JP5468064B2 - Etching apparatus and etching method - Google Patents

Description

  The present invention relates to an etching apparatus and an etching method.

  An etching technique is used as a technique for forming irregularities in a metal material. In particular, in the production of a printed wiring board, etching techniques are widely used because there are advantages of less occurrence of defects and a short process time. In the production of printed wiring boards using etching technology, after laminating a metal foil such as copper foil on an insulating substrate by a method such as adhesion, the printing technology is applied to the portion that remains as a conductor pattern on the surface of the metal foil. After forming a resist pattern using a photolithographic technique or the like, a conductive pattern is formed by dissolving and removing a portion of the metal foil that is not protected by the resist pattern by etching.

  In recent years, in order to cope with the advancement and miniaturization of electronic devices, miniaturization of conductor patterns is also required for printed wiring boards. In miniaturization, compatibility between insulation reliability and low conductor resistance is a problem. When manufacturing a printed wiring board by etching technology, the cross-sectional shape of the conductor pattern is a trapezoid whose top width (referred to the width on the surface side of the conductor pattern) is narrower than bottom width (referred to the width on the substrate side of the conductor pattern) There are many cases. In some cases, the bottom width is an inverted trapezoidal shape that is narrower than the top width, the center portion is a pincushion shape that is thinner than the upper surface and the lower surface, and the central portion is a barrel shape that is thicker than the upper surface and the lower surface.

  The insulation reliability between adjacent conductor patterns is determined by the portion where the distance between the two conductor patterns is closest, and the conductor resistance is determined by the cross-sectional area of the conductor pattern. Therefore, when the distance between adjacent conductor patterns is equal at any point in the thickness direction, that is, when the cross-sectional shape of the conductor pattern is rectangular, both high insulation reliability and low conductor resistance can be achieved at the highest level. On the other hand, when the conductor pattern has a trapezoidal shape, inverted trapezoidal shape, pincushion shape, barrel shape, or the like, it is difficult to achieve both high insulation reliability and low conductor resistance at a high level.

  As a technique for obtaining an etching shape close to a rectangle, an etching solution to which a compound that reacts with copper to form a substance that inhibits etching has been proposed. For example, an iron (III) chloride aqueous solution to which thiourea is added (for example, see Patent Document 1), an iron (III) chloride aqueous solution to which formamidine disulfide is added (for example, see Patent Document 2), and a chloride to which ethylenethiourea is added. Iron (III) aqueous solution (for example, see Patent Document 3), iron (III) chloride aqueous solution (for example, see Patent Document 4) to which thiourea and a nonionic or anionic surfactant are added, 2-aminobenzo Copper chloride (II) aqueous solution to which thiazole compound, polyethylene glycol and polyamine compound are added (for example, see Patent Document 5), 2-aminobenzothiazole compound, benzotriazole compound, ethanolamine compound, glycol ether compound and N-methyl-2 -Aqueous copper (II) chloride solution with pyrrolidone or dimethylformamide added (eg For example, an etching solution such as Patent Document 6) is disclosed.

  Patent Document 2 also mentions an etching method, and it is preferable to spray an aqueous solution of iron (III) chloride to which formamidine disulfide salt is added in a direction perpendicular to or close to the surface to be etched. It is disclosed. Even when other etching liquids are used, it is known that the etching shape tends to be close to a rectangle by spraying the etching liquid in a direction almost perpendicular to the surface to be etched. A spray nozzle having a narrow injection angle has been used (see, for example, Patent Document 7). In addition, as a technique for obtaining an etching shape close to a rectangle, a technique for jetting an etchant together with a gas to cause droplets of the etchant to fly at high speed (for example, see Patent Document 8) or heating this gas in advance. Thus, a technique (for example, see Patent Document 9) and the like for preventing the temperature drop of the etching solution and improving the etching property has been proposed. Furthermore, a proposal has been made to obtain an etching shape close to a rectangle by preventing the spray patterns of the etching liquid sprayed from the spray nozzle from overlapping each other (see, for example, Patent Document 10).

US Pat. No. 2,746,848 Japanese Patent Publication No. 37-15209 (Claims, page 2, left column, lines 10-18) Japanese Examined Patent Publication No. 39-27516 Japanese Patent Publication No. 50-20950 JP-A-6-57453 JP 2006-274291 A Japanese Patent Laid-Open No. 58-212280 JP 2002-256458 A JP 2006-77299 A JP 2002-69673 A

  Among the background arts, in the technique using an etching solution to which a compound that forms a substance that inhibits etching by reacting with copper is used, as disclosed in Patent Document 2, the etching solution is perpendicular to the surface to be etched. Or it is preferable to inject in the direction close | similar to this. However, in order for the etching solution to be jetted in a direction near the vertical to any location on the surface to be etched, it is necessary to arrange the spray nozzles at a very high density. Since the spray nozzle requires regular maintenance such as cleaning, an etching apparatus in which a large number of spray nozzles are arranged requires complicated maintenance work.

  Further, among the background arts, in the technique of injecting the etching solution together with the pressurized gas, as a result of supplying a large amount of gas into the etching apparatus, corrosive gas such as hydrogen chloride volatilized from the etching solution, or etching solution A large amount of exhaust gas containing mist is generated. Accordingly, a large-scale exhaust treatment apparatus is required, and stable etching becomes difficult due to a change in the composition of the etching solution due to volatilization of hydrogen chloride or the like.

  The present invention solves these problems that occur in implementing the background art, that is, complicated maintenance work, a large-scale exhaust treatment apparatus, and difficulty in stable etching. Etching is performed so that the cross-sectional shape of the conductor pattern is close to a rectangle.

  In order to obtain a good etching shape, the inventors of the present invention have studied in detail various physical and chemical phenomena associated with etching. The flow of the etching solution parallel to the surface to be etched on the surface to be etched (hereinafter referred to as “the vertical velocity component”) is equal to or higher than that of the velocity component in the direction perpendicular to the surface (hereinafter referred to as “vertical velocity component”). The inventors have found that it is important to reduce the velocity component (hereinafter referred to as “surface velocity component”) of the “surface flow”, and have invented the etching apparatus and etching method described below.

  That is, an etching apparatus for injecting an etchant onto a surface to be etched from below, where a velocity component in a direction perpendicular to the surface to be etched of the etchant sprayed onto the surface to be etched The present inventors have found an etching apparatus characterized by spraying an etching solution so that a velocity component of a flow parallel to the surface is small, and an etching method performed using this apparatus.

Further, as a means for minimizing the surface flow as much as possible, an etching apparatus for injecting an etchant onto a surface to be etched from below, the surface on which a plurality of spray nozzles are arranged and the surface to be etched are substantially parallel. , the spray nozzle is charged and conical spray nozzle噴角85 ° to 130 DEG °, the area S _a of the spray pattern on the surface to be etched in the etching solution is sprayed from each spray nozzle, the injection axis of the spray nozzle to be The center point of the spray nozzle indicated by the intersection with the etching surface and the point on the surface to be etched that is equidistant from the center point of each adjacent spray nozzle indicated by the intersection between the spray axis of each adjacent spray nozzle and the surface to be etched Spray nose so that the ratio (S _A / S _B ) to the area S _{B of} the region surrounded by each intermediate line composed of The present inventors have found an etching apparatus in which a laser is disposed and an etching method performed using this apparatus. Thereby, a surface flow is suppressed and the conductor pattern whose cross-sectional shape is close to a rectangle can be obtained.

In such an etching apparatus and etching method, it is preferable to arrange the spray nozzle so that S _A / S _B is 9 or more, and further to arrange the spray nozzle so that S _A / S _B is 16 or more. I found out.

  In the etching method performed using the etching apparatus of the present invention, it has been found that it is preferable to use an etching solution to which a compound that reacts with copper and forms a substance that inhibits etching is added.

  The etching apparatus of the present invention is easy to maintain because the spray nozzles are not arranged at high density. In addition, a large exhaust treatment device is not required. In the etching apparatus and etching method of the present invention, the surface flow is highly suppressed, and a conductor pattern whose cross-sectional shape is close to a rectangle can be stably obtained.

It is a side view regarding a spray pattern. It is a top view regarding a spray pattern. It is a figure which shows the area | region enclosed with the spray nozzle arrangement | positioning at the time of arrange | positioning the spray nozzle in the center point of each division of a square lattice, and the intermediate line with an adjacent spray nozzle. It is a figure which shows a spray nozzle arrangement | positioning at the time of arrange | positioning a spray nozzle to the center point of each division of a hexagonal lattice, and an intermediate line with an adjacent spray nozzle. The area within the peripheral line 5c the S _A is an illustration of example and dividing by the number of spray nozzles. When S A _/ S _B is 4, it is a diagram showing the spray pattern by the spray nozzle arrangement of FIG. When S A _/ S _B is 9 illustrates a spray pattern by the spray nozzle arrangement of FIG. It is an example of arrangement | positioning of the spray nozzle in which the space | interval between spray nozzles is uneven. It is an example of arrangement | positioning of the spray nozzle in which the space | interval between spray nozzles is uneven. It is a figure which shows an example when the space | interval with an adjacent spray nozzle is not uniform in some spray nozzles. It is a figure which shows an example in case the space | interval between adjacent spray nozzles expands gradually along the conveyance direction of a to-be-etched material. It is sectional drawing of the conductor pattern on a board | substrate. It is a schematic side view of the etchant flow in the conventional etching apparatus. It is a schematic plan view of the etching liquid flow in the to-be-etched surface in the conventional etching apparatus.

  First, when the etchant is sprayed onto the surface to be etched, the shape of the conductor pattern is not a rectangle (such as a pincushion) due to the influence of the surface flow of the etchant along the surface of the surface to be etched. The flow of the etching solution in the conventional etching apparatus having the problem of becoming will be described.

  FIG. 13 is a schematic side view of the etching solution flow in the conventional etching apparatus, and FIG. 14 is a schematic plan view of the etching solution flow on the surface to be etched. Reference numerals 13d and 14c denote an outline of the flow of the etching solution after reaching the surface to be etched. The etching liquid sprayed from the spray nozzle 13a becomes the spray 13b, and after reaching the etching target surface 13f of the material to be etched 13e, points 13g and 14a (hereinafter referred to as "the center point of the spray nozzle") facing the spray nozzle orifice. It flows radially around Then, in the vicinity of the intermediate lines 13c and 14b with the adjacent spray nozzle, it merges with the liquid sprayed from the adjacent spray nozzle, falls due to gravity, and leaves the surface to be etched 13f.

  Here, the “intermediate line between the spray nozzle and the adjacent spray nozzle” is a line on the etching target surface 13f and is equidistant from the center points 13g and 14a of the spray nozzle and the center point of the adjacent spray nozzle. It means a straight line composed of points, and specifically corresponds to a perpendicular bisector of a straight line connecting the center point of the spray nozzle and the center point of the adjacent spray nozzle. In order to suppress the surface flow, the distance between the center points 13g and 14a of the spray nozzle and the joining point in the vicinity of the intermediate lines 13c and 14b with the adjacent spray nozzle (hereinafter referred to as “surface flow process”). ) Is required to be shortened, in other words, it is effective to reduce the distance between adjacent spray nozzles.

  However, when the distance to the adjacent spray nozzle is narrowed, the following problems occur. That is, reducing the distance between adjacent spray nozzles means providing a larger number of spray nozzles in the same area, and naturally the etching liquid injection amount per unit area increases. When the amount of jetted etchant per unit area increases, a thick liquid film is formed on the surface to be etched, and this thick liquid film reduces the vertical flow and makes it difficult to etch fine spaces. To do. In addition, the influence of the surface flow becomes relatively large, and there arises a problem that the cross-sectional shape of the conductor pattern is likely to be a pincushion. In addition, providing a large number of spray nozzles has a problem that labor required for maintenance increases.

  Theoretically, it is possible to use a spray nozzle with a small spray amount even with the supply pressure of the etchant to the same spray nozzle (hereinafter referred to as “spray pressure”) in order to reduce the etchant spray amount per unit area. It is. In order to reduce the spray amount of the spray nozzle, it is necessary to reduce the orifice diameter. However, the spray nozzle with a small orifice diameter is likely to be clogged with impurities contained in the etching solution, and the orifice is slightly worn. Otherwise, the damage greatly affects the flow rate and the uniformity of the spray pattern, so the spray nozzles must be replaced with new ones frequently, and maintenance labor and parts costs increase significantly. .

  The spraying amount per unit area can be reduced by lowering the spray pressure or by providing a structure that reduces the spray pressure inside the spray nozzle, but maintaining the vertical flow It becomes impossible, and the problem that the vertical velocity component becomes too small occurs.

  Therefore, the inventors of the present invention solve the above problems by appropriately determining the relationship between the spray pattern formed by each spray nozzle and the arrangement of each spray nozzle, and suppress the surface flow. It has been found that a conductor pattern having a cross-sectional shape close to a rectangle can be obtained. The details are shown below.

In the present invention, the surface on which the plurality of spray nozzles are arranged in the etching apparatus and the surface to be etched are in a substantially parallel relationship. In the present invention, the spray pattern is a region where 95% by mass of droplets ejected from the spray nozzle land on the inside of the surface to be etched, and is a circular region centered on the spray axis of the spray nozzle. . In other words, the axis located at the center of the circular spread of the etchant sprayed from the spray nozzle is the spray axis of the spray nozzle. FIG. 1 is a side view relating to a spray pattern, in which an etching solution is sprayed from a spray nozzle 1a toward a material to be etched 1b at an injection angle s. The outline of the spray is 1d, and the distance from the spray nozzle 1a to the etched surface of the etched material 1b is h. FIG. 2 is a plan view relating to the spray pattern, and is a perspective view seen from the direction of arrow A in FIG. A contour 2b of the spray pattern by the spray nozzle 2a, the area S _A of a region surrounded by the contour 2b (hatched portion), the distance between the噴角s and spray nozzle 1a and the surface to be etched of the spray nozzles h And S _A = π · {h · tan (s / 2)} ² can be used. In the present invention, in order to increase the vertical velocity component as much as possible, the spray shaft 1c of the spray nozzle is preferably substantially perpendicular to the surface to be etched.

In addition, the center point of the spray nozzle in FIG. 2 is shown by the intersection of the spray axis 1c of the spray nozzle and the etching target surface of the etching target material 1b. In the present invention, the area S _B, each adjacent represented by a point of intersection between the injection axis and the surface to be etched of the center point and each adjacent spray nozzle of the spray nozzles represented by a point of intersection between the injection axis 1c and the surface to be etched of the spray nozzle It is the area of the area | region enclosed by each intermediate line comprised by the point on the to-be-etched surface equidistant from the center point of a spray nozzle. This intermediate line is indicated by a vertical bisector (on the surface to be etched) of each straight line connecting the center point of the spray nozzle and the center point of each adjacent spray nozzle.

The adjacent spray nozzle is a spray nozzle in which a part of an intermediate line with the spray nozzle is located inside an intermediate line with any other spray nozzle. When the distance between the center points of adjacent spray nozzles is d, as shown in FIG. 3, when the center point of each spray nozzle is at the center point of each section on the square lattice, the spray nozzle and each adjacent spray nozzle area S _B of a region surrounded by the median line (hatched portion) is calculated by d ^2. Also, as shown in FIG. 4, when the center point of the spray nozzle is at the center point of each section on the hexagonal lattice, the area (mesh line part) surrounded by the middle line of the spray nozzle and each adjacent spray nozzle area _{S B} is obtained by √3 / 2d ² ≒ 0.87d ^2.

Area S _B of the average for a plurality of spray nozzles, outermost line connecting the center points of the spray nozzles in (hereinafter, referred to as "peripheral line") the area surrounded by, in the number of spray nozzles in the inside It can be obtained by dividing. Note that the number of spray nozzles inside the outer peripheral line is calculated by multiplying the ratio of the spray pattern inside the outer peripheral line. This will be specifically described with reference to the example of FIG. The spray nozzle 5a in which the entire area of the spray pattern 5b is inside the outer peripheral line 5c is called a group A spray nozzle, and is represented by a black circle. The spray nozzle 5a in which 1/2 of the spray pattern 5b is inside the outer peripheral line 5c is referred to as a group B spray nozzle, and is represented by a grid circle. The spray nozzle 5a in which ¼ of the spray pattern 5b is inside the outer peripheral line 5c is referred to as a C group spray nozzle, and is represented by a hatched circle. Since there are one spray nozzle for group A, four spray nozzles for group B, and four spray nozzles for group C, the number of spray nozzles inside the outer circumference is 1 + 4 × 1/2 + 4 × 1/4. = 4 and is calculated, the average of the area S _B is calculated by dividing the area surrounded by the peripheral line 5c in 4.

In the present invention, each spray nozzle is arranged so that S _A / S _B is 4 or more in an etching apparatus that injects an etching solution using a full cone spray nozzle. This means that the etching solution reaches from each point of the surface to be etched from four or more spray nozzles on average. FIG. 6 is a diagram showing a spray pattern 6b of the etching solution sprayed from each spray nozzle 6a when S _A / S _B is 4. It can be seen that the etching solution sprayed from four or more spray nozzles reaches almost all points except the peripheral portion of the surface to be etched. By arranging the spray nozzles in this way, the surface flow caused by each spray nozzle is canceled out, so that an etching shape close to a rectangle is obtained.

The larger S _A / S _B is, the higher the surface flow cancels out, and an etching shape closer to a rectangle is obtained. In _particular, it is preferable to S A / _{S B} is 9 or _more, more preferably S A / _{S B} is 16 or more. When S _A / S _B is greater than or equal to the boundary of 9 and 16, even the surface flow caused by the farther spray nozzles cancel each other, so that an etching shape closer to a rectangle can be obtained. Inferred. FIG. 7 is a diagram showing a spray pattern 7b of the etching solution sprayed from each spray nozzle 7a when S _A / S _B is 9. As shown in FIG. It can be seen that the etching solution sprayed from nine or more spray nozzles reaches all points except the peripheral portion of the surface to be etched.

By the way, when S _A / S _B becomes extremely large as 60 or more, it may be difficult to obtain the effect that the etching shape is close to a rectangle. From this viewpoint, in the present _invention, it is preferable that the S A / _{S B} is less than 60.

In the present invention, if the spray nozzles are not evenly arranged, a surface flow from a portion where the distance between the spray nozzles is dense to a portion where the spray nozzles are sparse will occur. From this point of view, in the etching apparatus of the present invention, it is most preferable to arrange the spray nozzles uniformly as shown in FIGS. 3 and 4. However, if the effect of the present invention is allowed to be slightly diminished, the arrangement of spray nozzles that are not strictly uniform is also allowed. As a specific example, FIG. 8, which is an example in which the spray nozzles 8a are arranged at the center points of a lattice whose two axes are not orthogonal, the spray nozzles 9a are arranged at points slightly deviated from the lattice points of the square lattice 9b. Even if the arrangement shown in FIG. 9 as an example is employed, the effect of the present invention can be obtained. In FIG. 8, 8b is an intermediate line with an adjacent spray nozzle. Especially, by increasing the S A _/ S _B, because it is always a large number of etching with an etchant sprayed from the spray nozzle takes place, since the effect of the spray nozzle arrangement is unequal decreases, S _A / It is preferable that _SB is 9 or more.

Further, as shown in FIG. 10, the effect of the present invention can be obtained even when a part of the spray nozzle 10a is not evenly arranged. Furthermore, even when a part of the spray nozzle is clogged, it is possible to continue the substantially uniform etching and obtain an etching shape close to a rectangle, which is an excellent feature of the etching method of the present invention. It is. From these viewpoints, S _A / S _B is preferably larger and is preferably 9 or more.

  Also, there may be a difference in the distance between adjacent spray nozzles between spray nozzles that are not close to each other. As an example, as shown in FIG. 11, it is also possible to employ a spray nozzle arrangement in which the distance between adjacent spray nozzles 11a is gradually increased in the conveyance direction of the material to be etched.

  In the etching method of the present invention, it is preferable that etching is performed so that a portion having a resist pattern in the material to be etched enters the inside of the outer peripheral line. This is because the etching solution is also sprayed to the outside of the outer peripheral line, but the effect of suppressing the surface flow cannot be obtained in this portion. When etching is performed while conveying the material to be etched, it is inevitable that etching is performed outside the outer peripheral line in the vicinity of the inlet and outlet of the apparatus. However, the etching time in such a region is the etching time. Since it is short compared with the whole, there is no influence on the expression of the effect of the present invention.

  In the present invention, a full cone spray nozzle having an injection angle s of 85 ° to 130 ° is used as a spray nozzle for injecting the etching solution. The jet angle s is more preferably 110 ° to 130 °. The full-cone spray nozzle is a spray nozzle that ejects droplets of the liquid to be ejected in a conical shape from the orifice at the tip, and is configured so that the liquid directly reaches the inside of a substantially circular shape centering on the ejection axis. Say things. The full cone spray nozzle is also called a full cone spray nozzle. As spray nozzles, there are fan spray nozzles, pyramid spray nozzles, etc. in addition to full cone spray nozzles, but since these spray nozzles are anisotropic in the injection direction, the surface flow is difficult to cancel, It is unsuitable for use in the present invention.

  Since the full cone spray nozzle having the jet angle s in the above range has a wide jet angle as compared with 40 to 70 ° which is a jet angle of a general spray nozzle, the “full jet angle full cone spray is usually used. It is sold as a “nozzle”. An example of such a wide-angle filled cone spray nozzle includes model GG-W, model HH-W, model QPHA-W, and model BBXP available from Ikeuchi Co., Ltd. available from Spraying Systems Japan. Of course, the spray nozzles usable in the present invention are not limited to these.

  The reason why the spray nozzle used in the etching apparatus of the present invention must have a spray angle in the above range will be described below.

If噴角is using a spray nozzle of less than 85 °, since the S _A becomes smaller, in order to four or more S A _/ S _B must reduce the area S _B. That is, it is necessary to reduce the distance d between the center points of adjacent spray nozzles and arrange a large number of spray nozzles at high density. Further, in order to S _{A /} S _B is a preferred embodiment of the present invention is to 9 or more or 16 or more, must be further reduced between the spray nozzle distance d. In this case, the etching liquid injection amount per unit area becomes too large, and a thick liquid film is formed on the surface to be etched. Due to this thick liquid film, the vertical velocity component is diminished, and there is a problem that it becomes difficult to obtain a cross-sectional shape close to a rectangle.

  By using a spray nozzle with a small orifice diameter and reducing the spray amount of the etching liquid per spray nozzle, the liquid film formed on the surface to be etched can be made thin. Since clogging with impurities contained in the etching solution is likely to occur, there is a problem that maintenance work becomes complicated.

  In addition, the liquid film formed on the surface to be etched can be made thinner by lowering the supply pressure of the etching liquid to the spray nozzle and reducing the injection amount of the etching liquid from each spray nozzle. When the supply pressure of the etching solution to the nozzle is lowered, the speed of the liquid droplets is slowed down, so that the vertical velocity component is slowed down, resulting in a problem that it becomes difficult to obtain a cross-sectional shape close to a rectangle.

By expanding greatly to spray pattern distance h between the object to be etched and the spray nozzle, but it is also possible to increase the S _A, as disclosed also Patent Document 10, the material to be etched and between the spray nozzle When the distance h is increased, the jetted droplets are decelerated before reaching the material to be etched, so that the vertical velocity component also becomes slow. That is, if the distance h between the material to be etched and the spray nozzle is too small, the injection amount of the etching liquid per unit area increases, and it may be difficult to etch a fine pattern. Drop velocity may be diminished by air resistance during flight, making it difficult to etch fine patterns. Furthermore, when h is large, problems such as an increase in the size of the etching apparatus and a deterioration in workability due to an increase in the height of the material to be etched are raised. Considering the above, the distance h is preferably in the range of 50 to 400 mm, more preferably in the range of 50 to 300 mm, and even more preferably 100 to 200 mm.

  In the present invention, the spray nozzle used for spraying the etchant must be resistant to the etchant. From this point of view, when an acidic etchant mainly composed of iron (III) chloride, copper (II) chloride or the like is used as an etchant, plastics such as polypropylene, polyvinylidene fluoride, polytetrafluoroethylene, and polyvinyl chloride are used. A spray nozzle is used. When an alkaline etching solution such as an aqueous ammoniacal sodium chlorite solution is used as the etching solution, in addition to the plastic spray nozzle, nickel-chromium distributed under the names of stainless steel and Hastelloy (registered trademark, Haynes International) -It is also possible to use a spray nozzle made of metal such as molybdenum alloy. The spray nozzle used in the present invention has a much simpler structure than the two-fluid spray nozzle required for the techniques proposed in Patent Documents 8 to 9, and is manufactured by a simple method such as injection molding. be able to.

  In the etching apparatus and the etching method of the present invention, by using an etching solution to which a compound that reacts with copper to form a substance that inhibits etching is added, the etching solution is formed into a very rectangular shape as in the case where the etching solution is injected vertically. A close etching shape can be obtained. As such an etchant, for example, an etchant proposed in Patent Documents 1 to 6 can be used. That is, iron (III) chloride aqueous solution to which thiourea was added, iron (III) chloride aqueous solution to which formamidine disulfide salt was added, iron (III) chloride aqueous solution to which ethylenethiourea was added, thiourea and nonionic or anionic Iron (III) aqueous solution to which a surfactant is added, 2-aminobenzothiazole compound, polyethylene glycol, and copper (II) chloride aqueous solution to which a polyamine compound is added, 2-aminobenzothiazole compound, benzotriazole compound, ethanol Examples thereof include an aqueous copper (II) chloride solution to which an amine compound, a glycol ether compound, and N-methyl-2-pyrrolidone or dimethylformamide are added.

  An etchant containing iron (III) chloride and oxalic acid is particularly preferably used as an etchant to which a compound that forms a substance that inhibits etching by reacting with copper is added. By using such an etching solution, an etching shape closer to a rectangle can be obtained. In addition, biodegradability such as thiourea compounds and azole compounds described in Patent Documents 1 to 6 is low, and sufficient treatment is possible without using a large-scale wastewater treatment apparatus such as ozone treatment or incineration treatment. There is also an advantage of not including impossible components.

  As the material to be etched used in the present invention, the same material as in the production of a printed wiring board using an etching apparatus or etching method other than the present invention can be used. That is, a layer made of copper or a copper alloy is laminated on an insulating substrate such as paper phenol, paper epoxy, glass epoxy, glass reinforced bismaleimide triazine resin, etc. by a method such as adhesion, plating, vapor deposition, etc. A material provided with a resist pattern by a method such as screen printing or photolithography can be used as the material to be etched. A method for producing such a material to be etched is described in Chapter 3 of May 30, 2006, published by Nikkan Kogyo Shimbun, edited by the Japan Institute of Electronics Packaging, "Printed Circuit Technology Handbook 3rd Edition", for example. In addition, according to the technique of this invention, it cannot be overemphasized that a printed wiring board with a finer conductor pattern can be manufactured rather than what was manufactured by the conventional etching technique irrespective of description of this literature.

  When a printed wiring board having a particularly fine conductor pattern with a space width of 25 μm or less is manufactured according to the present invention, the thickness of the resist pattern layer is preferably 10 μm or less. That is, it is preferable to use a dry film resist having a thickness of 10 μm or less, or to apply a liquid resist so that the thickness after film formation is 10 μm or less.

[Examples 1 to 22 and Comparative Examples 1 to 10]
Examples 1 to 11 and Comparative Examples 1 to 5 use the etching solution A to which a compound that reacts with copper to form a substance that inhibits etching is added. Examples 12 to 22 and Comparative Examples 6 to 10 use an etching solution B to which a compound that reacts with copper and forms a substance that inhibits etching is not added.

<Preparation of Etching Solution A>
Commercially available 40 ° Baume iron chloride (III) aqueous solution (concentration: 37% by mass) 6.00 kg (2.22 kg as anhydride), 252 g of oxalic acid dihydrate (180 g as anhydride) was added water to 30 kg, An etching solution A containing 7.4% by mass of iron (III) chloride and 0.60% by mass of oxalic acid was prepared. When an electrolytic copper foil having a thickness of 18 μm was allowed to stand still in such an etching solution, a light green substance was formed on the surface of the copper foil, and etching did not proceed. When the same electrolytic copper foil was immersed while stirring the etching solution, the copper foil dissolved and disappeared in about 5 minutes.

<Preparation of etching solution B>
Etching solution containing 7.4% by mass of iron (III) chloride by adding water to 6.00kg (2.22kg as anhydrous) of commercial 40 ° Baume iron chloride (III) solution (concentration: 37% by mass) B was prepared. When the electrolytic copper foil was allowed to stand still in the etching solution, the copper foil dissolved and disappeared in about 5 minutes. When the same electrolytic copper foil was immersed while stirring the etching solution, the copper foil dissolved and disappeared in about 3 minutes.

<Preparation of material to be etched>
A positive liquid resist is applied and dried on a laminated material obtained by laminating a polyimide insulating substrate having a thickness of 40 μm and an electrolytic copper foil having a thickness of 18 μm so that the thickness after drying becomes 8 μm, and the line width / space width = 30 μm / 30 μm. After the evaluation conductor pattern was exposed, it was developed and washed with water to prepare an etched material.

<Etching device>
An etching apparatus in which a full cone spray nozzle having a spray angle s with a distance d between spray nozzles and a distance h between the surface to be etched and the spray nozzle described in Table 1 is arranged according to the arrangement pattern of FIG. 4 was used. .

<Etching>
Using the above etching apparatus, either the top width T or the bottom width B in the cross-sectional view of the conductor pattern 12a on the substrate 12b shown in FIG. 12 while appropriately reversing the transport direction of the material to be etched at a speed of 50 cm / min. Etching was performed until the wider side became 30 μm. The etching time is shown in Table 2. The supply pressure of the etching solution to the spray nozzle was 200 kPa. The amount of etching solution sprayed per spray nozzle is 1.5 L / min. After the etching is completed, as a post-treatment, the material to be etched is immediately washed with water, immersed in a 3% by weight sodium hydroxide aqueous solution to dissolve and remove the resist pattern, washed again with water, and then immersed in hydrochloric acid with a hydrogen chloride concentration of 5% by weight. Then, it was washed again with water and dried.

<Evaluation>
The post-processed material to be etched was embedded with an acrylic resin and then cut with a razor to prepare a cross-sectional observation sample. The sample was observed using a digital microscope, and the bottom width T, top width B, and minimum width w shown in FIG. 12 were measured. About Examples 1-11 and Comparative Examples 1-5, the amount of constriction (value which subtracted w from the smaller one of T and B) was calculated | required. A large amount of constriction indicates that the cross-sectional shape of the conductor pattern is a pincushion shape. Table 2 shows the results of these evaluations.

  As can be seen by comparing Examples 1 to 11 and Comparative Examples 1 to 5, when the etching solution A added with a compound that forms a substance that inhibits etching by reacting with copper is used, according to the present invention, a cross-sectional shape is obtained. It can be seen that a conductive pattern close to a rectangle is obtained without forming a pincushion shape. That is, in any of Examples 1 to 11 and Comparative Examples 1 to 5, the difference between the top width and the bottom width is as small as 7 μm at maximum, whereas in Examples 1 to 11, the amount of constriction is as small as 0 to 3 μm. In Comparative Examples 1 to 5, the amount of constriction is as large as 6 to 9 [mu] m, and the cross section of the conductor pattern is pinched.

As can be seen from the comparison between Examples 1 to 3 and the comparison between Examples 4 to 10, in the present invention, when S _A / S _B is increased, the amount of constriction is smaller and the conductor pattern is close to a rectangle. You can see that Specifically, in Examples 4 and 5 where S _A / S _B is 4 or more and less than 9, the amount of constriction is about 2 μm, but in Examples 6 and 7 where S _A / S _B is 9 or more, the amount of constriction is In Examples 8 to 11 in which S _A / S _B is 16 or more, the amount of constriction is 0, which is as small as 1 μm. In addition, when S _A / S _B is very large as in Example 11, it can be seen that the top width is slightly narrowed.

  In addition, as can be seen by comparing Examples 12 to 22 and Comparative Examples 6 to 10, the present invention is also applicable to the case where an etching solution B that does not add a compound that reacts with copper to form a substance that inhibits etching is used. Thus, it can be seen that a conductor pattern having a small difference between the top width and the bottom width and having a cross section closer to a rectangle can be obtained. That is, in Examples 12 to 22, the difference between the top width and the bottom width is 12 to 14 μm, whereas in Comparative Examples 6 to 10, the difference between the top width and the bottom width is as large as 16 to 18 μm.

As can be seen from a comparison of Comparative and Example 15-21 mutual Examples 12 to 14 each other, in the present invention, an increase in the S A _/ S _B, more differences top width and the bottom width is small, the cross-sectional shape is rectangular It can be seen that a conductor pattern close to is obtained. _{Specifically,} the top in the S A / _{S B} is compared in a top width 16~18μm Example 15-18 under _16, Example 19~21 _S A / S _B is less than 16 or more 60 It can be seen that a conductor pattern having a width of 19 μm and a cross-sectional shape closer to a rectangle is obtained. In addition, when S _A / S _B is very large as in Example 22, it can be seen that the top width is slightly narrowed.

  Compared with the cross-sectional shape improvement from Comparative Examples 6 to 10 in Examples 12 to 22 using an etching solution B that does not add a compound that reacts with copper and forms a substance that inhibits etching, etching reacts with copper. The improvement in cross-sectional shape from Comparative Examples 1 to 5 in Examples 1 to 11 using the etching solution A to which a compound that forms a substance that inhibits the above was added is remarkable. That is, the etching apparatus of the present invention exhibits a particularly remarkable effect when an etching solution to which a compound that reacts with copper to form a substance that inhibits etching is added is used.

[Example 23 and Comparative Example 11]
Example 23 and Comparative Example 11 were carried out in the same manner as Example 9 and Comparative Example 3, respectively, except that one spray nozzle was replaced with a stopper plug. For Example 23, the same result as in Example 9 was obtained, but in Comparative Example 11, a strip-like insufficient etching portion was generated at a position opposite to the spray nozzle replaced with a stopper plug.

  As can be seen from Example 23, by using the etching apparatus of the present invention, even when some spray nozzles are blocked, substantially uniform etching can be continued. On the other hand, as can be seen from Comparative Example 11, when a conventional etching apparatus is used, there is a problem that etching becomes non-uniform immediately even if only some spray nozzles are blocked.

  In addition, since the spray nozzle used for each Example can obtain the flow volume comparable as what is used for the conventional etching apparatus, the orifice diameter is also the same as what is used for the conventional etching apparatus. Therefore, the occurrence of clogging due to contaminants in the etching solution occurs at the same frequency as that of the conventional etching apparatus, and the maintenance interval of the spray nozzle can be the same as that of the conventional etching apparatus. In addition, since the number of nozzles arranged in each embodiment is the same as or less than that of the conventional etching apparatus, the time required for one maintenance operation can be the same as or shorter than that of the conventional etching apparatus.

  The etching apparatus and etching method of the present invention are not only used in the production of printed wiring boards, but also in various other industrial applications such as the production of lead frames, precision gears, precision leaf springs, encoder disks and stripes, and various stencils. Can be suitably used when it is necessary to control the etching of copper or a copper alloy controlled in a uniform manner.

[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1a Spray nozzle 1b To-be-etched material 1c Spray nozzle injection axis 1d Spray outline 2a Spray nozzle 2b Spray pattern outline 3a Spray nozzle 3b Intermediate line with adjacent spray nozzle 3c Area S surrounded by intermediate line with adjacent spray nozzle One section of _B 4a Spray nozzle 4b Middle line with adjacent spray nozzle 4c Area S surrounded by intermediate line with adjacent spray nozzle 5B One section of _B 5a Spray nozzle 5b Spray pattern 5c Perimeter line 6a Spray nozzle 6b Spray pattern 7a Spray Nozzle 7b Spray pattern 8a Spray nozzle 8b Middle line with adjacent spray nozzle 9a Spray nozzle 9b Square lattice 10a Spray nozzle 11a Spray nozzle 12a Conductor pattern 12b Substrate 13a Spray nozzle 13b Spray 13c Intermediate line with adjacent spray 13d Flow of etching solution 13e Material to be etched 13f Surface to be etched 13g Center point of spray nozzle 14a Center point of spray nozzle 14b Intermediate line with adjacent spray 14c Flow of etching solution T Conductor pattern B Top width of the conductor B Bottom width of the conductor pattern w Width of the narrowest part of the conductor pattern

Claims (5)

An etching apparatus for spraying an etching solution onto a surface to be etched from below, wherein a surface on which a plurality of spray nozzles are arranged and a surface to be etched are substantially parallel, and the spray nozzle has an injection angle of 85 ° to 130 °. a charge cone spray nozzles, the area S _a of the spray pattern on the surface to be etched in the etching solution ejected from the spray nozzle, of the spray nozzle represented by a point of intersection between the injection axis and the surface to be etched of the spray nozzle A region surrounded by each intermediate line composed of a point on the etched surface that is equidistant from the central point of each adjacent spray nozzle indicated by the center point and the intersection of the spray axis of each adjacent spray nozzle and the etched surface An etching apparatus in which a spray nozzle is arranged so that a ratio (S _A / S _B ) to an area S _B of 4 becomes 4 or more. S _A / _{S B} is an etching apparatus according to claim 1, wherein 9 or more. S _A / _{S B} is an etching apparatus according to claim 1, wherein 16 or more. Etching method and performing by using an etching apparatus according to any one of claims 1-3. The etching method according to claim 4 , wherein the etching solution contains a compound that reacts with copper to form a substance that inhibits etching.

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