JPH10280170A - Method and apparatus for forming etching mask - Google Patents

Abstract

(57) [Problem] To prevent a situation where a disadvantage that is disadvantageous during an etching process is present in an etching mask, and to form a precise fine line pattern on a metal surface. A step of preparing an original image corresponding to a pattern of an etching mask, a step of converting the original image into a toner image using electrophotography, and a step of transferring the toner image onto a surface of a metal to be etched. And

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for forming an etching mask using an electrophotographic technique, and more particularly to an etching mask suitable for manufacturing a precision film-shaped printed circuit board. The present invention relates to a forming method and an apparatus.

[0002]

2. Description of the Related Art Generally, when various patterns are formed by selectively removing a metal surface, an etching technique is used. This etching process requires an etching mask forming process as a pre-process.

For example, in the case of manufacturing a printed wiring board, the first or second etching mask forming method described below has been conventionally employed.

FIG. 8 shows a first etching mask forming method.
(A) to FIG. 8 (d). In FIG.
Reference numeral 0 denotes a printed wiring base, 101 denotes an insulating layer, 102 denotes a metal layer, 103 denotes a photosensitive layer, 104 denotes a negative film, and 105 denotes an etching mask.

In a first step, a photosensitive layer 103 is formed on a surface of a metal layer 102 laminated on at least one surface of an insulating layer 101 using a resist ink or a dry film.

In the next step, a negative film 104 is arranged on the photosensitive layer 103 and irradiated with UV light to expose the exposed film 104a.
And the non-exposed portion 104b are formed.

[0007] In the last step, an etching mask 105 is formed by developing using the difference in solubility of the exposed portion 104a and the non-exposed portion 104b in a developing solution.

FIG. 9 shows a second etching mask forming method.
(A) to FIG. 9 (b). In FIG.
0 is a printed wiring board, 101 is an insulating layer, and 102 is a metal layer.

In this method, an etching mask 105 is directly formed on the surface of the metal layer 102 by using a method such as screen printing, gravure printing, or offset printing.

[0010]

However, in the case of the above-mentioned first method, the steps are complicated, the equipment cost is high, and the number of steps is large, so that the product cost is high. Furthermore, when applied to a substrate having poor mechanical strength such as a film, there is a problem that it is difficult to improve the yield of products because defects such as wrinkles are likely to occur during formation of the photosensitive layer.

On the other hand, in the case of the second method, since the etching mask is formed by the above-described direct printing method, it is difficult to form an etching mask suitable for a fine line pattern of 0.3 mm or less. Further, since the thickness of the etching mask is small and defects such as pinholes are likely to occur, problems such as lack of reliability of the etching mask occur. In particular, when a UV ink is used as a printing ink, there is a problem that adhesion to an insulating substrate is poor and defects such as pinholes occur frequently. Furthermore, when an oxidatively polymerizable ink is used as a printing ink, a problem arises in that the drying time must be lengthened and the ink cannot be applied to a substrate having no heat resistance.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a simple process that does not require a large capital investment and that can form a fine pattern. And a method and apparatus for forming a highly reliable etching mask.

[0013]

According to the invention described in claim 1 (or claim 7) of this application, a step (or means) of preparing an original image corresponding to a pattern of an etching mask is provided.
Converting the original image into a toner image using electrophotography (or means); and transferring the toner image onto a surface of a metal to be etched (or means).
And a method (or apparatus) for forming an etching mask.

According to the invention described in claim 1 (or claim 7) of this application, a fine and highly reliable etching mask can be formed in a simple process without requiring a large capital investment. .

[0015] The invention described in claim 2 (or claim 8) of this application is the invention according to claim 1 (or claim 7) of the present application, in which the transfer is performed on the surface of the metal prior to the transfer. A method (or apparatus) for forming an etching mask, comprising a step of performing a pretreatment for promoting adhesion of toner.

According to the invention described in claim 2 (or claim 8) of this application, the pretreatment performed on the surface of the metal prior to the transfer of the toner image removes the defects disadvantageous during the etching process. A situation that occurs in the mask can be prevented beforehand.

According to the invention described in claim 3 (or claim 9) of this application, in the invention described in claim 2 (or claim 8) of this application, the pretreatment is a surface activation treatment by corona discharge. The method (or apparatus) for forming an etching mask, characterized in that:

According to the invention described in claim 3 (or claim 9) of this application, electrostatic adhesion of toner is performed by a surface activation treatment by corona discharge performed on a metal surface prior to transfer of a toner image. Is promoted, it is possible to prevent a situation where a disadvantage that is disadvantageous during the etching process is generated in the etching mask.

The invention described in claim 4 (or claim 10) of the present application is the invention according to claim 2 (or claim 8) of the present application, wherein the pretreatment is a mechanical surface roughening treatment. A method (or an apparatus) for forming an etching mask.

According to the invention described in claim 4 (or claim 10) of this application, the adhesion of the toner is promoted by the mechanical surface roughening treatment performed on the metal surface prior to the transfer of the toner image. Therefore, it is possible to prevent a situation that a disadvantage that is disadvantageous at the time of the etching process is generated in the etching mask.

The invention described in claim 5 (or claim 11) of this application is equivalent to claim 2 (or claim 12) of this application.
In the invention described in (1), there is provided a method (or apparatus) for forming an etching mask, wherein the pretreatment is a chemical roughening treatment.

According to the invention described in claim 5 (or claim 11) of this application, the adhesion of the toner is promoted by the chemical surface roughening treatment performed on the metal surface prior to the transfer of the toner image. Therefore, it is possible to prevent a situation that a disadvantage that is disadvantageous at the time of the etching process is generated in the etching mask.

The invention described in claim 6 (or claim 12) of this application can be applied to claims 1 to 5 (claims 7 to 1) of this application.
1) The method according to any one of 1) to 3), wherein the metal is a metal foil of a printed circuit board.

According to the invention described in claim 6 (or claim 12) of this application, after forming an etching mask having excellent resolution as a toner image, this toner image is transferred onto a metal foil of a printed circuit board. By doing so, it is possible to form an etching mask to a predetermined thickness on the metal foil of the printed circuit board. Further, a pretreatment performed on the surface of the metal foil of the printed circuit board prior to the transfer of the toner image can prevent a situation in which an etching mask is disadvantageous during etching processing.

According to a thirteenth aspect of the present invention, in the method for forming an etching mask according to any one of the first to twelfth aspects, the toner mainly comprises an io monomer resin. Or in the device.

According to the thirteenth aspect of the present invention, it is possible to form an etching mask suitable for finer etching with higher reliability, in combination with the chemical properties of the toner itself.

[0027]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

As described above, in the method of forming an etching mask according to the present invention, a step of preparing an original image corresponding to the pattern of the etching mask, and a step of converting the original image into a toner image using electrophotography And a step of transferring the toner image to a surface of a metal to be etched.

One embodiment of the method of the present invention (hereinafter referred to as a first embodiment) is shown in FIGS. 1 (a) to 1 (d). In the first embodiment, the method of the present invention is applied to form an etching mask on a film-shaped printed wiring board.

In the figures, 1 is a film-shaped printed wiring substrate, 2 is an insulating layer made of a 25 μm thick polyethylene terephthalate (PET) film, and 3 is 15 μm.
Reference numeral 4 denotes a surface treatment layer, 5 denotes a toner image, and 6 denotes an etching mask.

First, in a first step, a metal layer (aluminum foil) 3 of a film-shaped printed wiring substrate 1 (see FIG. 1A) is used as a pretreatment prior to transfer of a toner image by electrophotography described later. Is activated by corona discharge to form a corona-charged surface treatment layer 4 (see FIG. 1B).

This preprocessing is performed for the following reasons. In charging a metal which is an electrically good conductor, it is extremely difficult to charge a large charge because the electrolytic saturation time of the metal is very short. For this reason, when the toner image 5 is transferred to the film-shaped printed wiring substrate 1 by an electrophotographic apparatus to be described later, the amount of charge is insufficient, so that a clear image cannot be obtained or the toner does not move. May occur. This step is a step provided for applying a strong electric field to the film-shaped printed wiring substrate 1 to obtain a sufficient charge amount for the movement of the toner. This step can be realized, for example, by passing the film-shaped printed wiring substrate 1 into an ion shower space formed by applying a discharge power of ²⁰ to 30 W / m ² / min to the ceramic electrode, Thereby, a sufficient amount of charges can be charged on the metal layer 3. However, since the saturation speed of the metal is high, it is desirable that the time interval between this step and the second step for transferring the next toner image be as short as possible.

Next, in a second step, a toner image 5 corresponding to a circuit pattern developed on a photoreceptor by an electrophotographic apparatus described later is transferred onto the surface of the charged metal layer 3. That is, as will be described later in detail, original image information corresponding to an etching pattern prepared in advance is converted into a toner image using electrophotography, and this toner image is placed on the surface of the charged metal layer 3. It is transferred (see FIG. 1 (c)).

The form in which the original image information corresponding to the etching pattern is provided may vary depending on the exposure method employed by the electrophotographic apparatus. For example, if a projection type exposure method used in a PPC copier or the like is adopted as the exposure method, the original image information can be provided as a paper or sheet on which an original image corresponding to the etching pattern is printed. Also, if a beam scanning type exposure system employed in a laser beam printer or the like is employed as the exposure system, the original image information can be provided as various types of computer-readable image information. Of course, this image information
It may be stored in various recording media (hard disk, MO, DVD, etc.), read out by a computer as needed, and provided for exposure.

Next, in the third step, the deposited toner constituting the toner image 5 is removed at a high temperature of, for example, about 150 ° C.
Heating is performed for a long time of about 0 minutes to melt the styrene acrylic resin, which is the main component of the toner, and fix the toner image 5 on the surface of the metal layer 3 (surface treatment layer 4).

The fixing process involving long-time high-temperature heating is performed for the following reason. The heat fixing process is naturally adopted also in the electrophotographic technology employed in PPC copiers and the like, but when such a conventional heat fixing process is applied to the method of forming an etching mask which is the object of the present invention. However, it is difficult to remove defects such as pinholes generated in the circuit pattern. On the other hand, according to the fixing process involving long-time heating according to the present invention, a temperature and time sufficient for melting the resin component constituting the toner are given, so that the pinhole or the like generated in the previous transfer process is provided. Is repaired by the molten resin, and the bonding between the base material 1 and the toner image 5 is further strengthened, thereby forming a highly reliable etching mask 6 that can sufficiently withstand the subsequent etching process. (See FIG. 1D).

The printed wiring board 1 used in the first embodiment uses an aluminum foil as the metal layer 3, but may use a copper foil instead. For example, a substrate material such as polyimide or glass epoxy having a thickness of about 0.1 mm can be used.

FIG. 2 shows an apparatus (continuous manufacturing facility) for carrying out the method according to the first embodiment.
In the figure, reference numeral 1 denotes the film-shaped printed wiring substrate described above, 7 denotes a roll for feeding the film-shaped printed wiring substrate 1, 8 denotes a roll for winding the film-shaped wiring substrate, 9
Is a feed roller, 10 is a charging device, 11 is an electrophotographic device,
Reference numeral 12 denotes a heat fixing device, and reference numeral 13 denotes a feed roller.

The charging device 10 is provided as a pre-processing device for the electrophotographic device 11, and performs corona discharge on the film-shaped printed wiring substrate 1 before transferring a toner image in the electrophotographic device 11, which will be described later. This is to activate the surface of the metal foil of the film-shaped printed wiring substrate 1 by corona charging. The processing step in the charging device 10 corresponds to the above-described first step. That is, in the charging device 10, for example, two
In the ion shower space formed by applying a discharge power of 0 to 30 W / m ² / min, the film-shaped printed wiring substrate 1
, It is possible to charge the metal layer 3 with a sufficient amount of charge.

The electrophotographic apparatus 11 converts an original image corresponding to an etching mask pattern prepared in advance into a toner image 5 and transfers the toner image 5 to the surface of the metal layer 3 of the printed wiring board 1. It is used, one example of which is shown in FIG.

As shown in FIG. 1, the electrophotographic apparatus 11 includes a drum type photoreceptor 21, a charging unit 22, an exposure unit 23, a development unit 24, and a transfer unit 25 which rotate in the direction of the arrow. . The operation of the electrophotographic apparatus 11 is as follows.

First, in the charging section 22, corona charging is applied to the entire surface of the drum type photosensitive member 21 made of a photoconductive semiconductor.

Next, in the exposure section 23, exposure corresponding to the original image (etching mask pattern) is performed on the surface of the drum type photosensitive member 21 charged in the previous step. As described above, this exposure can be performed by either a projection exposure method using an original sheet or a beam scanning exposure method using digital image information. At this time, on the surface of the photoreceptor 21, the portion exposed to light becomes conductive and the charge is reduced, whereas the charge of the portion not exposed to light is left as it is. A latent image is formed.

Next, in the developing section 24, the frictionally charged toner 24a is brought into contact with the surface of the drum type photosensitive member 21 on which the electrostatic latent image is formed. At this time, the toner 24a
Are charged in a polarity opposite to the charge on the photoconductor 21. Therefore, the toner 24 a selectively adheres only to the area where the electric charge exists on the photoconductor 21, whereby the development is performed, and a toner image corresponding to the etching mask pattern is generated on the surface of the photoconductor 21. Is done.

Finally, in the transfer section 25, the photosensitive member 2
1 is brought into contact with the surface of the metal layer 3 of the printed circuit board 1 charged to the same polarity as the latent image, that is, the polarity opposite to that of the toner, whereby the toner image on the photoreceptor 21 is electrostatically charged. The toner image is moved toward the substrate 1 by the attraction, and the transfer of the toner image is completed. The process leading to the transfer in the electrophotographic apparatus 11 corresponds to the above-described second process.

The heat fixing device 12 is heated at a temperature at which the resin, which is the main component of the toner, can be heated and melted with respect to the film-shaped printed wiring substrate 1 sent out from the electrophotographic device 11 at a temperature of 150 ° C. for 10 minutes. Then, the toner image is fixed on the surface of the metal foil of the film-shaped printed wiring substrate 1 under the heating condition. The step of fixing the toner image corresponds to the above-described third step.

As described above, the surface activation by the charging device 10, the electrostatic transfer by the electrophotographic device 11, and the heat fixing device 1
2 is sequentially performed on the film-shaped printed wiring substrate 1 as a series of processes.

In this series of processes, the activation of the surface by the charging device 10 can minimize the occurrence of defects such as pinholes in the circuit pattern during electrostatic transfer in the electrophotographic device 11, and can be substantially reduced. Defects can be eliminated. Further, when the toner image is fixed by the heat fixing device 12, even if a defect such as a pinhole slightly remains in the circuit pattern, the defect can be completely erased.

In addition, such a continuous production facility has the following effects. That is, when the film-shaped printed wiring base material 1 is fed in a continuous line as shown in FIG. 2, (1) the distance between the first step and the first step can be reduced, and (2) the film-shaped printed wiring base material 1 Since a tensile force can be added to the film, the occurrence of wrinkles and undulations on the film-shaped printed wiring substrate 1 in the area of the electrophotographic apparatus can be prevented, and a highly accurate pattern can be formed.
(3) Since the feed mechanism is provided outside the area of the electrophotographic apparatus, it is possible to simultaneously form a pattern on both surfaces of the film-shaped printed wiring substrate 1 and to manufacture a double-sided printed wiring board with high positional accuracy. A special effect is obtained.

Next, FIG. 4 shows an apparatus for carrying out another embodiment of the method of the present invention (hereinafter, referred to as a second embodiment). The feature of the second embodiment is that a mechanical roughening device 30 mechanically roughens the metal foil of the film-shaped printed wiring substrate 1 before the electrostatic transfer is performed by the electrophotographic device 11. To perform surface roughening treatment.

In other words, in the second embodiment, instead of the surface treatment of the metal foil by corona charging in the first embodiment, mechanical processing such as buffing, polishing cloth processing, brush polishing and the like is used. The surface is roughened. In the first embodiment, the charging method increases the transfer energy of the toner particles to improve the reliability of the toner deposition on the substrate, whereas the present method employs an anchor by mechanical surface roughening. The purpose of the present invention is to suppress the occurrence of the above-mentioned defects as much as possible by generating the effect or improving the toner adhesion by removing the surface oxide film.

If the surface roughening by the present method is excessively performed, defects in the toner deposition pattern increase.
It may be preferable to carry out at 0 μmRs or less.

Next, FIG. 5 shows an apparatus for carrying out still another embodiment of the method of the present invention (hereinafter, referred to as a third embodiment). The feature of the third embodiment is that before the electrostatic transfer is performed by the electrophotographic apparatus 11, the chemical roughening device 40 mechanically applies the metal foil of the film-shaped printed wiring substrate 1 to the metal foil. To perform surface roughening treatment.

That is, in the third embodiment, instead of the surface treatment of the metal foil by corona charging in the first embodiment, a chemical surface roughening treatment such as electrolytic polishing or chemical polishing is performed. Is adopted. In the first embodiment, the charging process increases the transfer energy of the toner particles to improve the reliability of the toner deposition on the base material, whereas the present method removes irregularities on the metal surface. It is intended to suppress the occurrence of the above defects as much as possible by smoothing and increasing the contact force by increasing the contact area of the toner particles.

If the material of the metal foil is aluminum as in the first embodiment, in the case of electrolytic polishing, for example, in a bath of 20% sodium carbonate + 5% sodium phosphate,
The treatment may be performed at a current density of 3 to 6 A / dm ² and a bath temperature of 90 ° C. for 5 minutes. In the case of chemical polishing, phosphoric acid 11
The treatment may be performed for 5 minutes in a bath of +50 ml of hydrogen peroxide solution.

When the material of the metal foil is copper, in the case of electrolytic polishing, in a bath of 76% phosphoric acid + 10% chromic acid,
The treatment may be performed at a current density of 30 to 50 A / dm ² , a bath temperature of 80 ° C., and 10 minutes. In the case of chemical polishing, the treatment may be performed in a mixed bath of nitric acid, sulfuric acid and hydrochloric acid.

Finally, the material of the toner used in each of the above embodiments will be described. In the first embodiment, as the toner used in the second step (step using an electrophotographic apparatus), a toner containing an ionomer resin as a main component can be used.

The toner containing the ionomer resin as a main component is kneaded with, for example, a wax made of low molecular weight polypropylene and a charge control material made of metal while applying heat.
It can be manufactured by stretching this into a sheet, cooling it and pulverizing it, and then attaching a fluidizing agent made of hydrophobically treated silica to the surface of this powder.

The ionomer resin has a side chain of a carboxylic acid group in the molecular chain of polyethylene, and a part of the carboxylic acid group is cross-linked between molecular chains by a metal cation as shown in FIG.
It has a structure as shown in The cross-linking by metal ions is characterized in that the bonding force is weakened by heat and becomes stronger when cooled, and has a stable thermal adhesiveness to metals and the like because it has a carboxylic acid group.

The feature of the ionomer resin is that it eliminates defects such as pinholes in the third step (step using a heat fixing device) or adheres the toner to the metal foil in the third embodiment. Brings good effect.

In the first, second, and third embodiments, the surface activation or surface roughening of the metal foil is performed as a pretreatment before the transfer of the toner image (the first embodiment). Although it has a configuration corresponding to the process), an apparatus for performing such pre-processing can be omitted as shown in FIG.

In the case where a configuration in which the pre-processing device can be omitted as shown in FIG. 7 can be adopted, the magnitude of the electrical rating of the transfer unit 25 which is a main part of the electrophotographic apparatus in FIG. Becomes

That is, if the amount of charge that can be given to the metal foil of the film-shaped printed wiring substrate 1 in the transfer portion 25 is sufficiently large, the surface activity of the metal foil is determined as a pretreatment before the transfer of the toner image. It is possible to suppress the occurrence of defects in the toner image at the time of transferring the toner image without performing surface roughening or surface roughening.

For example, it is assumed that the surface activation of the metal foil is performed as a pre-treatment before the transfer of the toner image, and thereby the occurrence of defects in the toner image can be suppressed to a desired degree during the transfer. The charge amount of the metal foil at this point is the sum of the residual value due to the pre-processing and the charge amount applied from the transfer unit 25. If the total charge amount can be obtained only by the transfer unit 25, the apparatus for performing the pretreatment can be omitted.

According to the first to third embodiments described above, at least the surface of the metal foil adhered on at least one surface of the film-like insulating substrate is activated by corona discharge or the like, or After surface roughening using a mechanical method such as paper polishing or a chemical method such as electrolytic polishing, a polymer powder (toner) is deposited in a desired circuit pattern shape by a known electrophotographic technique, and further at a temperature of about 150 ° C. An etching mask having a desired circuit pattern shape can be obtained in a process of heating the resin for 10 minutes to melt the resin, which is a main component of the toner, and fixing the resin on a metal foil, thereby having the following special effects. It is.

That is, in the present invention, since the etching mask pattern is formed by electrophotography, (1) 1
It is possible to manufacture a conductor circuit composed of a fine wire of 00 μm or less, (2) it can be manufactured with simple equipment and does not require large capital investment, and (3) the number of processing steps is small and the manufacturing cost is reduced. What you can do,
(4) There is no need for a negative film, and circuit patterns can be stored in the memory of the hard disk, so that drawing management can be performed efficiently. (5) Further, design changes such as partial circuit changes can be executed in a short time. (6) The pinhole is filled by melting the resin component in the toner,
(7) It is possible to form a highly reliable mask, (7) the heat treatment is performed in a short time, so that it can be applied to a substrate having poor heat resistance, and (8) there is no need to form a photosensitive layer. An excellent effect such as no generation of defects such as wrinkles can be obtained even with a substrate having poor mechanical strength.

[0067]

As is clear from the above description, according to the present invention, a highly reliable etching mask capable of forming a fine pattern can be formed in a simple process without requiring a large capital investment. Methods and apparatus can be provided.

[Brief description of the drawings]

FIG. 1 is a state transition diagram used for explaining a method according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram schematically showing an apparatus for performing the method according to the first embodiment of the present invention.

FIG. 3 is a detailed explanatory view of an electrophotographic apparatus which is a main part of the apparatus for performing the method according to the first embodiment of the present invention.

FIG. 4 is a configuration diagram schematically showing an apparatus for performing a method according to a second embodiment of the present invention.

FIG. 5 is a configuration diagram schematically showing an apparatus for performing a method according to a third embodiment of the present invention.

FIG. 6 is a diagram showing a structure of an ionomer resin which is a main component of a toner suitable for carrying out the present invention.

FIG. 7 is a configuration diagram schematically showing an apparatus for performing a method according to a fourth embodiment of the present invention.

FIG. 8 is a state transition diagram used to describe a conventional method for forming a first etching mask.

FIG. 9 is a state transition diagram used to describe a conventional method for forming a second etching mask.

DESCRIPTION OF SYMBOLS 1 Printed wiring base material 2 Insulating layer 3 Metal foil 4 Surface treatment layer 5 Toner image 6 Etching mask 7 Sending roll 8 Winding roll 9 Feeding roller 10 Charging device 11 Electrophotographic device 12 Heat fixing device 13 Sending Roller 21 Drum type photoreceptor 22 Charging unit 23 Exposure unit 24 Developing unit 24a Toner 25 Transfer unit 30 Mechanical roughening device 40 Chemical roughening device

Claims (13)

[Claims] A step of preparing an original image corresponding to a pattern of an etching mask; a step of converting the original image into a toner image using electrophotography; and transferring the toner image to a surface of a metal to be etched. A method for forming an etching mask, comprising: 2. The method according to claim 1, further comprising a step of performing a pretreatment for promoting adhesion of a toner to the surface of the metal before the transfer. 3. The method according to claim 2, wherein the pretreatment is a surface activation treatment by corona discharge. 4. The method according to claim 2, wherein the pretreatment is a mechanical surface roughening treatment. 5. The method according to claim 2, wherein the pre-treatment is a chemical surface roughening treatment. 6. The method for forming an etching mask according to claim 1, wherein the metal is a metal foil of a printed circuit board. 7. A means for preparing an original image corresponding to a pattern of an etching mask; a means for converting the original image into a toner image using electrophotography; and transferring the toner image to a surface of a metal to be etched. Means for forming an etching mask. 8. The etching mask forming apparatus according to claim 7, further comprising means for performing a pretreatment for promoting adhesion of toner to the surface of the metal prior to the transfer. 9. The etching mask forming apparatus according to claim 7, wherein the pretreatment is a surface activation treatment by corona discharge. 10. The etching mask forming apparatus according to claim 7, wherein the pre-treatment is a mechanical surface roughening treatment. 11. The apparatus according to claim 7, wherein the pretreatment is a chemical surface roughening treatment. 12. An etching mask forming apparatus according to claim 7, wherein said metal is a metal foil of a printed circuit board. 13. The method or apparatus for forming an etching mask according to claim 1, wherein the toner contains an io-monomer resin as a main component.