KR102107599B1 - Menufacturing method for three-dimensional shape metal mask using electroforming - Google Patents

Abstract

The present invention relates to a method of manufacturing a three-dimensional shape metal mask using electroplating, and provides a metal mask capable of applying a COB or a lead frame mask with curvature with excellent precision, high printability, and durability. It is an object of the present invention.

Description

Method of manufacturing a three-dimensional metal mask using electroplating {MENUFACTURING METHOD FOR THREE-DIMENSIONAL SHAPE METAL MASK USING ELECTROFORMING}

The present invention relates to a method for manufacturing a three-dimensional metal mask using electroforming plating (electroforming), and more specifically, a surface mount mounting surface COB substrate or a bend (concave or convex) It relates to a method for manufacturing a three-dimensional electroplated metal mask used when printing solder paste on a lead frame with).

In general, the process of attaching a solder paste to a printed circuit after attaching ultra-small high-integrity circuit mounting components such as ICs and LSIs on a printed circuit board (PCB) or a chip on board (COB) board Is called Surface Mounter Technology (SMT), and this surface mount technology is a metal mask (Metal) that forms an opening (through hole) for a pad according to various pad shapes on a printed circuit board composed of pads and resistors. Mask), and through the space between the mask and the PCB, the solder cream called solder paste is pushed into the aperture while applying appropriate pressure to the pad of the PCB substrate. Only the required amount of paste is applied.

Subsequently, the IC is attached to each pad on the substrate and other microelectronic components are transferred to a reflow soldering open, and soldering is performed by applying heat above the paste melting temperature. At this time, since the printed solder paste amount compared to the area ratio of the substrate pad is determined by the area ratio of the metal mask opening, the dimensional accuracy of the metal mask, the positioning accuracy, and the omission of the aperture wall are: It is very important for surface mount printing quality.

Briefly, a metal mask means a thin metal plate (20 to 100 µm thick) that prints solder fades, and the role of the methyl mask is to quantitatively apply a certain amount of solder paste on the PCB substrate pad at the correct location. .

The conventional method of manufacturing a metal mask is to directly open the CAM data using a laser on a metal plate (mainly a stainless steel (SUS) plate) to form an opening directly, or apply a photoresist such as a photolithography process to a metal plate and apply a photo. After exposing through a mask to form and develop a pattern, chemically photo-etching to form openings. Alternatively, after forming the patterning by a photolithography process on a plate such as a glass plate or a metal plate, a thin metal film (Metal Layer) was formed by vacuum metallizing or electroplating.

However, among the metal masks manufactured by the conventional method, due to the laser characteristics, the metal plate opening is melted by heat due to the laser characteristics and the laser-processed portion is warped (twister), damaged (or heat discolored), The wall surface of the opening through which the laser is penetrated is rough, and burrs remain at the bottom of the opening, so the surface of the opening is not uniform and not smooth, so the solder paste does not come off even after surface treatment such as electropolishing. There was a problem in that it was difficult to quantitatively apply the paste to the correct position on the printed board (PCB).

In addition, the photo-etching method is chemically corroded and the surface of the opening is soft and clean compared to laser processing, so the surface quality is excellent, but after photolithography, the photo-etching process causes pressure spraying from the top and bottom of the metal plate during the photo-etching process. It has the characteristics of an hourglass shape, which causes fine interference when printing solder paste.

However, the metal mask manufactured by the conventional method has low precision and does not conform to the trend toward miniaturization and thinning, and a burr is formed in the opening processed by laser, so that the surface of the opening is not constant or smooth, so that the solder paste can be removed. There is a problem in that it is not excellent and it is difficult to quantitatively apply the solder paste to the correct position on the printing substrate.

In addition, the prior art is limited to the processing of the flat mold plate, and there is a limitation in the production of a metal mask having a recess or a protrusion, and when processing a metal plate having a recess or a protrusion, the dimensional accuracy and the position accuracy are not accurate. In recent years, the photolithography process is more precise than laser processing or photo-etching processing for the printing of ultra-small parts, high integrated circuit (HIC), wafer level package (WLP), wafer level chip scale package (WLCSP), LED package, and COB. The application of Jeonju plating process is expanding.

The present invention is to provide a three-dimensional shape metal mask using electroforming (Electro-forming), and has excellent dimensional and positional precision, high printability and durability, and provides a COB (Chip On Board) substrate or a bend (concave or It is an object of the present invention to provide a three-dimensional electroplated metal mask used for solder paste printing on a lead frame with convex portions).

The present invention is a three-dimensional metal mask manufacturing method having a solder paste opening, comprising: a shape manufacturing step of providing a concave-convex portion to a flat mold plate; A pattern forming step of forming a resist layer corresponding to a solder paste opening on the surface of the mold plate on which the uneven portion is formed; A plating step of immersing the mold plate in which the uneven portion is formed in potassium bichromate (K ₂ Cr ₂ O ₇ ) solution, and then forming a plating layer on the surface of the mold plate where the resist layer is not formed; And it is an aspect of the present invention to provide a three-dimensional metal mask manufacturing method comprising a mask separation step of separating the plating layer.

In addition, the present invention is a three-dimensional metal mask manufacturing method having a solder paste opening, the shape manufacturing step of providing a concavo-convex portion to the flat mold plate; A plating step of forming a plating layer on the surface of the mold plate after immersing the mold plate in which the uneven portion is formed in a solution of potassium dichromate (K ₂ Cr ₂ O ₇ ); A mask separation step of separating the plating layer; And it is another aspect of the present invention to provide a metal mask manufacturing method of a three-dimensional shape comprising the step of forming a solder paste opening on the mask surface.

The step of manufacturing the shape of the three-dimensional structure includes: (a) forming a concave-convex portion by CNC machining or photo etching on a flat-type mold plate or laminating a resist layer forming a concave-convex portion on the flat-type mold plate; (b) may include the step of imparting conductivity to the surface of the resist layer corresponding to the opening in the flat mold plate or the flat mold plate having the uneven portion, wherein the step (b) is silver mirror plating (silver mirror plating) or It may be to impart conductivity by a sputtering process.

In the plating step, the concentration of the potassium dichromate (K ₂ Cr ₂ O ₇ ) solution is 5 to 20%, and the metal plate may be immersed for 10 seconds to 10 minutes.

In the plating step, a plating layer may be formed using a plating solution containing nickel (Ni) and cobalt (Co), and the plating solution may further include a plating varnish.

The present invention provides a metal mask through electroplating using a pre-formed three-dimensional shape structure, so that the surface of the opening is smooth, and the solder paste is excellent in detachability, and high precision can be achieved, and the thickness of the plating layer can be adjusted. This has an easy effect.

In addition, by implementing high precision, there is an effect capable of manufacturing a metal mask that can be applied to various electronic devices.

Figure 1 shows a process diagram of a method of manufacturing a three-dimensional metal mask according to an embodiment of the present invention.
Figure 2 shows a schematic diagram of a method of manufacturing a three-dimensional metal mask according to one embodiment of the present invention.
Figure 3 shows a process diagram of a method of manufacturing a three-dimensional metal mask according to another aspect of the present invention.
4 is a schematic diagram of a method of manufacturing a 3D metal mask according to another aspect of the present invention.
Figure 5 shows an embodiment of a three-dimensional metal mask manufacturing method of the present invention.
FIG. 6 illustrates an embodiment of a method for manufacturing a metal mask manufactured through CNC machining in the method for manufacturing a three-dimensional metal mask of the present invention.
7 shows an embodiment of a method of manufacturing a metal mask manufactured through an etching process in the method of manufacturing a 3D metal mask of the present invention.
FIG. 8 shows an embodiment of a method of manufacturing a metal mask manufactured through a patterning process in the method of manufacturing a 3D metal mask of the present invention.

Hereinafter, the present invention will be described in detail.

The present invention is a three-dimensional shape having an uneven portion (concave or convex) having a constant depth and dimension to match the height and dimensions of the patterned openings and mounted parts to print the solder paste. It relates to a method of manufacturing an electroplated metal mask.

1 and 2, a three-dimensional metal mask manufacturing method having a solder paste opening according to one embodiment of the present invention is a shape manufacturing step of forming the uneven portion 111 on the flat mold plate 110 (S110); A pattern forming step (S120) of forming a resist layer 120 corresponding to the solder paste opening on the surface of the mold plate 110; A plating step (S130) of forming a plating layer 130 by using electroplating on the surface of the mold plate on which the resist layer is not formed; And a mask separation step (S140) of peeling the resist layer 120 and separating the plating layer 130 from the mold plate 110.

3 and 4, a method of manufacturing a three-dimensional metal mask having a solder paste opening according to another aspect of the present invention includes a flat mold plate 210 and a flat mold plate with irregularities 211. A shape manufacturing step to be granted (S210); A plating step (S220) of forming a plating layer 230 by using electroforming on the surface of the mold plate 210; A mask 200 separating step of separating the plating layer 230 (S230); And forming a solder paste opening 210 on the surface of the mask 200 (S240).

Shape manufacturing step (S110, S210) of the three-dimensional structure of the present invention is a step of preparing a conductive electroforming model, it is preferable that the mold plate (110, 210) is easy to separate from electroplating, the conductive electroforming model The material of the mold plates 110 and 210 is preferably stainless steel (SUS), and a metal material including iron (Fe), copper (Cu), nickel (Ni), aluminum (Aluminium), or other alloys (Metal Substrate) Can be In addition, the electroforming model may include non-conductive materials such as glass plates and resin films, and in the case of non-conductive materials, conductive materials such as silver, nickel, chromium, and indium tin oxide (ITO) are used. It can be used as an electroforming model by coating electroconductive film by silver hard plating or sputtering to impart conductivity to enable electroforming.

Forming the uneven portion of the present invention or the shape manufacturing step of the three-dimensional structure (S110, S210) is a flat mold plate (110) by patterning (patterning) of CNC (Computer Numerical Control) processing, etching (etching) process or photolitho process , 210) by forming the uneven portions 111 and 211, a three-dimensional shape can be formed on the metal plate.

More specifically, a concave portion or a convex portion can be formed at a predetermined location by CNC machining using the designed CAM data (CNC machining), or a photoresist layer is coated on a flat mold plate 110 and 210 and photo By irradiating with UV light through a mask (not used in the LDI exposure machine) and exposing and developing it, photo-etching is performed on only the part corresponding to the concavo-convex (concave or convex) 111, 211, so that the concave or convex at the specified position It can be formed (etching process) or coated with a resist layer, which is a photoresist layer, on the flat mold plates 110 and 210, and exposed and developed by irradiating with UV light through a photomask (not used in the LDI exposure machine). After forming a pattern portion corresponding to the concavo-convex portion (concave portion or convex portion) 111 and 211, an electroforming model may be formed by imparting conductivity (patterning process) by silver hardening or sputtering.

Referring to Figure 5, the shape manufacturing step (S110, S210) of forming the uneven portion through the patterning (patterning) of the present invention, preferably (a) the uneven portion 112, the flat mold plate (110, 210) 212) stacking the resist layers 121 and 221 to form; And (b) imparting conductivity to the surfaces of the resist layers 121 and 221 and the flat mold plates 110 and 210.

At this time, in the shape manufacturing steps (S110, S210) of forming the uneven portions 112, 212 through the patterning, the step (a) is the resist layers 121, 221 for the flat mold plates 110, 210 ) Is stacked at the level of the thickness of the chip in the PCB or COB, and then a pattern can be formed through a development process using a pattern exposure process and a developer. The resist layer regions to be retained through the pattern exposure process are cured, and the remaining regions 112 and 213 except for the cured resist layer regions are removed through the development process to form the uneven portions 112 and 212, which are the remaining resist layers. can do. On the other hand, the pattern exposure process is preferably using a LDI (Laser Direct Imaging) process that can reduce the process step and increase the precision, the developer is preferably 1% sodium carbonate (Na ₂ CO ₃ ). In addition, the step (b) may impart conductivity by silver mirror plating or sputtering.

The pattern forming step (S120) according to an embodiment of the present invention is a step of determining the shape of the opening through which the solder paste penetrates, with respect to the mold plate 110 on which the uneven portion 111 is formed. In more detail, after coating the resist layer 120 with respect to the mold plate 110 on which the uneven portion 111 is formed, a solder paste opening area and a plating layer are formed through a pattern exposure process and a developing process using a developer. The area to be determined can be determined. Through the pattern exposure process, a resist layer region 113 to be retained is determined and a region 115 in which a plating layer is to be formed is formed through a development process. On the other hand, the remaining resist layer region 113 does not form a plating layer and forms a solder paste opening through peeling of the resist layer. The developer is preferably 1% sodium carbonate (Na ₂ CO ₃ ).

In more detail, the pattern exposure process may use a photomask process or a laser direct imaging (LDI) process. The photomask process is a photomask designed for coating the resist layer 120 on the surface of the mold plate 110 on which the uneven portion (concave portion or convex portion) 111 is formed, and forming an opening corresponding to solder paste printing. After exposure by irradiating UV light through, when developing, the portion irradiated with light is removed, and the portion not irradiated with light exists in the form of a pattern to form a pattern. On the other hand, it is preferable to use a LDI (Laser Direct Imaging) process that can reduce process steps and increase precision.

Plating layer forming step of the present invention (S130, S220) is to perform electroplating using a nickel (Ni) and cobalt (Co) mixed alloy solution as a plating solution, the resist layer 120 is present in the pattern forming step (S120) This is a step of forming plating layers 130 and 230 of a certain thickness by using electroforming for the region 115 which is not.

The plating solution may further include a plating varnish, and the plating varnish may include saccharin (C ₇ H ₄ NNaO ₃ S ㅇ H ₂ O). By further comprising a plating varnish, it is possible to adjust the tensile stress of the plating layer according to electroforming.

More preferably, it is preferable to form a plating layer after immersing the mold plates 110 and 210 in 5 to 20% potassium dichromate (K ₂ Cr ₂ O ₇ ) solution for 10 seconds to 10 minutes at room temperature. By immersing in potassium dichromate (K ₂ Cr ₂ O ₇ ) solution, a chromium compound is formed on the surfaces of the mold plates 110 and 210, thereby facilitating separation of the mold plates 110 and 210 and the plating layers 130 and 230. It is possible to minimize damage to the metal mask when the plating layer is separated.

On the other hand, in the plating layer forming step (S130) according to one embodiment of the present invention, when the plating layer 130 is formed, a plating layer is not formed in the solder paste opening predetermined by the resist layer 120, and the region 115 other than the resist layer is formed. By forming the plating layer 130 only, a metal mask body having a three-dimensional shape can be formed. In addition, since the solder paste opening is formed when the resist layer 120 is peeled, unlike the laser cut method, no burr is generated, and thus a metal mask having excellent peelability of the solder paste can be provided.

In the mask separation step (S140, S230) of the present invention, the plating layer (130, 230) formed in the plating layer forming step (S130, S220) is completely separated from the mold plate 110, which is an electroforming model, without damage such as wave, packing, and tear. It is a step.

In the opening forming step S240 according to another aspect of the present invention, an opening through which a solder paste can penetrate can be directly formed on the surface of the three-dimensional shape mask separated in the mask separation step S230 by laser cutting or the like. . An aperture corresponding to solder paste printing may be formed on the separated mask surface through laser processing or photo etching.

Hereinafter, the present invention will be described in more detail by examples. However, the present invention is not limited by the examples.

Example 1. Formation of a 3D structure through CNC machining

Referring to FIG. 6, a concavo-convex portion is formed on a SUS metal plate through CNC machining to manufacture a three-dimensional shape structure (three-dimensional shape production). Then, immersed in an alkali solution of 50 to 60 ℃, washed with water and dried. Thereafter, after coating with a 3D mask thickness to produce a dry film resist layer (DFR) through roll coating (roll temperature 120 ° C, roll pressure 0.3 Mpa, coating speed 1.0 m / min), the light amount is about 70 to 500 mj. After performing the LDI (Laser Direct Imaging) pattern exposure, it is washed with 1% sodium carbonate (Na ₂ CO ₃ ) and washed with water (pattern formation). Subsequently, the structure of the three-dimensional shape with the plating layer was immersed in a solution of 5 to 20% potassium dichromate (K ₂ Cr ₂ O ₇ ) at room temperature for 10 seconds to 10 minutes, and then the surface of the three-dimensional shape was formed. A plating layer is formed by electroplating using a Ni and Co alloy plating solution to which saccharin (C ₇ H ₄ NNaO ₃ S ㅇ H ₂ O) is added as a plating varnish (plating layer formation). Thereafter, the dry film resist sheet layer (DFR) is peeled off using a 1 to 10% NaOH or KOH solution in a three-dimensional shape structure having a plating layer. Thereafter, the three-dimensional metal mask as a plating layer is separated from the metal plate (metal mask separation).

Example 2 Formation of a 3D structure through etching

Referring to FIG. 7, the SUS metal plate is immersed in an alkali solution of 50 to 60 ° C., followed by washing with water and drying. Subsequently, after coating the dry film resist layer (DFR) on the surface of the metal plate through roll coating (roll temperature 120 ° C., roll pressure 0.3 Mpa, coating speed 1.0 m / min), LDI (Laser at a light amount of about 70 to 500 mj) Direct Imaging) After performing pattern exposure, it is developed with 1% sodium carbonate (Na ₂ CO ₃ ), washed with water, and then etched with ferric chloride solution (FeCl ₃ ㅇ 6H ₂ O) to form irregularities, The dry film resist layer is peeled to produce a three-dimensional shape structure (three-dimensional shape production). Thereafter, after coating with a 3D mask thickness to produce a dry film resist layer (DFR) through roll coating (roll temperature 120 ° C, roll pressure 0.3 Mpa, coating speed 1.0 m / min), the light amount is about 70 to 500 mj. After performing the LDI (Laser Direct Imaging) pattern exposure, it is washed with 1% sodium carbonate (Na ₂ CO ₃ ) and washed with water (pattern formation). Thereafter, the structure of the three-dimensional shape with the plating layer is immersed in 5 to 20% potassium dichromate (K ₂ Cr ₂ O ₇ ) solution for 10 seconds to 10 minutes at room temperature, and then the surface of the three-dimensional shape A plating layer is formed by electroplating using a Ni and Co alloy plating solution to which saccharin (C ₇ H ₄ NNaO ₃ S ㅇ H ₂ O) is added as a plating varnish (plating layer formation). Thereafter, the dry film resist sheet layer (DFR) is peeled off using a 1 to 10% NaOH or KOH solution in a three-dimensional shape structure having a plating layer. Thereafter, the three-dimensional metal mask as a plating layer is separated from the metal plate (metal mask separation).

Example 3 Formation of a 3D structure through patterning

Referring to FIG. 8, the SUS metal plate is immersed in an alkali solution of 50 to 60 ° C., followed by washing with water and drying. Thereafter, after coating the dry film resist layer (DFR) on the surface of the metal plate by the height of the cap of the three-dimensional mask through roll coating (roll temperature 120 ° C., roll pressure 0.3 Mpa, coating speed 1.0 m / min), the amount of light is about 70 After performing the LDI (Laser Direct Imaging) pattern exposure from 500 to mj, it was developed with 1% sodium carbonate (Na ₂ CO ₃ ) and washed with water to produce a three-dimensional shape structure having irregularities. Then, a silver solution mixed with 25 g / L of silver nitrate (AgNO ₃ ) and 100 ml / L of ammonia water and glyoxal (C ₂ H ₂ O ₂ ) 20 ml / L and triethanolamine (C ₆ H ₁₅ NO ₃ ) on the surface of the three-dimensional structure ) By spraying a reducing solution mixed with 8ml / L with a two-head spray gun, silver is deposited to perform conductivity by performing a silver-plating process in which a conductive film is formed (three-dimensional shape production). 3D mask thickness coated to produce a dry film resist layer (DFR) through roll coating (roll temperature 120 ° C, roll pressure 0.3 Mpa, coating speed 1.0 m / min) on the structure surface of the 3D formation with conductivity. Thereafter, after performing an LDI (Laser Direct Imaging) pattern exposure operation with a light amount of about 70 to 500 mj, development is performed with 1% sodium carbonate (Na ₂ CO ₃ ) and washed with water (pattern formation). Subsequently, the structure of the three-dimensional shape with the plating layer was immersed in a solution of 5 to 20% potassium dichromate (K ₂ Cr ₂ O ₇ ) at room temperature for 10 seconds to 10 minutes, and then the surface of the three-dimensional shape was formed. A plating layer is formed by electroplating using a Ni and Co alloy plating solution to which saccharin (C ₇ H ₄ NNaO ₃ S ㅇ H ₂ O) is added as a plating varnish (plating layer formation). Thereafter, the dry film resist sheet layer (DFR) is peeled off using a 1 to 10% NaOH or KOH solution in a three-dimensional shape structure having a plating layer. Thereafter, the three-dimensional metal mask (mask separation), which is a plating layer, is separated from the metal plate.

Example 4 Formation of a 3D structure through patterning

Referring to FIG. 8, the SUS metal plate is immersed in an alkali solution of 50 to 60 ° C., followed by washing with water and drying. Thereafter, after coating the dry film resist layer (DFR) on the surface of the metal plate by the height of the cap of the three-dimensional mask through roll coating (roll temperature 120 ° C., roll pressure 0.3 Mpa, coating speed 1.0 m / min), the amount of light is about 70 After performing the LDI (Laser Direct Imaging) pattern exposure from 500 to mj, it was developed with 1% sodium carbonate (Na ₂ CO ₃ ) and washed with water to produce a three-dimensional shape structure having irregularities. Subsequently, a sputtering process of forming a Cr film thickness of 1000 Å to 1500 하여 by working with 8 kw of power after injecting 1.0 x 10 ^-3 torr, Ar of a vacuum chamber of 200 sccm into the vacuum chamber based on Cr metal on the surface of the three-dimensional shape structure. To impart conductivity (three-dimensional shape production). 3D mask thickness coated to produce a dry film resist layer (DFR) through roll coating (roll temperature 120 ° C, roll pressure 0.3 Mpa, coating speed 1.0 m / min) on the structure surface of the 3D formation with conductivity. Thereafter, after performing an LDI (Laser Direct Imaging) pattern exposure operation with a light amount of about 70 to 500 mj, development is performed with 1% sodium carbonate (Na ₂ CO ₃ ) and washed with water (pattern formation). Subsequently, the structure of the three-dimensional shape with the plating layer was immersed in a solution of 5 to 20% potassium dichromate (K ₂ Cr ₂ O ₇ ) at room temperature for 10 seconds to 10 minutes, and then the surface of the three-dimensional shape was formed. A plating layer is formed by electroplating using a Ni and Co alloy plating solution to which saccharin (C ₇ H ₄ NNaO ₃ S ㅇ H ₂ O) is added as a plating varnish (plating layer formation). Thereafter, the dry film resist sheet layer (DFR) is peeled off using a 1 to 10% NaOH or KOH solution in a three-dimensional shape structure having a plating layer. Thereafter, the dry film resist sheet layer (DFR) is peeled with 1 to 10% NaOH or KOH solution, and a three-dimensional metal mask (mask separation), which is a plating layer, is separated from the metal plate.

As described above, since a specific part of the present invention has been described in detail, it is obvious to those skilled in the art that this specific technique is only a preferred embodiment, and the scope of the present invention is not limited thereby. something to do. Therefore, the substantial scope of the present invention will be defined by the appended claims and their equivalents.

Claims (6)

In the method of manufacturing a metal mask for three-dimensional screen printing having a solder paste opening,
A shape manufacturing step of providing a concavo-convex portion to the flat mold plate by CNC processing or patterning of a photolitho process;
A pattern forming step of forming a resist layer corresponding to a solder paste opening on the surface of the mold plate on which the uneven portion is formed;
A plating step of immersing the mold plate in which the uneven portion is formed in potassium bichromate (K ₂ Cr ₂ O ₇ ) solution, and then forming a plating layer on the surface of the mold plate where the resist layer is not formed; And
Method of manufacturing a metal mask of a three-dimensional shape comprising a mask separation step of separating the plating layer.
delete According to claim 1,
The shape manufacturing step,
(a) laminating a resist layer forming an uneven portion on a flat mold plate;
(b) A method of manufacturing a metal mask of a three-dimensional shape, comprising the step of imparting conductivity to the surface of the resist layer and the flat mold plate.
According to claim 1,
In the plating step, the concentration of the potassium dichromate (K ₂ Cr ₂ O ₇ ) solution is 5 to 20%, and the metal mask manufacturing method of the three-dimensional shape is characterized in that the metal plate is immersed for 10 seconds to 10 minutes.

According to claim 1,
The plating step is a three-dimensional metal mask manufacturing method, characterized in that using a plating solution containing nickel (Ni) and cobalt (Co).
The method of claim 5,
The plating solution is a three-dimensional metal mask manufacturing method characterized in that it further comprises a plating varnish.

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