JP2018118480A - Combination screen plate for contact printing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To acquire a highly durable combination screen plate which is suited for contact printing and capable of highly precise printing.SOLUTION: Provided is a combination screen plate 1 for contact printing, which includes: a frame 2; a printing screen 3; and a support 4 whose inner peripheral part is bonded with an outer peripheral part of the printing screen and whose outer peripheral part is fixed to the frame. The printing screen 3 is a metallic screen. The support 4 is formed with a high-strength metal plate whose elongation rate in a plane direction in squeegeeing is smaller and whose displacement amount in a thickness direction is smaller compared to those of the printing screen. Thus, elongation of the printing screen 3 in the plane direction at the time of contact printing can be suppressed, and the highly precise and highly durable combination screen plate 1 can be acquired.SELECTED DRAWING: Figure 1

Description

The present invention relates to a combination screen plate used for contact-type screen printing.

In screen printing, screens are becoming finer to support fine line printing, and in order to use low-strength and expensive screens, a combination structure is used compared to a direct attachment structure in which a printing screen is directly attached to a frame. The screen version of is becoming mainstream. The combination screen plate is one in which the periphery of a printing screen is fixed to a frame via a support.

In the case of a combination screen plate, a synthetic fiber screen that is more elastic than the printing screen is generally used as the support in order to absorb the load on the printing screen due to the printing pressure during printing by the support (for example, Patent Documents). 1).

However, with recent miniaturization and multifunctionalization of electronic components, the line width of circuits has become finer, and there is an increasing demand for screen printing with higher print coordinate accuracy. For example, in a multilayer product such as a multilayer ceramic capacitor, a printing accuracy of ± 20 μm or less is required. For this reason, the combination screen plate using a support made of a conventional synthetic fiber screen has a problem that the target printing accuracy cannot be achieved.

Patent Document 2 uses a rigidized screen in which a braided surface of a screen mesh formed by braiding stainless steel fibers is used as a printing screen, and is coarser than the printing screen and has a wire diameter as a support screen. A combination screen plate using a rigidized screen in which a plating film is coated on the surface of a braided portion of a screen mesh braided with a thick stainless steel fiber is disclosed. In this case, since the support screen has a smaller elongation than the synthetic fiber screen, the printing accuracy can be improved.

However, since a stainless steel mesh is used as the support, the restored position coordinates after being deformed by the printing pressure of the squeegee are not so good, and the printed figure tends to be distorted. As a result, it is difficult to obtain desired printing accuracy. Furthermore, since the support has a mesh structure similar to the printing screen and needs to be plated, it is expensive. In addition, some of the paste (printing ink) can enter the joints of the support screen, which can adversely affect print quality.

Japanese Patent No. 5529395 JP 2007-62225 A JP-A-8-112891 JP-A-5-254087

An object of the present invention is to provide a combination screen plate that is suitable for contact printing and capable of high-precision printing and has high durability.

Before describing the significance of the present invention, contact printing will be described first. Screen printing is roughly classified into an off-contact method and a contact method. In the off-contact method, a printing material is placed on a horizontally supported printing stage, and a screen printing screen is held with a gap between the printing material and the surface of the printing material. The paste is supplied to the top and horizontally moved while pressing the squeegee against the printing screen, so that the printing screen is bent and the pattern formed on the printing screen is transferred to the printing material.

However, in the printing method using the off-contact method, the printing screen is stretched downward every time squeezing is performed, and at the same time, the printing screen is also stretched in the plane direction by the frictional resistance with the squeegee. As a result, there is a problem that the printing deviation of the pattern formed on the surface of the substrate is likely to increase, and the durability of the printing screen is likely to deteriorate.

On the other hand, in the contact method, the surface of the printing material and the printing screen are held in a substantially contacted state (however, the distance between the printing screen and the printing material is not necessarily zero), and the squeegee is moved horizontally. Thus, the pattern formed on the printing screen can be transferred to the printing material with almost no bending of the printing screen in the thickness direction. Such a contact-type printing method has an advantage that printing displacement and shape deterioration are reduced because the printing screen is less stretched in the thickness direction than the off-contact method.

As described in Patent Documents 3 and 4, a printing stage having an outer peripheral surface with an arc-shaped cross section is used, and the surface of the printing material adsorbed on the outer peripheral surface corresponds to the tip position of the squeegee on the back surface of the printing screen. A contact-type printing method has been developed in which the printing stage is rotated in synchronization with the movement of the squeegee while contacting the position. When a printing stage with such an arcuate outer peripheral surface is used, the printing screen and the stage are partially in contact with the movement of the squeegee, so the printing screen is printed compared to a flat printing stage. There is an advantage that the elongation of the printing screen when peeling from the stage can be suppressed, and the printing accuracy and the durability of the printing screen are improved.

However, even in a contact-type printing method using a printing stage having an arcuate outer peripheral surface, the elongation in the plane direction of the printing screen due to frictional resistance with the squeegee cannot be suppressed.

Therefore, the combination screen plate of the present invention uses a metal screen as a printing screen, uses a metal plate that is stronger than the printing screen as a support, and holds the periphery of the printing screen with this metal plate. It is characterized by. Due to the reinforcing effect of the support, it is possible to suppress the elongation in the plane direction of the printing screen due to friction with the squeegee, the position coordinate reproducibility is better than the conventional combination screen plate, and high-precision printing is possible. Since the support is a metal plate, it can hardly be deformed in the thickness direction, but for contact printing, the support need not be deformed in the thickness direction. Although the screen may extend in the thickness direction when the screen and the stage are peeled off, since the periphery of the screen is supported by a high-strength metal plate, the elongation in the thickness direction of the printing screen can be suppressed. As a result, it is possible to provide a combination screen plate capable of high-precision printing and having high durability.

As the printing screen, a metal screen is used. For example, a known screen such as a SUS screen or a tungsten screen can be used. The printing screen is not limited to a woven structure (mesh) made of metal fibers, and may be a metal mask. In particular, a high-precision screen called a high mesh, in which metal wires are finely knitted finely, is preferable.

A “metal plate” as a support is not a mesh-like or fibrous structure such as a metal mask or mesh, but a flat plate. Although the thickness is not necessarily constant, a flat plate having a constant thickness has a constant strength, is easy to process, and is inexpensive. The metal material for the support preferably has a Young's modulus of 70 GPa or more and 640 GPa or less, and more preferably a Young's modulus of 150 GPa or more and 430 GPa or less. When the printing screen is fixed to the lower surface side of the support, the thickness of the support is preferably 3 mm or less, particularly 1 mm or less in order to reduce the space at the level difference between the support and the printing screen. The thickness is preferably 0.1 mm or more so that deformation due to friction with the squeegee can be suppressed. By using such a thin and high strength support to support a metal printing screen, a screen printing plate having excellent printing workability and high printing accuracy (for example, ± 20 μm or less) can be realized. Even if a low-strength screen such as a high mesh is used as the printing screen, the coordinate reproducibility of the printed figure is high.

The thermal expansion coefficient of the support is preferably 1 × 10 ⁻⁶ / ° C. or more and 23 × 10 ⁻⁶ / ° C. or less, more preferably 4 × 10 ⁻⁶ / ° C. or more and 11 × 10 ⁻⁶ / ° C. or less. Since the thermal expansion coefficient is small, variations in printing accuracy due to temperature changes can be suppressed. Since both the printing screen and the support are made of metal, they are not easily affected by changes in humidity, swelling by chemicals contained in the paste, or chemical changes. Therefore, it is excellent in durability compared with a printing screen and a support made of a synthetic fiber screen. As such a high strength / low thermal expansion / non-moisture absorbing single plate, for example, a stainless steel plate, an aluminum plate, a super invar, a cemented carbide, a copper plate, a high strength steel plate and the like can be generally used.

Since the support is not a screen but a metal flat plate, it is inexpensive. If the support is deformed by multiple uses, it is possible to replace only the support if necessary. Furthermore, since the support is not a mesh structure but a metal flat plate, part of the paste does not enter the joints of the support as in Patent Document 2.

The printing screen is bonded to the support with a predetermined tension, and the support is preferably a metal plate having a thickness that can maintain an undeformed state against the tension of the printing screen. Although there are materials having various Young's moduli in the metal plate, even if the Young's modulus is high, if the plate material is extremely thin, bending may not be suppressed. Therefore, it is preferable to use a metal plate having a thickness that can maintain an undeformed state (flat plate state) against the tension of the printing screen as the support.

The printing screen is preferably joined to the printing stage side of the support. In screen printing, the back side of the combination screen plate comes into contact with the stage (or the substrate to be printed). When the printing screen is bonded to the upper surface side of the support, the back side of the rigid support may interfere with the stage and damage the stage. Further, the printing screen may be stretched by the thickness of the support, and coordinate distortion may occur. Therefore, since the printing screen is bonded to the back side of the support, that is, the printing stage side, interference between the support and the stage can be prevented, and elongation of the printing screen due to the thickness of the support can be suppressed.

The contact printing combination screen plate according to the present invention is preferably applied to a printing apparatus using a printing stage having an arcuate outer peripheral surface as in Patent Document 3. In this case, since it is a contact system, the displacement of the printing screen in the thickness direction can be suppressed, and the printing screen is hardly displaced in the plane direction due to the reinforcing effect of the support, so that high printing accuracy can be achieved. Further, since the printing screen and the stage partially contact with the movement of the squeegee, it is possible to suppress the elongation of the printing screen when the printing screen is peeled off from the printing stage. Durability is further improved.

As described above, according to the present invention, a metal screen is used as a printing screen, a metal plate having a strength higher than that of the printing screen is used as a support, and the periphery of the printing screen is held by this metal plate. Therefore, the reinforcement effect of the support can suppress the elongation in the plane direction of the printing screen due to the friction with the squeegee, the position coordinate reproducibility is better than the conventional combination screen plate, and high-precision printing is possible. . Further, since the metal plate is less deteriorated after many uses than the screen, a combination screen plate having excellent durability can be realized. In the case of a support made of a metal plate, there is no elongation of the support in off-contact printing, and the printing screen cannot contact the substrate, so that paste transfer cannot be performed and printing cannot be performed well. High-definition printing is possible.

It is the top view and AA sectional view taken on the line which show 1st Embodiment of the combination screen plate for contact printing which concerns on this invention. This is an SS curve of a SUS430 plate, a stainless screen, and a polyester screen. It is the figure which compared the coordinate restoration property before and behind printing of the prior art example which uses the polyester screen as a support body, and this invention using a SUS430 board. It is the figure which compared the temperature / humidity change of the prior art example which uses the polyester screen as a support body, and this invention using a SUS430 board. It is sectional drawing of the contact-type printing apparatus to which the combination screen plate shown in FIG. 1 is applied. It is a figure which shows the printing precision of the combination screen plate which concerns on this invention.

FIG. 1 shows a first embodiment of a contact printing combination screen plate according to the present invention. The combination screen plate 1 includes a frame 2, a printing screen 3, and a support 4 whose inner peripheral portion is joined to the outer peripheral portion of the printing screen 3 and whose outer peripheral portion is fixed to the frame 2.

The frame 2 is formed in a rectangular frame shape by a thick member, and is formed in such a size that the squeegee can move inside. The material of the frame 2 is formed of a metal material such as aluminum or aluminum alloy, for example. In the conventional screen printing plate, the frame 2 has a role of holding the tension of the printing screen 3. In this embodiment, the support 4 holds the tension of the printing screen 3. Therefore, the support 4 has a role of firmly supporting the printing screen 3 on the frame 2.

As the printing screen 3, a metal mesh or a metal mask is used. The metal mesh is a braid of fine metal fibers, and for example, a SUS mesh, a tungsten mesh, a high-strength steel mesh, or the like is used. For example, a pattern obtained by patterning a printed figure (not shown) with a photosensitive resin is used on the metal mesh. As the metal mesh, a high-precision screen called a high mesh, in which metal wires are finely knitted finely is preferable. The metal mask is a porous metal mask in which a printing pattern is formed on a metal foil or a metal plate by, for example, etching, laser processing, electroforming, or the like.

The support 4 is made of a single metal plate having a strength higher than that of the printing screen 3, and the outer peripheral portion thereof is fixed to the lower surface of the frame 2 by bonding or the like. A rectangular opening 4a is formed at the center of the support 4 and the outer periphery of the printing screen 3 is fixed around the opening 4a with a predetermined tension. In particular, the printing screen 3 is preferably fixed to the lower surface side of the support 4, that is, the stage side. The reason is to prevent the printed material on the stage from being damaged due to interference with the support plate 4 when the screen plate comes into contact with the printing stage. The fixing method between the support 4 and the frame 2 and the fixing method between the support 4 and the printing screen 3 can be a bonding method other than adhesion.

The size of the support 4 desirably satisfies the following conditions. That is, in order to print without variation, a squeegee's running distance is necessary, and the width W1 of the support 4 in the squeegee movement direction is preferably a dimension that can secure a distance until the paste rolling is stabilized. In addition, if the paste pool is applied to the printing portion, it causes blurring. Therefore, the width W2 on the rear side of the support 4 in the squeegee movement direction is preferably set to a dimension that can secure a blank portion of the paste pool. Furthermore, since the end of the squeegee is loaded, it is necessary to separate it from the printing unit, and in order to secure a margin in the width direction of the squeegee, the width D in the direction orthogonal to the squeegee movement direction of the opening 4a of the support 4 is Desirably, the dimensions are shorter than the overall length of the squeegee.

The support 4 is formed of a high-strength metal plate that has a smaller elongation in the plane direction during squeezing and a smaller displacement in the thickness direction than the printing screen 3. In particular, it is preferable to use a metal plate having a thickness that can maintain an undeformed state against the tension of the printing screen 3. The material and thickness of the support 4 have a Young's modulus of 70 GPa or more and 640 GPa or less, preferably a thickness of 0.1 mm or more and 3 mm or less, a Young's modulus of 150 GPa or more and 430 GPa or less, and a thickness of 0.1 mm or more and 1 mm or less. preferable. The thermal expansion coefficient of the support 4 is preferably 1 × 10 ⁻⁶ / ° C. or more and 23 × 10 ⁻⁶ / ° C. or less, more preferably 4 × 10 ⁻⁶ / ° C. or more and 11 × 10 ⁻⁶ / ° C. or less. As such a high-strength and low-thermal-expansion metal plate, for example, a stainless plate, a copper plate, an aluminum plate, a super invar, a cemented carbide, a high-strength steel plate and the like can be generally used.

The function of the support in the conventional combination screen plate is to minimize the deformation of the printing screen by bearing the deformation of the plate that occurs during printing by its own elongation. On the other hand, the function of the support in the combination screen plate of the present invention is not to bear deformation during printing by its own elongation, but to reinforce the periphery of the printing screen and minimize deformation of the printing screen. It is. Therefore, a high-strength metal plate is used for the support 4. The thickness of the support 4 is arbitrary, but when the end of the squeegee is designed to slide on the support 4, the space at the step between the support 4 and the printing screen 3 is reduced. In order to suppress damage to the squeegee, the thickness of the support 4 is preferably 3 mm or less, particularly 1 mm or less. The thickness is preferably 0.1 mm or more so that deformation due to sliding friction with the squeegee can be suppressed. In addition, it is also possible to suppress damage to the squeegee by filling the stepped portion with an adhesive or the like.

Table 1 is a comparison table of the characteristics of each material when using a SUS430 plate, Al, Invar, cemented carbide as an example of the support 4 and using a polyester screen that is a conventional general support. It is. In the case of a polyester screen, since the shape is a net, the Young's modulus is low, the thermal expansion coefficient and the humidity expansion coefficient are large, the coordinate reproducibility is low, and the effect of suppressing load deformation, temperature and humidity change is low. On the other hand, when the material of the support is SUS430 plate, Al, Invar material, cemented carbide, the Young's modulus is several tens of times that of the polyester screen, the thermal expansion coefficient and the humidity expansion coefficient are small, and the shape is Since it is plate-shaped, the coordinate reproducibility is high, and the effect of suppressing load deformation, temperature change and humidity change is high. As a result, there is an effect that the printing accuracy is increased.

FIG. 2 shows a SUS430 plate (thickness 0.4 mm), a stainless screen (# 150-61: wire diameter 61 μm mesh number 150 / inch), a resin screen (polyester screen # 230-48: wire diameter 48 μm mesh number 230 pieces / inch). inch) SS curve. As can be seen from FIG. 2, the strength of the SUS430 plate is overwhelmingly higher than that of the stainless steel screen of the same material as well as the resin screen. Therefore, the deformation of the support during printing, and hence the deformation of the printing screen can be effectively suppressed.

FIG. 3 shows a comparison of the coordinate restoration properties before and after printing between the conventional structure and the structure of the present invention. In the conventional structure, a polyester screen having an outer dimension of 320 mm □, an inner dimension of 210 mm □, and # 230-48 was used as a support, and a tungsten screen was used as a printing screen. In the structure of the present invention, a SUS430 plate having an outer dimension of 320 mm □, an inner dimension of 210 mm □, and a thickness of 0.4 mm was used as the support, and the same tungsten screen as that of the conventional example was used as the printing screen. The printing method was a contact method, and the conditions were the same. The coordinate deviation is a difference between coordinates before and after printing.

As is apparent from FIG. 3, the coordinate deviation before and after printing is ± 5 μm in the conventional structure, and the tendency of the deviation is scattered over the entire circumference. On the other hand, the coordinate shift of the structure of the present invention was ± 2 μm, and the coordinate position was close to the initial position. As a result, it can be seen that when the SUS430 plate is used as a support, the coordinate restoration before and after printing is improved as compared with the conventional case.

FIG. 4 shows a comparison of the coordinate restoration characteristics due to temperature and humidity changes between the conventional structure and the structure of the present invention. The screen plate used is the same as in FIG. In the case of the conventional structure, the deformation due to temperature change is 1.4 μm / ° C. · 68 mm, the deformation due to humidity change is −2.1 μm / 10% · 68 mm, and the deformation is non-linear. In the structure, the deformation due to temperature change was 1.2 μm / ° C. · 68 mm, the deformation due to humidity change was −1.2 μm / 10% · 68 mm, and the deformation was also linear. Therefore, by changing the support from a polyester screen to a SUS430 plate, the support became a low thermal expansion / non-hygroscopic material, and distortion due to changes in temperature and humidity could be suppressed.

FIG. 5 shows an example of a printing apparatus according to the present invention. In this example, the combination screen plate 1 shown in FIG. 1 is applied to a contact type printing apparatus. On the upper side of the combination screen plate 1, a squeegee 10 that slides on the printing screen 3 and the support 4 is attached to a moving mechanism 11 that moves in the horizontal direction. The squeegee 10 is in pressure contact with the printing screen 3 and the support 4 obliquely with a predetermined printing pressure. The total length of the squeegee 10 (the length in the direction perpendicular to the paper surface) is desirably larger than the width of the opening 4a of the support 4 (D in FIG. 1). In this case, since the end of the squeegee 10 that is most loaded slides on the support 4, the load on the printing screen 3 can be reduced. Further, the width on the front side of the support 4 in the squeegee movement direction (W1 in FIG. 1) is the run distance of the squeegee until the paste rolling is stabilized, and the width on the rear side of the support 4 in the squeegee movement direction (in FIG. 1). W2) is the margin of the paste pool.

On the lower side of the combination screen plate 1, a printing stage 12 having an outer peripheral surface 12a having an arcuate cross section is disposed. The dimension in the width direction of the printing stage 12 (dimension in the direction perpendicular to the paper surface) is larger than the width D of the opening 4 a of the support plate 4. On the outer peripheral surface of the stage 12, a printed material (not shown) such as a ceramic green sheet is adsorbed and held. The stage 12 is connected to a rotation mechanism (not shown) so as to rotate in the direction of the arrow in synchronization with the movement of the squeegee 10 while bringing the surface of the printing material into contact with the position corresponding to the tip position of the squeegee 10 on the back surface of the printing screen 3. It is attached. Note that the outer circumferential surface having an arcuate cross section may be an elliptical arcuate outer circumferential surface. Since the detailed configuration is as described in Patent Document 4, it is omitted here.

In FIG. 5, a two-dot chain line indicates a printing start state, a one-dot chain line indicates an intermediate state, and a solid line indicates an end state. The squeegee 10 moves horizontally in the direction of the arrow while pressing the paste (printing ink) P against the printing screen 3. Since the top part of the arcuate outer peripheral surface 12a of the stage 12 is in partial contact with the position corresponding to the tip position of the squeegee 10 on the back surface of the printing screen 3, the stage 12 is peeled off from the stage 10 due to the viscosity of the paste P. The elongation of the printing screen 3 can be suppressed. In addition, since the periphery of the printing screen 3 is supported by the high-strength support body 4, the elongation in the plane direction of the printing screen 3 due to friction with the squeegee 10 can be suppressed or prevented.

In this way, the stage 12 rotates while partially contacting the position corresponding to the tip position of the squeegee 10 on the back surface of the printing screen 3, so the printing screen 3 when the printing screen 3 and the stage 12 are peeled off. Can be effectively suppressed. Further, since the periphery of the printing screen 3 is held by the support 4 that is a high-strength metal plate, it is possible to suppress the elongation in the plane direction of the printing screen 3 due to friction with the squeegee 10. Furthermore, the elongation in the thickness direction of the printing screen 3 which is a feature of contact printing can also be suppressed.

FIG. 6 shows the result of screen printing using the printing apparatus shown in FIG. 5 under the following conditions. The plate structure and printing conditions are as follows.
Frame: Aluminum frame with outer dimension 364 mm, inner dimension 320 mm □, thickness 16.5 mm Support: SUS430 plate with outer dimension 364 mm □, inner dimension 210 mm □, thickness 0.4 mm Printing screen: High mesh tungsten screen (# 430 -13: Wire diameter 13μm Number of meshes 430 / inch)

Under the above conditions, contact type screen printing was performed using a stage having an arcuate cross section, and the required printing accuracy of ± 15 μm could be stably achieved for multilayer products. Therefore, the effect of the combination screen plate according to the present invention was proved. By using such a high-accuracy combination screen plate, high-density printing is possible, and high-performance multilayer products can be manufactured.

The above embodiments are only a few examples of the present invention, and can be modified without departing from the spirit of the present invention. In the above embodiment, SUS430 is used as the material of the support, but other stainless steel plates may be used, and other metal plates such as high-strength steel plates, aluminum plates, copper plates, and other alloys are used. You can also The thickness of the support is preferably set according to the Young's modulus.

In the printing apparatus of FIG. 5, a fan-shaped stage is used as the stage, but a bowl shape or a cylindrical stage may be used as long as the stage has a convex curved surface. Furthermore, the combination screen plate of the present invention is not limited to the contact-type printing method using a stage having a convex curved surface as shown in FIG. 5, but is also applicable to line-peeling printing, and further to a contact-type printing method using a flat plate stage. Is also applicable.

DESCRIPTION OF SYMBOLS 1 Combination screen plate 2 Frame 3 Printing screen 4 Support body 4a Opening part 10 Squeegee 12 Stage 12a Arc-shaped outer peripheral surface P Paste

Claims (7)

In a combination printing screen for contact printing comprising: a frame; a printing screen; and a support having an inner peripheral portion joined to an outer peripheral portion of the printing screen and an outer peripheral portion fixed to the frame.
The printing screen is a metal screen;
The contact printing combination screen plate for contact printing, wherein the support is formed of a high-strength metal plate that has a smaller elongation in the plane direction during squeezing and a smaller displacement in the thickness direction than the printing screen. The printing screen is bonded to the support with a predetermined tension;
The combination screen plate for contact printing according to claim 1, wherein the support is a metal plate having a thickness capable of maintaining an undeformed state against the tension of the printing screen. 3. The combination screen plate for contact printing according to claim 1, wherein the support is a metal plate having a Young's modulus of 70 GPa or more and 640 GPa or less and a thickness of 0.1 mm or more and 3 mm or less. The combination screen plate for contact printing according to claim 3, wherein the support is a metal plate having a thickness of 0.1 mm or more and 1 mm or less. The combination screen plate for contact printing according to claim 1, wherein the support is a metal plate having a thermal expansion coefficient of 1 × 10 ⁻⁶ / ° C. or more and 23 × 10 ⁻⁶ / ° C. or less. . The combination screen plate for contact printing according to any one of claims 1 to 5, wherein the printing screen is bonded to a printing stage side of the support. A combination screen plate for contact printing according to any one of claims 1 to 6,
A squeegee that moves horizontally while pressing the paste supplied on the printing screen of the combination screen plate;
Synchronizing with the movement of the squeegee while having an outer peripheral surface with an arc-shaped cross section and bringing the surface of the printing material adsorbed on the outer peripheral surface into contact with a position corresponding to the tip position of the squeegee on the back surface of the printing screen A printing apparatus comprising: a rotating printing stage.

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