JP6374217B2 - Metal mask and manufacturing method thereof - Google Patents

Description

  The present invention relates to a metal mask and a manufacturing method thereof.

  2. Description of the Related Art Conventionally, screen printing that enables high-precision pattern printing has been adopted when solder paste (cream solder), conductor paste, or the like is applied and formed on a printed wiring board for mounting various electronic components. In particular, when high-precision pattern printing is desired, a screen printing plate such as a metal mask is used as a plate material for screen printing.

  In screen printing using a metal mask, a squeegee or a press is applied from one surface (squeegee surface) to the other surface (surface on the substrate side) of the metal mask that is in contact with or slightly away from the surface of the substrate. Printing is performed on the surface of the printing material by extruding printing ink and other adhering materials from the pattern-shaped holes provided in the metal mask while being pressed against the surface of the printing material with pressure or the like. This printing method is suitable when the substrate is a flat plate.

  In recent years, with the miniaturization of electronic equipment or electronic components, the hole pattern provided in the metal mask for applying and forming solder paste on the printed wiring board is extremely fine and the distance between the holes (hole pitch) is small. It is becoming very short. In order to form a high-definition pattern, it is advantageous to basically make contact between the metal mask and the substrate.

  In this way, the metal mask with extremely fine holes densely contacts the printed material during printing, and the viscosity and surface tension of the solder paste and flux, and further, the printed surface of the printed material and the printed surface of the printed material. Due to the adhesive force due to the pressing of the sheet, it is in close contact with the substrate, and the separation of the plate is likely to deteriorate. If the both sides are forcibly peeled off in a state where the plate separation has deteriorated, the solder paste in the pattern-like holes will not come off to the printed material, and the solder paste will adhere to the inner walls of the holes, resulting in a printed pattern. It will cause the shape to collapse. In addition, the solder paste is scattered on the substrate to be printed, which may cause stains on the printed surface and bleeding of edges in the printed pattern shape.

  To date, various improvements have been made to improve the separation of metal masks. For example, a metal mask is manufactured with a plating bath composition in which citrate is added instead of boric acid as an additive to a nickel sulfamate bath. By doing so, a method of manufacturing a metal mask has been proposed in which the crystal has a fine crystal structure, the film hardness, surface roughness and Young's modulus are improved, and it is also environmentally friendly (see, for example, Patent Document 1).

JP 2008-213472 A

  When a metal mask is manufactured with a plating bath composition in which citrate is added instead of boric acid as an additive to a conventional nickel sulfamate bath, if the plating solution is used for a long time, sulfamic acid, nickel and citric acid The salt reacts to easily generate a green reaction product. The green reaction product adheres to the nickel electrode and the filter contained in the anode bag. When the green reaction product adheres to the nickel electrode, the current is deteriorated and the plating is not stably performed. Therefore, the nickel electrode was washed at a rate of once every one to two months. Further, when the filter is clogged, the plating solution is not filtered, and the surface of the plating film is roughened, resulting in poor plating. In addition, there is a problem that the average interval Sm of the unevenness of the surface roughness becomes large, and the eyes are rough and lack of uniformity.

  The present invention has been made to solve the above-described problems. By manufacturing a metal mask with a plating bath composition using citrate as an additive to a watt bath made of nickel sulfate and nickel chloride. The present invention provides a metal mask that can suppress generation of a green reaction product, has a small average interval Sm between irregularities of surface roughness, is fine, and is uniform, and a method for manufacturing the same.

  In the metal mask manufacturing method according to the present invention, a metal mask is manufactured by a plating bath composition using citrate as an additive in a watt bath made of nickel sulfate and nickel chloride.

  The plating bath composition includes nickel sulfate 100 to 400 g / L, nickel chloride 30 to 60 g / L, and citrate 15 to 40 g / L.

  Further, trisodium citrate is used as the citrate.

  The metal mask according to the present invention is manufactured by a plating bath composition using citrate as an additive in a watt bath made of nickel sulfate and nickel chloride.

  Also, a plating bath composition using citrate as an additive in a watt bath composed of nickel sulfate and nickel chloride, nickel sulfate 100 to 400 g / L, nickel chloride 30 to 60 g / L, citrate 15 to 40 g Includes / L.

  Further, trisodium citrate is used as the citrate.

  Further, the average interval Sm of the surface roughness irregularities of the metal mask is 23 μm or less.

  In addition, in the crystal orientation of the metal mask, the peak intensity ratio of the (220) plane to the sum of the peak intensity of the (111) plane, the (200) plane, and the (220) plane is 0.4 or more.

  According to this invention, the production of a green reaction product can be suppressed by producing a metal mask with a plating bath composition using citrate as an additive in a watt bath composed of nickel sulfate and nickel chloride. . Moreover, the average interval Sm of the surface roughness irregularities is small, the eyes are fine, and the surface roughness of the film is uniform. In the crystal orientation, the peak intensity ratio of the (220) plane to the sum of the peak intensity of the (111) plane, (200) plane, and (220) plane is 0.40 or more.

It is a characteristic diagram showing the film hardness of the metal mask manufactured by the manufacturing method of the metal mask (at a current density of 1A / dm ²⁾ in Embodiment 1 of the present invention. It is a table | surface which shows the film hardness (at the time of current density 1A / dm < ² >, 2A / dm < ² >) of the metal mask produced with the manufacturing method of the metal mask in Example 1 of this invention. It is a characteristic view which shows the film hardness (at the time of trisodium citrate 35g / L) of the metal mask produced with the manufacturing method of the metal mask in Example 1 of this invention. It is a table | surface which shows the film hardness (at the time of trisodium citrate 35g / L) of the metal mask produced with the manufacturing method of the metal mask in Example 1 of this invention. It is a characteristic view which shows the peak intensity ratio (at the time of trisodium citrate 30g / L, NTS3g / L) of the orientation of the crystal | crystallization of the metal mask produced with the manufacturing method of the metal mask in Example 1 of this invention. It is a table | surface which shows the peak intensity ratio (at the time of trisodium citrate 30g / L, NTS3g / L) of the orientation of the crystal | crystallization of the metal mask produced with the manufacturing method of the metal mask in Example 1 of this invention. It is a characteristic view which shows the surface roughness of the plating film of the metal mask produced with the manufacturing method of the metal mask in Example 1 of this invention. It is a table | surface which shows the surface roughness of the plating film of the metal mask produced with the manufacturing method of the metal mask in Example 1 of this invention. It is a characteristic view which shows the surface roughness of the plating film of the metal mask produced with the plating bath composition which added the citrate as an additive to the conventional nickel sulfamate bath as a comparative example. It is a table | surface which shows the surface roughness of the plating film of the metal mask produced with the plating bath composition which added the citrate as an additive to the conventional nickel sulfamate bath as a comparative example.

Example 1.
The metal mask manufacturing method according to the present invention is characterized in that a metal mask is manufactured by a plating bath composition using citrate as an additive in a plating bath (called a Watt bath) made of nickel sulfate and nickel chloride. Is. Examples of citrate include citric acid, ammonium citrate, trisodium citrate, disodium citrate, monosodium citrate, monopotassium citrate, tripotassium citrate, and trisodium citrate is preferred. is there.
That is, as an actual plating bath composition in Example 1, nickel sulfate is 100 to 400 g / L, preferably 200 to 300 g / L. The reason why the nickel sulfate is in the range of 100 to 400 g / L is that if it is less than 100 g / L, the current efficiency of metal deposition deteriorates, and even if it exceeds 400 g / L, the effect does not change. . Moreover, nickel chloride is 30-60 g / L, Preferably it is 40-50 g / L. The reason why nickel chloride is in the range of 30 to 60 g / L is that if it is less than 30 g / L, the current efficiency of metal deposition deteriorates, and even if it exceeds 60 g / L, the effect does not change. . Moreover, trisodium citrate is 15-40 g / L, Preferably it is 20-35 g / L. The reason why trisodium citrate is in the range of 15 to 40 g / L is that if it is less than 15 g / L, the pH fluctuation of the plating solution increases, and even if it exceeds 40 g / L, the effect does not change. is there. Moreover, NTS (1.36-6-Naphthalene trisulfonate sodium) is 0.5-4 g / L. The reason why NTS is in the range of 0.5 to 4 g / L is that if it is less than 0.5 g / L, the stress cannot be adjusted to an appropriate stress. If it exceeds 4 g / L, the compressive stress becomes too strong. Because. The pit inhibitor is 5 cc / L. As plating conditions, the current density is 0.5 to ^{2 A} / dm ² , and preferably 1 to ^{2 A} / dm ² . The reason for the range the current density of 0.5~2A / dm ^2, when it is less than 0.5A / dm ^2, and because the film becomes brittle, the thickness uniformity exceeds 2A / dm ² This is because it gets worse. Moreover, pH is 3.99-4.29. Furthermore, the liquid temperature is 35 to 55 ° C.

Thereby, a metal mask can be manufactured with the plating bath composition which uses trisodium citrate as an additive for the plating bath (watt bath) which consists of nickel sulfate and nickel chloride.
FIG. 1 is a characteristic diagram showing the film hardness (when the current density is 1 A / dm ² ) of a metal mask produced by the metal mask manufacturing method according to Example 1 of the present invention for each concentration of trisodium citrate, and FIG. is a table showing the film hardness of the metal mask (at a current density of 1A / dm ² and 2A / dm ²⁾ by the concentration of the trisodium citrate prepared by the production method of the metal mask in the first embodiment of. According to the characteristic diagram and tables, film hardness _{H V} of the metal mask, at a current density of 1A / dm ^2, the film hardness _{H V} in accordance with the amount of NTS (0.5~4.0g / L) It became the range of 421-464. Further, when the current density 2A / dm ^2, the addition amount of the NTS (1.5~4.0g / L) Film Hardness _{H V} according to become a range of 429 to 464. That is, the film hardness was not inferior to the case where a metal mask was produced with a plating bath composition in which citrate was added as an additive to a conventional nickel sulfamate bath.
3 and 4 are characteristic diagrams and tables showing the film hardness (when trisodium citrate is 35 g / L) of the metal mask produced by the method for producing a metal mask according to Example 1 of the present invention. According to the characteristic diagram and tables, film hardness _{H V} of the metal mask, at a current density of 1A / dm ^2, the film hardness _{H V} in accordance with the amount of NTS (1~4.0g / L) 429~ The range was 464. Further, when the current density 2A / dm ^2, the addition amount of the NTS (1.5~4.0g / L) Film Hardness _{H V} according to become a range of 429 to 464. That is, the film hardness was not inferior to the case where a metal mask was produced with a plating bath composition in which citrate was added as an additive to a conventional nickel sulfamate bath.
5 and 6 are characteristics showing the peak intensity ratio of the crystal orientation of the metal mask produced by the metal mask manufacturing method in Example 1 of the present invention (when trisodium citrate 30 g / L and NTS 3 g / L). It is a figure and a table | surface. In the crystal orientation, the peak intensity ratios of the (111) plane, (200) plane, and (220) plane with respect to the total peak intensity of the (111) plane, (200) plane, and (220) plane are shown. According to this characteristic diagram and table, in the orientation of the metal mask crystal, the peak intensity ratio is 30 mA / L of trisodium citrate and 3 g / L of NTS, and the current density (0.5-2 A / dm ² ). Accordingly, the peak intensity ratio of crystal orientation changes. Then, a metal mask having a fine crystal structure in which the peak intensity ratio of the (220) plane is 0.4 or more when the current density is 1.0 to 2.0 A / dm ² is obtained.
7 and 8 show the surface roughness of the plating film of the metal mask produced by the metal mask manufacturing method in Example 1 of the present invention (when trisodium citrate is 35 g / L and the current density is 1 A / dm ² ). It is a characteristic view and a table. In the figure, Ra: arithmetic average roughness, Rmax: maximum height, Rz: ten-point average roughness, Sm: mountain valley (unevenness) average interval, respectively. According to the characteristic diagram and table of the present invention, the arithmetic average roughness Ra of the surface roughness is 0.29 to 0.43 (μm), and the average is 0.36 (μm). The maximum height Rmax is 3.34 to 4.64 (μm), and the average is 4.12 (μm). The ten-point average roughness Rz is 2.86 to 3.86 (μm), and the average is 3.33 (μm). Yamatani (unevenness) average interval Sm is 16.7 to 23 (μm), the average is 19.83 (μm), which is a small value as a whole.
9 and 10 show, as comparative examples, the surface roughness of a plating film of a metal mask prepared with a plating bath composition in which citrate is added as an additive to a conventional nickel sulfamate bath (trisodium citrate 25 g / L). FIG. 6 is a characteristic diagram and a table showing a current density of 2 A / dm ² . In the figure, Ra: arithmetic average roughness, Rmax: maximum height, Rz: ten-point average roughness, Sm: mountain valley (unevenness) average interval, respectively. According to the characteristic diagram and table of this comparative example, the arithmetic average roughness Ra of the surface roughness is 0.46 to 0.6 (μm), and the average is 0.54 (μm). The maximum height Rmax is 6.18 to 7.4 (μm), and the average is 6.63 (μm). The ten-point average roughness Rz is 4.18 to 5.46 (μm), and the average is 4.82 (μm). Yamatani (unevenness) average interval Sm is 22.2 to 28.9 (μm), the average is 26.63 (μm), which is a large value as a whole. Since the average interval Sm of the valleys (irregularities) becomes large, the eyes are rough and the surface roughness of the film is not uniform.
That is, the arithmetic average roughness Ra, the maximum height Rmax, and the ten-point average roughness Rz of the surface roughness of the plating film of the metal mask produced by the method for producing a metal mask in Example 1 of the present invention are the same as those of the conventional sulfamic acid. Compared to the case where a metal mask is manufactured with a plating bath composition in which citrate is added as an additive to a nickel bath, the metal mask is slightly improved and has a small value, but it can be said that there is no such wide opening. However, the average roughness Sm of the surface roughness (unevenness) is significantly improved as compared with the case where a metal mask is manufactured with a plating bath composition in which citrate is added as an additive to a conventional nickel sulfamate bath. Since the value is small, there is an advantage that the surface is fine and the surface roughness of the film is uniform.

As described above, when a metal mask is produced by a plating bath composition using citrate, particularly trisodium citrate, as an additive in a nickel sulfate and nickel chloride plating bath, there are the following advantages.
Even when the plating solution is used for a long time, the generation of a green reaction product can be suppressed. Conventionally, when the green reaction product adheres to the nickel electrode in the anode back, the current is deteriorated and the plating is not stably performed, so the nickel electrode was washed once or twice a month. It has been found that it is not necessary to wash for a long period of several months. In addition, the filter does not become clogged for a long time. Moreover, the average interval Sm of the surface roughness irregularities is as small as about 15 to 23 (μm), and the surface roughness of the film is uniform with fine eyes. In the crystal orientation, the peak intensity ratio of the (220) plane to the sum of the peak intensity of the (111) plane, (200) plane, and (220) plane is 0.40 or more. Also, the film strength was not inferior to the case where a metal mask was produced with a plating bath composition in which citrate was added as an additive to a conventional nickel sulfamate bath.

Claims (8)

  A method for producing a metal mask, comprising producing a metal mask by a plating bath composition using citrate as an additive in a Watt bath composed of nickel sulfate and nickel chloride. A method for producing a metal mask by a plating bath composition using citrate as an additive to a watt bath composed of nickel sulfate and nickel chloride,
A method for producing a metal mask, comprising, as the plating bath composition, nickel sulfate 100 to 400 g / L, nickel chloride 30 to 60 g / L, and citrate 15 to 40 g / L.   The metal mask manufacturing method according to claim 1 or 2, wherein trisodium citrate is used as the citrate.   A metal mask produced by a plating bath composition using citrate as an additive in a watt bath composed of nickel sulfate and nickel chloride. Menu as Tsu key bath composition, the metal mask according to claim 4, characterized in that it comprises nickel sulfate 100 to 400 g / L, nickel chloride 30 to 60 g / L, citrate 15 to 40 g / L.   6. The metal mask according to claim 4, wherein trisodium citrate is used as the citrate.   The metal mask according to any one of claims 4 to 6, wherein an average interval Sm of unevenness of the surface roughness of the metal mask is 23 µm or less.   The crystal mask orientation of the metal mask is characterized in that the peak intensity ratio of the (220) plane to the sum of the peak intensity of the (111) plane, the (200) plane and the (220) plane is 0.4 or more. The metal mask according to any one of claims 4 to 7.

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