JP2004031738A - Wiring board and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wiring board which is as high in board strength as required and includes a core board where through-holes can be easily bored and that is provided with a flat front surface and a flat rear surface and to provide a method of manufacturing the same. <P>SOLUTION: The wiring board 36 comprises the core board 1 comprising metal plates 2 and 6 which are provided with front surfaces 3 and 7 and rear surfaces 4 and 8 and arranged in parallel with each other through an insulating material 10, the through-holes 5 and 5 which are bored in the metal plates 2 and 6 as penetrating through parts between the surfaces 3 and 7 and the rear surfaces 4 and 8 and formed at the same positions in a plan view, and the insulating material 10 filling the through-holes 5 and 5. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a wiring board using a core substrate having a core material (core material) of a metal plate and a method of manufacturing the same.
[0002]
[Prior art]
As a wiring substrate having a multilayer structure including a plurality of insulating layers and a plurality of wiring layers located therebetween, a resin or resin-glass insulating core substrate is used. However, in order to increase the strength of the wiring board and prevent deformation such as warpage, a core board having a metal plate made of, for example, a copper alloy is also used.
As shown in FIG. 6A, such a metal core substrate 60 is made of a copper plate made of a copper alloy and having a thickness of 0.25 mm, and a through hole 65 penetrating between a front surface 63 and a back surface 64 thereof. And an insulating material 66 made of a synthetic resin filled in the through hole 65. On the front surface 63 and the back surface 64 of the metal plate 62, insulating layers 66a and 66b made of synthetic resin are individually formed.
[0003]
When importance is placed on the heat dissipation of the wiring board, the used current value and the board strength, a relatively thick metal plate 62 is used. However, as shown in FIG. 6B, when the through hole 65 is formed between the front surface 63 and the back surface 64 of the metal plate 62, the ratio (aspect ratio) between the axial length and the inner diameter of the through hole 65 Ratio) increases. For this reason, there has been a problem that it is difficult to accurately form the through hole 65 using a drill or the like.
On the other hand, a relatively thin metal plate 62 is used in the core board 60 of the wiring board that is compatible with miniaturization and thinning, and emphasizes the reduction of loop inductance in the through-hole conductor penetrating the inside. However, when the core substrate 60 having the thin metal plate 62 is used, there is a problem that the substrate strength is reduced.
[0004]
Further, as shown in FIG. 6C, the wiring board 70 in which the build-up layer BU is formed only on the front surface 67 side (one side) of the core substrate 60 has the following structure.
As shown in FIG. 6 (C), the wiring board 70 has a through-hole conductor 72 and a filling hole 65 formed in the through-hole 65 of the metal plate 62 in the core board 60 through an insulating material 66. The resin 73 is formed. On the front surface 67 and the back surface 68 of the core substrate 60, a front surface wiring layer 74 and a back surface wiring layer 75 are individually formed. Further, the build-up layer BU has insulating layers 76 and 82 made of resin and wiring layers 80 and 86 formed therebetween. The wiring layer 80 is formed via the surface wiring layer 74 and the via conductor 78. The wiring layers 80 and 86 are connected by a via conductor 84.
[0005]
As shown in FIG. 6C, an uppermost insulating layer (solder resist layer) 88 is formed on the insulating layer 82 and the wiring layer 86, and a plurality of solder bumps 92 erected from the wiring layer 86 are formed. , Penetrate the insulating layer 88 and protrude higher than the surface 90 thereof. As shown in FIG. 6C, an insulating layer (solder resist layer) 79 is also formed below the back surface 68 and the back surface wiring layer 75 of the core substrate 60, and a plurality of openings formed on the surface 81. In 83, a wiring 77 extending from the back wiring layer 75 is located.
[0006]
However, when the metal plate 62 in the core substrate 60 is thick and the through hole 65 is long, the amount of the insulating material 66 filled in the wiring substrate 70 is increased. Is formed on the front surface 67 and the back surface 68 of the core substrate 60 located at the position, and the flatness of the wiring layer 74 formed thereon cannot be obtained. Further, when the length of the through hole 65 is increased, there is a problem that the loop inductance of the through hole conductor 72 penetrating the through hole 65 increases.
In addition, since the resin is unevenly distributed on the side of the build-up layer BU and the metal is unevenly distributed on the side of the core substrate 60, the entire wiring substrate 70 is entirely built-up layer BU as shown by a dashed line in FIG. There is also a problem that warpage such as dent on the side is likely to occur.
[0007]
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION The present invention solves the problems in the conventional technique described above, and provides a wiring board having a high board strength, including a core board having a flat front surface and a flat back surface, in which a through hole is easily formed, and a method of manufacturing the same. To do.
[0008]
Means for Solving the Problems and Effects of the Invention
The present invention has been made with the idea of using a plurality of relatively thin metal plates for a core substrate in order to solve the above problems.
That is, a wiring board of the present invention (claim 1) has a plurality of metal plates having a front surface and a back surface and arranged in parallel with each other with an insulating layer interposed therebetween. A core substrate including a penetrating through hole and an insulating material formed in the through hole is provided.
[0009]
According to this, since a plurality of relatively thin metal plates can be used, an accurate through-hole is formed between the front surface and the back surface, and the strength of the core substrate is not reduced and The strength of the wiring board including such a core board can be easily maintained at a desired level. Further, the weight can be reduced as compared with a conventional core substrate having one metal plate or a wiring substrate including the same. Further, the workability at the time of forming the through hole is improved as compared with the case where one relatively thick metal plate is used for the core substrate.
[0010]
In addition, by making the characteristics such as the coefficient of thermal expansion and the thickness of the plurality of metal plates different from each other, it is possible to suppress or eliminate the warpage caused by the internal structure of the wiring board having the multilayer structure. It is also possible.
The metal plate includes a copper alloy such as Cu-2.3 wt% Fe-0.03 wt% P (194 alloy), pure copper, oxygen-free copper, Fe-42 wt% Ni (42 alloy), and Fe-36 wt%. Plates made of Fe—Ni alloys such as Ni (invar), other steel types, titanium and its alloys, and aluminum and its alloys are included. The “relatively thin” refers to, for example, that the thickness is smaller than a conventional metal plate having a thickness of 0.25 mm.
[0011]
The present invention also includes a wiring board (Claim 2) in which the through-hole is formed at substantially the same position in plan view of the plurality of metal plates.
According to this, since the through-holes of the plurality of metal plates are located substantially coaxially, the through-hole conductor can be accurately arranged along the center thereof, and electrical characteristics such as insulation around the through-hole conductor can be obtained. Can be stabilized. Therefore, a highly reliable wiring board having required substrate strength and flatness can be obtained.
[0012]
Further, in the present invention, a front surface wiring layer and a back surface wiring layer formed on the front surface and the back surface of the core substrate, a plurality of insulating layers formed above at least one of the front surface wiring layer and the back surface wiring layer, and And a build-up layer including a plurality of wiring layers located therebetween.
According to this, it is possible to provide a wiring board having a multilayer structure having required board strength and flatness. Note that, for example, in a single-sided wiring board in which the build-up layer is formed only above the surface of the core substrate, by changing the coefficient of thermal expansion and the thickness of the plurality of metal plates included in the core substrate, It is possible to eliminate or suppress the warpage of the build-up layer on the side of the build-up layer, and to easily provide a build-up layer including a flatter wiring layer and an insulating layer, and a highly reliable wiring board having flat front and rear wiring layers.
[0013]
Further, the present invention may include a wiring board in which a through-hole conductor connecting the front wiring layer and the back wiring layer is formed in a through hole of the core substrate.
In this case, the through-hole conductor penetrates the through-holes of the plurality of metal plates via an insulating material, and can reliably ensure conduction between the front surface wiring layer and the back surface wiring layer. For this reason, a plurality of wiring layers in the build-up layer formed on at least one of the front surface and the back surface of the core substrate are electrically connected to the back wiring layer or the front surface wiring layer on the opposite side of the core substrate, or the build-up sandwiching the core substrate is performed. It is possible to ensure conduction between the up wirings.
[0014]
On the other hand, a first method of manufacturing a wiring board according to the present invention (Claim 4) includes a step of inserting an insulating sheet between a plurality of parallel metal plates having a front surface and a back surface and closely attaching the insulating sheet as an insulating layer; Forming a through-hole along the thickness direction of the laminate comprising the board and the insulating layer sandwiched therebetween, and laminating outer insulating sheets on the front and back surfaces of the laminate, respectively, And a step of filling the through-hole with an insulating material while pressing along and closely contacting the core substrate.
According to this, the through-hole can be formed in a plurality of metal plates with high precision, and the through-hole can be filled with an insulating material without excess or shortage, and a core substrate having a required strength, and a desired substrate using the same It is possible to reliably manufacture a wiring board having strength and flatness and stable electric characteristics.
[0015]
Also, a second method of manufacturing a wiring board according to the present invention (claim 5) includes a step of forming a through-hole at the same position in plan view on a plurality of metal plates having a front surface and a back surface, By inserting an insulating sheet between a plurality of parallel metal plates and pressing them along the thickness direction, a laminated body including an insulating layer closely contacted between the plurality of metal plates and an insulating material filled in the through holes is formed. And a step of bonding an outer insulating sheet to the front and back surfaces of the laminate, respectively.
This also allows the through-holes to be accurately formed in a plurality of metal plates, filling the through-holes with an insulating material without excess and deficiency, and a core substrate having a required strength and a flat and electrical characteristic using the core substrate. It is possible to reliably manufacture a stable wiring board.
[0016]
Incidentally, the present invention comprises, after each of the steps, a step of forming a through-hole and a through-hole conductor in the through-hole of the laminate and through the insulating layer, the surface insulating layer, and the back surface insulating layer, It can also include a method for manufacturing a wiring board.
In this case, since the through-hole conductor can be accurately arranged along the center of the through-hole of the plurality of metal plates, it has a required substrate strength and has excellent electrical characteristics such as insulation around the through-hole conductor. It is possible to manufacture a wiring board that has been manufactured.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings.
FIG. 1A shows a cross section of a core substrate 1 according to one embodiment of the present invention.
As shown in FIG. 1A, the core substrate 1 includes a pair (plurality) of metal plates (core materials) 2, 6, an insulating layer 10 interposed therebetween, and a surface 3 of the metal plates 2, 6. , 7 and the back surfaces 4, 8, a plurality of through holes 5, insulating materials 10 a, 10 b filled in the through holes 5, and a surface insulating layer formed on the front surface 3 of the metal plate 2 ( An outer insulating layer 9a and a back insulating layer (outer insulating layer) 9b formed on the back surface 8 of the metal plate 6 are provided.
The metal plates 2 and 6 are made of a copper alloy of Cu-2.3 wt% Fe-0.03 wt% P (194 alloy), and have a thickness of 0.1 mm, which is relatively thin as compared with the prior art.
[0018]
The through hole 5 has a circular cross section and an inner diameter of about 0.3 mm, and is formed by punching, drilling, or etching the metal plates 2 and 6. As shown in FIG. 1A, the plurality of through holes 5 are formed at the same position in plan view. Further, the insulating layer 10, the insulating materials 10a and 10b, the front insulating layer 9a, and the back insulating layer 9b are made of, for example, epoxy resin. Among them, the thickness of the insulating layer 10 and the front / back surface insulating layers 9a and 9b is about 20 to 40 μm.
That is, the core substrate 1 shown in FIG. 1A has an overall thickness between the front surface 11 and the back surface 12 of about 0.3 mm, and the processability of the through hole 5 is improved.
[0019]
According to the core substrate 1 as described above, the pair of relatively thin metal plates 2 and 6, the insulating layer 10 disposed therebetween, and the front surface 3 and the rear surface 8 of the metal plates 2 and 6 are formed. Because of the laminated structure composed of the front and back insulating layers 9a and 9b, the strength is not reduced as compared with the conventional core substrate 60 using a single metal plate 62. In addition, since the through-holes 5 having smooth inner walls are formed in the relatively thin metal plates 2 and 6, the insulating materials 10a and 10b are filled into the through-holes 5 and 5 without excess or shortage. In addition, since the amount of the insulating materials 10a and 10b filled in the through holes 5 and 5 is smaller than that of the related art, the surface 11 and the back surface 12 of the core substrate 1 directly above and below the recess are less likely to be formed. In this case, the wiring layer and the insulating layer to be formed later can be made flat.
[0020]
FIG. 1B shows a cross section of a wiring board 36 using the core board 1.
As shown in FIG. 1B, the wiring board 36 extends along the core board 1 and the through-holes 13 penetrating the center portions of the insulating members 10a and 10b located in the through-holes 5 and 5 and the inner wall thereof. Through-hole conductors 14, and a front surface wiring layer 16 and a back surface wiring layer 17 individually formed on the front surface 11 and the back surface 12 of the core substrate 1. The metal plates 2 and 6 can be used as a power supply or a ground layer by being electrically connected to the front wiring layer 16 and the rear wiring layer 17 via via conductors (not shown).
The through-hole conductor 14 has an outer diameter of about 150 μm and a thickness of about 20 μm, and is connected to the upper surface wiring layer 16 and the lower surface wiring layer 17 at the upper and lower ends. The front surface wiring layer 16 and the rear surface wiring layer 17 are formed of a copper plating film having a predetermined pattern and a thickness of about 10 to 40 μm.
[0021]
As shown in FIG. 1B, above the surface 11 and the surface wiring layer 16 of the core substrate 1, insulating layers 18 and 24 and wiring layers 22 and 28 formed between and on the surface are formed. A build-up layer BU is formed. The insulating layers 18 and 24 are made of an epoxy resin film having a thickness of 30 μm and containing an inorganic filler such as a silica filler. Each of the wiring layers 22 and 28 has a predetermined pattern and is made of a copper plating film having the same thickness as that described above. The wiring layers 22 and 28 and the surface wiring layer 16 and the wiring layer 22 are connected via via conductors (filled vias) 20 and 26 made of copper plating. On the insulating layer 24 and the wiring layer 28, an insulating layer (solder resist layer) 30 having a thickness of 20 μm is formed.
[0022]
Further, as shown in FIG. 1 (B), a plurality of solder bumps 32 penetrate through the insulating layer 30 and are higher than the first main surface 34 which is the surface of the wiring layer 28 from an appropriate position of the wiring layer 28. The solder bump 32 is made of a low melting point alloy such as Sn-Ag, Pb-Sn, Sn-Ag-Cu, Sn-Cu, or Sn-Zn (in this embodiment, Sn-Ag). It is individually connected to a connection terminal (not shown) of an IC chip (electronic component) 38 mounted on the main surface 34. The solder bumps 32 and the connection terminals of the IC chip 38 are buried and protected by an underfill material (not shown).
[0023]
On the other hand, as shown in FIG. 1B, an insulating layer (solder resist layer) 19 similar to the above is formed below (above) the back surface 12 and the back wiring layer 17 of the core substrate 1. The wiring 21 extending from the back wiring layer 17 is located on the bottom surface of the opening 23 that opens to the second main surface 25 side. The surface of the wiring 21 is coated with Ni plating and Au plating, and is used as a connection terminal to a printed circuit board such as a motherboard (not shown).
[0024]
In the wiring board 36 as described above, since the pair of metals 2 and 6 are relatively thin and arranged in parallel on the core board 1, the board has the same substrate strength as the conventional one and the through-hole 5 is formed with high precision. Therefore, the inside is filled with the insulating materials 10a and 10b densely, and the periphery of the through-hole conductor 14 can be reliably insulated. Further, since the surface 11 of the core substrate 1 is flat, it is easy to secure the flatness of the surface wiring layer 16 and the insulating layer 18 and the like formed thereabove. Further, since the through-hole conductor 14 penetrates the thin core substrate 1 including the relatively thin metal 2 and 6, the length of the through-hole conductor 14 is longer than that of a conventional case using a single thick metal plate. Becomes shorter by about several tens of μm. As a result, the loop inductance due to the current flowing through the through-hole conductor 14 can be reduced, and the electrical characteristics can be stabilized. Accordingly, the wiring board 36 has the same strength as the conventional one and can be reduced in weight, and the internal wiring and the like are flat and the electric characteristics are easily stabilized.
[0025]
Hereinafter, a method for manufacturing the wiring board 36 will be described.
FIG. 2 relates to a method (claim 4) for manufacturing the first wiring board 36 according to the present invention. FIG. 2A shows a state in which an insulating sheet S having a thickness of 60 μm is inserted between the back surface 4 and the front surface 7 of the pair of metal plates 2 and 6 made of the copper alloy and having a thickness of 0.1 mm. The process which pressed along the direction and made it contact closely is shown. As the insulating sheet S, for example, a dry type film made of an epoxy resin is used.
Next, as shown in FIG. 2 (B), through holes 5, h having an inner diameter of 0.3 mm are formed by drilling or punching along the thickness direction of the laminate including the metal plates 2, 6 and the insulating sheet S. A step of forming a plurality is performed. At this time, since the thickness of each of the metal plates 2 and 6 is as thin as 0.1 mm, the through holes 5 and h penetrating the metal plates 2 and 6 have good positional accuracy and a relatively smooth inner wall. Or it becomes a fracture surface.
[0026]
Next, as shown in FIG. 2 (C), a 60 μm-thick, similar to the above, is formed on the front surface 3 and the back surface 8 of the laminated body including the metal plates 2 and 6 having the plurality of through holes 5 and h and the insulating sheet S. The outer insulating sheets S1 and S2 are individually laminated. Then, as shown by arrows in FIG. 2 (C), a step of pressing the metal plates 2, 6, the insulating sheet S, and the outer insulating sheets S1, S2 while heating them by a hot press or the like along the thickness direction. Do. After such a step, a known curing process of heating and curing the insulating sheets S, S1, and S2 is performed.
As a result, as shown in FIG. 2 (D), the insulating sheets S, S1, S2 are compressed in the thickness direction, and some of them are pressed into the through holes 5, 5 of the metal plates 2, 6. To form insulating materials 10a and 10b. At the same time, the above-mentioned insulating sheets S, S1, S2 become the insulating layer 10 and the front and back surface insulating layers 9a, 9b integrally connected to each other, as shown in FIG. The built-in core substrate 1 is obtained. In the core substrate 1, since the insulating materials 10 a and 10 b filled in the plurality of through holes 5 are reduced, dents are less likely to occur on the front surface 11 and the rear surface 12 immediately above and below the cores 1. That is, since the length of the through hole 5 is short and the curing shrinkage of the resin is small, the dent is reduced.
[0027]
FIG. 3 relates to a method (claim 5) for manufacturing the second wiring board 36 according to the present invention. FIG. 3 (A) shows a metal plate 2, 6 made of the copper alloy and having the same thickness as above, having a penetration of 0.3 mm in inner diameter at the same position between the front surfaces 3, 7 and the back surfaces 4, 8 in plan view. The step of forming a plurality of holes 5 by punching is shown. Since the metal plates 2 and 6 are relatively thin, the through-hole 5 penetrating them has a good positional accuracy and has a relatively smooth inner wall.
Next, as shown in FIG. 3B, an insulating sheet S having a thickness of 80 μm is inserted between the back surface 4 and the front surface 7 of the metal plates 2 and 6 in which the through holes 5 are formed. As shown by arrows, pressing is performed by hot pressing along these thickness directions.
[0028]
As a result, as shown in FIG. 3 (C), the insulating sheet S becomes thinner, and at the same time, parts Sa and Sb are pressed into the through holes 5 and 5 of the metal plates 2 and 6 and substantially fill them. As a result, the metal plates 2 and 6 and the insulating sheet S form a closely adhered laminate.
Then, as shown in FIG. 3 (D), the same outer layer insulating sheets S1 and S2 having a thickness of 40 μm as described above are individually formed on the front surface 3 and the back surface 8 of the laminate including the metal plates 2 and 6 and the insulating sheet S. Laminate. Then, as shown by arrows in FIG. 3D, a step of pressing the metal plates 2 and 6, the insulating sheet S, and the outer insulating sheets S1 and S2 while heating them by hot pressing along the thickness direction is performed. . Thereafter, a known curing process of heating and curing the insulating sheets S, S1, and S2 is performed. As a result, a core substrate 1 similar to that shown in FIGS. 1A and 2D can be obtained.
[0029]
The central portions of the through holes 5, 5 of the metal plates 2, 6 in the core substrate 1 obtained by the first or second manufacturing method, the insulating layer 10 located therebetween, and the upper and lower front / back surface insulating layers 9a. , 9b are drilled or laser-processed along the thickness direction. As a result, as shown in FIG. 4A, a through hole 13 having an inner diameter of about 150 μm is formed along the center of the through holes 5 and 5 of the metal plates 2 and 6.
The inner wall of the through hole 13 and the entire surface 11 and the back surface 12 of the core substrate 1 are coated with a plating catalyst such as Pd and subjected to electroless copper plating and electrolytic copper plating. As a result, as shown in FIG. 4B, a substantially cylindrical through-hole conductor 14 having a thickness of about 20 μm is formed along the inner wall of the through-hole 13, and the front surface 11 and the back surface 12 of the core substrate 1 are formed. Copper plating films 11a and 12a are formed on the entire surface.
[0030]
Next, as shown in FIG. 4C, the inside of the through-hole conductor 14 is filled with a non-conductive or conductive filling resin 15 containing an inorganic filler. The upper and lower ends of the filling resin 15 are copper-plated and lid-plated.
Next, an etching resist (not shown) having a predetermined pattern is formed on each of the copper plating films 11a and 12a, and the copper plating films 11a and 12a exposed from gaps between the resists are etched by a known method.
As a result, as shown in FIG. 4C, a front surface wiring layer 16 and a back surface wiring layer 17 are formed on the front surface 11 and the rear surface 12 of the core substrate 1 according to the above-mentioned pattern, and these are formed by through-hole conductors. 14 are connected to each other.
[0031]
Thereafter, the insulating layers 18 and 24, the solder resist layer 30, the wiring layers 22 and 28, and the filled via conductors 20 and 26 that form the build-up layer BU are formed above the surface 11 and the surface wiring layer 16 of the core substrate 1. It is formed by a known build-up process (semi-additive method, full-additive method, subtractive method, formation of an insulating layer by laminating a film-like resin material, photolithography technique, and the like). Further, the solder bumps 32 are formed at appropriate positions on the wiring layer 28.
[0032]
Further, the solder resist layer 19 is formed above (below) the back surface 12 and the back surface wiring layer 17 of the core substrate 1, and is subjected to laser processing to form the opening 23, and the wiring 21 is formed on the bottom surface thereof. It is exposed and its surface is plated.
As a result, the wiring board 36 of the present invention shown in FIG. 1B can be obtained. According to the method of manufacturing the first and second wiring boards 36 of the present invention as described above, the wiring board 36 using the core substrate 1 and having the required board strength and flatness and having stable electrical characteristics is easily used. Can be reliably provided.
Note that a build-up layer BU similar to the above may be formed symmetrically above the back surface 12 and the back surface wiring layer 17 of the core substrate 1.
[0033]
FIG. 5A shows a cross section of a core substrate 1 a which is an application of the core substrate 1.
As shown in FIG. 5A, the core substrate 1a includes a metal plate 2a having a thickness of 0.12 mm, a metal plate 6a having a thickness of 0.08 mm, and a metal plate 6a having a thickness of 0.08 mm. And the same insulating layer 10 as above.
As shown in FIG. 5 (A), the same plurality of through holes 5 penetrate through the same position in plan view between the front surfaces 3, 7 and the back surfaces 4, 8 of the metal plates 2a, 6a. Are filled with the same insulating materials 10a and 10b, and the front surface insulating layer 9a and the back surface insulating layer 9b are formed on the front surface 3 of the metal plate 2a and the back surface 8 of the metal plate 6a. Such a core substrate 1a can also be obtained by the first or second manufacturing method.
[0034]
The same strength and flatness as described above can be obtained by the core substrate 1a. In addition, since the relatively thick metal plate 2a is arranged near the surface 11 of the core substrate 1a, the build-up layer BU is formed only on the surface 11 of the core substrate 1a (only on one surface). Even with a wiring board similar to the wiring board 36, it is possible to eliminate or suppress the warpage such that the build-up layer BU side is depressed.
In the core substrate 1 using the metal plates 2 and 6 having the same thickness, the coefficient of thermal expansion of the metal plate 2 near the front surface 11 of the core substrate 1 is calculated from the coefficient of thermal expansion of the metal plate 6 near the back surface 12. The above-mentioned warpage can be prevented by selecting an object having a larger value.
[0035]
FIG. 5C shows a cross section of a core substrate 40 having a different configuration.
As shown in FIG. 5 (C), the core substrate 40 is made of the copper alloy and has metal plates 41, 44, 47 each having a thickness of 0.08 mm and arranged in parallel with each other, and an insulating member disposed therebetween. And layers 51 and 52. In the metal plates 41, 44, 47, a plurality of through holes 50 coaxially penetrate between the front surfaces 42, 45, 48 and the back surfaces 43, 46, 49 at the same position in plan view. Each of the through holes 50 is filled with the same insulating material as described above, and the surface 42 of the uppermost metal plate 41 and the back surface 49 of the lowermost metal plate 47 are provided with a surface insulating layer (outer insulating layer). 53 and a back surface insulating layer (outer layer insulating layer) 54 are individually formed. The overall thickness between the front surface 55 and the back surface 56 of the core substrate 40 is substantially the same as the thickness of the core substrates 1 and 1a.
The core substrate 40 as described above can also be obtained by the first or second manufacturing method, and the same effects as those of the core substrate 1 can be obtained, and a wiring substrate similar to the wiring substrate 36 can be formed. It is possible.
[0036]
FIG. 5C shows a cross section of a core substrate 40 a which is an application of the core substrate 40. As shown in FIG. 5C, the core substrate 40a includes three metal plates 41a, 44, and 47a made of the copper alloy and arranged in parallel with each other. The thickness of the uppermost metal plate 41a is 0.10 mm, the thickness of the middle metal plate 44 is 0.08 mm, and the thickness of the lowermost metal plate 47a is 0.05 mm. Between the metal plates 41a, 44, 47a, the same insulating layers 51, 52 as described above are located, and between the front surfaces 42, 45, 48 and the back surfaces 43, 46, 49, the same through holes as described above. 50 are formed.
Further, the same surface insulating layer 53 and back surface insulating layer 54 as those described above are individually formed on the front surface 42 of the uppermost metal plate 41a and the back surface 49 of the lowermost layer.
[0037]
The same strength, flatness, and the like can be obtained by the core substrate 40a. Moreover, since the relatively thick metal plate 41a is disposed closer to the front surface 55 of the core substrate 40a and the relatively thin metal plate 47a is disposed closer to the back surface 56, the front surface of the core substrate 40a is reduced. Even with a wiring board similar to the wiring board 36 in which the buildup layer BU is formed only on the 55 (only on one side), it is possible to eliminate or suppress such a warp that the buildup layer BU side is dented. Become.
In the core substrate 40 using the metal plates 41, 44, 47 having the same thickness, the coefficient of thermal expansion of the metal plate 41 near the front surface 55 of the core substrate 40 is determined by the thermal expansion coefficient of the metal plate 47 near the back surface 56. The warpage can also be prevented by setting the coefficient of thermal expansion larger than the coefficient of expansion and selecting the coefficient of thermal expansion of the metal plate 44 in the middle layer between these.
[0038]
The present invention is not limited to the embodiments described above.
In addition to the copper alloy, pure metal, oxygen-free copper, Fe-Ni-based alloys such as Fe-42 wt% Ni and Fe-36 wt% Ni, other steel types, titanium, Alloys, and aluminum and its alloys are also applicable. Further, four or more metal plates can be used in combination for the core substrate 1 and the like.
Further, as the insulating material to be the insulating layer 10 and the like and the front and back surface insulating layers 9a and 9b, it is also possible to apply a prepreg of a composite material in which continuous porous PTFE is impregnated with an epoxy resin.
Further, in addition to the epoxy resin as a main component, a polyimide resin, a BT resin, a PPE resin, or a continuous pore having similar heat resistance and pattern moldability may be used for the insulating layer 18 of the build-up layer BU. A resin-resin composite material obtained by impregnating a resin such as an epoxy resin into a fluorine resin having a three-dimensional network structure such as PTFE can also be used. For forming the insulating layer, a method of applying a liquid resin with a roll coater can be used in addition to a method of thermocompression bonding an insulating resin film. The composition of the glass cloth or glass filler mixed into the insulating layer may be any one of E glass, D glass, Q glass, and S glass, or a combination of two or more of them.
[0039]
The surface wiring layer 16 and the wiring layer 22 of the build-up layer BU may be made of Ag, Ni, Ni—Au, or the like, in addition to Cu (copper). Instead, it may be formed by a method such as applying a conductive resin. Further, instead of the filled via conductor 20 and the like, a conformal via conductor having an inverted conical shape in which the inside of a via hole formed in the insulating layer 18 or the like is not completely filled with a conductor may be used. Alternatively, a staggered configuration in which the via conductors are stacked while shifting their axes may be used, or a configuration in which a wiring layer extending in the plane direction is interposed in the middle.
[Brief description of the drawings]
FIG. 1A is a cross-sectional view showing one embodiment of a core substrate used for a wiring substrate of the present invention, and FIG. 1B is a cross-sectional view showing a wiring substrate of the present invention using such a core substrate.
FIGS. 2A to 2D are schematic views showing each step of a method for manufacturing a first wiring board.
FIGS. 3A to 3D are schematic views showing steps of a method for manufacturing a second wiring board.
FIGS. 4A to 4C are schematic views showing each step following the last step of each of the above-mentioned manufacturing methods.
5A is a cross-sectional view showing an application form of the core substrate of FIG. 1A, FIG. 5B is a cross-sectional view showing a core board of a different form, and FIG. 5C is an application of the core board of FIG. Sectional drawing which shows a form.
6A is a cross-sectional view showing a conventional core board, FIG. 6B is a cross-sectional view showing a metal plate used for the same, and FIG. 6C is a cross-sectional view showing a conventional wiring board using the core board of FIG. FIG.
[Explanation of symbols]
1, 1a, 40, 40a ... core board
2, 2a, 6, 6a, 41, 44, 47 ... metal plate
3,7,42,45,48 ...... Surface of metal plate
4,8,43,46,49 ………… Back side of metal plate
5,50 …………………… Through hole
9a, 53 ... surface insulating layer (outer insulating layer)
9b, 54 …………………… Back insulating layer (outer insulating layer)
10, 51, 52 ... Insulating layer
10a, 10b ……………… Insulating material
11, 55 ............ The surface of the core substrate
12,56 ……………………………… the back side of the core board
16 Surface Wiring Layer
17 …………………… Back wiring layer
18, 24 .................. Insulating layer
22, 28 ...... Wiring layer
36 ............ Wiring board
BU ………………………………… Build-up layer
S …………………………… Insulating sheet
S1, S2 ……………………… Outer insulating sheet
h …………………………… Through-hole

Claims (5)

A plurality of metal plates having a front surface and a back surface and arranged in parallel with each other via an insulating layer,
A through-hole penetrating between the front and back surfaces of the plurality of metal plates,
An insulating material formed in the through hole, and a core substrate including:
A wiring board characterized by the above-mentioned. The wiring board according to claim 1, wherein the through holes are formed at substantially the same positions in the plurality of metal plates as viewed in plan. A surface wiring layer and a back surface wiring layer individually formed on the front and back surfaces of the core substrate via an outer insulating layer, respectively;
A build-up layer comprising a plurality of insulating layers formed above at least one of the front surface wiring layer and the back surface wiring layer and a plurality of wiring layers located therebetween;
The wiring board according to claim 1, further comprising: A step of inserting an insulating sheet between a plurality of parallel metal plates having a front surface and a back surface and closely contacting the same as an insulating layer;
Forming a through-hole along the thickness direction of the laminate comprising the plurality of metal plates and the insulating layer sandwiched therebetween,
A step of laminating an outer insulating sheet on each of the front and back surfaces of the laminate and pressing and adhering them along the thickness direction, and a step of filling the through holes with an insulating material. Including,
A method for manufacturing a wiring board, comprising: A step of forming a through hole at the same position in a plan view in a plurality of metal plates having a front surface and a back surface,
By inserting an insulating sheet between the plurality of parallel metal plates having the through-holes and pressing them along the thickness direction, an insulating layer and an insulating material filled in the through-holes, which are in close contact between the plurality of metal plates. Forming a laminate including:
A step of adhering the outer insulating sheet to the front and back surfaces of the laminate, respectively,
A method of manufacturing a wiring board, comprising: a step of manufacturing a core board having the following.

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