JP2010105394A - Screen plate, method for manufacturing the same, and method for forming bump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a screen plate further uniformizing the height of bumps formed by discharge of paste in the plate, a method for manufacturing the same, and a method for forming the bumps using the screen plate. <P>SOLUTION: This screen plate includes a first region with a plurality of pits bored for discharging the paste, in which the average diameter of the pits is a first prescribed size, and a second region positioned next to the first one, with a plurality of pits bored for discharging the paste, in which the average diameter of the pits is a second prescribed size different from the first one. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a screen plate having pits for discharging a paste, a method for manufacturing the same, and a bump forming method using the screen plate. In particular, the height of a bump formed by discharging a paste is set to a screen. The present invention relates to a screen plate suitable for uniformizing within a plate, a method for producing the same, and a bump forming method using the screen plate.

  In order to form a fine structure on an object surface, a technique using screen printing is used in various situations. One of them is to form conductive bumps as fine structures on a wiring board or metal foil. The conductive bumps printed and formed by such a method have a sharp tip, so that they can easily penetrate the semi-cured insulating plate (prepreg) and serve as a fine interlayer connection conductor between the wiring layers that penetrate the insulating plate. Can be used.

  The formation of the conductive bumps requires a certain height to penetrate the insulating plate. Further, the formation height is required to be uniform. If the uniformity is poor, the probability of occurrence of conductive bumps that are incompletely penetrated into the insulation board will increase, or conductive bumps that are higher than the surrounding will crack during lamination pressurization, and small pieces will remain, resulting in wiring boards. This is because the manufacturing yield of the product deteriorates.

  In addition to the local non-uniformity at various points in the screen plate as described above, the non-uniformity in the formation height includes a general non-uniformity due to factors in principle of screen printing. In the direction in which the squeegee moves, there is a possibility that unevenness occurs in the bump formation height due to changes in the angle and speed at which the screen plate moves away from the surface of the printing material at each position in the movement direction. Further, in the longitudinal direction of the squeegee, there is a possibility that nonuniformity occurs in the bump formation height due to the influence of squeegee deflection, wear difference, or the like.

  On the other hand, in general, in a wiring board having fine interlayer connection conductors, a method of manufacturing a plurality of wiring boards on a large insulating board at the same time is often employed in order to improve productivity. In such a case, the formation of conductive bumps by screen printing is preferable as an efficient formation of an interlayer connection conductor. However, a problem arises in that conductive bumps are formed at a uniform height on each of the plurality of wiring boards. That is, in such a case, global bump height non-uniformity also deteriorates the manufacturing yield as a wiring board.

  Although the screen printing is different from the screen printing for forming conductive bumps in the conventional technology of screen printing, for example, there are those described in Patent Documents 1 to 5 below. Among these, the screen printing disclosed in Patent Documents 1 to 4 relates to uniform printing and application of a solder paste as a paste-like object. None of these are reminiscent of a screen version as disclosed herein.

  Further, the screen printing disclosed in Patent Document 5 relates to screen printing of a phosphor paste in display panel manufacture. This screen printing uses a screen plate in which a formation pattern is patterned on a mesh with an emulsion, and is not printing using a screen plate with pits formed therein. In addition, there is a description that the aperture ratio by patterning is different in each region set in the screen plate, but there is no description up to a specific and systematic design method related thereto.

JP-A-1-306287 JP-A-6-92054 JP-A-7-115265 Japanese Utility Model Publication No. 62-189156 JP 2004-32245 A

  The present invention has been made in consideration of the above-described circumstances. In a screen plate having pits for discharging a paste, a manufacturing method thereof, and a bump forming method using the screen plate, the paste is discharged by discharging the paste. It is an object of the present invention to provide a screen plate capable of making the height of bumps to be formed more uniform within the screen plate, a method for producing the same, and a bump forming method using the screen plate.

  In order to solve the above-described problem, the screen plate according to one aspect of the present invention includes a first plate in which a plurality of pits for discharging a paste are formed, and an average diameter of the plurality of pits is a first predetermined size. And a region located next to the first region, and a plurality of pits for discharging the paste are formed, and an average diameter of the plurality of pits is different from the first predetermined size. And a second region having a second predetermined size.

  That is, in this screen plate, the average diameters of a plurality of pits drilled in the first and second regions which are adjacent to each other are different. That is, the average diameter of the pits is different between regions so as to overcome the general bump height non-uniformity due to the principle of screen printing. In general, if the pit diameter is large, the amount of paste filled in the pit increases, so the bump height formed is higher. On the other hand, if the pit diameter is small, the amount of paste filled in the pit decreases, the bump height decreases. Will be lower. This general property is exploited to improve global bump height non-uniformity due to screen printing principles.

  The method for producing a screen plate according to another aspect of the present invention includes a step of setting n (n is an integer of 2 or more) regions in the horizontal direction or the vertical direction in a screen plate having a large number of pits. And a step of printing and forming bumps on the surface of the printed material using the screen plate, and a height of each of the bumps formed on the surface of the printed material or a bump formed on the surface of the printed material From the step of measuring the height of each sampled bump, the step of estimating the average value of the bump height for each of the n regions, and the average value of the n regions Identifying a function describing a relationship between the horizontal or vertical position x and the bump height h in the screen plate using a least square method, and the bump height h with respect to the horizontal or vertical position x in the function The step of obtaining a correction coefficient CF (x) at an arbitrary horizontal or vertical position x, which becomes smaller as the bump height h becomes larger and becomes smaller as the bump height h becomes larger, and the correction coefficient CF (x) And a step of obtaining a desired diameter value of each of the pits to be possessed for any screen plate, and a step of drilling pits in the plate member based on the desired diameter value. It is characterized by.

  That is, in this method, bumps are actually printed and formed on the surface of the substrate using a screen plate, and the height is measured. Then, an average value of the bump height is estimated in each of the n regions, and the bump height h at the position x is identified as a function of x by using the least square method so as to match the average value. Further, in accordance with the change of the bump height h with respect to the position x in this function, a correction coefficient at an arbitrary horizontal or vertical position x that is smaller as the bump height h is larger and larger as the bump height h is smaller is obtained. Then, using this correction coefficient, the value of the diameter of each pit that should be present is obtained for an arbitrary screen plate, and thereby pits are formed in the plate member. According to this, depending on the position of the pit in the screen plate, the diameter is drilled so as to make the height formed as a bump uniform.

  A bump forming method according to still another aspect of the present invention includes a step of setting n (n is an integer of 2 or more) regions in a horizontal direction or a vertical direction on a screen plate having a large number of pits. , A step of printing and forming bumps on the surface of the substrate using the screen plate, and a sampling of the heights of the bumps formed on the surface of the substrate or the bumps formed on the surface of the substrate A step of measuring each of the heights of some of the bumps, a step of estimating an average value of the height of the bump for each of the n regions, and the average value of the n regions, Identifying a function describing the relationship between the horizontal or vertical position x and the bump height h in the screen plate using a least square method, and changing the bump height h with respect to the horizontal or vertical position x in the function. Accordingly, a step of obtaining a correction coefficient CF (x) at an arbitrary horizontal or vertical position x, which is smaller as the bump height h is larger and larger as the bump height h is smaller, and the correction coefficient CF (x) is Utilized, it was obtained through a step of obtaining a desired diameter value of each desired pit for an arbitrary screen plate and a step of drilling pits in the plate member based on the desired diameter value. A screen plate is attached to a printing machine, a paste-like object is supplied onto the screen plate, and a squeegee is pressed onto the screen plate to bring the screen plate into linear contact with the surface of the printing material. By proceeding with the squeegee, the paste object is ejected onto the surface of the substrate through the pits of the screen plate to form bumps of the paste object. Characterized in that it.

  This bump forming method is a forming method performed using the screen plate obtained by the above-described method for manufacturing a screen plate.

  According to the present invention, there are provided a screen plate capable of making the height of bumps formed by discharging a paste more uniform in a screen plate, a manufacturing method thereof, and a bump forming method using the screen plate. Can do.

The flowchart which shows an example of the correction coefficient acquisition method of the screen plate pit diameter for obtaining the screen plate concerning one Embodiment of this invention. The block diagram which shows the example of arrangement | positioning of each area | region taken on the screen version. FIG. 5 is a layout view showing positions of relatively high bumps among bumps formed by a certain uncorrected screen plate. FIG. 4 is a layout view showing positions of relatively low height bumps formed by the same uncorrected screen plate as in FIG. 3. The graph explaining adjustment of a correction coefficient. FIG. 3 is a layout view showing positions of relatively high bumps formed by a screen plate having a corrected pit diameter. FIG. 7 is a layout view showing positions of bumps formed by the same screen plate as in FIG. 6 and having a relatively low height.

  As an embodiment of the present invention, a plurality of pits for ejecting paste are formed in an area located next to the second area on the side opposite to the first area. And a third region having a third predetermined size different from the second predetermined size. This is an increase in the number of areas to three, and according to this, the screen version is more sensitive.

  Here, the first region, the second region, and the third region may be adjacent to each other in the vertical direction. The vertical direction corresponds to, for example, the longitudinal direction of the squeegee, and can cause unevenness in bump formation height due to the influence of squeegee deflection, wear difference, or the like. Therefore, if the first, second, and third regions are regions adjacent in the vertical direction, this non-uniformity can be improved.

  Here, the average diameter of the plurality of pits in the second area is larger than both the average diameter of the plurality of pits in the first area and the average diameter of the plurality of pits in the third area. It can be. This is an example, but such a pit diameter is often preferable as a symptomatic response in an actual screen version.

  As an embodiment, the first region and the second region can be regions adjacent in the horizontal direction. The horizontal direction corresponds to, for example, the direction in which the squeegee moves, and can cause unevenness in the bump formation height due to changes in the angle at which the screen moves away from the surface of the substrate at each position in the movement direction. Therefore, if the first region and the second region are regions adjacent in the lateral direction, this non-uniformity can be improved.

  Further, the first region, the second region, and the third region may be adjacent to each other in the horizontal direction. In this case, the number of areas is increased to 3 in the horizontal direction. According to this, the screen version is more delicate than the case where the number of areas is two.

  Here, the average diameter of the plurality of pits in the first region is smaller than the average diameter of the plurality of pits in the second region, and the average diameter of the plurality of pits in the second region is the third diameter. It can be smaller than the average diameter of the plurality of pits in the region. This is an example, but such a pit diameter is often preferable as a symptomatic response in an actual screen version.

  As an embodiment, the diameters of the plurality of pits drilled in the first region are numerically distributed in a first predetermined width, and the plurality of pits drilled in the second region The pit diameters may be distributed in a second predetermined width as numerical values. The diameters of the plurality of pits drilled in the first region are numerically distributed in a first predetermined width, and the diameters of the plurality of pits drilled in the second region Is distributed in a second predetermined width as a numerical value, and the diameters of the plurality of pits drilled in the third region are distributed in a third predetermined width as a numerical value. You can also These mean that the diameter of the pit is changed within each region. That is, in order to make the height of the formed bumps uniform, the screen plate is more delicate.

  Further, as an embodiment as a method for producing a screen plate, the function may be an algebraic function of an order of 1 to n-1. It is very practical to use such an algebraic function as the function.

  Based on the above, embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a flowchart showing an example of a screen plate pit diameter correction coefficient acquisition method for obtaining a screen plate according to an embodiment of the present invention. Hereinafter, this method will be described with reference to FIG. 1 and other drawings (FIGS. 2 to 7). The correction coefficient obtained in this way is used to determine the value of the desired diameter of each pit that should be present for an arbitrary screen plate, and the pits are drilled into the plate member based on the value of the desired diameter. For example, a screen plate according to an embodiment of the present invention can be manufactured.

  First, bumps are printed and formed on the surface of the substrate to be printed using a screen plate that is not corrected for the pit diameter (= having the same pit as the nominal diameter) (step 11). The substrate to be printed is an insulating plate having a metal foil (copper foil) or a patterned metal foil, similar to that used in a normal wiring board manufacturing method. The paste used as the basis of the bump is, for example, a mixture of fine metal particles (silver, gold, copper, solder, etc.) in a paste-like resin and a volatile solvent mixed therein. The position of each pit may be a position corresponding to the actually produced wiring board, or may be a position specially set for carrying out this method.

  The procedure for printing and forming bumps on the surface of the substrate is as follows. First, a screen plate is attached to a printing machine, a paste-like object is supplied onto the screen plate, and then the squeegee is pressed onto the screen plate, thereby bringing the screen plate into linear contact with the surface of the printing material. . Then, by proceeding with the squeegee on the screen plate, a paste-like object is discharged onto the surface of the substrate through the pits of the screen plate. Thereby, the bump of a paste-like object can be formed on the substrate surface.

  The plate member used as the screen plate is made of, for example, aluminum, nickel, stainless steel, copper, brass or the like, and the thickness thereof is, for example, about 50 μm to 500 μm (more specifically, for example, 150 μm below). It is. The nominal diameter of each pit is, for example, about 50 μm to 500 μm (more specifically, 150 μm in the following). Here, for example, three times of printing is performed while using a screen plate having such a pit diameter, and a drying process is sandwiched, thereby forming a bump having a height of, for example, about 100 μm.

  Here, for the sake of convenience, it is assumed that this screen version has six regions vertically and six regions horizontally. The number of regions can be considered to be equal to the number of bumps to be formed at the maximum. However, the number is sufficient to identify the algebraic function described later (this order is appropriate from the second or third order, for example, based on experimental experience). In the example described below, it is assumed that there are six regions, and the algebraic function is quadratic.

  FIG. 2 shows the state of the area on the screen plate. FIG. 2 is a configuration diagram showing an arrangement example of each area taken on the screen plate. As shown in FIG. 2, the screen plate 21 has areas arranged next to each other, such as the vertical areas 1, 2,..., 6, and at the same time, the horizontal areas 1, 2,. There is an area of arrangement next to each other. Here, the longitudinal direction of the screen plate 21 coincides with the longitudinal direction of the screen printing squeegee, and the lateral direction coincides with the direction in which the squeegee advances. The size of the vertical area and the horizontal area in the screen plate 21 is, for example, 400 mm in length and 500 mm in width, for example. The number of pits per one area is, for example, thousands. The actual screen plate 21 is provided with a spare area (not shown) for attachment to a printing machine outside the 400 mm × 500 mm area, and has a size of, for example, 550 mm × 850 mm as a whole.

  After bumps are printed and formed on the surface of the substrate, each bump height is measured using a dedicated machine (step 12). By using a dedicated machine, the height of a large number of bumps can be measured efficiently in a short time. The bump height measurement principle of this special-purpose machine is that light is applied from an oblique angle to the surface of the printed material, the shadow caused by the bump is photographed with an image sensor, and the obtained captured image is image-processed. . Such image processing enables high-speed measurement even if the number of bumps is tens of thousands in total. The height of each bump is held in association with its position coordinate on the surface of the printed material (and therefore, it corresponds to which of the vertical region and the horizontal region corresponds).

  Instead of measuring the height of all the printed and formed bumps, for example, the height of some of the bumps sampled at a certain spatial period may be measured. According to this, the measurement can be further speeded up. Depending on the screen version, the formation density of bumps may be high. In such a case, even if sampling is performed, the quality of the obtained bump height information is hardly deteriorated.

  Here, an example of bump height data obtained by printing and forming bumps on the surface of the substrate and obtained by a dedicated machine will be described with reference to FIGS. FIG. 3 is a layout view showing positions of relatively high bumps formed by a certain uncorrected screen plate. FIG. 4 is a layout view showing the positions of the bumps formed by the same uncorrected screen plate as in FIG.

  That is, FIG. 3 is obtained by setting a certain higher threshold value with respect to the average of the obtained bump height data and plotting points where bumps higher than that are located (black triangles). Indicated by dots). FIG. 4 is obtained by setting a certain lower threshold value with respect to the average of the obtained bump height data and plotting a point where a bump having a height lower than that is located (indicated by a black dot). ). From these figures, when this screen plate is used, bumps are formed higher on the left side of the figure in terms of bump height, and the bumps are particularly high in the vertical end region. You can see that The cause of this is as already described.

  In addition, the screen plate given the layout shown in FIG. 3 and FIG. 4 prints 6 sheets in the horizontal direction and 3 sheets in the vertical direction at a time. It consists of three 12 surfaces. Each of the surfaces corresponds to one wiring board as a final product. In other words, this screen plate has a structure having 18 sheets of 6 × 3, one sheet of 4 × 3 12 faces. It should be noted that the number of sheets and the number of surfaces described here may be numbers irrelevant to the number of regions described above.

  Returning to FIG. 1, after measuring each bump height, next, using the held bump height data, the average value of the bump height is calculated for each of the six regions taken vertically, Further, an average value of the bump height is calculated for every six areas taken horizontally (step 13). This calculation can be obtained easily and at high speed if a predetermined calculation software is provided in a device that performs the image processing (for example, a PC provided with the predetermined software). Note that the process is the same when sampling the bump and measuring the height, but in this case, the average value of the bump height in that area can be estimated by calculating the average value. .

Next, using the six average height values of bumps obtained from the above (referred to as ha1, ha2,..., Ha6), a secondary describing the relationship between the vertical position xa and the bump height h. The function: h = f (xa) = k ₃ xa ² + k ₂ xa + k ₁ is identified using the least squares method (step 14). That is, k ₃ , k ₂ , and k ₁ in this equation are initially unknown, and a sum of six residual square values is obtained, and then k ₃ , k ₂ , and k ₁ that obtain this minimum are obtained. In practice, this least square method can be easily executed by using, for example, general spreadsheet software.

The same processing as described above is performed on the side. That is, by using the average value of six bump heights related to the horizontal obtained from the above (referred to as hb1, hb2,..., Hb6), a quadratic function of the horizontal position xb versus the bump height h: h = g (Xb) = k ₃ xb ² + k ₂ xb + k ₁ is identified using the least squares method (step 14). That is, k ₃ , k ₂ , and k ₁ in this equation are initially unknown, and a sum of six residual square values is obtained, and then k ₃ , k ₂ , and k ₁ that obtain this minimum are obtained.

  Then, the quadratic function h = f (xa) relating to the obtained vertical position is normalized using the average value of ha1, ha2,..., Ha6 (step 15; hn = fn (xa)) . That is, both sides of h = f (xa) are divided by this average value. This normalized quadratic function is a function indicating the ratio of the bump height at each vertical position to the global average bump height. Similarly, the quadratic function h = g (xb) relating to the lateral position is also normalized (step 15; hn = g (xb)). This normalized quadratic function is a function indicating the ratio of the bump height at each lateral position to the global bump height average.

  Next, a screen plate pit diameter correction coefficient CF is obtained as an inverse of the obtained normalized quadratic function (step 16; CF (xa) = 1 / fn (xa), CF (xb) = 1 / gn. (Xb)). In other words, in accordance with the change in the bump height h with respect to the horizontal position xa or the vertical direction xb, the bump height h becomes smaller as the bump height h becomes larger, and becomes smaller as the bump height h becomes smaller. The correction coefficient CF is obtained.

  In general, if the pit diameter is large, the amount of paste filled in the pit increases, so the bump height formed is higher. On the other hand, if the pit diameter is small, the amount of paste filled in the pit decreases, the bump height decreases. Will be lower. The correction coefficient CF is used to improve the general bump height non-uniformity due to the principle of the screen printing by reversing this general property. If such reverse use is applied, the calculation of the correction coefficient CF is not limited to the inverse of the normalized quadratic function. For example, CF (xa) = 1− (fn (xa) −1) may be used.

  Next, the obtained correction coefficient CF is adjusted (step 17) to obtain an adjusted correction coefficient CFs. This adjustment is to adjust the effect of the correction, and is roughly a conversion as shown in FIG. FIG. 5 is a graph illustrating adjustment of the correction coefficient.

  That is, if the effect of correction is not adjusted, the correction coefficient CF and the adjusted correction coefficient CFs coincide with each other as in “no adjustment” in FIG. If the effect of the correction is increased, the amount of change in CFs with respect to the change in CF increases as in “strong adjustment” (however, CFs = 1 is set when CF = 1 in order to maintain the meaning of normalization). . Also, if the effect of correction is reduced, the amount of change in CFs with respect to the change in CF decreases as in “weak adjustment” (however, CFs = 1 when CF = 1 to maintain the meaning of normalization) To do).

  In practice, it is useful to calculate the post-adjustment correction coefficient CFs through trial and error through experiments. That is, it is possible to adjust more appropriately by initially performing the following step 18 without adjusting the effect of correction, and manufacturing the screen plate and bump formation based on the step 18 and feeding back the results. Further, the characteristic of the change in CFs with respect to CF does not necessarily have to be a straight line as shown in FIG. It is good also as a characteristic containing a curve suitably.

  After adjusting the correction coefficient, next, the respective diameters that should be calculated for each pit of the uncorrected screen plate are calculated using the calculated correction coefficients CFs (xa) and CFs (xb) (step 18). . That is, for example, using the vertical position xa and the horizontal position xb of each pit, this is obtained by multiplying the uncorrected diameter by 150 μm by CFs (xa) and CFs (xb). Here, for xa and xb, the value of the actual position of each pit may be used. However, in a more simplified method, xa or xb at the center of the vertical region or horizontal region to which the pit belongs may be used. Good.

  In any case, the average diameters of the plurality of pits drilled in the adjacent areas are different between the adjacent areas. In the former case, the diameters of a plurality of pits drilled in one area are distributed over a certain width as numerical values, and the diameters of the pits drilled in an adjacent area are also distributed over a certain width as numerical values. It will be. That is, in the former, the screen plate is more sensitive to uniform the height of the bumps to be formed.

  Here, an example in which bumps are printed and formed on the surface of the printing material using the screen plate manufactured by correcting the pit diameter by the above method will be described with reference to FIGS. The procedure for printing and forming bumps has already been described.) FIG. 6 is a layout diagram showing the position of a relatively high bump among bumps formed by a screen plate with a corrected pit diameter. FIG. 7 is a layout diagram showing the positions of the bumps formed by the same screen plate as in FIG.

  FIGS. 6 and 7 correspond to the layouts shown in FIGS. 3 and 4 which are uncorrected screen plates after correction. That is, FIG. 6 is obtained by setting a certain higher threshold value with respect to the average of the obtained bump height data, and plotting points where bumps higher than that are located (black triangles). Indicated by a dot). FIG. 7 is obtained by setting a certain lower threshold value with respect to the average of the obtained bump height data and plotting a point where a bump having a height lower than that is located (indicated by a black dot). ). The screen plate used here uses the actual vertical position xa and horizontal position xb of each pit for CFs (xa) and CFs (xb) for pit diameter correction, respectively.

  As can be seen by comparing FIG. 6 and FIG. 7 with FIG. 3 and FIG. 4, according to the present method, the global bump height non-uniformity is greatly improved. That is, a screen plate that can make the height of the bumps formed by discharging the paste more uniform within the screen plate is obtained. Here, the corrected pit diameter of the screen plate is 156 μm at the maximum and 146 μm at the minimum. The variation in the height of the formed bump was 0.090 (99% or more of the bumps were included in the height variation of ± 9.0%) when viewed at 3σ / (average h).

  Further, CFs (xa) and CFs (xb) for pit diameter correction are calculated using the vertical position xa and the horizontal position xb at the center of the vertical region or the horizontal region including each pit, respectively. Thus, a screen plate with each pit diameter corrected was manufactured, and the case where bumps were printed and formed in the same manner was examined. The corrected pit diameter of this screen plate is a maximum of 155 μm and a minimum of 146 μm. The variation in the height of the formed bump was 0.092 (99% or more of the bumps were included in the height variation of ± 9.2%) when viewed at 3σ / (average h).

  For comparison, the following results were obtained for a screen plate in which no correction was made for the pit diameter. In this case, the pit diameter of the screen plate is uniformly 150 μm. The variation in the height of the formed bump was 0.109 (99% or more of the bumps were included in the height variation of ± 10.9%) when viewed at 3σ / (average h).

  The uniform formation of bump height by this method is an improvement of global non-uniformity. This point can be understood by comparing FIGS. 3 and 4 with FIGS. The bump height non-uniformity remaining after application of the method is a local non-uniformity at various points in the screen plate. By the way, when the above method is executed to obtain a corrected screen plate in the case where the global bump height variation is shown in FIGS. 3 and 4, the pit diameter is small on the upper side and the pit diameter is on the center in the vertical direction. Large and lower screen version with small pit diameter. In the horizontal direction, the screen version has a smaller pit diameter on the left side and a larger pit diameter toward the right side.

  The description with reference to FIG. 1 is for the case where the distribution of global bump height variation when the uncorrected screen plate is used occurs both in the vertical direction and in the horizontal direction (that is, FIGS. 3 and 4). The case is as follows. If global bump height variation is small enough to be ignored in either direction, no area is divided in that direction, and only one of the other areas is divided. Based on the above, the above method can be executed.

  The example of the screen plate pit diameter correction coefficient acquisition method for obtaining the screen plate according to the embodiment of the present invention has been described above. First, the three-way relationship between the number of bumps in the screen version, the number of areas to be taken, and the order of the algebraic function. The number of bumps is generally a very large number (for example, on the order of tens of thousands), but the number of regions and the order of the algebraic function may be determined regardless of the number.

  Since the order of the algebraic function describes the global tendency of the bump height distribution, it is not necessary to increase it indefinitely. From an experimental point of view, for example, the order of the second or third order is appropriate (however, In principle, it can be a higher order, or at least a first order). The number of areas to be taken is set to the number of areas that can be obtained for the combination of the position and the bump height necessary for identifying the quadratic function and the cubic function. For example, if the algebraic function is quadratic, the number of regions to be taken can be at least 3, and at most the same as the number of bumps (in this case, it is no longer necessary to call it “region”). . The case where the algebraic function is other than the second order, for example, the first order or the third order can be considered similarly.

  As the next supplementary item, in the above description, the bump height was actually measured, but the bump height was estimated without using such a direct method, and the estimated value was used as the bump height. It may be used to perform the above-described series of processing. That is, a model for deriving the bump height to be formed is determined, and the actual screen version is a method for estimating the bump height by using a simulation based on this model. The model includes various factors that determine the bump height (for example, a vector speed at which each part of the screen plate is separated from the printing material) as parameters. The simulation accuracy can be improved by making these various factors known and incorporating them into the model.

  Further, as a supplementary matter, in the above description, for example, a quadratic algebra function is obtained, and then a correction coefficient is obtained, but each average value of bump heights existing in a certain range (for example, a range of 10 mm), respectively. For example, the normalization of the bump height average value may be performed, and the correction coefficient may be derived so that the reciprocal is used as the correction coefficient without identifying the algebraic function. In this case, the function is not a continuous function such as an algebraic function, and for example, a discrete whose value changes every 10 mm can be regarded as a function.

In the description of FIG. 1, the following series of processing is performed by separately obtaining the vertical function h = f (xa) and the horizontal function h = g (xb). It can also be. That is, the bump height h is expressed as a binary function of the vertical position xa and the horizontal position xb, for example, h = m ₆ xa ² + m ₅ xb ² + m ₄ xaxb + m ₃ xa + m ₂ xb + m ₁ Using the least square method using the average bump height in the region, each coefficient of this equation is identified, and a series of processes are performed.

  Further, regarding the drilling for making pits in the screen plate, drilling using a laser beam is suitable for dealing with the difference in diameter. If laser light is used, for example, the hole diameter can be continuously changed by correspondence on software. In the case of drilling by mechanical drilling, it is somewhat difficult to change the hole diameter finely and continuously, but for example, a drill with several diameters is set, and the hole to be actually formed is the most suitable diameter. It is possible to adopt a method such as using a hole with a nearby drill.

  21 ... Screen version.

Claims (12)

A plurality of pits for discharging the paste, and a first region in which an average diameter of the plurality of pits is a first predetermined size;
A second predetermined region that is located next to the first region and has a plurality of pits for discharging paste, and an average diameter of the plurality of pits is different from the first predetermined size; And a second region having a size of 1. A screen plate characterized by comprising:   A region located adjacent to the second region on the side opposite to the first region, wherein a plurality of pits for discharging paste are formed, and an average diameter of the plurality of pits is the second diameter. The screen plate according to claim 1, further comprising a third region having a third predetermined size different from the predetermined size.   The screen plate according to claim 2, wherein the first area, the second area, and the third area are areas adjacent in the vertical direction.   The average diameter of the plurality of pits in the second area is larger than both the average diameter of the plurality of pits in the first area and the average diameter of the plurality of pits in the third area. Item 4. A screen plate according to Item 3.   The screen plate according to claim 1, wherein the first region and the second region are regions adjacent in the horizontal direction.   3. The screen plate according to claim 2, wherein the first region, the second region, and the third region are regions adjacent in the horizontal direction.   The average diameter of the plurality of pits in the first area is smaller than the average diameter of the plurality of pits in the second area, and the average diameter of the plurality of pits in the second area is equal to the plurality of pits in the third area. The screen plate according to claim 6, wherein the screen plate is smaller than the average diameter of the pits. The diameters of the plurality of pits drilled in the first region are numerically distributed in a first predetermined width,
2. The screen plate according to claim 1, wherein the diameters of the plurality of pits drilled in the second region are numerically distributed in a second predetermined width. The diameters of the plurality of pits drilled in the first region are numerically distributed in a first predetermined width,
The diameters of the plurality of pits drilled in the second region are numerically distributed in a second predetermined width,
The screen plate according to claim 2, wherein the diameters of the plurality of pits drilled in the third region are numerically distributed in a third predetermined width. A step of setting n areas (n is an integer of 2 or more) in the horizontal direction or the vertical direction in a screen plate having a large number of pits;
Printing and forming bumps on the surface of the substrate using the screen plate; and
Measuring each of the heights of the bumps formed on the surface of the substrate to be printed or the heights of some sampled bumps of the bumps formed on the surface of the substrate to be printed;
Estimating an average height of the bumps for each of the n regions;
Identifying a function describing a relationship between a horizontal or vertical position x and a bump height h in the screen plate from the average value for each of the n areas using a least square method;
A correction coefficient at an arbitrary horizontal or vertical position x that increases as the bump height h increases and decreases as the bump height h changes in accordance with the change in the bump height h with respect to the horizontal or vertical position x in the function. Obtaining CF (x);
Using the correction coefficient CF (x) to determine the value of the diameter of each pit that should be present for an arbitrary screen plate;
And a step of drilling pits in the plate member based on the value of the desired diameter.   11. The method for producing a screen plate according to claim 10, wherein the function is an algebraic function of an order of 1 to n-1. A step of setting n regions (n is an integer of 2 or more) in the horizontal direction or the vertical direction on a screen plate having a large number of pits, and printing bumps on the surface of the substrate using the screen plate; A step of forming, a step of measuring each of the heights of the bumps formed on the surface of the substrate to be printed or the heights of some of the sampled bumps among the bumps formed on the surface of the substrate to be printed, A step of estimating an average value of the bump height for each of the n areas, and a horizontal or vertical position x and a bump height h of the screen plate from the average value of the n areas. In accordance with the step of identifying the function describing the relationship using the least square method and the change in the bump height h with respect to the horizontal or vertical position x in the function, the smaller the bump height h, the smaller The step of obtaining the correction coefficient CF (x) at an arbitrary horizontal or vertical position x, which is so large, and the pits to be included in an arbitrary screen plate by using the correction coefficient CF (x) The screen plate obtained through the step of obtaining the value of the desired diameter and the step of drilling pits in the plate member based on the value of the desired diameter is attached to the printing press,
Supplying a paste-like object on the screen plate,
By pressing the squeegee on the screen plate, the screen plate is brought into linear contact with the surface of the substrate,
Bumps characterized by causing the paste-like object to be ejected onto the surface of the printing material through pits of the screen plate by advancing the squeegee on the screen plate. Forming method.

Images