JP2009099963A - Method of forming wiring board having solder bump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wiring board provided with a solder bump, in which a solder ball is difficult to be took off or displaced by a mask for mounting a ball, while the solder bump is formed precisely in a desired position. <P>SOLUTION: In the forming method, a flux F1 is supplied in the whole bump forming region R1 including a plurality of pads 21. The ball mounting mask 51 is prepared when the step of a ball mounting is carried out. The mask 51 has a plurality of openings 54 formed in a position corresponding to the plurality of pads 21, and has a recess 55 in a position corresponding to the bump forming region R1 in the buck side 53 of the mask with occupying a wider region than the bump forming region R1. Then, the solder ball 61 is supplied and disposed on the plurality of pads 21 through the plurality of openings 54 with a mask 51 placed on the substrate main plane 12. After that, the solder bump 62 is formed by heating and melting the solder ball 61. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method of manufacturing a wiring board having solder bumps, and particularly to a method of manufacturing a wiring board in which solder bumps are formed by mounting solder balls using a ball mounting mask.

  Conventionally, a wiring board (so-called semiconductor package) on which an IC chip is mounted is well known. A large number of terminals are usually provided on the bottom surface of the IC chip. As a structure for electrical connection with the terminals, pads having solder bumps on the main surface of the wiring board (so-called C4 pads: ( Many Controlled Collapsed Chip Connection pads) are provided (see, for example, Patent Document 1). Hereinafter, a method for forming solder bumps on the wiring board will be briefly described.

First, flux is printed and applied to a plurality of pads formed in a bump formation region on the main surface of the substrate. Next, a ball mounting mask having a plurality of openings is disposed on the main surface of the substrate, and in this state, solder balls are supplied and mounted on the plurality of pads through the plurality of openings. Next, solder bumps are formed by heating and melting the solder balls by reflow (for example, see Patent Document 1).
JP 2006-73999 A

  However, in the case of the above-described prior art, since the flux with high viscosity is printed and applied immediately before mounting the solder balls, the flux is likely to contact and adhere to the back surface of the mask. In this case, due to the adhesive action of the flux, the solder ball may be carried away to the mask side, or the solder ball may be displaced from the pad, and the solder bump can be accurately formed at the desired position. There was a problem that the occurrence rate of defective products increased. Further, if it is attempted to prevent the solder ball from being removed or misaligned, complicated correction work is required, leading to a reduction in productivity.

  In recent years, with the trend toward miniaturization of electronic components, solder balls are also becoming smaller in diameter. However, in this case, solder balls become lighter, and problems such as removal and misalignment may become more serious. was there.

  Here, it is conceivable to prevent the solder ball from being taken away or misaligned by precisely controlling the flux application position and application amount and accurately applying an appropriate amount of flux only on the pad. However, this method has a certain limit, and leads to a decrease in productivity.

  The present invention has been made in view of the above-described problems, and the object thereof is to prevent solder balls from being removed and misaligned by a ball mounting mask, and to accurately form solder bumps at desired positions. Another object of the present invention is to provide a method for manufacturing a wiring board having solder bumps.

  Means for solving the above problems include a substrate preparation step of preparing a substrate in which a plurality of pads are arranged in a bump formation region on the substrate main surface, and a whole of the bump formation region including the plurality of pads. A flux supply step for supplying flux, a mask surface and a mask back surface, and a plurality of openings that communicate with the mask surface and the mask back surface are formed at positions corresponding to the plurality of pads. Using a ball mounting mask in which a recess that occupies a wider area than the bump forming region is formed at a position corresponding to the bump forming region, and the plurality of ball mounting masks are arranged on the substrate main surface side. A ball mounting step of supplying and mounting solder balls on the plurality of pads through the openings of the substrate, and heating the mounted solder balls Characterized in that it comprises a reflow process of forming solder bumps by fusion, there is a method of manufacturing a wiring board having solder bumps.

  Therefore, according to this means, by providing a concave portion having a predetermined width at a predetermined position of the ball mounting mask, the flux supplied to the entire bump forming area when the mask is disposed in the ball mounting process. It will not contact or adhere to the back side. Therefore, it is difficult for the solder ball to be taken away or misaligned by the mask, and the solder bump can be accurately formed at a desired position. In addition, in the flux supply process, since the method of supplying the flux to the entire bump forming region including a plurality of pads is adopted, compared to the method of accurately supplying the flux only on the plurality of pads, Productivity can be improved.

  A method for manufacturing a wiring board having solder bumps according to the above means will be described below.

  In the substrate preparation step, a substrate in which a plurality of pads are arranged in a bump formation region on the substrate main surface is prepared. The substrate material is not particularly limited and is arbitrary. For example, a resin substrate is preferable. Suitable resin substrates include substrates made of EP resin (epoxy resin), PI resin (polyimide resin), BT resin (bismaleimide-triazine resin), PPE resin (polyphenylene ether resin), and the like. In addition, a substrate made of a composite material of these resins and glass fibers (glass woven fabric or glass nonwoven fabric) may be used. Specific examples thereof include a highly heat-resistant laminate such as a glass-BT composite substrate and a high Tg glass-epoxy composite substrate (FR-4, FR-5, etc.). A substrate made of a composite material of these resins and organic fibers such as polyamide fibers may be used. Alternatively, a substrate made of a resin-resin composite material obtained by impregnating a thermosetting resin such as an epoxy resin with a three-dimensional network fluorine-based resin base material such as continuous porous PTFE may be used. As another substrate material, for example, various ceramics can be selected. The structure of the substrate is not particularly limited. For example, a build-up multilayer wiring substrate having a build-up layer on one side or both sides of the core substrate is preferable.

  The position and number of bump formation regions on the substrate main surface are not particularly limited and are arbitrary. For example, in the case of a so-called multi-cavity substrate, there are bump formation regions corresponding to the number of wiring substrates. Yes. The bump formation region may exist only on one main surface of the substrate, but may also exist on the other main surface.

  The use of the plurality of pads arranged in the bump formation region is not limited. For example, the pads may be pads (so-called C4 pads) for flip-chip connection of IC chips. That is, on the pads for flip chip connection, it is necessary to form small solder bumps for electrical connection with the terminals on the IC chip side having a small size. For this purpose, small diameter solder balls are used. This is because there are many cases.

  The plurality of pads arranged on the main surface of the substrate may be arranged, for example, in a state of being completely exposed on the outermost layer of the main surface of the substrate, but exposed through an opening of a solder resist covering the main surface of the substrate. It is good to be arranged in the state. That is, with this structure, since the pad is positioned at the bottom of the opening of the concave solder resist, the flux is easily held on the pad, and therefore, the solder ball is likely to be temporarily fixed on the pad. Become.

  In the subsequent flux supply process, the flux is supplied to the entire bump forming region including a plurality of pads. In that case, it is preferable to supply the flux as thinly and uniformly as possible to the bump formation region. The method for supplying the flux is not particularly limited, and any method can be adopted. For example, a printing method using a mesh mask is preferable because a thin and uniform flux printing layer can be formed relatively easily. is there. In addition, a flux supply method such as a coating method or a stamp method can be employed.

  The thickness of the flux (if the solder resist is present, the thickness of the flux on it) is appropriately set according to the composition of the flux to be used, the viscosity, etc., in order to prevent adhesion to the back of the mask, For example, it is set to several hundred μm or less so as to be thinner than the depth of the recess.

  The flux supply region may be set to be larger than the bump formation region and smaller than the region occupied by the recess. The reason is as follows. That is, if the supply area of the flux is smaller than the bump formation area, the flux is not sufficiently supplied to the bumps located in the outer periphery of the area, which may increase the defective product generation rate. On the other hand, if the flux supply area is larger than the area occupied by the recesses, the flux adheres to the back surface of the mask, which is not preferable.

  In the subsequent ball mounting process, solder balls are mounted using a ball mounting mask. The ball mounting mask used here has a mask surface and a mask back surface, and a plurality of openings that communicate the mask surface and the mask back surface are formed at positions corresponding to the plurality of pads. In FIG. 4, a recess is formed in a position corresponding to the bump forming area, which occupies an area wider than the bump forming area.

Such a ball mounting mask can be made using any material such as metal, resin, ceramic, etc., but can be made using a metal material such as stainless steel, copper, aluminum, nickel, etc. preferable. The reason is as follows. That is, in the mask having the above-described structure, the portion where the concave portion is formed is thinner than the other portions, so that the strength is originally low, but the strength is further reduced by the formation of the plurality of openings. On the other hand, the mask needs to be formed to be thin and flat to some extent because the handleability and the like are lowered even if it is too thick compared to the diameter of the solder ball to be mounted. In that respect, when a metal material is selected, a predetermined strength can be imparted even when the mask is formed thin.
The deflection amount (mask tension) of the ball mounting mask is not particularly limited and can be arbitrarily set. For example, the deflection amount is preferably 0.17 mm ± 0.01 mm. That is, by setting the amount of bending to such a degree, it becomes difficult for the flux to adhere to the back surface of the mask.

  The plate thickness of the ball mounting mask is not particularly limited, but is preferably slightly larger than the diameter of the solder ball to be mounted. Specifically, it is 5 μm or more and 20 μm or less of the diameter of the solder ball to be mounted. It is preferable. If the thickness is less than 5 μm, depending on the material, sufficient mechanical strength may not be imparted to the mask, and if it exceeds 20 μm, the positioning accuracy of the solder ball may be reduced.

  The method of forming the recesses in the ball mounting mask can be selected as appropriate according to the mask material. For example, when a metal material is selected, half-etching can improve productivity and cost. It is preferable from the viewpoint. In addition to the half etching, it is also possible to adopt a method such as cutting or pressing. The amount of half etching in this case is preferably 30% or more and 70% or less of the mask plate thickness, for example. If it is less than 30%, the recess becomes too shallow, and it becomes difficult to prevent the flux from adhering to the back surface of the mask. On the other hand, if it exceeds 70%, the concave portion becomes deeper as the concave portion becomes deeper, and the mechanical strength may be reduced.

  The plurality of openings in the ball mounting mask are formed so as to communicate the mask front surface and the mask back surface at positions corresponding to the plurality of pads. As a method for forming these openings, any conventionally known method such as etching, drilling, punching, or laser processing can be adopted depending on the mask forming material. The inner diameters of these openings are formed so as to be larger than the diameter of the solder ball to be mounted, for example, the diameter of the solder ball to be mounted is 5 μm to 100 μm. If it is less than 5 μm, it may be difficult to reliably pass the solder ball through the opening. On the other hand, if it exceeds 100 μm, the solder ball can be surely passed through the opening, but it may be difficult to mount the solder ball at a predetermined position. Furthermore, it becomes difficult to apply when a plurality of pads in the bump formation region have a fine pitch.

  As a suitable manufacturing method of the ball mounting mask, for example, a stainless steel plate is selected, and after forming a recess by half-etching the surface on the stainless steel plate on the back side of the mask, a predetermined position of the location where the recess is present And forming a plurality of openings by laser drilling. The advantage of this manufacturing method is that since a hole is made in a thin portion after the formation of the recess, the processing burden at the time of drilling is small, and cost and productivity can be improved. Another advantage is that a plurality of openings having a good shape can be formed with high accuracy compared to the case where the recesses are formed after the drilling process is performed first.

  The size of the solder ball used in the ball mounting process is not particularly limited and can be set as appropriate according to the application of the solder bump to be formed. For example, a fine solder ball having a diameter of 110 μm or less is used. Good. This is because, when a fine solder ball is used, a small solder bump can be formed relatively easily in accordance with the so-called fineness of the C4 pad. In addition, when a small and lightweight solder ball is used, problems peculiar to the present application such as removal by a mask and positional deviation are likely to occur, and therefore, the significance of adopting the above means is great.

  Although it does not specifically limit as a solder material used for a solder ball, For example, a tin lead eutectic solder (Sn / 37Pb: Melting | fusing point 183 degreeC) is used. Sn / Pb solder other than tin-lead eutectic solder, for example, solder having a composition of Sn / 36Pb / 2Ag (melting point 190 ° C.) may be used. In addition to the above lead-containing solder, Sn-Ag solder, Sn-Ag-Cu solder, Sn-Ag-Bi solder, Sn-Ag-Bi-Cu solder, Sn-Zn solder It is also possible to select lead-free solder such as Sn—Zn—Bi solder.

  Then, using such a mask, solder balls are supplied and mounted on the plurality of pads through the plurality of openings in a state where the ball mounting mask is disposed on the substrate main surface side. Then, the solder ball is temporarily fixed on each pad with the adhesive force of the flux.

  In the subsequent reflow process, the solder balls mounted on each pad are heated to a predetermined temperature and melted to form solder bumps having a predetermined shape. Through the above process, a wiring board having solder bumps is manufactured.

  Hereinafter, a method for manufacturing a wiring board according to an embodiment of the present invention will be described in detail with reference to FIGS.

  As shown in FIG. 1, the wiring board 10 of this embodiment is a double-sided build-up multilayer wiring board provided with build-up layers 14 and 15 on both sides. The core substrate 16 constituting the wiring substrate 10 is a substantially rectangular plate-like member in plan view, and through-hole conductors (not shown) are formed at a plurality of locations. These through-hole conductors electrically connect the conductor of the buildup layer 14 on the upper surface side of the core substrate 16 and the conductor of the buildup layer 15 on the lower surface side of the core substrate 16.

  A substantially rectangular bump formation region R1 in a plan view is set on the surface of the buildup layer 14 on the upper surface side (substrate first main surface 12), and the height within the bump formation region R1 is 80 μm to 100 μm. A degree of solder bump 62 is provided. These solder bumps 62 are so-called C4 bumps used for flip-chip connection with terminals on the IC chip 71 side. On the other hand, a bump formation region is also set on the surface of the buildup layer 15 on the lower surface side (substrate second main surface 13), and a solder bump 63 having a height of about 400 μm to 600 μm is provided in the bump formation region. It has been. These solder bumps 63 are so-called BGA bumps that are used for electrical connection with a motherboard-side terminal (not shown).

  Since both the build-up layers 14 and 15 in the wiring board 10 of the present embodiment have the same structure, only the top-side build-up layer 14 will be described in detail here. As shown in FIG. 7, the buildup layer 14 is formed by alternately laminating interlayer insulating layers 31 and 32 and copper plating conductor layers 43 and 44. A plurality of pads 21 are formed on the interlayer insulating layer 32. The interlayer insulating layer 32 is entirely covered with a solder resist 33. A plurality of openings 22 are formed in the solder resist 33 corresponding to the positions of the plurality of pads 21. Each of the interlayer insulating layers 31 and 32 has a thickness of about 30 μm, and is made of, for example, a resin-resin composite material obtained by impregnating continuous porous PTFE with an epoxy resin. Filled via conductors 41 and 42 made of copper plating are provided at predetermined positions in the interlayer insulating layers 31 and 32, respectively. The filled via conductor 41 is electrically connected to the conductor layers 43 and 44. The filled via conductor 42 conducts the conductor layer 44 and the pad 21.

  Next, a method for manufacturing the wiring board 10 of the present embodiment having the solder bumps 62 and 63 will be described.

  First, as shown in FIG. 2, a substrate 11 is prepared in which a plurality of pads 21 are arranged in a bump formation region R1 on the first substrate main surface 12 (substrate preparation step). At this stage, each pad 21 is exposed through each opening 22 in the solder resist 33.

  In the subsequent flux supply step, the substrate 11 is set in a conventionally known printing apparatus (not shown), and printing using a mesh mask is performed, whereby the flux F1 is thinly and uniformly applied to the substrate first main surface 12 side ( (See FIG. 3). At this time, the flux F1 is applied to the entire region (flux F1 supply region R2) that is slightly larger than the bump forming region R1 including the plurality of pads 21. However, the supply area R2 of the flux F1 is set to be smaller than the occupation area R3 of the recess 55 of the ball mounting mask 51 described later (see FIGS. 4 and 5). More specifically, in the present embodiment, a region that is approximately 0.5 mm larger than the outline of the bump forming region R1 is used as the supply region R2 of the flux F1, and the flux F1 is solidly applied to the entire region.

  In the subsequent ball mounting process, the solder balls 61 are mounted using the ball mounting mask 51 shown in FIG. In the present embodiment, as a solder ball 61 to be mounted, a fine solder ball having a diameter of about 100 μm is used. This ball mounting mask 51 is made of a stainless steel plate having a mask surface 52 and a mask back surface 53 and having a plate thickness of about 110 μm. Here, the plate thickness of the mask 51 is set to be about 10 μm larger than the diameter (100 μm) of the solder ball 61 to be mounted. In the mask 51, a plurality of openings 54 that communicate the mask front surface 52 and the mask back surface 53 are formed at positions corresponding to the plurality of pads 21. The plurality of openings 54 are circular holes in plan view, and the inner diameter thereof is about several tens of micrometers larger than the diameter (100 μm) of the solder ball 61 to be mounted, and is about 130 μm to 170 μm. Further, a rectangular recess 55 that occupies a region (occupied region R3 of the recess 55) slightly larger than the bump formation region R1 in plan view is formed at a position corresponding to the bump formation region R1 on the mask back surface 53 side. ing. Specifically, in this embodiment, an area that is approximately 0.5 mm larger than the outline of the supply area R2 of the flux F1 is set as the occupation area R3 of the recess 55. The depth of the recess 55 is 55 μm and is set to be 50% of the mask plate thickness. In addition, the thickness of the thin part corresponding to the position of the recessed part 55 is 55 micrometers.

  The ball mounting mask 51 used in this embodiment forms a recess 55 by half-etching the surface of the stainless steel plate on the mask back surface 53 side, and then laser drills a predetermined position where the recess 55 is located. It is manufactured by a procedure in which a plurality of openings 54 are formed by processing. According to this manufacturing method, since the hole for forming the opening 54 is drilled in the thin portion after the recess 55 is formed, the processing burden at the time of drilling is small, and the cost and productivity are improved. be able to. In addition, the plurality of openings 54 having a good shape can be formed with high accuracy as compared with the case where the recess 55 is formed after the previous drilling process. In addition, by selecting optical processing instead of mechanical processing, a large number of fine holes can be formed efficiently.

  Next, as shown in FIG. 6, the concave surface 55 is made to face the supply region R <b> 2 of the flux F <b> 1, and the mask back surface 53 side of the ball mounting mask 51 is the solder resist 33 on the substrate first main surface 12 side. Place it in close contact with the surface. At this time, since a gap is formed between the inner bottom surface of the recess 55 and the surface of the solder resist 33, a situation in which the flux F1 contacts and adheres to the mask back surface 53 side is avoided. In such a mask arrangement state, a large number of fine solder balls having a diameter of about 100 μm as the solder balls 61 are supplied to the mask surface 52 side of the ball mounting mask 51. Then, the solder balls 61 fall into the plurality of openings 54 and are placed on the pads 21 immediately below the openings 54, and are temporarily fixed to the pads 21 with the adhesive force of the flux F1. That is, through this step, the plurality of solder balls 61 are supplied and mounted on the plurality of pads 21 through the plurality of openings 54.

  In the subsequent reflow process, the substrate 11 is set in a conventionally known reflow furnace, and each solder ball 61 mounted on each pad 21 is heated to a predetermined temperature and melted. As a result, a solder bump 62 having a predetermined shape as shown in FIG. 7 is formed. In addition, although detailed description is abbreviate | omitted, formation of the solder bump 63 in the board | substrate 2nd main surface 13 side is also performed based on this. Through the above process, the wiring substrate 10 having the solder bumps 62 is manufactured.

  Therefore, according to the present embodiment, the following effects can be obtained.

  (1) In this embodiment, a concave portion 55 that occupies a region larger than the bump formation region R1 and smaller than the occupation region R3 of the concave portion 55 is provided at a predetermined position on the mask back surface 53 side of the ball mounting mask 51. . Therefore, when the mask 51 is arranged on the substrate first main surface 12 side in the ball mounting process, the flux F1 supplied to the entire bump forming region R1 does not contact and adhere to the mask back surface 53. Therefore, it becomes difficult for the solder balls 61 to be taken away or misaligned by the mask 51, and the solder bumps 62 can be accurately formed at desired positions, and the defective product generation rate can be reduced.

  (2) In this embodiment, a method is adopted in which the flux F1 is supplied by so-called solid coating to the entire bump forming region R1 including the plurality of pads 21 in the flux supply step. Therefore, unlike the method of accurately supplying the flux F1 only on the plurality of pads 21, it is not necessary to finely control the application position and application amount of the flux F1, and the productivity can be improved. Further, complicated correction work for preventing the solder ball 61 from being taken away or misaligned becomes unnecessary, which also contributes to improvement in productivity.

  In addition, you may change embodiment of this invention as follows.

  In the above embodiment, the present invention is embodied in the double-sided build-up multilayer wiring board having the build-up layers 14 and 15 on both sides, but is embodied in the single-sided build-up multilayer wiring board having the build-up layer 14 on only one side. Also good. Alternatively, it may be embodied in a multilayer wiring board of a type that does not include a buildup layer.

  In the above embodiment, the flux F1 is supplied by using a printing method using a mesh mask. However, a printing method using a flux printing mask other than the mesh mask, a printing method not using this type of mask, and the like. Or a method other than the printing method may be employed.

  In the above embodiment, a small solder ball having a diameter of about 100 μm is used as the solder ball 61 to be mounted. However, for example, a relatively large solder ball having a diameter of about 300 μm to 500 μm can be used.

  In the above embodiment, the concave portion 55 of the ball mounting mask 51 is formed by half-etching, but this may be formed by cutting or the like. Moreover, in the said embodiment, although the several opening part 54 in the said mask 51 was formed by laser drilling, you may form them by drilling etc.

  In the above embodiment, the ball mounting mask 51 is formed of a metal material, but may be formed of a resin material, for example. In this case, you may make it form the recessed part 55 and the some opening part 54 simultaneously at the time of metal mold | die shaping | molding.

  In the above embodiment, the plurality of pads 21 included in the wiring board 10 are pads for flip chip connection of the IC chip 71, but flip chip connection of electronic components other than the IC chip 71 and another wiring board is possible. It may be a pad.

1 is a schematic view of a wiring board having solder bumps according to an embodiment of the present invention. The principal part expanded sectional view for demonstrating the manufacturing method of the said wiring board. The principal part expanded sectional view for demonstrating the manufacturing method of the said wiring board. The principal part expanded sectional view for demonstrating the manufacturing method of the said wiring board. The principal part enlarged plan view for demonstrating the manufacturing method of the said wiring board. The principal part expanded sectional view for demonstrating the manufacturing method of the said wiring board. The principal part expanded sectional view for demonstrating the manufacturing method of the said wiring board.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Wiring board which has solder bump 11 ... Board | substrate 12 ... Board | substrate 1st main surface as a board | substrate main surface 21 ... Several pads 22 ... Solder resist opening 33 ... Solder resist 51 ... Mask for ball mounting 52 ... Mask surface 53 ... Mask back surface 54 ... Multiple openings 55 ... Recess 61 ... Solder ball 62 ... Solder bump 71 ... IC chip F1 ... Flux R1 ... Bump formation area R2 ... Flux supply area R3 ... Recessed area

Claims (9)

A substrate preparation step of preparing a substrate in which a plurality of pads are arranged in a bump formation region on the substrate main surface;
A flux supplying step for supplying a flux to the entire bump forming region including the plurality of pads;
A plurality of openings that have a mask surface and a mask back surface and that communicate with the mask surface and the mask back surface are formed at positions corresponding to the plurality of pads, and are located at positions corresponding to the bump formation regions on the mask back surface side. Using a ball mounting mask formed with a recess that occupies a wider area than the bump forming region, the ball mounting mask is disposed on the substrate main surface side, and the plurality of openings are disposed through the plurality of openings. A ball mounting process for supplying and mounting solder balls on the pads;
And a reflow step of forming solder bumps by heating and melting the mounted solder balls. A method of manufacturing a wiring board having solder bumps.   2. The method of manufacturing a wiring board having solder bumps according to claim 1, wherein the supply region of the flux is set to be larger than the bump formation region and smaller than the region occupied by the recess. Method.   The said recessed part in the said mask for ball mounting is a recessed part formed by half etching, The amount of the said half etching is 30% or more and 70% or less of a mask board thickness, The Claim 1 or 2 characterized by the above-mentioned. A method of manufacturing a wiring board having solder bumps.   4. The solder bump according to claim 1, wherein the main surface of the substrate is covered with a solder resist, and the plurality of pads are exposed through openings of the solder resist. 5. A method of manufacturing a wiring board having   5. The solder bump according to claim 1, wherein the ball mounting mask is a stainless steel plate having a mask plate thickness of 5 μm or more and 20 μm or less of a diameter of a solder ball to be mounted. A method for manufacturing a wiring board.   The ball mounting mask has a plurality of openings formed by laser-etching a predetermined position where the recess is present after half-etching the surface on the back side of the mask in the stainless steel plate to form the recess. 6. The method of manufacturing a wiring board having solder bumps according to claim 5, wherein the wiring board is manufactured by forming a portion.   7. The method of manufacturing a wiring board having solder bumps according to claim 1, wherein the plurality of pads are pads for flip-chip connection of IC chips.   The method of manufacturing a wiring board having solder bumps according to claim 7, wherein the solder balls are minute solder balls having a diameter of 110 μm or less.   9. The method of manufacturing a wiring board having solder bumps according to claim 1, wherein the deflection amount of the ball mounting mask is 0.17 mm ± 0.01 mm.

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