JP2023143968A - Mask for arrangement - Google Patents

Abstract

To provide a mask for arrangement that can prevent poor mounting of solder balls.SOLUTION: A mask for arrangement in which solder balls 2 are placed at a predetermined position on a workpiece 3 by placing the solder balls 2 into a through holes 12 corresponding to a predetermined arrangement pattern includes a mask body 10 in which the through hole 12 is formed. At least the squeegee surface of the mask body 10 is provided with a coating layer made of fluororesin, silicone resin, emulsion, resist, or acrylic resin.SELECTED DRAWING: Figure 1

Description

The present invention relates to an array mask used, for example, to form solder bumps.

Solder bump formation methods include a printing process in which flux is applied to electrodes on a workpiece such as a wafer, flexible board, or rigid board, an arrangement process in which solder balls are arranged on the flux, and a heating process in which the solder balls are heated and melted. Bumps are formed through a process. In the above-mentioned arranging process, there is a transfer method using a mask as a method for arranging the solder balls on the workpiece. In the transfer method, solder balls are placed on the workpiece using an array mask (hereinafter simply referred to as a "mask") that has positioning holes through which the solder balls can be inserted in accordance with the electrode array pattern of the workpiece. It is mounted on the electrode. Specifically, after aligning the mask with respect to the workpiece so that the through holes and electrodes match, the solder balls supplied onto the mask are swept with a squeegee or brush, and applied to each through hole. Insert solder balls one by one. By fixing the solder ball to the flux, the solder ball is temporarily mounted at a predetermined position on the workpiece.

Such a mask is disclosed in Patent Document 1. The mask described in Patent Document 1 is provided with a large number of supporting protrusions on the lower surface of a mask main body having a through hole, and the protruding dimensions of the protrusions are set to be the same. As a result, when the mask is installed on the workpiece, the lower ends of all the supporting protrusions come into contact with the top surface of the workpiece, ensuring a gap between the mask body, which has a through hole, and the workpiece. ing.

JP2006-287215A

However, in recent years, as electronic devices have become smaller, bumps have become smaller. In other words, as bumps become smaller, the through-hole spacing and pattern area spacing in the mask become narrower, and the external dimensions of the protrusions themselves arranged between the through-holes and pattern areas (at the outer periphery of the pattern area) also become smaller. As a result, the distance between the mask and the workpiece is narrowed, and the flux placed on the electrodes of the workpiece tends to adhere to the mask. If flux adheres to the surface of the mask, solder ball mounting problems are likely to occur. SUMMARY OF THE INVENTION An object of the present invention is to provide an array mask that can prevent solder ball mounting defects.

The present invention is an array mask that mounts solder balls 2 at predetermined positions on a workpiece 3 by depositing the solder balls 2 into the through holes 12 corresponding to a predetermined array pattern. The mask body 10 includes a mask body 10 in which a large number of regions are formed, and a protrusion 15 provided on the side of the mask body 10 facing the workpiece 3, and a coating layer 50 is formed at least on the lower surface of the mask body 10. Features. Further, the mask main body 10 and the protrusion 15 are formed separately. Further, the coating layer 50 is formed to cover the lower surface of the mask body 10 and the surface of the protrusion 15. This coating layer 50 is preferably formed with a thickness of 1 μm or less.

Further, the present invention includes a mask body 10 in which a large number of pattern areas each consisting of through holes 12 are formed, and a protrusion 15 provided on the side of the mask body 10 facing the work 3, so that at least the lower surface of the mask body 10 has a protrusion 15. , a method for manufacturing an array mask on which a coating layer 50 is formed. First, a primary pattern resist 41 having a resist body 41 a is formed on a matrix 40 . Next, a primary electrodeposition layer 42 is formed on the matrix 40 using the resist body 41a. Next, a secondary pattern resist 44 having a resist body 44a is formed on the primary electrodeposition layer 42. Next, a coating layer 50 is formed on the surface of the primary electrodeposition layer 42. This coating layer 50 is preferably formed on the surface of the primary electrodeposited layer 42 on the side having the secondary pattern resist 44 and on the surface of the secondary pattern resist 44.

According to the array mask of the present invention, since the coating layer is formed on the lower surface of the mask body, it is possible to prevent flux from remaining attached to the lower surface of the mask body. In addition, by forming a coating layer to cover the lower surface of the mask body and the surface of the protrusions, the coating layer functions as a protective layer for the protrusions, preventing the protrusions from falling off, deforming, or being damaged. can.

FIG. 1 is a perspective view showing the overall configuration of an array mask and a workpiece according to the present invention. FIG. 2 is a longitudinal cross-sectional side view of the array mask according to the first embodiment of the present invention. FIG. 2 is a plan view of the array mask according to the first embodiment of the present invention. FIG. 6 is a longitudinal sectional side view of another embodiment of the array mask according to the first embodiment of the present invention. FIG. 7 is a plan view of another embodiment of the array mask according to the first embodiment of the present invention. FIG. 6 is a longitudinal sectional side view of another embodiment of the array mask according to the first embodiment of the present invention. FIG. 3 is an explanatory diagram of a method for manufacturing an array mask according to the first embodiment of the present invention. FIG. 3 is an explanatory diagram of a method for manufacturing an array mask according to the first embodiment of the present invention. FIG. 7 is a vertical side view of an array mask according to a second embodiment of the present invention. It is an explanatory view of the manufacturing method of the array mask concerning a 2nd embodiment of the present invention. It is an explanatory view of the manufacturing method of the array mask concerning a 2nd embodiment of the present invention. FIG. 7 is a partially enlarged plan view of an array mask according to another embodiment of the present invention. It is a partially enlarged vertical cross-sectional side view of another embodiment of the array mask according to the second embodiment of the present invention. It is an explanatory view of the manufacturing method of another embodiment of the array mask concerning a 2nd embodiment of the present invention.

(First embodiment)
1 to 3 show a mask for arranging solder balls according to a first embodiment of the present invention. This arranging mask (hereinafter simply referred to as mask) 1 is used in the step of arranging solder balls 2 in forming solder bumps. In FIG. 2, reference numeral 3 indicates a workpiece to which solder balls 2 are mounted using the mask 1. This work 3 is made by mounting a plurality of semiconductor chips 5 on a base 4 of, for example, a glass epoxy substrate, wiring them with wire bonds, and then sealing them by transfer molding. Electrodes 6, which are input/output terminals, are formed on the upper surface of 3 in a predetermined pattern. Note that after the bumps are formed, the workpiece 3 is cut into individual pieces to form individual LSI chips.

As shown in FIG. 1, the mask 1 consists of a mask body 10 made of nickel, a nickel alloy such as nickel-cobalt, copper, or other metal. 11 can be installed. At the center of the mask body 10, a large number of pattern areas are formed corresponding to each semiconductor chip 5, each consisting of a large number of independent through holes 12 into which solder balls 2 are inserted. As shown in FIG. 2, the through holes 12 correspond to an arrangement pattern corresponding to the arrangement position of the electrodes 6 of each semiconductor chip 5 on the workpiece 3. The solder ball 2 has a radius of 50 μm or less, and in accordance with this, each through hole 12 is formed into a circular shape in plan view with an inner diameter slightly larger than the radius of the ball 2. There is.

The frame body 11 is a flat plate body made of materials such as aluminum, 42 alloy, Invar material, SUS430, etc., and is provided with one rectangular opening corresponding to the mask body 10 in the center of the board surface. , one mask body 10 is held by one frame 11. The frame 11 is a molded product that is thicker than the mask body 10, and is inseparably joined to the outer peripheral edge of the mask body 10. Here, the thickness of the frame 11 is, for example, about 0.05 to 1.0 mm, and in this embodiment, it is set to 0.5 mm. Further, the thickness of the mask body 10 is preferably 10 μm or more, and in this embodiment, it is set to 200 μm.

A protrusion 15 projecting downward can be provided on the lower surface side of the mask body 10 (mask 1), that is, on the side facing the workpiece 3. Specifically, as shown in FIGS. 2 and 3, protrusions 15 (crosspieces 15a) can be provided between pattern regions (outer periphery of the pattern regions) so as to surround the pattern regions. The protrusion 15 (crosspiece 15a) does not have to be provided continuously as shown in FIG. 3, but may be provided piecemeal. Furthermore, as shown in FIG. 4, protrusions 15 (pillars 15b) can be provided at positions in the pattern area where through holes 12 are not formed. Further, the shape of the protrusion 15 provided between adjacent pattern areas (outer periphery of the pattern area) so as to surround the pattern area is not limited to the crosspiece 15a, but may be a support 15c as shown in FIG. If such a protrusion 15 is provided, it can come into contact with the upper surface of the workpiece 3 and secure a gap between the mask body 10 and the workpiece 3 during the arrangement operation. As shown in FIGS. 2 and 4, each protrusion 15 (crosspiece 15a, strut 15b) is formed to taper from the lower surface of the mask body 10 toward the tip of the protrusion 15. Preferably, it has a truncated conical shape.

In addition, as shown in FIG. 6, the protrusion 15 may have a shape in which the root size of the protrusion 15 widens toward the lower surface of the mask body 10 (the protrusion 15 narrows from the root toward the tip). It may be a shape that tapers toward the end), and the side surface is formed in an arc shape. This makes it possible to prevent damage caused by stress concentration on the protrusion 15, particularly at the base 15'', and even if the flux 17 adheres to the protrusion 15 when the mask 1 is placed on the workpiece 3. Since the side surface of the protrusion 15 is arcuate, it is possible to prevent the flux 17 from entering the through hole 12, thereby preventing the flux 17 from adhering to the through hole 12, which may lead to poor mounting of the solder ball 2. The end position of the root portion 15'' of the protrusion 15 is preferably located near the through hole 12 on the lower surface of the mask body 10, so that the lower surface 10a of the mask body and the inner surface 12a of the through hole are located close to each other. Possible configurations include a configuration in which the mask is located at the intersection of , and a configuration in which the mask is located at a distance from the through hole 12 on the lower surface 10a of the mask main body. Further, the side surface of the protrusion 15 may be either a convex arc or a concave arc; a convex arc provides good strength, and a concave arc allows the flux 17 to be maintained at any position on the side surface of the protrusion 15. There may be no portion approaching the attached electrode 6, that is, the flux 17 may be kept at a certain distance from the attached electrode 6. Furthermore, the tip 15' and/or the base 15'' of the protrusion 15 may be formed in an arcuate shape, thereby reducing the possibility that the flux 17 will adhere to the protrusion 15 as much as possible.

In the present mask 1, it is preferable that the ratio between the height of the protrusion 15 and the thickness of the mask body 10 is 2:1 or more, and this is satisfied when the thickness of the mask body 10 is in the range of 10 to 300 μm. It is more preferable. Further, the protrusion 15 preferably has a large aspect ratio (the ratio of the height of the protrusion 15 to the tip size), and in this embodiment, the aspect ratio is 3. The root dimension L2 of the protrusion 15 is preferably 1.0 to 1.5 times the tip dimension L1 of the protrusion 15, and is set to 1.2 times in this embodiment. Furthermore, it is preferable that the ratio of the tip dimension L1 of the protrusion 15, the root dimension L2, and the width dimension L3 between the through holes 12 is 1:1.2:1.4 or more. Furthermore, the dimension L4 from the pattern area to the base of the protrusion 15 (crosspiece 15a, support 15c) is preferably set to 0.01 mm or more, and in this embodiment is set to 0.02 mm. Under such conditions, adhesion of flux can be prevented as much as possible. At this time, by satisfying the relationship of the ratio between the tip dimension L1 and the base dimension L2 of the protrusion 15 and the relationship of the dimension L4 from the pattern area to the base of the protrusion 15, damage to the protrusion 15 can be prevented and flux It is possible to achieve both prevention of adhesion. Furthermore, when L5 is the dimension from the pattern area to the center of the tip of the protrusion 15 (crosspiece 15a, pillar 15c), by setting the ratio of L1, L2, and L5 to 1:3:2.5 or more, The above-mentioned coexistence effects can be utilized to the maximum.

Here, the mask 1 is constructed such that the mask body 10 and the protrusions 15 are integrated, but the mask main body 10 and the protrusions 15 may be integrally formed as separate members. In the above-mentioned mask 1, if the mask body 10 is formed of a magnetic material and the projection part 15 is formed of a non-magnetic material, when the mask 1 is fixed to the workpiece 3 by the magnetic attraction of the magnet, the mask 1 can be fixed. Since the magnetic force can be applied uniformly, there is no risk that the mask 1 will be inadvertently bent, and the mask 1 can be brought into close contact with the workpiece, and the alignment accuracy of the through hole 12 with respect to the electrode 6 can be improved. Further, when the mask 1 is removed, the workpiece 3 and the protrusion 15 are not directly magnetically coupled, so that separation of the plates can be improved. Such a mask 1 can be obtained, for example, by forming the mask body 10 from a magnetic metal (nickel, iron, etc.) and forming the protrusion 15 from a non-magnetic metal (copper, aluminum, etc.).

Further, in the case where the protruding portion 15 is formed of a non-magnetic material, it is not limited to the above-mentioned metal, but may be formed of resin or resist. As a result, in addition to the above-mentioned effects, a cushioning effect derived from the elasticity of the resin is exerted, and when the projection 15 comes into contact with the workpiece 3, there is less risk of damage to the workpiece 3. In addition, in order to exhibit such an effect significantly, in the mask 1, it is preferable that not only the protruding portion 15 but also the entire portion that comes into contact with the workpiece 3 is formed of resin. Furthermore, when the projections 15 are formed of resin, they can be formed with high production efficiency by using the same resist as that used when forming the mask body 10 by electroforming.

Furthermore, in the present mask 1, a coating layer 50 is provided on the lower surface of the mask body 10 and the inner surface of the through hole 12, as shown in FIGS. 2, 4, and 6. The coating layer 50 is preferably water repellent, and examples of the material include fluororesin, silicone resin, emulsion, and resist (liquid). By providing such a coating layer 50, even if flux adheres to the lower surface of the mask body 10 or the inner surface of the through hole 12, the flux can be repelled, and the state in which flux remains attached to the lower surface of the mask body 10 or the inner surface of the through hole 12 can be prevented. It can be prevented. The coating layer 50 may be formed on the upper surface of the mask body 10, or may not be formed on the lower surface of the mask body 10 between the pattern areas and between the projections 15 (crosspieces 15a, pillars 15c). . In short, it is desirable to form the solder ball in the part where the solder ball mounting failure is likely to occur if the flux adheres. It is desirable to form this on the surface of the protrusion 15.

Note that each drawing does not show the actual state of the mask 1, but only schematically shows it. Further, the opening dimensions of the through holes 12, the thickness dimensions of the mask body 10, etc. in each drawing are shown as such dimensions for convenience in drawing the drawings. Moreover, in FIGS. 3 and 5, the reference numeral 15 indicates the lower end surface (tip surface) of the protrusion 15, and the root of the protrusion 15 is not illustrated. Further, in FIGS. 3 and 5, the coating layer 50 is not shown.

The operation of arranging the solder balls 2 using the mask 1 is performed in the following procedure. Note that this arrangement work is performed by a dedicated arrangement device (see FIG. 1, FIG. 5, etc. of Patent Document 1). First, a flux 17 (see FIG. 2) is applied by printing onto the electrode 6 of the workpiece 3. Next, the mask 1 is positioned on the workpiece 3 so that the through hole 12 and the electrode 6 are aligned, and then the mask 1 is fixed. This positioning work is actually performed by aligning the outer peripheral edges of the frame 11 and the workpiece 3. When the alignment work is completed, the lower end surface of the protrusion 15 comes into contact with the surface of the workpiece 3 in the fixed state, so that the mask body 10 is aligned with the workpiece 3 as shown in FIGS. 2, 4, and 6. The posture is maintained in a separated posture with a facing gap secured. At this time, it is also possible to arrange a magnet below the workpiece 3 and attract the mask 1 to the workpiece 3 side by the magnetic force of this magnet.

Next, a large number of solder balls 2 are supplied onto the mask 1, the solder balls 2 are dispersed on the mask 1 using a squeegee brush, and the solder balls 2 are introduced into the through holes 12 one by one. In this way, the solder ball 2 is temporarily adhesively held on the electrode 6 by the flux 17. In the operation of inserting solder balls 2 using such a squeegee brush, even if a large squeegee brush pressure is applied to the mask 1, the mask 1 can be prevented from being bent by the protrusion 15, and the operation of inserting the solder balls 2 can be carried out efficiently and smoothly. Can be done.

As described above, since the mask 1 according to the present embodiment includes the protrusion 15 that forms the opposing gap between the mask body 10 and the workpiece 3, the protrusion 15 ensures that the opposing gap with the workpiece 3 is maintained. This makes it possible to efficiently and thoroughly insert the solder balls 2 into the through holes 12.

A reinforcing frame 11 can be provided on the outer periphery of the mask body 10, and if the mask body 10 is formed under tension such that stress in the direction of inward contraction is applied to itself, the surroundings The expansion of the mask body 10 due to temperature changes can be absorbed by the tension in the contraction direction. This can prevent misalignment of the mask body 10 with respect to the workpiece 3. Moreover, since uniform tension can be applied to the entire mask body 10, the solder balls 2 can be mounted on the workpiece 3 with high positional accuracy.

Next, a method for manufacturing the array mask 1 having such a configuration is shown in FIGS. 7 and 8. First, a photoresist layer 31 is formed on the surface of a matrix 30 made of conductive stainless steel or brass steel, for example. This photoresist layer 31 was formed by laminating one or several negative-type photosensitive dry photoresists to a predetermined height and bonding them by thermocompression. Next, as shown in FIG. 7(a), a pattern film (glass mask) 32 having transparent holes 32a corresponding to the projections 15 is tightly attached onto the photoresist layer 31, and then exposed to ultraviolet light using an ultraviolet lamp 33. By performing exposure by irradiating light, performing development and drying processes, and dissolving and removing the unexposed portion, the tapered protrusion 15 is formed as shown in FIG. 7(b). A primary pattern resist 34 having a resist body 34a was formed on the matrix 30. At this time, it is preferable to taper the resist body 34a by using a photoresist through which ultraviolet rays do not easily pass or by weakening the amount of exposure. Next, the mother mold 30 is placed in an electroforming bath prepared under predetermined conditions, and as shown in FIG. A primary electroformed layer 35 was formed by electroforming an electrodeposited metal such as nickel or copper on the surface not covered with the . Here, the primary electroforming layer 35 was formed over substantially the entire surface of the mother mold 30 (first electroforming step). Next, as shown in FIG. 7(d), the primary pattern resist 34 is removed. Here, it is preferable to perform a polishing treatment on the surface of the primary electroformed layer 35.

Next, as shown in FIG. 8(a), a photoresist layer 36 is formed on the entire surface of the primary electroformed layer 35 and the matrix 30, and then the through holes 12 are formed on the surface of the photoresist layer 36. After a pattern film (glass mask) 37 having corresponding transparent holes 37a is closely attached, exposure is performed by irradiating ultraviolet light with an ultraviolet light lamp 33, and the unexposed portions are subjected to development and drying processes. By dissolving and removing, a secondary pattern resist 38 having a resist body 38a corresponding to the mask body 10 was formed on the surface of the primary electroformed layer 35, as shown in FIG. 8(b). Subsequently, it is placed in an electroforming bath prepared under predetermined conditions, and as shown in FIG. A secondary electroformed layer 39 was formed by electroforming an electrodeposited metal such as nickel or copper on the surface of the primary electroformed layer 35 (second electroforming step). Next, the secondary pattern resist 38 is dissolved and removed, and the secondary electroformed layer 39 is peeled off from the matrix 30 and the primary electroformed layer 35. Finally, a coating layer 50 is applied to the matrix surface side of the secondary electroformed layer 39 corresponding to the lower surface of the mask body 10 and to the surface facing the secondary pattern resist 38 of the secondary electroformed layer 39 corresponding to the inner surface of the through hole 12. By forming the mask 1 as shown in FIG. 8(e) and FIG. 2 was obtained.

By attaching the frame 11 to the mask 1 thus obtained, an array mask 1 as shown in FIG. 1 is obtained. The mask 1 (secondary electroformed layer 39) can be held in the frame 11 under tension such that stress in the direction of inward contraction is applied to the mask 1 (secondary electroformed layer 39). To apply such stress, for example, the frame 11 is attached to the outer periphery of the mask 1 in a high temperature environment by utilizing the difference in thermal expansion coefficient between the frame 11 and the mask 1, and the mask 1 is attached at room temperature. This can be achieved by contracting inward.

According to the method for manufacturing the mask 1 as described above, the arraying mask can be manufactured with high accuracy using electroforming, so the solder balls 2 can be mounted on the workpiece 3 with high positional accuracy. Furthermore, if the mask 1 having the protrusions 15 is formed inseparably into the mask body 10 and the protrusions 15 by one electroforming process (second electroforming process), the mask body 10 and the protrusions 15 is formed separately, there is less risk of problems such as breakage of the protrusion 15, and the mask 1 is superior in that it is possible to obtain a highly reliable mask 1 with high accuracy. Furthermore, if the protrusion 15 is formed in a tapered shape that becomes larger as it approaches the lower surface of the mask main body 10, stress concentration in particular at the root of the protrusion 15 can be avoided, thereby increasing the strength of the protrusion 15. While being firmly reinforced, the protrusions 15 can be brought into contact between the electrodes 6 while being separated from the electrodes 6 coated with flux 17, which prevents soldering caused by the flux 17 coated on the electrodes 6 adhering to the mask body 10. It is possible to prevent the ball 2 from being improperly mounted. At this time, it is more effective to set the ratio of the dimension of the tip 15' of the protrusion 15 to the dimension of the base 15'' to be 1:3 or more, and to make the aspect ratio of the protrusion 15 3 or more. Protrusions 15 having such desired dimensions and aspect ratio can be easily produced by adjusting the shape of resist pattern 35.

In addition, in the mask 1 having such a configuration, the shapes of the through holes 12 and the projections 15 may be straight or tapered. Here, to specifically explain the case where the through hole 12 and the protrusion 15 are tapered, the through hole 12 is tapered toward the surface of the mask body 10 facing the workpiece 3. By providing this, it becomes easier to guide the solder ball 2 into the through hole 12, and by providing a tapered shape that widens toward the side of the mask body 10 facing the workpiece 3, the mask body 10 faces the workpiece 3. It is possible to prevent flux from adhering to the periphery of the through hole 12 on the surface side. Furthermore, by providing the protrusion 15 with a tapered shape toward the surface of the mask body 10 facing the workpiece 3, the mask can be securely placed on the workpiece 3. By providing a tapered shape toward the surface of the mask body 10 facing the workpiece 3, the strength of the projections 15 can be ensured even when the electrodes 6 of the workpiece 3 are arranged at a narrow pitch. At the same time, the projection 15 can be firmly brought into contact with the workpiece 3. Such a shape can be easily obtained by changing the photosensitivity and exposure conditions of the photoresist layers 31 and 36.

(Second embodiment)
Next, an array mask according to the second embodiment will be described. In this embodiment, as shown in FIG. 9, the coating layer 50 is formed not only on the lower surface of the mask body 10 but also on the surface of the protrusion 15.

According to the array mask of this embodiment, since the coating layer 50 is also formed on the surface of the protrusion 15, it is possible to prevent flux from adhering to the protrusion 15 as well. Furthermore, by forming the coating layer 50 on the lower surface of the mask body 10, the inner surface of the through hole 12, and the surface of the protrusion 15, even if flux adheres to the inner surface of the through hole 12, the flux is repelled and the lower surface of the mask body 10 and It can flow onto the workpiece via the surface of the protrusion 15. Further, it is possible to more reliably prevent the flux 17 from entering the through hole 12.

Furthermore, by forming the coating layer 50 to cover the entire lower surface of the mask body 10 and the surface of the protrusion 15, for example, when the mask body 10 and the protrusion 15 are formed from separate members, the bonding strength between them can be increased. (This is because as the bumps become finer, the through-hole spacing and pattern area spacing become narrower, and the outer dimensions of the protrusions 15 themselves arranged between the through-holes and between pattern areas (the outer periphery of the pattern area) also become smaller. (This is due to a decrease in the bonding area between the protrusions 15 and the mask body 10), and there is a risk that the protrusions 15 may inadvertently fall off, deform, or be damaged when the mask 1 is used. As a result, the coating layer 50 functions as a protective layer for the protrusion 15, which can also contribute to preventing the protrusion 15 from falling off, deforming, or being damaged. Note that if you want to specifically prevent the protrusions 15 from falling off, deforming, or breaking, a metal layer (Ni, Cu, etc.) may be formed on the lower surface of the mask body 10 and the surface of the protrusions 15 by sputtering or electroless plating. It is preferable to provide the coating layer 50 by doing so.

10 and 11 show a method for manufacturing an array mask of this embodiment. First, as shown in FIG. 10(a), a matrix 40 is prepared. The matrix 40 may be made of any material as long as it has conductivity, and in this embodiment stainless steel is used. Next, a photoresist layer is formed on the surface of the mother mold 40, and the unexposed portions are dissolved and removed by performing exposure, development, and drying processes using well-known methods, as shown in FIG. 10(b). A primary pattern resist 41 having a resist body 41 a was formed on a matrix 40 . The photoresist layer was formed by laminating one or several negative-type photosensitive dry film resists to a predetermined height. Next, the matrix 40 is placed in an electroforming bath prepared under predetermined conditions, and is covered with the resist body 41a of the matrix 40 to the same height as the resist body 41a previously, as shown in FIG. 10(c). Electrodeposited metal was electroformed on the uncoated surface to form a primary electrodeposition layer 42. In this embodiment, the primary electrodeposited layer 42 was formed by Ni--Co electroforming. Note that, after forming the primary electrodeposition layer 42, it is preferable to perform mechanical polishing such as belt polishing and/or electrolytic polishing on the surface of the primary electrodeposition layer 42. Next, as shown in FIG. 10(d), the resist body 41a (resist pattern 41) was dissolved and removed.

Next, as shown in FIG. 11(a), a solder resist layer 43 was formed on the surface of the primary electrodeposition layer 42. This solder resist layer 43 was formed by laminating one or several layers to a predetermined height. Next, by performing exposure, development, and drying treatments to dissolve and remove the unexposed portions, a secondary pattern resist 44 having a resist body 44a is formed on the primary electrodeposited layer 42, as shown in FIG. 11(b). integrally formed. Note that after forming the secondary pattern resist 44, it is preferable to perform a drop-off prevention process such as baking. Thereby, the adhesion between the secondary pattern resist 44 having the resist body 44a and the primary electrodeposited layer 42 can be made stronger. Next, as shown in FIG. 11(c), the primary electrodeposition layer 42 and the secondary pattern resist 44 formed on the surface thereof are peeled off from the matrix 40. Finally, by forming a coating layer 50 on the surface of the primary electrodeposited layer 42 on the side having the secondary pattern resist 44 and on the surface of the secondary pattern resist 44, the array mask shown in FIG. 11(d) and FIG. 1 can be obtained. Note that the coating layer 50 may be formed before the primary electrodeposition layer 42 and the secondary pattern resist 44 are peeled off from the matrix 40. Further, the coating layer 50 is not limited to the surface of the primary electrodeposition layer 42 on the side having the secondary pattern resist 44, but may be formed on the entire surface of the primary electrodeposition layer 42. Of course, the coating layer 50 may also be formed on the inner surface of the through hole 12.

Next, another embodiment of the array mask according to the second embodiment will be described. Here, as shown in FIG. 13(a), the protrusion 15 is made of resin, and a coating layer 70 is formed on the surface of the protrusion 15, and the material of the coating layer 70 is as follows: It is formed of a material different from that of the protrusion 15 .

As mentioned above, this mask is used to mount solder balls onto the electrodes of the workpiece, but dirt may adhere to the mask during the solder ball arranging process (transfer mounting). To remove this, wash the mask as necessary. When cleaning a mask, a solvent is used, so there is a possibility that this solvent may cause negative effects such as stickiness on the surface of the material that makes up the protrusions, but since there is a coating layer on the surface of the protrusions, It protects against such negative effects.

Therefore, in the mask of this embodiment, a coating layer 70 is formed on the surface of the protrusion 15 in order to prevent adverse effects on the protrusion 15 formed of resin, and the coating layer 70 is made of the material that constitutes the protrusion 15. It is made of a material different from (resin). In addition to the above-mentioned materials, the coating layer 70 can also be formed of, for example, a photosensitive material whose main component is acrylic resin.

The method for manufacturing such an array mask is the same as the above-described steps (see FIG. 10) from preparing the matrix to forming the primary electrodeposited layer and removing the resist body. Next, a solder resist layer is formed on the surface of the primary electrodeposited layer 42 and subjected to exposure, development, and drying processes to form a secondary pattern resist having a resist body 60a as shown in FIG. 14(a). 60 was integrally formed on the primary electrodeposition layer 42. Next, as shown in FIG. 14(b), a coating layer 70 is formed on the surface of the secondary pattern resist 60. The coating layer 70 is an alkali-developable photosensitive material, and the main components thereof are acrylic resin (55 to 65%), barium sulfate (15 to 25%), and silicon dioxide (15 to 25%). Finally, by peeling off the primary electrodeposition layer 42 from the matrix 40 together with the secondary pattern resist 60 and coating layer 70 formed on its surface, the arraying mask 1 shown in FIGS. 14(c) and 13 is obtained. Obtainable. Note that the coating layer 70 may also be formed on the surface of the primary electrodeposited layer 42 on the side where the secondary pattern resist 60 is provided. Alternatively, after forming the secondary pattern resist 60 on the primary electrodeposition layer 42 and peeling it off from the matrix 40, the coating layer 70 may be formed. By doing so, the coating layer 70 can be easily formed not only on the surface of the primary electrodeposition layer 42 on the side having the secondary pattern resist 60 but also on the entire surface of the primary electrodeposition layer 42 . The coating layer 70 may also be formed on the inner wall of the through hole 12. Further, after forming the secondary pattern resist 60 and the coating layer 70, it is preferable to perform a drop-off prevention process such as baking. Thereby, the adhesion between the primary electrodeposited layer 42 and the secondary pattern resist 60, and between the secondary pattern resist 60 and the coating layer 70 can be made stronger. Such drop-off prevention treatment may be performed each time the secondary pattern resist 60 and coating layer 70 are formed, or may be performed together after forming the coating layer 70 on the surface of the secondary pattern resist 60.

The mask 1 obtained by such a manufacturing method is resistant to cleaning (solvent), and the occurrence of stickiness on the projections 15 can be prevented as much as possible. Further, as shown in FIG. 13(b), if the coating layer 70 is formed to cover the entire surface of the protrusion 15, breakage and chipping of the protrusion 15 can be prevented.

Here, since the projections 15 and the coating layer 70 are made of the same resin, the adhesion between the projections 15 and the coating layer 70 is strong, but after forming the projections 15 on the mask body 10 (the projections 15 (before forming the coating layer 70 on the surface of the protrusion 15), the protrusion 15 is cleaned to make the surface of the protrusion 15 sticky, and the coating layer 70 is formed on the surface of the protrusion 15. The adhesion with 70 can be made stronger.

Furthermore, as shown in FIG. 13(c), the protrusion 15 can be formed only from the material that forms the coating layer 70. The material forming the coating layer 70 is one to which flux does not easily adhere, and specifically, a resin mixture containing barium sulfate and/or silicon dioxide in an acrylic resin can be mentioned. This resin mixture has excellent solvent resistance. To explain this specifically, such resin mixtures have widths of 0.2 to 3.0 mm (0.2 mm, 0.4 mm, 0.6 mm, 0.8 mm, 1.0 mm, 2.0 mm, 3.0 mm). Each mask, which has protrusions on the mask body made of nickel-cobalt alloy (7 products in total), was soaked in a cleaning agent (manufactured by Kaken Tech Co., Ltd.) for 6 to 24 hours (6 hours, 12 hours, 24 hours total). It was confirmed that there was no peeling of the protrusions in all the masks. Furthermore, since such a resin mixture has good compatibility with the mask body 10 and good adhesion, it is possible to reduce the width dimension of the protrusion 15. In addition, since such a resin mixture has hardness (5H to 6H in the JIS standard scratch hardness test), if the width of the protrusion is made larger than 5 mm when the thickness of the mask body is 100 μm or less, the mask will warp. Therefore, it is preferable that the width of the protrusion is 5 mm or less. In this way, the coating layer 70 is formed mainly of a material such as fluororesin, silicone resin, or acrylic resin. The protrusion 15 can be constructed using such a material as a main component.

The main component of the resin mixture forming the protrusion 15 is acrylic resin, but is not limited to this, and is not limited to polyethylene, polypropylene, polystyrene, polyurethane, polyvinyl chloride, polyvinyl acetate, ABS resin, AS resin, PET resin, EVA resin, fluororesin, polyamide, polyacetal, polycarbonate, polyphenylene ether, polyester, polyolefin, polyphenylene sulfide, polytetrafluoroethylene, polysulfone, polyether sulfone, amorphous polyarylate, liquid crystal polymer, polyether ether ketone, polyimide, Examples include polyamideimide (so-called thermoplastic resin). Further, phenol resin, epoxy resin, melamine resin, urea resin, alkyd resin, polyurethane, etc. (so-called thermosetting resin) may be used.

In each of the above embodiments, the protrusion 15 (post 15b) and the through hole 12 may be arranged so that the protrusion 15 (post 15b) surrounds one through hole 12, or one protrusion 15 may be arranged so that it is surrounded by the through hole 12. When the protrusion 15 is arranged to surround one through hole 12, the shape of the protrusion 15 is not limited to a partial structure like a pillar, but may be an endless frame. Further, the shape of the projection 15 is not limited to the crosspiece 15a or a cylinder, but may be a polygon such as a rhombus or a hexagon, or an ellipse. Furthermore, among these shapes, as shown in FIG. 12, it is preferable to have an elongated shape and/or one with rounded corners. In this way, by aligning the longitudinal direction and major axis direction of these shapes in a certain direction, for example, when cleaning the back side of the mask 1, the cleaning means (cloth, sponge, etc.) can be caught on the protrusion 15. It is possible to eliminate as much as possible the risk of damage to the protrusions 15 and the protrusions 15, and it is also possible to clean them smoothly. Therefore, it is desirable that the longitudinal direction and major diameter direction of all the protrusions 15 are aligned in one direction. Note that the elongated shape is only provided at the lower end surface (tip surface) of the protrusion 15, and the surface of the root portion 15b of the protrusion 15 does not necessarily need to be elongated in terms of strength and the like.

Further, in each of the embodiments described above, the thicknesses of the coating layers 50 and 70 may be made different between the inner surface of the through hole 12 and the surfaces of the mask body 10 and the protruding portions 15. Specifically, when the thickness of the coating layer 50 on the inner surface of the through hole 12 is T1, and the thickness of the coating layer 50 on the surfaces of the mask body 10 and the projections 15 is T2 (see FIG. 9), T1>T2. For example, it is possible to more reliably prevent flux from adhering to the inner surface of the through hole 12, which would cause a solder ball mounting failure. Furthermore, if the coating layer 50 is formed of a material that is slippery (has low friction), a slippery area will appear at the boundary between the top surface of the mask body 10 and the inner surface of the through hole 12 by the thickness of T1, and the thickness of T1 The thicker the solder balls 2, the larger the area, so when brushing the solder balls 2 with a squeegee brush, the squeegee brush and the solder balls 2 can be moved smoothly, and productivity and work efficiency can be expected to improve. If T1<T2, when the protrusion 15 is formed separately on the lower surface of the mask main body 10, falling off, deformation, and damage of the protrusion 15 can be more reliably prevented. Note that there are various methods for forming the coating layer 50, such as a dipping method and a spray method, but when forming the coating layer 50, it is preferable to cover the portion other than the desired formation portion with a protective sheet. In addition, when you want to form the coating layer 50 thickly, you can spray it locally on the parts you want to thicken, or change the direction in which the mask 1 is immersed (for example, if you want to make it thick on the bottom surface of the mask body 10, It is best to immerse the mask in a state where the mask body 10 and the immersion surface are parallel to each other.If you want to make the inner surface of the through hole 12 thicker, it is best to immerse the mask body 10 in a state where the bottom surface of the mask body 10 and the immersion surface are perpendicular to each other.

1 Mask 2 Solder ball 3 Work 6 Electrode 10 Mask body 12 Through hole 15 Protrusion 15a Crosspiece 15b Support 15c Support 15' Tip 15" Root 30, 40 Matrix 31, 36, 43 Photoresist layer (solder resist layer)
34, 41 Primary pattern resist 34a, 41a Resist body 35, 42 Primary electrodeposition layer 38, 44, 60 Secondary pattern resist 38a, 44a Resist body 39 Secondary electrodeposition layer 50, 70 Coating layer

Claims (3)

An arraying mask in which the solder balls (2) are placed at predetermined positions on a workpiece (3) by transferring the solder balls (2) into through holes (12) corresponding to a predetermined array pattern,
comprising a mask body (10) in which the through hole (12) is formed;
An arraying mask characterized in that a coating layer made of fluororesin, silicone resin, emulsion, resist, or acrylic resin is provided on at least the squeegee surface of the mask body (10). The arraying mask according to claim 1, characterized in that a coating layer capable of preventing flux from adhering is provided on a surface of the mask body (10) facing the workpiece (3). A coating layer capable of preventing flux from adhering is provided on the surface of the mask body (10) facing the workpiece (3), and the coating layer is formed of fluororesin, silicone resin, emulsion, resist, or acrylic resin. The arraying mask according to claim 1 or 2, characterized in that:

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