JP3656684B2 - Printing paste for paste containing particles and manufacturing apparatus thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a particle-containing paste printing mask used for forming a pattern with a viscous paste on a surface of an object to be printed using a stencil printing technique, and an apparatus for manufacturing the same.
[0002]
[Prior art]
As a method of soldering the board and parts in the mounting process of the electronic board, starting with soldering with a soldering iron, dipping method in which the joint is immersed in a molten solder bath, while immersing the joint surface in molten solder jetted upward by a nozzle A reflow method for passing through has been put into practical use. At present, the reflow method, which is an application of printing technology, has become the mainstream.
[0003]
Cream solder is a mixture of fine solder powder and flux, which is printed on a pad, which is a joint on the electronic board, and the lead part of the electronic component to be soldered is mounted on the solder. Using the viscosity, the components are transported while being held on the substrate and passed through a heating furnace called a reflow furnace. At that time, cream solder is dissolved and the pads of the substrate and the component leads are soldered.
[0004]
In such a reflow process, a very important one is a printing mask used for cream solder printing.
[0005]
Normal printing methods can be broadly classified into transfer types represented by letterpress, flat plate, and intaglio, and copy types represented by copying plates, stencils, and silk screens. The printing mask used for the printing of the cream solder on which is placed is a copying type printing mask.
[0006]
In this copying printing, printing methods using a stencil printing plate include an etching mask, an additive mask, a YAG laser mask, and the like, and an excimer laser mask using a plastic plate for the printing plate.
[0007]
These masks are all considered to secure the amount of paste to be printed, but the printing area is often limited by the requirements of the printing side, in which case the amount of paste is ensured. Therefore, the thickness of the mask is important.
[0008]
Therefore, a printing mask plate having a specified thickness is used.
[0009]
Thus, in order to secure the printing amount of the paste, the mask plate needs to have a certain thickness. Therefore, the thicker the mask plate or the smaller the opening area, the more the state of the inner wall of the printed pattern hole is lost. The effect on sex will increase, and the omission will become worse.
[0010]
In addition, the detachability of the paste is greatly affected by the unevenness of the cross-sectional shape of the printed pattern, the surface roughness of the inner wall, the surface energy of the inner wall surface (wetting properties, water repellency) and the like, which differ depending on the mask plate manufacturing method.
[0011]
Therefore, first, the progress of print mask manufacturing technology related to the unevenness of the cross-sectional shape of the print pattern hole and the surface roughness of the inner wall will be described.
[0012]
FIGS. 1 to 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.
[0013]
In FIG. 1, reference numeral 1 denotes a metal plate used as a plate material, most of which is stainless steel SUS304.
[0014]
Then, after removing the roll wrinkles, hairline processing, degreasing, etc., the photoresist 2 is applied, and the photo film 3 is adhered from both sides as shown in FIG.
[0015]
When the photoresist is washed and developed after a certain aging time, masking of a necessary design by the coating film of the photoresist 2 can be performed as shown in FIG. 3, while the stripped portion 5 of the photoresist is formed.
[0016]
After inspection and treatment of masking pinholes, damage, dirt, etc., and processing with an etching shower device as shown in FIG. 4, the unmasked portion of the plate material 1 is dissolved by the etching solution 6 such as ferric chloride. In a few minutes, a printed pattern hole as shown in FIG. 5 is formed. Thereafter, the photoresist is peeled off and neutralized.
[0017]
The etching mask manufactured in this manner has a convex portion 7 at the center of the printed pattern hole as shown in FIG. 5 and the surface roughness of the inner wall surface of the printed pattern hole is rough, so that it is easy to remove in paste printing. The print quality is poor.
[0018]
The additive mask manufacturing method is also called an electroforming method. FIGS. 6 to 9 are conceptual diagrams showing the additive mask manufacturing method in section, and FIG. 10 is a conceptual diagram of the printed pattern holes.
[0019]
In FIG. 6, a dry film 9 made of a photosensitive resin is laminated on the surface of a substrate 8 that becomes an electrode at the time of plating, and when the thickness is insufficient, a dry film 9 is further formed thereon via a photosensitive adhesive 10. Laminate to add thickness.
[0020]
Next, when the photomask 11 patterned as shown in FIG. 7 is brought into close contact with the dry film 9 and exposed by the exposure light source 12 and developed after a certain aging time, it is cured and insolubilized as shown in FIG. A female mold 13 having a printed pattern hole shape by a dry film remains on the substrate 8.
[0021]
When the substrate 8 with the female mold 13 is placed in an electrolytic nickel plating solution as shown in FIG. 9 and energized on the cathode side, nickel is deposited on the surface of the substrate 8 and gradually around the female mold 13 of the dry film. The deposited nickel layer 14 grows and becomes thicker.
[0022]
When the deposited nickel layer 14 reaches a predetermined thickness, it is pulled up from the plating solution, and after neutralization, the deposited nickel layer 14 is peeled off from the substrate 8 and the dry film female mold 13 is removed. Pattern holes can be obtained.
[0023]
The shape of the inner wall of the printed pattern hole is relatively flat reflecting the shape of the female mold 13 of the dry film, and the print quality is better than that of the etching mask, so that it is suitable for fine printing.
[0024]
However, sometimes, a belt-like portion having a rough surface or a step 15 as shown in FIG. 10 is generated on the inner wall surface corresponding to the portion of the photosensitive adhesive 10 to which the dry film is bonded.
[0025]
In addition, since the photosensitive adhesive 10 has a slightly low light transmittance, it is masked when the exposure time is extended to expose the bottom of the dry film 9 to the substrate side sufficiently or when it is exposed to strong light. In addition, there is a wraparound of light due to halation to the place that originally becomes a shadow, and unevenness 16 may occur on the inner wall surface of FIG.
[0026]
The irregularities 16 occur on the inner wall on the light source side with the photosensitive adhesive 10 as a boundary, and are said to be “overexposure phenomenon”, “attack phenomenon”, “break”, etc., and have a shape that impairs printability. It is.
[0027]
The YAG laser mask is a printing mask of a relatively new manufacturing method. FIGS. 11 to 13 are conceptual diagrams showing the YAG laser mask manufacturing method in cross section, and FIG. 14 is a conceptual diagram of the YAG laser mask opened as a result. .
[0028]
In FIG. 11, reference numeral 17 denotes a metal plate used as a plate material, most of which is stainless steel SUS304. This SUS304 is almost the same as the metal plate 1 used for the etching mask, but the etching mask uses a material that has been cold-rolled several times or more, whereas the YAG laser requires a large number of rolling operations. do not do.
[0029]
After removing the roll wrinkles and the like, the metal plate 17 is heated and melted by the YAG laser beam 18 but cannot be cut only by this, so the metal 20 is removed by the assist gas 19.
[0030]
FIG. 12 shows a cutting procedure. The first drilling of the through-hole 21 is called piercing. However, the machining range at this time tends to be widened, and when piercing is performed on the planned cutting line, only that portion protrudes to the outside, so as shown in the figure In addition, the piercing is performed at the portion to be removed, and then the cutting process is performed so as to join the planned cutting line.
[0031]
In the cutting with this YAG laser, as shown in FIG. 13, the melted dross 22a is fixed to the cutting edge and cannot be used as a printing mask as it is, so the dross 22a is removed by polishing the surface.
[0032]
At this time, if the occurrence of the burrs 22b in the printed pattern holes is remarkable, it may be a factor that hinders the ability of the paste to be removed during printing, so the burrs 22b may be further removed by electrolytic polishing.
[0033]
As shown in FIG. 14, the completed printed pattern hole has severe irregularities 23 on the inner wall surface, and the print quality is higher than the etching mask, but lower than the additive mask.
[0034]
Temporary CO ₂ Although a similar printing mask was attempted by laser, the thermal effect was more extensive than that of YAG laser, so the irregularities on the inner wall surface were more severe, and sufficient print quality could not be realized as a printing mask. It did not arrive.
[0035]
In this way, stencil masks are also called “metal masks” because the material of the stencil is a metal plate, except for silk screens, which is important in stencil printing of pastes. As a new mask to solve the poor adhesion with metal mask, limit of fine processing, long delivery time and high cost due to manufacturing method and material, printing pattern with excimer laser using plastic plate as plate material A device for performing hole drilling has appeared (see Japanese Patent Laid-Open No. 7-81027).
[0036]
This mask is called “excimer laser mask” when focusing on the manufacturing method, and “plastic mask” when focusing on the material of the plate. Hereinafter, although referred to as an “excimer laser mask”, FIGS. 15 to 18 are conceptual diagrams showing a method of manufacturing the excimer laser mask in cross section, and FIG. 19 is a conceptual diagram of the excimer laser mask opened as a result.
[0037]
In FIG. 15, 24 is the range of the beam light of the irradiated excimer laser. Beam light 24 is a linear YAG laser or CO ₂ The cross section of the beam light 24 of the excimer laser is a surface with respect to the laser, and this is adjusted to an arbitrary shape by the opening shape opened in the light shielding plate (aperture) 25, and the energy density that can be condensed by the lens 26 and processed. After being obtained, the plastic plate 27, which is a mask plate material, is subjected to opening processing.
[0038]
FIG. 16 is a conceptual diagram of a plastic processing principle using an excimer laser. The plastic, which is a polymer, has innumerable atoms 28 solidified by covalent bonds, but when irradiated with laser light 29 through the aperture 25 with a certain energy or more, it was stable in the trajectory of the base. Electrons are excited and leave the shared orbit and move up one orbit.
[0039]
For this reason, the covalent bond is not established as shown in FIG. 17, and the cleaved atoms 30 are scattered at a high speed. As a result, digging is performed on the plastic surface in the laser beam irradiation range.
[0040]
The amount of digging with a single laser beam irradiation is often 1 μm or less, but by repeating this process, digging at an arbitrary depth is possible and digging more than the thickness of the plastic plate of the mask material. When processed, it becomes a through hole.
[0041]
Such processing using an excimer laser is called ablation processing. At that time, the temperature of the scattered atoms can be as high as 6,000 degrees, but a series of mechanisms is completed in a short time of 20 nanoseconds, so there is no room for sufficient conduction of heat to adjacent atoms. Also say.
[0042]
As described above, the excimer laser ablation processing is easily affected by thermal, chemical, and mechanical effects and can easily perform extremely fine planar processing at the wavelength level and the atomic level.
[0043]
FIG. 18 shows the state of processing, and FIG. 19 shows the shape of the printed pattern hole obtained as a result. The processing state is very good like the inner wall surface 31, and the print quality is the above-mentioned etching mask. , Surpassing additive masks and YAG laser masks.
[0044]
20 to 32 are cross-sectional views of a defective shape with poor paste removal caused by such a printing mask manufacturing method, and an explanatory diagram of the cause of the occurrence.
[0045]
Fig. 20 shows a defect shape with rounded edges of the printed pattern holes. For example, when the punch press side of a punch press mask that has been produced for a period of time or when excessive time is required to remove burrs and burrs by electrolytic polishing. Occur. Compared to a mask with a good edge, it is inferior in the filling property of the paste, and the omission property is deteriorated.
[0046]
FIG. 21 shows a defect shape with burrs on the upper or lower edge of the printed pattern hole, which is generated on both the front and back surfaces by the DAG polishing of the YAG laser mask and on the die side of the punch press mask. It is also a shape that deteriorates the slip-out property.
[0047]
FIG. 22 shows a defect shape called “zigzag” in which irregular concave portions are generated at the edge of the edge of the printed pattern hole. As shown in FIG. 23, the mask is masked by the etchant 6 during the etching mask manufacturing process. This occurs when the photoresist 2 for printing is partially peeled off from the metal plate 1 for printing, and may occur on both the front and back sides.
[0048]
In addition, as shown in FIG. 24, the periphery of the minute print pattern hole of the additive mask may be protected by a mask 32 for limiting the etching range, and half-etching may be performed to reduce the mask thickness by etching.
[0049]
If the filling of the resin 33 for protecting the inner wall of the printed pattern hole performed at this time is insufficient, the etchant oozes into the gap generated between the inner wall and the resin as shown in FIG. 24, and the ridge line 34 at the edge of the printed pattern hole is etched. It is etched by the liquid and becomes gritty. This also causes inferior paste filling and detachability.
[0050]
FIG. 25 shows a typical defect shape in an etching mask in which the central portion of the inner wall of the printed pattern hole has a convex shape. As shown in the manufacturing method of FIG. 1 to FIG. 4, the exposed metal plate 1 is exposed by etching away from the front and back of the metal plate 1, and the exposed metal plate 1 is dug into a pan-bottom mold with the center of the exposed part deep and the peripheral part shallow. To go.
[0051]
Therefore, when the etching holes proceeding from both the front and back surfaces become continuous holes, the central convex portion 7 shown in FIGS. 5 and 25 is generated. This shape hinders the passage of the paste and impairs the ability to escape. Further, since the inner wall surface is etched by etching, the surface roughness is rough, and the print quality is further deteriorated.
[0052]
Although it is the etching mask that was most practically used as the metal mass 7, the print quality is inferior to any of the YAG laser mask, additive mask, and excimer laser mask, and is not suitable for precise printing.
[0053]
FIG. 26 shows an excessively tapered defect shape generated in the additive mask. FIGS. 6 to 9 show the manufacturing method of the additive mask. In the exposure process of FIG. 7, when a light source 35 that scatters as shown in FIG. It becomes a cross-sectional shape.
[0054]
If the printed pattern hole inner wall of the printing mask is vertical, the printability is determined by the tacking force of the paste on the printed material and the shear between the inner wall of the mask and the paste that tries to peel the paste from the surface of the printed material according to the separation of the plate. Determined by stress.
[0055]
However, as the inner wall tapers, the tacking force between the inner wall surface and the paste increases, and counters the tacking force between the surface of the substrate to be printed and the paste, thereby deteriorating the detachability.
[0056]
FIG. 27 is a conceptual diagram of exposure with the scattering light source 35. The light incident from the transparent pattern portion of the photomask 11 is a portion 36 where the light from the light source 35 does not reach the dry film 9 at all. Differences in exposure conditions occur between a portion 37 where some light reaches and a portion 38 where all light reaches.
[0057]
In particular, in the portion 37 where some light reaches, the amount of light on the side close to the portion 36 where no light reaches is small, and on the side close to the portion 38 where all light reaches, much exposure is performed, so the exposure conditions are continuous. Has changed.
[0058]
If the dry film 9 exposed under such a scattering light source has a high exposure sensitivity, the dry film 9 has a cured and insolubilized shape including the area 37 where light can reach as shown in FIG. 28, and the exposure sensitivity is low. Then, as shown in FIG. 29, the shape does not include the range of the part 37 where a part of light reaches.
[0059]
In order to cope with such an excessive taper shape, in order to perform exposure with parallel light, a honeycomb structure shielding plate is placed in the middle of the optical path to shield only oblique light from the inner wall surface of the honeycomb, or an ultraviolet lamp of the light source is released. Due to improvements such as the installation of the mirror at the focal point of the object mirror and the use of the parallel reflected light, the excessive taper shape has now been reduced.
[0060]
FIG. 30 shows a defect shape in which the step 15 is generated on the inner wall of the print pattern hole, which is unique to the additive mask.
[0061]
In the above-described additive mask manufacturing method, as shown in FIG. 6, a plurality of dry films 9 are laminated with a photosensitive adhesive 10 to cope with the thickness of the mask. If there is a difference in the photosensitivity of the film or the solubility during development, a step 15 as shown in FIGS. 10 and 30 occurs. This shape is also a defective shape that hinders the ability to remove the paste.
[0062]
In response to this, a thicker dry film has been provided, and it is becoming easier to avoid the use of the photosensitive adhesive 10.
[0063]
FIG. 31 is also a problem caused by laminating the dry film 9 with the photosensitive adhesive 10 in the shape called “overexposure phenomenon”, “attack phenomenon”, “comb” 57 ′, etc., which is peculiar to the additive mask. .
[0064]
When the laminated dry film is exposed, the exposure is performed as shown in FIG. 7 in an upside down manner as shown in FIG. 31. However, when the thickness of the mask to be manufactured is thick, the light transmittance at the portion of the photosensitive adhesive 10 is increased. Because it is bad, there is a risk that the bottom of the dry film will not be fully exposed.
[0065]
To cope with this, long exposure or large light exposure is performed. If this is excessive, the shadow portion shielded by the photomask is exposed by halation in the dry film, resulting in irregularities 16 on the inner wall surface. The unevenness 16 is also a factor that hinders the removal of the paste.
[0066]
FIG. 32 shows a problem that occurs in the etching mask. 2. Description of manufacturing method As shown in FIG. 2, two photo films 3 are used for the exposure of the etching mask. Usually, alignment marks called register marks are set on the photo film, whereby the upper and lower films are formed. Adjust the position so that it does not slip, and stick it together in a bag and use it.
[0067]
If the manufacturing is performed with the alignment being shifted, such an inclined printed pattern hole shape is generated in the etching mask. This defect not only deteriorates the ability to remove the paste, but also varies the print quality depending on the moving direction of the squeegee.
[0068]
FIG. 33 is a conceptual diagram showing paste removal when the pattern hole cross-sectional shape of the printing mask is good, and FIG. 34 is a conceptual diagram showing the removal property when the pattern hole cross-sectional shape is poor.
[0069]
FIG. 35 is a conceptual diagram showing the defect shape due to the difference in the ability to remove the paste in the printing of the slit hole shape.
[0070]
The defect “no paste” in FIG. 35 is that the paste could not be removed from the print pattern holes and was not printed on the surface of the printing material. “Paste missing” is a partially clogged portion of the printed pattern hole that is poorly removable.
[0071]
“Make-up” means that the shear stress caused by the poor detachment on the mask side when separating the plate and the tacking force on the surface of the printed material pull the paste, and once the paste is partially peeled off from the surface of the printed material, After that, it has fallen to the surface of the printed material, and in many cases, the paste deviates from the position where printing is desired.
[0072]
There are many ways to describe “tsu”, such as “saddle-shaped”, “saddle”, and “threading”. However, if the pattern hole part with poor detachment pulls the surface of the substrate to be printed and the paste when separating the plate, Due to the stringiness, it becomes a defective shape as shown in the figure.
[0073]
“Bridge” has a more severe degree of “one” and is called “short” when the adjacent pattern is in contact with the defective paste shape, especially when the paste is used for electrical circuit formation. There is.
[0074]
In the above, the print pattern hole formation technology of the mask has been described from the viewpoint of print quality. It has been found that it also depends on wettability and water repellency.
[0075]
Therefore, when a printing mask having a Teflon coating layer 44 on the inner wall of the printing pattern hole as shown in FIG. 36 or a printing mask plate by the additive method as shown in FIG. 37, the Teflon is used in the electrolytic nickel plating solution 45 to be used. A printing mask by a “composite plating method” has been proposed in which a part of the Teflon fine particles 46 are dispersed and exposed on the plating surface as shown in FIG.
[0076]
These printing masks have not been widely used due to their high price, but their removal has been greatly improved.
[0077]
However, in addition to the improvement in the cross-sectional shape of the opening, the printed pattern hole shape is fine and the slit shape 47 as shown in FIG. In this case, the paste tends to clog the corners at both ends of the hole.
[0078]
This is because the ratio of the inner wall area of the corner portion is large with respect to the tacking area between the surface of the substrate to be printed and the paste, and the shear stress that tries to peel off the paste when the plate is released is the largest at the corner portion.
[0079]
From this, it can be seen that the shear stress has not been completely removed by the water-repellent processing on the inner wall of the printed pattern hole of the current printing mask.
[0080]
40 and 41 are plan and sectional conceptual views in the same printing, and show examples of paste clogging tendency. When the printing pattern holes of the round shape 48, the square shape 49, and the slit die 47 are formed on the printing mask and the paste 50 containing spherical particles is printed, the squeegee 51 is downward from the top in FIG. 40 and from left to right in FIG. When squeezing is performed, the paste 50 tends to clog the lower pattern hole side wall in FIG. 40 and the right pattern hole side wall in FIG.
[0081]
This depends on the squeegeeing direction. The squeezing direction is from bottom to top in FIG. 42 and from right to left in FIG. 43. In both cases, the paste 50 is applied to the pattern hole side wall in front of the squeegee in the traveling direction. Easy to clog.
[0082]
44 to 47 show a mechanism for filling a printed pattern hole with paste, which has been conventionally described.
[0083]
In FIG. 44, when the squeegee squeezes the paste placed on the printing mask in the right direction, the paste pressed from the back while sticking to the mask plate surface is rolled in the right direction as indicated by the arrow in FIG. When the print pattern hole is advanced, the paste is sequentially filled from the front side of the opening as shown in FIGS. 45, 46 and 47.
[0084]
However, when actually observed, the filling mechanism was as shown in FIGS.
[0085]
48 to 51, when the squeegee is squeezed to the right in the figure, the paste placed on the printing mask is slipping on the printing mask plate surface while rolling.
[0086]
In FIG. 48, the paste reaches before the opening. In the conventional explanation, the paste should be filled in the printed pattern hole after this, but actually, even if the paste crosses the pattern hole opening, it does not fill the opening.
[0087]
In FIG. 49, when the tip of the paste reaches the opening edge on the front side in the traveling direction of the squeegee and slips further forward, the bottom of the paste is caught on the front edge and is filled from the bottom. Begins.
[0088]
The paste filled in the opening retains the bottom of the paste passing through the upper part of the pattern hole, and the retained paste is pushed by the paste coming from behind and swells downward. The inside of the opening is filled.
[0089]
In this way, the paste is completely filled into the space in the opening before the squeegee passes over the printed pattern hole.
[0090]
Further, when the state of the filled paste was observed, as shown in FIG. 52, a portion 50a having a coarse particle density was found in the space in the opening on the rear side with respect to the traveling direction of the squeegee. The portion in contact with the side wall on the front side has a dense particle portion 50b, and a difference in particle distribution occurs.
[0091]
The dense portion of the particle distribution coincides with the distribution of the paste containing the spherical solid that clogs the pattern hole side wall in the forward direction of the squeegee in FIGS. There is a correlation between the omission of the paste at the time.
[0092]
This correlation is explained by the surface energy associated with wettability. Paste containing solid particles retains the properties of the paste by filling between the contained particles with a viscous liquid. However, if the ratio of viscous liquid to solid particles is high, the viscosity of the paste as a whole decreases and fluidizes. It becomes easy.
[0093]
Conversely, when the ratio of the viscous liquid decreases, the viscosity becomes high and the shape retention tendency increases.
[0094]
This is because the viscous liquid between solid particles functions as a lubricant between particles above a certain content, but conversely, when the content falls below a certain content, the surfaces of the solid particles and the viscous liquid wet each other. At the same time, the particles are attracted by the surface tension of the viscous liquid, so that the solid particles are restrained from each other by the viscous liquid and become difficult to move.
[0095]
This mechanism works not only between the solid particles but also between the solid particles and the side wall of the printed pattern hole. Therefore, the paste with a low solid particle density and high viscosity liquid ratio filled in the space inside the opening on the rear side with respect to the direction of squeegee travel is It is also fluid and slippery with respect to the side wall, and as a result, it becomes a part with good detachability.
[0096]
On the other hand, a paste with a high solid particle density and a low viscosity liquid ratio that is in contact with the side wall of the opening on the front side in the direction of travel of the squeegee is non-fluid and non-slipable with respect to the side wall, resulting in a poorly removable part.
[0097]
To date, countermeasures have been taken against the poor detachability caused by the shape of the inner wall of the printed pattern hole, the poor detachability caused by the surface roughness of the inner wall surface, and the poor detachability caused by the lubricity of the inner wall surface. Although there has been no effective countermeasure against the variation in the detachability of the solid particle-containing paste that correlates with the squeezing direction, and there is an increasing demand for fine printing, a new countermeasure technology is required. Yes.
[0098]
[Problems to be solved by the invention]
As described above, in stencil printing using a stencil, various measures have been taken to secure the omission property, which has been a problem in the past, but it is still not possible to deal with clogging that correlates with the squeezing direction. There is no effective countermeasure and an immediate response is desired.
[0099]
Accordingly, an object of the present invention is to provide a particle-containing paste printing mask and a manufacturing apparatus therefor that are less likely to cause clogging correlated with the squeezing direction as described above.
[0100]
[Means for Solving the Problems]
The invention according to claim 1 is a printing mask having a pattern hole for printing, which is rubbed with a squeegee on the mask placed on the surface of the printing material, and contains spherical particles in the viscous fluid. The viscous material is spread and spread, and the viscous material is then filled in the pattern hole, and then the printing mask is released to transfer the viscous material to the surface of the substrate in a pattern shape corresponding to the patterned hole. In the particle-containing paste printing mask used in the process, 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 pattern hole provided in the printing mask. Is extended in the thickness direction of the printing mask.
[0101]
That is, a groove is provided on the side wall of the pattern hole to ensure slippage between the viscous body containing the spherical particles filled in the pattern hole and the side wall of the pattern hole, and the viscous flow contained in the viscous body is included in the groove. Let the body accumulate. The viscous fluid is made to act as a lubricant.
[0102]
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.
[0103]
According to a third aspect of the present invention, there is provided a laser source that emits excimer laser light, an aperture having a side wall formed in a cross-sectional shape of the groove, and a shaping hole that shapes the excimer laser light into a predetermined shape, or a reflecting surface Including a shaped reflection surface formed in a cross-sectional shape of the groove, and having a shaped reflection surface that shapes and reflects the excimer laser light into a predetermined shape, and masks the shaped excimer laser light. The pattern hole for printing is formed by irradiating the material.
[0104]
That is, when forming a mask having a groove on the side wall of the pattern hole, the excimer laser beam is shaped into the shape of the pattern hole by the aperture or mirror, and the groove shape is formed on the shaping reflection surface of the aperture or mirror. And the groove is formed simultaneously with the formation of the pattern hole.
[0105]
DETAILED DESCRIPTION OF THE INVENTION
Since the present invention is more useful for fine printing, which was difficult with a conventional printing mask, it is desirable to combine it with a mask that has already been printed in normal printing with good print quality, and an etching mask or YAG laser with poor print quality. Not familiar with masks. Therefore, embodiments of the present invention in an additive mask and an excimer laser mask will be described below.
[0106]
In the method of forming the pattern hole shape of the printing mask according to the present invention by the additive manufacturing method, FIGS. 7 and 57 show the schematic structure of the exposure process, FIGS. 8 and 58 show the development process, and FIGS. 9 and 59 show the plating process.
[0107]
In the exposure process shown in FIGS. 7 and 57, a photosensitive dry film 9 is laminated to a necessary thickness on a substrate 8 which is an electrode substrate for electrolytic plating, and a design to be formed on the surface for determining an exposure shape is formed on a transparent portion. When the photomask 11 designed separately for the light shielding part is brought into close contact by vacuum suction or the like and exposed by a parallel ultraviolet light source 12 such as an upper high pressure mercury lamp, a latent image as designed by the photomask 11 is formed on the dry film 9. can get.
[0108]
At this time, in order to form the groove according to the present invention on the pattern hole side wall of the printing mask, the uneven pattern 64 for forming the groove shape is used as a design of the photomask 11.
[0109]
Further, in the development process of FIGS. 8 and 58, when a predetermined development is performed with the photosensitive resin developer 65 to visualize the latent image, the plating pattern hole plating female mold 66 according to the present invention is obtained on the substrate 8. .
[0110]
9 and 59, the substrate 8 with the plating female mold 66 is connected to the negative side of the electroplating power source 67, and the electroforming nickel anode 68 is connected to one positive side. When immersed in the electrolytic plating solution 45 and energized for a certain period of time and plated with a necessary thickness, a metal plate for a printing metal mask having a groove shape with a printing pattern according to the present invention is obtained by the additive manufacturing method. It is done.
[0111]
Thereafter, the metal plate is peeled off from the substrate, and the plating female mold 66 is dissolved and removed, and then bonded to the printing frame via a tension applying film made of polyester or nylon, thereby completing a printing mask. .
[0112]
On the other hand, the following is a method of forming the pattern hole shape of the printing mask according to the present invention by using an excimer laser mask. FIG. 56 is a diagram showing a schematic configuration of an apparatus for forming a grooved excimer laser mask according to the present invention. An excimer laser generator 56 that emits excimer laser light (hereinafter simply referred to as laser light), a prism or mirror 57 (57a, 57b, 57c) that changes the optical path of the laser emitted from the excimer laser generator 56, A homogenizer for uniformizing the intensity distribution of the laser beam, a beam adjusting unit 58 having a beam expander or beam compressor for reducing / enlarging the length and minor axis of the laser beam, and a light blocking aperture for making the laser beam into a predetermined pattern Alternatively, a beam forming unit 59 of a reflection mirror, a condensing lens 60 for condensing laser light, It has a stage 61 that holds a plastic plate of a disk material and moves it in the XYZ axis direction, a control unit 62 that controls the positioning of the aperture stage and the excimer laser generator 56, and a camera 63 for an observation optical system. ing.
[0113]
FIG. 60 is a diagram showing a state in which the plastic plate of the mask material is irradiated with the laser light shaped by the light blocking aperture or the beam forming unit 59 of the reflecting mirror in FIG.
[0114]
The beam forming unit 59 is provided with a plurality of shaping holes 69 corresponding to the pattern holes. Of course, the number of shaping holes may be one, and is set according to the pattern to be formed as appropriate.
[0115]
On the inner peripheral side wall of the shaping hole 69, a groove having a magnification that is the reciprocal of the reduction ratio of the condenser lens 60 is provided. Therefore, a groove 53 is also formed in the pattern hole of the mask formed by the beam forming portion 59 as shown in FIG.
[0116]
The width of the groove 53 is set to be slightly smaller than the particle diameter contained in the paste filled in the putter hole.
[0117]
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 in the central portion and weak in the peripheral portion, and the distribution is non-uniform. When this non-uniformity adversely affects processing, the homogenizer of the beam adjustment unit 58 may be used for homogenization.
[0118]
In addition, the cross-sectional shape of the emitted laser light is often a rectangle with slightly rounded corners, and when this shape adversely affects processing, the long and short diameter dimensions of the laser light are also measured by the beam compressor of the beam adjusting unit 58. Is reduced or expanded by a beam expander to adjust to the required beam.
[0119]
After that, the laser light whose optical path is adjusted so as to be perpendicularly incident on the mask 59 by the prism or mirror 57 (57a, 57b, 57c) is shaped by the light forming aperture 59 or the beam forming part 59 of the reflecting mirror, and is collected by the condenser lens. 60 is projected.
[0120]
The projected laser beam has an increased energy density per unit area and can exceed the energy density necessary for the ablation process specific to each material, so that pattern holes are formed in the mask. The
[0121]
When the pattern hole is formed in the mask, the control unit 62 positions the light shielding aperture or reflection mirror beam forming unit 59 and the stage 61, and processes the next pattern hole.
[0122]
In the present invention, a groove is provided on the side wall of the pattern hole. Since the interval between the adjacent grooves is very small, if the aperture or mirror pattern of the forming part 59 and the processing shape of the mask are equal, the forming part Creating 59 apertures or mirrors is difficult and costly.
[0123]
However, since the apparatus is reduced and projected by the condenser lens 60 as described above, the pattern formed on the light blocking aperture or the beam forming portion 59 of the reflection mirror may be larger by a reciprocal of the reduction ratio. And the manufacturing cost of the mirror can be reduced, so that the manufacturing cost of the printing mask can also be reduced.
[0124]
In addition, it is difficult for ablation to occur with excimer laser light, and if the mask material contains fine particles having a diameter matching the width of the groove 53, the mask base material is not processed in the shadow of the fine particles. The groove 53 can be formed naturally.
[0125]
In this manufacturing method, variations such as the pitch and depth of the groove arrangement occur, but it is not necessary to provide the groove 53 in the shaping hole 69 depending on the application.
[0126]
Next, the operation principle of the present invention will be described. Conventionally, by reducing the shear stress between the side wall of the printing mask and the filled particle-containing paste 50, the side wall surface is made as much as possible so that the paste does not remain in the pattern hole 70 when the printing mask is released. It was smooth.
[0127]
However, as a result of observing in detail the clogging state of the paste and how the paste is filled in the pattern holes, the present inventor has found the following.
[0128]
In other words, the paste clogged when the plate is separated tends to remain on the side wall (hereinafter referred to as the “attacking side wall”) where the inner wall faces the sliding squeegee directly facing, and this tendency includes particles in the pattern holes. This was closely related to the mechanism by which the paste 50 was filled.
[0129]
This will be described with reference to FIGS. 48 to 51, in which a mechanism for filling the pattern hole 70 with the particle-containing paste 50 is described. The arrows in the figure indicate the movement of the particle-containing paste 50.
[0130]
48 to 51, the solid particle-containing paste 50 that is pushed and moved by the sliding squeegee 51 slips and moves forward while rolling on the mask plate surface.
[0131]
In FIG. 48, the paste reaches the pattern hole 70, but after that, even if the paste 50 crosses over the opening of the pattern hole 70, it is not filled into the opening. In FIG. The bottom of the paste is caught on the edge of the front-facing side wall 71, and the filling starts as if the paste 50 is scraped off from below with a plane.
[0132]
The paste 50 filled in the opening of the pattern hole 70 retains the bottom of the paste 50 passing through the upper part of the pattern hole 70. Furthermore, the retained paste 50 is pushed by the paste coming from behind. , The opening is filled so as to swell downward.
[0133]
Thus, the paste finally fills the space in the opening until the squeegee passes over the printed pattern hole.
[0134]
As shown in FIG. 52, the state of this filled paste is as follows. In the space in the opening on the rear side with respect to the direction of travel of the squeegee, a coarse portion 50a having a solid particle density is present. A portion in contact with the side wall includes a dense portion 50b having a solid particle density, and a difference in particle distribution occurs.
[0135]
When the paste containing solid particles such as the paste is pressed against the incoming side wall, the solid particle density is increased toward the incoming side wall 71a, but the liquid component in the paste is easily applied to the opposite side wall 71b. Since it can move, such a density distribution is generated as it is squeezed out.
[0136]
As a result, when separating the plate, the side wall 71b side where the content ratio of the liquid component in the paste is large and the particle density is small, the liquid component functions as a lubricant, so the shear stress with the side wall is reduced, Omitting property is improved.
[0137]
On the other hand, when the solid particle density is high, there are few liquid components that serve as lubricants, and when the gaps between solid particles are small, the liquid components that function as lubricants are constrained by their wettability due to surface energy. Attract particles and start restraining movement.
[0138]
In this way, the fluidity of the portion where the solid particle density is high is lost, and a phenomenon occurs in which the solid particles are constrained and attracted even in the gap between the solid particles and the inner wall surface. As a result, clogging of solid particles frequently occurs at the portion of the side wall 71a.
[0139]
In this way, rather than the density of solid particles in the paste due to the filling mechanism, the opposite phenomenon of promoting pull-out on the one hand and inhibiting the pull-out on the other is generated.
[0140]
Therefore, even if a high-density portion is generated in the solid particles dispersed in the paste, the liquid component in the paste serves as a lubricant, and the solid particles or solid particles lose their fluidity between the lump and the side wall 71. If present, clogging of the solid particles can be prevented.
[0141]
Therefore, in the present invention, a groove slightly smaller than the particle size of the solid particles is extended and formed on the side wall of the pattern hole in the thickness direction of the printing mask so that the liquid component in the paste accumulates as a lubricant in the groove. In addition, the side wall shape without unevenness is maintained with respect to the direction in which the paste is removed.
[0142]
As a result, the tendency of clogging of the paste that has occurred due to the squeegee direction can be prevented, and the solid particle-containing paste filled in the pattern holes 70 can be prevented from remaining even if the plate separation speed is increased. Printing is possible.
[0143]
In the above description, the cross-sectional shape of the edge of the groove 53 has been described as a triangular shape, but the present invention is not limited to this, and the rod shape, rectangular wave shape, sine wave shape, half-wave shape shown in FIG. Circular, elliptical, etc. are possible.
[0144]
In this case, in a triangular shape or a rod shape, it is desirable that the corner portion is rounded and chamfered from the viewpoint of protecting the shape from wear and increasing durability.
[0145]
【The invention's effect】
According to the present invention, since the groove having a width smaller than the solid particle diameter is provided on the side wall of the pattern hole, the shear stress is reduced, and the solid particle-containing paste does not remain in the pattern hole when the plate is separated. It has become possible to form a paste pattern having a simple shape on the surface of a substrate.
[0146]
Further, when forming a mask having a groove on the side wall of the pattern hole, it is shaped into the shape of the printed pattern hole by the photomask 11 in the additive mask and by the aperture in the excimer laser mask, and at the same time, the photomask Since the groove forming pattern is also added to the shaping shape of the aperture 11 or the aperture so that the groove can be formed simultaneously with the formation of the printing pattern hole, a high-quality printing mask can be manufactured at a low cost. It was.
[Brief description of the drawings]
FIG. 1 is a conceptual cross-sectional view after applying a photoresist in an etching mask manufacturing method.
FIG. 2 is a conceptual diagram of exposure in a manufacturing method of an etching mask.
FIG. 3 is a conceptual diagram of development in an etching mask manufacturing method.
FIG. 4 is a conceptual diagram of etching processing in a manufacturing method of 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 dry film lamination in an additive mask manufacturing method.
FIG. 7 is a conceptual diagram of exposure in an additive mask manufacturing method.
FIG. 8 is a conceptual diagram of development in an additive mask manufacturing method.
FIG. 9 is a conceptual diagram of plating in an additive mask manufacturing method.
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 the manufacturing method of a YAG laser mask.
FIG. 12 is a conceptual diagram showing a cutting procedure in a manufacturing method of a YAG laser mask.
FIG. 13 is a conceptual cross-sectional view of a cut shape of a YAG laser mask.
FIG. 14 is a concept of a YAG laser mask opened as a result of cutting with a YAG laser.
FIG. 15 is a conceptual diagram showing a 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 excavation processing by ablation.
FIG. 18 is a conceptual diagram of planar processing with 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 with rounded printed pattern hole edges.
FIG. 21 shows a defective shape having burrs on the edge of the upper surface or the lower surface of the printed pattern hole.
FIG. 22 shows a defect shape with a crease on the edge of the upper surface or the lower surface of the printed pattern hole.
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 central portion of the inner wall of the printed pattern hole is convex.
FIG. 26 shows a defective shape in which the inner wall of the printed pattern hole is excessively tapered.
FIG. 27 is a conceptual diagram showing a mechanism of taper generation by a scattered light source.
FIG. 28 is an exposure shape of a dry film with high sensitivity by a scattered light source.
FIG. 29 is an exposure shape of a dry film with low sensitivity by a scattered light source.
FIG. 30 shows a defect shape in which a step is generated on the inner wall of the print pattern hole.
FIG. 31 shows a defective shape due to an overexposure phenomenon that occurs on the inner wall of a printed pattern hole.
FIG. 32 shows a defective shape in which the print pattern hole is inclined.
FIG. 33 shows the shape of the paste that is removed when the pattern hole of the printing mask is good.
FIG. 34 is a conceptual diagram of paste removal when the pattern hole of the printing mask is defective.
FIG. 35 is a conceptual diagram of a defective shape of printing by 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 method for producing a composite plating 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 the state of clogging of paste in the case of slit holes.
FIG. 40 is a schematic plan view showing the tendency of paste clogging due to squeezing from above.
FIG. 41 is a conceptual cross-sectional view showing the tendency of paste clogging 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 cross-sectional view showing the tendency of paste clogging due to squeezing from the right.
FIG. 44 is a conceptual sectional view in the conventional theory showing the behavior of the paste on the mask plate surface.
FIG. 45 is a conceptual sectional view in the conventional theory showing the behavior of the paste reaching the pattern hole end.
FIG. 46 is a conceptual cross-sectional view explaining the mechanism in the conventional theory at the moment when the pattern hole is filled.
FIG. 47 is a conceptual cross-sectional view of the conventional theory when filling is completed.
FIG. 48 is a conceptual cross-sectional view based on observations showing the behavior of the paste on the mask printing plate.
FIG. 49 is a conceptual cross-sectional view showing the behavior of the paste filled in the pattern holes.
FIG. 50 is a conceptual cross-sectional view showing the behavior of the paste filled in the pattern holes.
FIG. 51 is a conceptual cross-sectional view when the paste filling into the pattern hole is completed.
FIG. 52 is a conceptual diagram showing the relationship between the moving direction of the squeegee and the distribution density of the particles in the paste.
FIG. 53 is a conceptual diagram of a printing mask having grooves on the side walls of pattern holes.
FIG. 54 is a conceptual diagram showing particles and fluid accumulation in a printing mask having grooves on the side walls of the pattern holes.
FIG. 55 is a cross-sectional view showing the shape of the 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 process in the additive manufacturing method.
FIG. 58 is a conceptual diagram of a developing process in the additive manufacturing method.
FIG. 59 is a conceptual diagram of a plating step in the additive manufacturing method.
FIG. 60 is a diagram showing a state when the mask material is irradiated with the laser light shaped by the light blocking aperture.
[Explanation of symbols]
25 Shading 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 particles
55 Fluid reservoir
56 Excimer laser generator (laser source)
69 Orthopedics
70 pattern holes
71 Welcome side wall

Claims (3)

A printing mask having a pattern hole for printing, which is rubbed with a squeegee on the mask placed on the surface of the substrate to be coated and spread with a viscous material containing spherical particles in the viscous fluid, Thus, the paste containing particles used for transferring the viscous material to the surface of the printed material in a pattern shape corresponding to the pattern holes by filling the pattern holes with the viscous material and then releasing the printing mask. Printing masks,
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 extend in the thickness direction of the printing mask. A printing mask for paste containing particles. 2. The particle-containing paste printing mask according to claim 1, wherein a 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. A laser source that emits excimer laser light, an aperture having a side wall formed in a cross-sectional shape of the groove, and a shaping hole that shapes the excimer laser light into a predetermined shape, or a periphery of the reflecting surface is a cross-section of the groove A shaped reflection surface having a shaped reflection surface formed in a shape, having a shaped reflection surface that shapes and reflects the excimer laser light into a predetermined shape, and irradiating the mask material with the shaped excimer laser light. An apparatus for producing a printing mask for particle-containing paste that forms a pattern hole for printing according to 1 or 2.

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