JP2005096400A - Print mask manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a print mask manufacturing method capable of suppressing significant disruption in a print pattern due to low removal performance of a print material from a through hole while avoiding the disruption in the shape of a through hole due to irradiation of laser for half-etching processes. <P>SOLUTION: When a material having a thickness of about 150 μm is used as a substrate 2, after a half-etching portion 3 is subjected to a laser processing, the substrate 2 is turned over, and laser is irradiated from the side opposite to the side used in a half etching processing so as to form through holes 4. On the other hand, when a material having a thickness of about 75 μm is used, the substrate 2 is irradiated with laser from the same side with the half-etching portion 3 and the through holes 4 at the same time. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a printing mask manufacturing method for manufacturing a printing mask used for screen printing and having a printing pattern with through holes formed in a non-etched portion and a printing pattern with through holes formed in a half-etched portion. It is.

  2. Description of the Related Art Conventionally, a printing method is known in which a printing pattern made of a printing material such as ink, adhesive, cream solder, or resin is printed on a printing medium using a printing mask. For example, in the field of electronic circuits, a printing method is used in which a fine bump electrode pattern made of cream solder is printed on a circuit board using a printing mask.

  Further, as a printing mask, a mask in which a half-etched portion is formed in addition to a through hole for forming a printing pattern is known. FIG. 1 is a cross-sectional view showing such a printing mask. In the figure, the printing mask 1 has a half-etched portion 3 and a plurality of through holes 4 formed in a base material 2 made of a plastic film, a metal thin film, or the like. The half-etched portion 3 has a surface dug down to a certain depth. The plurality of through-holes 4 are provided not only on the non-etched portion where the half etching of the base material 2 is not performed, but also on the bottom surface of the half-etched portion 3.

  The printing mask 1 having such a configuration is brought into close contact with the upper surface of the electronic circuit board 50 that is the printing body, with the opening side of the half-etched portion 3 facing upward (bottom surface side facing down). The upper surface in the drawing of the printing mask 1 is a printing material printing surface (squeegee surface), and cream solder as a printing material is imprinted by a flat squeegee 51 as shown in FIG. Thereby, cream solder is filled in each through-hole 4. The squeegee 51 is a member having excellent flexibility, and flexes flexibly following the surface irregularities of the printing mask 1 to scrape the printing material in the half-etched portion 3 while scraping the printing material in the bottom surface of the etched portion. Fill the inside with a sufficient amount of cream solder.

  When cream solder is filled in the through-hole 4, the work table 52 that fixes the electronic circuit board 50 is then moved downward in the figure by a driving means (not shown). Then, as shown in FIG. 3, when the printing mask 1 and the electronic circuit board 50 are separated (hereinafter referred to as plate separation) with this movement, the cream solder in each through-hole 4 is applied to the electronic circuit board 50. The electrode pattern is formed by transition. This electrode pattern includes two types of bump shapes having different heights because the through-hole 4 of the half-etched portion 3 is shallower than the through-hole 4 of the non-etched portion. As described above, the half-etched printing mask 1 can simultaneously print a plurality of types of bump shapes having different heights.

  The present applicant has previously proposed the method described in Patent Document 1 as a printing mask manufacturing method having such a half-etched portion 3. This is a method of forming a through hole 4 (perforating process) after forming a half-etched portion 3 (half-etching process) on a plastic substrate 2 by ablation processing by excimer laser irradiation. Since the method is based on laser processing, there is no need to prepare a dedicated light-shielding mask for each printing pattern as in the photolithography method, or to generate a waste liquid of a developing solution or an etching solution. Therefore, it is possible to sufficiently respond to an on-demand production request that is an order for many kinds of products and to reduce environmental pollution.

JP-A-8-192585

  The reason why the printing mask manufacturing method described in Patent Document 1 employs the order in which perforation is performed after half-etching is because the flow from the photolithography method has been taken. However, subsequent research has shown that in order to produce a printing mask by laser processing, the disorder of the shape of the through-hole 4 is effectively suppressed by this order. By performing the laser processing in this order, the situation has been avoided in which the already processed through-hole 4 is irradiated with a laser again at the time of half-etching and its shape is disturbed.

  In addition, when the present inventors perform a half-etching process and then perform drilling by irradiating the base material 2 with a laser beam from the side opposite to the half-etching process, an electrode due to poor solder removability We have also found that pattern disturbance can be suppressed. The reason why the disturbance of the electrode pattern is suppressed is as follows. That is, the half-etched portion 3 is processed by laser irradiation from the opening side. The opening side becomes a printing material imprinting surface as shown in FIG. As in the case of half-etching, when drilling is performed by irradiating laser onto the printing material printing surface, as shown in FIG. 4, the through holes 4 are directed from the printing material printing surface side to the emission surface side. It becomes a tapered shape. When printing is performed using the printing mask 1 having such a configuration, as shown in FIG. 5, the outlet from the through-hole 4 at the time of separating the plate is narrowed, so that the solderability is deteriorated. Then, a sufficient amount of cream solder cannot be transferred to the electronic circuit board 50, which disturbs the electrode pattern. On the other hand, in the printing mask which is punched by laser irradiation from the surface opposite to the printing material imprinting surface, as shown in FIG. 3, the exit from the through-hole 4 when separating the plate is widened. . For this reason, disorder of the electrode pattern due to poor solderability can be suppressed.

  However, the present inventors reduced the thickness of the base material 2 from the current level of 150 to 200 [μm] to about 50 to 75 [μm], which is less than half, in order to cope with further fine patterning in the future. When I was testing, I encountered an interesting phenomenon. In the ultrathin base material 2 of 50 to 75 [μm], even if the through hole 4 is processed in a shape that tapers toward the outlet, the electrode pattern is almost always disturbed due to the poor soldering ability. There was no. This is probably because the depth of the through-hole 4 is reduced, and thus it is less susceptible to reverse taper.

  The present invention has been made in view of the above background, and an object thereof is to provide the following printing mask manufacturing method. A printing mask manufacturing method capable of suppressing the disorder of the printing pattern due to the poor ability to remove the printing material from the through hole while avoiding the disorder of the shape of the through hole due to the irradiation of the laser for half-etching processing It is.

  In order to achieve the above object, the invention according to claim 1 is a printing mask manufacturing method in which a half etching process by laser irradiation and a perforation process are performed on a substrate to form a print pattern including at least a plurality of through holes. After performing the half etching process, the perforating process is performed by irradiating the base material with a laser beam from the side opposite to the half etching process.

  The invention of claim 2 is a printing mask manufacturing method in which a half-etching process and a perforation process by laser irradiation are performed on a substrate to form a print pattern composed of at least a plurality of through holes. The perforating process is performed by irradiating the base material with a laser beam from the same surface side as in the half etching process.

  According to a third aspect of the present invention, in the printing mask manufacturing method according to the second aspect, in the perforating process, the laser beam is condensed by a condensing means having higher resolution than that used in the half etching process. Is.

  According to a fourth aspect of the present invention, in the printing mask manufacturing method according to the first, second, or third aspect, the half-etching process is performed so as to taper a side wall of a half-etched portion formed on the base material. Is.

  According to a fifth aspect of the present invention, in the printing mask manufacturing method according to the fourth aspect, the half-etching process is performed by irradiating the base material with a laser beam having a spot area equal to or larger than a plane area of the half-etched portion. It is what.

  According to a sixth aspect of the present invention, in the printing mask manufacturing method of the fifth aspect, the side wall is tapered by setting the resolution of the light condensing means for condensing the laser light.

  A seventh aspect of the present invention is the printing mask manufacturing method according to the fifth aspect, wherein the side wall is tapered by setting an aperture area of an aperture mask that partially shields laser light irradiated toward the substrate. It is a feature.

  According to an eighth aspect of the present invention, in the printing mask manufacturing method according to the fifth aspect, the side wall is tapered by setting an energy density per unit time at the center of the spot of the laser beam.

  A ninth aspect of the present invention is the printing mask manufacturing method according to the fourth aspect, wherein the substrate is irradiated with a laser beam having a spot area smaller than the plane area of the half-etched portion during the half-etching process. Forming the half-etched portion by gradually expanding the half-etched region in the substrate surface direction while changing the laser irradiation region on the material in the substrate surface direction, and at least of the plurality of side walls in the half-etched portion One taper angle is different from the taper angle of the other side wall.

  A tenth aspect of the present invention is the printing mask manufacturing method according to the ninth aspect, wherein the resolution of the condensing means for condensing the laser beam is changed during the half etching process, so The at least one taper angle is different from the taper angle of the other side wall.

  The invention of claim 11 is the printing mask manufacturing method of claim 9, wherein the aperture area of the aperture mask that partially shields the laser beam irradiated toward the substrate during the half-etching process is provided. By changing, the taper angle of at least one of the plurality of side walls is made different from the taper angle of the other side walls.

  A twelfth aspect of the present invention is the printing mask manufacturing method according to the ninth aspect, wherein the energy density per unit time of the center of the spot of the laser beam is changed during the half-etching process, so that a plurality of the side walls are formed. At least one of the taper angles is different from the taper angle of the other side wall.

  In these inventions, the printing mask is manufactured according to any one of the first and second aspects. And in invention which manufactures a printing mask by the structure of Claim 1, the shape of the through-hole by irradiating the laser for a half-etching process by performing a half-etching process prior to the drilling process of a through-hole Disturbance can be avoided. In addition, the half-etching process and the perforation process are performed so that the laser irradiation surface is reversed, so that the through-hole is widened toward the exit of the printing material. Therefore, it is possible to improve the printing material detachability from the inside of the hole as compared with the case where the through hole is processed into a tapered shape toward the outlet, and to suppress the remarkable disturbance of the printing pattern due to the poor printing material detachment property.

  Further, in the invention for manufacturing a printing mask according to the configuration of claim 2, the shape of the through-hole caused by irradiating the laser for half-etching by performing half-etching prior to the drilling of the through-hole Disturbance can be avoided. Further, if an extremely thin substrate having a thickness of about 50 to 75 [μm] is used as the base material, the printed pattern is hardly disturbed due to poor printing material removal. Therefore, by using an extremely thin base material, it is possible to suppress the disturbance of the printing pattern due to the poor printing material removal property. Furthermore, in the present invention, unlike the invention of claim 1, it is not necessary to perform the work performed when the substrate is turned over so that the laser irradiation surface is reversed in the subsequent process from half etching to drilling. . Therefore, for example, the relative position between the half-etched portion and each through-hole is shifted due to the relative positional deviation between the base material and the laser processing apparatus in the base material surface direction when turning over. It is also possible to avoid various problems caused by turning over, which can occur in the first invention.

  According to a third aspect of the present invention, a printing mask is manufactured according to the second aspect of the present invention. The edge on the printing material imprinting surface side of the half-etched portion is formed by using a condensing means having a relatively low resolution in the half-etching process. Smooth the part. As a result, it is possible to manufacture a printing mask that can reduce wear of the squeegee during printing or improve the scraping property of the printing material from the half-etched portion. On the other hand, the edge portion on the printing material printing surface side of the through hole is sharpened by using condensing means having a relatively high resolution in the drilling process. And thereby, the entrance of the printing material with respect to the through-hole can be narrowed, or the taper of the inner wall of the through-hole can be raised to improve the printing material removal property. Note that the lower the resolution, the lighter the taper of the side wall of the half-etched part or the through hole, the smoother the edge of the half-etched part or the through-hole. For the reason explained. That is, FIG. 27 is a graph showing the relationship between the energy density per unit time of the laser beam and the distance from the laser beam spot center. In the figure, the graph indicated by the solid line indicates the energy density per unit time of the laser beam condensed by the condensing means having a relatively low resolution. Moreover, the graph shown with a dotted line has shown the energy density per unit time of the laser beam condensed by the condensing means with comparatively high resolution. As shown in the figure, the energy density per unit time of the laser beam is maximum at the spot center. Then, it begins to become smaller than the maximum value at a point P at a certain distance from the center of the spot, and gradually decreases from the point P (hereinafter referred to as a descent start point P) toward the outer edge of the spot. Minimal. Here, the laser beam region from the spot center to the descent start point P is defined as the laser center portion. Further, a laser beam region from the descending start point P to the spot outer edge is defined as a laser outer edge. Then, in the base material region processed by the laser outer edge portion, the amount of digging down by laser irradiation gradually decreases from the spot center side toward the spot outer edge side, so that a taper is formed. As shown in the drawing, the descent start point P approaches the spot center as the resolution of the light collecting means decreases. As a result, the lower the resolution of the light collecting means, the gentler the taper of the side wall of the half-etched part or the through hole.

  According to a fourth aspect of the present invention, a printing mask is manufactured according to the structure of the first or second aspect of the invention, and the edge portion on the printing material printing surface side of the half-etched portion is formed by tapering the side wall of the half-etched portion. To smooth. As a result, it is possible to manufacture a printing mask that can reduce wear of the squeegee during printing or improve the scraping property of the printing material from the half-etched portion.

  In particular, in the fifth to eighth aspects of the invention, the half-etched portion can be collectively processed by performing the half-etching process using a laser beam having a spot area equal to or larger than the plane area of the half-etched portion. . This batch processing is a processing region expansion method in which a half-etched region is gradually expanded in the direction of the substrate surface while changing the laser irradiation region on the substrate in the direction of the substrate surface to form one half-etched portion. Is different. In forming one half-etched portion, the same beam spot is applied to the entire area of the half-etched portion, and the half-etched portion is formed at once without gradually expanding the laser irradiation region in the direction of the substrate surface. It is processing. In such collective processing, the half-etched portion can be processed more quickly than in the processing area expansion method.

  In particular, in the invention of claim 6, by setting the resolution of the condensing means, the above-mentioned laser outer edge portion in the laser light is made relatively large so that the side wall of the half-etched portion is tapered even in batch processing. You can turn on.

  In particular, in the invention of claim 7, the above-mentioned laser outer edge portion in the laser light is made relatively large by setting the aperture area of the aperture mask. Specifically, as described above, the energy density per unit time gradually decreases from the spot center side to the spot outer edge side at the laser outer edge portion. For this reason, when an aperture mask having a relatively small opening that shields all of the outer edge of the laser is used, the side walls of the half-etched part and the through hole are vertically cut without a taper. Further, when a relatively large opening that only partially shields the outer edge of the laser is used, the taper of the side wall becomes gentler as the opening area increases. The smaller the difference between the laser spot area and the aperture area of the aperture mask, the smaller the side wall taper. Therefore, the outer edge of the laser can be made relatively large by setting the aperture area of the aperture mask. And by making a laser outer edge part comparatively large, even if it is collective processing, the side wall of a half etching part can be tapered.

  In particular, in the invention of claim 8, the laser outer edge portion in the laser light is made relatively large by setting the energy density per unit time at the center of the spot of the laser light. Specifically, in the laser beam, the lowering start point P approaches the spot center as the energy density per unit time at the spot center decreases. In other words, the lower the energy density per unit time at the center of the spot, the larger the laser outer edge. For this reason, the laser outer edge can be made relatively large by setting the energy density per unit time at the center of the spot. And by making a laser outer edge part comparatively large, even if it is collective processing, the side wall of a half etching part can be tapered.

  Particularly, in the inventions of claims 9 to 12, for the reasons described below, there is a benefit that the wear of the squeegee during printing can be reduced and the scraping property of the printing material from the half-etched portion can be improved. Without reducing as much as possible, it is possible to avoid a situation where the taper of the side wall of the half-etched portion is connected to the through hole. That is, in the half-etched portion having a tapered side wall, the opening area at the upper end is larger than the bottom area at the lower end. In such a half-etched part, if a through hole is formed in a taper outside the bottom region, the depth of the through hole is made larger than that of the desired depth formed in the bottom region. End up. For this reason, the region where the through hole can be formed in the half-etched portion having the tapered side wall is only the bottom region without the taper. On the other hand, if the through hole is formed too close to the half-etched portion in the non-etched portion of the substrate, a part of the through-hole is connected to the taper of the half-etched portion. For this reason, the region where the through hole can be formed must be outside the opening of the half-etched portion. Then, even if the through hole of the non-etched part and the through hole of the half-etched part are formed as close as possible, it is necessary to separate them by at least the horizontal distance of the taper. However, depending on the print pattern, it may be necessary to bring both closer than the horizontal distance. In such a case, it is necessary to shorten the horizontal distance of the taper by making the angle of the taper steeper in order to avoid the situation where the through hole and the taper are connected and to bring them closer. However, if it shrinks, the edge of the half-etched portion is sharpened to reduce the squeegee wear, and the advantage that the printing material scraping property from the half-etched portion can be reduced. Therefore, in the inventions of claims 9 to 12, at least one taper angle of the plurality of side walls in the half-etched portion is made different from the taper angle of the other side wall. In such a half-etching process, the side wall located between the through hole in the half-etched part and the through-hole in the non-etched part, which needs to be formed very close to each other, has a taper angle that is considerably steep and penetrated. Avoid connection between hole and taper. On the other hand, with respect to the side wall located between the through hole in the half-etched part and the through-hole in the non-etched part that are adjacent to each other at a considerable distance, the taper angle is made gentle to smooth the edge. Accordingly, it is possible to avoid a situation in which the taper of the side wall of the half-etched portion and the through hole are connected without reducing the above-described profit as much as possible.

  In particular, in the invention of claim 10, the laser beam is orthogonal to the substrate surface when the outer edge of the half-etched portion is laser-processed by changing the resolution of the light collecting means during the half-etching process. The side wall of the half-etched portion can be tapered without performing a laborious operation such as irradiating with tilting from the direction.

  In particular, in the invention of claim 11, by changing the aperture area of the aperture during the half-etching process, when laser processing the outer edge of the half-etched portion, the laser beam is perpendicular to the substrate surface. Thus, the side wall of the half-etched portion can be tapered without performing a laborious work such as irradiating with a tilt.

  In particular, in the invention of claim 12, when the outer edge of the half-etched portion is laser-processed by changing the energy density per unit time at the center of the spot of the laser beam during the half-etching process, It is possible to taper the side wall of the half-etched portion without performing a time-consuming work of irradiating with a tilt from a direction orthogonal to the substrate surface.

  Therefore, according to the first to twelfth aspects of the present invention, the half-etching process is performed prior to the drilling of the through-hole, thereby avoiding the disorder of the shape of the through-hole due to the irradiation of the laser for the half-etching process. There is an excellent effect that can be done. In particular, according to the first aspect of the present invention, the printing material is more easily removed from the hole than when the through hole is processed into a tapered shape toward the outlet, and the printing pattern due to poor printing material removal is achieved. There is an excellent effect that it is possible to suppress the significant disturbance of. In particular, according to the invention of claim 2 or 3, by using an extremely thin substrate having a thickness of about 50 to 75 [μm] as a base material, it is possible to suppress the disturbance of the printing pattern due to poor printing material removal. There is an excellent effect that it becomes possible. Furthermore, there is also an excellent effect that various problems caused by punching after turning the substrate upside down after half-etching can be avoided. In particular, according to the invention of claim 3, it is possible to produce a printing mask that can reduce the wear of the squeegee during printing or improve the scraping property of the printing material from the half-etched portion. effective. Furthermore, there is an excellent effect that it is possible to manufacture a printing mask with further improved printing material removal property by narrowing the entrance of the printing material with respect to the through hole or increasing the taper of the inner wall of the through hole. In particular, according to the inventions of claims 4 to 12, it is possible to manufacture a printing mask that can reduce the wear of the squeegee during printing and improve the scraping property of the printing material from the half-etched portion. Has an excellent effect. In particular, according to the inventions 5 to 8, there is an excellent effect that the half-etched portion can be processed more quickly than in the case where the processing area expansion method is performed. In particular, according to the inventions of claims 6 to 8, there is an excellent effect that the side wall of the half-etched portion can be tapered even in batch processing. In particular, according to the inventions of claims 9 to 12, without reducing the benefit of reducing wear of the squeegee during printing or improving the scraping property of the printing material from the half-etched portion as much as possible, There is an excellent effect that it is possible to avoid a situation where the taper of the side wall of the half-etched portion and the through hole are connected. In particular, according to the inventions of claims 10 to 12, when performing laser processing on the outer edge of the half-etched portion, it is not necessary to perform laborious work such as irradiating the laser beam with a tilt from a direction orthogonal to the substrate surface. There is an excellent effect that the side wall of the half-etched portion can be tapered.

Hereinafter, an embodiment of a printing mask manufacturing method for manufacturing a printing mask for printing a bump electrode pattern made of cream solder on an electronic circuit board as a printing mask will be described.
First, a first embodiment to which the present invention is applied will be described. FIG. 6 is a schematic configuration diagram showing an excimer laser device used in the printing mask manufacturing method according to the first embodiment. This excimer laser device includes a workpiece mounting table 11, an XY table 12, an XY table driving system 13, a driving motor 14, a motor driving circuit 15, and the like. Further, a laser driving circuit 18, an excimer laser 17, a reflecting mirror 19, an aperture 20, a condensing lens 21 as a condensing means, an attenuator 30 and the like are provided.

  In the figure, a base material 2 made of plastic such as PET (polyethylene terephthalate) is placed on a work placement table 11 having a substantially horizontal work placement surface 11a. The workpiece mounting table 11 is disposed on an XY table 12 that can move the workpiece mounting surface 11a in the X direction that is the left-right direction in the drawing and the Y direction that is the depth direction in the drawing. Yes.

  The XY table 12 is driven in the XY direction by a drive motor 14 composed of a servo motor (or a stepping motor) via an XY table drive system 13 constituted by a ball shaft or a linear motor (not shown). Is done. The drive motor 14 is driven and controlled by a motor drive circuit 15, and the motor drive circuit 15 is controlled by a main controller (not shown).

  Moreover, the XY table 12 has the base material 2 placed thereon via a suction device. This suction device has a suction machine (not shown), a suction chamber sucked by the suction device, and numerous suction holes formed in the upper wall of the suction device, and the substrate 2 is placed on the upper wall. ing. And the base material 2 is attracted | sucked through innumerable suction holes from the suction chamber which becomes a negative pressure by suction with a suction machine. By this suction, the film-like substrate 2 is sucked and fixed in a suction chamber shape while maintaining flatness.

  The excimer laser 17 generates a laser beam having a processing frequency based on the laser drive circuit 18 for driving the laser based on a drive trigger having a predetermined frequency (usually 200 Hz). The emitted laser beam 17 a is adjusted by the attenuator 30 so that the beam energy density is suitable for processing the substrate 2. Then, the light path is appropriately changed by the reflecting mirror 19 so as to be incident substantially perpendicular to the processed surface of the substrate 2, and then the aperture 20 is transmitted. Further, the beam is condensed by the condenser lens 21 so that the beam diameter on the processed surface of the substrate 2 becomes a predetermined dimension, and then the beam irradiation position in the XY direction is adjusted by the XY table 12. The material 2 is reached and processed.

  FIG. 7 is a perspective view showing the substrate 2 used in the printing mask manufacturing method according to the first embodiment and the mask frame 5 that supports the substrate 2 while tensioning it. The printing mask obtained by excimer laser processing of the substrate 2 is used in the state of a printing mask member whose peripheral portion is bonded and fixed to the frame-like mask frame 5 at the time of printing. As a method for obtaining such a printing mask member, a method of bonding and fixing a printing mask manufactured by excimer laser processing to the mask frame 5 and excimer laser processing to the base material 2 which has been bonded and fixed to the mask frame 5 at first are performed. There is a method. Either method may be adopted, but in the present embodiment, the latter method will be described as an example.

  In the figure, a mask frame 5 is an aluminum square pipe assembled in a frame shape. In the base material 2 bonded and fixed to the lower surface of the mask frame 5 in the figure, the upper surface in the figure later becomes the squeegee surface 2a (printing material printing surface). Then, the surface opposite to this is a circuit contact surface 2b that is brought into close contact with an electronic circuit board as a printing medium during printing. In this printing mask manufacturing method, a PET sheet having a thickness of 150 [μm] is used as the substrate 2.

  Prior to excimer laser processing, as shown in FIG. 8, the operator first measures the reference position on the substrate 2 with the circuit contact surface 2 b on the upper side in the vertical direction from the end of the mask frame 5. Then, the reference mark M is marked at the reference position. Next, the print mask member is turned over so that the squeegee surface is directed upward in the vertical direction (the side facing the excimer laser device), and then set on the work mounting table (11) of the excimer laser device.

  FIG. 9 is an enlarged cross-sectional view showing the workpiece mounting table and the base material 2 of the printing mask member set on the workpiece mounting table. First, the substrate 2 is placed on the workpiece placement surface 11a of the workpiece placement table 11 in a state where the squeegee surface 2a is directed upward in the vertical direction in the drawing so that the squeegee surface 2a becomes a laser irradiation surface. The workpiece placement surface 11 a is the surface of a glass plate 11 b provided on the upper surface of the workpiece placement table 11. In addition to the glass plate 11b, the work mounting table 11 sucks air in the suction chamber 11c, a laser absorbing plate 11d fixed to the bottom of the suction chamber 11c, and a suction chamber 11c. It is equipped with a suction machine (not shown) that makes the pressure negative. The base material 2 placed on the glass plate 11b is sucked and fixed toward the glass plate 11b by being sucked through the plurality of suction holes 11e provided in the glass plate 11b.

  Thus, the operator who sucked and fixed the base material 2 performs the reference positioning operation. Specifically, the microscopic device is placed so that the fiducial mark (M) previously attached to the base material 2 enters the field of view of the microscopic device for reference positioning (not shown) provided in the excimer laser device. The XY table (12) is manually operated while being removed. When the reference mark (M) enters the field of view, the center position of the mark in the XY coordinates in the field of view is read and stored as the reference position in the main controller of the excimer laser device. The main control unit controls the base member 2 to perform laser processing while controlling the movement of the XY table (12) with reference to the reference position.

  When the reference alignment operation is completed, half etching processing by excimer laser processing is performed based on half etching pattern data stored in advance in the main control of the excimer laser device. As a result, as shown in FIGS. 10 and 11, the laser shot adjusted to the irradiation time and intensity so as not to penetrate the entire thickness of the substrate 2 and the movement in the XY direction are continuously performed. Then, the ablation process of the half-etched portion 3 is performed on the base material 2. In addition, the code | symbol L in the figure has shown the excimer laser beam.

  When the half-etching process is finished, the operator stops the above-described suction machine and then removes the printing mask member from the mounting table 11. Then, as shown in FIG. 12, a plastic film 6 having the same depth and planar dimensions is inserted and pasted into the half-etched portion 3 formed by the half-etching process. Next, after the printing mask member (base material 2 + mask frame) is turned over, it is set on the work table 11 again. Then, the reference position alignment is performed by the same operation as that described above. At this time, the suction device is operated prior to the reference position alignment. However, as shown in FIG. 13, since the plastic film 6 is pasted in the half-etched portion 3, the half-etched portion 3 is moved along with the suction. The situation of bending toward the glass plate 11b does not occur. Therefore, in the subsequent drilling process, it is possible to avoid the disorder of the processed shape of the through hole caused by bending the half-etched portion 3 by the suction force for suction fixation.

  When the second reference positioning operation is completed, the excimer laser processing is performed on the basis of the drilling pattern data stored in advance in the main control of the excimer laser device. Thereby, as shown in FIGS. 14 and 15, the laser shot and the movement in the XY direction are continuously performed, and a plurality of penetrations are made in the half-etched portion 3 and the non-half-etched portion of the substrate 2. The hole 4 is ablated. At this time, the excimer laser light L transmitted through the base material 2 is transmitted through the glass plate 11b and then further reaches the glass plate 11b. This is the laser absorption plate 11d provided on the bottom surface of the suction chamber 11c. To be absorbed. Therefore, the situation that the workpiece mounting table 11 is processed by the excimer laser beam L does not occur. Further, when the through-hole 4 is processed, a laser for half-etching is irradiated by irradiating the base material 2 on which the half-etched portion 3 is first formed with an excimer laser for through-processing. It is possible to avoid the disorder of the shape of the through-hole 4 due to this. The through-hole 4 is processed in a shape that becomes wider from the squeegee surface 2a side toward the circuit contact surface 2b side. After processing the half-etching portion 3, the base material 2 (printing mask member) is turned over, and the through-hole 4 having such a shape is formed by irradiating laser from the opposite surface side (circuit contact surface 2b side) to the half-etching portion 3. Can be formed.

  In addition, after completion | finish of a punching process, the plastic film 6 stuck on the half etching part 3 is peeled, and the printing mask in which the half etching part 3 and the several through-hole 4 were formed is obtained.

  FIG. 16 is an enlarged cross-sectional view showing a state of bump electrode pattern printing using the printing mask 1 manufactured by the printing mask manufacturing method. As shown in the drawing, the printing mask 1 manufactured by the present printing mask manufacturing method has a through-hole 4 that is wide toward the outlet of the cream solder 60 when the plate is separated, so that it is narrow toward the outlet. Compared with the through-hole of the shape, the solder removability is improved. As a result, it is possible to suppress a significant disorder of the bump electrode pattern due to poor solderability.

Next, a second embodiment of a printing mask manufacturing method to which the present invention is applied will be described.
FIG. 17 is a schematic configuration diagram illustrating an excimer laser device used in the printing mask manufacturing method according to the second embodiment. The configuration is almost the same as that shown in FIG. 6 except for the following points. That is, a laser moving means 27 for moving the excimer laser in the Z-axis direction which is the vertical direction in the figure is provided. Another difference is that a lens switching means 26 is provided for switching the condensing lens to be transmitted by the excimer laser after passing through the aperture 20 between the first condensing lens 22 and the second condensing lens 23. The lens switching unit 26 switches the lens positioned in the optical path of the excimer laser by rotating the support 24 supporting the two lenses about the rotation shaft 25.

  The first condenser lens 22 is used for half-etching and has a relatively low resolution. The second condenser lens 23 is used for perforation and is a lens having a relatively high resolution. An example of the first condenser lens 22 is one having a resolution of 20 [μm] and a focal length f150. An example of the second condenser lens 23 is one having a resolution of 7 [μm] and a focal length f120. For example, it can be adjusted by the numerical aperture NA of the lens.

  Also in the printing mask manufacturing method according to the second embodiment, excimer laser processing is performed on the base material (2) bonded and fixed to the mask frame (5). The base material (2) has a thickness of 75 [μm. ] PET sheet is used. It is half the thickness of the substrate (2) used in the printing mask manufacturing method according to the first embodiment. Then, in the same manner as in the printing mask manufacturing method according to the first embodiment, after the reference mark (M) is written on the base material (2), the print mask member (base material + mask frame) is placed on the workpiece mounting table (11). Set on top and fix by suction.

  Next, in the same manner as the printing mask manufacturing method according to the first embodiment, after performing the reference positioning operation, the base material 2 is half-etched. At this time, the first condenser lens 22 is used as the condenser lens. As shown in FIG. 18, the first condenser lens 22 having a relatively low resolution performs ablation processing to smooth the edge on the laser irradiation surface side (squeegee surface 2a side). Therefore, the half etching process is performed by the first condenser lens 22 having a relatively low resolution shown in FIG. 17 to reduce the wear of the squeegee at the time of printing, or the cream solder scraping from the half etching unit 3. It is possible to manufacture a printing mask that can improve the removability.

  When the half etching process is finished, the condenser lens is switched from the first condenser lens 22 to the second condenser lens 23 as shown in FIG. 19 without stopping the suction by the suction machine. Further, the focal length of the second condenser lens 23 is adjusted by operating the laser moving means 27 shown in FIG. When the focal length is adjusted, the substrate 2 (printing mask member) is not turned over, and the substrate 2 is irradiated with laser from the squeegee surface side as in the case of the half-etching process. ) Is ablated. As shown in FIG. 20, the second condenser lens 23 having a relatively high resolution performs ablation processing to smooth the edge on the laser irradiation surface side (squeegee surface 2a side). Accordingly, the through hole 4 having a sharp edge on the squeegee surface 2a side as shown in FIG. 20 is obtained by performing the drilling process with the second condenser lens 23 having a relatively low resolution shown in FIG. Can be formed.

  FIG. 21 is an enlarged cross-sectional view showing a print mask manufactured by the print mask manufacturing method according to the second embodiment. As described above, in this printing mask manufacturing method, both the half etching process and the perforating process are performed by irradiating the substrate 2 with laser from the squeegee surface 2a side (printing material entrance side). As a result, the through-hole 4 has been processed into a tapered shape toward the circuit contact surface 2b side (printing material outlet side). However, since an extremely thin material of 75 [μm] is used as the substrate 2, the difference in diameter between the squeegee surface 2a side and the circuit contact surface 2b side is slight as shown in the figure. Therefore, as compared with the case where a substrate 2 having a thickness similar to the conventional one such as 150 [μm] is used, it is possible to suppress the disorder of the printing pattern due to the poor soldering ability.

  Further, in the present printing mask manufacturing method, unlike the first embodiment, the work performed when the substrate 2 is turned over to reverse the laser irradiation surface in the subsequent steps from the half etching process to the drilling process. Not performed. Therefore, it is possible to avoid a situation in which the relative position between the half-etched portion (3) and each through hole (4) is shifted due to causing a shift in reference position alignment when turning over. Furthermore, in order to avoid a situation in which the half-etched portion (3) is bent due to suction fixation at the time of drilling, a troublesome work such as attaching a plastic film (6) in the half-etched portion (3). There is no need to do.

  Next, a third embodiment of a printing mask manufacturing method to which the present invention is applied will be described. In this printing mask manufacturing method, the base material 2 is turned over after half-etching in the same manner as in the first embodiment, and then punching is performed, or the base material 2 is not turned over as in the second embodiment. Either drilling is performed or any method is used. That is, it is the same as the first embodiment or the second embodiment in that the base material 2 is turned over and not turned over. The difference from the first embodiment and the second embodiment resides in the half etching method. Specifically, in the printing mask manufacturing method according to the first embodiment or the second embodiment, the half-etched portion 3 is processed by half-etching using a processing area expansion method. As described above, this processing area enlargement method means that the half-etched area is gradually moved in the substrate surface direction while the laser irradiation area on the substrate 2 is changed in the substrate surface direction by the movement of the XY table 12. In this method, one half-etched portion 3 is formed by spreading. On the other hand, in the printing mask manufacturing method according to the third embodiment, the half-etched portion is irradiated without irradiating the same beam spot to the entire region of the half-etched portion 3 and gradually expanding the laser-irradiated region in the substrate surface direction. 3 is formed at a stretch. The half etching part 3 is processed collectively.

  FIG. 22 is an enlarged configuration diagram showing the base material 2 on which the half-etched portion 3 is processed by the printing mask manufacturing method, together with the mounting table 11. FIG. 23 is an enlarged configuration diagram showing the base 2 on which the half-etched portion 3 has been processed by the printing mask manufacturing method, together with the mounting table 11. As shown in both figures, in this printing mask manufacturing method, the half etching unit 3 is moved by one laser spot without moving the mounting table 11 (XY table 12) during the laser processing of the half etching unit 3. Is processed at once. That is, the same beam spot is irradiated to the entire region of the half-etched portion 3. In such collective processing, the half-etched portion 3 can be formed more quickly than the half-etching processing of the processing area expansion method in the first embodiment or the second embodiment.

  Even when the half-etching unit 3 is collectively processed, the side wall of the half-etching unit 3 can be tapered by setting the resolution of a condensing lens (not shown) that collects the laser light L. The reason is as described above with reference to FIG. Therefore, in this printing mask manufacturing method, when the half-etched portion 3 is collectively processed, the edge of the half-etched portion 3 is smoothed by using a condensing lens having a relatively low resolution. However, it is not preferable to use a condensing lens with the same resolution as in the half-etching process when drilling the through-hole, because the side wall of the through-hole is also greatly tapered. In particular, when drilling is performed without turning the substrate 2 upside down after half-etching, a large taper on the side wall of the through hole results in a print mask that is likely to be disturbed by an electrode pattern due to poor solderability. Therefore, also in this printing mask manufacturing method, the excimer laser apparatus previously shown in FIG. 17 is used. Then, while the first condenser lens 22 is used in the half etching process, the second condenser lens 23 having a higher resolution is used in the drilling process to taper the side wall of the through hole. Make it as steep as possible.

  In the present printing mask manufacturing method, the following can be achieved by tapering the side wall of the half-etched portion 3. That is, it is possible to manufacture a printing mask that can reduce the wear of the squeegee during printing or improve the cream solder scraping property from the half-etched portion. Moreover, even if it is batch processing, the side wall of the half-etched portion 3 can be tapered.

  FIG. 24 is a schematic configuration diagram showing an excimer laser device used in a modification of the printing mask manufacturing method. The configuration is almost the same as that shown in FIG. 17 except for the following points. That is, no lens switching means for switching the condenser lens is provided. Instead, opening switching means for switching the opening of the aperture 20 is provided. This aperture switching means switches the aperture positioned in the optical path of the laser beam L by rotating the aperture 20 having the large aperture 20a and the small aperture 20b having a smaller aperture area around the rotation axis 20c. .

  The large opening 20a is used for half-etching. Further, the small opening 20b having a smaller opening area is used for drilling. As the aperture 20 having a larger aperture area is used, the side wall taper of the half-etched portion is made gentler and the edge of the half-etched portion becomes smoother as in the case of using a condenser lens with a low resolution. Can do. Therefore, in this modification, when the half-etched portion is collectively processed, the large opening 20a of the aperture 20 is used to smooth the edge of the half-etched portion. On the other hand, when drilling, the small opening 20b is used to make the side wall taper of the through hole as steep as possible.

  Even in the case of an excimer laser device that is not provided with a lens switching unit or an aperture switching unit, the same effects as those when the condenser lens and the aperture are switched can be obtained as follows. That is, in the half-etching process, the energy density per unit time of the laser beam spot center per unit time is made lower than in the drilling process, thereby making the paper on the side wall of the half-etched part gentler than the through-hole.

  Next, a fourth embodiment of a printing mask manufacturing method to which the present invention is applied will be described. Also in this printing mask manufacturing method, it is the same as that of 1st Embodiment or 2nd Embodiment that the base material 2 is turned over before perforation processing and it does not turn over. Further, similarly to the first embodiment and the second embodiment, the half-etched portion is processed by the processing region enlargement method. The difference from the first and second embodiments is that the taper angle is made different between at least one of the plurality of side walls of the half-etched portion and the others. Specifically, in the first embodiment and the second embodiment, the plurality of sidewall tapers constituting the outer edge portion of the half-etched portion are all processed at the same angle. On the other hand, in this printing mask manufacturing method, the taper angle is varied.

  FIG. 25 is an enlarged cross-sectional view showing a print mask manufactured without using the present print mask manufacturing method. In this figure, the printing mask 1 has two through holes, a non-etched part first through hole 4A and a non-etched part second through hole 4D, in a non-etched part around the half-etched part 3. Further, the half-etched portion 3 has two through-holes, that is, an etched portion first through-hole 4B and an etched portion second through-hole 4C. The non-etched portion first through hole 4A and the etched portion first through hole 4B are adjacent to each other via the first side wall 3a of the half-etched portion 3. In addition, the non-etched portion second through hole 4D and the etched portion second through hole 4C are adjacent to each other via the second side wall 3b of the half-etched portion 3.

  The non-etched portion first through hole 4A and the etched portion first through hole 4B are adjacent to each other with a relatively long distance. On the other hand, the non-etched part second through hole 4D and the etched part second through hole 4C are separated from each other only by a small distance. The distance L1 between the gaps formed between the two is, for example, only a few tens [μm].

  As the taper angle of the plurality of side walls constituting the outer edge of the half-etched portion 3 becomes smoother, the edges become smoother to reduce wear of the squeegee, and the cream solder scraping property from the half-etched portion is improved. can do. On the other hand, the horizontal length becomes large. In the illustrated example, the horizontal length of the second side wall 3b is set between the non-etched portion second through hole 4D and the etched portion second through hole 4C due to the gradual taper angle. Is bigger than. As a result, the non-etched portion second through-hole 4D is connected to the taper of the second side wall 3b of the half-etched portion 3. The non-etched part second through hole 4D greatly disturbs the shape of the bump electrode made of cream solder. In order to avoid the connection between the non-etched portion second through-hole 4D and the taper, if the position of the half-etched portion 3 with respect to the base material 2 is shifted to the right in the figure, this time, the etched-portion second through-hole 4C. Is connected to the taper of the second side wall 3b.

FIG. 26 is an enlarged cross-sectional view showing a print mask manufactured by the present print mask manufacturing method. In the same figure, the formation positions of the through holes and the half-etched portion 3 in the printing mask 1 are the same as those shown in FIG. The printing mask 1 is different from that shown in FIG. 25 in the taper angle of the second side wall 3b. In Figure 26, a second side wall 3b which is interposed between the non-etched portion second through hole 4D and etched portion second through hole 4C is taper angle theta ₂ becomes considerably steeper than that shown in FIG. 25 Yes. As a result, the horizontal length is shorter than that shown in FIG. And the length is smaller than the gap | interval L1 required between non-etching part 2nd through-hole 4D and etching part 2nd through-hole 4C. For this reason, as shown in FIG. 26, without connecting the non-etched portion second through hole 4D and the etched portion second through hole 4C to the taper of the second side wall 3b, the second side wall 3b having a taper angle θ ₂ therebetween. Can be interposed.

On the other hand, the first side wall 3a which is interposed between the non-etched portion first through-holes 4A and etching portion first through-hole 4B adjacent to each other at a rather long distance from each other, the taper angle theta _1, in FIG. 25 Like the thing, it is relatively gentle. Thereby, wear of the squeegee is reduced or the cream solder scraping property from the half-etched portion 3 is improved. Although not shown, all of the side wall excluding the second side wall 3b of the plurality of side walls constituting the outer edge of the half-etched portion 3, and the taper angle theta ₁ similar to the first side wall 3a Yes. In other words, in the illustrated printing mask 1, only the second side wall 3b has a smaller taper angle than the other side walls.

  A specific method of making the taper angle different between the second side wall 3b and the other side wall may be performed by changing the resolution of the condenser lens during the half etching process of the processing area enlargement method. Alternatively, the aperture area of the aperture or the energy density per unit time of the laser beam spot center may be changed. More specifically, when processing the vicinity of the second side wall 3b, a condensing lens having a relatively high resolution, an aperture mask having a relatively small area, or a relatively high energy density per unit time of the spot center. Use high laser light. On the other hand, when processing the vicinity of other side walls, a condensing lens with a relatively low resolution, an aperture mask with a relatively large aperture, or a laser with a relatively low energy density per unit time of the spot center Use light. In order to change the resolution of the condenser lens and the aperture area of the aperture, the excimer laser device shown in FIGS. 17 and 24 may be used.

  In the printing mask manufacturing method according to the fourth embodiment as described above, it is possible to reduce the wear of the squeegee at the time of printing or to improve the cream solder scraping property from the half-etched portion 3. Without being reduced as much as possible, it is possible to avoid a situation where the second side wall 3b is connected to the non-etched portion second through hole 4D or the etched portion second through hole 4C.

  So far, an example of manufacturing a printing mask for printing a bump electrode pattern has been described. However, the present invention can also be applied to a printing mask manufacturing method for manufacturing a printing mask for printing other printing patterns, for example, for image printing.

Sectional drawing which shows the printing mask in which the half etching part and the through-hole were formed. Sectional drawing which shows the cream solder imprinting process in the printing method using the printing mask. Sectional drawing which shows the plate separation process in the printing method using the printing mask. Sectional drawing which shows the printing mask obtained by laser-irradiating a half etching process and a perforation process from the same surface side with respect to a base material. Sectional drawing which shows the plate separation process in the printing method using the printing mask. The schematic block diagram which shows the excimer laser apparatus used for the printing mask manufacturing method of 1st Embodiment. The perspective view which shows the base material used for the printing mask manufacturing method, and the mask frame which supports this, tensioning. The perspective view which shows the same base material with which the reference mark was attached | subjected, and the same mask frame which supports this. The expanded sectional view which shows the same base material mounted in the workpiece mounting base of the same excimer laser apparatus. The expanded sectional view which shows the same base material which the half etching part began to process. The expanded sectional view which shows the same base material which the process of the half etching part was complete | finished. The expanded sectional view explaining the plastic film sticking operation | work to the half-etching part of the base material. The expanded sectional view which shows the same base material fixed by suction on the workpiece mounting base. The expanded sectional view which shows the same base material which has begun drilling. The expanded sectional view which shows the printing mask obtained by completion | finish of the punching process with respect to the same base material. The expanded sectional view which shows the plate separation process in the printing method using the printing mask. The schematic block diagram which shows the excimer laser apparatus used for the printing mask manufacturing method of 2nd Embodiment. The expanded sectional view which shows the base material in which the half etching part was formed by the ablation process by the same excimer laser apparatus using the 1st condensing lens. The schematic block diagram which shows the lens switching means of the same excimer laser apparatus which switched the condensing lens from the 1st condensing lens to the 2nd condensing lens. The expanded sectional view which shows the same base material in which the several through-hole was formed by the ablation process by the same excimer laser apparatus using a 2nd condensing lens. The expanded sectional view which shows the printing mask manufactured with the printing mask manufacturing method. The expanded block diagram which shows the base material with which the half etching part was processed by the printing mask manufacturing method which concerns on 3rd Embodiment with a mounting base. The expanded block diagram which shows the same base material with which the half etching part began to be processed with a mounting base. The schematic block diagram which shows the excimer laser apparatus used with the modification of the printing mask manufacturing method. The expanded sectional view which shows the printing mask manufactured without being based on the printing mask manufacturing method concerning 4th Embodiment. The expanded sectional view which shows the printing mask manufactured by the printing mask manufacturing method concerning 4th Embodiment. The graph which shows the relationship between the energy density per unit time of a laser beam, and the distance from the spot center of a laser beam.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Print mask 2 Base material 2a Squeegee surface 2b Circuit contact surface 3 Half etching part 4 Through-hole 22 1st condensing lens (lower resolution lens)
23 Second condenser lens (Lens with higher resolution)
L excimer laser light

Claims (12)

In a printing mask manufacturing method for forming a printing pattern consisting of at least a plurality of through holes by applying half etching processing and drilling processing by laser irradiation to a substrate,
A printing mask manufacturing method, comprising: performing the perforating process by irradiating the substrate with a laser beam from the side opposite to the half etching process after the half etching process. In a printing mask manufacturing method for forming a printing pattern consisting of at least a plurality of through holes by applying half etching processing and drilling processing by laser irradiation to a substrate,
A printing mask manufacturing method, comprising: performing the perforating process by irradiating the base material with a laser beam from the same surface side as the half etching process after the half etching process. In the printing mask manufacturing method of Claim 2,
In the punching process, a laser beam is condensed by a condensing means having a higher resolution than that used in the half-etching process. In the printing mask manufacturing method of Claim 1, 2, or 3,
A printing mask manufacturing method comprising performing the half etching process so as to taper a side wall of a half etching part formed on the base material. In the printing mask manufacturing method of Claim 4,
A printing mask manufacturing method, wherein the half etching process is performed by irradiating the base material with a laser beam having a spot area equal to or larger than a plane area of the half etching portion. In the printing mask manufacturing method of Claim 5,
A printing mask manufacturing method, wherein the side wall is tapered by setting the resolution of a condensing means for condensing the laser light. In the printing mask manufacturing method of Claim 5,
A printing mask manufacturing method, wherein the side wall is tapered by setting an opening area of an aperture mask that partially shields laser light irradiated toward the substrate. In the printing mask manufacturing method of Claim 5,
A printing mask manufacturing method, wherein the side wall is tapered by setting the energy density per unit time of the laser beam spot center. In the printing mask manufacturing method of Claim 4,
During the half-etching process, the substrate is irradiated with laser light having a spot area smaller than the plane area of the half-etched portion, and the half-etched region is changed while changing the laser irradiation region to the substrate in the substrate surface direction Are gradually expanded in the substrate surface direction to form the half-etched portion, and at least one taper angle of the plurality of side walls in the half-etched portion is made different from the taper angle of the other side wall. The printing mask manufacturing method characterized by these. In the printing mask manufacturing method of Claim 9,
During the half etching process, by changing the resolution of the condensing means for condensing the laser light, the taper angle of at least one of the plurality of side walls is different from the taper angle of the other side walls. A printing mask manufacturing method characterized by comprising: In the printing mask manufacturing method of Claim 9,
During the half-etching process, by changing an opening area of an aperture mask that partially blocks the laser beam irradiated toward the base material, at least one taper angle of the plurality of side walls is changed. And a method of manufacturing a printing mask, wherein the taper angle of the other side wall is made different. In the printing mask manufacturing method of Claim 9,
During the half-etching process, by changing the energy density per unit time of the laser beam spot center, at least one taper angle of the plurality of side walls and the taper angle of the other side walls are obtained. A method for producing a printing mask, characterized by differentiating.

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