TWI530237B - Etching apparatus and etching method - Google Patents

Description

Etching device and etching method

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

As a technique for forming irregularities in a metal material, an etching technique is used. Particularly in the manufacture of printed wiring boards, etching techniques are widely used because of the advantages of fewer defects and shorter steps required. In the production of a printed wiring board using an etching technique, a metal foil such as a copper foil is laminated on an insulating substrate by a method such as a subsequent method, and the surface of the metal foil is left as a conductor pattern by using a printing technique or a photolithography technique. A resist pattern is partially formed, and then a metal foil which is not protected by the resist pattern is dissolved by etching, thereby forming a conductor pattern.

In recent years, in order to cope with the increase in the size and size of electronic equipment, it is required to refine the conductor pattern on the printed wiring board. In the case of miniaturization, both the insulation reliability and the low conductor resistance coexist. In the case of manufacturing a printed wiring board by an etching technique, in many cases, the cross-sectional shape of the conductor pattern is such that the top width (the width of the surface side of the body pattern) is narrower than the bottom width (the width of the substrate side of the body pattern). Ladder shape. Further, there is a case where the bottom width is narrower than the top width, the center portion is thinner than the upper surface or the lower surface, and the center portion is thicker than the upper surface or the lower surface.

The insulation reliability between adjacent conductor patterns is determined by the closest distance between the two conductor patterns, and the conductor resistance is determined by the sectional area of the conductor pattern. Therefore, when the distance between the 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 coexist with the highest standard. On the other hand, when the cross-sectional shape of the conductor pattern is a trapezoidal shape, an inverted ladder shape, a reel shape, a barrel shape or the like, it is difficult to coexist both high insulation reliability and low conductor resistance with a high standard.

As a technique for obtaining an etching shape close to a rectangle, an etching liquid is proposed in which a compound which reacts with copper to form a substance which hinders etching is added. For example, the following etching liquid is disclosed: an aqueous solution of iron (III) chloride to which thiourea is added (for example, refer to Patent Document 1); an aqueous solution of iron (III) chloride to which dimethyl sulfonium disulfide is added (for example, refer to Patent Document 2) An aqueous solution of iron (III) chloride to which ethylene thiourea is added (for example, refer to Patent Document 3); an aqueous solution of iron (III) chloride to which thiourea and a nonionic or anionic surfactant are added (for example, refer to Patent Document 4) An aqueous solution of copper (II) chloride added with a 2-aminobenzothiazole compound, polyethylene glycol, and a polyamine compound (for example, refer to Patent Document 5); a 2-aminobenzothiazole compound, benzophenone added thereto; A triazole compound, an ethanolamine compound, a glycol ether compound, and an aqueous solution of copper (II) chloride of N-methyl-2-pyrrolidone or dimethylformamide (for example, see Patent Document 6).

Further, in Patent Document 2, an etching method is also mentioned, and it is disclosed that it is preferable to spray an aqueous solution of iron (III) chloride added with a dioxonium disulfide salt in a direction perpendicular or nearly perpendicular to the surface to be etched. . It is known that when another etching liquid is used, the etching liquid is also ejected in a direction as close as possible to the surface to be etched as close as possible, so that the etching shape tends to be close to a rectangle, and in order to achieve this tendency, a nozzle having a narrow injection angle is used (for example, Refer to Patent Document 7). Further, as a technique for obtaining an etching shape close to a rectangle, a technique is proposed in which an etching liquid is ejected together with a gas, thereby causing a droplet of the etching liquid to fly at a high speed (for example, refer to Patent Document 8), or heating the gas in advance, Thereby, the temperature of the etching liquid is prevented from being lowered to improve the etching property (for example, refer to Patent Document 9). Further, in order to obtain an etching shape close to a rectangular shape, it is also proposed that the ejection patterns of the etching liquid ejected from the nozzles do not overlap each other (see, for example, Patent Document 10).

[Patent Document 1] US Patent No. 2746848

[Patent Document 2] Japanese Patent Publication No. Sho 37-15009 (Application Patent Area, page 2, left column, lines 10 to 18)

[Patent Document 3] Japanese Patent Publication No. Sho 39-27516

[Patent Document 4] Japanese Patent Publication No. Sho 50-20950

[Patent Document 5] Japanese Patent Laid-Open No. Hei 6-57453

[Patent Document 6] Japanese Patent Laid-Open Publication No. 2006-274291

[Patent Document 7] Japanese Patent Laid-Open Publication No. SHO 58-221280

[Patent Document 8] Japanese Patent Laid-Open Publication No. 2002-256458

[Patent Document 9] Japanese Patent Laid-Open Publication No. 2006-77299

[Patent Document 10] Japanese Patent Laid-Open Publication No. 2002-69673

In the prior art, a compound which reacts with copper to form a substance which hinders etching is added to the etching liquid to be used. In this technique, as disclosed in Patent Document 2, it is preferably perpendicular or close to the surface to be etched. The etchant is sprayed in the vertical direction. However, in order to eject the etching liquid in a direction perpendicular to any of the portions to be etched, it is necessary to arrange the nozzles at an extremely high density. Since the nozzle requires regular maintenance such as cleaning, an etching device formed by disposing a plurality of nozzles requires complicated maintenance work.

Further, in the prior art, in the technique of ejecting the etching liquid together with the pressurized gas, a large amount of gas is supplied to the etching apparatus, and as a result, a corrosive gas such as hydrogen chloride which is volatilized by the etching liquid is generated in a large amount, or Exhaust gas containing mist of etchant. Therefore, a large-scale exhaust gas treatment device is required, and the composition of the etching liquid changes due to volatilization of hydrogen chloride or the like, so that it is difficult to perform stable etching.

One aspect of the present invention is to solve the problems that arise when implementing the prior art, that is, requiring complicated maintenance work, requiring a large-scale exhaust gas treatment device, or being difficult to perform stable etching, and on the other hand, the cross-sectional shape of the conductor pattern is close. Etching on a rectangle.

The inventors of the present invention have conducted detailed studies on various physical and chemical phenomena accompanying etching, and found that in order to obtain a good etching shape, it is important to increase the etching surface relative to the surface to be etched when the etching liquid is sprayed on the surface to be etched. It is a velocity component in the vertical direction (hereinafter referred to as "vertical velocity component"), and the flow of the etching liquid parallel to the surface to be etched on the surface to be etched is reduced to the same extent or further (hereinafter, referred to as " The velocity component (hereinafter referred to as "surface velocity component") of the surface flow "), the etching apparatus and the etching method described below complete the present invention.

That is, an etching apparatus and an etching method using the apparatus for ejecting an etching liquid from below to an etched surface are disclosed, characterized in that the etching liquid is ejected in such a manner as to be sprayed to the The velocity component of the etching liquid on the etched surface in the direction perpendicular to the surface to be etched reduces the velocity component of the etching liquid flowing in parallel with the surface of the surface to be etched.

Further, as a method of minimizing surface flow as much as possible, an etching apparatus for etching an etchant from below on an etched surface and having a plurality of nozzles disposed thereon has been found and an etching method using the same. The nozzle is a nozzle which is substantially parallel to the surface to be etched, and the nozzle is a nozzle having an angle of 85 to 130, and the nozzle is arranged in such a manner that the area of the ejection pattern of the etching liquid sprayed from each nozzle on the surface to be etched is S _A The ratio (S _A /S _B ) of the area S _B of the region surrounded by the intermediate lines formed by the points on the surface to be etched is 4 or more, and the dots on the surface to be etched are located at and from the nozzle The center point of the nozzle indicated by the intersection of the injection axis and the etched surface, and the center point of each adjacent nozzle indicated by the intersection of the injection axis and the etched surface of each adjacent nozzle are equidistant. Thereby, a conductor pattern in which the surface flow is suppressed and the cross-sectional shape is close to a rectangle can be obtained.

As a result, it has been found that in the etching apparatus and the etching method, it is preferable to dispose the nozzle so that S _A /S _B is 9 or more, and it is more preferable to arrange the nozzle so that S _A /S _B is 16 or more.

As a result, it has been found that in the etching method using the etching apparatus of the present invention, it is preferred to add a compound which reacts with copper to form a substance which inhibits etching, in the etching liquid to be used.

In the etching apparatus of the present invention, since the nozzles are not disposed at a high density, maintenance is easy. Moreover, there is no need for a large-scale exhaust gas treatment device. Further, according to the etching apparatus and the etching method of the present invention, it is possible to stably obtain a conductor pattern in which the surface flow is highly suppressed and the cross-sectional shape is close to a rectangle.

First, the flow of the etching liquid of the prior etching apparatus having the following problem will be described: when the etching liquid is sprayed on the surface to be etched, the profile of the conductor pattern is caused by the influence of the flow of the etching liquid along the surface of the surface to be etched. The shape is a shape that is not a rectangle such as a reel.

Fig. 13 is a schematic side view showing the flow of an etching solution of the prior etching apparatus, and Fig. 14 is a schematic plan view showing the flow of the etching liquid on the surface to be etched. 13d and 14c schematically show the flow of the etching liquid after reaching the surface to be etched. The etching liquid sprayed from the nozzle 13a becomes the spray 13b, and reaches the point 13g and 14a which are opposite to the orifice of the nozzle after reaching the etched surface 13f of the material to be etched 13e (hereinafter, referred to as "the center point of the nozzle" ) Radial flow for the center. Further, in the vicinity of the intermediate lines 13c and 14b adjacent to the nozzles, the liquid ejected from the adjacent nozzles merges and falls by gravity, and is separated from the surface to be etched 13f.

Here, the "middle line between the nozzle and the adjacent nozzle", which is the line on the etched surface 13f, is a line formed by points equidistant from the center points 13g and 14a of the nozzle and the center point of the adjacent nozzle. Specifically, it corresponds to a vertical bisector of a line connecting the center point of the nozzle and the center point of the adjacent nozzle. In order to suppress the surface flow, it is necessary to shorten the distance between the center points 13g and 14a of the nozzle and the point where the above-mentioned junction is formed in the vicinity of the intermediate lines 13c and 14b adjacent to the nozzle (hereinafter, referred to as "the stroke of the surface flow"), in other words, effective It is to narrow the interval from the adjacent nozzles.

However, when the distance from the adjacent nozzle is narrowed, the following problems occur. In other words, the distance between the nozzles and the adjacent nozzles is narrowed, that is, the nozzles are provided in the same area. Of course, the amount of the etching liquid per unit area is increased. When the amount of the etching liquid per unit area is increased, there is a problem in that a thick liquid film is formed on the surface to be etched, and the vertical flow is reduced by the thick liquid film, so that it is difficult to perform etching at a fine interval. Further, the influence of the surface flow is relatively large, and the cross-sectional shape of the conductor pattern is likely to be a reel shape. Moreover, when a large number of nozzles are provided, there is also a problem that the labor required for maintenance is increased.

In order to reduce the amount of etching liquid per unit area, it is theoretically possible to use a nozzle having a small ejection amount in the supply pressure of the etching liquid for the same nozzle (hereinafter referred to as "injection pressure"). In order to reduce the injection amount of the nozzle, it is necessary to reduce the orifice diameter, but the nozzle having a small orifice diameter is liable to be clogged due to the inclusions contained in the etching solution, and if the orifice has little wear or damage, Since the flow rate or the uniformity of the spray pattern is largely affected, it is necessary to change the nozzle frequently to replace the labor or the cost of the parts required for the maintenance of the new product, etc., so that it is completely impractical.

The ejection pressure is lowered, or a structure such as a reduction in ejection pressure is provided inside the nozzle, whereby the amount of etching liquid per unit area can be reduced, but there is a problem that the vertical flow cannot be maintained and the vertical velocity component becomes too small.

Therefore, the inventors of the present invention have found that the above problem can be solved by appropriately defining the relationship between the ejection pattern formed by each nozzle and the arrangement of the respective nozzles, thereby obtaining a conductor pattern in which the surface flow is suppressed and the cross-sectional shape is close to a rectangle. . The details are as follows.

In the present invention, the surface of the plurality of nozzles disposed in the etching apparatus is substantially parallel to the surface to be etched. In the present invention, the ejection pattern refers to a region which is ejected from 95% by mass of the droplets ejected from the nozzle to the inside of the surface to be etched, and is a circular region centering on the ejection axis of the nozzle. In other words, the injection axis of the shaft nozzle located at the center of the circular expansion of the etchant from the nozzle ejection. Fig. 1 is a side view related to a spray pattern, in which an etchant is ejected from a nozzle 1a toward an etched material 1b at an injection angle s. The outline of the jet is 1d, and the distance from the nozzle 1a to the etched surface of the material to be etched 1b is h. Fig. 2 is a plan view relating to a spray pattern, which is a perspective view as seen from the direction of arrow A of Fig. 1. The outline of the spray pattern formed by the nozzle 2a is 2b, and the area S _A of the area (wire line portion) surrounded by the outline 2b can use the spray angle s of the nozzle and the distance h between the nozzle 1a and the etched surface, by S _A = π‧{h‧tan(s/2)} ² means. In the present invention, in order to increase the vertical velocity component as much as possible, it is preferable that the ejection axis 1c of the nozzle is substantially perpendicular to the surface to be etched.

Further, the center point of the nozzle of Fig. 2 is indicated by the intersection of the ejection axis 1c of the nozzle and the etched surface of the material to be etched 1b. In the present invention, the area S _B is an area surrounded by each intermediate line formed by dots on the surface to be etched, and the point on the surface to be etched is located on the ejection axis 1c and the etched surface of the nozzle. The center point of the nozzle indicated by the intersection and the center point of each adjacent nozzle indicated by the intersection of the injection axis of each adjacent nozzle and the surface to be etched are equidistant. The intermediate line is represented by a vertical bisector of the line (the etched surface) of the line connecting the center point of the nozzle and the center point of each adjacent nozzle.

By abutting nozzle is meant a nozzle that is located on the inner side of the intermediate line of any of the other intermediate nozzles. When the distance between the center points of the adjacent nozzles is d, as shown in FIG. 3, when the center point of the nozzle exists at the center point of each division on the square lattice, it is surrounded by the middle line of the adjacent nozzles of the nozzles. The area S _{B of the} area (network line portion) can be obtained by d ² . Further, as shown in FIG. 4, when the center point of the nozzle exists at the center point of each division on the hexagonal lattice, the area (line portion) of the region (network portion) surrounded by the nozzle and the intermediate line of each adjacent nozzle S _B It can be obtained from √3/2d ² ≒0.87d ² .

The average area S _{B of the} plurality of nozzles can be obtained by dividing the area enclosed by the line connecting the center point of the nozzle located at the outermost periphery (hereinafter referred to as "outer circumference line") by the nozzle located inside the outer circumference line. The number. Further, the number of nozzles located inside the outer circumference line is multiplied by the ratio of the injection pattern located inside the outer circumference line to calculate the number. A specific description will be given using the example of FIG. 5. The nozzle 5a in which the entire area of the ejection pattern 5b is located inside the outer peripheral line 5c is referred to as an A group nozzle, and is indicated by a black dot. The nozzle 5a in which the 1/2 of the ejection pattern 5b is located inside the outer peripheral line 5c is referred to as a group B nozzle, and is indicated by a lattice dot. The nozzle 5a in which the 1/4 of the ejection pattern 5b is located inside the outer peripheral line 5c is referred to as a group C nozzle, and is indicated by a hatched dot. There are one group A nozzle, four B group nozzles, and four C group nozzles. Therefore, the number of nozzles located inside the outer circumference line is calculated as: 1+4×1/2+4×1/4=4 The area enclosed by the outer peripheral line 5c is divided by 4, thereby calculating the average area S _B .

In the present invention, in the etching apparatus that ejects the etching liquid using the filling cone nozzle, each nozzle is disposed such that S _A /S _B is 4 or more. It means that the etching liquid reaches the respective points of the etched surface from an average of four or more nozzles. Fig. 6 is a view showing an ejection pattern 6b of an etching liquid ejected from each nozzle 6a when S _A /S _B is 4. It can be seen that the etching liquid ejected from the four or more nozzles reaches substantially all points except the peripheral portion of the surface to be etched. By arranging the nozzles in this way, the surface flow caused by the respective nozzles can be offset, so that an etching shape close to a rectangle can be obtained.

The larger the S _A /S _B is, the more the surface flow will be more highly offset, so that an etched shape closer to a rectangle can be obtained. In particular, when S _A /S _B is 9 or more, it is more preferable, and when S _A /S _B is 16 or more, it is more preferable. When S _A /S _{B is} above the boundary of 9 and 16, it is presumed that the surface flow caused by the nozzle further away is also offset, so that an etching shape closer to a rectangle can be obtained. Fig. 7 is a view showing an ejection pattern 7b of an etching liquid sprayed from each nozzle 7a when S _A /S _B is 9. It can be seen that the etching liquid ejected from the nine or more nozzles reaches all points except the peripheral portion of the surface to be etched.

However, when the S _A /S _B extreme is increased to 60 or more, it is difficult to obtain an effect that the etching shape is close to a rectangle. From this point of view, in the present invention, it is preferred that S _A / S _{B is} less than 60.

In the present invention, if the arrangement of the nozzles is not uniform, a portion where the interval between the nozzles is densely formed flows toward the surface of the sparse portion. From this point of view, in the etching apparatus of the present invention, as shown in the examples of Figs. 3 and 4, it is preferable to arrange the nozzles equally. However, if the effect of the present invention is allowed to be slightly reduced, it is also possible to allow the nozzles to be arranged not strictly. As shown in the specific example, even if the arrangement is as shown in FIG. 8 and FIG. 9, FIG. 8 is that the nozzle 8a is disposed at the center point of the grid in which the two axes are not orthogonal, and FIG. 9 is that the nozzle 9a is disposed on the self-square lattice 9b. The effect of the present invention can also be obtained by slightly deviating from each of the lattice points. In Fig. 8, 8b is the middle line of the adjacent nozzle. In particular, S _A /S _{B is} increased, whereby the influence of the unevenness of the nozzle arrangement due to etching always being etched from a plurality of nozzles can be made small, so it is preferable that S _A /S _B is 9. the above.

Further, as shown in Fig. 10, when one of the nozzles 10a is not evenly arranged, the effects of the present invention can be obtained. Further, in the case where one of the nozzles is partially closed, substantially uniform etching can be continued, and an etching shape close to a rectangle can be obtained, which is an outstanding advantage of the etching method of the present invention. Furthermore, from these viewpoints, S _A /S _B should be large, and 9 or more is preferable.

Further, there may be a difference in the interval between the nozzles that are not close to each other and the adjacent nozzles. As an example, as shown in FIG. 11, the arrangement of the nozzles may be employed such that the interval between the adjacent nozzles 11a is gradually increased toward the conveying direction of the material to be etched.

In the etching method of the present invention, it is preferable to perform etching so that the portion containing the resist pattern in the material to be etched enters the inner side of the outer peripheral line. The reason for this is that the etching liquid is also ejected on the outer side of the outer circumference, but this portion does not have the effect of suppressing the surface flow. Further, when the etching is performed while the material to be etched is being etched, it is difficult to avoid etching in the vicinity of the inlet and the exit of the device, and the etching time in this region is shorter than the total etching time. It does not affect the effect of the present invention.

In the present invention, as the nozzle for ejecting the etching liquid, a filling cone nozzle having an injection angle s of 85 to 130 is used. It is more preferable that the spray angle s is 110 to 130. The "filled-cone nozzle" refers to a nozzle that ejects droplets of the ejected liquid from the nozzle holes at the tip end, and is configured to have a substantially circular shape centering on the ejection axis, and the droplets directly reach the inside thereof. The filling cone nozzle is also called a full cone spray nozzle. As the nozzle, in addition to the filling cone nozzle, there are also fan nozzles, pyramid nozzles, and the like. However, the nozzles have anisotropy in the ejection direction, and thus the surface flow is difficult to offset, and is not suitable for use in the present invention.

Compared with a general nozzle spray angle of 40 to 70°, a fill cone nozzle having a spray angle s of the above range has a wide spray angle. Therefore, it is generally commercially available as a "wide spray angle fill cone nozzle". For example, the GG-W type, the HH-W type, and the QPHA-W type which are available from Spraying Systems Japan Co., Ltd., and the BBXP type which can be obtained from Ikeuchi Co., Ltd. However, the nozzles usable in the present invention are of course not limited to these.

Hereinafter, the reason why it is necessary to use a nozzle having an injection angle of the above range as a nozzle used in the etching apparatus of the present invention will be described.

When a nozzle having an injection angle of less than 85° is used, since S _A becomes small, in order to make S _A /S _B 4 or more, it is necessary to reduce the area S _B . That is, it is necessary to reduce the distance d between the center points of the adjacent nozzles to arrange a large number of nozzles at a high density. Further, in order to realize the preferred aspect of the present invention, i.e., when S _A /S _B is 9 or more or 16 or more, it is necessary to further reduce the nozzle pitch d. In this case, the amount of etching liquid per unit area becomes excessive, and a thick liquid film is formed on the surface to be etched. The vertical velocity component is reduced due to the thick liquid film, which causes a problem that it is difficult to obtain a cross-sectional shape close to a rectangle.

By using a nozzle having a small orifice diameter, the amount of the etching liquid per nozzle is reduced, whereby the liquid film formed on the surface to be etched can be thinned, but the nozzle having a small orifice diameter is contained in the etching solution. The inclusions are liable to cause clogging, which may cause troubles in maintenance work.

Further, by reducing the supply pressure of the etching liquid to the nozzle and reducing the ejection amount of the etching liquid from each nozzle, the liquid film formed on the surface to be etched can be thinned, but when the supply pressure of the etching liquid to the nozzle is lowered, The velocity of the droplets becomes slow, so the vertical velocity component also becomes slow, resulting in a problem that it is difficult to obtain a cross-sectional shape close to a rectangle.

Increasing the distance h between the material to be etched and the nozzle to enlarge the ejection pattern, thereby also expanding S _A , but as disclosed in Patent Document 10, when the distance h between the material to be etched and the nozzle is increased, the ejection is performed. The droplets will decelerate before reaching the material to be etched, so the vertical velocity component will also slow down. In other words, if the distance h between the material to be etched and the nozzle is too small, the amount of the etching liquid per unit area is increased, and it is difficult to perform etching of the fine pattern. If the distance is too large, the droplet speed of the etching liquid is flying. In the process, it is reduced by air resistance, and it is also difficult to perform etching of a fine pattern. Further, when h is large, there is a problem that the workability is deteriorated due to an increase in size of the etching apparatus or an increase in the height of the inlet of the etching material. In view of the above, the distance h is preferably in the range of 50 to 400 mm, preferably in the range of 50 to 300 mm, more preferably 100 to 200 mm.

In the present invention, the nozzle for performing the etching liquid ejection must be resistant to the etching liquid. From this point of view, when an acidic etching solution containing iron (III) chloride or copper (II) chloride as a main component is used as an etching liquid, polypropylene, polyvinylidene fluoride, polytetrafluoroethylene, or the like is used. Plastic nozzles such as polyvinyl chloride. When an alkaline etching solution such as an aqueous ammoniacal sodium chlorite solution is used as the etching liquid, in addition to the above-mentioned plastic nozzle, a name including stainless steel and hastelloy (registered trademark, Haynes International) may be used. A metal nozzle such as a nickel-chromium-molybdenum alloy. The structure of the nozzle used in the present invention is much simpler than the structure of the two-fluid nozzle which is required in the techniques proposed in Patent Documents 8 to 9, and can be produced by a simple method such as injection molding.

In the etching apparatus and the etching method of the present invention, an etching liquid in which a compound which reacts with copper to form a substance which hinders etching is added is used, whereby an etching shape which is very close to a rectangular shape can be obtained in the same manner as in the case of vertically ejecting an etching liquid. As the etching liquid, for example, the etching liquids proposed in Patent Documents 1 to 6 can be used. That is, an aqueous solution of iron (III) chloride to which thiourea is added; an aqueous solution of iron (III) chloride to which a dimethyl sulfonium disulfide salt is added; an aqueous solution of iron (III) chloride to which ethylene thiourea is added; An aqueous solution of iron (III) chloride with thiourea and a nonionic or anionic surfactant; an aqueous solution of copper (II) chloride added with a 2-aminobenzothiazole compound, polyethylene glycol, and a polyamine compound; An aqueous solution of a copper (II) chloride having a 2-aminobenzothiazole compound, a benzotriazole compound, an ethanolamine compound, a glycol ether compound, and N-methyl-2-pyrrolidone or dimethylformamide is added.

An etching liquid containing iron (III) chloride and oxalic acid can be particularly preferably used as the etching liquid to which a compound which reacts with copper to form a substance which inhibits etching is added. Using this etching solution, an etching shape closer to a rectangle can be obtained. In addition, the biodegradability of the thiourea-based compound or the azole-based compound described in Patent Documents 1 to 6 is low, and it is not necessary to use a large-scale drainage treatment device such as ozone treatment or incineration treatment. A component that is fully processed.

For the material to be etched used in the present invention, the same material as that used in the production of a printed wiring board by an etching apparatus or an etching method other than the present invention can be used. That is, a material produced in the following manner can be used as the material to be etched: phenolic paper, epoxy paper, epoxy glass, bismaleimide triazine resin reinforced glass, etc. by means of adhesion, plating, vapor deposition, or the like. On the insulating substrate, a layer containing copper or a copper alloy is laminated, and a resist pattern is formed on the surface thereof by screen printing or photolithography. The method for producing the material to be etched is described, for example, in the Electronic Installation Society, "Printed Circuit Technology Handbook, Third Edition", published by the Nikkan Kogyo Shimbun, May 30, 2006, and Chapter 3. Further, according to the technique of the present invention, it is of course possible to manufacture a printed wiring board having a finer conductor pattern than a printed wiring board manufactured by the prior etching technique, regardless of whether or not the document is described.

In the case of producing a printed wiring board having a very fine conductor pattern having a pitch of 25 μm or less by 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]

[Examples 1 to 22 and Comparative Examples 1 to 10]

In Examples 1 to 11 and Comparative Examples 1 to 5, an etching liquid A to which a compound which reacted with copper was formed to form a substance which inhibits etching was used. In Examples 12 to 22 and Comparative Examples 6 to 10, an etching liquid B to which a compound which inhibits etching was formed after reacting with copper was used.

<Modulation of Etching Solution A>

Add to commercially available 40-millimeter ferric chloride (III) aqueous solution (concentration: 37% by mass) 6.00 kg (2.22 kg as an anhydride) and 252 g of oxalic acid dihydrate (180 g as an anhydride) The water became 30 kg, and an etching liquid A containing 7.4% by mass of iron(III) chloride and 0.60% by mass of oxalic acid was prepared. An electrolytic copper foil having a thickness of 18 μm was allowed to stand in the etching solution, and as a result, only a pale green substance was formed on the surface of the copper foil, and etching was not performed. While stirring the etching solution, the same electrolytic copper foil was immersed therein, and the copper foil was dissolved and disappeared for about 5 minutes.

<Modulation of Etching Solution B>

Adding water to a commercially available 40-m2 aqueous solution of iron (III) chloride (concentration: 37% by mass) of 6.00 kg (2.22 kg as an anhydrate) to prepare a mixture containing 7.4% by mass of ferric chloride ( III) Etching solution B. The electrolytic copper foil was left to be immersed in the etching solution, and the copper foil was dissolved and disappeared in about 5 minutes. While stirring the etching solution, the same electrolytic copper foil was immersed therein, and the copper foil was dissolved and disappeared for about 3 minutes.

<Production of the material to be etched>

Applying and drying a positive liquid resist on a laminate of a polyimide substrate having a thickness of 40 μm and an electrolytic copper foil having a thickness of 18 μm, so that the thickness after drying is 8 μm. The evaluation of the conductor pattern with a width/pitch width of 30 μm/30 μm was followed by development and water washing to prepare an object to be etched.

<etching device>

An etching apparatus was used in which the filling cone nozzles having the injection angles s were arranged in the arrangement pattern of FIG. 4 by the distance d between the nozzles described in Table 1 and the distance h between the surfaces to be etched and the nozzles.

<etching>

By using the etching apparatus described above, the material to be etched is etched while appropriately rotating the conveyed direction of the material to be etched at a speed of 50 cm/min until the cross-sectional view of the conductor pattern 12a on the substrate 12b shown in FIG. Any one of the top width T or the bottom width B is up to 30 μm. The etching time is shown in Table 2. The supply pressure of the etchant to the nozzle was 200 kPa. The etchant injection amount per one nozzle was 1.5 L per minute. After the completion of the etching, the material to be etched was immediately washed with water, immersed in a sodium hydroxide aqueous solution having a concentration of 3% by mass, dissolved and removed, and washed with water, and then immersed in hydrochloric acid having a hydrogen chloride concentration of 5 mass%. Medium, and dried after washing again.

<evaluation>

The material to be etched after the post-treatment was embedded in an acrylic resin, and then cut with a razor to prepare a sample for cross-section observation. The sample was observed using a digital microscope, and the bottom width T, the top width B, and the minimum width w shown in Fig. 12 were measured. In Examples 1 to 11 and Comparative Examples 1 to 5, the amount of shrinkage (the value obtained by subtracting w from any of T and B) was determined. Further, a larger amount of shrinkage indicates that the cross-sectional shape of the conductor pattern is a reel shape. The results of these evaluations are shown in Table 2.

Comparing Examples 1 to 11 with Comparative Examples 1 to 5, it was found that when the etching liquid A containing a compound which reacts with copper to form a substance which inhibits etching is added, the cross-sectional shape obtained by the present invention is not in a reel shape. It is a conductor pattern close to a rectangle. That is, in any of Examples 1 to 11 and Comparative Examples 1 to 5, the maximum value of the difference between the top width and the bottom width was 7 μm, which was relatively small, but the shrinkage amount in Examples 1 to 11 was 0 to 3 μm was relatively small. On the other hand, in Comparative Examples 1 to 5, the shrinkage amount was 6 to 9 μm, which was relatively large, so that the cross section of the conductor pattern was in a reel shape.

Comparing the mutual comparison of Examples 1 to 3 and the comparison of Examples 4 to 10, in the present invention, when S _A /S _B is increased, the amount of shrinkage is smaller, and a conductor pattern having a cross-sectional shape close to a rectangular shape can be obtained. . Specifically, in Examples 4 and 5 in which S _A /S _B is 4 or more and less than 9, the amount of shrinkage is about 2 μm, but in Examples 6 and 7 in which S _A /S _B is 9 or more, The amount of shrinkage was as small as 1 μm, and in Examples 8 to 11 in which S _A /S _B was 16 or more, the amount of shrinkage was zero. In addition, as shown in Embodiment 11, when S _A /S _B is very large, the top width is slightly narrowed.

Further, when Examples 12 to 22 and Comparative Examples 6 to 10 were compared, it was found that when the etching liquid B in which a compound which inhibits etching was formed after reacting with copper was used, the top width and the bottom could be obtained by the present invention. The difference in width is small and the profile is closer to the rectangular conductor pattern. That is, in Examples 12 to 22, the difference between the top width and the bottom width was 12 to 14 μm, whereas in Comparative Examples 6 to 10, the difference between the top width and the bottom width was 16 to 18 μm.

From the comparison of Examples 12 to 14 and the comparison of Examples 15 to 21, it is understood that in the present invention, if S _A /S _B is increased, the difference between the top width and the bottom width is smaller, and the cross-sectional shape can be obtained. Close to the rectangular conductor pattern. Specifically, in Examples 15 to 18 in which S _A /S _{B is} less than 16 and the top width is 16 to 18 μm, in Examples 19 to 21 in which S _A /S _B is 16 or more and less than 60. The top width is 19 μm, so that a conductor pattern having a cross-sectional shape closer to a rectangle can be obtained. In addition, as shown in Example 22, when S _A /S _B is very large, the top width is slightly narrowed.

In Examples 12 to 22 of the etching liquids B using a compound having a substance which inhibits etching after the reaction with copper, the cross-sectional shape improvement from Comparative Examples 6 to 10 was used to form an inhibition after the reaction with copper. The cross-sectional shapes of Comparative Examples 1 to 5 in Examples 1 to 11 of the etching liquid A of the compound of the etched substance were more remarkable. That is, in the case of using an etching liquid to which a compound which inhibits etching is formed after reacting with copper, the etching apparatus of the present invention exhibits a particularly remarkable effect.

[Example 23 and Comparative Example 11]

In Example 23 and Comparative Example 11, except that one nozzle was replaced with a water stop plug, the same procedure as in Example 9 and Comparative Example 3 was carried out. In Example 23, the same results as in Example 9 were obtained. In Comparative Example 11, a strip-shaped underetched portion was produced at a position opposed to the nozzle replaced with the water stop plug.

As is apparent from the embodiment 23, by using the etching apparatus of the present invention, substantially uniform etching can be continued even when a part of the nozzles are closed. On the other hand, as is clear from Comparative Example 11, when the prior etching apparatus was used, even when only a part of the nozzles were closed, the problem of uneven etching was immediately caused.

Further, the nozzles used in the respective embodiments can obtain the same degree of flow as the nozzles used in the prior etching apparatus, and therefore the spray apertures are also the same as those used in the prior etching apparatus. Therefore, the clogging due to the inclusions in the etching solution is also the same frequency as the previous etching device, and the maintenance interval of the nozzles can be the same as that of the previous etching device. Further, since the number of nozzles of the respective embodiments is the same as or less than that of the previous etching apparatus, the time required for one maintenance operation may be the same as or shorter than that of the previous etching apparatus.

The etching apparatus and the etching method of the present invention are applicable not only to the manufacture of printed wiring boards, but also to various industrial applications such as lead frames, precision gears, precision leaf springs, encoder discs or stripes, and various templates. The case of etching of a highly controlled copper or copper alloy is performed.

1a, 2a, 3a, 4a, 5a, 6a, 7a, 8a, 9a, 10a, 11a, 13a. . . nozzle

1b, 13e. . . Etched material

1c. . . Nozzle spray axis

1d. . . Jet silhouette

2b. . . Jet pattern outline

3b, 4b, 8b. . . The middle line with the adjacent nozzle

3c, 4c. . . 1 division by the area S _B enclosed by the middle line of the adjacent nozzle

5b, 6b, 7b. . . Spray pattern

5c. . . Peripheral line

9b. . . Square lattice

12a. . . Conductor pattern

12b. . . Substrate

13b. . . spray

13c, 14b. . . The middle line with the adjacent nozzle

13d, 14c. . . Etching fluid flow

13f. . . Etched surface

13g, 14a. . . Center point of the nozzle

T. . . Top width of the conductor pattern

B. . . Bottom width of the conductor pattern

w. . . The width of the narrowest part of the conductor pattern

A. . . arrow

s. . . Spray angle

h. . . Distance between the etched surface and the nozzle

Figure 1 is a side view associated with a spray pattern.

Figure 2 is a top view of the spray pattern.

Fig. 3 is a view showing a nozzle arrangement in which the nozzles are arranged at the center point of each division of the square lattice, and a region surrounded by the intermediate line of the adjacent nozzles.

Fig. 4 is a view showing a nozzle arrangement in which the nozzle is placed at the center point of each division of the hexagonal lattice, and a line in the middle of the adjacent nozzle.

FIG. 5 is an explanatory view showing an example in which S _A is obtained by dividing the area in the outer circumference line 5c by the number of nozzles.

Fig. 6 is a view showing a spray pattern formed by the nozzle arrangement of Fig. 4 when S _A / S _B is 4.

Fig. 7 is a view showing a spray pattern formed by the nozzle arrangement of Fig. 4 when S _A /S _B is 9.

Fig. 8 is an example of the arrangement of nozzles in which the intervals between the nozzles are not uniform.

Fig. 9 is an example of the arrangement of nozzles in which the intervals between the nozzles are not uniform.

Fig. 10 is a view showing an example of a case where a part of the nozzles is unevenly spaced from the adjacent nozzles.

Fig. 11 is a view showing an example of a case where the interval between adjacent nozzles gradually increases along the conveying direction of the material to be etched.

Figure 12 is a cross-sectional view of a conductor pattern on a substrate.

Figure 13 is a schematic side view showing the flow of an etchant of the prior etching apparatus.

Figure 14 is a schematic plan view showing the flow of an etchant on the etched surface of the prior etching apparatus.

A. . . arrow

S. . . Spray angle

H. . . Distance between the etched surface and the nozzle

1a. . . nozzle

1b. . . Etched material

1c. . . Nozzle spray axis

1d. . . Jet silhouette

Claims (5)

An etching apparatus for ejecting an etchant from below on an etched surface, characterized in that an etchant is ejected in a direction perpendicular to an etched surface with respect to an etchant sprayed onto an etched surface The velocity component reduces the velocity component of the etching liquid flowing in parallel with the surface of the surface to be etched, and the surface of the plurality of nozzles is arranged substantially parallel to the surface to be etched, and the nozzle is a filling cone nozzle having an injection angle of 85° to 130°. The nozzle is disposed in such a manner that the area S _A of the ejection pattern of the etching liquid sprayed from each nozzle on the surface to be etched and the area surrounded by the intermediate lines formed by the points on the surface to be etched are The ratio of the area S _B (S _A /S _B ) is 4 or more, and the point on the surface to be etched is located at the center point of the nozzle indicated by the intersection of the ejection axis and the etched surface of the nozzle, and The center point of each adjacent nozzle indicated by the intersection of the injection axis of the adjacent nozzle and the etched surface is equidistant. An etching apparatus according to claim 1, wherein S _A /S _B is 9 or more. An etching apparatus according to claim 1, wherein S _A /S _B is 16 or more. An etching method which is carried out using an etching apparatus according to any one of claims 1 to 3. The etching method of claim 4, wherein the etching solution contains a compound which reacts with copper to form a substance which inhibits etching.