JP2006287056A - Wiring board and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wiring board which is hardly to generate a mounting defect of an integrated circuit chip and is hardly to generate the mounting defect to another board such as a mother board or the like, neither. <P>SOLUTION: The wiring board 200 using a resin as an insulating material is provided with a board central-portion 21 having a solder bump 11 (terminal) for mounting the integrated circuit chip 25 at a first main face 100p side, a board periphery 23 to be a part of the periphery of the board central-portion 21, and a plate-shaped reinforcing material 61 connected to the first main face 100p of the board periphery 23 as surrounding the solder bump 11 which is arranged in a lattice shape at the board central-portion 21. The board periphery 23 takes a shape inclining toward the first main face 100p together with the reinforcing material 61. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a wiring board and a manufacturing method of the wiring board. In particular, it is deeply related to organic wiring boards using resin as an insulating material.

In recent years, so-called multi-core processors in which a plurality of processor functions are built in one chip have been rapidly developed. The trend toward single-core processors to multi-core processors is deeply related to the fact that processor development is approaching the limits of making single-core processors more complex and sophisticated.
Japanese Patent Laid-Open No. 2004-80027

  One of the problems that emerges as the number of processors becomes multi-core is that the chip size increases. The increase in chip size also affects the wiring board on which the integrated circuit chip is mounted. A wiring board having a large size is required in proportion to the increase in chip size, but the wiring board having a large size has a weak point that warpage is likely to occur. This problem is particularly serious in an organic wiring board using a resin as an insulating material.

  When the wiring board is warped, the mounting failure of the integrated circuit chip is likely to occur, or the mounting failure of the wiring board itself to the mother board is likely to occur. Although it is conceivable to increase the thickness of the wiring board in order to reduce the amount of warpage, it goes against the trend of lowering the height of the wiring board, so that proposal cannot be easily adopted.

  In view of the above problems, an object of the present invention is to provide a wiring board in which mounting failure of an integrated circuit chip hardly occurs and mounting failure on another substrate such as a mother board hardly occurs. A method for manufacturing the wiring board is also provided.

Means for Solving the Problems and Effects of the Invention

  In order to solve the above-described problems, a wiring board according to the present invention is a wiring board using a resin as an insulating material, and has a substrate central portion having terminals connected to an integrated circuit chip on the first main surface side, and a substrate central portion. A main feature is that it includes an outer peripheral portion that is an outer portion and is inclined toward the first main surface side from the central portion of the substrate. In this specification, the “main surface” refers to a surface having the largest area.

  While the thermal expansion coefficient of the integrated circuit chip is about 4 ppm / ° C., the thermal expansion coefficient of the organic wiring substrate using a resin as an insulating material varies depending on the type of resin used and the wiring density, but is 30 ppm to 80 ppm / ° C. And high. Therefore, when the reflow process for mounting the integrated circuit chip and the curing process of the underfill material are performed, the integrated circuit chip expands and contracts slightly, but the wiring board expands and contracts greatly. As a result, as shown in FIG. 16, a convex warp occurs on the side on which the integrated circuit chip 25 is mounted. When mounting the wiring board 90 on the motherboard MB by placing the solder ball 92 on the terminal pad 91 on the back surface side in such a warp state, as shown in FIG. A large gap SH is generated. This gap SH becomes a cause of increasing the occurrence probability of mounting failure.

  The above-mentioned present invention is intended to cancel the warpage occurring when the integrated circuit chip is mounted by giving a warp in the reverse direction in advance, but the central portion of the substrate on which the terminals connected to the integrated circuit chip are formed. Is characterized in that the outer periphery of the substrate is warped while being flat. Simply introducing the idea of offsetting warpage with warpage only makes it difficult to mount integrated circuit chips. However, according to the wiring board of the present invention, since only the outer peripheral part of the board is actively warped, the flatness of the central part of the board is not lost and there is no problem in mounting the integrated circuit chip. Then, the amount of warpage after mounting the integrated circuit chip can be reduced by offsetting the warpage occurring when the integrated circuit chip is mounted by the inclination (bounce) of the outer peripheral portion of the substrate. Therefore, the wiring board according to the present invention is less likely to cause mounting failure of the integrated circuit chip and is less likely to cause mounting failure to another substrate such as a mother board.

  In one preferred embodiment, the wiring board of the present invention described above is provided with a separate component (another component such as a mother board) on the second main surface side opposite to the first main surface side on which the terminals connected to the integrated circuit chip are provided. In order to make a solder connection with the substrate), a plurality of back terminals arranged in a grid pattern may be provided over both the central portion of the substrate and the outer peripheral portion of the substrate. For example, two types of BGA (Ball Grid Array) and PGA (Pin Grid Array) are conceivable as wiring boards targeted by the present invention. The BGA wiring board is mounted on the motherboard with solder balls arranged on the back terminal (referred to as the back terminal pad in the embodiment), and the PGA wiring board is mounted on the motherboard with pins attached to the back terminal. In the case of the PGA wiring board, even if some warping occurs, it can be forcibly mounted on the motherboard by pushing the pins into the pin holes provided on the motherboard. However, if the BGA wiring board is greatly warped, the probability of mounting failure increases due to the gap SH between the solder ball 92 and the motherboard MB, as described above with reference to FIG. . That is, the present invention is particularly effective when applied to a BGA wiring board. Of course, there is no doubt that it is also effective for PGA wiring boards.

  Moreover, the wiring board of the present invention can be manufactured by the following method. That is, the method for manufacturing a wiring board according to the present invention uses a resin as an insulating material and has a substrate central portion having terminals connected to the integrated circuit chip on the first main surface side, and a substrate around the substrate central portion. A wiring board workpiece having an outer peripheral portion, and an opening for forming a space on the first main surface where the entire central portion of the board faces when contacting the wiring board workpiece from the first main surface side. Forming a space on the second main surface with a width that includes the entire opening of the first support in the in-plane direction when contacting the first support and the wiring board workpiece from the second main surface side. After preparing the support, the first support comes into contact with the outer peripheral portion of the substrate from the first main surface side, and the substrate outer peripheral portion is supported by the second support from the second main surface side. The body, the wiring board work, and the second support are arranged in this order in the board thickness direction. The first support body is pressed from the side opposite to the side that contacts the wiring board workpiece while the outer peripheral portion of the board is supported by the second support body, and the wiring board workpiece is biased to the second main surface side. Thus, a main feature is that a circuit board work is formed so that the outer peripheral portion of the substrate is inclined toward the first main surface while maintaining the flatness of the central portion of the substrate.

  According to the above manufacturing method, the upper and lower sides (the first main surface side and the second main surface side) of the substrate central portion of the wiring board work are spaces, and the first support and the second support are respectively provided above and below the outer peripheral portion of the substrate. Place the body. The space formed by the second support in the in-plane direction has a size including the inner peripheral edge of the opening of the first support on the first main surface side (see FIG. 6). And a 1st support body, a wiring board workpiece | work, and a 2nd support body are piled up, and a 1st support body is pressed. At this time, since the entire substrate central portion faces the space formed by the second support, the load from the first support does not hang directly on the substrate central portion. As a result, it is possible to form the wiring board workpiece so that the outer peripheral part of the board is inclined (splashed up) obliquely while maintaining the flatness of the central part of the board. In addition, since the load transmitted by the first support to the wiring board workpiece has an in-plane distribution, there is no extreme step between the central part of the board and the outer peripheral part of the board, and the inner layer wiring is not damaged. .

  In one preferred embodiment, the first support described above is a frame-shaped plate-like body having through holes in the thickness direction for exposing a plurality of terminals arranged in a lattice at the center of the substrate. Can do. Further, the above-mentioned second support has a wide-opening that includes the entire inner peripheral edge forming the through hole of the first support in the in-plane direction, and a space where the entire central portion of the substrate faces is the second main. It can be set as the frame-shaped plate-shaped body formed on a surface. In the process of forming the wiring board workpiece, the wiring board workpiece can be biased toward the second main surface side by sinking the central portion of the board into the opening of the second support. By making both the first support body and the second support body into a frame form, it is possible to easily adjust the width of the space formed above and below the center part of the board, and based on supporting the surface of the wiring board work, Local deformation of the wiring board workpiece can be prevented.

  In addition, the step of forming the wiring board work includes a solder in which a laminate of the first support, the wiring board work, and the second support is arranged on the surface of the terminal of the wiring board work, or a solder constituting the terminal. It is preferable to carry out heating at a temperature lower than the melting point. This makes it difficult to cause damage such as cracks in the wiring formed inside the wiring board workpiece, and reduces the residual stress of the wiring board to be obtained.

  By the way, as one technique for solving the problem of warping of the wiring board, there is a technique of attaching a reinforcing material to the surface on which the integrated circuit chip is mounted. Since the reinforcing material improves the stiffness of the wiring board, it has an effect of suppressing warpage. However, when the wiring board for an integrated circuit chip having a large size such as a multi-core processor is used, the board size is considerably large. Therefore, the effect of suppressing warping is small by simply attaching a reinforcing material. Increasing the thickness of the reinforcing material is not unthinkable, but it goes against the trend of low-profile wiring boards. Also, if the material of the reinforcing material is improved, the development cost is high. In response to these problems, the present inventors propose the following wiring board.

  That is, in order to solve the problem, the second of the wiring boards of the present invention is a wiring board using a resin as an insulating material, and has a central portion of the board having terminals connected to the integrated circuit chip on the first main surface side. A peripheral portion of the substrate that is a portion around the central portion of the substrate, and a plate-shaped reinforcing member that is joined to the first main surface of the peripheral portion of the substrate so as to surround a plurality of terminals arranged in a lattice pattern in the central portion of the substrate. The main feature is that the outer peripheral portion of the substrate is inclined with the reinforcing material toward the first main surface.

  The above-mentioned present invention is intended to cancel the warpage occurring when the integrated circuit chip is mounted by giving a warp in the reverse direction in advance, but the substrate on which the terminals for mounting the integrated circuit chip are formed. The center portion is flat and the substrate outer peripheral portion is warped together with the reinforcing material. Simply introducing the idea of offsetting warpage with warpage only makes it difficult to mount integrated circuit chips. However, according to the wiring board of the present invention, since only the outer peripheral part of the board is actively warped, the flatness of the central part of the board is not lost and there is no problem in mounting the integrated circuit chip. Then, the amount of warpage after mounting the integrated circuit chip can be reduced by offsetting the warpage occurring when the integrated circuit chip is mounted by the inclination (bounce) of the outer peripheral portion of the substrate. Therefore, the wiring board according to the present invention is less likely to cause mounting failure of the integrated circuit chip and is less likely to cause mounting failure to another substrate such as a mother board.

  Moreover, the wiring board of the present invention provided with a reinforcing material can be manufactured by the following method. That is, the second method of manufacturing a wiring board according to the present invention uses a resin as an insulating material and has a central portion of the substrate having terminals connected to the integrated circuit chip on the first main surface side, and a portion around the central portion of the substrate. A step of producing a wiring board work provided with a certain board outer peripheral part, and a through-hole for exposing a plurality of terminals arranged in a lattice form in the central part of the board when contacting the wiring board work from the first main surface side In the in-plane direction, the whole of the inner peripheral edge forming the through-hole of the reinforcing material when the plate-shaped reinforcing material joined to the outer peripheral portion of the board is brought into contact with the wiring board workpiece from the second main surface side is formed. After preparing a support body that forms a space of the included area on the second main surface side of the central part of the board, a state in which an adhesive containing a thermosetting resin is interposed between the reinforcing material and the wiring board workpiece Thus, the reinforcing material comes into surface contact with the outer periphery of the substrate from the first main surface side. The step of arranging the reinforcing material, the wiring board work, and the support in this order in the thickness direction so that the substrate outer periphery is supported by the second support from the second main surface side, and the substrate outer periphery by the support. In a state where the wiring board work is supported, the reinforcing material is pressed from the side opposite to the side in contact with the wiring board work so that the load is concentrated on the inner peripheral edge forming the through-hole. And a step of bonding the wiring board workpiece and the reinforcing material by curing the adhesive while maintaining the biased state.

  According to the above manufacturing method, the upper and lower sides (the first main surface side and the second main surface side) of the substrate center portion of the wiring board work are spaces, and the reinforcing material and the support are disposed on the upper and lower portions of the outer peripheral portion of the substrate, respectively. . The space formed by the support on the second main surface side in the in-plane direction has a size that includes the inner peripheral edge of the reinforcing material (refer to the description of FIG. 6 for details). Then, the reinforcing material, the wiring board workpiece, and the support are overlapped, and the reinforcing material is pressed so that the load is concentrated on the inner peripheral edge. The load from the reinforcing material is concentrated near the boundary between the center of the substrate and the outer periphery of the substrate, but the entire center of the substrate faces the space formed by the support, so the load is directly suspended from the center of the substrate. Absent. As a result, it is possible to form the wiring board workpiece so that the outer peripheral portion of the substrate is inclined (splashed up) while maintaining the flatness of the central portion of the substrate. Further, since the load transmitted to the wiring board workpiece by the reinforcing material has an in-plane distribution, an extreme step does not occur between the central part of the board and the outer peripheral part of the board, and the inner layer wiring is not damaged. Furthermore, since the reinforcing material and the wiring board work are joined while pressing the reinforcing material, the wiring board obtained even when the load of the reinforcing material is removed is difficult to return to the original shape.

  In one preferred embodiment, the support described above has a wide-mouthed through hole including the entire inner peripheral edge forming the through hole of the reinforcing material in the in-plane direction, and a space that the entire central portion of the substrate faces is provided. It can be set as the plate-shaped body of the frame form formed on two main surfaces. And, in the step of joining the wiring board workpiece and the reinforcing material, the reinforcing material is pressed while supporting the outer peripheral portion of the substrate with the support, and the central portion of the substrate is submerged in the through hole of the supporting body. The wiring board workpiece can be biased in the direction of the support. By making the support body a frame-shaped plate-like body, the size of the space formed on the second main surface side of the central portion of the substrate can be easily adjusted, and local deformation of the wiring board workpiece can be prevented. .

  More specifically, the reinforcing material may be in the form of a frame having a rectangular through hole, while the support may be in the form of a frame having a circular through hole having a diameter larger than the diagonal of the through hole of the reinforcing material. . Then, in the in-plane direction, the reinforcing material, the wiring board work, and the support are arranged so that the entire inner peripheral edge forming the through hole of the reinforcing material is in a relative positional relationship within the inner peripheral edge forming the through hole of the support. The process of arranging the body in the thickness direction in this order is performed. In this way, when the reinforcing material is pressed, the load tends to concentrate on the inner peripheral edge of the reinforcing material, so that the central portion of the substrate can be submerged in the opening of the support. In addition, in the in-plane direction, the through hole of the support body is sized to encompass the entire through hole of the reinforcing material, so that a load is uniformly applied to the entire inner peripheral edge of the reinforcing material. Local deformation can be prevented.

  In addition, the step of joining the wiring board workpiece and the reinforcing material is performed by soldering a laminated body of the reinforcing material, the wiring board workpiece, and the support on the surface of the terminal of the wiring board workpiece, or solder constituting the terminal. It can be carried out while heating at a temperature lower than the melting point of the adhesive and the adhesive is cured. If it does in this way, this reinforcing material and a wiring board work can be joined easily, pressing a reinforcing material.

  In addition, in a vacuum chamber in which at least a part of the wall is formed of a flexible film, a plate-like laminate in which a reinforcing material, a wiring board workpiece, and a support are arranged in this order in the thickness direction is reinforced. The material can be formed so as to face the flexible film. Then, the inside of the vacuum chamber is evacuated in a state where the wiring board work is supported by the support body, and the surface contact state between the reinforcing material and the substrate outer peripheral portion is obtained by bending the flexible film and pressing the reinforcing material at atmospheric pressure. While maintaining, the circuit board work is urged toward the second main surface so as to sink the central portion of the substrate into the through hole of the support. If it does in this way, when the inside of a vacuum chamber is exhausted, a reinforcing material can be pressed on a surface by a flexible membrane. At this time, since the reinforcing material has a frame shape, the flexible film hangs in the through hole. Then, since the load concentrates on the inner peripheral edge of the reinforcing material, it is possible to cause an inward tilt on the outer peripheral portion of the substrate together with the reinforcing material.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a schematic sectional view of a wiring board according to the present invention. The wiring substrate 100 includes a substrate central portion 21 that is a portion on which an integrated circuit chip is mounted, and a substrate outer peripheral portion 23 that is an outer portion surrounding the substrate central portion 21. On the first main surface 100p side of the wiring substrate 100, solder bumps 11 for mounting the integrated circuit chip are provided only on the substrate central portion 21 so as to correspond to the metal terminal pads 10 (FIG. 2). The solder bump 11 and the metal terminal pad 10 constitute a terminal connected to the integrated circuit chip. In addition, on the second main surface 100q side, a plurality of back surface terminal pads 17 are provided in a matrix form over both the substrate center portion 21 and the substrate outer peripheral portion 23 for solder connection to another substrate such as a mother board.

  As shown in FIG. 1, the substrate central portion 21 and the substrate outer peripheral portion 23 are configured as a single unit that is smoothly connected, but the substrate outer peripheral portion 23 is inclined from the substrate central portion 21 toward the first main surface 100 p side. The shape is inclined to When the wiring board 100 having such a shape is used, the following significant effects can be obtained when the semiconductor device 300 is assembled. FIG. 4 shows a procedure for assembling the semiconductor device.

  As shown in FIG. 4, the integrated circuit chip 25 is mounted on the central portion 21 of the wiring substrate 100. The integrated circuit chip 25 is in contact with the solder bump 11 in the central portion 21 of the substrate. The reflow process is performed while maintaining this state. In the reflow process, the wiring board 100 is heated to a temperature higher than the melting point of the solder constituting the solder bump 11. Thereafter, a curing process is performed in which the gap between the integrated circuit chip 25 and the wiring substrate 100 is filled with the underfill material UF and cured. Since the underfill material UF is generally made of a thermosetting resin, for example, an epoxy resin, the curing process is a heat treatment process for curing the underfill material UF. The curing process is performed in a temperature range lower than the temperature of the reflow process.

  By performing the reflow process and the curing process as described above, the semiconductor device 300 in which the integrated circuit chip 25 is mounted on the wiring substrate 100 is obtained. For example, even if the integrated circuit chip 25 is a large chip such as a multi-core processor and the size of the wiring board 100 is large (for example, □ 35 mm or more), the semiconductor device 300 using the wiring board 100 is flat. Is good. This is because, before the integrated circuit chip 25 is mounted, the wiring substrate 100 has a warp in which the first main surface 100p side is concave as shown in FIG. 1, and this warp causes the reflow process and the cure process in FIG. This is because the warping that occurs is offset. In addition, even if there is a warp in advance, the flatness of the central portion 21 of the substrate is not lost, so the probability that a mounting failure of the integrated circuit chip 25 will occur is small.

  On the other hand, the conventional wiring board is certainly excellent in flatness before the integrated circuit chip 25 is mounted, as shown in FIG. However, in the state of the semiconductor device 500 obtained by performing the reflow process and the curing process, the flatness of the wiring board 90 is greatly lost. As shown in FIG. 16, when the semiconductor device 500 having such a warp is mounted on the motherboard MB by placing the solder balls 92 on the back surface terminal pads 17 of the wiring board 90 portion, A large gap SH is generated between the motherboard MB. When the reflow process is performed in a state where there is such a large gap SH, the probability of occurrence of mounting defects such as insufficient strength and poor conduction increases. Conventionally, since the substrate size was small (for example, less than □ 35 mm), such a gap SH was also relatively small and was not directly connected to the problem of poor mounting, but warpage when the semiconductor device 500 was formed as the substrate size increased. The problem comes to the surface. The wiring board 100 of the present invention can be said to be extremely effective for such an increase in board size. Of course, it is effective even when the substrate size is small. Note that the wiring boards 100 and 200 described in this specification have a size of □ 50 mm.

  In addition, when the warpage generated in the reflow process and the curing process is large, the warpage does not completely cancel out, and as a result, the first main surface 100p is convex, but this has the maximum effect of reducing warpage. It means that it was demonstrated. If the warpage can be reduced to a level at which mounting failure to the motherboard MB does not occur, it can be said that there is no need to completely cancel the warpage generated in the reflow process and the curing process.

  In FIG. 4, the integrated circuit chip 25 is directly mounted on the wiring substrate 100. However, an intermediate substrate is disposed between the wiring substrate 100 and the integrated circuit chip 25, and wiring is performed via the intermediate substrate. The integrated circuit chip 25 may be mounted on the substrate 1. Such an intermediate substrate uses ceramic as an insulating material, has a thermal expansion coefficient between the wiring substrate 100 and the integrated circuit chip 25, and plays a role of absorbing the difference between the two.

Next, the internal structure of the wiring board 100 will be described.
FIG. 2 shows a detailed cross-sectional structure of the wiring board 100 of FIG. The wiring substrate 100 has a predetermined pattern on both surfaces of the plate-like core 2 made of a heat-resistant resin plate (for example, bismaleimide-triazine resin plate), a fiber reinforced resin plate (for example, glass fiber reinforced epoxy resin), or the like. Core conductor layers M1 and M11 are formed, respectively. These core conductor layers M1 and M11 are formed as a plane conductor pattern that covers most of the surface of the plate-like core 2, and are used as a power supply layer or a ground layer. On the other hand, a through-hole 12 drilled by a drill or the like is formed in the plate-like core 2, and a through-hole conductor 30 that connects the core conductor layers M 1 and M 11 to each other is formed on the inner wall surface thereof. The through hole 12 is filled with a resin filling material 31 such as an epoxy resin.

  Moreover, dielectric layers V1 and V11 made of the thermosetting resin composition 6 are formed on the core conductor layers M1 and M11, respectively. Further, conductor layers M2 and M12 having metal terminal pads 10 and 17 are formed on the surface by Cu plating. The core conductor layers M1, M11 and the conductor layers M2, M12 are interconnected by vias 34, respectively. The via 34 has a via hole 34h and a via conductor 34s filled in the via hole 34h.

  On the first main surface MP1 of the plate-like core 2, the core conductor layer M1, the dielectric layer V1, and the conductor layer M2 form the first wiring laminated portion L1. On the second main surface MP2 of the plate-like core 2, the core conductor layer M11, the dielectric layer V11, and the conductor layer M12 form the second wiring laminated portion L2. In either case, dielectric layers and conductor layers are alternately laminated, and a plurality of metal terminal pads 10 and 17 are formed on the dielectric layers V1 and V11, respectively. The metal terminal pad 10 on the first wiring laminated portion L1 side is a terminal pad for flip chip connection of the integrated circuit chip directly or via an intermediate substrate, and constitutes a solder land on which the solder bump 11 is placed. . The metal terminal pad 17 on the second wiring laminated portion L2 side is a back surface terminal pad for connecting the wiring board 100 itself to another board such as a mother board by a pin grid array (PGA) or a ball grid array (BGA). is there.

  As shown in FIG. 3A, the terminal pads 10 on the first main surface 100p side are arranged in a grid pattern in the substrate central portion 21 which is the central portion of the wiring substrate 100, and solder bumps formed thereon, respectively. 11 and the chip mounting portion 4 are formed. Further, as shown in FIG. 3B, the back surface terminal pads 17 on the second main surface 100q side are also arranged in a grid pattern. Solder resists 8 and 18 made of a thermosetting resin composition or a photosensitive resin composition are disposed on the conductor layers M2 and M12, respectively. In the solder resists 8 and 18, openings 8 a and 18 a are formed so as to correspond to the metal terminal pads 10 and 17 on a one-to-one basis in order to expose the metal terminal pads 10 and 17. The solder bump 11 provided on the first wiring laminated portion L1 side is composed of Sn—Pb solder or solder that does not substantially contain Pb, such as Sn—Ag, Sn—Cu, Sn—Ag—Cu, or Sn—Sb. can do.

Next, a method for manufacturing the wiring board 100 will be described.
The wiring board 100 can be manufactured by forming the wiring laminated portions L1 and L2 on the main surfaces MP1 and MP2 of the plate-like core 2 by a known buildup method or the like. Dielectric layers V1 and V11 are formed as follows, for example. That is, a thermosetting adhesive film obtained by forming a thermosetting resin composition varnish into a film is laminated, and a transparent mask (for example, a glass mask) having a pattern corresponding to the via hole 34h is overlaid and exposed. The film portions other than the via hole 34h are cured by this exposure, while the via hole 34h portion remains uncured, so that the via hole 34h can be easily formed in an intended pattern by removing it by dissolving it in a solvent. (So-called photovia process). Note that a laser via process in which the via hole 34h is formed by a laser may be employed instead of the photo via process.

  Each of the conductor layers M1, M2, M11, and M12 can be formed by pattern Cu plating using a photolithography technique. Then, after forming the conductor layer M2 on one main surface side and the conductor layer M12 on the other main surface side, the conductor layers M2 and M12 are covered with the solder resists 8 and 18, and the metal terminal pads 10 and 17 are covered. Openings 8a and 18a are formed at the formation positions. Then, Ni / Au plating is performed on the surfaces of the metal terminal pads 10 and 17, and the solder paste is filled in the openings 8 a of the solder resist 8. Thus, the solder bumps 11 are formed on the metal terminal pads 10 on the side where the integrated circuit chip is mounted.

  The wiring board 100 shown in FIG. 1 can be obtained by performing the following forming process on the wiring board workpiece formed up to the solder bumps 11 as described above. 5 to 8 specifically illustrate the molding process. First, as shown in FIG. 5, the first support 27, the wiring board workpiece 100w, and the second support 29 are overlapped in this order to form a laminated body 40A. The first support 27 is a plate-like body having an outer shape substantially the same size as the wiring board workpiece 100w. When the first supporting body 27 is superimposed on the board outer peripheral portion 23 of the wiring board workpiece 100w from the first main surface 100p side, The solder bumps 11 (including the terminal pads 10) arranged in the central portion 21 are in the form of a frame having through holes 27h in the thickness direction for exposure without contact. The through hole 27h has a square shape according to the shape of the integrated circuit chip. The material used for the first support 27 is not particularly limited, such as resin, metal, ceramic, or a composite material thereof. However, since it is desirable that the wiring board workpiece 100w is formed with an appropriate rigidity, a metal plate (Cu plate or SUS board) having a thickness similar to that of the wiring board workpiece 100w is used as the wiring board workpiece 100w. What is cut in the same shape as that and provided with a through hole 27t may be used as the first support 27.

  On the other hand, the second support body 29 is a plate-like body having an outer shape substantially the same size as the wiring board workpiece 100w, similar to the first support body 27, and the substrate of the wiring board workpiece 100w from the second main surface 100q side. When superposed on the outer peripheral portion 23, a frame shape having a circular through hole 29h is formed so that a space is directly below the central portion 21 of the substrate. The material used for the second support 29 is not particularly limited, such as resin, metal, ceramic, or a composite material thereof. However, it is desirable to use a resin sheet such as polyethylene terephthalate, polypropylene, or polyethylene from the viewpoint of preventing contamination from adhering to the back surface terminal pad 17 of the wiring board workpiece 100q. Since such a resin sheet is usually thin (several tens of μm), it is preferable to use a laminate of a plurality of sheets as the second support 29. Further, the thickness of the second support 29 can be made smaller than that of the wiring board workpiece 100w, and may be adjusted according to the warp desired to be imparted by molding. Further, the through hole 29t of the second support 29 is not limited to a circle, and may be, for example, a square (square) or an ellipse.

  As can be seen from the perspective view of FIG. 5, the diameter of the through hole 29 h of the second support 29 is larger than the length of the diagonal line of the through hole 27 h of the first support 27. Therefore, as shown in the projection view of FIG. 6, in the in-plane direction of the stacked body 40A, the inner peripheral edge 27t that forms the through hole 27h of the first support 27 is the inner peripheral edge that forms the through hole 29h of the second support 29. The whole fits inside 29t. Further, the space that the wiring board workpiece 100w faces on the second main surface 100q side is wider in the in-plane direction than the space that faces the first main surface 100p side. By using the first support body 27 and the second support body 29 that have such a relationship, the wiring board workpiece 100w can be formed as shown in FIG.

  FIG. 7 is an explanatory view showing a state in which the wiring board workpiece 100w is formed by applying a load to the laminate 40A. Specifically, while the substrate outer peripheral portion 23 of the wiring board workpiece 100w is supported by the second support 29, a load is applied to the first supporting body 27 from the side opposite to the side in contact with the wiring board workpiece 100w. 100 w is urged toward the second support 29. It is desirable to apply a certain load or more to the entire surface of the first support 27. Since the opposite side of the inner peripheral portion 271 across the wiring board workpiece 100w is a space, if the load is concentrated and hung on the inner peripheral portion 271 while suppressing the outer side, a broken line is shown in the figure. As shown, the substrate central portion 21 gradually sinks into the through hole 29h of the second support 29, thereby forming the wiring substrate workpiece 100w. However, since the load is not directly applied to the substrate central portion 21 where the solder bumps 11 are formed, the flatness of the substrate central portion 21 is maintained. Further, the substrate outer peripheral portion 23 also has a slightly large force applied to a portion close to the substrate central portion 21, but is also effective in suppressing a portion far from the substrate central portion 21, thereby causing a step by causing extreme deformation. There is no problem. In the method shown in the present embodiment, such points are also taken into consideration.

  FIG. 8 is a cross-sectional view showing how the wiring board workpiece 100w is molded using the board manufacturing apparatus 41 (board forming apparatus). According to this board manufacturing apparatus 41, the load distribution indicated by the arrow in FIG. 7 can be easily applied to the first support 27, so that the wiring board workpiece 100w can be formed with high efficiency and high accuracy. Is possible. Such a substrate manufacturing apparatus 41 includes a vacuum chamber 44, a fixture 47 for fixing the stacked body 40A in the vacuum chamber 44, and an aspirator or a vacuum pump (not shown).

  In the vacuum chamber 44, when the laminated body 40 </ b> A is disposed at a predetermined position of the fixture 47, the wall portion of the laminated body 40 </ b> A facing the first support 27 is constituted by the flexible film 43 and the rest is constituted by the metal wall 45. It is a thing. The flexible film 43 is made of a resin having rubber elasticity, for example, silicon rubber. The fixing tool 47 surrounds the laminated body 40A, and is a component that prevents the first support 27, the wiring board workpiece 100w, and the second support 29 from shifting in-plane during the molding process. In addition, a thin metal plate 49 is disposed between the laminate 40A and the flexible film 43.

  First, as shown in the upper diagram of FIG. 8, the stacked body 40 </ b> A is set at a predetermined position inside the fixture 47. Since the fixture 47 has a slightly lower height than the laminated body 40A, the first support 27 protrudes slightly from the fixture 47, but the height of the fixture 47 does not shift in the in-plane direction. Adjustments have been made. A thin metal plate 49 is placed on the stacked body 40A. Next, the inside of the vacuum chamber 44 is evacuated. As the inside of the vacuum chamber 44 is depressurized, the flexible film 43 is pressed by the atmospheric pressure and bent as shown in the middle diagram of FIG. The first support 27 receives a pressing force from the flexible film 43 through the thin metal plate 49 and biases the wiring board workpiece 100 w toward the second support 29. The substrate outer peripheral portion 23 of the wiring board workpiece 100 w is supported by the second support 29, but a space just below the substrate center portion 21 is a space formed by the through hole 29 h of the second support 29.

  When the vacuum chamber 44 is evacuated as described above, the metal thin plate 49 is slightly bent and enters the through hole 27h of the first support 27, but does not come into direct contact with the wiring board workpiece 100w. That is, the metal thin plate 49 prevents the flexible film 43 from directly contacting and pressing the wiring board workpiece 100w. In this way, the load from the flexible film 43 tends to concentrate on the inner peripheral portion 271 of the first support 27. As a result, inward tilts (tilts) gradually occur in the substrate outer peripheral portions 23 and 23, and the substrate central portion 21 gradually sinks into the through holes 29h of the second support 29 while maintaining flatness. The wiring board workpiece 100w is formed in a desired shape, and the wiring board 100 of FIG. 1 is obtained. Such an action is as described in FIG. Further, by adopting a configuration in which the flexible film 43 and the metal thin plate 49 are not in contact with the solder bump 11, contamination adheres to the solder bump 11 and the solder bump 11 (usually shaped so that the top surface is flattened). ) Is also a bird with two stones.

  8 can be performed while heating the stacked body 40A by the infrared heaters 51 and 51. In this way, the residual stress of the obtained wiring board 100 can be reduced. The infrared heater 51 shown in the middle diagram of FIG. 8 may be disposed in the vacuum chamber 44. The laminated body 40A is heated in a temperature range lower than the melting point of the solder constituting the solder bump 11 of the wiring board workpiece 100w.

  Next, a modified example of the laminated body in which the first support, the wiring board workpiece, and the second support are overlapped will be described. FIG. 9 illustrates another example of the laminate in a top view. As shown in FIG. 9, the laminated body 40B is configured by disposing sheet-like second supports 35 at the four corners on the second main surface 100q side of the wiring board workpiece 100w. The first support 27 and the wiring board workpiece 100w are the same as those in the previous embodiment. The second support 29 in the previous embodiment was in the form of a frame having a circular through hole 29h. However, like the second support 35 in FIG. Anything that can be supported is acceptable. From this, it can be seen that a through hole is not essential in the second support. However, in order to obtain the operation described with reference to FIG. 7, the second main surface 100q of the substrate central portion 21 (just below the substrate central portion 21) needs to be a space. Alternatively, the second supports 35 and 35 may be arranged in advance in the vacuum chamber 44 as a part of the substrate manufacturing apparatus 41, and the stacked body 40 </ b> C may be prepared in the vacuum chamber 44.

  FIG. 10 illustrates another example of the laminated body in a cross-sectional view. In the previous embodiment, it has been described that the second support 29 is a laminate of a plurality of resin sheets. However, the second support 36 of the laminate 40C shown in FIG. The sizes (diameters) of the through holes of the combined individual resin sheets are different from each other. Specifically, the second support 36 includes three resin sheets 37, 38, and 39. Between the through hole 37h formed by the first resin sheet 37 which is a resin sheet in contact with the wiring board workpiece 100w, and the through hole 39h formed by the second resin sheet 39 which is the resin sheet located farthest from the wiring board workpiece 100w. The through holes 38h formed by the third resin sheet 38 that are positioned are concentric with each other, but the diameter gradually decreases as the distance from the wiring board workpiece 100w increases in the thickness direction. As a result, the second support 36 has a stepped bowl shape as a whole. When the second support body 36 has such a bowl shape, the wiring board workpiece 100w is formed while supporting the substrate outer peripheral portion 23 for each step, so that generation of a step due to excessive forming is suppressed. The effect and the effect which prevents the damage to the wiring inside a board | substrate can be anticipated.

(Second embodiment)
FIG. 11 is a cross-sectional view of a wiring board according to the second embodiment of the present invention, and FIG. 12 is a top view of the wiring board of FIG. The wiring board 200 includes a wiring board body 100 and a reinforcing member 61 bonded to the first main surface 100p of the wiring board body 100. The wiring board main body 100 is the wiring board 100 itself described in the previous embodiment, but in the present embodiment, the wiring board main body 100 is considered to be the wiring board 200 including the reinforcing member 61, and hence is referred to as a “main body”. In addition, most of the description of the previous embodiment can be incorporated into this embodiment.

  As shown in FIG. 11, on the first main surface 100p side of the wiring board 200, solder bumps 11 for mounting an integrated circuit chip are formed on the substrate central portion 21 so as to correspond to the metal terminal pads 10 (FIG. 2). Only provided. The reinforcing member 61 is disposed so as to surround the solder bump 11, and the substrate outer peripheral portion 23 forms an inclined shape with the reinforcing member 61 from the substrate central portion 21 to the first main surface 100 p side. . The reinforcing member 61 is a plate-like body having an outer shape that matches the wiring board main body 100, and has a through hole 61h that exposes the substrate central portion 21 on which the solder bumps 11 are formed on the first main surface 100p side. It has a frame shape. A metal can be used as the material of the reinforcing member 61. For example, a kind of metal selected from the group of Cu, SUS, Kovar and 42 alloy can be used. In particular, Cu can be recommended from the viewpoints of economy and heat dissipation of the wiring board 200.

  As shown in FIG. 11, the reinforcing member 61 has a shape inclined to the first main surface 100 p side together with the substrate outer peripheral portion 23. In the case of such a shape, as shown in FIG. 13, the flatness of the semiconductor device 400 obtained by mounting the integrated circuit chip 25 on the substrate central portion 21 and performing the reflow process and the curing process is improved. Can do. The reason is that, as described above, the action of canceling the warp with the warp works during the reflow process and the cure process. Moreover, according to the wiring board 200 of this embodiment, since the reinforcing material 61 is joined to the board outer peripheral portion 23 of the wiring board body 100, the stiffness of the wiring board 200 as a whole is higher than that of the wiring board body 100 alone. From the viewpoint of improving the flatness of the semiconductor device 400, it is advantageous to provide the reinforcing member 61.

Next, a method for manufacturing the wiring board 200 of FIG. 11 will be described.
Basically, it can be considered that the first support 27 in the previous embodiment is replaced with the reinforcing member 61. First, as shown in FIG. 5, the reinforcing member 61, the wiring board workpiece 100w, and the support body 29 are arranged in this order in the thickness direction to obtain a stacked body 40D. The wiring board workpiece 100 w is a portion that should become the wiring board main body 100. The support body 29 (referred to as the second support body 29 in the previous embodiment) has a frame shape having a circular through hole 29h having a diameter larger than the diagonal line of the through hole 61h of the reinforcing member 61. Accordingly, as shown in parentheses in FIG. 6, in the in-plane direction of the laminate 40D, the entire inner peripheral edge 61t (square) forming the through hole 61h of the reinforcing member 61 forms the through hole 29h of the support body 27. The relative positional relationship is within 29t (circular). Further, as described above, the support 29 can be a part of the substrate manufacturing apparatus 41. In that case, the stacked body 40D is formed in the vacuum chamber 44 of the substrate manufacturing apparatus 41 shown in FIG.

  Further, since the reinforcing member 61 is bonded to the wiring board workpiece 100w with an adhesive, the adhesive is applied to the substrate outer peripheral portion 23 of the wiring board workpiece 100w or the back surface of the reinforcing member 61, and the reinforcing member 61 and the wiring board workpiece 100w are connected. An adhesive 62 is interposed therebetween. By using a thermosetting epoxy adhesive as the adhesive 62, the process of joining the reinforcing member 61 to the wiring board workpiece 100w and the molding process of the wiring board workpiece 100w described in the previous embodiment are simultaneously performed. Can be made. That is, as shown in FIG. 14, the laminated body 40D is disposed in the vacuum chamber 44 of the substrate manufacturing apparatus 41, and the wiring board workpiece 100w is formed while the laminated body 40D is heated by the infrared heaters 51 and 51. In this case, the adhesive 62 is naturally cured, and the reinforcing material 61 can be fixed to the wiring board workpiece 100w.

  As shown in FIG. 14, when the laminated body 40 </ b> D is disposed in the vacuum chamber 44 of the substrate manufacturing apparatus 41 and the vacuum chamber 44 is further evacuated, the flexible film 43 is bent and presses the reinforcing member 61 through the metal thin plate 49. To do. As described above, since the load from the flexible film 43 is strongly applied to the inner peripheral portion of the reinforcing member 61, the board outer peripheral portions 23 and 23 of the wiring board workpiece 100 w and the reinforcing member 61 are tilted inward (inclined). 11 is obtained in such a manner that the central portion 21 of the substrate gradually sinks into the through hole 29h of the support 29 while maintaining flatness. Further, since the adhesive 62 is cured just when sufficient molding is performed, even if the vacuum chamber 43 is purged, the elastic return amount of the substrate outer peripheral portion 23 can be small.

  In the present specification, the wiring board in which the wiring layers and the resin insulating layers are alternately formed on the plate core 2 has been described as an example. However, the present invention is applied to a wiring board having no plate core, that is, a so-called coreless board. Of course, the gist can be applied.

The cross-sectional schematic diagram of the wiring board of this invention. FIG. 2 is a detailed cross-sectional view of the wiring board of FIG. 1. The top view and bottom view of the wiring board of FIG. FIG. 3 is an explanatory diagram of an assembly process of a semiconductor device using the wiring board of FIG. 1. FIG. 6 is an explanatory diagram of a wiring board workpiece forming process. The thickness direction projection figure which shows the positional relationship of a 1st support body and a 2nd support body. The figure following FIG. Sectional drawing which shows the specific example of the shaping | molding process of a wiring board workpiece | work. The top view which shows the other example of a 2nd support body. Sectional drawing which similarly shows the other example of a 2nd support body. The cross-sectional schematic diagram of the wiring board of 2nd embodiment. The top view of the wiring board of FIG. FIG. 12 is an explanatory diagram of an assembly process of a semiconductor device using the wiring board of FIG. 11. Sectional drawing which shows the specific example of the process of joining a reinforcing material to a wiring board workpiece | work. The figure explaining the problem of the conventional wiring board. The figure following FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Terminal pad 11 Solder bump 17 Back surface terminal pad 21 Board | substrate center part 23 Board | substrate outer peripheral part 25 Integrated circuit chip 27 1st support body 29,35,36 2nd support body (support body)
27h, 29h, 61h Through holes 40A, 40B, 40C, 40D Laminate 41 Substrate manufacturing apparatus 43 Flexible film 44 Vacuum chamber 61 Reinforcement material 100, 200 Wiring substrate (wiring substrate body)
100w, 200w wiring board workpieces 100p, 200p first main surface 100q, 200q second main surface

Claims (11)

  A wiring board using a resin as an insulating material, the central part of the board having terminals connected to the integrated circuit chip on the first main surface side, and the part outside the central part of the board, which is more than the central part of the board A wiring board comprising: a substrate outer peripheral portion having a shape inclined toward the first main surface side.   A wiring board using a resin as an insulating material, the board central part having a terminal connected to the integrated circuit chip on the first main surface side, a board outer peripheral part which is a part around the board central part, and the board A plate-shaped reinforcing member joined to the first main surface of the outer peripheral portion of the substrate so as to surround the plurality of terminals arranged in a lattice form in the central portion, and the outer peripheral portion of the substrate together with the reinforcing material A wiring board having a shape inclined to one main surface side.   The central portion of the substrate and the substrate for solder connection with another component such as a mother board on the second main surface side opposite to the first main surface side provided with the terminals to be connected to the integrated circuit chip The wiring board according to claim 1, further comprising a plurality of back surface terminals arranged in a lattice pattern over both the outer peripheral portion and the outer peripheral portion. Using a resin as an insulating material, a wiring board work including a substrate central portion having terminals connected to the integrated circuit chip on the first main surface side and a substrate outer peripheral portion that is a portion around the substrate central portion is manufactured. Process,
A first support having an opening for forming, on the first main surface, a space over which the entire central portion of the substrate faces when contacting the wiring substrate work from the first main surface side; and the wiring substrate work And a second support that forms a space on the second main surface that is wide enough to include the entire opening of the first support in the in-plane direction when contacted from the second main surface side. The first support body is configured such that the first support body contacts the substrate outer peripheral portion from the first main surface side, and the substrate outer peripheral portion is supported by the second support body from the second main surface side. And arranging the wiring board workpiece and the second support in this order in the board thickness direction;
The first support body is pressed from the side opposite to the side in contact with the wiring board workpiece while the outer peripheral portion of the board is supported by the second support body, and the wiring board workpiece is attached to the second main surface side. Forming the wiring board workpiece so that the outer peripheral portion of the substrate is inclined toward the first main surface while maintaining the flatness of the central portion of the substrate.
A method for manufacturing a wiring board, comprising: The first support is a frame-shaped plate-like body having through holes in the thickness direction for exposing the plurality of terminals arranged in a lattice form in the center of the substrate,
In the in-plane direction, the second support has a wide-opening that includes the entire inner peripheral edge forming the through hole of the first support, and a space that the entire center of the substrate faces is the second support. A plate-shaped body in the form of a frame formed on the main surface,
The step of forming the wiring board work includes biasing the wiring board work toward the second main surface side so as to sink the central portion of the board into the opening of the second support. 4. A method for producing a wiring board according to 4.   The step of forming the wiring board work includes a solder in which a laminate of the first support, the wiring board work, and the second support is disposed on a surface of the terminal of the wiring board work, or 6. The method for manufacturing a wiring board according to claim 4, wherein the method is carried out while heating at a temperature lower than the melting point of the solder constituting the terminal. Using a resin as an insulating material, a wiring board work including a substrate central portion having terminals connected to the integrated circuit chip on the first main surface side and a substrate outer peripheral portion that is a portion around the substrate central portion is manufactured. Process,
When coming into contact with the wiring board work from the first main surface side, it forms a frame shape having a through hole for exposing the plurality of terminals arranged in a lattice at the center of the board, and is joined to the outer peripheral part of the board A board-shaped reinforcing material and a space having an area including the entire inner peripheral edge forming the through hole of the reinforcing material in the in-plane direction when contacting the wiring board workpiece from the second main surface side. After preparing a support body to be formed on the second main surface side of the central portion, the reinforcing material is in a state where an adhesive containing a thermosetting resin is interposed between the reinforcing material and the wiring board work. The reinforcing material, the wiring board workpiece, and the substrate outer peripheral portion in surface contact from the first main surface side, the substrate outer peripheral portion is supported by the second support body from the second main surface side, Arranging the support in the thickness direction in this order;
The wiring board work is urged toward the second main surface side by pressing the reinforcing material from the side opposite to the side in surface contact with the wiring board work in a state where the outer peripheral portion of the board is supported by the support. And, the step of curing the adhesive while maintaining the energized state to join the wiring board work and the reinforcing material,
A method for manufacturing a wiring board, comprising: In the in-plane direction, the support has a wide-mouth through hole including the entire inner peripheral edge forming the through-hole of the reinforcing material, and a space desired by the entire central portion of the substrate is formed on the second main surface. A frame-shaped plate-like body formed in
In the step of joining the wiring board workpiece and the reinforcing material, the reinforcing material is pressed while supporting the outer peripheral portion of the substrate with the support body, and the central portion of the board sinks into the through hole of the support body. The method of manufacturing a wiring board according to claim 7, wherein the wiring board work is biased in the direction of the support body. The reinforcing member is in the form of a frame having a rectangular through hole, while the support is in the form of a frame having a circular through hole having a diameter larger than the diagonal line of the through hole of the reinforcing material,
In the in-plane direction, the reinforcing material, the wiring board work, and the inner peripheral edge forming the through hole of the reinforcing material are in a relative positional relationship within the inner peripheral edge forming the through hole of the support. 9. The method of manufacturing a wiring board according to claim 8, wherein the step of arranging the support in the thickness direction in this order is performed.   The step of joining the wiring board workpiece and the reinforcing material includes a step of soldering a laminate of the reinforcing material, the wiring board workpiece, and the support disposed on the surface of the terminal of the wiring board workpiece, or The method for manufacturing a wiring board according to claim 7, wherein the method is performed while heating at a temperature lower than a melting point of solder constituting the terminal and the adhesive is cured. A plate-like laminate in which the reinforcing material, the wiring board work, and the support are arranged in this order in the thickness direction in a vacuum chamber in which at least a part of the walls is formed of a flexible film, The reinforcing material is formed in a posture facing the flexible membrane,
By exhausting the inside of the vacuum chamber with the wiring board work supported by the support, bending the flexible film and pressing the reinforcing material at atmospheric pressure, the reinforcing material and the substrate outer periphery 11. The circuit board work is urged toward the second main surface side so as to sink the central portion of the substrate into the through-hole of the support body while maintaining the surface contact state. The manufacturing method of the wiring board of any one of these.

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