JP2009101665A - Mask for screen printing, screen printing apparatus and screen printing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mask for screen printing capable of solder-printing with different thicknesses by one printing even if a conventional screen printing apparatus is used. <P>SOLUTION: The mask for screen printing includes a flat plate-shaped mask 40 with through-holes 40w, 40x, 40y and 40z penetrating in the thickness direction, and prints solder paste S through the through-holes on the surface of an article 1 to be printed covered by the flat plate-shaped mask 40. The flat plate-shaped mask 40 is composed of a mask body 41 in which first through-holes 40w, 40x and 40y and a second through-hole 41z with a length shorter in the thickness direction than lengths of the first through-holes, and a mask movable part 42 which can slidably move on the surface of the mask body 41 in the face direction, and in which a movable through-hole 42z forming a through-hole 40z by communicating with the second through-hole 41z is formed. The mask movable part 42 is slidably moved to cut the solder paste Sz filling the through-hole 40z by rubbing with the inner wall face of the movable through-hole 42z. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a mask, a printing apparatus, and a printing method used when a solder paste is applied to a printed wiring board or the like by screen printing.

  Generally, when surface mounting of an electronic component on a printed wiring board is performed by a reflow soldering method, a solder paste (also referred to as “cream solder”) is applied to the printed wiring board in advance by a screen printing method. A general procedure for applying the solder paste by the screen printing method will be described with reference to FIG. FIG. 1 is an explanatory view schematically showing a general procedure for applying a solder paste by a screen printing method, wherein (i) to (iii) each show a part of a cross section in the thickness direction of a printed wiring board. . In FIG. 1, a printed wiring board 10 is formed on an insulating substrate 11, a conductor pattern 12 formed of a conductive material such as copper on the front and back surfaces of the insulating substrate 11, and a conductor pattern 12 so as to cover the conductor pattern 12. And a solder resist 13. The solder resist 13 is made of resin, and part of the conductor pattern 12 (footprints 12a and 12b) that needs to be soldered is exposed from 13a and 13b.

  In order to apply the solder paste to the footprints 12a and 12b by the screen printing method, a screen printing mask 20 having through holes 20a and 20b penetrating in the thickness direction is placed on the surface of the printed wiring board 10 (FIG. 1). (I)). At this time, at least a part of each of the footprints 12a and 12b is exposed from the through holes 20a and 20b. Next, the solder paste S is filled into the space composed of 12a and 13a and the space composed of 12b and 13b (FIG. 1 (ii)). The solder paste S is filled in each space by a squeegee 30, for example. Since the squeegee 30 moves in parallel with the screen printing mask 20 in the direction of the arrow while being pressed against the screen printing mask 20, the surface of the screen printing mask 20 is smoothed. Thereafter, the screen printing mask 20 is removed from the printed wiring board 10. Solder pastes Sa and Sb are printed on the surface of the printed wiring board 10 (on the footprints 12a and 12b) (FIG. 1 (iii)).

  And although not shown in figure, after FIG. 1 (iii), it heats in the state which mounted the components for surface mounting on printed solder paste Sa and Sb, and solder is melted (reflow method), and soldering is carried out. To obtain a printed circuit board on which components are mounted.

  In the screen printing method, a screen printing mask having a uniform thickness is generally used. A solder paste printed using a screen printing mask having a uniform thickness has a uniform thickness regardless of the opening area (opening ratio) of the through hole. However, the bonding strength between the leads and electrodes of the surface mounting component and the footprint of the printed wiring board depends on the amount of solder paste. Therefore, it is necessary to adjust the printing amount of the solder paste on the footprint to an appropriate amount according to the type of the surface mounting component.

  For example, the amount of solder paste printed on one footprint can be increased or decreased by adjusting the opening area (opening ratio) of the through hole of the screen printing mask. However, in recent years, with the miniaturization of electronic devices, electronic components mounted on a printed wiring board have been miniaturized and densified, and the size of footprints and the interval between adjacent footprints are becoming smaller. Therefore, the adjustment by the aperture ratio has a limit.

  Therefore, Patent Document 1 discloses a method of printing solder pastes having different thicknesses by preparing two masks for screen printing and performing screen printing twice using each mask. First, the solder paste is printed using the first mask. Next, the second mask having a through-hole is superimposed on the first mask at a position corresponding to the solder paste on the land (footprint) requiring a thickness, and the solder paste is printed. Therefore, when further thickness is required, it is necessary to perform screen printing three times or more.

  Although the purpose is different from Patent Document 1, Patent Document 2 also describes that screen printing is performed with at least two masks overlapped. In Patent Document 2, after filling a through hole with a solder paste in a state where a plurality of masks are superposed on the surface of a non-printed material, the masks are sequentially separated. Each mask is separated so that the solder paste is not scraped off in the same way as when a normal mask is removed from the surface of the non-print.

Patent Document 3 discloses a printing method using screen printing masks having partially different thicknesses. Solders with different thicknesses by one printing using one screen printing mask by making the periphery of the through hole of the screen printing mask corresponding to the portion where the solder paste is to be printed thicker than the other portions. The paste can be printed.
Japanese Patent Laid-Open No. 4-276692 JP 2007-168127 A Japanese Patent Laid-Open No. 11-74638

  As described above, in the method described in Patent Document 1, in order to print solder pastes having different thicknesses, screen printing must be performed twice or more. However, if the number of screen printings is large, there is a problem that printing tends to shift. On the other hand, in the method described in Patent Document 3, solder pastes having different thicknesses can be printed by one printing. However, since the screen printing masks having partially different thicknesses have irregularities on the surface, the squeegee may not move smoothly when the solder paste is filled into the through holes. In such a case, even if the squeegee is moved under the same conditions as in the conventional case, there is a possibility that the solder paste is not satisfactorily filled in all the through holes. In such a case, it is necessary to change not only the moving speed and pressing pressure of the squeegee but also the material and shape of the squeegee and the mounting angle, and thus there is a problem that the conventional screen printing apparatus cannot be used as it is.

  Therefore, an object of the present invention is to provide a screen printing mask that can print solder prints having different thicknesses by one printing even when a conventional screen printing apparatus is used. It is another object of the present invention to provide a screen printing apparatus having the screen printing mask and a screen printing method using the screen printing mask.

The screen printing mask of the present invention includes a flat mask having a plurality of through holes penetrating in the thickness direction, and screen printing is performed by printing solder paste on the printing surface covered with the flat mask through the through holes. A mask for a flat plate,
A mask body in which a first through hole which is a part of the plurality of through holes and a second through hole having a length in the thickness direction shorter than the first through hole are formed,
A mask movable portion that is slidable in a surface direction on the surface of the mask body, and has a movable through hole that communicates with the second through hole and forms the remainder of the plurality of through holes;
The mask movable part is slid to slide the solder paste filled in the second through hole and the movable through hole on the inner wall surface of the movable through hole.

The screen printing apparatus of the present invention is a printing apparatus having the screen printing mask of the present invention. The screen printing apparatus of the present invention is
A flat mask having a plurality of through holes penetrating in the thickness direction, the flat mask is
A mask body in which a first through hole which is a part of the plurality of through holes and a second through hole having a length in the thickness direction shorter than the first through hole are formed,
A mask movable portion that is slidable in a surface direction on the surface of the mask body, and has a movable through hole that communicates with the second through hole and forms the remainder of the plurality of through holes;
A screen printing mask comprising:
A mask fixing means for fixing the screen printing mask to the surface of the substrate;
A solder paste filling means for filling the space defined by the surface of the substrate and the inner wall surface of the through hole with a solder paste;
With the mask main body fixed to the substrate, the mask movable part is slid to slide the solder paste filled in the second through hole and the movable through hole on the inner wall surface of the movable through hole. Solder paste scraping means;
Mask separating means for separating the substrate and the screen printing mask;
It is characterized by providing.

The screen printing method of the present invention is a method for performing screen printing using the screen printing mask of the present invention. The screen printing method of the present invention comprises:
A flat mask having a plurality of through holes penetrating in the thickness direction, the flat mask is
A mask body in which a first through hole which is a part of the plurality of through holes and a second through hole having a length in the thickness direction shorter than the first through hole are formed,
A mask movable portion that is slidable in a surface direction on the surface of the mask body, and has a movable through hole that communicates with the second through hole and forms the remainder of the plurality of through holes;
A mask fixing step of fixing the screen printing mask comprising the following to the surface of the printing material in a state where the second through hole and the movable through hole are in communication with each other;
A solder paste filling step of filling a space defined by the surface of the substrate and the inner wall surface of the through hole with a solder paste;
With the mask main body fixed to the substrate, the mask movable part is slid to slide the solder paste filled in the second through hole and the movable through hole on the inner wall surface of the movable through hole. Solder paste cutting process,
A mask separating step for separating the substrate and the screen printing mask;
It is characterized by including.

The screen printing mask of the present invention comprises a mask body in which a first through hole and a second through hole are formed, and a movable mask in which a movable through hole is formed,
The mask body has a stepped portion having a surface on which the movable mask can slide, the first through hole is formed in a portion where the mask body and the movable mask do not overlap, and the second through hole is A screen printing mask characterized in that the mask main body and the movable mask are formed in an overlapping portion, and the movable through hole is formed so as to communicate with the second through hole. You can also.

  The screen printing mask of the present invention includes a flat mask composed of a mask body and a mask movable part. The mask main body has a first through hole that is a part of a plurality of through holes of the flat mask and a second through hole that is shorter in the thickness direction than the first through hole. That is, the mask body is partially different in thickness. On the other hand, the mask movable part has a movable through hole that communicates with the second through hole and forms the remainder of the plurality of through holes. By combining the mask main body and the mask movable part, the non-uniformity of the thickness of the mask main body is alleviated, so that the surface of the flat plate mask becomes substantially flat. As a result, the solder paste can be filled into the plurality of through holes of the flat mask by the conventional method using the conventional apparatus. For example, when filling a through-hole with a solder paste using a squeegee, the squeegee can move smoothly on the surface of the flat mask without setting special conditions.

  And if it is the mask for screen printing of this invention, the solder paste from which thickness differs will be printed only by filling the several through-hole which a flat mask has with the solder paste once. In the screen printing mask of the present invention, the mask movable portion is slidable in the surface direction on the surface of the mask main body. When the mask movable part is slid, the movable through hole is moved together with the mask movable part, so that the solder paste filled in the second through hole and the movable through hole is slid off on the inner wall surface of the movable through hole. As a result, the solder paste remains on the printed surface by the thickness of the second through-hole, and as a whole, the portion where the solder paste is printed thickly through the first through-hole and the solder paste through the second through-hole. A thinly printed portion is formed.

  The best mode for carrying out the mask for screen printing, the screen printing apparatus and the screen printing method of the present invention will be described below.

[Mask for screen printing]
The screen printing mask of the present invention includes a flat mask having a plurality of through holes penetrating in the thickness direction. A solder paste is printed through a through hole on a surface to be printed (a surface such as a printed wiring board) covered with a flat mask. If the printing surface is the surface of the printed wiring board, the through hole is arranged corresponding to the position of each footprint of the printed wiring board. The flat mask includes a mask body and a mask movable part.

  The mask body is formed with a first through hole that is a part of a plurality of through holes of the flat mask and a second through hole that is shorter in the thickness direction than the first through hole. The mask body is partially different in thickness. This is because the length in the thickness direction is different between the first through hole and the second through hole, and the thickness of the peripheral part of the first through hole and the peripheral part of the second through hole is different. There is no particular limitation on the position of the first through hole and the second through hole. On the printed surface, the first through hole is a position where the solder paste is to be printed thickly, and the second through hole is a position where the solder paste is desired to be printed thinly. Are arranged on the flat mask so as to correspond to each other. This is because, as will be described in detail later, the solder paste is printed on the printing surface with a thickness corresponding to the length of the first through hole and the second through hole in the thickness direction.

  The mask body may be manufactured by processing a flat plate having a uniform thickness, but preferably comprises a flat base mask and a flat fixed mask piece superimposed on the surface of the base mask. A thick part is formed at the part where both overlap. Therefore, by changing the size of the base mask and the fixed mask piece and the way of overlapping each other, a mask main body having a partially different thickness can be easily formed. Two or more fixed mask pieces may be superimposed on the base mask. Two or more sheets may be arranged on the same surface of the base mask, or two or more sheets may be superimposed on the surface of the base mask in the thickness direction. By superposing two or more fixed mask pieces on the surface of the base mask in the thickness direction, the thickness of each part of the mask body can be changed variously. As a result, it is possible to print a plurality of types of solder paste with a single flat mask.

  As will be described in detail later, the solder paste is printed on the printing surface with a thickness corresponding to the length of the first through hole and the second through hole in the thickness direction. The length of the first through hole and the second through hole in the thickness direction depends on the thickness of each part of the mask body. Therefore, when it is desired to set the thickness of the solder paste to be printed to the maximum thickness Tk and the minimum thickness Tn, it is necessary to use a mask body having the thickest portion of thickness Tk and the thinnest portion of thickness Tn. is there.

  What is necessary is just to select suitably the magnitude | size and cross-sectional shape of the 1st through-hole and 2nd through-hole in planar view of a flat mask according to the magnitude | size and shape of the solder paste to print. Therefore, if the surface to be printed is the surface of the printed wiring board, it may be appropriately selected according to the size and shape of the footprint. Further, the number of first through holes and second through holes is not limited.

  The mask movable portion is slidable in the surface direction on the surface of the mask main body, and is formed with a movable through hole that communicates with the second through hole of the mask main body and forms the remaining portions of the plurality of through holes. In other words, the plurality of through holes of the flat mask include a first through hole and a through hole in which the second through hole and the movable through hole communicate with each other. When the movable part of the mask is slid, the movable through hole is also slid. Therefore, when the solder paste is filled in the second through hole and the movable through hole that communicate with each other, the solder paste is scraped off on the inner wall surface of the movable through hole. It is done.

  The shape of the mask movable portion is not particularly limited as long as it is a shape that can be slid in the surface direction on the surface of the mask main body. Preferably, when the second through hole of the mask body and the movable through hole of the mask movable part are communicated with each other, the surface of the thickest part of the mask body and the surface of the mask movable part are positioned on the same plane. Thus, the surface of the flat mask becomes substantially flat. Moreover, there is no restriction | limiting in the number of mask movable parts which one flat mask has.

  The mask movable part is preferably composed of a flat movable mask piece. One movable mask piece may be used alone, or two or more movable mask pieces may be overlapped in the thickness direction. When two or more movable mask pieces are used in the thickness direction, the movable mask pieces may be slid integrally by fixing the movable mask pieces to each other, or may be individually slidable one by one. Further, two or more movable mask pieces having different sizes may be overlapped in the thickness direction. What is necessary is just to select the thickness of a movable mask piece suitably according to the shape and dimension of a mask main body.

  The shape of the movable through hole is not particularly limited as long as it communicates with the second through hole of the mask body when the solder paste is filled in the through hole of the flat mask. Since the solder paste filled in the movable through hole is slid by the movement of the mask movable portion and is not printed on the printing surface, the sectional shape of the movable through hole may not be the same as that of the second through hole. For example, it may be a movable through hole having a large-sized opening communicating with two or more second through holes. The movable through hole preferably has an inner wall surface that is inclined with respect to the thickness direction. The inner wall surface of the movable through hole slides the solder paste as the mask movable portion slides. Therefore, for example, by inclining the inner wall surface in a direction that slides on the basis of the thickness direction, the solder paste filled in the movable through hole is pressed against the second through hole on the inner wall surface along with the movement of the mask movable portion. Further, by inclining the inner wall surface in a direction opposite to the direction of scraping with respect to the thickness direction, it becomes difficult for solder to enter between the mask movable portion and the mask main body.

  Although there is no particular limitation on the material of the mask movable part, it is preferable to be made of a metal material. This is because the metal material has a rigidity capable of maintaining the shape during sliding movement even if it is a thin plate corresponding to the thickness Tn of the thinnest portion of the mask body. Moreover, not only the mask movable part but the whole flat mask may be made of metal. If the flat mask is made of metal, it is easy to process the mask body and the mask movable part and the through hole. The communication hole may be processed in a state where the mask main body (which may be a base mask and a fixed mask piece) and the mask movable portion (which may be a movable mask piece) are overlapped. If the flat mask is made of metal, a through hole may be formed by a laser.

  Further, the flat mask can also be regarded as being composed of at least two thin masks having a plurality of through holes penetrating in the thickness direction by overlapping. Each of the thin plate masks preferably comprises a base mask and one or more partially movable masks. The partially movable mask is superimposed on the surface of the base mask in the thickness direction. The partial movable mask includes a fixed mask piece and a movable mask piece. A part of the movable mask piece is divided from the partial movable mask to form a movable through hole. The movable mask piece can slide in the surface direction on the surface of the adjacent thin plate mask. That is, a simple configuration in which a plurality of plate materials are prepared, and a position to be divided is appropriately selected and overlapped can be easily formed into a desired shape even if the flat mask has a complicated shape.

  Furthermore, the screen printing mask of the present invention preferably has guide means for guiding the movement of the mask movable portion. For example, a groove in which the peripheral edge of the mask movable portion is fitted as a guide means may be formed on the plate frame holding the flat mask, and slid along the groove. Further, since the mask body is partially different in thickness, a step portion is formed around the opening of the second through hole. By fitting the step portion and the mask movable portion, the movement of the mask movable portion is guided to the step portion. In other words, the guide means may also be used in the step portion of the mask body.

[Screen printing device]
The screen printing apparatus of the present invention is a printing apparatus having the screen printing mask of the present invention already described in detail. The screen printing apparatus of the present invention mainly comprises the screen printing mask of the present invention, a mask fixing means, a solder paste filling means, a solder paste scraping means, and a mask separating means.

  The mask fixing means is means for fixing the screen printing mask to the surface of the substrate. If it is a mask fixing means in which a screen printing mask is disposed above the stage on which the substrate is placed, the screen printing mask may be lowered while the stage is fixed, or the screen printing mask is fixed. The stage may be raised in the state. In any case, it is sufficient that the mask body (base mask) is placed on the surface (printed surface) of the printed material. At this time, the mask fixing means may be fixed so that the substrate to be printed and at least the mask body do not shift. More preferably, the mask fixing means includes an alignment means for aligning the substrate to be printed and the flat mask.

  The solder paste filling means is means for filling the solder paste in a space defined by the surface of the printing material and the inner wall surface of the through hole. The solder paste filling means preferably includes a squeegee that moves in parallel on the screen printing mask while pressing the solder paste placed on the screen printing mask. The squeegee may be of a material and shape conventionally used in solder paste screen printing devices. Since the screen printing mask of the present invention includes a flat mask composed of a mask main body and a mask movable portion, the length in the thickness direction differs between the first through hole and the second through hole, and the mask main body has a partial thickness. This is because unevenness of the thickness of the flat plate mask as a whole is leveled even if they are different. A general plate-like metal or rubber can be used as the squeegee.

  The solder paste scraping means slides the mask movable portion while the mask main body is fixed to the printing material, and scrapes the solder paste filled in the second through hole and the movable through hole on the inner wall surface of the movable through hole. Means. If the solder paste filling means slides the movable part of the mask while the solder is filled in all the through holes of the flat mask, the second through hole and the movable through hole are filled. The solder paste is naturally scraped off on the inner wall surface of the movable through hole. The solder paste scraping means may be a device that mechanically pulls out the mask movable portion from the stepped portion.

  The mask separating means is a means for separating the printing material and the screen printing mask. The screen printing mask should not be slid in the surface direction like the mask moving part, but must be moved and separated in a direction that does not adversely affect the solder paste printed on the surface to be printed, such as the thickness direction. There is. As described above, the mask fixing means in which the screen printing mask is disposed above the stage on which the substrate is placed can be easily separated by lowering the stage or raising the screen printing mask. Further, the screen printing mask may be separated from the printing surface in order from one end of the screen printing mask.

[Screen printing method]
The screen printing method of the present invention is a method for performing screen printing using the above-described screen printing mask of the present invention. The screen printing method of the present invention mainly includes a mask fixing step, a solder paste filling step, a solder paste scraping step, and a mask separation step.

  The mask fixing step is a step of fixing the screen printing mask to the surface of the printing material in a state where the second through hole of the mask main body and the movable through hole of the mask movable portion are in communication. The mask main body needs to be fixed so as not to be displaced from the printing surface until it is separated from the printing material. On the other hand, the mask movable part may be fixed to the mask main body and cannot be moved until it is slid.

  The solder paste filling step is a step of filling the solder paste into a space defined by the surface of the printing material and the inner wall surface of the through hole. For example, by placing the solder paste on the screen printing mask and pressurizing the solder paste with a squeegee that moves in parallel on the screen printing mask, the solder paste can be uniformly filled in all the through holes. In addition, the displacement of the mask movable part from the mask body is suppressed by moving the squeegee in the same direction as the direction in which the mask movable part cannot slide.

  In the solder paste scraping process, the mask movable part is slid in a state where the mask body is fixed to the printing material, and the solder paste filled in the second through hole and the movable through hole is scraped off on the inner wall surface of the movable through hole. It is a process. The mask movable portion after sliding movement may be separated from the mask main body, or may be in a state of being placed on the mask main body as long as the second through hole and the movable through hole do not communicate with each other. In addition, since the solder paste with which the movable through-hole was filled is not printed on the surface of a to-be-printed material, it can collect | recover and can be reused.

  The mask separation step is a step of separating the printing material and the screen printing mask. If the mask movable part is separated from the mask body, only the mask body may be separated from the substrate.

  The embodiments of the screen printing mask, the screen printing apparatus, and the screen printing method of the present invention have been described above. However, the screen printing mask, the screen printing apparatus, and the screen printing method of the present invention are limited to the above embodiments. is not. The present invention can be implemented in various forms without departing from the gist of the present invention, with modifications and improvements that can be made by those skilled in the art.

  Below, the mask for screen printing, the screen printing apparatus, and the screen printing method of this invention are demonstrated concretely using FIGS.

  2 and 3 are explanatory views schematically showing a solder paste printing method using the screen printing mask of the present invention. FIG. 2 is a plan view of a flat mask of the mask for screen printing of the present invention, and FIG. 3 shows a cross section taken along the line A-A 'of FIG.

  The flat mask 40 has through holes 40w, 40x, 40y and 40z penetrating in the thickness direction, and includes a mask main body 41 and a mask movable portion. The flat mask 40 has a rectangular shape as a whole, and the cross-sectional shape of each through hole is also a rectangular shape.

  The mask body 41 includes through holes 40w, 40x, and 40y as first through holes, and a second through hole 41z that is shorter in the thickness direction than the first through hole. Therefore, the mask body 41 includes a thick portion having the first through holes 40w, 40x, and 40y and a thin portion having the second through hole 41z, and a step portion 41t in which the second through hole 41z opens on the surface. It has. The 2nd through-hole 41z is a part of through-hole 40z which is one of the four through-holes which the flat mask 40 has.

  The mask movable part 42 is fitted into the step part 41t of the mask main body 41 to constitute the flat mask 40 as a whole. The mask movable part 42 has a movable through hole 42z which is a part of the through hole 40z which is one of the four through holes of the flat mask 40. The movable through hole 42z communicates coaxially with the second through hole 41z in a state where the mask movable portion 42 is fitted to the stepped portion 41t, and the second through hole 41z and the movable through hole 42z form a through hole 40z.

  The mask movable part 42 is slidable in the surface direction while being fitted to the step part 41t. The mask movable portion 42 slides and moves at least in sliding contact with the surface of the step portion 41t (indicated by reference numeral t1) where the second through hole 41z opens. For example, when the mask movable portion 42 is slid in the direction of the arrow in FIG. 2, the mask movable portion 42 is in sliding contact with the surface t1 of the step portion 41t in which the second through hole 41z is opened and rises from the surface. The sliding direction is guided in one direction by making sliding contact with the surface t2 defining the portion 41t.

  In order to print the solder paste on the printing surface using the screen printing mask having the flat mask 40, first, the printing material 1 is placed on the stage 9 of the screen printing apparatus. Next, the surface (printed surface) of the substrate 1 is covered with a flat mask 40 so that each through hole is at a predetermined position (FIG. 3 (I) mask fixing step). At this time, the mask main body 41 is fixed so that the position of the mask main body 41 relative to the substrate 1 is not changed by the movement of the squeegee 30 in the subsequent solder paste filling step. On the other hand, the mask movable part 42 is fitted to the step part 41t in a state in which the mask movable part 42 is slidable in the surface direction. That is, in this state, the second through hole 41z and the movable through hole 42z are coaxially connected to form a through hole 40z.

  Next, the solder paste S is filled into the through holes 40w, 40x, 40y, and 40z using the squeegee 30 (FIG. 3 (II) solder paste filling step). Let the solder paste filled in each through hole be Sw, Sx, Sy, Sz (Sw and Sx are not shown). The squeegee 30 translates on the flat mask 40 in the direction of the arrow while being pressed against the flat mask 40. The solder paste S is filled in the space defined by the inner wall surface of each through hole and the printing surface without any gap, and the surplus is scraped off by the squeegee 30 to smooth the surface of the flat mask 40. In addition, since the moving direction of the squeegee is the same direction as the direction in which the mask movable portion 42 cannot slide, the displacement of the mask movable portion 42 from the mask main body 41 is suppressed.

After filling each through hole with the solder paste S, the mask movable portion 42 is slid (FIG. 3 (III) solder paste cutting process). When the mask movable part 42 is slid in the arrow direction, the solder paste Sz ′ filled in the movable through hole 42z out of the solder paste Sz filled in the through hole 40z moves together with the mask movable part 42. Due to the movement of the mask movable portion 42, a part of the solder paste Sz filled in the through hole 40z is slid off by the inner wall surface of the movable through hole 42z. As a result, the solder paste Sz ⁻ in the second through hole 41z remains on the surface of the substrate 1. On the other hand, the solder pastes Sw, Sx and Sy remain in the through holes 40w, 40x and 40y.

Thereafter, the substrate 1 and the flat mask 40 are separated (FIG. 3 (IV) mask separation step). Solder pastes Sw, Sx, Sy, Sz ⁻ are printed on the surface (printed surface) of the substrate 1. The solder pastes Sw, Sx and Sy have a thickness corresponding to the length in the thickness direction of the through holes 40w, 40x and 40y. On the other hand, solder paste Sz ^- thickness decreases by the thickness of the mask moving unit 42 than the thickness filled in the through-hole 40 z, corresponding to the length of the thickness direction of the second through-hole 41 z. That is, solder pastes having different thicknesses are printed on the printing surface.

  4 to 7 are explanatory diagrams schematically showing a solder paste printing method using the screen printing mask of the present invention, which is a modification of the flat mask. FIG. 4 is a perspective view of a thin plate mask constituting the screen printing mask of the present invention. 5 to 7 are cross-sectional views of two adjacent through holes.

  The flat mask 50 is composed of three thin masks (base mask 51, partially movable masks 52 and 53), and through holes 50w, 50x, 50y and 50z penetrating in the thickness direction by overlapping each other. It has. The three thin masks have a rectangular shape, and the cross-sectional shape of each through hole is also a rectangular shape.

  The base mask 51 has lower through holes 51w, 51x, 51y and 51z. The partial movable mask 52 has fixed through holes 52w, 52x, 52z and a movable through hole 52y, and the partial movable mask 53 has fixed through holes 53w and movable through holes 53x, 53y, 53z. Each of the lower through hole, the fixed through hole, and the movable through hole is a part of four through holes that the flat mask 50 has. Therefore, by overlapping the base mask 51 and the partial movable masks 52 and 53, the lower through hole, the fixed through hole, and the movable through hole communicate coaxially as shown in the figure.

  The base mask 51 is made of a single thin plate, and is fixed to the surface (printed surface) of the substrate 1 during screen printing. Then, the partially movable masks 52 and 53 are sequentially superimposed on the surface of the base mask 51 in the thickness direction. The partial movable mask 52 includes a fixed mask piece 52 ′ and a movable mask piece 52 ″. The fixed mask piece 52 ′ has fixed through holes 52w, 52x, and 52z. The movable mask piece 52 ″ has a movable through hole 52y. Are divided from the partially movable mask 52. The fixed mask piece 52 'is fixed at a predetermined position on the base mask 51, and the movable through hole 52y and the lower through hole 51y communicate with each other. The movable mask piece 52 ″ is arranged flush with the fixed mask piece 52 ′ on the base mask 51, and is slidable on the surface of the base mask 51. The partial movable mask 53 is also connected to the fixed mask piece 53 ′. It consists of a movable mask piece 53 ″. The fixed mask piece 53 'has a fixed through hole 53w. The movable mask piece 53 ″ is divided from the partial movable mask 53 including the movable through holes 53x, 53y and 53z. The fixed mask piece 53 ′ is fixed at a predetermined position on the partial movable mask 52. The movable mask. The piece 53 ″ is disposed on the partial movable mask 52 so as to be flush with the fixed mask piece 53 ′, and is slidable on the surface of the partial movable mask 52.

  The mask body (corresponding to the shaded portion in FIG. 4) is formed by the base mask 51 and the fixed mask pieces 52 ′ and 53 ′, and the movable mask portion (corresponding to the white portion in FIG. 4) is formed by the movable mask pieces 52 ″ and 53 ″. ) Can be considered to be configured. Accordingly, the through hole 50w (consisting of the lower through hole 51w and the fixed through holes 52w and 53w) is the first through hole, the lower through hole 51x and the fixed through hole 52x, or the lower through hole 51z and the fixed through hole 52z. A third through hole is formed by the lower through hole 51y as a hole and a shorter through hole.

  In order to print the solder paste on the printing surface using the screen printing mask having the flat mask 50, first, the printing material 1 is placed on the stage 9 of the screen printing apparatus. Next, the surface (printed surface) of the substrate 1 is covered with a flat mask 50 so that each through hole is at a predetermined position (FIG. 5 (I) mask fixing step). At this time, the base mask 51 is fixed so that the position with respect to the substrate 1 does not change in a later procedure. The fixed mask pieces 52 'and 53' are fixed to the adjacent thin plate masks. On the other hand, the movable mask pieces 52 ″ and 53 ″ are placed on the thin plate mask in a state in which the movable mask pieces 52 ″ and 53 ″ can slide in the surface direction. In this state, the lower through hole, the fixed through hole, and the movable through hole are coaxially connected to form through holes 50w, 50x, 50y, and 50z.

  Next, the solder paste S is filled into the through holes 50w, 50x, 50y, and 50z using a squeegee (FIG. 5 (II) solder paste filling step). The solder paste filled in each through hole is defined as Sw, Sx, Sy, Sz (Sw and Sx are not shown in FIG. 5). The solder paste S is filled in the space defined by the inner wall surface of each through hole and the printing surface without any gap, and the surplus is scraped off by the squeegee 30 to smooth the surface of the flat mask 50.

  After filling each through hole with the solder paste S, the movable mask pieces 52 "and 53" are sequentially slid.

First, the movable mask piece 53 ″ is slid and the solder pastes Sx, Sy and Sz filled in the through holes 50x, 50y and 50z are slid by the inner wall surfaces of the movable through holes 53x, 53y and 53z (FIG. 6: As a result, the solder paste Sx ⁻ , Sy ⁻ and Sz ^{− in the} fixed through hole 52y, the movable through holes 52x and 52z, and the lower through holes 51x, 51y and 51z are formed on the surface of the substrate 1. (Sx is not shown) remains, while solder paste Sw remains as it is in the through hole 50w.

Then, by sliding the movable mask member 52 ", movable through holes 52y and the lower through holes 51y solder paste filled in the Sy ^- a as possible sliding by the inner wall surface of the movable through holes 52y (FIG. 7 (IV) solder paste . sliding switching step) As a result, the surface of the substrate 1, solder paste ^Sy in the lower through hole 51 y ^- remains the other hand, the other through hole, solder paste Sw, Sx ^-. and Sz ^- is It remains as it is.

Thereafter, the substrate 1 is separated from the base mask 51 and the fixed mask pieces 52 ′ and 53 ′ (FIG. 7 (V) mask separation step). Solder pastes Sw, Sx ⁻ , Sy ⁻⁻ and Sz ⁻ are printed on the surface (printed surface) of the substrate 1. The solder paste Sw has a thickness as filled in the through hole 50w. On the other hand, the thicknesses of the solder pastes Sx ⁻ , Sy ⁻⁻ and Sz ⁻ are reduced by the thickness of the movable mask pieces 52 ″ and 53 ″ from the thickness filled in the through holes 50x, 50y and 50z. That is, solder pastes having different thicknesses are printed on the printing surface.

  Although the example in which the movable mask pieces 52 ″ and 53 ″ are separately slid and moved has been described, the movable mask pieces 52 ″ and 53 ″ can be fixed integrally with each other in advance so that the sliding movement can be performed at a time. Good.

  In the above specific examples, the shape of the flat mask is rectangular in plan view, but it may be a trapezoid, a triangle, a circle, or a shape in which a cutout is formed in a rectangle, in addition to a rectangle and a square. Further, the base mask and the partially movable mask do not need to have the same size, and the base mask may be made larger than the partially movable mask, and the mask movable portion may be placed on the base mask even after the slide movement. .

  Moreover, there is no limitation also in the shape of a through-hole, A circular may be sufficient besides a rectangle. In addition, the shape and size of the first through hole and the second through hole (the lower through hole and the fixed through hole or the third through hole) may be set according to the printing material. There is no limit. When filling the solder paste, all the through holes are filled with the solder paste without any gap, and the inner wall surface of the movable through hole passes through the opening of the second through hole, so that the solder paste is satisfactorily cut. In this case, as schematically shown in FIG. 8, one movable through hole may communicate with the plurality of second through holes. 8 is a plan view schematically showing the flat mask 60, and the lower figure is a side view schematically showing the flat mask 60. FIG. In FIG. 8, the flat mask 60 has through holes 60 w, 60 xz, and 60 y that penetrate in the thickness direction, and includes a mask main body 61 and a mask movable portion 62. The flat mask 60 has a rectangular shape as a whole, and the cross-sectional shape of each through hole is also a rectangular shape.

  The mask main body 61 has through holes 60w and 60y as first through holes, and second through holes 61x and 61z that are shorter in the thickness direction than the first through holes. Therefore, the mask body 41 includes a thick portion having the first through holes 60w and 60y and a thin portion having the second through holes 61x and 61z, and a step where the second through holes 61x and 61z open on the surface. It has a part 61t. The second through holes 61x and 61z are a part of the through hole 60xz that is one of the three through holes of the flat mask 60.

  The mask movable portion 62 is fitted into the step portion 61t of the mask main body 61 to constitute the flat mask 60 as a whole. The mask movable part 62 has a movable through hole 62xz that is a part of the through hole 60xz that is one of the three through holes of the flat mask 60. The movable through-hole 62xz communicates with the second through-holes 61x and 61z in a state where the mask movable portion 62 is fitted to the stepped portion 61t, and the second through-holes 61x and 61z and the movable through-hole 62xz are one through-hole 60xz. Make. By sliding and moving the mask movable portion 62 in the plane direction in the direction of the arrow in the lower diagram of FIG. 8, the solder paste Sxz filled in the through hole 60xz is scraped off by the inner wall surface of the movable through hole 62xz.

  Further, the inner wall surface of the movable through hole may be inclined with respect to the thickness direction. An example is shown in FIG. FIG. 9 is a cross-sectional view schematically showing a flat mask, and is a partially enlarged view near a through hole. The flat mask 70 includes a mask main body 71 and a mask movable portion 72, and has a through hole 70x penetrating in the thickness direction. The mask main body 71 has a second through hole 71x penetrating the front and back. The mask movable part 72 has a movable through hole 72x penetrating the front and back. Both are coaxially connected by being overlapped in the thickness direction to form a through hole 70x. The second through hole 71x has a constant rectangular cross section in the surface direction or the thickness direction. On the other hand, the movable through hole 72x has an inclined surface P inclined with respect to the thickness direction. The inclined surface P inclines in a direction (sliding direction indicated by an arrow in the lower diagram of FIG. 9) that slides on the basis of the thickness direction. When the mask movable portion 72 slides, the solder paste filled in the movable through hole 72x is pressed against the second through hole 71x on the inclined surface P as the mask movable portion 72 moves. That is, the inclined surface P plays the role of a squeegee in the solder paste scraping process.

  In the above specific example, the number of through-holes is set to four for simplification of description. However, the number of through holes may be two or more.

  In the flat masks 40 and 60 described above, the stepped portions 41t and 61t are L-shaped in cross-section. Therefore, depending on the sliding direction of the mask movable portions 42 and 62, the sliding direction of each mask movable portion varies depending on the step. Guided in a predetermined direction by the unit. In particular, when it is desired to guide the sliding direction of the mask movable part in a fixed direction, it is preferable to use both the step part and the guiding means. FIG. 10 is a plan view showing a modification of the flat mask 40 (FIG. 3). The mask body 41 has a surface t1 of a step portion 41t in which the second through-hole 41z opens, and a U-shaped step portion 41t ′ in a plan view defined by the surfaces t2, t3, and t4 rising from the surface t1. . The sliding direction of the mask movable portion 42 is determined as one direction by the step portion 41t ′. The step portion also serving as the guide means is not limited to the U-shape in plan view, and may be appropriately selected according to the arrangement of the through holes.

  Further, in the specific example, the mask movable portion is slid in the surface direction toward the outside of the flat mask, but may be slid inward. In the case where the mask movable part is slid toward the inside of the flat mask, an accommodation space for accommodating the mask movable part after the sliding movement is required at the center of the flat mask. This accommodating space is a recess formed in the surface portion of the flat mask, and there is no adverse effect as long as it does not hinder movement of the squeegee.

  Further, in FIG. 3, the step portion 41t has an L-shaped cross section, and the surfaces t1, t2, and t3 that define the step portion 41t are flat surfaces that are orthogonal to each other. However, these planes do not necessarily have to be orthogonal. Further, in FIG. 3, the mask movable portion 42 fitted to the step portion 41 t is in contact with the surfaces t 1, t 2 and t 3 of the step portion 41. The mask movable part 42 only needs to be disposed in contact with at least the surface t1, and even if there is a gap between the surfaces t2 and t3 and the mask movable part 42 as long as the movement of the squeegee is not hindered. Good.

It is explanatory drawing which shows typically the general application | coating procedure of the solder paste by a screen printing method. It is explanatory drawing which shows typically the printing method of the solder paste using the mask for screen printing of this invention, Comprising: It is a top view of a flat mask. It is explanatory drawing which shows typically the printing method of the solder paste using the screen printing mask of this invention, Comprising: The A-A 'cross section of FIG. 2 is shown. It is a perspective view which shows typically the thin plate-shaped mask which comprises the mask for screen printing of this invention. It is explanatory drawing which shows typically the printing method of the solder paste using the mask for screen printing of this invention, Comprising: It is sectional drawing which looked at the cross section of the laminated thin mask from the front of FIG. FIG. 6 is an explanatory view schematically showing a solder paste printing method using the screen printing mask of the present invention, and shows a cross section of the flat mask after the position of the mask movable part slides from the front of FIG. 4. FIG. 5 is a cross-sectional view (III-1) and a cross-sectional view (III-2) viewed from the left side of FIG. It is explanatory drawing which shows typically the printing method of the solder paste using the mask for screen printing of this invention, Comprising: The flat mask (IV) after the mask movable part has slid all moved, and the to-be-printed object after screen printing ( It is sectional drawing which looked at the cross section of V) from the front of FIG. It is explanatory drawing which shows typically the printing method of the solder paste using the mask for screen printing of this invention, Comprising: The upper figure is a top view of a flat mask, and the lower figure is a side view of a flat mask. It is explanatory drawing which shows typically the printing method of the solder paste using the mask for screen printing of this invention, Comprising: It is a partial expanded sectional view of the through-hole vicinity of a flat mask. It is a top view which shows the modification of the flat mask shown in FIG.

Explanation of symbols

40, 50, 60, 70: flat masks 40w, 40x, 40y, 40z: through holes (40w, 40x, 40y: first through holes)
41: Mask body 41t: Stepped portion 41z: Second through hole 42: Mask movable portion 42z: Movable through hole 50w, 50x, 50y, 50z: Through hole 51: Base mask 51w, 51x, 51y, 51z: Lower through hole 52 : Partially movable mask 52 ': Fixed mask piece 52w, 52x, 52z: Lower through hole 52 ": Movable mask piece 52y: Movable through hole 53: Partially movable mask 53': Fixed mask piece 53w: Fixed through hole 53": Movable Mask pieces 53x, 53y, 53z: movable through hole S: solder paste

Claims (21)

A mask for screen printing, comprising a flat mask having a plurality of through holes penetrating in the thickness direction, and printing solder paste on the printing surface covered with the flat mask through the through holes. The mask is
A mask body in which a first through hole which is a part of the plurality of through holes and a second through hole having a length in the thickness direction shorter than the first through hole are formed,
A mask movable portion that is slidable in a surface direction on the surface of the mask body, and has a movable through hole that communicates with the second through hole and forms the remainder of the plurality of through holes;
A mask for screen printing comprising: sliding the mask movable portion to slide the solder paste filled in the second through hole and the movable through hole on an inner wall surface of the movable through hole.   The said mask main body consists of the flat base mask mounted on the said to-be-printed surface, and the flat fixed mask piece which overlaps and forms the thick part on the surface of this base mask. Mask for screen printing.   The screen printing mask according to claim 2, wherein two or more of the fixed mask pieces are superposed on the surface of the base mask in the thickness direction.   The screen printing mask according to claim 1, wherein the mask movable portion is a flat movable mask piece.   The mask for screen printing according to claim 4, wherein the movable mask part is formed by stacking two or more movable mask pieces in the thickness direction.   The screen printing mask according to claim 5, wherein the two or more movable mask pieces are individually slidable.   The screen printing mask according to claim 1, wherein the movable through hole has an inner wall surface inclined with respect to the thickness direction.   The screen printing mask according to claim 1, further comprising guide means for guiding the movement of the mask movable portion.   The screen printing mask according to claim 1, wherein the mask movable portion is made of a metal material. A flat mask having a plurality of through holes penetrating in the thickness direction, the flat mask is
A mask body in which a first through hole which is a part of the plurality of through holes and a second through hole having a length in the thickness direction shorter than the first through hole are formed,
A mask movable portion that is slidable in a surface direction on the surface of the mask body, and has a movable through hole that communicates with the second through hole and forms the remainder of the plurality of through holes;
A screen printing mask comprising:
A mask fixing means for fixing the screen printing mask to the surface of the substrate;
A solder paste filling means for filling the space defined by the surface of the substrate and the inner wall surface of the through hole with a solder paste;
With the mask main body fixed to the substrate, the mask movable part is slid to slide the solder paste filled in the second through hole and the movable through hole on the inner wall surface of the movable through hole. Solder paste scraping means;
Mask separating means for separating the substrate and the screen printing mask;
A screen printing apparatus comprising:   The said mask main body consists of the flat base mask mounted on the said to-be-printed surface, and the flat fixed mask piece which overlaps on the surface of this base mask, and forms a thick part. Screen printing equipment.   The screen printing apparatus according to claim 11, wherein two or more of the fixed mask pieces are superposed on the surface of the base mask in the thickness direction.   The screen printing apparatus according to claim 10, wherein the mask movable portion is a flat movable mask piece.   The screen printing apparatus according to claim 13, wherein the movable mask portion is formed by stacking two or more movable mask pieces in a thickness direction.   The screen printing apparatus according to claim 14, wherein the two or more movable mask pieces are individually slidable.   The screen printing apparatus according to claim 10, wherein the movable through hole has an inner wall surface inclined with respect to the thickness direction.   The screen printing apparatus according to claim 10, wherein the screen printing mask further includes guide means for guiding movement of the movable mask.   The screen printing apparatus according to claim 10, wherein the mask movable portion is made of a metal material.   The screen printing apparatus according to claim 10, wherein the solder paste filling unit includes a squeegee that moves in parallel on the screen printing mask while pressing the solder paste placed on the screen printing mask. A flat mask having a plurality of through holes penetrating in the thickness direction, the flat mask is
A mask body in which a first through hole which is a part of the plurality of through holes and a second through hole having a length in the thickness direction shorter than the first through hole are formed,
A mask movable portion that is slidable in a surface direction on the surface of the mask body, and has a movable through hole that communicates with the second through hole and forms the remainder of the plurality of through holes;
A mask fixing step of fixing a screen printing mask comprising:
A solder paste filling step of filling a space defined by the surface of the substrate and the inner wall surface of the through hole with a solder paste;
With the mask main body fixed to the substrate, the mask movable part is slid to slide the solder paste filled in the second through hole and the movable through hole on the inner wall surface of the movable through hole. Solder paste cutting process,
A mask separating step for separating the substrate and the screen printing mask;
A screen printing method comprising: A mask body in which a first through hole and a second through hole are formed, and a movable mask in which a movable through hole is formed.
The mask body has a stepped portion having a surface on which the movable mask can slide, the first through hole is formed in a portion where the mask body and the movable mask do not overlap, and the second through hole is A mask for screen printing, wherein the mask main body and the movable mask are formed in an overlapping portion, and the movable through hole is formed to be able to communicate with the second through hole at a position corresponding to the second through hole.

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