JP6171161B1 - Method for manufacturing a mask for solder printing - Google Patents

Abstract

Provided is a solder printing mask that has excellent followability to a step of a substrate and can adhere well to the substrate so that printing can be performed without blurring. A thermosetting adhesive sheet or a resin layer made of a laminate of a polyimide sheet and a thermosetting adhesive sheet is laminated with a flat metal plate such as stainless steel or nickel, and the thermosetting adhesive sheet is subjected to the thermosetting conditions. After curing, an opening is formed in a predetermined size and pattern by an ultraviolet laser. Alternatively, nickel plating is directly formed on the resin layer, and an opening is formed by ultraviolet laser processing. [Selection] Figure 1

Description

  The present invention relates to a mask used for solder printing and a manufacturing method thereof in the field of mounting electronic components.

  In mounting electronic parts, in order to print a solder paste on a part on which a board part is to be mounted, a metal mask in which an opening corresponding to a printing pattern is formed on a thin metal plate is widely used (for example, , See Patent Document 1).

  At the time of solder paste printing, this metal mask is installed in a printing machine, and an appropriate amount of paste is placed on the surface facing the board (printing surface) and the opposite surface (squeegee surface), and the squeegee is pressured on the squeegee surface. The solder paste is extruded from the opening and printed on the substrate.

  Here, the surface of the substrate is not always flat and often has a step due to the formation of the wiring pattern, land, and solder resist. In particular, in recent years, with the spread of portable terminals, the substrate is also mounted on a thin and deformable flexible substrate using polyimide instead of a rigid and non-rigid rigid substrate using a glass epoxy resin plate. However, the flexible substrate is a substrate having a larger number of irregularities than the rigid substrate.

  In such a case, a metal mask composed only of a metal plate cannot be deformed according to the level difference of the substrate due to the hardness of the metal, and the printing surface of the metal mask does not adhere to the substrate, so printing defects such as bleeding are not possible. It was the cause.

  In order to cope with this problem, a solder printing mask 100, which is a composite structure of plastic and metal having flexibility, is used instead of the metal mask (see, for example, Patent Documents 2 and 3). .

  FIG. 11 is a schematic side view of a conventional solder printing mask 100. The solder printing mask 100 has a laminated structure in which a printing surface includes a plastic sheet 101, a first metal layer 102, a second metal layer 103, and an opening. The plastic sheet 101 has a printing surface, and the second metal layer 103 has a printing surface. Used as a squeegee surface.

  Here, the solder printing mask 100 is formed by forming the metal layer 102 on the plastic sheet 101 by electro nickel plating on the first metal layer 103 made of copper thin film formed by sputtering or electroless copper plating. An opening is formed by processing or etching.

  That is, in order to manufacture the conventional solder printing mask 100, a sputtering device or an electroless copper plating facility for forming a copper thin film on the plastic sheet 101 is prepared, or a commercially available copper / plastic laminated sheet. Had to be used. However, the former is problematic in that the capital investment increases and the manufacturing process becomes complicated. On the other hand, in the latter case, since a commercially available copper / plastic laminated sheet is more expensive than a single plastic sheet, there is a problem of an increase in cost. Furthermore, when the types of thicknesses available for the convenience of the manufacturer are limited, the first metal layer 102 and the second metal layer 103 with respect to the total thickness of the solder printing mask 100 (the total thickness of each layer). There was a problem that the total thickness could not be controlled.

  The conventional solder printing mask 100 of FIG. 11 uses a commercially available copper / plastic laminated sheet, and the total thickness of the first metal layer 102 and the second metal layer 103 is thicker than that of the plastic sheet 101. It has become.

  FIG. 12 shows a use state of a conventional solder printing mask 100. When the solder paste P is printed by sliding the metal mask squeegee surface (second metal layer 103) while applying pressure when the substrate 201 has a level difference, the conventional solder printing mask 100 has a total thickness. Since the metal ratio is high and the rigidity is high, even the pressure of the squeegee 202 does not follow the step and does not adhere to the substrate. For this reason, the solder paste P is not properly transferred onto the substrate 201, which causes defects such as bleeding and insufficient printing.

JP2009-113384A JP-A-10-138657 JP 2000-334909 A

  In view of the above circumstances, an object of the present invention is to provide a solder printing mask that has high followability to a step of a substrate during printing, adheres well to the substrate, has good print quality, and a simple manufacturing method thereof. It is.

In order to achieve the above-mentioned object, the invention according to claim 1 is characterized in that a resin layer in which an epoxy thermosetting adhesive sheet having a thickness of 0.02 to 0.06 mm is laminated to a desired thickness is provided in a predetermined manner. A step of curing under curing conditions, a step of forming a base made of a nickel plating film of 0.5 to 1.5 μm by electroless nickel plating on the resin layer, and a total thickness by electro nickel plating on the base A step of forming a metal layer by forming a metal layer by nickel plating with a thickness of 1/3 or less and 0.015 mm or more from the resin layer side of the metal / resin laminate And a step of processing the metal / resin laminate to form an opening with a predetermined pattern by irradiating with an ultraviolet laser.

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According to the first aspect of the present invention, the thickness of the resin layer is freely set as compared with the conventional one, and the total thickness of the solder printing mask is kept constant, while the thickness of the metal layer is made larger than the thickness of the resin layer. By reducing the thickness, it is possible to manufacture a solder printing mask having a good print quality with high followability to the step of the substrate of the solder printing mask during printing by a simple method.

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It is the front view (a) of the outline of the mask for solder printing based on Embodiment 1 of this invention, and a side view (b). It is a general | schematic process flowchart which shows the manufacturing method of the mask for solder printing based on Embodiment 1 of this invention. It is a schematic side view showing the use condition of the mask for solder printing based on Embodiment 1 of this invention. It is a schematic process flowchart which shows the manufacturing method of the mask for solder printing based on Embodiment 2 of this invention. It is the front view (a) of the outline of the mask for solder printing based on Embodiment 3 of this invention, and a side view (b). It is a schematic process flowchart which shows the manufacturing method of the mask for solder printing based on Embodiment 3 of this invention. It is a general | schematic process flowchart which shows the manufacturing method of the mask for solder printing based on Embodiment 4 of this invention. It is the front view (a) of the outline of the mask for solder printing based on Embodiment 5 of this invention, and a side view (b). It is a general | schematic process flowchart which shows the manufacturing method of the mask for solder printing based on Embodiment 5 of this invention. It is a general | schematic process flowchart which shows the manufacturing method of the mask for solder printing based on Embodiment 6 of this invention. It is a schematic side view of the conventional solder printing mask. It is a schematic side view showing the use condition of the conventional solder printing mask.

  Embodiments of the present invention will be described with reference to the accompanying drawings. In the drawings, the size, interval, number, and other details of the configuration of each part in the drawings are expressed greatly simplified and omitted from actual ones for the sake of visual recognition and understanding.

Embodiment 1
FIG. 1 is a schematic front view (a) and side view (b) of a solder printing mask 1 according to the first embodiment.

  The solder printing mask 1 includes a flat metal plate (metal layer) 13, a thermosetting adhesive sheet (adhesive layer) 12 coated on the entire surface of one side of the metal plate 13, and a thermosetting adhesive sheet 12. It has a flat laminated structure composed of a polyimide sheet 11 fixed on the opposite side of the metal plate 13, and the arrangement, number, size, and shape (hereinafter referred to as "array") corresponding to the printed pattern in the surface. It is comprised from the opening 14 formed in this. Here, in this Embodiment 1, the lamination | stacking which consists of the thermosetting type adhesive sheet 12 and the polyimide sheet 11 is called resin layer. The same applies to the following embodiments.

  In the first embodiment, a nickel plate formed by electric nickel plating is used as the material of the metal plate 13. The size of the plate is a square having a side of 300 to 600 mm, the plate thickness is 0.015 mm or more, and the thickness of the resin layer (that is, the thickness of the thermosetting adhesive sheet 12 and the polyimide sheet 11). Total) is set to be thinner.

  The thermosetting adhesive sheet 12 is a thermosetting adhesive sheet made of an epoxy resin having excellent chemical resistance, and is cured by heat or pressure to exert an adhesive force. The thickness of the thermosetting adhesive sheet 12 is basically 0.02 to 0.06 mm, but is not limited to the existing thickness, and can be used by being overlapped and thickened. .

  The polyimide sheet 11 is a film having a thickness of 0.025 to 0.125 mm, and the outer dimension is set to be equal to or larger than the area capable of covering all the openings 14 of the metal plate 13 and smaller than the outer dimension of the metal plate 13. . Since the material polyimide is excellent in chemical resistance and heat resistance and has high mechanical strength, it is suitable as a material for the printing surface of the solder printing mask 1.

  Here, the thickness of the metal plate 13 with respect to the total thickness is less than 1/2, preferably 1/3 or less. However, it is 0.015 mm or more as described above. If it is less than 0.015 mm, the strength of the solder printing mask 1 is insufficient, and it tends to cause elongation or breakage during printing, and if it is 1/2 or more, the rigidity becomes high and the board followability decreases. The print quality will be lowered.

  The opening 14 is a hole formed in the solder printing mask 1 and integrally penetrates the metal plate 13 and the resin layer. Further, it is formed in an array corresponding to the print pattern. Here, the arrangement and the like of the openings 14 differ depending on the products to be produced using the solder printing mask 1. For example, the opening 14 generally has a side or a diameter of 0.1 mm or more. The interval is set to 0.1 mm or more. In addition, when processing with an ultraviolet laser described later, as shown in FIG. 1B, the area of the opening 14 on the polyimide sheet 11 side is larger than that on the metal plate 13 side. By adopting such a shape, during solder printing, the inner wall of the opening 14 takes a form of a forward taper in which the hole expands from the squeegee side toward the workpiece side. Therefore, from the solder opening 14 after solder printing, This is better than when the taper is not forward tapered (when there is no taper or when there is a reverse taper).

  Next, a method for manufacturing the solder printing mask 1 according to the first embodiment will be described based on a schematic process flow diagram showing the method for manufacturing the solder printing mask 1 shown in FIG.

  First, the metal plate 13 is prepared by electroforming (step S1). Electro nickel plating, which is a method of forming the metal plate 13 in the first embodiment, immerses a plating base made of stainless steel in a plating bath containing nickel sulfamate or nickel sulfate as a metal salt, and Electric nickel plating is performed on the plating base material by energizing between them. Here, the plating substrate is larger than the metal plate 13 to be produced. After energization to a predetermined thickness (corresponding to the thickness of the metal plate 13), the electroplating is stopped, the plating substrate is lifted from the plating bath, and the nickel film as the plating product is peeled off from the plating substrate. Thus, the metal plate 13 is produced. At this time, the plating film formed on the peripheral portion of the plating base material is lost at the time of peeling. Therefore, as described above, the plating base material is made larger than the metal plate 13 to be created by the loss.

  The thermosetting adhesive sheet 12 processed to the same size and the polyimide sheet 11 are overlapped on the metal plate 13 in this order to form a metal / resin laminate, and pressed at 70 to 100 ° C. for 1 to 10 seconds. The metal plate 13 and the polyimide sheet 11 are pressure-bonded and temporarily bonded by the adhesive force generated in the thermosetting adhesive sheet 12 softened by heat (step S2). In this crimping step, the polyimide sheet 11 and the metal plate 13 are temporarily bonded, and by performing temporary bonding appropriately, sufficient adhesive strength can be obtained when thermosetting is performed in the next step. On the other hand, if the temperature and time are not appropriate, sufficient adhesive strength cannot be obtained after thermosetting, causing problems.

  Next, the metal / resin laminate is thermally cured. Thermosetting is performed in a furnace of a heat dryer set to a predetermined temperature, and heat is applied for a predetermined curing time or more to thermally cure the thermosetting adhesive sheet, thereby fixing the metal plate 13 and the resin layer. (Step S3). Here, the temperature of the heat dryer varies depending on the curing conditions of the thermosetting adhesive sheet, and is set in a range of 100 to 150 ° C. in the first embodiment. The curing time is 1 hour or longer, more preferably 2 hours or longer.

  Next, a laser is irradiated from the resin layer side of the metal / resin laminate to form openings with a predetermined pattern (step S4). Here, as a light source of the laser processing method, an ultraviolet laser that can cleanly cut a flame-retardant resin such as polyimide without breaking the shape of the cut portion is used.

  In this way, the produced solder printing mask 1 is placed on an aluminum frame and a screen frame made of a polyester screen fixed to the aluminum frame with a constant tension so that the polyimide sheet 11 becomes a printing surface. By stretching and making the plate (the polyimide sheet 11 faces the opposite side of the frame across the screen), it can be set in a printing machine, and is used for solder printing.

  Next, a solder printing method using the solder printing mask 1 as an operation of the invention according to the first embodiment will be described with reference to FIG.

  The printing plate on which the solder printing mask 1 is stretched and the substrate 201 with a step are set on a printing machine so that the polyimide sheet 11 is the printing surface and this is opposed to the substrate 201.

  An appropriate amount of solder paste P is placed on the metal plate 13 that is the squeegee surface of the solder printing mask 1, and the squeegee 202 is slid in the surface to supply the solder paste P into the opening 14 while rolling. The solder paste P is transferred onto the substrate 201.

  At this time, the solder printing mask 1 is elastically deformed following the shape of the step of the substrate 201 by the pressure of the squeegee 202 (squeegee pressure), and is firmly adhered to the substrate 201 in the vicinity of the step. Thereby, since the solder paste P is appropriately transferred to the substrate 201, high print quality is obtained.

  According to the first embodiment, the thickness of the resin layer can be freely set as compared with the conventional one. Therefore, the thickness of the metal plate 13 can be set while keeping the total thickness of the solder printing mask 1 constant. It can be made thinner than the resin layer. Thereby, it becomes possible to improve the followability of the solder printing mask 1 to the level difference of the substrate 201 during printing, and it is possible to improve the printing quality.

  Further, by using a polyimide sheet 11 having high mechanical strength and chemical resistance as a resin layer, it is possible to obtain a solder printing mask 1 that is not easily damaged by printing or washing in addition to the followability of the substrate. Become. Furthermore, since it has high heat resistance, there exists an effect that it can cut | disconnect appropriately with an ultraviolet-ray.

Embodiment 2
In the method of manufacturing the solder printing mask 1 in the second embodiment, the metal plate 13 prepared in advance is bonded to the resin layer in the first embodiment. The difference is that nickel plating is applied to form the metal plate 13 directly on the thermosetting adhesive sheet 12. Other configurations are the same as those in the first embodiment.

  FIG. 4 is a schematic process flow diagram showing a method for manufacturing the solder printing mask 1 according to the second embodiment. In this manufacturing process, first, the polyimide sheet 11 and the resin layer that is the thermosetting adhesive sheet 12 are temporarily bonded (step S11). The conditions for temporary bonding are the same as in step S2 of the first embodiment.

  Next, the resin layer is thermally cured (step S12). Thermosetting is the same as step S3 in the first embodiment.

  Next, the surface of the thermosetting adhesive sheet 12 opposite to the polyimide sheet 11 is subjected to nickel plating to form a metal plate 13 to make a metal / resin laminate (step S13). Here, the nickel plating includes the above-described electro nickel plating and electroless nickel plating without energization between the anode and the object to be plated. However, the thermosetting adhesive sheet 12 which is an electrically insulating material is energized. Therefore, the metal plate 13 cannot be directly formed on the thermosetting adhesive sheet 12 by electro nickel plating. On the other hand, electroless nickel plating does not require energization, and forms a plating film by the reaction of a reducing agent in the plating solution. Therefore, plating can be performed on an electrically insulating material such as a resin.

  In the second embodiment, first, a thin nickel film is formed on the thermosetting adhesive sheet 12 as a base for the metal plate 13 by electroless nickel plating. The thickness of this nickel film shall be 0.5-1.5 micrometers. Next, the metal plate 13 is formed on the underlying nickel film by electro nickel plating. At this time, as in the first embodiment, the thickness of the metal plate 13 is preferably less than ½ of the total layer, more preferably １ ／ or less, and 0.015 mm or more. Adjust the conditions.

  Next, as in step S4 of the first embodiment, an ultraviolet laser is irradiated from the resin layer side of the metal / resin laminate to form an opening with a predetermined pattern (step S14).

  According to the second embodiment, the thickness of the metal plate 13 is set to the thickness of the resin layer while keeping the total thickness of the printing mask constant by freely setting the thickness of the resin layer as compared with the conventional one. By making the thickness thinner than this, it becomes possible to manufacture the solder printing mask 1 having good print quality with high followability to the steps of the substrate of the solder printing mask 1 during printing by a simple method.

Embodiment 3
As shown in FIG. 5, the solder printing mask 2 according to the third embodiment has a single-layer structure in which the resin layer is composed only of the thermosetting adhesive sheet 21 and does not have the polyimide sheet 11. Unlike the first embodiment, the rest is the same. Therefore, description and reference numerals of the same configurations as those in Embodiment 1 are omitted.

  The thermosetting adhesive sheet 21 constituting the resin layer is an epoxy thermosetting adhesive sheet as in the first embodiment, and the thickness of the single body is 0.02 to 0.06 mm. In Form 2, since there is no polyimide sheet 11, a thicker one is used, or a desired thickness is overlapped.

  FIG. 6 is a schematic process flow diagram showing a method for manufacturing the solder printing mask 2 according to the third embodiment. The difference from Embodiment 1 is that the metal / resin laminate is not the polyimide sheet 11, the thermosetting adhesive sheet 12, and the metal plate 13 as in Step S2, but the thermosetting adhesive sheet 21 and the metal plate 22. In other respects, the configuration is essentially the same.

  That is, first, a metal plate 22 is prepared (step S21), and the metal plate 22 and a thermosetting adhesive sheet 21 thicker than this are overlapped to form a metal / resin laminate, and the same conditions as in the first embodiment. Then, pressure bonding is performed and temporary bonding is performed (step S22), followed by thermosetting (step S23), and an ultraviolet laser is irradiated from the resin layer side to form a predetermined pattern opening (step S24).

  According to the third embodiment, as in the first embodiment, the thickness of the resin layer can be freely set as compared with the conventional one, so that the total thickness of the solder printing mask 2 is kept constant. Since the thickness of the metal plate 22 can be made thinner than the thickness of the resin layer, the followability of the solder printing mask 2 to the level difference of the substrate 201 at the time of printing can be improved, and the printing quality can be improved. become.

  Furthermore, since the resin layer is a single layer and the polyimide sheet 11 is not used, the manufacturing cost can be reduced and the manufacturing process can be simplified compared to the first embodiment.

Embodiment 4
In the fourth embodiment, the solder printing mask 2 according to the third embodiment is manufactured by using a plating process similarly to the second embodiment, and the other points are the same.

  That is, first, a thermosetting adhesive sheet 21 is prepared (step S31), is thermally cured (step S32), a base is formed by electroless nickel plating, and then a metal plate 22 is formed by electro nickel plating ( In step S33), an ultraviolet laser is irradiated from the resin layer side to form a predetermined pattern of openings (step S34).

Embodiment 5
As shown in FIG. 8, the solder printing mask 3 according to the fifth embodiment has a single-layer structure in which the resin layer is composed only of the heat-fusible polyimide sheet 31. Unlike the first embodiment in that the sheet 21 is not provided, the rest is the same. Therefore, description and reference numerals of the same configurations as those in Embodiment 1 are omitted.

  The heat-fusible polyimide sheet 31 constituting the resin layer is a normal polyimide sheet made of the same material as that of the polyimide sheet 11 having a thermoplastic polyimide in the surface layer, and is heated under predetermined heat-fusing conditions. By applying pressure, it can be fused with other things. Although the thickness of a single body is 0.025 to 0.050 mm, it is possible to form a resin layer thicker than this by overlapping and sticking together with the heat-fusible polyimide sheets 31.

  FIG. 9 is a schematic process flow diagram showing a method for manufacturing the solder printing mask 3 according to the fifth embodiment. The difference from the first embodiment is that the metal / resin laminate is not the polyimide sheet 11, the thermosetting adhesive sheet 12 and the metal plate 13 as in step S 2, but the heat-fusible polyimide sheet 31 and the metal plate 32. The other points are essentially the same.

  That is, first, a metal plate 32 is prepared (step S41), a metal / resin laminate is formed by laminating the metal plate 32 and a thicker heat-fusible polyimide sheet 31, and then crimped (step S42). Then, an ultraviolet laser is irradiated from the resin layer side to form an opening having a predetermined pattern (step S43).

  According to the fifth embodiment, the thickness of the resin layer can be freely set as compared with the conventional one, as in the first embodiment, so that the total thickness of the solder printing mask 3 is kept constant. The thickness of the metal plate 32 can be made thinner than the thickness of the resin layer. As a result, the followability of the solder printing mask 3 to the level difference of the substrate 201 during printing can be improved, and the printing quality can be improved.

  Furthermore, since the resin layer is a single layer and the thermosetting adhesive sheet 12 is not used, temporary adhesion is unnecessary, and compared to the first embodiment, the manufacturing cost can be reduced and the process can be simplified.

Embodiment 6
In the sixth embodiment, the solder printing mask 3 according to the fifth embodiment is manufactured by using a plating process as in the second embodiment, and the other points are the same.

  That is, first, a heat-fusible polyimide sheet 31 is prepared (step S51), a base is formed thereon by electroless nickel plating, and then a metal plate 52 is formed by electric nickel plating (step S52). Then, an ultraviolet laser is irradiated to form an opening having a predetermined pattern (step S53).

  As mentioned above, although Embodiment 1-6 was demonstrated, this invention is not restricted to this, The other form from which the same effect is acquired is also included. For example, the polyimide sheet 11 can be replaced with another resin film such as a PET film.

  Moreover, although nickel was used for the metal in the metal plates 13, 22, and 32, any metal material generally used for a metal mask such as SUS304 may be used.

  In the sixth embodiment, the resin layer is not limited to the heat-fusible polyimide sheet 31, and a normal polyimide sheet 11 may be used.

1, 2, 3 Mask for solder printing 11 Polyimide sheet 12, 21 Thermosetting adhesive sheet (adhesive layer)
13, 22, 32 Metal layer (metal plate)
14 Opening 31 Heat-sealable polyimide sheet

Claims (1)

A step of curing a resin layer in which an epoxy thermosetting adhesive sheet having a thickness of 0.02 to 0.06 mm is overlaid to a desired thickness under predetermined curing conditions;
Forming a base made of a nickel plating film of 0.5 to 1.5 μm by electroless nickel plating on the resin layer;
Forming a metal / resin laminate by forming a metal layer on the base by performing nickel electroplating with a nickel thickness of 1/3 or less of the total thickness and 0.015 mm or more ;
Irradiating an ultraviolet laser from the resin layer side of the metal / resin laminate, processing the metal / resin laminate, and forming openings in a predetermined pattern;
A method for manufacturing a mask for solder printing, comprising:

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