JPH10151872A - Printing mask for particle-containing paste and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a pattern of paste having satisfactory shape on a surface of a material to be printed by providing grooves of a slightly smaller width than a diameter of a globular particle at a predetermined interval on an overall sidewall face of a pattern hole provided at a printing mask. SOLUTION: The printing mask 52 having printing pattern pores is slidably rubbed by a squeegee, a viscous material containing globular particles in a viscous fluid material is coated widely, and charged in the pores. Thereafter, the mask 52 is released, and the viscous material is transferred in a pattern shape corresponding to the pattern pores onto a surface of the material to be printed. In such a stencil printing, grooves 63 are provided on sidewalls of the pattern pores to ensure sliding of the viscous material charged in the pores and containing the particles and the sidewall of the pattern pores so that the viscous fluid material contained in the viscous material is stored in the grooves 63. Thus, function of lubricant is performed for the fluid material. Cross sectional shape of the groove 63 may be any of triangular, rectangular wave, sine wave, semicircular and elliptical shapes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing mask for particle-containing paste used when a viscous paste pattern is formed on the surface of a printing material using a stencil printing technique, and an apparatus for manufacturing the same.

[0002]

2. Description of the Related Art As a method of soldering a board and a component in a mounting process of an electronic board, a soldering iron is used to start soldering, and then a dipping method in which a joint is immersed in a molten solder bath. A reflow method in which a joining surface is passed while immersing the joining surface has been put to practical use.
At present, the reflow method, which is an application of printing technology, has become mainstream.

[0003] Cream solder is obtained by kneading a fine powder of solder with a flux. The solder is printed on a pad which is a joint on the electronic substrate side, and a lead of an electronic component to be soldered is mounted thereon. Using the viscosity of the cream solder, the components are transported while being held on the board and passed through a heating furnace called a reflow furnace, at which point the cream solder is melted and the pads on the board and the component leads are soldered. .

In such a reflow process, a very important thing is a print mask used for printing cream solder.

The general printing method can be roughly classified into a transfer type represented by letterpress, flat plate, intaglio and the like, and a copy type represented by copy, stencil and silk screen. The printing mask used for printing cream solder, which is emphasized in securing, is a copy-type printing mask.

In this copy printing, as a printing method using a stencil printing plate, there are an etching mask, an additive mask, a YAG laser mask and the like, and further, there is an excimer laser mask using a plastic plate for the printing plate.

As described above, all of these masks are designed to secure the amount of paste to be printed, but the printing area is often limited by the requirements of the printing side. The thickness of the mask is important for securing the amount.

Therefore, a printing mask plate having a designated thickness is used.

As described above, since a certain thickness is required for the mask plate in order to secure the printing amount of the paste, as the thickness of the mask plate becomes larger or the opening area becomes smaller, the inner wall of the printing pattern hole becomes smaller. The effect of the state on the escapability increases, and the escapability deteriorates.

Furthermore, the paste removability is greatly affected by the unevenness of the cross-sectional shape of the printing pattern hole, the surface roughness of the inner wall, the surface energy (wetting property, water repellency) of the inner wall, etc., which vary depending on the mask plate manufacturing method.

Therefore, first, the progress of a printing mask manufacturing technique relating to the unevenness of the cross section of the printing pattern hole and the surface roughness of the inner wall will be described.

FIG. 1 to FIG. 4 are conceptual diagrams showing the manufacturing method of the etching mask in cross section, and FIG. 5 is a conceptual diagram of the etching mask opened as a result.

In FIG. 1, reference numeral 1 denotes a metal plate used as a plate material, which is mostly stainless steel SUS304.

In addition to this, roll habit removal, hairline processing,
After degreasing or the like, a photoresist 2 is applied, and a photo film 3 is adhered from both sides as shown in FIG.

When the photoresist is washed and developed after a predetermined aging time, masking of the required design by the coating film of the photoresist 2 can be performed as shown in FIG.
On the other hand, a photoresist stripping portion 5 is formed.

After inspection and treatment of pinholes, damage, dirt, etc. of the masking, the plate material 1 is not masked by the etching solution 6 such as ferric chloride after the treatment with an etching shower device as shown in FIG. The portion is melted, and a print pattern hole as shown in FIG. 5 is formed in a few minutes. Thereafter, the photoresist is peeled off and a neutralization process is performed.

In the etching mask manufactured in this manner, the projection 7 at the center of the printing pattern hole as shown in FIG. 5 is formed, and the surface roughness of the inner wall surface of the printing pattern hole is rough. Poor print quality is impaired due to poor printability.

The additive mask is manufactured by a method also called an electroforming method. FIGS. 6 to 9 are conceptual views showing the additive mask manufacturing method in cross section, and FIG. 10 is a conceptual view of a printing pattern hole. .

In FIG. 6, a dry film 9 of a photosensitive resin is laminated on the surface of a substrate 8 to be an electrode at the time of plating.
0, a dry film 9 is further laminated thereon to add thickness.

Next, a photomask 11 patterned as shown in FIG. 7 is brought into close contact with the dry film 9, exposed by a light source 12 for exposure, developed after a certain aging time, and cured as shown in FIG. Then, the female mold 13 having a printed pattern hole shape formed of the insolubilized dry film remains on the substrate 8.

When the substrate 8 with the female mold 13 is placed in an electrolytic nickel plating solution as shown in FIG. 9 and the cathode side is energized, nickel precipitates on the surface of the substrate 8 and the dry film female mold 13 is removed. The deposited nickel layer 14 gradually grows and becomes thicker around the periphery.

When the deposited nickel layer 14 reaches a predetermined thickness, the deposited nickel layer 14 is lifted up from the plating solution, neutralized, peeled off the substrate 8 from the substrate 8, and the dry film female mold 13 is removed. Such a printed pattern hole can be obtained.

The shape of the inner wall of the printing pattern hole is relatively flat reflecting the shape of the female die 13 of the dry film,
Since the printing quality is better than the etching mask, it is suitable for fine printing.

However, at times, a band-like portion having a rough surface or a step 15 as shown in FIG. 10 may be formed on the inner wall surface corresponding to the portion of the photosensitive adhesive 10 to which the dry film is attached. is there.

Further, since the photosensitive adhesive 10 has a slightly low light transmittance, it is difficult to extend the exposure time to sufficiently expose the bottom of the dry film 9 on the substrate side or to expose the photosensitive adhesive 10 to strong light. There is a case where unevenness 16 is generated on the inner wall surface of FIG.

The irregularities 16 are formed on the inner wall on the light source side with the photosensitive adhesive 10 as a boundary.
It is said to be an "attack phenomenon" or "break", and is a shape that impairs printability.

The YAG laser mask is a printing mask of a relatively new manufacturing method. FIGS. 11 to 13 are conceptual views showing the manufacturing method of the YAG laser mask in cross section, and FIG. 14 is a conceptual view of the YAG laser mask opened as a result. FIG.

In FIG. 11, reference numeral 17 denotes a metal plate used as a plate material, which is mostly stainless steel SUS304. This SUS304 is almost the same as the metal plate 1 used for the etching mask. However, while the etching mask used is one that has been cold rolled several times or more, the YAG laser requires a lot of rolling times. do not do.

After removing the roll habit and the like,
Although the metal plate 17 is heated and melted by the YAG laser beam 18, the metal plate 17 cannot be cut by this alone, so the metal 20 is removed by the assist gas 19.

FIG. 12 shows the cutting procedure. Piping the first through hole 21 is called piercing, but the processing range at this time tends to be wide, and when piercing is performed on the planned cutting line, the processed shape protrudes only outside that portion, so as shown in the figure. Then, the piercing is performed at the portion to be removed, and then the cutting process is performed so as to join the line to be cut.

In this cutting by the YAG laser, FIG.
As shown in the figure, the dissolved dross 22a adheres to the cutting edge and cannot be used as a print mask as it is,
The dross 22a is removed by polishing the surface.

At this time, the burrs 22 in the print pattern holes
When the occurrence of b is remarkable, it also becomes a factor that hinders the removability of the paste at the time of printing. Therefore, the burrs 22b may be further removed by electrolytic polishing.

As shown in FIG. 14, the completed printing pattern holes have severe irregularities 23 on the inner wall surface, and the printing quality is higher than the etching mask but lower than the additive mask.

Attempts have been made to produce a similar print mask with a CO ₂ laser at one time. However, since the thermal effect is more extensive than that of a YAG laser, the unevenness of the inner wall surface is more severe, and sufficient print quality as a print mask is obtained. It could not be realized and did not spread.

As described above, the mask for stencil printing is also called a "metal mask" because the stencil material is a metal plate except for a silk screen, and is important in stencil printing of a paste. Printing is required. Excimer laser using a plastic plate as a plate material as a new mask to solve problems such as poor adhesion with metal masks, limitations of fine processing, long delivery times and high costs due to manufacturing methods and materials. (See JP-A-7-81027).

This mask is called an “excimer laser mask” when focusing on the manufacturing method, and is called a “plastic mask” when focusing on the material of the plate. Hereinafter, the excimer laser mask is referred to as “excimer laser mask”.
8 is a conceptual diagram showing the manufacturing method of the excimer laser mask in cross section, and FIG. 19 is a conceptual diagram of the excimer laser mask opened as a result.

In FIG. 15, reference numeral 24 denotes a range of the beam light of the excimer laser to be irradiated. In contrast to a linear YAG laser or CO ₂ laser, the cross section of the excimer laser beam light 24 is a plane. After obtaining the energy density which can be processed by condensing the light by using the mask 26, the plastic plate 27 which is the mask plate material is opened.

FIG. 16 is a conceptual diagram of the principle of processing a plastic by an excimer laser. The plastic, which is a polymer, is formed by solidifying an infinite number of atoms 28 by covalent bonds.
When is irradiated with a certain energy or more, electrons stable in the base orbit are excited and move away from the shared orbit to the upper orbit.

Therefore, as shown in FIG. 17, the covalent bond is not established, and the cleaved atoms 30 are scattered at a high speed. As a result, the plastic surface in the laser beam irradiation range is dug.

The digging amount per laser beam irradiation is 1
It is often less than μm, but digging to any depth is possible by repeating this process. If digging is done more than the thickness of the plastic plate of the mask material, it becomes a through hole.

Such processing using an excimer laser is called ablation processing. At that time, the temperature of the scattered atoms is as high as 6,000 degrees Celsius, but since the series of mechanisms is completed in a short time of 20 nanoseconds, there is not enough room to conduct heat to adjacent atoms. Also say.

As described above, the excimer laser ablation processing can be easily performed with extremely fine planar processing at the wavelength level and the atomic level without being substantially affected by thermal, chemical and mechanical effects.

FIG. 18 shows the state of processing, and FIG. 19 shows the shape of the resulting print pattern hole. The processing state is very good as the inner wall surface of 31, and the print quality is as described above. Etching mask, additive mask,
Outperforms YAG laser masks.

FIGS. 20 to 32 are cross-sectional views of defective shapes having poor removability of paste generated by such a printing mask manufacturing method, and explanatory diagrams of the causes of the generation.

FIG. 20 shows a defective shape in which the edges of the printed pattern holes are rounded. Excessive time was taken to remove the burrs and burrs by the punch-pressing side of the punch press mask that had been produced for a while, or by electrolytic polishing. Occurs in some cases. As compared with a mask having a good edge, the filling property of the paste is inferior and the removability is poor.

FIG. 21 shows a defective shape having burrs on the upper or lower edge of the printing pattern hole, which is generated on both the front and back surfaces by the dross polishing of the YAG laser mask and on the die side of the punch press mask. Again, the shape deteriorates the removability.

FIG. 22 shows a defective shape called "jagging" in which irregular concave portions are formed at the ridges of the edges of the print pattern holes. As shown in FIG. The mask 6 causes the photoresist 2 for masking to be partially peeled off from the metal plate 1 for printing, and may occur on both sides.

In addition, as shown in FIG. 24, the periphery of the fine print pattern hole of the additive mask may be protected by a masking 32 for limiting an etching range, and a half etching process may be performed to reduce the thickness of the mask by etching.

If the filling of the resin 33 for protecting the inner wall of the printing pattern hole performed at this time is insufficient, as shown in FIG. 24, the etching liquid seeps into the gap generated between the inner wall and the resin, and the ridge line of the edge of the printing pattern hole. 34 is etched by the etchant and becomes jagged. This is also a cause of inferior paste filling and removability.

FIG. 25 shows a typical defective shape in an etching mask in which the central portion of the inner wall of the printing pattern hole has a convex shape. As shown in the manufacturing method of FIGS. 1 to 4, the masking is peeled off in the process of opening from the front and back of the metal plate 1 by etching, and the exposed metal plate 1 is dug into a pot bottom type having a deep exposed center and a shallow peripheral portion. To go.

For this reason, when the etching holes proceeding from both the front and back sides become continuous holes, a central convex portion 7 shown in FIGS. 5 and 25 is generated. This shape hinders the passage of the paste and hinders the removability. Further, since the inner wall surface is etched by etching, the surface roughness is rough, and the printing quality is further deteriorated.

Although the metal mask 7 is the etching mask that has been put into practical use the earliest, the printing quality is inferior to any of the YAG laser mask, the additive mask, and the excimer laser mask, and is not suitable for precise printing.

FIG. 26 shows a defective shape with excessive taper generated in the additive mask. The manufacturing method of the additive mask is shown in FIGS. 6 to 9 described above. In particular, in the exposure step shown in FIG. 7, when a scattered light source 35 as shown in FIG. It has a cross-sectional shape.

If the inner wall of the print pattern hole of the print mask is vertical, the printability is determined by the tacking force of the paste on the printing material and the inner wall of the mask which tries to peel off the paste from the surface of the printing material as the plate separates. It is determined by the shear stress between them.

However, as the inner wall is tapered, the tacking force between the inner wall and the paste increases, which opposes the tacking force between the surface of the printing material and the paste, thereby deteriorating the removability.

FIG. 27 is a conceptual diagram of exposure by the scattering light source 35. Light incident from the transparent pattern portion of the photomask 11 is transmitted to the dry film 9 by the light source 3
The part 36 to which no light reaches 5 and the part 3 to which some light reaches
7. The difference between the portion 38 to which all light reaches and the exposure condition is generated.

In particular, in a portion 37 to which some light reaches, the amount of light near the portion 36 to which no light reaches at all is small, and in a portion near the portion 38 to which all light reaches, a large amount of light is exposed. Is continuously changing.

If the dry film 9 exposed under such a scattered light source has a high exposure sensitivity, the dry film 9 has a hardened and insolubilized shape including the range of the portion 37 to which light reaches as shown in FIG. 29, the shape does not include the range of the portion 37 to which light partially reaches as shown in FIG.

To cope with such an excessively tapered shape, in order to perform exposure with parallel light, a honeycomb-shaped shielding plate is placed in the middle of the optical path to block only oblique light with the inner wall surface of the honeycomb, or the ultraviolet light of the light source. By installing a lamp at the focal point of a parabolic mirror and using the parallel reflected light,
At present, the excessive taper shape has been reduced.

FIG. 30 shows a characteristic of the additive mask.
This is a defect shape in which a step 15 occurs on the inner wall of the printing pattern hole.

In the above-described additive mask manufacturing method, as shown in FIG.
In many cases, the photosensitive adhesive 10 is laminated in accordance with the thickness of the mask.
0 or a step 15 as shown in FIG. 30 occurs. This shape is also a defective shape that hinders the removability of the paste.

On the other hand, a dry film thicker than before has been provided, and it is becoming easier to avoid using the photosensitive adhesive 10.

FIG. 31 is also specific to the additive mask.
"Overexposure phenomenon", "Attack phenomenon", "Kiage"
57 ', etc., and the photosensitive adhesive 10
This is a problem caused by laminating the dry film 9.

When exposing the laminated dry film, the exposure is performed as shown in FIG. 7 with the top and bottom turned upside down as shown in FIG. Due to poor transmittance, there is a possibility that the bottom of the dry film is not sufficiently exposed.

As a countermeasure, a long time exposure or a large light amount exposure is performed. If the exposure is excessive, a shadow portion which is shielded by a photomask is exposed by halation in the dry film, and the inner wall surface has irregularities 16. become. The unevenness 16 is also a factor that hinders the removability of the paste.

FIG. 32 shows a problem that occurs in the etching mask. Description of the manufacturing method As shown in FIG. 2, two photo-films 3 are used for exposing the etching mask. Usually, the photo-films are provided with registration marks called registration marks, and thereby, the upper and lower films are used. Adjust the position so that they do not shift, and attach them together in a bag.

If the wafer is manufactured with the misalignment, the shape of the inclined printed pattern hole is generated in the etching mask. This inconvenience not only deteriorates the removability of the paste, but also varies the print quality depending on the moving direction of the squeegee.

FIG. 33 is a conceptual diagram showing the releasability of the paste when the pattern hole cross-sectional shape of the print mask is good, and FIG. 34 is a conceptual diagram showing the releasability when the pattern hole cross-sectional shape is poor.

FIG. 35 is a conceptual diagram showing a defective shape due to a difference in paste removability in printing a slit hole shape.

The defect "no paste" shown in FIG. 35 means that the paste was not removed from the inside of the print pattern hole and was not printed on the surface of the printing material. "Lack of paste"
In the figure, a portion of the print pattern hole having poor removability is partially clogged.

In the “turning-up”, the shear stress due to poor removability of the mask side when the plate is released and the tacking force to the surface of the printing material pull the paste, and the film is partially peeled off from the printing material surface once. The paste then falls on the surface of the printing substrate, and often shifts from the position where printing is desired.

The word "tsu" has many expressions such as "saddle shape", "saddle", and "stringing". However, when the print pattern hole portion with poor removability pulls the paste against the surface of the printing material when the plate is separated. Due to the viscosity and spinnability, the shape becomes defective as shown in the figure.

"Bridge" is a type in which the degree of "one" is more intense. When the adjacent pattern is in contact with the defective paste shape, especially when the paste is used for forming an electric circuit, it is called "short". Sometimes called.

The above description has been given of the technique of forming a printed pattern hole of a mask from the viewpoint of print quality. It has been found that it also depends on the wettability with respect to the paste and the water repellency.

Therefore, as shown in FIG. 36, a print mask having a Teflon coating layer 44 on the inner wall of a print pattern hole or a print mask plate manufactured by an additive method as shown in FIG. A printing mask by a “composite plating method” has been proposed in which a part of the Teflon fine particles 46 is dispersed and exposed on the plating surface as shown in FIG. Was.

Although these printing masks have not been widely used due to their high cost, the removability has been greatly improved.

However, in addition to the improvement of the sectional shape of the opening,
Even if the wettability and water repellency of the inner wall surface with respect to the paste are improved, when the printed pattern hole shape is fine and the slit shape is 47 as shown in FIG. 39, the paste is clogged at the corners at both ends of the hole. It's easy to do.

This is because the ratio of the inner wall area of the corner to the tacking area between the surface of the printing material and the paste is large, and the shear stress for peeling off the paste at the time of separation of the plate exerts the greatest effect at the corner. It is.

From this, it can be seen that shear stress has not been completely removed by the water repellent processing of the inner wall of the print pattern hole of the current print mask.

FIGS. 40 and 41 are conceptual views of a plane and a cross section in the same printing, showing an example of the tendency of the paste to be clogged. When printing the paste 50 containing the spherical particles by forming the printing pattern holes of the round shape 48, the square 49 and the slit shape 47 on the printing mask, the squeegee 51 is directed downward from above in FIG. 40, and from left to right in FIG. When squeezing is performed on paste 50, paste 50
At 0, clogging tends to occur on the lower pattern hole side wall, and in FIG. 41, on the right pattern hole side wall.

This depends on the squeezing direction.
The squeezing direction is from bottom to top in FIG. 42 and from right to left in FIG. 43. In all cases, the paste 50 is likely to be clogged on the pattern hole side wall in the forward direction of the squeegee.

FIGS. 44 to 47 show the mechanism of filling the paste into the printing pattern holes described above.

In FIG. 44, when the squeegee squeezes the paste placed on the print mask to the right, the paste pressed from behind while adhering to the mask plate while rolling as shown by the arrow in FIG. When moving forward to the right and reaching the print pattern holes, FIGS.
As shown in FIG. 7, the paste is sequentially filled from the near side of the opening.

However, when actually observed, the filling mechanism was as shown in FIGS.

In FIGS. 48 to 51, when the squeegee is squeezed to the right in the drawing, the paste placed on the print mask slips on the print mask plate while rolling.

In FIG. 48, the paste reaches just before the opening.
According to the conventional description, the paste should be filled in the printed pattern holes after that, but actually, the paste does not fill the openings even if the paste crosses over the openings of the pattern holes.

In FIG. 49, when the front end of the paste reaches the opening edge on the front side in the traveling direction of the squeegee and further slips forward, the bottom of the paste is caught by the front side edge and is scraped off from below. Then the filling starts.

The paste filled in the opening causes the bottom of the paste passing through the upper portion of the pattern hole to stay therein, and the held paste is further pushed by the paste coming from the rear, so that the paste is moved downward. The opening is filled into the opening so as to expand.

Thus, by the time the squeegee passes over the print pattern hole, the paste is completely filled in the space in the opening.

Further, when the state of the filled paste was observed, as shown in FIG. 52, a coarse particle density portion 50 was found in the space in the opening on the rear side with respect to the traveling direction of the squeegee.
On the other hand, there is a portion 50b having a high particle density at a portion in contact with the side wall on the front side with respect to the traveling direction of the squeegee, and a difference occurs in the particle distribution.

The dense portion of the particle distribution coincides with the distribution of the spherical solid-containing paste clogging the side wall of the pattern hole on the front side in the traveling direction of the squeegee in FIGS. 40 and 41. There is a correlation between the release of the paste when the plate is released.

This correlation is explained by the surface energy related to wettability. A paste containing solid particles retains the properties of the paste by filling the space between the particles with a viscous liquid, but if the ratio of viscous liquid to solid particles is high, the viscosity of the paste as a whole decreases and the paste becomes fluid. It will be easier.

Conversely, when the ratio of the viscous liquid decreases, the viscosity increases, and the tendency to maintain the shape increases.

This is because the viscous liquid between the solid particles functions as a lubricant between the particles at a certain content or more, but conversely, at a certain content or less, the surface energy of the solid particles and the viscous liquid is reduced. Are wetted by each other and attracted by the surface tension of the viscous liquid.
The solid particles are restrained from each other by the viscous liquid and are difficult to move.

Since this mechanism works not only between the solid particles but also between the solid particles and the side wall of the printed pattern hole, the density of the low solid particles and the ratio of the high viscous liquid filled in the space in the opening on the rear side with respect to the traveling direction of the squeegee. The paste is fluid and slippery also on the side walls, and as a result becomes a part with good removability.

Conversely, the paste having a high solid particle density and a low viscosity liquid ratio which is in contact with the side wall of the opening on the front side in the direction of travel of the squeegee is non-flowable and hard to slip on the side wall, and as a result, the part having poor removability is obtained.

Until now, poor removability due to the inner wall shape of the printed pattern hole, poor releasability due to the surface roughness of the inner wall surface, poor releasability due to the lubricity of the inner wall surface, etc. Countermeasures have been taken, but there is no effective countermeasure against the variation in the removability of the paste containing solid particles, which correlates with the squeezing direction. It has been demanded.

[0098]

As described above, in stencil printing using a stencil, various measures have been taken to ensure the removability, which has been a problem in the past, but there is still a correlation in the squeezing direction. There is no effective countermeasure against the occurrence of clogging, and an immediate response is desired.

Accordingly, an object of the present invention is to provide a printing mask for a paste containing particles, which hardly causes clogging related to the squeezing direction as described above, and an apparatus for manufacturing the same.

[0100]

According to a first aspect of the present invention, there is provided a printing mask having a pattern hole for printing.
The mask placed on the surface of the printing material is rubbed with a squeegee to spread a viscous fluid containing spherical particles in the viscous fluid, thereby filling the pattern holes with the viscous material. By separating the printing mask from the printing plate, in the printing mask for particle-containing paste used when transferring the viscous material to the surface of the printing material in a pattern shape corresponding to the pattern holes, the pattern holes provided in the printing mask are provided. Grooves having a width slightly smaller than the diameter of the spherical particles are provided at predetermined intervals on the entire side wall of the print mask, and the grooves extend in the thickness direction of the print mask.

That is, a groove is provided in the side wall of the pattern hole so as to ensure the slip between the viscous material containing the spherical particles filled in the pattern hole and the side wall of the pattern hole, and the groove is included in the viscous material. The viscous fluid to be collected is collected. The viscous fluid functions as a lubricant.

The invention according to claim 2 is characterized in that the cross-sectional shape of the groove is any one of a triangular shape, a rectangular wave shape, a sine wave shape, a semicircular shape, and an elliptical shape.

According to a third aspect of the present invention, there is provided a laser source for emitting an excimer laser beam, and an aperture having a side wall formed in a cross-sectional shape of the groove to shape the excimer laser beam into a predetermined shape. Or, a shaped excimer laser having a shaped reflecting surface formed around the reflecting surface in a cross-sectional shape of the groove, and shaping and reflecting the excimer laser light into a predetermined shape. Light is irradiated to the mask material to form a pattern hole for printing.

That is, when forming a mask having a groove on the side wall of the pattern hole, the excimer laser light is shaped into the shape of the pattern hole by an aperture or a mirror, and the shaped hole of the aperture or the shaped reflection surface of the mirror. A groove is formed in the groove, and the groove is formed simultaneously with the formation of the pattern hole.

[0105]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is more useful for fine printing, which has been difficult with conventional printing masks. It is hardly familiar with poor etching masks and YAG laser masks. Therefore, an embodiment of the present invention in an additive mask and an excimer laser mask will be described below.

In the method of forming the pattern hole shape of the print mask according to the present invention by the additive manufacturing method,
7 and 57 are exposure, FIGS. 8 and 58 are development, FIGS. 9 and 5
9 is a schematic configuration of a plating step.

In the exposure process shown in FIGS. 7 and 57, a photosensitive dry film 9 is laminated to a required thickness on a substrate 8 serving as an electrode substrate for electrolytic plating, and a design to be formed on the surface to determine an exposure shape. A photomask 11 designed to be divided into a transparent part and a light-shielding part is adhered by vacuum suction or the like, and a parallel ultraviolet light source 1 such as a high-pressure mercury lamp above
When the exposure is performed by the method 2, a latent image according to the design of the photomask 11 is obtained on the dry film 9.

At this time, in order to form a groove according to the present invention on the side wall of the pattern hole of the print mask, an uneven pattern 64 for forming the groove shape is used as a design of the photomask 11.

Further, in the developing process shown in FIGS. 8 and 58, when the latent image is visualized by performing a predetermined development with the photosensitive resin developer 65, the plated female mold 66 of the printed pattern hole according to the present invention is formed on the substrate 8. Is obtained.

In the plating process shown in FIGS. 9 and 59, the substrate 8 with the plating female die 66 is connected to the negative side of the power source 67 for electrolytic plating, and the nickel anode 68 for electroforming is connected to one positive side. When both are immersed in the electrolytic plating solution 45 and energized and subjected to a plating bath for a certain period of time and plated to a required thickness, a metal for a printing metal mask having a groove shape of a printing pattern according to the present invention is formed by an additive manufacturing method. A plate is obtained.

Then, the metal plate is peeled off from the substrate, and the plating female die 66 is dissolved and removed, and then joined to a printing frame via a polyester or nylon tensioning gauze film to form a printing mask. Completed as

On the other hand, the following is a method for forming the pattern hole shape of the print mask according to the present invention using an excimer laser mask. FIG. 56 shows a schematic configuration of an apparatus for forming a grooved excimer laser mask according to the present invention. In the figure, an excimer laser generator 56 that emits excimer laser light (hereinafter, simply referred to as laser light), a prism or a mirror 57 (57a, 57b, 57a, 57b, 57) that changes the optical path of the laser emitted from the excimer laser generator 56 is shown. 57
c), a beam adjuster 58 having a homogenizer for equalizing the intensity distribution of the laser beam, and a beam expander or beam compressor for reducing / enlarging the major and minor dimensions of the laser beam, and forming the laser beam into a predetermined shape pattern A beam forming unit 59 of a light blocking aperture or a reflecting mirror,
A condenser lens 60 for condensing a laser beam, a stage 61 for holding a plastic plate of a mask material and moving it in the XYZ axis directions, and a control unit 62 for controlling the positioning of the aperture stage and controlling the excimer laser generator 56. And a camera 63 for an observation optical system.

FIG. 60 is a view showing a state in which the laser beam shaped by the beam forming portion 59 of the light shielding aperture or the reflecting mirror in FIG. 56 is applied to the plastic plate of the mask material.

The beam forming section 59 is provided with a plurality of shaping holes 69 corresponding to the pattern holes. Needless to say, one shaping hole may be provided, and the shaping hole is appropriately set by a pattern.

On the inner peripheral side wall of the shaping hole 69, a groove having a reciprocal magnification of the reduction ratio of the condenser lens 60 is provided. Accordingly, a groove 53 is also formed in the pattern hole of the mask formed by the beam forming portion 59 as shown in FIG.

The width of the groove 53 is set to be slightly smaller than the particle diameter contained in the paste filled in the putter holes.

In such a configuration, the energy intensity distribution of the cross section of the laser beam emitted from the excimer laser generator 56 is strong at the center and weak at the periphery, and is uneven in distribution. When the non-uniformity adversely affects the processing, the homogenizer of the beam adjusting unit 58 may achieve uniformity.

The sectional shape of the emitted laser light is
In many cases, the shape is a rectangle with a slightly rounded corner, and if this shape has an adverse effect on the processing, the long and short diameters of the laser beam are reduced by the beam compressor of the beam adjusting unit 58 or enlarged by the beam expander. To adjust the required beam.

Thereafter, the prism or mirror 57 (57
The laser light whose optical path has been adjusted so as to be perpendicularly incident on the mask 59 by a, 57b, 57c) is shaped by a light-blocking aperture or a beam forming unit 59 of a reflection mirror, and projected by a condenser lens 60.

The energy of the laser beam projected in this manner is increased per unit area, and the laser beam can exceed the energy density required for ablation processing unique to each material. Is formed.

When the pattern holes are formed in the mask, the control unit 62 performs positioning of the stage 61 with the beam forming unit 59 of the light-shielding aperture or the reflecting mirror.
The next pattern hole is processed.

In the present invention, a groove is provided on the side wall of the pattern hole. However, since the adjacent space between the grooves is very small, if the pattern of the aperture or mirror of the forming portion 59 and the processing shape of the mask are the same size. The formation of the aperture or mirror of the forming section 59 is difficult and costly.

However, as described above, since this device is reduced and projected by the condenser lens 60, the pattern formed on the beam forming portion 59 of the light shielding aperture or the reflecting mirror may be larger by the reciprocal multiple of the reduction ratio. Since the manufacturing cost of the aperture and the mirror can be reduced, the manufacturing cost of the print mask can also be reduced.

[0124] Excimer laser light is unlikely to cause ablation. If fine particles having a diameter corresponding to the width of the groove 53 are contained in the mask material, the mask base material is not shadowed by the fine particles. The groove 53 can be formed naturally without being processed.

In this manufacturing method, variations occur in the pitch and depth of the groove arrangement, but it is not necessary to provide the groove 53 in the shaping hole 69 depending on the application.

Next, the operation principle of the present invention will be described. Conventionally, the side wall of the printing mask and the filled particle-containing paste 5
The side wall surface is made as smooth as possible so as to prevent the paste from remaining in the pattern holes 70 when the printing mask is separated from the plate by reducing the shear stress of 0.

However, as a result of closely observing the clogged state of the paste and the manner in which the paste is filled in the pattern holes, the inventors of the present application have found the following.

That is, the paste which is clogged when the plate is separated has a strong tendency to remain on the side wall (hereinafter, referred to as a receiving side wall) on the side where the inner wall faces the sliding squeegee.
This tendency was closely related to the mechanism of filling the particle-containing paste 50 into the pattern holes.

Referring to FIGS. 48 to 51, a mechanism for filling the pattern holes 70 with the particle-containing paste 50 will be described. The arrows in the figure indicate the movement of the particle-containing paste 50.

48 to 51, a paste 50 containing solid particles which is pushed by a sliding squeegee 51 and moves.
, While rolling on the mask plate, slips and moves forward.

In FIG. 48, the paste reaches the pattern hole 70, but after that, even when the paste 50 crosses over the opening of the pattern hole 70, the paste is not filled into the opening. When the paste reaches the edge of the receiving side wall and further slips forward, the bottom of the paste is caught on the edge of the front side receiving wall 71, and the filling is started as if the paste 50 was scraped off from below with a canna.

The paste 50 filled in the opening of the pattern hole 70 stays at the bottom of the paste 50 passing through the upper portion of the pattern hole 70, and the retained paste 50 is further reduced to the paste coming from behind. Pressed,
It is filled into the opening so as to swell downward.

By the time the squeegee passes over the print pattern hole, the paste is finally filled in the space in the opening.

The state of the filled paste is shown in FIG.
As shown in the figure, a portion 50a having a low solid particle density exists in the space in the opening on the rear side with respect to the traveling direction of the squeegee, while a portion contacting the side wall on the front side with respect to the traveling direction of the squeegee has a high density. And there is a difference in the particle distribution.

When the paste containing solid particles such as the paste is pressed against the receiving side wall, the density of the solid particles increases toward the receiving side 71a, but the liquid component in the paste easily opposes. Since it is possible to move to the side wall 71b, such a density distribution is generated by being squeezed out.

As a result, when the plate is separated, the side wall 71b having a large content ratio of the liquid component in the paste and a low particle density is obtained.
On the side, since this liquid component acts as a lubricant, shear stress with the side wall is reduced and the removability is improved.

On the other hand, in the portion where the solid particle density is high, the liquid component serving as the lubricant is small, and when the gap between the solid particles is reduced, the liquid component functioning as the lubricant is adversely affected by the wettability due to the surface energy. The solid particles attract each other and begin to restrain their movement.

As described above, the fluidity of the portion where the solid particle density is high is lost, and the gap between the solid particle and the inner wall surface is restrained and attracted to each other. As a result, clogging of solid particles frequently occurs in the portion of the receiving side wall 71a.

As described above, rather than the density of the solid particles in the paste caused by the filling mechanism, the opposite phenomenon that the removal is promoted on the one hand and the removal property is inhibited on the other hand occurs. .

Therefore, even if a high-density portion is generated in the solid particles dispersed in the paste, the liquid component in the paste acts as a lubricant, and the solid particles or the solid particles come into contact with the lumps having lost fluidity and meet the side wall 71. If interposed between the solid particles, clogging of the solid particles can be prevented.

Therefore, in the present invention, a groove slightly smaller than the particle size of the solid particles is formed on the side wall of the pattern hole so as to extend in the thickness direction of the print mask, and the liquid component in the paste contains the lubricant in the groove. And the side wall shape without unevenness is maintained in the direction in which the paste comes off.

As described above, the tendency of the paste to be clogged due to the direction of the squeegee can be prevented, and the paste containing the solid particles filled in the pattern holes 70 does not remain even if the plate releasing speed is increased. High quality and fine printing are possible.

In the above description, the cross-sectional shape of the peripheral portion of the groove 53 is described as being triangular. However, the present invention is not limited to this, and the rod shape, rectangular wave shape, sine wave shape shown in FIG. Shapes, semicircular shapes, elliptical shapes, etc. are possible.

In this case, in the case of a triangular shape, a bar shape, or the like, the corner portion may be rounded and chamfered.
It is desirable from the viewpoint of protecting the shape from abrasion and increasing durability.

[0145]

According to the present invention, since a groove having a width smaller than the solid particle diameter is provided on the side wall of the pattern hole, shear stress is reduced, and the paste containing solid particles remains in the pattern hole when the plate is separated. And the paste pattern having a good shape can be formed on the surface of the printing material.

When a mask having a groove on the side wall of the pattern hole is formed, the shape of the print pattern hole is formed by the photomask 11 in the additive mask and by the aperture in the excimer laser mask. By providing a groove forming pattern to the shaping shape of the photomask 11 or the aperture, the grooves can be formed simultaneously with the formation of the printing pattern holes, so that a high-quality printing mask can be manufactured at low cost. It is now possible.

[Brief description of the drawings]

FIG. 1 is a conceptual sectional view after a photoresist is applied in a method of manufacturing an etching mask.

FIG. 2 is a conceptual diagram of exposure in a method of manufacturing an etching mask.

FIG. 3 is a conceptual diagram of development in a method of manufacturing an etching mask.

FIG. 4 is a conceptual diagram of an etching process in a method of manufacturing an etching mask.

FIG. 5 is a conceptual diagram of an etching mask opened as a result of etching.

FIG. 6 is a conceptual diagram of lamination of a dry film in a method of manufacturing an additive mask.

FIG. 7 is a conceptual diagram of exposure in a manufacturing method of an additive mask.

FIG. 8 is a conceptual diagram of development in a method of manufacturing an additive mask.

FIG. 9 is a conceptual diagram of plating in a method of manufacturing an additive mask.

FIG. 10 is a conceptual diagram of an additive mask opened as a result of additive processing.

FIG. 11 is a conceptual diagram of a cutting method in a method of manufacturing a YAG laser mask.

FIG. 12 is a conceptual diagram showing a cutting procedure in a method of manufacturing a YAG laser mask.

FIG. 13 is a conceptual sectional view of a cut shape of a YAG laser mask.

FIG. 14 shows a Y opened as a result of a cutting process by a YAG laser.
This is the concept of the AG laser mask.

FIG. 15 is a conceptual diagram showing the processing principle of an excimer laser mask.

FIG. 16 is a conceptual diagram showing the principle of ablation processing using an excimer laser.

FIG. 17 is a conceptual diagram of a digging process by ablation.

FIG. 18 is a conceptual diagram of planar processing by an excimer laser.

FIG. 19 is a concept of an excimer laser mask opened as a result of excimer laser processing.

FIG. 20 shows a defective shape in which an edge portion of a printing pattern hole is rounded.

FIG. 21 shows a defective shape having burrs on the upper or lower edge of a printing pattern hole.

FIG. 22 shows a defective shape in which an edge of the upper surface or the lower surface of the print pattern hole is jagged.

FIG. 23 is a conceptual diagram of a cause of occurrence of a jagged defect in an etching mask.

FIG. 24 is a conceptual diagram of a cause of occurrence of a jagged defect in an additive mask.

FIG. 25 shows a defective shape in which the center of the inner wall of the printing pattern hole is convex.

FIG. 26 shows a defective shape in which the inner wall of the printing pattern hole becomes excessively tapered.

FIG. 27 is a conceptual diagram showing a mechanism of taper generation by a scattered light source.

FIG. 28 shows an exposure shape of a highly sensitive dry film by a scattering light source.

FIG. 29 shows an exposure shape of a dry film having low sensitivity by a scattering light source.

FIG. 30 shows a defective shape in which a step occurs on the inner wall of the print pattern hole.

FIG. 31 shows a defective shape due to an overexposure phenomenon generated on the inner wall of a printing pattern hole.

FIG. 32 shows a defective shape in which the printing pattern holes are inclined.

FIG. 33 is a view showing the shape of the paste that is removed when the pattern holes of the print mask are good.

FIG. 34 is a conceptual diagram of paste removability when a pattern hole of a print mask is defective.

FIG. 35 is a conceptual diagram of a defective shape of printing due to a slit hole.

FIG. 36 is a cross-sectional view of a printing mask having a Teflon layer on the inner wall of a printing pattern hole.

FIG. 37 is a conceptual diagram of a composite plating manufacturing method of Teflon fine particles and nickel.

FIG. 38 is an explanatory diagram of a state of Teflon by a composite plating method.

FIG. 39 is a conceptual diagram showing a state of paste clogging in the case of a slit hole.

FIG. 40 is a conceptual plan view showing the tendency of paste clogging due to squeezing from above.

FIG. 41 is a conceptual sectional view showing a tendency of clogging of a paste due to squeezing from the left.

FIG. 42 is a conceptual plan view showing the tendency of paste clogging due to squeezing from below.

FIG. 43 is a conceptual sectional view showing a tendency of paste clogging due to squeezing from the right.

FIG. 44 is a conceptual conceptual view showing a behavior of a paste on a mask plate surface in a conventional theory.

FIG. 45 is a cross-sectional conceptual view in a conventional theory showing a behavior of a paste reaching an end of a pattern hole.

FIG. 46 is a conceptual cross-sectional view illustrating a mechanism in a conventional theory at the moment when a pattern hole is filled.

FIG. 47 is a cross-sectional conceptual view according to the conventional theory when filling is completed.

FIG. 48 is a conceptual sectional view based on observation showing behavior of a paste on a mask plate surface.

FIG. 49 is a conceptual sectional view showing the behavior of a paste filled in a pattern hole.

FIG. 50 is a conceptual sectional view showing the behavior of the paste filled in the pattern holes.

FIG. 51 is a conceptual cross-sectional view when filling of a pattern hole with a paste is completed.

FIG. 52 is a conceptual diagram showing a relationship between a moving direction of a squeegee and a distribution density of particles in a paste.

FIG. 53 is a conceptual diagram of a print mask having a groove on a side wall of a pattern hole.

FIG. 54 is a conceptual view showing particles and a fluid pool in a print mask having a groove on a side wall of a pattern hole.

FIG. 55 is a cross-sectional view showing the shape of a groove and its peripheral portion.

FIG. 56 is an apparatus for manufacturing a grooved excimer laser mask according to the present invention.

FIG. 57 is a conceptual diagram of an exposure step in the additive manufacturing method.

FIG. 58 is a conceptual diagram of a developing step in the additive manufacturing method.

FIG. 59 is a conceptual diagram of a plating step in an additive manufacturing method.

FIG. 60 is a diagram showing a state in which a laser beam shaped by a light blocking aperture is irradiated on a mask material.

[Explanation of symbols]

 Reference Signs List 25 light-shielding plate (aperture) 27 plastic plate 50 paste 50a coarse part of particle density 50b dense part of particle density 51 squeegee 53 groove 54 spherical solid particle 55 fluid reservoir 56 excimer laser generator (laser source) 69 shaping unit 70 Pattern hole 71 Welcome side wall

Claims (3)

[Claims] 1. A printing mask provided with a pattern hole for printing, wherein the mask placed on the surface of a printing substrate is rubbed with a squeegee to form a viscous fluid containing spherical particles. When the viscous body is spread on the surface of the printing material in a pattern shape corresponding to the pattern holes by spreading the body, thereby filling the pattern holes with the viscous body, and then separating the printing mask from the plate. In the printing mask for the paste containing particles to be used, grooves having a width slightly smaller than the diameter of the spherical particles are provided at predetermined intervals on the side walls of the pattern holes provided in the printing mask, and the grooves are formed in the printing mask. A print mask for paste containing particles, wherein the print mask is extended in a thickness direction. 2. The particle-containing paste according to claim 1, wherein the cross-sectional shape of the groove is any one of a triangular shape, a rectangular wave shape, a sine wave shape, a semicircular shape, and an elliptical shape. Printing mask. 3. A laser source for emitting an excimer laser beam, an aperture having a side wall formed in a cross-sectional shape of the groove and a shaping hole for shaping the excimer laser beam into a predetermined shape, or a reflection surface. A shaping / reflecting surface formed in a cross-sectional shape of the groove; a shaping / reflecting surface for shaping and reflecting the excimer laser light into a predetermined shape; and applying the shaped excimer laser light to a mask material An apparatus for manufacturing a print mask for particle-containing paste, wherein the print mask for forming a pattern hole for printing according to claim 1 or 2 is formed.