can be processed as it is in the next step, but is processed in the next step after being washed with water. It is preferable.

  In this water washing step, most of the metal derived from the etching solution remaining on the surface by contact with the reducing treatment solution as described above is removed, so that the time required for this water washing is reduced to the normal water washing step. The time required can be shortened. In the present invention, the water washing after the treatment with the reducing treatment solution is usually for 2 to 60 seconds, preferably 15 to 40 seconds, as compared with the case where the treatment with the aqueous solution containing the reducing substance is not performed. The water washing time can be shortened to about 1/2 to 1/30.

In this way, in the present invention, after performing the etching process in a plurality of steps using etching liquids having different compositions, the print is processed with an aqueous solution containing a reducing substance, and further preferably washed with water. residual amount of the metal derived from the etching solution at the surface of the wiring substrate, 0.05 [mu] g / cm ² or less, preferably be in the range of 0.000002~0.03μg / cm ^2. That is, the oxidizing inorganic compound used mainly for etching the base metal layer has a tendency to partially remain on the substrate surface, and such an oxidizing inorganic compound can be completely removed only by washing with water. It cannot be removed.

In the present invention, the remaining amount of the metal derived from the etching solution on the surface of the printed wiring board is obtained by cutting out 1 piece of one wiring pattern formed from a long film carrier tape for mounting electronic components. (For example, a 35 mm wide tape is cut into a length of 47.5 mm, which is 10 perforations on which one wiring pattern is formed), and used as a sample. 2) This sample is treated with pure water (100 cc) as a solution. ) And boiled at 100 ° C. for 5 hours to extract Mn contained in the sample into hot water. 3) The amount of Mn eluted in the hot water was determined by ICP-MS (Inductively Coupled Plasma Mass Spectrometer; ICP The amount of Mn extracted by analytical measurement was obtained by dividing the total amount of Mn obtained by the total area (total area of both surfaces) of the cut sample.

After contact with an aqueous solution containing a reducing substance as in the present invention, the remaining amount of the metal derived from the etching solution on the surface of the printed wiring board is 0.05 μg / cm ² or less by washing with water, and further reducing properties. By suitably adjusting the conditions of contact with the solution containing the substance and washing with water, the amount can be in the range of 0.000002 to 0.03 μg / cm ² . Thus, the remaining amount of the metal derived from the etching solution is in an amount that cannot be achieved in a short time by ordinary water washing.

The wiring pattern thus formed on the printed wiring board is covered with a resin protective layer so that the terminal portion is exposed, but before forming the resin protective layer, at least the base metal layer of the formed wiring pattern is covered. It is also possible to carry out concealment plating. That is, after forming the wiring pattern, the resin is treated with an aqueous solution containing a reducing substance so as to remove the metal derived from the etching solution remaining on the formed wiring pattern and the exposed insulating film, and further washed with water, Before forming the coating layer, the plating layer can be formed so as to conceal the exposed portion of the base metal layer at the lower end of the wiring pattern.

The concealing plating layer formed here is at least a base metal layer at the lower end of the wiring pattern, and the concealing plating layer can also be formed on the entire wiring pattern. Examples of the concealment plating layer thus formed include a tin plating layer, a gold plating layer, a nickel-gold plating layer, a solder plating layer, a lead-free solder plating layer, a Pd plating layer, a Ni plating layer, a Zn plating layer, and There are Cr plating layers, etc., and these plating layers may be a single layer or a composite plating layer in which a plurality of plating layers are laminated. In the present invention, in particular, a tin plating layer, a gold plating layer, a nickel plating layer, nickel -Gold plated layer is preferred. In addition, this concealing plating may be formed on the exposed terminal portion after forming the resin protective layer so as to cover the terminal portion of the formed wiring pattern.

  The thickness of such a concealing plating layer can be appropriately selected depending on the type of plating, but is usually set to a thickness in the range of 0.005 to 5.0 μm, preferably 0.005 to 3.0 μm. Is done. Alternatively, after concealing plating is performed on the entire surface and the terminal portion is exposed to form the resin protective layer, the portion exposed from the resin protective layer may be further plated using the same metal for the terminal portion. Also by forming the concealing plating layer having such a thickness, it is possible to prevent migration from the base metal layer forming the wiring pattern.

Such a concealing plating layer can be formed by an electrolytic plating method or an electroless plating method.
By performing the concealing plating process on the wiring pattern in this way, the surface of the passivated base metal layer on the insulating substrate side of the wiring pattern is concealed by the concealing plating layer, and even if a potential difference occurs between different metals, Since the insulation resistance between the wiring patterns is sufficiently high, the occurrence of migration from the base metal layer can be effectively prevented. This concealing plating is mainly intended for the occurrence of migration from the base metal layer, but is not limited to such concealment of the base metal layer, for example, the plating process of the subsequent terminal portion It may be for the purpose of preventing the occurrence of pitting corrosion.

  After performing concealment plating as necessary in this manner, a resin protective layer is formed so as to cover the wiring pattern and the insulating film in the portion where the wiring pattern is formed, leaving the terminal portion of the wiring pattern. This resin protective layer can be formed by, for example, applying a solder resist ink to a desired portion by using a screen printing technique, and further applying a resin film having an adhesive layer to a desired shape in advance. It can also be formed by sticking this shaped resin film.

  After forming a resin protective layer such as a solder resist layer in this way, a plating layer is formed on the surface of the wiring pattern exposed from the resin protective layer. That is, the terminal portion exposed from the solder resist layer or the resin protective layer is plated. This plating process electrically connects the bump electrodes formed on the electronic component and the terminals of the printed wiring board when the electronic component is mounted on the printed wiring board. When the mounted printed wiring board (semiconductor device) is incorporated into an electronic device, the printed wiring board is for establishing an electrical connection between the printed wiring board and another member.

Examples of the plating layer formed in this manner include a tin plating layer, a gold plating layer, a silver plating layer, a nickel-gold plating layer, a solder plating layer, a lead-free solder plating layer, a palladium plating layer, a nickel plating layer, and a zinc plating layer. And a chromium plating layer. This plating layer may be a single layer or a composite plating layer in which a plurality of plating layers are laminated. The metal plating layer as described above may be a pure metal layer made of the above metal or may have a diffusion layer in which another metal is diffused. In the case of forming a diffusion layer, a plating layer made of a metal forming the diffusion layer is formed on the surface of the metal (or metal plating layer) to be diffused. A diffusion layer diffused with metal is formed.

  In addition, such a plating layer is usually a plating layer made of the same metal in a single printed wiring board, but this metal plating layer is not necessarily formed from the same metal in a single printed wiring board. It is not necessary that the type of metal forming the plating layer differs depending on the terminal.

The plating layer as described above can be formed by a normal plating method such as an electroplating method or an electroless plating method.
The average thickness of such a plating layer varies depending on the type of plating layer to be formed, but is usually in the range of 5 to 12 μm. When the wiring pattern has a plurality of plating layers, the average thickness of the plating layer is the total thickness of the plating layers formed in the wiring pattern.

  Examples of the cross-sectional shape of the wiring pattern formed as described above are shown in (1) to (4) of FIG. In FIG. 3, number 11 is an insulating film, number 12 is a base metal layer, number 20 is a conductive metal layer, and number 16 is a plating layer.

  An electronic component such as an IC chip is mounted by electrically connecting the terminal of the printed wiring board formed as described above and an electrode such as a bump electrode formed on the electronic component. A semiconductor device can be manufactured by resin-sealing the electronic component and its periphery.

The printed wiring board and the semiconductor device of the present invention are formed because the metal derived from the etching solution used in a plurality of etching processes is removed by processing with an aqueous solution containing a reducing substance. wiring pattern and the residual amount of the metal derived from the etching solution between the wiring patterns 0.05 [mu] g / cm ² or less, more preferably can be a very small amount and 0.000002~0.003μg / cm ^2, thus, Migration due to the remaining metal is less likely to occur, and the plating solution used in the subsequent process is not contaminated by the remaining metal, so that a highly reliable printed wiring board can be obtained.

  As described above, the printed wiring board or the semiconductor device of the present invention has a remarkably small amount of the metal derived from the etching solution on the wiring pattern and the insulating film. Therefore, the printed wiring board or the semiconductor device of the present invention can be obtained by migration or the like. The electrical resistance value between the wiring patterns hardly fluctuates. That is, the printed wiring board and the semiconductor device of the present invention have a remarkably small amount of residual metal derived from the etching solution, are less prone to migration due to such residual metal, and have an insulation resistance after a voltage is continuously applied for a long time. No substantial variation is observed between the insulation resistance before the voltage is applied and the printed wiring board has very high reliability.

  The printed wiring board of the present invention has a wiring pattern (or lead) width of 30 μm or less, preferably 25 to 5 μm, and a pitch width of 50 μm or less, preferably 40 to 20 μm. Suitable for printed wiring boards having a width.

Such a printed wiring board of the present invention includes a printed circuit board (PWB), FPC (Flexible Printed Circuit), TAB (Tape Automated Bonding) tape, COF (Chip On Film), CSP (Chip Size Package), BGA ( Ball Grid Array) and μ-BGA (μ-Ball Grid Array).

  In the printed wiring board of the present invention described above, a polyimide film is used as an insulating film, and the printed wiring board in which a wiring pattern is formed on the surface of the insulating film has been mainly described. An electronic component is mounted on the wiring pattern, and the periphery of the mounted electronic component is formed by sealing with a resin. This semiconductor device also has very high reliability.

〔Example〕
Next, the method for producing a printed wiring board of the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto. The insulation resistance values described below are all measured values at room temperature outside the thermostatic chamber.

One surface of a polyimide film (Ube Industries, Ltd., Upilex S) with a width of 35 mm and an average thickness of 38 μm was roughened by reverse sputtering, and then an average thickness was obtained by sputtering a nickel-chromium alloy under the following conditions: A chromium / nickel alloy layer having a thickness of 40 nm was formed as a base metal layer. That is, a 38 μm-thick polyimide film was treated at 100 ° C. under the condition of 3 × 10 ⁻⁵ Pa for 10 minutes, and then the inside of the apparatus was degassed to a pressure of 100 ° C. × 0.5 Pa to perform chromium-nickel alloy sputtering Thus, a base metal layer was formed.

On the base metal layer formed as described above, copper was deposited by electroplating to form an electrolytic copper layer (conductive metal layer) having a thickness of 8 μm.
The surface of the electrolytic copper layer thus formed is coated with a photosensitive resin, exposed and developed to form a comb electrode pattern so that the wiring pitch is 30 μm (line width: 15 μm, space width: 15 μm), Using this pattern as a masking material, the electrolytic copper layer was HCl; 100 g /
A wiring pattern was manufactured by etching for 30 seconds using a 12% copper chloride etchant containing liter.

The masking material formed with the photosensitive resin on the obtained wiring pattern was removed by treatment with NaOH + NaCO ₃ solution at 40 ° C. for 30 seconds.
Next, a K ₂ S ₂ O ₈ + H ₂ SO ₄ solution was used as a pickling solution, followed by treatment at 30 ° C. for 10 seconds, and the electrolytic copper layer and the base metal layer (Ni—Cr alloy) were pickled.

Next, using a solution containing 17 g / liter HCl and 17 g / liter H ₂ SO ₄ as the first treatment liquid, the film carrier tape was treated at 50 ° C. for 30 seconds to obtain a Ni—Cr alloy. The resulting base metal layer Ni was dissolved.

Furthermore, using a H ₂ S ₂ O ₈ + H ₂ SO ₄ solution as a micro-etching solution, the Cu conductor is adjusted so that the processing depth becomes 0.3 μm from the edge of the wiring pattern to the inside. Selectively dissolved (Cu conductor receding).

  Further, using 40 g / liter potassium permanganate + 20 g / liter KOH solution as the second treatment liquid, the treatment was performed at 65 ° C. for 30 seconds to dissolve Cr contained in the base metal layer. This second treatment solution was able to dissolve and remove chromium in the base metal layer and to oxidize and slightly pass the remaining chromium.

Next, an oxalic acid aqueous solution in which 40 g / liter of oxalic acid dihydrate ((COOH) -2H ₂ O) is dissolved is used to remove Mn remaining on the insulating film and the pattern. The substrate was washed at 40 ° C. for 1 minute to dissolve and remove residual Mn. Thereafter, washing was performed with pure water at 23 ° C. for 15 seconds.

Thus, the Mn remaining on the substrate when washed with an oxalic acid aqueous solution at 40 ° C. for 1 minute was 0.0003 μg / cm ² . On the other hand, when the cleaning with the oxalic acid aqueous solution was not performed (Reference Example 1), it was 0.14 μg / cm ^{2. When} the oxalic acid aqueous solution cleaning was not performed, a considerable amount of Mn was deposited on the substrate. There is a possibility that the printed wiring board is formed while the Mn remains without being removed in a subsequent process, which may cause deterioration of the quality of the printed wiring board. Further, the remaining Mn may contaminate a chemical solution used in a later process and cause a decrease in the appearance or quality of the printed wiring board.

After the wiring pattern was formed as described above, electroless tin plating was applied to the formed wiring pattern with a thickness of 0.01 μm.
Furthermore, after concealing the wiring pattern with the tin plating layer as described above, a solder resist layer was formed so as to expose the connection terminals and the external connection terminals.

  On the other hand, the internal connection terminal and the external connection terminal exposed from the solder resist layer are subjected to Sn plating with a thickness of 0.5 μm and heated to obtain a predetermined pure Sn layer (total Sn plating thickness: 0.51 μm, pure Sn layer thickness). 0.25 μm).

The cross-sectional shape of the wiring pattern thus formed had a shape approximated to FIG.
The printed wiring board on which the comb-shaped electrode was formed in this manner was subjected to a continuity test (HHBT) for 1000 hours by applying a voltage of 40 V under the condition of 85 ° C. and 85% RH. This continuity test is an accelerated test, and is a test in which the time until a short circuit occurs (for example, the time until the insulation resistance value becomes less than 1 × 10 ⁸ Ω) is set to about 1000 hours. At that time, those having an insulation resistance value of less than 1 × 10 ⁸ Ω cannot be used as a general substrate. Also,
When the insulation resistance value after 1000 hours is less than 1 × 10 ¹⁴ Ω, there is a possibility of causing a problem in practical use.

In the printed wiring board manufactured in Example 1, the insulation resistance before the insulation reliability test is 6 × 10 ¹⁴ Ω, and the insulation resistance measured after the insulation reliability test is 6 × 10 ¹⁴ Ω. No substantial difference in insulation resistance due to the application of voltage was observed.

On the other hand, the insulation resistance measured after the insulation reliability test of the sample not subjected to the oxalic acid treatment (Reference Example 1) is 1.0 × 10 ¹⁴ Ω, which is obtained by performing the treatment using oxalic acid. The insulation reliability of the printed wiring board was improved.

  The results are shown in Table 1.

One surface of a polyimide film (Ube Industries, Ltd., Upilex S) with a width of 35 mm and an average thickness of 38 μm was roughened by reverse sputtering, and then an average thickness was obtained by sputtering a nickel-chromium alloy under the following conditions: A chromium / nickel alloy layer having a thickness of 40 nm was formed as a base metal layer. That is, a 38 μm-thick polyimide film was treated at 100 ° C. and 3 × 10 ⁻⁵ Pa for 10 minutes, and then the pressure inside the apparatus was set to 100 ° C. × 0.5 Pa to perform chromium-nickel alloy sputtering to form a base metal layer. Formed.

On the base metal layer formed as described above, copper was deposited by electroplating to form an electrolytic copper layer (electroplated copper layer) having a thickness of 8 μm.
A photosensitive resin is applied to the surface of the electrolytic copper layer thus formed, exposed and developed to form a comb electrode pattern so that the wiring pitch is 30 μm (line width: 15 μm, space width: 15 μm), Using this pattern as a masking material, the electrolytic copper layer was etched for 30 seconds using a 12% cupric chloride etchant containing HCl: 100 g / liter, and the wiring pattern was similar to the pattern formed from a photosensitive resin. Manufactured.

The masking material formed with the photosensitive resin on the obtained wiring pattern was removed by treatment with NaOH + NaCO ₃ solution at 40 ° C. for 30 seconds.
Then as the first treatment _{liquid, K 2 S 2 O 8 +} H 2 SO 4 solution was treated 30 ° C. × 10 seconds, and pickled copper and the base metal layer (Ni-Cr alloy).

Next, using a KOH etching solution having a concentration of 40 g / liter potassium permanganate + 20 g / liter as the second treatment solution, the Ni—Cr alloy overhang was passivated over 40 ° C. for 1 minute, and The chromium that remained slightly between the lines was eluted as much as possible, and the chromium that could not be removed was passivated as chromium oxide.

Next, an oxalic acid aqueous solution in which 40 g / liter of oxalic acid dihydrate ((COOH) -2H ₂ O) is dissolved is used to remove Mn remaining on the film and pattern of the circuit board. The substrate was used and washed at 40 ° C. for 1 minute to dissolve and remove the remaining Mn. Thereafter, cleaning was performed for 15 seconds at 23 ° C. pure water.

Thus, Mn adhering to the substrate when washed with an oxalic acid aqueous solution at 40 ° C. for 1 minute was 0.00056 μg / cm ² . On the other hand, when the washing with the oxalic acid aqueous solution was not performed (Reference Example 2), the amount of residual Mn was 0.11 μg / cm ² .

Furthermore, Sn plating having a thickness of 0.5 μm was performed and heated to form a predetermined pure Sn layer.
The cross-sectional shape of the wiring pattern thus formed had a shape approximated to FIG.

The printed wiring board on which the comb-shaped electrode was formed in this manner was subjected to a continuity test (HHBT) for 1000 hours by applying a voltage of 40 V under the condition of 85 ° C. and 85% RH. The insulation resistance of the printed wiring board before the insulation reliability test was 5 × 10 ¹⁴ Ω, and the insulation resistance measured after the insulation reliability test was 5 × 10 ¹⁴ Ω. A voltage was applied between the two. No substantial difference in insulation resistance was observed.

On the other hand, the insulation resistance measured after the insulation reliability test of the sample not subjected to the oxalic acid treatment (Reference Example 2) is 3.5 × 10 ¹⁴ Ω, and by performing the treatment using oxalic acid, The insulation reliability of the obtained printed wiring board was improved.

  The results are shown in Table 1.

One surface of a polyimide film (Ube Industries, Ltd., Upilex S) with a width of 35 mm and an average thickness of 38 μm was roughened by reverse sputtering, and then an average thickness was obtained by sputtering a nickel-chromium alloy under the following conditions: A chromium / nickel alloy layer having a thickness of 40 nm was formed as a base metal layer. That is, after processing a 38 μm-thick polyimide film at 100 ° C. and 3 × 10 ⁻⁵ Pa for 10 minutes, the inside of the apparatus is adjusted to 100 ° C. × 0.5 Pa and sputtering of a chromium-nickel alloy is performed to form a base metal. A layer was formed.

On the base metal layer formed as described above, copper was deposited by electroplating to form an electrolytic copper layer (electroplated copper layer) having a thickness of 8 μm.
The surface of the electrolytic copper layer thus formed is coated with a photosensitive resin, exposed and developed to form a comb electrode pattern so that the wiring pitch is 30 μm (line width: 15 μm, space width: 15 μm), Using this pattern as a masking material, the electrolytic copper layer was HCl; 100 g /
A wiring pattern similar to the pattern formed of the photosensitive resin was manufactured by etching for 30 seconds using a 12% concentration cupric chloride etchant containing liter.

The masking material formed of the photosensitive resin on the obtained wiring pattern was removed by treating with NaOH + NaCO ₃ solution at 40 ° C. for 30 seconds.
Next, it was treated with K ₂ S ₂ O ₈ + H ₂ SO ₄ solution as a pickling solution at 30 ° C. for 10 seconds, and copper and a base metal layer (Ni
-Cr alloy) was pickled.

Next, using a 15% HCl + 15% H ₂ SO ₄ solution, which is a first treatment solution capable of dissolving Ni, dissolves Ni in the Ni—Cr alloy overhang 26 over 50 ° C. × 30 seconds. The polyimide as an insulating film was exposed between the wiring patterns.

Furthermore, as a second treatment solution capable of dissolving Cr and dissolving polyimide, 40 g / liter potassium permanganate + 20 g / liter KOH solution is used to treat the metal between the wiring patterns with the polyimide film below it. Along with the 50 nm thickness, dissolution was removed.

Next, an oxalic acid aqueous solution in which 40 g / liter of oxalic acid dihydrate ((COOH) -2H ₂ O) is dissolved is used to remove Mn remaining on the film and pattern of the circuit board. The substrate was used and washed at 40 ° C. for 1 minute to dissolve and remove the remaining Mn. Thereafter, washing was performed with pure water at 23 ° C. for 15 seconds.

Thus, the Mn remaining on the substrate when washed with an oxalic acid aqueous solution at 40 ° C. for 1 minute was 0.00028 μg / cm ² . On the other hand, when the washing with the oxalic acid aqueous solution was not performed (Reference Example 3), the remaining amount of Mn was 0.056 μg / cm ² .

  Further, a solder resist layer is formed so as to expose the internal connection terminals and external connection terminals, and the other exposed internal connection terminals and external connection terminals are plated with 0.5 μm of Sn and heated to a predetermined pure level. An Sn layer was formed.

The cross-sectional shape of the wiring pattern formed in this way had a shape approximated to FIG.
The printed wiring board on which the comb-shaped electrode was formed in this manner was subjected to a continuity test (HHBT) for 1000 hours by applying a voltage of 40 V under the condition of 85 ° C. and 85% RH. The insulation resistance before the insulation reliability test of the printed printed circuit board was 7 × 10 ¹⁴ Ω, the insulation resistance measured after the insulation reliability test was 8 × 10 ¹⁴ Ω, and a voltage was applied between the two. There was no substantial difference in insulation resistance.

On the other hand, the insulation resistance measured after the insulation reliability test of the sample not subjected to the oxalic acid treatment (Reference Example 3) is 4.6 × 10 ¹⁴ Ω, which is obtained by performing the treatment using oxalic acid. The insulation reliability of the printed wiring board was improved.

  The results are shown in Table 1.

As described above, the printed wiring board of the present invention removes the metal derived from the etching solution by treating it with an aqueous solution containing a reducing substance, so that the residual amount of the etching liquid-derived metal on the surface of the printed wiring board is reduced. The occurrence of migration due to such residual metal is extremely small, and a highly reliable printed wiring board and semiconductor device can be obtained. Further, when the printed wiring board is manufactured, since the metal derived from the etching solution is removed, the processing solution in the subsequent process, and further, the apparatus is not contaminated by the metal derived from the etching solution, and it is efficient. A printed wiring board and a semiconductor device can be manufactured. Moreover, since the metal derived from the etching solution can be efficiently removed with the treatment liquid containing the reducing substance, the water washing step can be shortened, and the printing method can be efficiently performed by employing the manufacturing method of the present invention. A wiring board can be manufactured.

FIG. 1 is a process diagram showing an example of a process for producing a printed wiring board of the present invention. FIG. 2 is a view showing an example of a cross section of a wiring pattern or the like in each step of manufacturing the printed wiring board of the present invention. FIG. 3 is a diagram schematically showing an example of a cross section of a wiring pattern formed by the method of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Insulating film 12 ... Base metal layer 16 ... Plating layer 17 ... Substrate base 20 of a cross section ... Conductive metal layer 22 ... Masking material

Claims (11)

Dissolving mainly conductive metal of a base film having an insulating film, a base metal layer formed on at least one surface of the insulating film, and a conductive metal layer formed on the base metal layer In manufacturing a printed wiring board through a plurality of etching steps including a step of selectively etching a conductive metal in a conductive metal etching step and a base metal etching step mainly dissolving a base metal,
The conductive metal layer is selectively removed by etching, and the conductive metal layer is removed by contacting with the first treatment liquid that dissolves the Ni metal forming the base metal layer.
The base metal layer is brought into contact with a second processing liquid that has a different chemical composition than the first processing liquid and acts with high selectivity for Cr, which is a base metal layer forming metal, compared to the conductive metal. In addition to passivating Cr contained in the film, passivating Cr remaining on the insulating film, and forming a base metal layer remaining on the surface of the insulating film on which the wiring pattern is not formed Removing the passivated Cr together with the surface of the insulating film;
A method for producing a printed wiring board, comprising: bringing the insulating film on which the wiring pattern is formed into contact with a reducing aqueous solution containing a reducing organic acid or a salt thereof. Dissolving mainly conductive metal of a base film having an insulating film, a base metal layer formed on at least one surface of the insulating film, and a conductive metal layer formed on the base metal layer After conducting a plurality of etching steps including a conductive metal etching step and a base metal etching step for mainly dissolving the base metal, a wiring pattern is formed by selective etching,
Removing the Ni metal that forms the base metal layer in contact with the first treatment liquid,
Then, after contacting with a microetching solution that selectively dissolves the conductive metal,
The wiring pattern has a chemical composition different from that of the first treatment liquid, and is brought into contact with a second treatment liquid that acts with high selectivity on Cr, which is a base metal layer forming metal, rather than on a conductive metal. The base metal layer remaining on the surface layer of the insulating film that is not formed is formed and the passivated Cr is removed together with the surface of the insulating film,
2. The printed wiring board manufacturing method according to claim 1, wherein the insulating film on which the wiring pattern is formed is further brought into contact with a reducing aqueous solution containing a reducing organic acid or a salt thereof.   3. The method for manufacturing a printed wiring board according to claim 1, wherein the reducing substance contained in the reducing aqueous solution is a reducing organic acid or a salt thereof.   4. The printed wiring board according to claim 3, wherein the reducing organic acid is at least one organic acid selected from the group consisting of ascorbic acid, oxalic acid, citric acid and organic carboxylic acid. Manufacturing method. Metal manganese or manganese compounds remaining on the wiring board on which the wiring pattern is formed,
After the step of contacting with the first treatment liquid that dissolves Ni forming the base metal, it has a chemical composition different from that of the first treatment liquid and acts on Cr with higher selectivity than the conductive metal. The Cr remaining on the surface of the insulating film of the printed wiring board on which the wiring pattern is formed in contact with the second processing liquid is passivated and is contacted with the second processing liquid when removed together with the surface layer of the insulating film. 3. A metal or a metal compound derived from an oxidizing inorganic compound which is potassium permanganate and / or sodium permanganate remaining in a wiring board formed by the above method. Manufacturing method of printed wiring board.   3. The method for producing a printed wiring board according to claim 1, wherein the printed circuit board is washed with running water for 2 seconds or longer after contacting with the reducing aqueous solution. The method for producing a printed wiring board according to claim 1 or ² , wherein the residual amount of the metal derived from the etching solution in the formed printed wiring board is 0.05 µg / cm ² or less. 8. The printed wiring board according to claim 7, wherein a residual amount of the metal derived from the etching solution in the formed printed wiring board is in a range of 0.000002 to 0.03 [mu] g / cm < ² >. Method.   The printed wiring board manufacturing method according to claim 1 or 2, wherein the base metal layer contains nickel and chromium.   3. The method for manufacturing a printed wiring board according to claim 1, wherein the conductive metal layer is formed of copper or a copper alloy.   The method for manufacturing a printed wiring board according to claim 1 or 2, wherein the insulating film is a polyimide film.

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