JP4267903B2 - Manufacturing method of multilayer wiring board - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a multilayer wiring board.
[0002]
[Prior art]
As a wiring board for mounting an electronic component such as a semiconductor chip, for example, there is a build-up wiring board. This build-up wiring board is manufactured by forming a build-up layer by laminating an insulating layer composed only of resin and a wiring layer for forming a wiring pattern on the surface (both sides or one side) of the core board. can do.
[0003]
However, an ordinary build-up wiring board has a build-up layer formed on a core substrate and is used as a product in a state in which the core substrate is formed, so that the thickness of the entire wiring board is increased. There's a problem. When the thickness as the wiring board is large, the wiring density is reduced as a result. In recent years when electronic components have been remarkably miniaturized, a wiring board having a higher wiring density is required. However, it is gradually becoming difficult to sufficiently meet such demands. In addition, the connection between the electronic components mounted on the wiring board and the operating power supply is made through this core board, so that the length of the wiring that connects the two is increased by the thickness of the core board. Degradation of characteristics is caused. Due to such problems, wiring boards having no core board are being proposed. However, in a wiring board that does not have a core board, the strength of the wiring board may be inferior, or handling properties during the manufacturing process may not be sufficiently maintained.
[0004]
On the other hand, in Japanese Patent Application Laid-Open No. 2002-26171 (Patent Document 1), a build-up layer is formed on a metal plate, and the metal plate is partially etched to expose the build-up layer. A technique for utilizing a metal frame made of a metal plate as a support frame for reinforcing the strength of the buildup layer is disclosed. FIG. 3 is a schematic diagram for briefly explaining the method disclosed in the publication. First, as shown in FIG. 3A, a buildup layer BU having an insulating layer and a wiring layer is formed on the metal plate 31. Next, as shown in FIG. 3B, by partially removing the metal plate 31, the surface of the buildup layer BU is exposed and the buildup layer BU is inverted so that the metal plate 31 remains. Is a support frame 32 for reinforcing the build-up layer BU. As a result, it is possible to manufacture a multilayer wiring board that has sufficient strength without having a core substrate and that can maintain sufficient handleability during the manufacturing process for forming the build-up layer BU. It becomes.
[0005]
[Patent Document 1]
JP 2002-26171 A [0006]
[Problems to be solved by the invention]
However, in the wiring board obtained by the method described in the above publication, an electronic component is mounted on the outermost surface 33 of the buildup layer exposed by etching the metal plate 31. The surface of the buildup layer BU When solder bumps for mounting electronic components are to be formed on the metal pad layer 34 formed on the side 33, it is necessary to form the solder bumps with the support frame 32 formed as shown in FIG. 3B. Therefore, there is a problem that the support frame 32 becomes an obstacle and it is difficult to form solder bumps. Further, not only when solder bumps for mounting electronic components are formed on the main surface of the buildup layer BU exposed after the metal plate 31 is partially removed, but before the connection metal layer is formed. Even when surface treatment such as Ni plating or Au plating is performed on the exposed surface of the metal pad layer 34, there are the above-mentioned problems.
[0007]
An object of the present invention is to provide a solder bump on a main surface of a buildup layer on a side where a support frame is formed in a method for manufacturing a multilayer wiring board having a buildup layer and a support frame without a core substrate. It is an object of the present invention to provide a method that facilitates surface treatment such as forming a connecting metal layer.
[0008]
[Means for solving the problems and actions / effects]
In order to solve the above problems, a method for manufacturing a multilayer wiring board according to the present invention includes a buildup layer that does not have a core substrate and includes an insulating layer and a wiring layer, and a support formed on the main surface of the buildup layer. A method of manufacturing a multilayer wiring board having a frame, comprising: forming an insulating layer on a metal substrate; forming a wiring layer on the insulating layer; and forming an interlayer insulating layer on the wiring layer. Forming a new wiring layer on the interlayer insulating layer, forming a buildup layer in which the interlayer insulating layer and the wiring layer are alternately stacked, and forming an insulating layer on the uppermost layer of the buildup layer. In the insulating layer, the metal substrate is removed leaving a step of forming an opening in a form in which a wiring layer formed under the insulating layer is exposed and a build-up layer formed on the metal substrate. And the build-up layer on the side where the metal substrate is removed In the insulating layer, an opening is formed in a form in which the wiring layer formed on the insulating layer is exposed, and a connection metal layer for connecting an electronic component to the opening in a form communicating with the wiring layer forming a look-containing and attaching the support frame body, a on the surface of the buildup layer of the connection metal layer is formed a side, after removing the metal substrate, the buildup layer Before the support frame is attached to the main surface on the side from which the metal substrate has been removed, solder bumps as the connection metal layer are formed .
The method for manufacturing a multilayer wiring board may include a step of forming solder balls for connecting to a mother board on a main surface opposite to the main surface on which the metal substrate is removed. it can.
A method for manufacturing a multilayer wiring board includes a build-up layer that does not have a core substrate and includes an insulating layer and a wiring layer, and a support frame formed on a main surface of the build-up layer. A method of forming an insulating layer on a metal substrate, forming a wiring layer on the insulating layer, forming an interlayer insulating layer on the wiring layer, and forming a new layer on the interlayer insulating layer. Forming a buildup layer in which the interlayer insulating layer and the wiring layer are alternately laminated, and forming an insulating layer on the uppermost layer of the buildup layer. Forming an opening in a form in which a wiring layer formed under the substrate is exposed; removing the metal substrate while leaving a buildup layer formed on the metal substrate; and removing the metal substrate The insulating layer of the build-up layer on the finished side A step of forming an opening in a form in which the formed wiring layer is exposed, and a connecting metal layer for mounting electronic components on the main surface opposite to the main surface from which the metal substrate has been removed. And a step of attaching a support frame on the surface of the buildup layer on the side on which the connection metal layer is formed, and after removing the metal substrate, the metal of the buildup layer Solder bumps as the connection metal layer may be formed on the main surface opposite to the main surface from which the substrate has been removed before attaching the support frame.
In addition, the method for manufacturing a multilayer wiring board may include a step of forming solder balls for connection to the mother board on the main surface on the side from which the metal substrate has been removed .
[0009]
According to the method of the present invention as described above, a method is adopted in which the metal substrate is completely removed and then the support frame is reattached so that the metal substrate is not used as the support frame. Therefore, since the metal substrate does not remain on the main surface of the buildup layer, it becomes easy to perform surface treatment on the main surface after the metal substrate is removed. In addition, since it is not necessary to leave the metal substrate intentionally, it is not necessary to perform a special treatment for partially removing the metal substrate. Specifically, there is an effect that it is not necessary to use a mask or the like for partially leaving the metal substrate.
[0010]
In addition , the present invention provides a metal layer for connection for connecting an electronic component before the support frame is attached to the main surface of the buildup layer on the side where the metal substrate is removed after removing the metal substrate . By forming solder balls as solder bumps and solder balls as connection metal layers to connect to the motherboard , that is, the main surface of the buildup layer from which the metal substrate has been removed is placed on the electronic component mounting side and the motherboard. It will be set as the main surface on the mounting side . According to such a method, solder bumps are formed on the surface of the build-up layer when manufacturing a multilayer wiring board having no core substrate, in which a support frame for reinforcing the multilayer wiring board has to be disposed. It becomes easy to form a metal layer for connection. In other words, during the manufacturing process, the metal substrate for improving the handleability of the build-up layer is not used for the support frame, but the metal substrate is completely removed and a new support frame is attached to the build-up layer. A connection metal layer was formed before partially forming on the surface. According to this, in forming the connection metal layer for mounting the electronic component, the remaining metal substrate (support frame) does not get in the way, so the connection metal layer can be easily formed. Further, since there is no metal substrate that obstructs the formation of the connection metal layer, the connection metal layer can be formed at a desired position with high accuracy.
[0011]
Furthermore, when the manufacturing method of the present invention is adopted, the step of removing the metal substrate is performed by an etching process, and when forming the buildup layer on the metal substrate , a solder resist on the metal substrate is used. A certain insulating layer is preferably formed as an etch stop layer when the metal substrate is etched . According to this, when the metal substrate is removed by etching, the etch stop layer can prevent the wiring layer as the buildup layer from being etched together. As an etch stop layer, it is natural to use a layer that is resistant to an etchant for etching a metal substrate . Furthermore, in order to prevent the wiring layer from being removed when the metal substrate is etched, an etch stop layer may be formed separately from the buildup layer. A method may be adopted. That is, the buildup layer is formed such that the insulating layer or the metal layer of the buildup layer is directly above the metal substrate , and the insulating layer or the metal layer also serves as the etch stop layer. An insulating layer, which is essential as a buildup layer, is first formed on a metal substrate and used as an etch stop layer, so that it is not necessary to form the etch stop layer separately from the buildup layer. Therefore, it is possible to expect the improvement of manufacturing efficiency and cost reduction.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 illustrates an example of the method for manufacturing a multilayer wiring board according to the present invention. In the method shown in FIG. 1, first, as shown in Step A, an insulating layer 2 (thickness of about 30 μm) of the build-up layer is formed on a metal substrate 1 (thickness of about 150 μm), and an insulating film is formed. Laminate to form. As a material of the metal substrate 1, for example, Cu, Cu alloy, SUS (JIS standard), Fe—Ni alloy, Al, Al alloy, Invar, Invar alloy, or the like can be used. As a material of the insulating layer 2, a known photosensitive resin or thermosetting resin such as polyimide or epoxy resin can be employed. The thickness of the metal substrate can be about 100 μm to 500 μm.
[0013]
After forming the insulating layer 2 on the metal substrate 1 as described above, the metal pad layer 3 (thickness as a wiring layer of the buildup layer) is formed on the insulating layer 2 as shown in Step B of FIG. About 15 μm). The metal pad layer 3 is formed in a desired wiring pattern by a known method. For example, a metal film to be the metal pad layer 3 may be uniformly formed on the insulating layer 2 and then unnecessary regions of the metal film may be removed by etching or the like so as to correspond to the wiring pattern. Then, after forming a plating resist layer having an opening corresponding to the wiring pattern on the insulating layer 2, a metal film may be formed only in the opening of the plating resist layer to form the metal pad layer 3. In addition, as a material of the metal pad layer 3, Cu which is inexpensive and has low electric resistance can be employed.
[0014]
Next, as shown in Step C, an interlayer insulating layer 4 as an insulating layer of the buildup layer is formed on the metal pad layer 3. As a method for forming the interlayer insulating layer 4, a method suitable for the material of the interlayer insulating layer 4 can be employed. For example, it can be formed by laminating a film-like resin. Then, a via hole 5 is formed in the formed interlayer insulating layer 4. The via hole 5 can be formed by a laser, for example. As the laser, for example, an excimer laser, a carbon dioxide laser, a YAG laser, or the like can be used. When the method of forming the via hole 5 with a laser is employed, a thermosetting resin such as polyimide or epoxy resin is used as the material of the interlayer insulating layer 4. A resin layer made of a thermosetting resin is cured by a curing process to form an interlayer insulating layer 4, and then a via hole 5 is formed by irradiating a laser. It is also possible to employ a photosensitive resin as the material of the interlayer insulating layer 4 and form the via hole 5 by a photo via method without using a laser.
[0015]
Then, as shown in step D, a via conductor 6 as a wiring layer is formed in the formed via hole 5. The via conductor 6 can be formed by, for example, electrolytic plating or electroless plating. Then, a new wiring layer is formed on the interlayer insulating layer 4 so as to communicate with the via conductor 6. The buildup layer BU can be formed by alternately laminating such interlayer insulating layers 4 and wiring layers. Further, a solder resist layer 9 as an insulating layer is formed on the uppermost layer of the build-up layer BU, and a desired pattern is formed at a predetermined position of the solder resist layer 9 immediately below the solder resist layer 9. The opening 8 is formed in such a manner that the metal pad layer 7 as the wiring layer is exposed. The insulating layer 2 formed immediately above the metal substrate 1 constitutes the solder resist layer 2 opposite to the solder resist layer 9 of the multilayer wiring board obtained by the manufacturing method of the present invention.
[0016]
Next, as shown in step E, the metal substrate 1 is completely removed leaving the build-up layer BU formed on the metal substrate 1. As a method for removing the metal substrate 1, an etching process can be employed. Alternatively, a method may be employed in which after the metal substrate 1 is removed to a certain thickness by grinding, the remaining portion of the metal substrate 1 is removed by etching. However, when the metal substrate 1 is to be removed by a mechanical method such as grinding, an undesired external force is applied to the buildup layer BU, and a defective portion such as a crack may be formed in the buildup layer BU. There is also. Therefore, it can be said that it is desirable that the metal substrate 1 be removed only by etching without performing mechanical grinding because a high-quality multilayer wiring substrate can be obtained. When an etching process is employed as a method for removing the metal substrate 1, the insulating layer 2 (solder resist layer 2) formed immediately above the metal substrate 1 functions as an etch stop layer for the etching process. Therefore, it is possible to prevent the metal pad layer 3 made of the same metal from being removed along with the etching process of the metal substrate 1. Furthermore, since it is not necessary to provide an etch stop layer separately from the buildup layer, the manufacturing process can be simplified.
[0017]
After removing the metal substrate 1 while leaving the buildup layer BU, as shown in Step F, the buildup layer BU is inverted, and an opening is formed so that the metal pad layer 3 is exposed in the insulating layer 2. Since the opening is formed in the insulating layer 2 that has already been cured, it is desirable that the opening be formed by a laser. Then, as shown in Step G, solder bumps 10 as connection metal layers are formed in the formed openings so as to communicate with the metal pad layer 3. Next, after forming the buildup layer BU, as shown in Step H, the support frame 11 is attached on the surface of the buildup layer BU on the side where the solder bumps 10 are formed. Thus, in the present invention, after completely removing the metal substrate 1 on which the build-up layer BU is formed, the support frame 11 for reinforcing the strength of the build-up layer BU is formed on the build-up layer BU. Since the solder bump 10 (connection metal layer) is formed before the mounting, the step of forming the solder bump 10 can be performed more easily.
[0018]
In the present embodiment, the electronic component is mounted on the surface of the multilayer wiring board manufactured as described above on the side where the solder bumps 10 and the support frame 11 are formed. A solder ball (not shown) is formed in a form communicating with the metal pad layer 7 exposed on the main surface opposite to the side on which the solder bump 10 is formed, and the multilayer wiring board is attached to the mother board or the like via the solder ball. Will be installed.
[0019]
As a material of the solder bump 10 formed on the main surface of the buildup layer, a normal material can be used. For example, an alloy made of a low melting point alloy such as Sn—Ag, Pb—Sn, Sn—Ag—Cu, Sn—Cu, or Sn—Zn can be used.
[0020]
Furthermore, the manufacturing method of the multilayer wiring board of the present invention can also be performed by a method as shown in FIG. In the method shown in FIG. 2, first, in step A ′, the plating resist 12 is formed on the metal substrate 22. The plating resist 12 can be formed by laminating a film-like photosensitive resin on the metal substrate 22, and selectively exposing and developing. As the material of the metal substrate 22, the same material as that of the embodiment described with reference to FIG. 1 can be employed. Next, as shown in step B ′, a metal layer 14 as an etch stop layer is formed on the surface of the metal substrate 22 not covered with the plating resist 12. As a material of the metal layer 14 as the etch stop layer, a material that is not etched together with the metal substrate 22 when the metal substrate 22 is removed by etching is selected in a process described later. For example, when the metal substrate 22 is made of SUS, Au can be adopted as the material of the metal layer 14, while when the metal substrate 22 is made of Cu, the metal layer Ni can be adopted as the material of 14. Note that the metal layer 14 may be composed of not only one layer but also a plurality of layers. The thickness of the metal layer 14 can be set to about 5 μm to 20 μm.
Next, a metal pad layer 13 as a wiring layer is formed on such a metal layer 14. The metal pad layer 13 can be formed, for example, by electrolytic plating. As a material of the metal pad layer 13, for example, Cu can be adopted. The metal layer 14 is for preventing the metal pad layer 13 from being removed when the metal substrate 22 is removed by etching. Therefore, the metal pad layer 13 is removed when the metal substrate 22 is etched. If the materials of the metal substrate 22 and the metal pad layer 13 are selected so that the metal layer 14 is not required, the metal layer 14 need not be formed. In the case of the present embodiment, the metal layer 14 functions as an etch stop layer, and also functions as a metal pad layer for mounting electronic components together with a metal pad layer 13 described later.
[0021]
Next, as shown in step C ′, the plating resist 12 is removed. Thereafter, as shown in step D ′, the buildup layer BU is formed by the same method as in FIG. Specifically, an interlayer insulating layer 16 is formed on the metal layer 14 and the metal pad layer 13 formed on the metal substrate 22, and via holes are formed at positions corresponding to the metal pad layer 13 of the interlayer insulating layer 16. After the formation, the step of forming the via conductor 15 as a wiring layer in the via hole is sequentially performed. As a method for forming the interlayer insulating layer 16, a method similar to that of the embodiment described with reference to FIG. 1 can be employed. Further, the via hole may be formed by a laser or may be formed by a photo via method. Further, similarly to the method described with reference to FIG. 1, the uppermost layer of the buildup layer BU is a solder resist layer 17. A metal pad layer 19 is formed immediately below the solder resist layer 17, and an opening 18 is formed in the solder resist layer 17 so that the metal pad layer 19 is exposed. In the case of the present embodiment, the metal pad layer 19 formed on the side opposite to the metal substrate 22 is a metal pad layer for mounting the multilayer wiring board obtained by the method of the present invention on the mother board. The metal pad layer 13 is a metal pad layer for mounting electronic components. Therefore, the metal pad layer 13 is formed smaller than the metal pad layer 19.
[0022]
And after forming buildup layer BU as mentioned above, as shown to process E ', the metal substrate 22 is removed completely. The method for removing the metal substrate 22 may be the same as the method described in FIG. At this time, when the metal layer 14 is formed, the metal layer 14 functions as an etch stop layer, and even when the metal substrate 22 and the metal pad layer 13 are made of the same material (for example, Cu), the metal pad 14 It is possible to prevent the layer 13 from being removed.
[0023]
Subsequently, the buildup layer BU from which the metal substrate 22 has been removed is inverted, and in step F ′, solder bumps 20 are formed on the metal pad layer 13 (metal layer 14), and thereafter, in step G ′. As shown, the support frame 21 is attached to the main surface of the buildup layer BU on the side where the solder bumps 20 are formed. As the material of the support frame 21, the same method as described in FIG. 1 can be employed. Thus, since the solder bumps 20 are formed after the metal substrate 22 is completely removed and before the support frame 21 is attached, the solder bumps 20 can be formed more easily.
[0024]
In the method for manufacturing a multilayer wiring board according to the present invention, when forming the solder bumps 10 and 20 on the main surface of the build-up layer BU, the material of the solder bumps 10 and 20 is applied onto the build-up layer BU. This is particularly effective when a method of applying by a printing method is employed. That is, when the solder bumps 10 and 20 are formed by the printing method, it is necessary to dispose a mask having a pattern corresponding to the formation position of the solder bumps 10 and 20 on the buildup layer BU. However, in the method of partially removing the metal substrate and utilizing the remaining portion of the metal substrate as a support frame as shown in the prior art, this mask is used to form the solder bumps of the buildup layer BU. It becomes difficult to arrange on the side surface. However, even if the mask is arranged, a gap is generated between the build-up layer and the mask, and the solder bump cannot be formed with high accuracy. On the other hand, in the present invention, the solder bump is formed in a state where the metal substrate is completely removed. Therefore, the printing method can be adopted without any problem when forming the solder bump.
[0025]
Furthermore, in the above embodiment of the present invention, the electronic component is mounted on the main surface of the buildup layer on the side where the metal substrate is removed, but the present invention is not limited to this. . For example, the main surface of the build-up layer on the side from which the metal substrate has been removed is the main surface on the side facing the motherboard when the multilayer wiring board itself obtained by the method of the present invention is mounted on the motherboard or the like. Is also possible. In this case, after the metal substrate is completely removed from the buildup layer, a connection metal layer (for example, a solder ball) for connection to the mother board is formed on the main surface on the side from which the metal substrate has been removed. Then, a metal layer for connection (for example, solder bumps) for mounting the electronic component is formed on the main surface opposite to the main surface from which the metal substrate has been removed, and then the electronic component is mounted. A support frame is attached to the main surface on the side where the connecting metal layer is formed.
[Brief description of the drawings]
FIG. 1 illustrates one embodiment of the present invention.
FIG. 2 is a diagram illustrating an embodiment different from FIG. 1 of the present invention.
FIG. 3 is a diagram for explaining a conventional method of manufacturing a wiring board.
1,22 Metal substrate 2, 9, 17 Insulating layer (solder resist layer)
3, 7, 13 Wiring layer (metal pad layer)
4, 16 Insulating layer (interlayer insulating layer)
6, 15 Wiring layer (via conductor)
10, 20 Solder bump (metal layer for connection)
11, 21 Support frame BU Build-up layer

Claims (6)

A method for producing a multilayer wiring board having no core substrate and having a build-up layer including an insulating layer and a wiring layer, and a support frame formed on the main surface of the build-up layer,
Forming an insulating layer on the metal substrate;
A wiring layer is formed on the insulating layer, an interlayer insulating layer is formed on the wiring layer, a new wiring layer is formed on the interlayer insulating layer, and the interlayer insulating layer and the wiring layer are alternately stacked. Forming a build-up layer;
Forming an insulating layer on the top layer of the build-up layer, and forming an opening in the insulating layer in a form in which a wiring layer formed under the layer is exposed;
Leaving the build-up layer formed on the metal substrate, removing the metal substrate;
An opening is formed in the insulating layer of the build-up layer on the side from which the metal substrate has been removed in such a manner that the wiring layer formed thereon is exposed, and the opening communicates with the wiring layer. Forming a connecting metal layer for connecting electronic components in a form to
Attaching a support frame on the surface of the build-up layer on the side on which the connection metal layer is formed;
Including
After removing the metal substrate, before attaching the support frame to the main surface of the build-up layer on the side where the metal substrate is removed, solder bumps are formed as the connection metal layer.
A method for manufacturing a multilayer wiring board. Forming a solder ball for connecting to a mother board on a main surface opposite to the main surface from which the metal substrate has been removed,
  The method for producing a multilayer wiring board according to claim 1. A method for producing a multilayer wiring board having no core substrate and having a build-up layer including an insulating layer and a wiring layer, and a support frame formed on the main surface of the build-up layer,
  Forming an insulating layer on the metal substrate;
  A wiring layer is formed on the insulating layer, an interlayer insulating layer is formed on the wiring layer, a new wiring layer is formed on the interlayer insulating layer, and the interlayer insulating layer and the wiring layer are alternately stacked. Forming a build-up layer;
  Forming an insulating layer on the top layer of the build-up layer, and forming an opening in the insulating layer in a form in which a wiring layer formed under the layer is exposed;
  Leaving the build-up layer formed on the metal substrate, removing the metal substrate;
  Forming an opening in the form of exposing the wiring layer formed on the insulating layer of the build-up layer on the side where the metal substrate has been removed;
  Forming a connection metal layer for mounting an electronic component on the main surface opposite to the main surface from which the metal substrate has been removed;
Attaching a support frame on the surface of the buildup layer on the side where the connection metal layer is formed;
  Including
  After removing the metal substrate, before attaching the support frame to the main surface of the buildup layer opposite to the main surface from which the metal substrate has been removed, solder bumps as the connection metal layer Forming,
  A method for manufacturing a multilayer wiring board. Forming a solder ball for connecting to a mother board on the main surface on the side from which the metal substrate has been removed,
The method of manufacturing a multilayer wiring board according to claim 3.   The step of removing the metal substrate is performed by an etching process, and when the metal substrate is etched with an insulating layer on the metal substrate formed when the build-up layer is formed on the metal substrate. 5. The method for manufacturing a multilayer wiring board according to claim 1, wherein the etching stop layer is formed as follows. Method for manufacturing a multilayer wiring board according to any one of claims 1 to 5, characterized in that the insulating layer on the metal substrate is a solder resist.

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