JP2012086531A - Mask for printing solder paste, method of manufacturing the same, and device for printing solder paste - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the blotting of electrodes and a bridge by preventing solder paste from entering a gap between a substrate and a mask even if using the solder paste for a fine pitch, and to highly precisely print the solder paste on the substrate.SOLUTION: A photosensitive resist mask formed on the surface of a metal layer 21 is exposed, an opening for etching an arbitrary shape is formed at the resist mask, and the metal layer 21 is etched through the opening for etching the resist mask to form an opening at the metal layer 21, thus manufacturing the mask 20 for printing a solder paste. The mask 20 for printing the solder paste has the opening 20a of an arbitrary shape through which the solder paste is made to pass, and is provided with the resist mask in a layered state on the metal layer 21 as an etching resist layer 22.

Description

  The present invention relates to a solder paste printing mask suitable for fine pitch printing, a manufacturing method thereof, and a solder paste printing apparatus.

  In recent years, with the miniaturization of electronic components, there is a demand for a reduction in size of joint electrodes (bumps) of a substrate on which the electronic components are mounted. The bumps can be formed by melting the solder paste printed on the substrate. However, if the solder paste particle size is too large for the printing area, the bumps formed by the variation in printing amount There is a risk that variations in the length and problems such as poor bonding may occur.

For this reason, refinement | miniaturization of solder powder and the pasting technique of fine powder are advanced. For example, a fine pitch solder paste using a solder powder having a volume cumulative median diameter (Median diameter: D ₅₀ ) of 5 μm or less has been developed.

  Screen printing is generally used as a technique for printing a solder paste on a substrate or the like. For example, in the screen printing machine disclosed in Patent Document 1, a squeegee is placed along the upper surface of the mask with the mask brought into contact with the upper surface of the substrate sucked and held on the printing table (stage) and the solder paste placed on the mask. The solder paste is printed on the substrate surface through the opening formed in the mask.

  In this apparatus, a mask surface holding member for holding the peripheral portion of the mask is provided at the peripheral portion of the substrate, and the mask is vacuum-adsorbed on the mask surface holding member, or the mask is formed of a magnetic metal and the mask surface. By providing an electromagnet at the mask contact portion of the holding member, the mask is brought into close contact with the mask surface holding member, thereby preventing displacement of the mask with respect to the substrate.

JP 2009-143110 A

  By the above-described mask holding method, it is possible to prevent the positional deviation between the substrate and the mask in the surface direction. However, when a fine-pitch solder paste is used, even if there is a gap of several μm between the substrate and the mask, the solder paste penetrates into this gap, and the electrodes are formed by blurring or adjacent bumps. There is a risk that a bridge connecting the two may be formed.

  The present invention has been made in view of such circumstances, and even when a fine-pitch solder paste is used, the solder paste is prevented from entering between the substrate and the mask to prevent bleeding of the electrodes and bridges. The object is to reduce generation and to print solder paste on a substrate with high accuracy.

  The present invention is a solder paste printing mask comprising a metal layer and an etching resist layer laminated on the surface of the metal layer, and comprising an arbitrary opening that penetrates the metal layer and the etching resist layer.

  According to this solder paste printing mask, since the etching resist layer that is in close contact with the substrate is provided, a gap is hardly formed between the upper surface of the substrate and the lower surface of the mask. Therefore, even when a fine-pitch solder paste is used for screen printing, the solder paste hardly enters between the mask lower surface and the substrate upper surface from the opening, and high-precision printing is possible.

  In this solder paste printing mask, the thickness of the etching resist layer is preferably set to 1 to 5 μm. This is because if the etching resist layer is too thin, the effect of adhering to the substrate may not be sufficiently obtained or may be damaged, and if it is too thick, it may be greatly deformed and printing accuracy may be reduced.

  The present invention also includes a step of laminating and forming a photosensitive resist mask on the surface of the metal layer, an exposure mask having an opening for exposure disposed on the resist mask, and exposing the resist mask through the opening for exposure. Forming an etching opening in the resist mask, etching the metal layer through the etching opening in the resist mask, and forming an opening having a shape corresponding to the etching opening in the metal layer. The resist mask is formed on the metal layer as an adhesion layer for the printed material and is not removed while being produced.

  According to this manufacturing method, it is possible to easily manufacture a solder paste printing mask that easily adheres to the substrate and prevents the fine pitch solder paste from entering the substrate.

  In this method for manufacturing a solder paste printing mask, the resist mask is preferably formed to a thickness of 1 to 5 μm. This is because if the resist mask is too thin, the effect of being in close contact with the substrate may not be sufficiently obtained or may be damaged. If the resist mask is too thick, the resist mask may be greatly deformed to reduce the printing accuracy.

  The present invention also includes a stage for holding a substrate to be printed, an etching resist layer and a metal layer, and has an opening through which a solder paste can pass. A solder paste printing mask disposed so as to closely contact the etching resist layer; and a squeegee that moves along the upper surface of the solder paste printing mask and passes the solder paste through the opening and adheres to the substrate. An apparatus for printing solder paste comprising:

  According to this solder paste printing apparatus, the etching resist layer of the solder paste printing mask is brought into close contact with the substrate and screen printing is performed, so even a fine pitch solder paste does not easily enter between the mask and the substrate. High-precision printing is possible.

  In this solder paste printing apparatus, the thickness of the etching resist layer is preferably 1 to 5 μm. This is because if the etching resist layer is too thin, the effect of adhering to the substrate may not be sufficiently obtained or may be damaged, and if it is too thick, it may be greatly deformed and printing accuracy may be reduced.

  According to the present invention, even when a fine-pitch solder paste is used, it is possible to prevent the solder paste from entering between the substrate and the mask. Can be printed on the substrate with accuracy.

It is sectional drawing which shows the apparatus for solder paste printing provided with the mask for solder paste printing which concerns on one Embodiment of this invention. It is sectional drawing which shows the process of laminating | stacking and forming the photosensitive resist mask on the surface of a metal layer in the manufacturing method of the mask for solder paste printing concerning this invention. In the method of manufacturing a solder paste printing mask according to the present invention, an exposure mask having an arbitrary exposure opening is disposed on the resist mask, and the resist mask is exposed through the exposure opening to correspond to the exposure opening. It is sectional drawing which shows the process of forming the opening part for an etching in a resist mask. In the manufacturing method of the solder paste printing mask according to the present invention, it is a cross-sectional view showing a state in which an opening for etching is formed in the resist mask. In the method of manufacturing a solder paste printing mask according to the present invention, the metal layer is etched through the opening for etching the resist mask so that an opening having a shape corresponding to the opening for etching is formed in the metal layer. It is sectional drawing shown. It is sectional drawing which shows the printing method using the apparatus for solder paste printing shown in FIG. It is sectional drawing which shows the state by which the solder paste was printed on the board | substrate using the apparatus for solder paste printing shown in FIG.

  Hereinafter, embodiments of the present invention will be described. As shown in FIG. 1, a solder paste printing apparatus 10 according to the present invention includes a stage 11 that holds a substrate 100 that is a substrate to be printed, and a solder paste printing mask that has an opening 20a having an arbitrary shape that allows the solder paste P to pass therethrough. (Hereinafter referred to as “mask”) 20, a squeegee 13 that moves along the upper surface of the mask 20 and adheres the solder paste P to the substrate 100 through the opening 20 a, and a frame 14 that holds the mask 20.

  The substrate 100 is made of, for example, glass, epoxy resin or the like, and is formed in a rectangular planar shape having a thickness of 1.5 to 3 mm and a size of about 20 cm × 20 cm to about 40 cm × 40 cm. The substrate 100 has land portions 101 formed on the upper surface, and positioning marks (not shown) for aligning the mask 20 at four corners.

  The stage 11 is a printing table on which the substrate 100 is placed when the solder paste P is printed. The solder paste printing apparatus 10 includes a moving device (not shown) that relatively moves the stage 11 and the mask 20.

  The mask 20 is formed by laminating a metal layer 21 and an etching resist layer (hereinafter “resist layer”) 22 having a thickness of 1 to 5 μm so that the resist layer 22 is brought into close contact with the substrate 100 on the stage 11 during printing. Placed in. The metal layer 21 is made of, for example, stainless steel, and the resist layer 22 is made of a resin material (for example, polyester) having adhesiveness to the substrate 100. When screen printing is performed using the mask 20, the thickness of the solder paste P to be printed (that is, the size of the bump) is determined according to the thickness of the metal layer 21.

  The opening 20 a of the mask 20 has substantially the same shape as the land 101 of the substrate 100 and is provided at a location corresponding to the land 101. These openings 20a are set to have a pitch of 120 μm or less (for example, 80 to 120 μm) and a diameter of about 60 to 90 μm. The mask 20 is provided with a positioning mark (not shown) for the substrate 100.

  The frame body 14 is provided so as to hold the peripheral edge portion of the mask 20 and be movable up and down with respect to the stage 11.

  The solder paste printing mask 20 includes a step of laminating and forming a photosensitive resist mask 23 on the surface of the metal layer 21, and an exposure mask 24 having an optional exposure opening 24 a disposed on the resist mask 23. The resist mask 23 is exposed to light through the opening 24a, and an etching opening 23a having a shape corresponding to the exposure opening 24a is formed in the resist mask 23, and the metal layer 21 is formed through the etching opening 23a of the resist mask 23. And the step of forming in the metal layer 21 an opening 21a having a shape corresponding to the etching opening 23a. In the present invention, the resist mask 23 is not removed from the mask 20 even after the metal layer 21 is etched, and is used for screen printing while being provided as the resist layer 22 in close contact with the substrate 100.

  More specifically, first, as shown in FIG. 2, a photosensitive resist mask 23 is laminated on the surface of the metal layer 21. Note that the resist mask 23 can be formed using either a negative photoresist in which an exposed portion remains after development or a positive photoresist from which the exposed portion is removed after development, but here, a positive photoresist is used. The case of forming will be described.

  As an example of a positive photoresist, for example, a bis (aminophenol) compound, a polybenzoxazole precursor resin (base resin) having a structure derived from a dicarboxylic acid, and a diazoquinone compound (photosensitive agent), an alkaline aqueous solution And a positive photosensitive resin composition that can be developed by the above method. As an example of a negative photoresist, for example, a polybenzoxazole precursor is compounded with a compound that generates an acid upon irradiation with radiation and a compound that can crosslink the polybenzoxazole precursor by the action of this acid. And heat-resistant negative photosensitive resin compositions.

  Next, as shown in FIG. 3, an exposure mask 24 having an arbitrary exposure opening 24a is placed on the resist mask 23, irradiated with light as indicated by an arrow in the figure, and the resist mask passes through the exposure opening 24a. 23 is exposed. Then, as shown in FIG. 4, the exposure mask 24 is removed, and the resist mask 23 is developed to remove a portion (exposed portion) corresponding to the exposure opening 24a, and the etching opening 23a is removed from the resist mask 23. To form. In addition, an insoluble film 25 is attached to the back surface of the metal layer 21. As an insoluble film, for example, a masking tape made of PET resin, acrylic resin, vinyl or the like coated with a pressure-sensitive adhesive having water repellency on one side (for example, photomask protection manufactured by Sekisui Chemical Co., Ltd.) Tape “Tuckwell (trade name)” or the like can be used.

Next, as shown in FIG. 5, the metal layer 21 is etched through the etching opening 23a by using an etching solution such as FeCl ₂ solution, and the opening 21a having the same shape as the etching opening 23a is formed into the metal layer 21. To form. Thereby, the opening 21a and the etching opening 23a communicate with each other, and the printing opening 20a penetrating the metal layer 21 and the resist mask 23 in the thickness direction is formed. The insoluble film 25 is not dissolved by the etching solution, holds the metal layer 21, and prevents the metal layer 21 from being etched from the back surface.

  Then, by removing the insoluble film 25, the metal layer 21 and a resist mask 23 (that is, a resist layer 22) having a thickness of 1 to 5 μm laminated on the surface of the metal layer 21 are provided. A solder paste printing mask 20 having an opening 20 a penetrating 22 is manufactured. That is, the resist mask 23 is not removed even after the metal layer 21 is etched, and the mask 20 is configured as an adhesion layer having adhesiveness to the substrate 100.

  When printing on the substrate 100 using the solder paste printing apparatus including the solder paste printing mask 20 manufactured as described above, the mask 20 is placed so that the resist layer 22 contacts the substrate 100 as shown in FIG. Place. At this time, the mask 20 and the substrate 100 are positioned using the above-described positioning marks so that the opening 20 a of the mask 20 matches the land portion 101 of the substrate 100.

  In this state, the solder paste P is attached to the land portion 101 of the substrate 100 through the opening 20a by moving the squeegee 13 along the upper surface of the mask 20 as indicated by an arrow in the figure. At this time, since the resist layer 22 having adhesiveness with respect to the substrate 100 is in close contact with the substrate 100 without any gap, even the solder paste P formed by pasting fine powder into the substrate 100 from the opening 20a. As shown in FIG. 7, it is printed on the substrate 100 with high accuracy.

  As described above, according to the printing apparatus 10 including the mask 20 according to the present invention, even the fine-pitch solder paste P can be accurately printed on the substrate 100 without blurring. Therefore, even when the solder paste P is melted and the bumps are formed on the substrate 100, it is difficult to form a bridge between the bumps, and it is possible to manufacture a substrate on which the minimum bumps are precisely arranged.

  In addition, this invention is not limited to the thing of the structure of the said embodiment, In a detailed structure, it is possible to add a various change in the range which does not deviate from the meaning of this invention.

DESCRIPTION OF SYMBOLS 10 Solder paste printing apparatus 11 Stage 13 Squeegee 14 Frame 20 Solder paste printing mask 20a Opening 21 Metal layer 21a Opening 22 Etching resist layer 23 Resist mask 23a Etching opening 24 Exposure mask 24a Exposure opening 25 Insoluble Film 100 substrate (substrate)
101 Land P Solder paste

Claims (6)

A solder paste printing mask having an opening of an arbitrary shape allowing the solder paste to pass therethrough,
A mask for solder paste printing, comprising: a metal layer; and an etching resist layer laminated on a surface of the metal layer, and the opening passing through the metal layer and the etching resist layer.   The solder paste printing mask according to claim 1, wherein the etching resist layer has a thickness of 1 to 5 μm. A step of laminating a photosensitive resist mask on the surface of the metal layer;
Arranging an exposure mask having an exposure opening on the resist mask, exposing the resist mask through the exposure opening, and forming an etching opening in the resist mask; and
Etching the metal layer through the etching opening of the resist mask, and forming an opening having a shape corresponding to the etching opening in the metal layer,
The method of manufacturing a mask for solder paste printing, wherein the resist mask is not removed as it is formed on the metal layer as an adhesion layer for a substrate which is a substrate to be printed.   The method of manufacturing a solder paste printing mask according to claim 3, wherein the resist mask is formed to a thickness of 1 to 5 μm. A stage for holding a substrate which is a substrate to be printed;
Solder paste comprising a metal layer and an etching resist layer laminated, having an opening of an arbitrary shape through which the solder paste passes, and disposed so that the etching resist layer is in close contact with the substrate on the stage A mask for printing;
A solder paste printing apparatus, comprising: a squeegee that moves along an upper surface of the solder paste printing mask and adheres the solder paste to the substrate through the opening.   6. The apparatus for printing solder paste according to claim 5, wherein the etching resist layer has a thickness of 1 to 5 [mu] m.

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