JP2018115373A - Method of etching laminate, and method of manufacturing printed wiring board using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the above-mentioned problems in the semi-additive method in the production of a two-layer flexible wiring board, and selectively etch the base metal layer without dissolving copper in the etching of the base metal layer and the structure made of copper. Disclosed is a method for manufacturing a highly reliable substrate that is free from defects such as disconnection and short circuit by suppressing a decrease in the wiring width of the copper wiring. A base metal layer formed of an alloy containing one or more metals selected from Ni and Cr without using an adhesive on at least one surface of an insulating substrate, and a copper coating layer on the surface of the base metal layer A method for etching a formed laminate, wherein after the copper coating layer is removed by etching, the exposed base metal layer is contacted with a water-soluble organic solvent having an alcoholic hydroxyl group, and then permanganic acid A method for etching a laminate, characterized by performing etching with an acidic oxidizing agent containing a salt and removing it. [Selection] Figure 1

Description

The present invention relates to a method for etching a laminate, and further relates to a method for manufacturing a printed wiring board that is a material for an electronic component such as a TAB tape or a COF tape using the etching method.
In more detail, in copper wiring formation by the semi-additive method in the printed wiring board manufacturing method, by performing predetermined etching, the metal remains between the wirings without side etching of the copper layer in an inexpensive and simple process. The present invention relates to a method for manufacturing a printed wiring board capable of forming a pattern having sufficient insulation reliability even in a fine wiring processed product, and a printed wiring board obtained by the manufacturing method.

In general, a substrate used to fabricate a flexible wiring substrate is a three-layer flexible substrate in which a copper foil serving as a conductor layer is bonded onto an insulator film using an adhesive (for example, see Patent Document 1), It is roughly classified into a two-layer flexible substrate in which a copper coating layer that is a conductor layer is directly formed on an insulating film by a dry plating method or a wet plating method without using an adhesive.
With the recent increase in the density of electronic devices, a wiring board with a narrower wiring width has been demanded. In this case, in the manufacture of the three-layer flexible substrate, a subtractive method is used. Copper wiring formation is used. The manufacturing method is to form a wiring portion by etching a copper coating layer formed on an insulating film as a substrate with a ferric chloride solution or a cupric chloride solution containing hydrochloric acid according to a desired wiring pattern to form a wiring board. When manufacturing by etching the wiring part, the side surface of the wiring part is etched, so-called side etching occurs, so that the cross-sectional shape of the wiring part tends to become a trapezoid with a skirt spread. It was.

For this reason, in order to satisfy such a demand, instead of the conventional bonded copper foil (three-layer flexible substrate), a two-layer flexible substrate having a thin copper thickness is now becoming mainstream.
In order to produce a two-layer flexible substrate, an electrolytic copper plating method is usually employed as means for forming a copper coating layer having a uniform thickness on an insulator film. In order to perform electro copper plating, a thin metal layer is formed on an insulator film on which an electro copper plating film is applied to impart conductivity to the entire surface, and an electro copper plating process is performed thereon. It is general (see, for example, Patent Document 2). In order to obtain a thin metal layer on the insulator film, it is common to use a dry plating method such as a vacuum deposition method or an ion plating method.

In such circumstances, the adhesion between the insulator film and the copper layer is very weak because a brittle layer such as CuO or Cu ₂ O is formed at the interface, and the adhesion with the copper layer required for the printed wiring board. In order to maintain the strength, a base metal layer such as a Ni—Cr alloy is provided between the insulator film and the copper layer (see Patent Document 3).

  In recent flexible substrates, in order to cope with the narrower pitch of the wiring accompanying the further increase in the density of the wiring pattern, copper wiring formation by a semi-additive method is used in the production of the high-density wiring board. In the semi-additive method, a pattern resist is formed by photolithography on the copper film layer formed on the insulator film, and electro copper plating is applied. Finally, the resist is removed and the unnecessary copper film layer is removed by etching. Thus, a copper wiring is formed (hereinafter, this etching is referred to as flash etching).

  In this flash etching, for example, a sulfuric acid / hydrogen peroxide aqueous solution or the like is used as an etching solution. In order to maintain the adhesion strength even in the semi-additive method, a two-layer plating substrate in which a Ni—Cr alloy layer is provided as a base metal layer between an insulator film and a copper coating layer is often used. In this case, since the Ni—Cr alloy layer is difficult to dissolve in the sulfuric acid / hydrogen peroxide aqueous solution, only the copper coating layer is etched away after the flash etching step, and most of the underlying metal layer remains undissolved. Although there are prior arts (see Patent Documents 4 and 5) related to the removal process of the base metal layer and the etching solution, since the base metal layer is nickel, the Ni-Cr alloy layer having high corrosion resistance is removed. It is difficult to do.

As a method for removing the Ni—Cr alloy layer, for example, Patent Document 6 uses a combination of a commercially available nickel / chromium selective etching solution containing hydrochloric acid and sulfuric acid and an alkaline etching solution such as a potassium permanganate solution. There is a description that the etching residue of the Ni—Cr alloy is dissolved by the treatment.
In addition, when treated with a commercially available acidic etching solution containing hydrochloric acid and sulfuric acid, it is difficult to completely remove Cr, and it is necessary to use it together with an alkaline etching solution such as a potassium permanganate solution suitable for removing Cr. . Treatment with an alkaline etching solution such as a permanganic acid solution is effective for removing Cr. However, to use the etching solution, a processing facility dedicated to alkali is required, and the number of steps can be easily increased. It was difficult. Moreover, since it is a strong alkali solution, it is highly possible that the dissolved Cr will be in the form of toxic hexavalent chromium, so that it is necessary to pay sufficient attention and cost to the disposal of the waste liquid.

  Moreover, since an acidic etching liquid contains about 10-20 weight% hydrochloric acid, since it will dissolve copper as it is, since it must contain a fixed amount of the inhibitor which suppresses dissolution of copper, it is daily. It was necessary to manage the copper concentration and the inhibitor concentration.

  The inventors have so far been an inexpensive and simple process as a Ni-Cr selective etching solution in the subtractive method, and the etching residue of the Ni-Cr alloy can be removed by a method with little side etching on the copper wiring. A method using an acidic permanganic acid solution has been proposed (see Patent Document 7). By the way, the technique disclosed in Patent Document 7 is a technique for removing the etching residue of Ni—Cr alloy by etching of copper by a subtractive method, and even Ni—Cr alloy remaining without being etched by flash etching or the like. It is difficult to remove.

JP-A-6-132628 Japanese Patent Laid-Open No. 8-139448 JP-A-6-120630 JP 2003-258411 A JP 2006-294797 A JP 2007-201216 A JP 2010-13688 A

  However, unlike the removal of the Ni—Cr alloy, which is the remaining undissolved base metal layer in the subtractive method, in the semi-additive method, the base metal layer that is hardly etched after the flash etching must be removed. Even when an acidic permanganic acid solution effective for the selective removal of this Ni-Cr alloy is used, it takes some time to remove the underlying metal layer after the flash etching, and the etching time becomes longer. There is a risk of side etching of the copper wiring. Further, the undissolved residual metal layer component between the wirings is likely to occur, and it is difficult to manufacture a highly reliable substrate.

  In view of such a situation, the present invention solves the above-mentioned problems in the semi-additive method in the production of a two-layer flexible wiring board, and in the etching of a base metal layer and a structure composed of copper, without dissolving copper. An object of the present invention is to provide a highly reliable substrate manufacturing method free from defects such as disconnection and short circuit by selectively dissolving a base metal layer and suppressing a decrease in the wiring width of a copper wiring.

  In order to solve such problems, the present inventors have studied as an etching method for forming a fine wiring by a semi-additive method on a two-layer flexible substrate provided with a base metal layer. In order to remove, a step of treating with an acidic oxidant containing permanganate which has an effect of dissolving the base metal layer component while suppressing dissolution of copper, and a hydrophilic solvent prior to the treatment with the oxidant It has been found that there is an effect of removing the base metal layer component between the fine wirings quickly and without being undissolved by performing the pretreatment with the pretreatment liquid comprising the present invention, and the present invention has been completed.

  That is, according to a first aspect of the present invention, there is provided a base metal layer formed of an alloy containing at least one metal selected from nickel and chromium without using an adhesive on at least one surface of an insulating substrate, and the base metal A method for etching a laminate in which a copper coating layer is formed on a surface of a layer, wherein the exposed base metal layer after etching the copper coating layer is contacted with a water-soluble organic solvent having an alcoholic hydroxyl group A method for etching a laminate is characterized by performing etching with an acidic oxidizing agent containing a permanganate after the removal.

  According to a second aspect of the present invention, there is provided a method for etching a laminate, wherein a step of removing a manganese compound with a manganese residue removing solution is further added after the treatment step with an acidic oxidizing agent in the first aspect. .

  In the third invention of the present invention, the oxidizing agent in the first and second inventions is a solution containing 0.01 to 10% by weight of permanganate and 0.005 to 2% by weight of hydrochloric acid. This is a method for etching a laminated body.

  According to a fourth aspect of the present invention, the organic solvent in the first to third aspects is at least one alcohol selected from methyl alcohol, ethyl alcohol, n-propyl alcohol, and isopropyl alcohol. It is the etching method of the laminated body.

  According to a fifth aspect of the present invention, there is provided a base metal layer formed of an alloy containing at least one metal selected from nickel and chromium without an adhesive on at least one surface of an insulating substrate, and the base metal layer. In a printed wiring board manufacturing method in which a pattern is formed on the surface of a laminate having a copper coating layer formed on the surface by a semi-additive method, the underlying metal layer exposed after the copper coating layer is removed by etching has an alcoholic hydroxyl group A method for producing a printed wiring board, comprising performing a treatment with a water-soluble organic solvent and then etching and removing with an acidic oxidizing agent containing a permanganate.

  6th invention of this invention is the manufacturing method of the printed wiring board characterized by adding the process of removing a manganese compound with a manganese residue removal liquid after the process process by the acidic oxidizing agent in 5th invention. is there.

  7th invention of this invention is a solution in which the acidic oxidizing agent in 5th and 6th invention contains 0.01-10 weight% permanganate and 0.005-2 weight% hydrochloric acid. This is a method for manufacturing a printed wiring board.

  According to an eighth aspect of the present invention, the organic solvent in the fifth to seventh aspects is at least one alcohol selected from methyl alcohol, ethyl alcohol, n-propyl alcohol, and isopropyl alcohol. It is the manufacturing method of the printed wiring board characterized.

  According to a ninth aspect of the present invention, the insulating substrate according to the fifth aspect is a polyimide film, a polyamide film, a polyester film, a polytetrafluoroethylene film, a polyphenylene sulfide film, a polyethylene naphthalate film, or a liquid crystal polymer. It is a manufacturing method of a printed wiring board characterized by being at least one sort of resin film chosen from a system film.

  According to the method for manufacturing a printed wiring board according to the present invention, by adopting the etching method according to the present invention, in a semi-additive method of a two-layer flexible substrate, wiring can be performed without side etching of the copper layer in an inexpensive and simple process. Since the metal residue between them can be removed and a fine wiring having high insulation reliability can be obtained, the industrial effect is extremely large.

It is a series of sectional views showing a manufacturing process of a flexible wiring board, (a) is a two-layer flexible board, (b) is a resist pattern forming process, (c) is a wiring pattern forming process, (d) is a resist removing process, ( e) is a flash etching step, and (f) is a base metal layer removing step.

  In the present invention, at least one surface of an insulating substrate is formed on a surface of a base metal layer formed of an alloy containing one or more metals selected from nickel and chromium without using an adhesive, and the surface of the base metal layer A method for etching a laminated body of a copper coating layer, wherein after the copper coating layer is removed by etching, a base metal layer exposed is contacted with a water-soluble organic solvent having an alcoholic hydroxyl group and then permanganate A method for etching a laminate, characterized by etching away with an acidic oxidant containing

  For example, a polyimide-based insulator film is used for the insulating substrate, a pattern resist is formed by photolithography on the surface of the copper coating layer of the two-layer flexible substrate in which the base metal layer and the copper coating layer are formed, and further, electrolytic copper plating is performed. Finally, after removing the resist and removing the unnecessary copper coating layer by flash etching, an unnecessary base metal layer between the formed wirings is treated with an acidic etchant containing permanganate, and oxidation Prior to the treatment with the agent, the method for etching a laminate according to the present invention will be described by taking pretreatment with a pretreatment liquid selected from an organic solvent having an amino group or an aqueous solution of the organic solvent.

By providing a base metal layer as a two-layer flexible substrate, it is practiced to ensure adhesion strength that can withstand practical use of the insulator film and the copper coating layer.
However, after the pattern is formed by etching, a trace amount of the metal component of the underlying metal layer that is directly bonded to the insulator film is formed in the insulator between the leads in the space between the leads even after etching and subsequent cleaning processes. It is thought that it remains on the surface layer of the film.
The present inventors, when performing a constant temperature and humidity bias test (HHBT: High Temperature Bias Test) for evaluating the insulation reliability, is one of the causes of the migration of the metal component remaining on the surface layer. It is estimated that there is.

(1) Two-layer flexible substrate a. Insulator film In this invention, when an insulator film is used for an insulating substrate, it can be set as a 2 layer flexible substrate.
The insulator film used was selected from a polyimide film, a polyamide film, a polyester film, a polytetrafluoroethylene film, a polyphenylene sulfide film, a polyethylene naphthalate film, and a liquid crystal polymer film from the viewpoint of heat resistance. At least one kind of thermosetting resin film is preferred. Among these, a polyimide film and a polyamide film are particularly preferable films in that they are suitable for applications that require high-temperature connection in solder reflow or the like.

  The insulator film having a film thickness of 8 to 75 μm can be preferably used. In order to reduce the coefficient of thermal expansion, inorganic materials such as glass fibers and CNTs can be appropriately added to the resin film.

b. Base metal layer The material of the base metal layer formed on the insulating substrate (insulator film) is an alloy containing one or more metals selected from nickel and chromium. The base metal layer may be an alloy in which at least one metal selected from Mo, Ta, Ti, V, Co, and W is added.
The base metal layer preferably contains 7% by mass or more and 25% by mass or less of chromium, and more preferably contains 15% by mass or more and 25% by mass or less of chromium. The alloy of the base metal layer is preferable because it has high corrosion resistance, high adhesion, and heat resistance.
Furthermore, a metal oxide of the base metal layer may be stacked on the base metal layer. The composition of the base metal layer can be appropriately selected in consideration of the insulation reliability in the HHBT test of the two-layer flexible substrate and the printed wiring board and the adhesion to the insulating substrate.

The thickness of the base metal layer of the printed wiring board of the present invention is preferably 3 to 50 nm.
If the underlying metal layer is thinner than 3 nm, it is not preferable because an etching solution infiltrate when wiring is performed and a wiring part is floated, which causes a problem that the wiring peel strength is significantly lowered. Moreover, since it will become difficult to etch if the film thickness becomes thicker than 50 nm, it is not preferable.

c. Copper coating layer A copper coating layer is formed using a sputtering apparatus in which a copper target is mounted on a sputtering cathode. At this time, the base metal layer and the copper coating layer are preferably formed continuously in the same vacuum chamber. When the film is taken out into the atmosphere after forming the base metal layer and the copper coating layer is formed using another sputtering apparatus, it is necessary to sufficiently perform dehydration before film formation.
In addition, it is more preferable that the layer thickness of this copper coating layer is usually in the range of 10 nm to 500 nm. If the thickness of the copper coating layer is 10 nm or more, defect repair by pinholes on the substrate surface is possible. When the thickness is less than 10 nm, it is not preferable because it becomes difficult to supply power when a pattern resist is formed and an electrolytic copper plating process is performed. On the other hand, considering the efficiency of the removal process by flash etching, the thickness of the copper coating layer is preferably 500 nm or less.

(2) Formation of Wiring Pattern Next, the formation of the wiring pattern will be described with reference to FIG.
FIG. 1 is a series of cross-sectional views showing a manufacturing process of a flexible wiring board according to the present invention, where (a) is a two-layer flexible board, (b) is a resist pattern forming process, (c) is a wiring pattern forming process, d) is a resist removing step, (e) is a flash etching step, and (f) is a base metal layer removing step.
In FIG. 1, 1 is an insulator film, 2 is a base metal layer, 3 is a copper coating layer, 4 is a resist pattern, 5 is a wiring pattern, and 6 is a resist pattern removal region.

First, a resist pattern 4 is formed on the copper coating layer 3 by photolithography (FIG. 1B). After the resist pattern 4 is formed, a wiring pattern 5 is formed by an electrolytic copper plating method in a region where the resist is not formed in the resist pattern 4 (that is, a region where the copper coating layer 3 is exposed) (FIG. 1C )).
The wiring pattern 5 is composed of an electrolytic copper plating layer.

After the wiring pattern 5 is formed, the resist pattern 4 is removed. In the region (resist pattern removal region) 6 from which the resist pattern 4 has been removed, the copper coating layer 3 is exposed (FIG. 1D). Next, the copper coating layer 3 exposed in the region 6 is removed by flash etching. The composition of the etching solution to be removed by flash etching is preferably a sulfuric acid concentration of 5 to 50 g / L and a hydrogen peroxide concentration of 10 to 60 g / L.
The underlying metal layer 2 is exposed in the region (resist pattern removal region) 6 from which the copper coating layer 3 has been removed by flash etching (FIG. 1 (e)).

Thereafter, the obtained two-layer flexible substrate is subjected to a treatment (A) in contact with a water-soluble organic solvent having an alcoholic hydroxyl group, and then treated with an acidic oxidizing agent solution containing (B) permanganate. Thus, the base metal layer 2 exposed in the region 6 is removed (FIG. 1F). Examples of the treatment for bringing the remaining base metal layer into contact with a water-soluble organic solvent having an alcoholic hydroxyl group include immersion treatment in an organic solvent and shower treatment with an organic solvent.
Here, immersing the two-layer flexible substrate in (A) a water-soluble organic solvent having an alcoholic hydroxyl group improves the wettability of the exposed base metal layer to the acidic oxidant solution containing permanganate. It is to be done.

  This (A) treatment is an alloy in which the base metal layer contains one or more selected from nickel and chromium, and it is known that the alloy constituting the base metal layer generates a passive state. That is, even if a passive state is formed on the exposed surface of the underlying metal layer until the removal of the copper coating layer, it contains permanganate by contacting with a water-soluble organic solvent having an alcoholic hydroxyl group. This is a process for improving the wettability with an acidic oxidant solution.

Here, the alcoholic hydroxyl group refers to a hydroxyl group that substitutes a hydrogen atom of an aliphatic hydrocarbon, and is a concept different from a hydroxyl group of phenol that substitutes a hydrogen atom such as a benzene ring.
(A) The water-soluble organic solvent having an alcoholic hydroxyl group for treatment is preferably at least one alcohol selected from methyl alcohol, ethyl alcohol, n-propyl alcohol, and isopropyl alcohol.
If the temperature of the organic solvent is room temperature or higher, the removability can be exhibited. However, in the sense of shortening the treatment time, it is preferably around 40 ° C to 55 ° C.

The contact time by a method of immersing in a water-soluble organic solvent having an alcoholic hydroxyl group is preferably 1 second or longer, more preferably 10 seconds or longer. However, even if the contact time with the water-soluble organic solvent having an alcoholic hydroxyl group is increased, the removal of the base metal layer is not affected.
From the viewpoint of productivity, the contact time with the water-soluble organic solvent having an alcoholic hydroxyl group in the molecule is at most 1 minute, more preferably within 30 seconds.

The acidic oxidizing agent containing permanganate is preferably a solution containing 0.01 to 10% by weight permanganate and 0.005 to 2% by weight hydrochloric acid.
When the permanganate concentration is low, the etching time is slow, and even if the permanganate concentration is high, the effect does not change, so the permanganate concentration is more preferably 0.1 to 5% by weight. Also, when the hydrochloric acid concentration is high, the copper wiring is easily dissolved, and at low concentrations, the etching rate is slow and the etching time is increased. Therefore, the hydrochloric acid concentration should be 0.01 to 0.5% by weight. preferable.

(B) The treatment method with an acidic oxidizing agent containing a permanganate for treatment can be either a spray method or an immersion method. The treatment temperature of the acidic etching solution is preferably 20 ° C. to 60 ° C. However, if the temperature is low, the removal of the passive layer tends to be insufficient, and the etching time becomes long. Moreover, since generation | occurrence | production of hydrochloric acid mist will increase and the amount of copper dissolution will also increase when temperature is high, More preferably, it is good to set it as 30 to 50 degreeC.
The treatment time of the permanganate etching solution containing hydrochloric acid is preferably 20 seconds to 3 minutes.
If the time is shorter than 20 seconds, it is insufficient to remove the undissolved residue of the underlying metal layer, and if it is longer than 3 minutes, the amount of copper dissolved increases.

Furthermore, after treatment with the acidic oxidant containing the permanganate, manganese or the like may adhere to the etched surface depending on conditions, and form a metal compound such as an oxide. It is desirable to remove the manganese residue of the alkaline permanganate etching solution with an organic acid aqueous solution such as oxalic acid or ascorbic acid having reducibility, or a commercially available manganese residue removal solution.
After removing the manganese compound with this manganese residue removal solution, if the residue due to the underlying metal layer between the wirings has not been completely removed, it can be treated again with an acidic oxidizing agent containing permanganate. preferable.

  As described above, if the method for manufacturing a printed wiring board of the present invention is used, fine wiring processing can be performed without thinning the leads by side etching the copper layer.

  Up to this point, the manufacturing method in which a two-layer flexible substrate is processed into a printed wiring board by a semi-additive method has been described as an example. As the insulating substrate to be used, in addition to the insulator film, a ceramic plate, a glass plate, a plate made of glass fiber, an epoxy resin, a plastic plate, or the like can be used.

  Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples.

A printed wiring board was produced by a semi-additive method. The preparation procedure is shown.
A 20 wt% Cr—Ni alloy is formed on a base metal layer in a thickness range of 20 to 30 nm by a sputtering method on a polyimide film (manufactured by Toray DuPont, film thickness 50 μm). Next, a pattern resist is formed by photolithography on a two-layer flexible substrate formed by forming a copper film layer in the range of 200 to 350 nm on the underlying metal layer, and then the copper is plated, and then the resist is peeled off. did.

Thereafter, using a commercially available sulfuric acid / hydrogen peroxide soft etchant (trade name: CPE800, manufactured by Hishie Chemical Co., Ltd.), flash etching is performed, and a comb-teeth test board having a copper wiring width / wiring space of 15 μm / 10 μm. Was made.
In order to remove the base metal layer exposed between the wirings of the obtained test substrate, as a pretreatment, (A) treatment of immersing in isopropyl alcohol at room temperature (25 ° C.) for 10 seconds, washing with water, and 1.0. The treatment (B) was performed by immersing in an aqueous solution containing wt% potassium permanganate and 0.3 wt% hydrochloric acid for 60 seconds.
The obtained test board | substrate was observed with the optical microscope, and melt | dissolution of the base metal layer between wiring was confirmed. Moreover, the presence or absence of the etching of the copper wiring was also confirmed with an optical microscope.

Furthermore, about the test board | substrate manufactured in this way, DC60V is applied between terminals in 85 degreeC85% RH environment based on JPCA-ET04 (2007), and resistance is observed for 1000 hours. When the resistance became 10 ⁶ Ω or less, it was judged as short-circuit failure, and HHBT was performed under the condition that it was judged acceptable if it was 10 ⁶ Ω or more after 1000 hours. The endurance time of the target HHBT of this wiring board is 1000 hours.
The test results are shown in Table 1.

  Evaluation was performed in the same manner as in Example 1 except that n-propyl alcohol was used as the isopropyl alcohol. The results are shown in Table 1.

  Evaluation was performed in the same manner as in Example 1 except that ethyl alcohol was used as the isopropyl alcohol. The results are shown in Table 1.

  Evaluation was performed in the same manner as in Example 1 except that methyl alcohol was used as the isopropyl alcohol. The results are shown in Table 1.

(Comparative Example 1)
In Example 1, a test substrate was prepared in the same manner as in Example 1 except that the immersion treatment in alcohol was not performed before the treatment method with an acidic oxidizing agent containing a permanganate. The test substrate was evaluated in the same manner as in Example 1.
The results are shown in Table 1 below.

(Comparative Example 2)
In Example 1, the (A) and (B) treatment for removing the exposed base metal layer was changed to treatment with a commercially available acidic etching solution CH-1920 (etching solution containing hydrochloric acid and sulfuric acid manufactured by MEC Co., Ltd.). Except for this, a test substrate was produced in the same manner as in Example 1, and the test substrate was evaluated.
The results are shown in Table 1 below.

(Comparative Example 3)
Removal of the underlying metal layer exposed after flash etching was carried out in the same manner as in Example 1 except that 1% by weight of potassium permanganate, 5% by weight of hydrochloric acid, and the remaining water etching solution were used. did.
The results are shown in Table 1.

(Comparative Example 4)
The test substrate was removed in the same manner as in Example 1 except that the base metal layer exposed after flash etching was removed by using 0.1 wt% potassium permanganate, 0.3 wt% hydrochloric acid, and the remaining water etching solution. Fabricated and evaluated.
The results are shown in Table 1.

(Reference Example 1)
In Example 1, in order to remove the exposed base metal layer, it was treated with a commercially available acidic etching solution CH-1920 (manufactured by MEC Co., Ltd.), and further containing 5 wt% potassium permanganate and 5 wt% potassium hydroxide. A test substrate was produced and evaluated in the same manner as in Example 1 except that the treatment was performed with an alkaline permanganate solution.
The results are shown in Table 1 below.

In the observation between the wirings in Table 1, the case where the base metal layer did not remain undissolved was indicated as “◯”, and the case where there was an undissolved residue was indicated as “x”.
Moreover, about the result of HHBT, what was not short-circuited for 1000 hours or more was shown as "(circle)", and what was short-circuited within 1000 hours was shown as "*".

  As can be seen from Table 1, in Comparative Example 2 in which only the commercially available acidic etching solution was used to remove the base metal layer, the undissolved residue between the wirings could be removed, but the HHBT was short-circuited within 1000 hours. After the treatment with the commercially available acidic etching solution, the target time was finally reached with HHBT in the case of Comparative Example 3 in which an alkaline permanganate treatment was further performed. In addition, in the acidic permanganate treatment of Comparative Example 1, the undissolved residue of the base metal layer was observed between the wirings, and the base metal layer could not be removed sufficiently. On the other hand, in Example 1 in which acidic permanganate treatment was performed using a hydrophilic solvent as a pretreatment, there was no undissolved residue between the wirings, and good results were obtained even with HHBT.

  As described above, according to the present invention, when forming a copper wiring pattern by a semi-additive method, in particular, according to the etching solution and the etching treatment process according to the present invention, the conventional two-layer flexible process is inexpensive and simple. The remainder of the underlying metal layer component after flash etching by the semi-additive method of the substrate can be dissolved quickly and copper etching can be suppressed, so fine wiring with high insulation resistance can be easily obtained without side etching or damage. The effect is extremely large.

  In addition, the present invention has been described by taking the process of forming a printed wiring board as a two-layer flexible board by a semi-additive method as an example, but at least one side of an insulating board is selected from nickel and chromium without using an adhesive. After the copper coating layer is removed by etching using a method for etching a laminate of a base metal layer formed of an alloy containing one or more metals and a copper coating layer formed on the surface of the base metal layer, The underlying metal layer can be easily removed, and a pattern of a circuit or the like can be easily formed by a laminate of the underlying metal layer and the copper coating layer.

DESCRIPTION OF SYMBOLS 1 Insulator film 2 Base metal layer 3 Copper coating layer 4 Resist pattern 5 Wiring pattern 6 Resist pattern removal area

Claims (9)

A laminate in which a base metal layer formed of an alloy containing one or more metals selected from nickel and chromium without an adhesive is formed on at least one surface of an insulating substrate, and a copper coating layer formed on the surface of the base metal layer An etching method of
An exposed base metal layer after etching away the copper coating layer,
A method for etching a laminate, characterized by performing a treatment with a water-soluble organic solvent having an alcoholic hydroxyl group and then performing etching with an acidic oxidizing agent containing a permanganate to remove the laminate.   The method for etching a laminate according to claim 1, further comprising a step of removing the manganese compound with a manganese residue removing solution after the treatment step with the acidic oxidant.   Etching of the laminated body according to claim 1 or 2, wherein the oxidizing agent is a solution containing 0.01 to 10 wt% permanganate and 0.005 to 2 wt% hydrochloric acid. Method.   4. The laminate according to claim 1, wherein the organic solvent is at least one alcohol selected from methyl alcohol, ethyl alcohol, n-propyl alcohol, and isopropyl alcohol. Body etching method. A laminate in which a base metal layer formed of an alloy containing one or more metals selected from nickel and chromium without using an adhesive on at least one surface of an insulating substrate, and a copper coating layer formed on the surface of the base metal layer In the method for manufacturing a printed wiring board in which a pattern is formed by a semi-additive method on the surface of the body,
An exposed base metal layer after etching away the copper coating layer,
A method for producing a printed wiring board, comprising: performing a treatment with a water-soluble organic solvent having an alcoholic hydroxyl group, and then performing etching with an acidic oxidizing agent containing a permanganate to remove the substrate.   6. The method for producing a printed wiring board according to claim 5, further comprising a step of removing the manganese compound with a manganese residue removing solution after the treatment step with the acidic oxidizing agent.   7. The printed wiring board according to claim 5, wherein the acidic oxidant is a solution containing 0.01 to 10% by weight of permanganate and 0.005 to 2% by weight of hydrochloric acid. Manufacturing method.   8. The organic solvent according to claim 5, wherein the organic solvent is at least one alcohol selected from methyl alcohol, ethyl alcohol, n-propyl alcohol, and isopropyl alcohol. A method for manufacturing a printed wiring board.   The insulating substrate is at least one resin film selected from a polyimide film, polyamide film, polyester film, polytetrafluoroethylene film, polyphenylene sulfide film, polyethylene naphthalate film, and liquid crystal polymer film. The method of manufacturing a printed wiring board according to claim 5, wherein

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