JP2012218174A - Metal mask for solder printing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metal mask for solder printing featuring that the quantity of a soldering paste to be printed on a land electrode can be made stable despite the pattern of the land electrode.SOLUTION: The metal mask for solder printing 10 includes a metal plate 12 with a pair of main surfaces opposed each other. In addition, the metal plate 12 has openings 14 passing through between the main surfaces in areas 300 to 320 respectively facing land electrodes with different areas. Besides, the areas of the openings 14, as viewed from a direction perpendicular with the main surfaces of the metal plate 12, are the same.

Description

  The present invention relates to a solder printing metal mask, and more particularly to a solder printing metal mask used for applying a solder paste to a land electrode.

  Conventionally, a metal mask is used for applying a solder paste for mounting an electronic component or the like.

  For example, the electronic component disclosed in Patent Document 1 shown in FIG. 7 has a plurality of terminal electrodes with different mounting areas for connecting to an external circuit such as a wiring board on the back surface thereof. A land electrode corresponding to the shape of the terminal electrode is formed on the wiring board or the like. A solder paste is printed on the land electrode, an electronic component is mounted thereon, and soldered by reflow or the like, thereby connecting the terminal electrode and the land electrode. Solder paste printing is performed by placing a metal mask having an opening formed in a predetermined area of a metal plate on a wiring board, etc., supplying the solder paste thereon, and moving the squeegee to remove the solder paste from the opening. Extrusion is performed by applying a solder paste to land electrodes formed at predetermined positions on the wiring board or the like and then removing the metal mask from the wiring board or the like.

JP 2004-15161 A

  The opening of the metal mask is formed corresponding to a land electrode such as a wiring board. When a large and small land electrode is mixed on a wiring board or the like, an opening having a large area corresponding to a large land electrode is formed in the metal mask, and openings having different areas are mixed.

  If a large opening is formed in the metal mask, the tip of a squeegee such as urethane rubber enters the large opening, and the phenomenon of scraping off the solder paste occurs. Therefore, the amount of solder paste printed on the land electrode may not be stable depending on the pattern of the land electrode such as the shape, size and arrangement of the land electrode such as the wiring board.

  In view of such circumstances, the present invention aims to provide a metal mask for solder printing in which the amount of solder paste printed on the land electrode is stable regardless of the pattern of the land electrode.

  In order to solve the above problems, the present invention provides a metal mask for solder printing configured as follows.

  The metal mask for solder printing includes a metal plate having a pair of main surfaces facing each other. The metal plate is a land electrode corresponding to an electronic component provided with at least two or more terminal electrodes having different mounting areas, and each land electrode is opposed to a land electrode having a different area. An opening for electronic parts penetrating between the main surfaces is formed. Each of the electronic component openings has the same area when viewed from a direction perpendicular to the main surface of the metal plate.

  In this case, since the areas of the electronic component openings formed in the land electrode facing area of the solder printing metal mask are the same, when the solder paste is printed, the tip of the squeegee enters and scrapes the solder paste. Variations in the phenomenon to be taken can be suppressed, and the amount of solder paste printed by each electronic component opening is stabilized. This stabilizes the amount of solder paste printed on the land electrode regardless of the land electrode pattern.

  In a preferred embodiment, when n is an integer of 3 or more, the opening for electronic parts is an n-gon when viewed from a direction perpendicular to the main surface of the metal plate.

  In this case, it is easy to cope with the land electrode pattern.

  More preferably, the opening for electronic parts is a square when viewed from a direction perpendicular to the main surface of the metal plate.

  In this case, the ratio (opening ratio) at which the electronic component opening is formed with respect to the land electrode facing region is increased, and when the electronic component is mounted on the land electrode, the land electrode and the terminal electrode are interposed via the solder. Since the area to be connected is increased, the connection reliability is improved.

  In another preferred aspect, the opening for electronic parts is circular when viewed from a direction perpendicular to the main surface of the metal plate.

  In this case, since there is no directionality in the opening for electronic parts, it is easy to deal with the pattern of land electrodes.

  Preferably, a plurality of the electronic component openings are formed in each of the land electrode facing regions.

  In this case, each land electrode is printed with a solder paste through a plurality of electronic component openings. The smaller the opening, the smaller the variation in the amount of solder paste to be printed, so the amount of solder paste printed on the land electrode can be made more stable.

  According to the present invention, the amount of solder paste printed on the land electrode is stabilized regardless of the pattern of the land electrode.

It is a bottom view of an electronic component. Example 1 It is a principal part top view of a wiring board. Example 1 It is a principal part top view of the metal mask for solder printing. Example 1 It is a principal part top view of the metal mask for solder printing. (Example 2) It is (a) principal part top view of a metal mask for solder printing, (b) sectional drawing, (c) It is an enlarged plane. (Comparative example) It is a principal part top view of the metal mask for solder printing. (Other configurations) It is a terminal electrode arrangement | positioning figure of the bottom part of an electronic component.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  <Example 1> The metal mask 10 for solder printing of Example 1 is demonstrated, referring FIGS. 1-3.

  FIG. 1 is a bottom view of the electronic component 2. FIG. 2 is a plan view of a main part of the wiring board 4. FIG. 3 is a plan view of a principal part of the metal mask 10 for solder printing.

  The solder mask metal mask 10 shown in FIG. 3 has solder particles for connecting the terminal electrodes 100 to 120 of the electronic component 2 shown in FIG. 1 to the land electrodes 200 to 220 of the wiring board 4 shown in FIG. It is used when applying a solder paste that is kneaded with a flux to form a paste.

  As shown in FIG. 1, a terminal electrode 100 having a relatively large area is formed on the bottom surface 2a of the electronic component 2 at the center of the rectangular bottom surface 2a, and relative to each other along each side of the bottom surface 2a. Terminal electrodes 101 to 120 having a small area are formed. The electronic component 2 is, for example, a QFN (quad flat non-leaded package), and the central terminal electrode 100 has a large area for the purpose of heat dissipation.

  Corresponding to the terminal electrodes 100 to 120 of the electronic component 2, land electrodes 200 to 220 are formed on the main surface 4 a of the wiring board 4 as shown in FIG. 2. That is, a substantially square land electrode 200 having a relatively large area corresponding to the terminal electrode 100 of the electronic component 2 is formed on the main surface 4a of the wiring board 4, and the terminal electrodes 101 to 101 of the electronic component 2 are formed around the land electrode 200. Corresponding to 120, rectangular land electrodes 201 to 220 having a relatively small area are formed.

  As shown in FIG. 3, the solder printing metal mask 10 includes a metal plate 12 having a pair of opposed main surfaces. The metal plate 12 is formed of metal on land electrode facing regions 300 to 320 facing the land electrodes 200 to 220 of the wiring board 4 when the solder printing metal mask 10 is disposed on the main surface 4a of the wiring board 4, respectively. An opening 14 penetrating between the main surfaces of the plate 12 is formed. The opening 14 is an opening for the electronic component 2 (electronic component opening).

  Specifically, 7 × 7 openings 14 are formed in the land electrode facing region 300 having a relatively large area facing the land electrode pair 200 having a relatively large area. In the land electrode facing regions 301 to 320 having relatively small areas facing the land electrodes 201 to 220 having relatively small areas, two openings 14 are respectively formed.

  The solder printing metal mask 10 is placed on the main surface 4 a of the wiring board 4, a solder paste (not shown) is supplied thereon, and the squeegee is pressed against the solder printing metal mask 10 in the direction indicated by the arrow 50. The solder paste is applied to the land electrodes 200 to 220 of the wiring board 4 by moving and extruding the solder paste from the opening 14, and then removed from the wiring board 4.

  All the openings 14 formed in the land electrode facing regions 300 to 320 of the solder printing metal mask 10 are perpendicular to the main surface of the metal plate 12 of the solder printing metal mask 10 (perpendicular to the paper surface in FIG. 3). When viewed from, the squares have the same dimensions, and the areas of all the openings 14 are the same. The area of the opening 14 causes a phenomenon that the tip of the squeegee enters and scrapes off the solder paste when printing the solder paste onto the land electrodes 200 to 220 of the wiring board 4 using the metal mask 10 for solder printing. The size should be able to suppress this. This stabilizes the amount of solder paste printed by each opening 14.

  For example, by using a metal mask 10 for solder printing in which a square opening 14 of 0.33 × 0.33 mm is formed on a metal plate 12 having a thickness of 0.12 mm, the solder particle diameter is 10 to 25 μm, and the viscosity is 180 to A commercially available solder paste of 220 Pa · s could be stably supplied onto the land electrodes 200 to 220.

  Since the shape of the opening 14 is a square and has sides that are orthogonal to each other, it easily corresponds to the pattern of the land electrodes 200 to 220. In addition, the reliability of connection between the land electrode and the terminal electrode is improved.

  That is, when the opening of the metal plate of the solder printing metal mask is made square, the opening has an orthogonal side, so that it can be easily formed corresponding to the land electrode pattern. This is because the terminal electrodes of the electronic component are usually arranged so as to be orthogonal to each other, and the land electrodes are arranged so as to be orthogonal to each other. It is also easy to arrange all the openings in the same direction.

  Further, when the opening 14 is square, the ratio of the opening to the land electrode facing region (opening ratio) is increased, and when the electronic component is mounted on the land electrode, the land electrode and the terminal electrode are Since the area connected via the solder increases, the connection reliability is improved.

  In the solder printing metal mask 10, a plurality of openings 14 are formed for all the land electrode facing regions 300 to 320, respectively. Therefore, any of the land electrodes 200 to 220 has a solder paste formed by the plurality of openings 14. Printed. The smaller the opening 14, the smaller the variation in the amount of solder paste printed by the opening 14, so printing is performed on the land electrode than when only one opening is formed in each land electrode facing region. The amount of solder paste applied can be stabilized.

  However, it is also possible to form only one opening in each of the land electrode facing regions 301 to 320 having a relatively small area.

  <Example 2> The metal mask 10a for solder printing of Example 2 is demonstrated referring FIG.

  FIG. 4 is a plan view of an essential part of the solder printing metal mask 10a. As shown in FIG. 4, the solder printing metal mask 10a of Example 2 is different from that of Example 1 only in that the shape of the opening 14a having the same area formed in each of the land electrode facing regions 300 to 320 is circular. It is different from the metal mask 10 for solder printing.

  In the solder mask metal mask 10a of the second embodiment, since the areas of all the openings 14a are the same, the amount of solder paste printed on the land electrodes 200 to 220 can be stabilized.

  For example, using a solder printing metal mask 10a in which a circular opening 14a having a diameter of 0.37 mm is formed on a metal plate 12 having a thickness of 0.12 mm, the solder particle diameter is 10 to 25 μm, and the viscosity is 180 to 220 Pa · s. Can be stably supplied onto the land electrode.

  Furthermore, since the circular opening 14a has no directionality, it can easily correspond to a land electrode pattern. Further, the amount of solder paste printed by each opening is the same no matter which direction the squeegee is moved.

  Comparative Example A solder printing metal mask 10x of a comparative example will be described with reference to FIG.

  Fig.5 (a) is a principal part top view of the metal mask 10x for solder printing. FIG.5 (b) is sectional drawing cut | disconnected along line AA of Fig.5 (a). FIG. 5C is an enlarged plane of the solder printing metal mask 10x.

  The solder printing metal mask 10x of the comparative example is formed with substantially square openings 400a to 400d divided into four corresponding to the central land electrode 200 of the wiring board 4 shown in FIG. Rectangular openings 401 to 420 corresponding to the electrodes 201 to 220 are formed.

  As shown in the sectional view of FIG. 5B, a solder printing metal mask 10x is arranged on the wiring board 4 on which the resist 8 is formed between the land electrodes 200 to 220, and the squeegee is shown in FIG. When moved in the direction indicated by the arrow 50, urethane rubber or the like is formed in the openings 400a to 400d, 401 to 405, 411 to 415 having large dimensions in the direction perpendicular to the moving direction of the squeegee as shown in FIG. The phenomenon that the tip of the squeegee enters and scrapes off the solder paste 6 occurs.

  Therefore, the amount of solder paste to be printed may not be stable depending on the land electrode pattern such as the shape, size, and arrangement of land electrodes such as a wiring board.

  On the other hand, since the openings 14 and 14a of the solder printing metal masks 10 and 10a of Examples 1 and 2 have the same area, all the openings 14 and 14a are perpendicular to the moving direction of the squeegee. By reducing the size, it is possible to suppress the phenomenon that the tip of the squeegee enters the opening and scrapes off the solder paste.

  <Summary> As described above, by making all the openings formed in the land facing region facing the land electrode the same area on the solder printing metal mask, the solder paste printed by each opening The amount is stable. Therefore, the amount of solder paste printed on the land electrode is stabilized regardless of the land electrode pattern.

  The present invention is not limited to the above embodiment, and can be implemented with various modifications.

  FIG. 6 is a plan view of an essential part of a solder printing metal mask 10b in another configuration of the present invention. As shown in FIG. 6, the solder printing metal mask 10 b is the same as the solder printing metal mask of Example 1 except that the opening 14 and the opening 14 b having the same area and different shapes are formed in the land electrode facing region 300. Different from the mask 10. In this solder printing metal mask 10b, the areas of all the openings 14 and the openings 14b are the same, so that the amount of solder paste printed on the land electrodes 200 to 220 can be stabilized.

  For example, the metal mask for solder printing of the present invention may be used for applying a conductor paste other than the solder paste on the land electrode.

2 Electronic component 4 Wiring board 10, 10a, 10b, 10x Solder printing metal mask 12 Metal plate 14, 14a, 14b Opening 100-120 Terminal electrode 200-220 Land electrode 300-320 Land electrode facing area 400a-400d Opening 401-420 opening

Claims (5)

A metal plate having a pair of main surfaces facing each other;
The metal plate is a land electrode corresponding to an electronic component having at least two or more terminal electrodes having different areas to be mounted, and each land electrode facing region is opposed to each land electrode having a different area. , An opening for electronic parts penetrating between the main surfaces is formed,
Each of the opening parts for electronic parts has the same area when viewed from a direction perpendicular to the main surface of the metal plate. When n is an integer of 3 or more,
2. The solder mask metal mask according to claim 1, wherein the opening for an electronic component is an n-gon when viewed from a direction perpendicular to the main surface of the metal plate.   3. The metal mask for solder printing according to claim 2, wherein the opening for electronic parts is square when viewed from a direction perpendicular to the main surface of the metal plate.   The metal mask for solder printing according to claim 1, wherein the opening for electronic parts is circular when viewed from a direction perpendicular to the main surface of the metal plate.   The metal mask for solder printing according to any one of claims 1 to 4, wherein a plurality of openings for the electronic component are formed in each of the land electrode facing regions.

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