JP2007261009A - Squeegee for screen printing and screen printing equipment having it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a squeegee for screen printing which realizes excellent rolling, pressing and scraping properties of a printing material and enables screen printing of high quality being free from rubbing off, omission, etc. of the printing material, and screen printing equipment using it. <P>SOLUTION: The squeegee for screen printing moves on a mask supplied with the printing material and fills the material in an opening part of the mask. The squeegee has a main body part which undergoes a pressing force loaded at the time of printing and a sliding part which is provided at one end of the main body part and slides in relation to the mask. The sliding part has such a flexibility that it is deformable by the pressing force loaded in printing, within a sphere of contact of the printing material with it. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a screen printing squeegee and a screen printing apparatus including the same, and more particularly to a screen printing squeegee suitable for printing paste or flux on a substrate or wafer as an electronic member, and the same. The present invention relates to a screen printing apparatus.

  A screen printing method is known as a method for printing cream solder or conductive paste on a substrate on which electronic components are mounted, or printing flux on a wafer on which solder balls are mounted. In the screen printing method, as shown in FIG. 7A, the paste or flux (hereinafter referred to as flux f) supplied on the mask is moved by moving the squeegee 92 on the mask 111 in the horizontal direction. 113 is filled, and the flux f is transferred to a substrate or wafer (hereinafter collectively referred to as wafer W) set below the mask 111.

  Here, in order to print the flux on the wafer without causing rubbing due to lack of flux, it is necessary to supply the flux sufficiently to the opening, and the flux is sufficiently rotated (rolling) when spreading. ) The squeegee is required to have a property (hereinafter referred to as flux rolling property). Further, after the printing is completed, when the mask is released from the wafer, the flux needs to be sufficiently adhered to the wafer so that the flux is peeled off from the wafer and the printing is not lost. For this reason, the squeegee is required to have a characteristic that the flux supplied to the opening can be pressed in the direction of the wafer with an appropriate pressing force (hereinafter referred to as flux pressing property). The surface of the mask is not flat, and the squeegee needs to have an appropriate flexibility in order to press the flux in close contact with the uneven surface of the mask. Conventionally, a plate-like squeegee made of a rubber material having an appropriate flexibility has been generally used to satisfy the above characteristics.

  The quality of the rolling property depends on various factors such as the moving speed of the squeegee and the surface roughness of the portion in contact with the flux of the squeegee. In particular, the angle formed between the surface of the squeegee and the mask (FIG. 7 ( The so-called contact angle in a) is important. That is, as shown in FIG. 7A, the squeegee 92 moves on the surface of the mask 111 while being pressed with a predetermined pressing force F in a state where it is inclined with respect to the surface of the mask 111 by a predetermined contact angle θ. When the squeegee 92 is made of a plate-like rubber material, the entire squeegee 92 is greatly deformed by the pressing force F, so that the inclination angle θ1 of the portion in contact with the flux f is different from the predetermined contact angle θ. It becomes. As a result, since the rolling property is deteriorated, the supply amount of the flux f to the opening 113 is insufficient, and the printed flux f may be rubbed. Therefore, when the pressing force F is reduced, the pressing force is reduced and the flux f does not adhere to the wafer W. Therefore, when the mask 111 is released, the flux f may be separated from the wafer W and the flux f may be lost.

An example of a squeegee for solving this problem is disclosed in Patent Document 1. The squeegee 82 described in Patent Document 1 has a structure in which a soft first rubber plate 821 and a hard second rubber plate 822 are bonded together with an adhesive, as shown in FIG. 7B. According to the squeegee 82 having this configuration, the strength is reinforced by the hard second rubber plate 822, so that the deformation of the squeegee 82 with respect to the pressing force is reduced and a predetermined contact angle is maintained, so that a change in rolling property is small. Moreover, since the pressability of the flux is ensured by sliding the soft first rubber plate 821 in contact with the mask, there is an advantage that the flux does not easily come off after printing.
JP-A-9-290498 (paragraph 0006)

  On the other hand, the squeegee 82 described in Patent Document 1 has the following problems. The first problem is a rolling property. That is, although the squeegee 82 of Patent Document 1 reinforces the first rubber plate 821 with the second rubber plate 822 with the above configuration, as shown in FIG. 7C, the squeegee 82 is loaded on the squeegee 82 during printing. The contact portion of the first rubber plate 821 that is in contact with the mask due to the pressing force may be greatly deformed. When the contact angle θ1 between the contact portion and the mask 111 is different from the predetermined contact angle θ, the rolling property of the flux f changes, so that the flux f is rubbed. In order to solve this problem, if the hardness of the first rubber plate 821 is increased, the flexibility becomes insufficient, and the pressability of the flux is lost.

  As a second problem, there is a problem of mask deformation due to a squeegee. That is, the first rubber plate 821 is a soft rubber and has a large frictional resistance with the mask 111 when sliding, and the mask 111 is deformed in the plane direction by the frictional force. Further, when the contact portion of the first rubber plate 821 with the mask 111 is in the opening 113 of the mask 111, the contact portion is deformed to enter the opening 113. . The contact portion is caught by the edge of the opening 113 when it comes out of the opening 113, thereby further deforming the mask 111. Such deformation of the mask 111 causes problems such as positional deviation of the pattern of the printed flux f. Such a problem may be solved by selecting a rubber having an appropriate flexibility (hardness), but it requires a lot of trial and error, which is not preferable for industrial production. In recent years, the above-mentioned problems have become apparent due to the finer pitch of wiring patterns accompanying the downsizing of electronic components and the increased size of masks accompanying the increase in size of wafers.

  The present invention has been made in view of the above-mentioned problems of the prior art, and realizes a good rolling property and pressability of the printing material, and enables high-quality screen printing without rubbing or coming off the printing material. The first object is to provide a screen printing squeegee and a screen printing apparatus using the same. Furthermore, the present invention provides a squeegee for screen printing that enables high-quality screen printing with little deformation of the mask in the plane direction during printing and little misalignment of the printed material, and a screen printing apparatus using the same. The second purpose is to provide it.

  One aspect of the present invention that solves the above problem is a screen printing squeegee that moves on a mask supplied with a printing material and fills the opening of the mask with the printing material, and is a pressing force applied during printing. A main body that receives force, and a sliding portion that is provided at one end of the main body and slides on the mask, and the sliding portion is pressed during printing within a range where the printing material contacts A squeegee for screen printing having flexibility that can be deformed by force. In the above, the “printing material” is mainly liquid and includes viscous printing material such as paste or gel. According to the squeegee having such a configuration, the sliding portion provided at one end of the main body has flexibility that can be deformed by a pressing force applied during printing within a range where the printing material contacts. The contact angle in the main body is maintained, and as a result, the rolling property of the printing material does not change. Moreover, since the sliding part has a softness | flexibility, the pressability of a printing material is realizable.

  In the squeegee of the above aspect, in order to maintain the rolling property of the printing material, the main body portion and the mask and the main body when the pressing force per unit length at the squeegee tip loaded during printing is 0.1 N / mm. It is preferable that the contact angle between the first and second portions has rigidity that is 5 ° or less. Such a main body can be suitably realized by setting its mechanical strength to a tensile strength of 15 MPa or more.

  In the squeegee of the above aspect, it is preferable that the sliding portion is a protrusion that is thinner than the thickness of the main body portion. By adopting this configuration, for example, even when the rigidity (hardness) of a material that satisfies the static friction coefficient is high, it is possible to easily realize a sliding portion having appropriate flexibility by appropriately forming the protrusion. Become. Such a sliding part can be suitably realized by satisfying the following formula (1).

[Equation 1]
(S1 / T1) ³ > (S2 / T2) ³ (1)
Where T1: sliding part thickness, S1: sliding part length
T2: thickness of the main body, S2: length of the main body

  In the squeegee of the above aspect, the sliding portion is preferably made of a resin having an A shore hardness of 50 to 95 measured according to JIS K6253. By configuring the sliding portion with a resin having such a hardness, it is possible to realize a sliding portion that can be deformed following the unevenness of the mask by a pressing force during printing. In addition, this sliding part can comprise the whole sliding part, for example with the said resin, or can also comprise only the part which contact | abuts the mask of a sliding part with the said resin. In addition, it is preferable because the sliding portion can be configured relatively easily, and a very thin sliding portion can be configured corresponding to the unevenness level of the mask.

  Furthermore, in the sliding part, in order to reduce the frictional force generated between the sliding part and the mask and eliminate the deformation of the mask in the plane direction, the static friction coefficient of the sliding part is set to 1.2 or less. It is preferable.

  In addition, in order to suitably realize the squeegee, it is desirable that the sliding portion is made of a fluororesin having a small static friction coefficient.

  In addition, in order to realize the squeegee suitably, it is desirable that the main body portion is made of a fluororesin having a relatively large rigidity among the resin materials.

  Another aspect of the present invention that solves the above-described problem is a screen printing apparatus that prints a printing material in a predetermined pattern on one surface of a printing material, and includes an opening corresponding to the pattern, and the printing material includes the opening. A mask having a printing region to be supplied and one surface aligned in a predetermined positional relationship with respect to one surface of the substrate, and the printing region from the other surface side of the mask aligned with the substrate And a screen printing squeegee as described above, which is arranged to supply the printing material to the printing region while pressurizing the printing member and to be movable in at least one direction above the printing member. .

  According to such a screen printing apparatus, the mask is aligned with one surface of the substrate to be printed so that one surface thereof has a predetermined positional relationship. The squeegee supplies the printing material to the printing area from the other side of the mask aligned with the substrate while moving above the printing member from one end to the other end of the printing member. The included opening is filled with printing material. At this time, since the squeegee is configured as described above, the printing material is printed on the printing medium without rubbing and missing.

  As described above, according to the present invention, the sliding portion of the squeegee is configured to have flexibility that can be deformed by the pressure applied during printing within the range where the printing material comes into contact. Screen printing squeegee that can sufficiently realize both rolling and pressing properties and enables high-quality screen printing without rubbing and missing printing material printed on a printing medium, and a screen using the squeegee A printing apparatus can be provided. Furthermore, by setting the static friction coefficient of the sliding portion to 1.2 or less, the frictional force generated between the sliding portion and the mask is reduced and the deformation of the mask in the plane direction is eliminated. Therefore, it is possible to provide a screen printing squeegee that prevents high-quality screen printing and a screen printing apparatus using the squeegee.

  The present invention will be described based on the embodiments with reference to the drawings. Here, FIG. 1 is a perspective view showing a schematic configuration of a screen printing apparatus in which the squeegee of the first aspect according to the present invention is incorporated, and FIG. 2 is a diagram in which a flux as a printing material is printed by the screen printing apparatus of FIG. FIG. 3 is a perspective view of the screen printing apparatus of FIG. 1, and FIG. 4 is an enlarged cross-sectional view of the squeegee of the first mode of FIG. 1 and a state during printing. FIG. 5 is a diagram showing a state during printing of the squeegee of the second and third aspects according to the present invention, and FIG. 6 is a diagram for explaining a printing result when printing is performed with the squeegee of FIG. Hereinafter, although an example of printing a flux on a wafer will be described as an embodiment of the present invention, the present invention is not limited to the embodiment and can be carried out within the same scope as the gist of the present invention.

  In the embodiment of the present invention described below, as shown in FIG. 2, a printing object to be printed is mounted with a solder ball B having a diameter of about 80 to 150 μm on a plate-like electrode p arranged in a predetermined pattern. An example in which paste-like flux is applied to the flat electrode p before the solder ball B is mounted on the wafer W to be mounted will be described. Note that there are two known screen printing methods, an off-contact method and a contact method, classified according to whether or not the mask is brought into close contact with the wafer W, and the present invention can be applied to either method. An example of use in an off-contact screen printing apparatus that is said to be difficult to achieve printing accuracy will be described.

[First Embodiment]
Hereinafter, the screen printing squeegee of the first aspect and the screen printing apparatus using the squeegee will be described.

* Mask In the screen printing apparatus 1 of the first aspect, reference numeral 111 denotes a flat metal mask. The mask 111 is stretched around the frame-shaped support portion 112 from the periphery by a member having elasticity or elasticity. In the mask 111, a plurality of openings 113 corresponding to the arrangement pattern of the flat electrodes p of the wafer W are formed. The mask 111 is aligned with a predetermined positional relationship with respect to the printing region 114 including a plurality of openings 113 filled with the flux f and the upper surface (one surface) of the wafer W on which the plate-like electrodes p are arranged. And a back surface (one surface). Here, the mask 111 can be made of nickel, stainless steel, or the like, and the thickness of the mask 111 can be appropriately set in consideration of the size of the solder ball, the size of the flat electrode p, and the like, for example, about φ100 μm. The thickness when the solder ball is intended is about 50 μm. The opening 113 can be formed by a known processing method such as laser processing, etching processing, or precision electrocasting. In addition to the metal, the mask 111 may be made of resin, ceramics, a composite material of resin and metal, or the like.

  Here, since the screen printing apparatus 1 employs an off-contact method, the back surface of the mask 111 of the first aspect has a predetermined gap, that is, a snap-off G with respect to the upper surface of the wafer W as shown in FIG. Aligned to have. Note that reference numeral 14 in FIG. 1 denotes a flat table on which the wafer W is placed. It is preferable to incorporate a vacuum suction means or the like for vacuum-sucking the wafer W into the table 14 because the mounted wafer W is attracted and fixed to the table 14.

* Squeegee unit Reference numeral 12 denotes a squeegee unit that operates the squeegee 121 of the first aspect. The squeegee 121 has a flat plate shape with a substantially rectangular cross section, and the length in the longitudinal direction (Y direction) has a size including the printing region 114. The squeegee unit 12 includes a horizontal moving means 122 that can move horizontally from one end to the other end (X direction) of the mask 111, and a squeegee 121 that is incorporated in the horizontal moving means 122 onto the lower mask 111 with a predetermined pressing force F. A pressing means 123 for pressing is provided. The pressing means 123 is composed of a cylinder or the like, for example, and a squeegee 121 is attached to the lower end of the rod. Here, as shown in FIG. 3, the squeegee 121 is positioned such that the contact angle θ between the surface of the mask 111 and the squeegee 121 forms a predetermined angle with respect to the traveling direction C during printing. For example, for the purpose of cleaning the flux f remaining on the surface of the mask 121 when the squeegee 121 moves backward, contact angle changing means (not shown) for changing the inclination angle θ of the squeegee 121 when moving backward is provided. May be.

  According to the squeegee unit 12 having the above-described configuration, the squeegee 121 is pressed against the mask 111 at the lower end corner portion on the traveling direction C side by the pressing means 123, while the mask 111 is brought into close contact with the wafer W by the horizontal moving means 122. Slide on the mask 111. The opening 113 is filled with the flux f while spreading the flux f supplied to the upper surface of the mask 111 and passing through the printing region 114. Here, the mask 111 in which the opening 113 is filled with the flux f is released from the wafer W in order to restore the original state of the snap-off G by the tension after the squeegee 121 passes. Accordingly, the flux f is transferred to the wafer W corresponding to the pattern of the opening 113.

* Squeegee Hereinafter, the configuration of the squeegee 121 will be described in more detail with reference to FIG. The squeegee 121 receives a pressing force F of the pressing means 123 and has a main body portion 1211 having a predetermined rigidity capable of restricting deformation by the pressing force F, and a lower end (one end) of the main body portion 1211. A sliding portion 1212 that slides while copying is provided.

  Here, the squeegee 121 of this embodiment is an integral product made of tetrafluoroethylene resin, which is a fluororesin, and the main body portion 1211 and the sliding portion 1212 are both made of tetrafluoroethylene resin. Note that the squeegee 121 may be configured by combining the separate main body portion 1211 and the sliding portion 1212. For example, the main body portion 1211 may be made of a material having relatively high rigidity such as a metal, and the sliding portion 1212 formed of resin or the like may be attached to the main body portion 1211 by bonding or the like. However, since the main body portion 1211 and the sliding portion 1212 are integrated as in this aspect, the squeegee 121 can be used simply without considering the peeling of the sliding portion 1212 and the like, which is preferable for industrial production.

* Main part of squeegee Tetrafluoroethylene resin constituting the main body part 1211 has a tensile strength of about 15 to 35 MPa and a hardness of about 50 to 60, which is moderate in plastic and soft in hardness. Although it is a so-called semi-rigid plastic, it is difficult to bend as compared with the case where the tensile strength of general rubber is 1 to 10 MPa. Therefore, the main body portion 1211 has much higher bending rigidity than the rubber plate having the same width, thickness, and length, and can substantially maintain the inclination angle θ.

  The main body portion 1211 is a tetrafluoroethylene resin which is a fluororesin, but Test 1 and Test 2 were performed and confirmed for other configurations.

(Test 1)
In FIG. 4A, S1 = 2mm, T1 = 0.56mm, S2 = 20mm, length 210mm, and flux f (made by Senju Metal: Delta Lux 523H) is printed with the squeegee 121 having a different thickness T2 of the main body 1211. Then, the change in the contact angle θ due to the pressing force F between the main body portion 1211 and the mask 111 at that time was measured, and the state of occurrence of rubbing of the flux f after printing was confirmed (Examples 1 to 3, Comparative Example 1). 2). The results are shown in Table 1. Test 1 is for a squeegee 121 in which a Φ80 μm size electrode pad formed on a Φ200 mm wafer is set to 2 million fluxes Φ80 μm at a pitch of 150 μm and a contact angle θ is set to 60 °. Printing was performed while pressing with a pressing force of 21 N, that is, with a pressing force of 0.1 N / mm per unit length of the squeegee 121. The contact angle θ of the squeegee 121 is preferably set in the range of 30 ° to 80 °. This is because the pressing property of the flux f is impaired even when the contact angle θ is too small or too large.

  Here, since the sliding portion 1212 and the mask 111 are in a substantially line contact state, the evaluation of the pressing force F is a pressing force per unit length of the squeegee 121. The printing mask 111 was a Ni-plated metal mask having a thickness of 40 μm. Furthermore, the measurement of the contact angle θ by the pressing force F was performed by measuring the squeegee 121 during printing with a camera from the side and analyzing the obtained image. The change in the inclination angle θ is the difference between the contact angle θ set by the main body 1211 and the mask 111 and the minimum angle during printing. Further, the state of occurrence of rubbing of the flux f was visually confirmed, and the quality was judged by the presence or absence of rubbing.

(Test 2)
In FIG. 4 (a), S1 = 2mm, T1 = 0.56mm, S2 = 20mm, T2 = 12mm, length 210mm, the material of the main body 1211 is changed, and the squeegee 121 having different tensile strength is used. When the printing was performed under the same conditions, the change in the contact angle θ between the main body portion 1211 and the mask 111 due to the pressing force F was measured, and the state of occurrence of rubbing of the flux f after printing was confirmed (Examples 4 to 6). Comparative Examples 3 and 4). The results are shown in Table 2.

  As described above, the main body portion 1211 is not limited to the fluororesin, and may be configured to have rigidity that prevents the main body portion 1211 from being greatly deformed by the pressing force F acting on the squeegee 121. It can be seen from the results of Test 1 that the change in the contact angle θ between the main body portion 1211 and the mask 111 due to the pressing force F preferably has a rigidity of 5 ° or less. Moreover, it turns out from the result of the test 2 that the main-body part 1211 which has such rigidity is implement | achieved by comprising from the material of 15 MPa or more of tensile strength.

* Sliding part of squeegee The sliding part 1212 of this aspect is a pair of lip shapes provided on both sides along the longitudinal direction (Y direction) on the surface of the squeegee 121 facing the mask 111, that is, one end of the main body part 1211. It is a projection body. Such a protrusion is formed by processing a groove in the center of one end of the squeegee 12. By providing two protrusions in this way, the sliding portion 1212 can be operated in any direction of reciprocation of the squeegee 121. Further, as shown in FIG. 4B, the sliding portion 1212 is formed to have a length S1 that can be deformed by the pressing force F within a range where the flux f contacts the squeegee 121.

  Here, during printing, the squeegee 121 slides while the tip corner portion of the sliding portion 1212 is pressed against the mask 111, but the sliding portion 1212 moves relative to the main body portion 1211 so as to closely follow the mask 111. The bending rigidity is 1 / n (n> 1). That is, when the pressing force F acts, the bending of the sliding portion 1212 as a cantilever is made n times larger than the main body portion 1211. As shown in FIG. 4A, the thickness and length of the main body portion 1211 are T2 and S2, the thickness and length of the sliding portion 1212 are T1 and S1, and the main body portion 1211 is the left end in the figure. If the cantilever with the fixed portion as a fixed end and the sliding portion 1212 as a cantilever with the fixed portion as the coupling portion with the main body portion 1211 are defined by the relationship of the following formula (2).

[Equation 2]
(S1 / T1) ³ = n (S2 / T2) ³ (2)

(Test 3)
Here, in the squeegee 121 of Example 6 in the test 2, the test 3 similar to the test 2 is performed with the squeegee 121 having the sliding portion 1212 having a different width T1, and the occurrence state of the flux f missing after printing is confirmed. (Examples 7 to 11 and Comparative Examples 5 and 6). The results are shown in Table 3. In the column of “occurrence of missing” in Table 3, “×” indicates that the occurrence rate of missing is 100 ppb or more, “Δ” is less than 100 ppb and 10 ppb or more, and “◯” is less than 10 ppb (hereinafter referred to as “open”). The same in Test 4).

  If the value of n in the above formula 2 is large, it means that the sliding portion 1212 is more flexible than the main body portion 1211. When n is too small, the flexibility of the sliding portion 1212 is poor, and the sliding portion 1212 cannot be brought into close contact with the surface of the uneven mask 111, so that the flux f is likely to come off. Therefore, the lower limit value of n is 1. In addition, when n is excessively large, the sliding portion 1212 is too flexible, so that when the flux f is pressed, the sliding portion 1212 is easily deformed and the flux f cannot be sufficiently pressed. The flux f is lost. Therefore, the upper limit value of n is 50. It should be noted that 5 ≦ n ≦ 20 is preferable in order to reduce the occurrence rate of flux f to 10 ppb or less.

  Although the sliding portion 1212 is made of the same tetrafluoroethylene resin as the main body portion 1211, the sliding portion 1212 is formed in a lip shape as described above, and thus has an appropriate flexibility as compared with the main body portion 1211. Therefore, the sliding portion 1212 elastically abuts on the surface of the mask 111 by the pressing force F, so that the followability and followability to the surface of the mask 111 are improved. Further, the sliding portion 1212 made of tetrafluoroethylene resin has an appropriate hardness and has a very small coefficient of friction, so that it does not get caught on the edge of the opening 113, and in the plane direction when sliding on the surface of the mask 111. The mask 111 is not deformed.

  Although the sliding part 1212 is a tetrafluoroethylene resin which is a fluororesin, Test 4 was performed and confirmed for other configurations.

(Test 4)
An ethylene tetrafluoride resin material constituting the squeegee 121 and a resin such as urethane conventionally used as a squeegee material and a surface of a Ni-plated metal mask (thickness: 40 μm, surface roughness: Ra 0.13 μm) Coefficient of static friction and JIS
The hardness of A shore was measured by K6253. A squeegee is formed from these materials, and a flux is printed using the Ni-plated metal mask under the same conditions as in Test 2 above, and a predetermined flux f is printed at the center of the mask 111. The printing deviation amount δ (illustrated) from the position was measured, and the quality of the printed state of the missing flux was visually confirmed (Examples 12 to 15 and Comparative Example 7). Table 3 shows the static friction coefficient, the printing deviation amount δ, the hardness of the resin, and the state of the flux f missing.

  According to the result of the test 4, it can be understood that the flux f is not easily lost by printing with the sliding portion 1212 made of a resin having a predetermined range of hardness. This is because the sliding portion 1212 needs to be close to the surface of the uneven mask 111 and be flexible enough to press the flux f without being easily deformed when pressing the flux f. is there. Therefore, when importance is attached to the absence of the flux f, it is preferable to use a resin having a hardness of 50 to 95 constituting the sliding portion 1212.

  In addition, it can be seen that printing deviation amount, that is, deformation of the mask 111 in the planar direction is suppressed by printing with the sliding portion 1212 made of a resin having a predetermined static friction coefficient. Here, in consideration of the diameter clearance between the printed flux f and the electrode pad, the printing deviation amount δ needs to be 20 μm or less. When the printing deviation amount is 20 μm or less, it is preferable to use a resin having a static friction coefficient of 1.2 or less of the resin constituting the sliding portion 1212.

  As described above, according to the squeegee 121 of the first aspect, the squeegee 121 is pressed against the mask 111 with a predetermined pressing force F, but the inclination angle θ of the main body 1211 having high rigidity is set to a predetermined angle. Since it is maintained, the flux f can be rolled well on the side face facing the traveling direction C. On the other hand, since the sliding portion 1212 is bent by the pressing force F, the inclination angle θ1 of the sliding portion 1212 is smaller than the inclination angle θ of the main body portion 1211, but the length s of the sliding portion 1212 is set to the contact area of the flux f. By making it inside, the rolling property of the flux f is not affected. Therefore, it is possible to satisfactorily fill the opening 113 with the flux f and perform printing without rubbing.

  Further, since the sliding portion 1212 has appropriate flexibility, it deforms following the surface of the mask 111 having irregularities while being bent by the pressing force F. Therefore, the flux f filled in the opening 113 can be pressed, so that the flux f is not lost. It is desirable to configure the pressing means 123 so as to be able to cope with an excessive height variation of the mask 111 that cannot be handled by the sliding portion 1212.

  In addition, since the sliding portion 1212 is made of a fluororesin having a low static friction coefficient and appropriate hardness, the sliding portion 1212 is not caught on the edge of the opening 113, and the sliding portion 1212, the mask 111, The frictional force generated between them can be kept very small. Accordingly, since the deformation of the mask 111 in the plane direction due to sliding with the sliding portion 1212 is extremely small, it is possible to perform printing with a small printing amount and a high printing accuracy.

  As a secondary effect when a fluororesin is used as the material of the squeegee 121, the flux f hardly adheres to the surface of the squeegee 121. Therefore, the flux f adheres to the surface of the squeegee 121 during printing. It has been confirmed that the phenomenon that the rising phenomenon is difficult to occur and the occurrence of defective filling of the flux f can be further reduced. Further, since the sliding portion 1212 made of a fluororesin having a small static friction coefficient is hard to be worn, foreign matter is not mixed in the flux f, and the effect that the life of the squeegee 121 can be extended is also confirmed.

[Second Embodiment]
The second aspect of the present invention will be described with reference to FIG. Note that the configuration of the screen printing apparatus, the substrate, the mask, and the like is the same as that of the first embodiment, and thus description thereof is omitted.

  The screen printing apparatus of the second aspect is basically the same as that of the first aspect described in FIG. 1, and only a part of the squeegee is different. That is, the squeegee 221 of this aspect also has a structure in which the main body portion 2211 and the sliding portion 2212 are formed as an integral member, but the sliding portion 2212 is formed only on one surface corresponding to the traveling direction C during printing. Yes. Therefore, a screen printing apparatus incorporating the squeegee 221 of this aspect can perform a printing operation only when moving in one direction. For example, the squeegee 221 may be applied to a screen printing apparatus in which a forward-only squeegee 221 and a backward-only squeegee 221 are arranged so as to face each other and press the corresponding squeegee 221 against the mask 111 for printing. it can.

[Third embodiment]
A third aspect of the present invention will be described with reference to FIG. Note that the configuration of the screen printing apparatus, the substrate, the mask, and the like is the same as that of the first embodiment, and thus description thereof is omitted.

  The screen printing apparatus according to the third aspect is basically the same as that according to the first aspect described with reference to FIG. 1, and the configuration of the squeegee is different. The squeegee 321 has a structure composed of a separate main body 3211 and a film-like sliding portion 3212 having a thickness s thinner than the contact range of the flux f. The sliding portion 3212 is in contact with the flux f. Within such a range, it has flexibility that can be deformed by a pressing force applied during printing.

  The main body 3211 is a flat plate having a rectangular cross section, and has a predetermined rigidity with respect to the pressing force F during printing. Here, as the material constituting the main body portion 3211, it is preferable to use a material having a predetermined tensile strength similar to that used for the main body portions 1211, 2112 of the first and second embodiments. Resins equivalent to fluororesins, hard plastics, metals, ceramics, etc. can be used. Further, the length and thickness may be appropriately determined so as to correspond to the mechanical characteristics of the material used and the size of the mask.

  The sliding portion 3212 is bonded to a part of the surface (side surface) corresponding to the traveling direction C during printing in the main body portion 3211 and the surface (lower surface) facing the mask 111 and is pressed against the mask 111 by the pressing force F. It is formed of a thin film made of a resin having a flexibility and a coefficient of static friction that can be deformed by about several tens to several tens of μm and can absorb irregularities when sliding with the mask 111. If the sliding part 3212 is made of an adhesive film having a thickness s of several tens to several tens of micrometers, it is only necessary to attach the adhesive film to the main body part 3211 and the squeegee 321 can be constructed very easily. Above preferred.

  According to the squeegee 321 of the third aspect, the squeegee 321 is pressed against the mask 111 with a predetermined pressing force F, but the inclination angle θ of the rigid main body 3211 is maintained at a predetermined angle. The flux f can be satisfactorily rolled on the side surface facing the traveling direction C. On the other hand, although the sliding portion 3212 having appropriate flexibility is bent by the pressing force F, the rolling property of the flux f may be affected by setting the thickness s of the sliding portion 3212 within the contact region of the flux f. Absent. Therefore, it is possible to satisfactorily fill the opening 113 with the flux f and perform printing without rubbing.

  Further, the sliding portion 3212 having moderate flexibility deforms following the surface of the mask 111 having irregularities while being bent by the pressing force F. Therefore, the flux f filled in the opening 113 can be pressed, so that the flux f is not lost.

  Furthermore, if the sliding portion 3212 is made of a fluororesin having a low static friction coefficient, the sliding portion 3212 is not caught by the edge of the opening 113 and is generated between the sliding portion 3212 and the mask 111. The frictional force can be kept very small. Therefore, the deformation of the mask 111 in the plane direction due to the sliding with the sliding portion 3212 is extremely small, so that printing with a high printing accuracy with a small amount of positional deviation of the mask 111 can be performed.

1 is a perspective view showing a schematic configuration of a screen printing apparatus according to the present invention. It is a figure which shows the board | substrate for solder ball mounting as an example of the to-be-printed body which concerns on this invention. It is a figure which shows the AA cross section of FIG. It is a figure which shows the squeegee of FIG. It is a figure which shows the squeegee of another embodiment which concerns on this invention. It is a figure which shows the printing shift | offset | difference when printing using various squeegee materials. It is a figure which shows the structure of the conventional squeegee.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Screen printing apparatus 111 Mask 113 Opening part 114 Print area 12 Squeegee unit 121 (221,321) Squeegee 1211 (2211,3211) Main-body part 1212 (2212,3212) Sliding part 122 Horizontal moving means 123 Pressing means 82 (92) Conventional squeegee f Flux W Wafer θ Squeegee tilt angle F Pressing force

Claims (11)

A squeegee for screen printing that moves on a mask supplied with a printing material and fills the opening of the mask with the printing material,
A main body that receives a pressing force applied during printing, and a sliding portion that is provided at one end of the main body and slides on the mask;
The sliding portion is a squeegee for screen printing having a flexibility that can be deformed by a pressing force applied during printing within a range where the printing material contacts.   The main body has a rigidity such that a change in a contact angle between the mask and the main body is 5 ° or less when a pressing force per unit length at a squeegee tip loaded during printing is 0.1 N / mm. The squeegee for screen printing according to claim 1.   The squeegee for screen printing according to claim 2, wherein the main body has a tensile strength of 15 MPa or more.   The squeegee for screen printing according to claim 1, wherein the sliding portion is a protrusion that is thinner than a thickness of the main body portion. The squeegee for screen printing according to claim 4, wherein the sliding portion satisfies the following formula 1.
(S1 / T1) ³ > (S2 / T2) ³ (1)
Where T1: sliding part thickness, S1: sliding part length
T2: thickness of the main body, S2: length of the main body The sliding part is JIS
The squeegee for screen printing according to claim 1, comprising a resin having a hardness of A shore measured by K6253 of 50 to 95.   The squeegee for screen printing according to claim 6, wherein the sliding portion is made of a resin film.   The squeegee for screen printing according to any one of claims 1 to 7, wherein a static friction coefficient of at least a portion of the sliding portion in contact with the mask is 1.2 or less.   The squeegee for screen printing according to any one of claims 1 to 8, wherein the sliding portion is made of a fluororesin.   The squeegee for screen printing according to any one of claims 1 to 9, wherein the main body is made of a fluororesin.   In a screen printing apparatus that prints a printing material in a predetermined pattern on one surface of a printing medium, an opening corresponding to the pattern, a printing area including the opening and supplied with the printing material, and one surface of the printing medium A mask having one surface aligned with a predetermined positional relationship, and supplying the printing material to the printing region while pressing the printing region from the other surface side of the mask aligned with the substrate. And a squeegee for screen printing according to claim 1, wherein the screen printing squeegee is disposed so as to be movable in at least one direction above the printing member.

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