KR20110103876A - Method of forming wiring board having solder bump, and solder ball mounting mask - Google Patents

Abstract

DISCLOSURE OF THE INVENTION An object of the present invention is to provide a method for manufacturing a wiring board having solder bumps which can improve the production yield by preventing the occurrence of double balls or the like and accurately forming solder bumps at a desired position.
(Solution means) The wiring board is manufactured through a substrate preparation step, a ball mounting step, and a reflow step. In the substrate preparation step, the substrate 11 having the pads 21 arranged in the bump forming region R1 on the substrate main surface 13 is prepared. In the ball mounting step, a solder ball mounting mask 51 having a recess 59 formed therein to avoid contact with the edge portion 12 of the substrate 11 is used, and the solder ball mounting mask 51 is used as a substrate main surface ( The solder ball 61 is mounted on the pad 21 through the through hole 54 in the state where it is arranged on the 13) side. In the reflow step, the solder balls 61 are heated and melted to form solder bumps 62.

Description

Manufacturing method of wiring board which has solder bump and solder ball mounting mask {METHOD OF FORMING WIRING BOARD HAVING SOLDER BUMP, AND SOLDER BALL MOUNTING MASK}

The present invention relates to a method for manufacturing a wiring board for forming solder bumps by mounting solder balls, and to a solder ball mounting mask used for mounting solder balls.

Conventionally, a wiring board (so-called semiconductor package) formed by mounting an IC chip is well known. The bottom surface of the IC chip is usually formed with a plurality of terminals, and is a structure for electrical connection with these terminals, and has a pad having solder bumps on the main surface of the wiring board (so-called C4 pad: Controlled Collapsed Chip). Many connection pads) are formed. Moreover, as a method of forming a solder bump in the said wiring board, it is proposed to heat-melt the solder ball mounted on the pad, for example, and to form a solder bump (for example, refer patent document 1). Hereinafter, the specific example of the formation method of a solder bump is briefly demonstrated based on FIG.

First, flux is applied to the plurality of pads 102 formed in the bump forming region R0 on the substrate main surface 101. Subsequently, the solder ball mounting mask 104 having the plurality of openings 103 is disposed on the substrate main surface 101, and in this state, the solder balls (not shown) are mounted on the plurality of pads 102 through the openings 103. 105) is supplied and mounted (see, for example, Patent Document 1). Subsequently, solder bumps are formed by heating and melting the solder balls 105 by reflow.

Patent Document 1: Japanese Patent Application Laid-Open No. 2002-151539 (Fig. 1, etc.)

By the way, the edge part 106 of the board | substrate 100 may roll up to the mask back surface 107 side. In this case, since a part of the solder ball mounting mask 104 is lifted by the edge portion 106 and is lifted up, a gap is formed between the solder ball mounting mask 104 and the substrate 100. As a result, the situation where two solder balls 105 are inserted into one opening 103 and the position of the solder balls 105 is displaced on the pad 102 is likely to occur (so-called double balls). You lose. Therefore, since solder bumps cannot be formed correctly in a desired position, there exists a problem that the inferior goods incidence becomes large and a manufacturing yield falls.

Also, in recent years, the solder balls 105 tend to be miniaturized in accordance with the trend of miniaturization of electronic components. In this case, the plurality of solder balls 105 is easily inserted into the openings 103. . Therefore, there exists a possibility that the problem of the position shift of the solder ball 105 resulting from generation | occurrence | production of a double ball etc. becomes more serious.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and its object is to manufacture a wiring board having solder bumps which can improve the manufacturing yield by preventing the occurrence of double balls or the like and accurately forming solder bumps at desired positions. To provide a method. Moreover, another object is to provide the solder ball mounting mask which is suitable for formation of a solder bump.

Means for solving the above problems (first means) include: a substrate preparation step of preparing a substrate on which a plurality of pads are arranged in a bump forming region on a substrate main surface; A through hole portion having a mask surface and a mask back surface and penetrating the mask surface and the mask back surface is formed at a position corresponding to the plurality of pads, and is an outer region of the through hole portion and the bump formation on the mask back surface side. A pressing portion for pressing the substrate in contact with the main surface of the substrate is formed at a position corresponding to the outer region of the region, and is an outer region of the pressing portion, and the edge portion at a position corresponding to an edge portion of the substrate on the mask back surface side. Using a solder ball mounting mask having a recessed portion to avoid contact with the solder ball, and supplying solder balls onto the plurality of pads through the through-holes with the solder ball mounting mask disposed on the main surface side of the substrate; A ball mounting step for mounting; And a reflow step of forming a solder bump by heating and melting the mounted solder ball.

Therefore, according to the first means, since the solder ball mounting mask having the recessed portion that avoids contact with the edge portion of the substrate is used, even if the edge portion is rolled up toward the mask back side, the edge portion does not contact the back side of the mask without being recessed. It will be accommodated in the department. As a result, lifting of the mask for mounting a solder ball due to being pushed by the edge part is prevented, and it becomes difficult to produce a gap between the mask for mounting a solder ball and a board | substrate. Therefore, the position shift of the solder balls due to the occurrence of the double balls is less likely to occur, and the solder bumps can be accurately formed at a desired position. Therefore, the incidence of defective products is suppressed low and the production yield of the wiring board to be manufactured is increased. do.

Hereinafter, the manufacturing method of the wiring board which has the solder bump which concerns on the said 1st means is demonstrated.

In the substrate preparation step, a substrate in which a plurality of pads are arranged in a bump forming region on a substrate main surface is prepared. Although the board | substrate material is not specifically limited and arbitrary, For example, a resin substrate etc. are optimal. As a suitable resin substrate, the board | substrate which consists of EP resin (epoxy resin), PI resin (polyimide resin), BT resin (bismaleade-triazine resin), PPE resin (polyphenylene ether resin), etc. are mentioned. In addition, you may use the board | substrate which consists of a composite material of these resin and glass fiber (glass woven fabric or glass nonwoven fabric). Specific examples thereof include high heat-resistant laminates such as glass-BT composite substrates and high Tg glass-epoxy composite substrates (FR-4, FR-5, etc.). Moreover, you may use the board | substrate which consists of composite materials of these resins and organic fiber, such as a polyamide fiber. Alternatively, a substrate made of a resin-resin composite material impregnated with a three-dimensional network fluorine resin base material such as continuous porous PTFE and a thermosetting resin such as epoxy resin may be used. As another substrate material, various ceramics etc. can also be selected, for example. The structure of the substrate is not particularly limited. For example, a buildup multilayer wiring board having a buildup layer on one or both surfaces of the core substrate is optimal.

The position and number of bump forming regions on the main surface of the substrate are not particularly limited and arbitrary. For example, in the case of a so-called multiple patterning board, there are bump forming regions corresponding to the number of patterns of the wiring board. Doing. The bump forming region may exist only on one main surface of the substrate, but may also exist on the other main surface.

Although the use is not limited about the some pad arrange | positioned in a bump formation area, For example, it is good that it is a pad for flip chip connection of an IC chip (so-called C4 pad). That is, on the pad for flip chip connection, it is necessary to form a small solder bump in order to achieve electrical connection with the terminal of a small IC chip, and therefore, solder balls of small diameter are often used.

Next, in a ball mounting process, a solder ball is mounted using the solder ball mounting mask. The solder ball mounting mask used herein has a mask surface and a mask back surface, and a through hole portion penetrating the mask surface and the mask back surface is formed at a position corresponding to a plurality of pads, and is an outer region of the through hole portion and on the mask back surface side. A pressing portion for contacting the substrate main surface and pressing the substrate at a position corresponding to the outer region of the bump forming region is formed, the outer portion of the pressing portion and a contact with the edge portion at a position corresponding to the edge portion of the substrate on the mask back surface side. It has the structure in which the recessed part which avoids is formed.

Such a solder ball mounting mask can be produced using any material such as metal, resin, ceramic, etc., but is preferably produced using metal materials such as stainless steel, copper, aluminum and nickel. The reason for this is as follows. That is, in the solder ball mounting mask, the portion where the through-hole portion is formed has a lower strength than other portions. On the other hand, if the solder ball mounting mask is too thick compared to the diameter of the solder ball to be mounted, it causes deterioration in handling and the like. This is because, when a metal material is selected, a predetermined strength can be given even when the mask for solder ball mounting is formed thin.

The mask plate thickness of the solder ball mounting mask is not particularly limited, but it is preferable to have a mask plate thickness slightly larger than the diameter of the solder ball to be mounted, and specifically 5 µm or more and 20 µm or less than the diameter of the solder ball to be mounted. It is preferable that it is a board | plate material which has a mask plate thickness as large as it is. If it is less than 5 micrometers, there exists a possibility that sufficient mechanical strength may not be provided to a solder ball mounting mask depending on a material. On the other hand, if it is 20 micrometers or more, there exists a possibility that the positioning precision of a solder ball may fall.

The through-hole portion is preferably constituted by a mask surface side opening that is opened at the mask surface and a mask back side opening that is opened at the mask back surface. In this case, when the occupied area of the mask backside opening is larger than the bump forming area, the flux is supplied to the entire bump forming area, and the flux is in contact with the back of the mask even if the solder ball mounting mask is arranged in the ball mounting process. It will not be attached. Therefore, sticking and position shift of a solder ball by a solder ball mounting mask hardly arise, and a solder bump can be correctly formed in a desired position.

Moreover, it is preferable that the through-hole part has a some mask surface side opening part, and the some mask surface side opening part is opened in the inner bottom face of the mask back side opening part. In this case, it is possible to set one solder ball to be inserted into each of the mask surface side openings. Therefore, even if the occupation area of the mask back side opening is made larger than the occupation area of the mask surface side opening, the solder ball is reliably positioned. It can be mounted. Therefore, since solder bumps can be formed correctly in a desired position, the inferior product incidence rate will become low and manufacture yield will improve. Here, as the method for forming the mask surface side openings, conventionally known methods such as etching, drilling, punching, and laser processing can be arbitrarily adopted depending on the mask forming material. The inner diameter of the mask surface side opening is formed to be larger than the diameter of the solder ball to be mounted, and is preferably formed to be 5 µm or more and 100 µm or less than the diameter of the solder ball to be mounted. If it is less than 5 µm, it may be difficult to reliably pass the solder ball through the mask surface side opening. On the other hand, if it is 100 micrometers or more, a solder ball can reliably pass through a mask surface side opening part, but there exists a possibility that a solder ball may become difficult to mount in a predetermined position. In addition, it is difficult to apply when a plurality of pads in the bump forming region have a fine pitch.

The recessed portion is an outer region of the pressing portion and is opened at a position corresponding to the edge portion of the substrate on the mask back side. In addition, the recess is preferably a groove portion formed along the edge portion. In this case, since the area in which the recess is opened on the back surface of the mask can be made small, the decrease in strength of the solder ball mounting mask when the recess is formed can be minimized.

The method of forming a mask back side opening part and a recessed part in the solder ball mounting mask can be suitably selected according to a mask material. For example, when a metal material is selected, it is optimal from the viewpoint of productivity and costability that the mask back side opening portion and the concave portion are simultaneously formed by half etching and have the same depth. In addition to half etching, a method such as cutting or pressing may also be employed.

In addition, as an optimal manufacturing method of a solder ball mounting mask, a stainless steel plate is selected, for example, and the surface used as the mask back surface side is half-etched in the said stainless steel plate, and the opening part and the recessed part of a mask back surface side are formed simultaneously. Thereafter, laser punching is performed at a predetermined position where the mask back side opening part is provided to form a plurality of mask surface side opening parts. The advantage of this manufacturing method is that punching is performed on the location where the thickness is thin after forming the mask back side opening, so that the processing load during punching is small, and the cost and productivity can be improved. Another advantage is that a plurality of mask surface side openings having a good shape can be formed with high precision as compared with the case where the mask back side openings are formed after punching is performed first.

The size of the solder balls used in the ball mounting step is not particularly limited and can be appropriately set according to the use of the solder bumps to be formed. For example, micro balls having a diameter of 200 μm or less are preferably used. It is because a small solder bump can be formed relatively easily corresponding to the so-called C4 pad pinning when a micro ball is used. In addition, when a microscopic and lightweight solder ball is used, a problem peculiar to the present invention of the occurrence of so-called double ball is likely to occur, and therefore the significance of employing 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 process solder (Sn / 37Pb: melting | fusing point 183 degreeC) is used. Sn / Pb-based solder other than tin lead eutectic solder, for example, a solder (melting point 190 ° C.) having a composition of Sn / 36Pb / 2Ag may be used. In addition to the above-described lead-containing solder, Sn-Ag solder, Sn-Ag-Cu solder, Sn-Ag-Bi solder, Sn-Ag-Bi-Cu solder, Sn-Zn solder, and Sn- It is also possible to select lead-free solder such as Zn-Bi solder.

And while using the said solder ball mounting mask, a solder ball is supplied to several pads through a through-hole part (plural mask surface side openings) in the state which arrange | positioned the said solder ball mounting mask to the board | substrate main surface side. And also mounted.

Subsequently, in a reflow process, the solder ball mounted on each pad is heated and melt | dissolved to predetermined temperature, and the solder bump of a predetermined shape is formed. Through the above process, a wiring board having solder bumps is manufactured.

As another means (second means) for solving the above problems, a mask having a mask surface and a mask back surface is formed, and a through hole portion penetrating the mask surface and the mask back surface is formed and is disposed on the substrate main surface side of the substrate. A solder ball mounting mask which supplies and mounts solder balls onto the main surface of the substrate through a plurality of through holes, wherein the substrate is pressed against the main surface of the mask in the outer region of the through hole to press the substrate. There is a mask for mounting a solder ball, wherein a pressing portion is formed, and a recess is formed on the mask back side in the outer region of the pressing portion to avoid contact with an edge portion of the substrate.

Therefore, according to the second means, since the recess for avoiding contact with the edge of the substrate is formed in the mask for solder ball mounting, when the edge of the substrate is rolled up to the mask back side, the mask for solder ball mounting is used as the substrate. Even if arranged on the main surface side, the edge portion is accommodated in the concave portion without contacting the mask back surface. As a result, lifting of the mask for mounting a solder ball due to being pushed by the edge part is prevented, and it becomes difficult to produce a gap between the mask for mounting a solder ball and a board | substrate. Therefore, since the shift | offset | difference of the solder ball resulting from generation | occurrence | production of a double ball etc. hardly occurs, it becomes a mask for mounting a solder ball which is optimal for formation of a solder bump.

1 is a schematic view of a wiring board having solder bumps of this embodiment
2 is a sectional view of principal parts for explaining a method for manufacturing a wiring board.
3 is a sectional view of principal parts for explaining a method for manufacturing a wiring board.
4 is an enlarged cross-sectional view showing main parts for explaining a method of manufacturing a wiring board;
5 is a plan view of principal parts for explaining a method of manufacturing a wiring board;
6 is an enlarged cross-sectional view of main parts for explaining a method of manufacturing a wiring board;
7 is a sectional view of principal parts for explaining a method for manufacturing a wiring board.
8 is an enlarged cross-sectional view of a main portion for explaining a method for manufacturing a wiring board in another embodiment;
9 is an enlarged cross-sectional view of a main portion for explaining a method for manufacturing a wiring board in another embodiment;
10 is an enlarged cross-sectional view of a main portion showing a problem of the prior art;

EMBODIMENT OF THE INVENTION Hereinafter, the manufacturing method of the wiring board of one Embodiment which embodied this invention is demonstrated in detail based on FIG.

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 15 and 16 on both sides. The core substrate 17 constituting the wiring board 10 is a substantially rectangular plate-like member in plan view, and through hole conductors (not shown) are formed in a plurality of places. These through-hole conductors electrically connect the conductors of the buildup layer 15 on the upper surface side of the core substrate 17 and the conductors of the buildup layer 16 on the lower surface side of the core substrate 17.

On the surface of the build-up layer 15 (the first substrate main surface 13), a bump forming region R1 having a substantially rectangular shape (viewed from the plane) is set, and within this bump forming region R1, the height is 80 占 퐉. Plural solder bumps 62 having a thickness of ˜100 μm are arranged. These solder bumps 62 are so-called C4 bumps used for flip chip connection with the terminals of the IC chip 71. On the other hand, bump formation regions (not shown) are also set on the surface of the build-up layer 16 (the second substrate main surface 14), and solder bumps 63 having a height of about 400 µm to 600 µm are formed in the bump formation region. ) Are formed in plural. These solder bumps 63 are so-called BGA bumps used for electrical connection with terminals not shown on the motherboard side.

Since the buildup layers 15 and 16 of this embodiment have the same structure, only the buildup layer 15 on the upper surface side will be described in detail here. As shown in FIG. 7, the buildup layer 15 is formed by alternately stacking the interlayer insulating layers 31 and 32 and the copper plating conductor layers 43 and 44. The interlayer insulating layers 31 and 32 each have a thickness of about 30 mu m, and are made of, for example, a resin-resin composite material impregnated with epoxy resin in continuous porous PTFE. Moreover, the some pad 21 is arrange | positioned at the surface of the interlayer insulation layer 32 used as a 2nd layer in an array shape. The surface of the interlayer insulating layer 32 is almost entirely covered by the solder resist 33. The solder resist 33 is formed with an opening 22 exposing each pad 21. Further, field via conductors 41 and 42 made of copper plating are formed at predetermined positions in the interlayer insulating layers 31 and 32, respectively. The field via conductors 41 and 42 electrically connect the pads 21 and the copper plating conductor layers 43 and 44 with each other.

Next, the manufacturing method of the wiring board 10 which has solder bumps 62 and 63 is demonstrated.

First, in the substrate preparation process, the board | substrate 11 in which the some pad 21 was arrange | positioned in the bump formation area R1 on the 1st board | substrate main surface 13 is prepared (refer FIG. 2). In addition, in this step, each pad 21 is exposed in each opening part 22 of the soldering resist 33.

Subsequently, in the flux supply process, the substrate 11 is set in a conventionally known printing apparatus (not shown), and the flux F1 is applied to the first substrate main surface 13 side thinly and uniformly by printing using a mesh mask. (See Figure 3). At this time, the flux F1 is applied to the entire flux supply region R2 that is larger than the bump forming region R1.

Next, in the ball mounting process, the solder ball 61 is mounted using the mask 51 for solder ball mounting (refer FIG. 4). In the present embodiment, a micro ball having a diameter of about 100 μm is used as the solder ball 61. The solder ball mounting mask 51 is made of a stainless steel plate having a mask surface 52 and a mask back surface 53. The solder ball mounting mask 51 is a plate having a mask plate thickness (110 μm) that is about 10 μm larger than the diameter of the solder ball 61 to be mounted. In addition, the mask surface 52 and the mask back surface 53 are flat surfaces which do not have a protrusion part. And the through-hole part 54 which penetrates the mask surface 52 and the mask back surface 53 is formed in the position corresponding to each pad 21 in the solder ball mounting mask 51. As shown in FIG. The through hole portion 54 is constituted by a plurality of mask surface side openings 55 opening in the mask surface 52 and one mask back side opening opening 56 opening in the mask back surface 53. Each mask surface side opening 55 is not only opened in the mask surface 52 but also opened in the inner bottom 57 of the mask back side opening 56, and occupies much smaller area than the bump forming region R1 ( It is a through-hole of circular shape (viewed from the plane) which has R3) (refer FIG. 4, FIG. 5). Each mask surface side opening part 55 has an inner diameter (about 130 micrometers-about 170 micrometers) which is about tens of micrometers larger than the diameter of the solder ball 61 to mount. Moreover, each mask surface side opening part 55 is set to the depth (55 micrometer) of 50% of the thickness of a mask plate. On the other hand, the mask back side opening portion 56 is formed at a position corresponding to the bump formation region R1 on the mask back surface 53 side and has a rectangular shape having an occupied region R4 slightly wider than the flux supply region R2. It is a through hole (as seen from the plane) (refer FIG. 4, FIG. 5). Therefore, the occupied region R4 of the mask back side opening 56 is larger than the occupied region R3 of the mask surface side opening 55. In addition, the mask back side opening part 56 is set to the depth (55 micrometer) of 50% of the thickness of a mask plate.

As shown in FIG. 4 and FIG. 5, the area | region corresponding to the outer side of bump formation area | region R1 (and flux supply area | region R2) in the mask back surface 53 side in the outer area | region of the through-hole part 54 is shown. The press part 58 is formed in the position. The pressing portion 58 is set to the same thickness as the mask plate, and has a function of pressing the substrate 11 in contact with the first substrate main surface 13. In addition, at the position corresponding to the edge portion 12 of the substrate 11 on the mask back surface 53 side in the outer region of the pressing portion 58, a groove portion (concave) which avoids contact with the edge portion 12 is provided. 59) is formed. The groove part 59 is formed along the edge part 12, and has comprised the rectangular annular shape as a whole (refer FIG. 4, FIG. 5). The groove portion 59 can accommodate a portion (the edge portion 12 shown in Figs. 4 and 6) in which the edge portion 12 is rolled up toward the mask back surface 53 side. In addition, the width of the groove portion 59 is slightly larger than the width of the edge portion 12, and is set to about 200 μm in this embodiment. In addition, the groove 59 is formed at the same time as the mask back side opening 6 by half etching the surface serving as the mask back surface 53 in the stainless plate. Therefore, the mask back side opening part 56 and the groove part 59 have the same depth mutually.

In the solder ball mounting mask 51 of the present embodiment, the mask back side opening portion 56 and the groove portion 59 are formed at the same time, and then the laser punching is applied to the inner bottom surface 57 of the mask back side opening portion 56. And a plurality of mask surface side openings 55 are formed in this order. According to this manufacturing method, since punching is performed for the mask surface side opening part 55 to the location where the thickness after forming the mask back side opening part 56 is thin, there is little processing load at the time of punching, Productivity can be improved. Moreover, the mask surface side opening part 55 of a good shape can be formed with high precision compared with the case where the mask back side opening part 56 is formed after punching is performed first. In addition, by selecting optical processing rather than mechanical processing, a large number of fine holes can be efficiently formed.

In the ball mounting step, the solder back surface mounting portion 56 faces the flux supply region R2 and the groove portion 59 faces the edge portion 12 of the substrate 11 for solder ball mounting. The mask back surface 53 of the mask 51 is placed in close contact with the surface of the solder resist 33 on the first substrate main surface 13 side (see FIG. 4). At this time, a gap is formed between the inner bottom surface 57 of the mask back side opening 56 and the surface of the solder resist 33, so that the flux F1 comes into contact with and adheres to the mask back surface 53. Is avoided. In addition, since the curled portion generated in the edge portion 12 is accommodated in the groove portion 59, a situation in which the solder ball mounting mask 51 is pushed and lifted by the edge portion 12 is avoided. Subsequently, a large number of solder balls 61 having a diameter of about 100 μm is supplied to the mask surface 52 side of the solder ball mounting mask 51. As a result, the solder balls 61 fall into the mask surface side openings 55 and are placed on the pads 21 directly under the mask surface side openings 55, and the pads 21 are formed by the adhesive force of the flux F1. Is temporarily fixed at (see FIG. 6). That is, by performing a ball mounting process, the some solder ball 61 is supplied and mounted on the some pad 21 through the through-hole part 54. FIG.

Subsequently, in a reflow process, the board | substrate 11 is set in a conventionally well-known reflow furnace, and each solder ball 61 mounted on each pad 21 is heated and melt | dissolved to predetermined temperature. As a result, the solder bumps 62 of the shape shown in FIG. 7 are formed. In addition, although detailed description was abbreviate | omitted, formation of the solder bump 63 with respect to the 2nd board | substrate main surface 14 side is also performed based on this. Through the above process, the wiring board 10 having the solder bumps 62 and 63 is manufactured.

Therefore, according to this embodiment, the following effects can be acquired.

(1) Since the manufacturing method of this embodiment uses the solder ball mounting mask 51 in which the groove part 59 which avoids contact with the edge part 12 of the board | substrate 11 is used, the edge part 12 is Even if curled up toward the mask back surface 53, the edge portion 12 is accommodated in the groove portion 59 without contacting the mask back surface 53. As a result, the lifting of the solder ball mounting mask 51 due to being pushed by the edge portion 12 is prevented, so that a gap is hardly formed between the solder ball mounting mask 51 and the substrate 11. do. Therefore, the position shift of the solder ball 61 resulting from the generation | occurrence | production of a double ball (refer FIG. 10) becomes difficult, and solder bumps 62 and 63 can be formed correctly in a desired position. Therefore, the yield rate of defective products is suppressed low and the production yield of the wiring board 10 produced is high.

(2) In this embodiment, the through-hole part 54 is comprised by the mask surface side opening part 55 and the mask back side opening part 56, and the occupation area | region R4 of the mask back side opening part 56 supplies flux supply. It is formed larger than the area | region R2. Therefore, even if the flux F1 is supplied to the flux supply region R2 and the solder ball mounting mask 51 is disposed in the ball mounting step, the flux F1 does not come into contact with or adhere to the mask back surface 53. do. Therefore, sticking and position shift of the solder ball 61 by the solder ball mounting mask 51 hardly occur, and the solder bump 62 can be formed correctly in a desired position.

In addition, you may change this embodiment as shown below.

In the solder ball mounting mask 51 of the above embodiment, the through hole portion 54 is constituted by the plurality of mask surface side openings 55 and one mask back side opening 56. However, a plurality of openings constituted by one mask surface side opening portion 55 and one mask back side opening portion 56 are formed, and the occupied area of each mask back side opening portion 56 is each mask surface side opening portion. It may be larger than the occupied area of (55). In addition, the mask back side opening part 56 may be abbreviate | omitted, and each mask surface side opening part 55 may be made to open in both the mask surface 52 and the mask back surface 53. As shown in FIG.

In the above embodiment, the mask back side opening portion 56 and the groove portion 59 of the solder ball mounting mask 51 are formed by half etching, but this may be formed by cutting or the like. Moreover, in the said embodiment, although the some mask surface side opening part 55 in the solder ball mounting mask 51 was formed by laser punching, you may form these by drill processing etc. As shown in FIG.

In the above embodiment, the solder ball mounting mask 51 is formed of a metal material, but may be formed of, for example, a resin material. In this case, the mask surface side opening part 55, the mask back side opening part 56, and the groove part 59 may be formed simultaneously.

In the above embodiment, a microball having a diameter of about 100 µm was used as the solder ball 61 to be mounted. For example, a relatively large solder ball having a diameter of about 300 µm to 500 µm may also be used.

In the above embodiment, the plurality of pads 21 included in the wiring board 10 serve as pads for flip chip connecting the IC chip 71, but other electronic components or other wiring boards other than the IC chip 71 are used. It may be a pad for flip chip connection.

In the solder ball mounting mask 51 of the above embodiment, the groove portion 59 was formed at a position corresponding to the edge portion 12 on the mask back surface 53. However, like the mask 81 for solder ball mounting shown in FIG. 8, the part which rolled up to the mask back surface 83 formed in the edge part 12 in the position corresponding to the edge part 12 in the mask back surface 83 is shown. The holding part 89 to hold | maintain may be formed with a soft material. In this case, since the holding portion 89 is pushed by the edge portion 12 and deformed, a concave portion is formed, so that the lifting of the solder ball mounting mask 81 caused by the edge portion 12 caused by the edge portion 12 is raised. Is prevented.

In the manufacturing method of the said embodiment, the solder ball mounting mask 51 which provided the groove part 59 in the position corresponding to the edge part 12 in the mask back surface 53 was used. However, as shown in FIG. 9, the solder ball mounting mask 91 in which the recessed part 99 which avoids contact with the edge part 12 by bending the position corresponding to the edge part 12 is used is used. You may also do it. In this case, since the protrusion 93 protrudes toward the mask surface 92 side with the formation of the recess 99, dropping out of the solder ball mounting mask 91 of the solder ball 61 causes the protrusion 93. ) Is prevented.

Next, the technical idea grasped | ascertained by embodiment mentioned above is enumerated below.

(1) The said first means WHEREIN: After the said board | substrate preparation process and after the said ball mounting process, the flux supply process which supplies a flux to the whole said bump formation area is implemented, and the said recessed part is the said mask back surface which arose in the said edge part. A method for manufacturing a wiring board having solder bumps, characterized by avoiding contact with the edge portion by accommodating a portion curled to the side.

(2) The method for manufacturing a wiring board having solder bumps, characterized in that the concave portion is made of a soft material, and is a holding portion for holding a portion curled up toward the back side of the mask formed on the edge portion. .

10-Wiring Board 11-Board
12-edge of substrate 13-first substrate main surface as substrate main surface
21-Pad 51,81,91-Mask for Solder Ball Mount
52,92-Mask Surface 53,83-Mask Back
54-through hole 55-mask surface side opening
56-Mask back opening 57-Mask inner bottom
58-pressing part 59-groove part as recessed part
61-Solder Balls 62-Solder Bumps
99-recess R1-bump forming area
R3-occupied area of the mask surface side opening
R4-occupied area of the mask backside opening

Claims (8)

A substrate preparation step of preparing a substrate on which a plurality of pads are disposed in a bump forming region on a substrate main surface;
A through hole portion having a mask surface and a mask back surface and penetrating the mask surface and the mask back surface is formed at a position corresponding to the plurality of pads, and is an outer region of the through hole portion and the bump formation on the mask back surface side. A pressing portion for pressing the substrate in contact with the main surface of the substrate is formed at a position corresponding to the outer region of the region, and is an outer region of the pressing portion, and the edge portion at a position corresponding to an edge portion of the substrate on the mask back surface side. Using a solder ball mounting mask having a recessed portion to avoid contact with the solder ball, and supplying solder balls onto the plurality of pads through the through-holes with the solder ball mounting mask disposed on the main surface side of the substrate; A ball mounting step for mounting;
And a reflow step of heating and melting the mounted solder balls to form solder bumps.
The method according to claim 1,
And the through hole portion is formed by a mask surface side opening opened from the mask surface and a mask back side opening opened from the mask back surface.
The method according to claim 2,
The area occupied by the mask back side opening is larger than the area occupied by the mask surface side opening.
The method according to claim 2,
And the plurality of through hole portions have a plurality of mask surface side openings, and the plurality of mask surface side openings are opened at an inner bottom surface of the mask back side opening.
The method according to any one of claims 2 to 4,
And the concave portion is formed at the same time by half etching and has the same depth as each other.

The method according to any one of claims 1 to 5,
The recess is a manufacturing method of a wiring board having a solder bump, characterized in that the groove formed along the edge portion.
The method according to any one of claims 1 to 6,
And the solder ball mounting mask is a plate material having a mask plate thickness larger by 5 µm or more and 20 µm or less than the diameter of the solder ball to be mounted.
A through-hole portion having a mask surface and a mask back surface and penetrating the mask surface and the mask back surface is formed, and solder balls are supplied onto the substrate main surface through the plurality of through-hole portions in a state of being disposed on the substrate main surface side of the substrate. As a mask for solder ball mounting to be mounted,
A pressing part for contacting the substrate main surface and pressing the substrate is formed on the mask back surface side in the outer region of the through hole portion,
A mask for mounting a solder ball, wherein a recess is provided on the mask back side in the outer region of the pressing part to avoid contact with an edge of the substrate.

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