JP3629149B2 - Multilayer wiring board - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention has a plurality of insulating layers including a core substrate, a plurality of conductor layers formed therebetween, and via conductors that conduct these in the thickness direction of the substrate, and an electronic component such as a semiconductor element is provided on the surface. The present invention relates to a multilayer wiring board to be mounted.
[0002]
[Prior art]
In general, as shown in FIG. 4A, the resin multilayer wiring board 50 has an insulating core substrate 52 in the center in the vertical direction (thickness direction) in the figure, and both surfaces of the core substrate 52 are provided. A plurality of conductor layers 60 and 62 and resin layers 64 and 66 are formed substantially symmetrically.
In order to conduct between the conductor layers 60 and 62, a cylindrical through-hole conductor 56 is formed in the through-hole 54 formed in the core substrate 52, and a thermosetting property is formed in the hollow portion 57 thereof. Resin 59 is filled.
[0003]
A circular lid conductor 70 is formed by plating on each horizontal piece 58 extending horizontally from the upper and lower ends of the through-hole conductor 56, and the pair of lid conductors 70 is formed of a thermosetting resin in the hollow portion 57. 59 is sealed.
A bottom portion 76 of a substantially conical via conductor 74 is connected to the center portion of the lid conductor 70, and the via conductor 74 is opposite to the core substrate 52 with the via conductor 70 and the through-hole conductor 56 interposed therebetween. The via conductor 74 is connected. The via conductor 74 is connected to a conductor layer (not shown) on the resin layers 64 and 66 through the horizontal piece 78, for example.
[0004]
[Problems to be Solved by the Invention]
However, as shown in FIG. 4B, when the thermosetting resin 59 filled in the hollow portion 57 is thermoset, the thermosetting resin 59 is cured and contracted accordingly, and the central portion thereof is A recess 71 may be formed. When the lid conductor 70 is formed on the horizontal piece 58 and the thermosetting resin 59 by copper plating, the lid conductor 70 also has a recess 72 formed on its plating surface following the recess 71. As a result, a part of the non-photosensitive resin layer 68 for step correction applied in advance prior to the formation of the resin layer 64 may remain in the recess 72.
As a result, there is a problem that connection failure between the lid conductor 70 and the via conductor 74 occurs, and conduction between the two becomes unstable.
[0005]
In order to prevent such a problem, as shown in FIG. 4C, a through-hole conductor 86 is formed in the through-hole 84 of the core substrate 82, and the connection pad is extended from the upper end to the surface of the core substrate 82. A wiring board 80 on which 88 is formed is used. In this case, the via conductor 87 is formed not on the through hole 84 but on the pad 88. However, when the connection pad 88 is formed, the pad 88 narrows the space of the conductor layer formed on the surface of the core substrate 82, so that there is a problem that a high-density fine pitch cannot be achieved.
The present invention solves the problems in the prior art described above, and can reliably establish conduction between the through-hole conductor and the via conductor or between the via conductors, and also hinder the density of the conductor layer. It is an object of the present invention to provide a multilayer wiring board free from any problem.
[0006]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention has been made paying attention to connecting the through-hole conductor and the via conductor while avoiding the vicinity of the center of the lid conductor having a recess.
That is, the multilayer wiring board of the present invention includes a through-hole conductor formed in a through-hole formed in an insulating core substrate, a filler filled in a hollow portion of the through-hole conductor, and the filler and the through-hole. A lid conductor formed on the upper end of the conductor; a lower resin layer formed on the core substrate so as to be flush with the lid conductor; an upper resin layer formed on the lid conductor and the lower resin layer; And a via conductor formed in the via hole of the upper resin layer so as to be located on the circumference of the through hole or the through hole conductor and connected to the bottom of the lid conductor.
The multilayer wiring board of the present invention includes a through-hole conductor formed in a through-hole formed in an insulating core substrate, a filler filled in a hollow portion of the through-hole conductor, the filler and the through-hole. A circular lid conductor formed on the upper end of the conductor; a lower resin layer formed on the core substrate so as to be flush with the lid conductor; and an upper resin layer formed on the lid conductor and the lower resin layer; And a via conductor formed in the via hole of the upper resin layer so as to avoid the central portion of the lid conductor and to connect the bottom portion to the flat portion of the lid conductor.
[0007]
According to these wiring board, even if the recess is formed near the center of the lid conductor, the connection between the lid conductor and via conductors reliably performed, it can take stably conduction of a plurality of conductor layers In addition, the density of the conductor layer on the core substrate surface is not hindered.
In addition to the composite material of BT resin-glass fiber described later, a known insulating substrate or a metal plate whose surface is coated with an insulating material can be used as the core substrate. Further, the lower resin layer is filled between the lid conductor and the conductor layer, and a non-photosensitive resin that eliminates a step between the lower resin layer and the core substrate is used. Further, a photosensitive resin is used for forming a via hole in the upper resin layer.
[0008]
On the other hand, another multilayer wiring board according to the present invention includes a first via conductor formed in a via hole formed in the first resin layer, a filler filled in a recess in the first via conductor, A lid conductor formed at the upper end of the filler and the first via conductor, a lower layer formed on the first resin layer so as to be flush with the lid conductor, and an upper layer formed thereon In the via hole in the upper layer of the second resin layer so as to be located on the circumference of the upper end of the first via conductor and to be connected to the bottom of the lid conductor. And a second via conductor formed on the substrate.
According to this wiring board, even if the recess is formed in the center portion of the lid conductor, the upper and lower via conductors can be reliably connected via the lid conductor, and the conduction between the plurality of conductor layers can be stably performed. It can be taken, and there is no hindrance to increasing the density of each conductor layer.
[0009]
Furthermore, a multilayer wiring board in which the filler contains one or both of a conductive substance and a plating catalyst component is also proposed. According to this, by using a conductive material such as copper paste, a catalyst core for plating, or a filler containing both of them, a lid conductor formed by plating or the like is easily and thinly formed on the upper end thereof. obtain. The plating catalyst component includes a catalyst core for plating such as Pd that promotes adhesion and growth of copper plating. When a non-conductive substance such as a paste containing ceramic powder is used as a filler, the shrinkage is reduced, the recess formed in the lid conductor is shallow and small, and the via conductor is to be connected to the via conductor. It becomes possible to expand the range in.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
In the following, preferred embodiments of the present invention will be described with reference to the drawings.
FIG. 1A shows a cross section of the main part of the multilayer wiring board 1 of the present invention. The wiring substrate 1 includes a core substrate 2 at the center in the vertical (thickness) direction, conductor layers 15 and 15 'formed on both sides thereof, lower resin layers 16 and 16', and upper resin layers 18 and 18 '. And have.
The core substrate 2 is made of a composite material of BT (bismaleimide trizian) resin and glass fiber cloth, and has a large number of through holes 4 formed therein. A substantially cylindrical through-hole conductor 6 is formed in the through-hole 4 by copper plating, and a thermosetting resin (filler) 9 is filled in the hollow portion 7 by mask printing. Further, horizontal pieces 8 and 8 ′ extending in a ring shape on the surface of the core substrate 2 are integrally formed at the upper and lower ends of the through-hole conductor 6.
[0011]
Further, circular lid conductors 10 and 10 ′ are formed on the horizontal pieces 8 and 8 ′ of the through-hole conductor 6 and the thermosetting resin 9, and are connected to the through-hole conductor 6. In the gaps between the horizontal pieces 8, 8 'and the cover conductors 10, 10' and the conductor layer 15, there are lower resin layers 16, 16 'made of non-photosensitive resin so as to form the same plane with the same thickness as these. It is arranged. Further, upper resin layers 18 and 18 'made of a photosensitive resin are formed so as to cover substantially the entire surface above them. In the resin layers 18 and 18 ′, substantially conical via conductors 20 and 20 ′ are respectively formed on the through holes 4 at positions on the substantially circumference (cylindrical body) of the through hole conductor 6. Connected to conductors 10 and 10 '.
[0012]
As shown in an enlarged view in FIG. 1 (B), the thermosetting resin 9 filled in the hollow portion 7 of the through-hole conductor 6 in an uncured (varnish) state has upper and lower ends when it is thermally cured. The dent 11 is formed at the upper end of the thermosetting resin 9 by slightly shrinking. A recess 12 is formed in the vicinity of the center of the lid conductor 10 on the horizontal piece 8 and the thermosetting resin 9, following the recess 11. However, as shown in the figure, the via conductor 20 has a bottom 22 on the flat portion 14 that is located approximately on the circumference of the through-hole conductor 6 away from the center of the through-hole 4 in which the recess 12 is formed. Formed. As a result, the through-hole conductor 6 and the via conductor 20 are connected via the flat portion 14 of the lid conductor 10 and are electrically connected to each other.
[0013]
Therefore, according to this multilayer wiring board 1, even when a part of the non-photosensitive lower resin layer 16 remains in the recess 12 at the center of the lid conductor 10, the above-described conduction is ensured, and the core board 2 Conduction between the conductor layer 15 on the surface and an upper conductor layer (not shown) is also ensured. Furthermore, electrical connection between the via conductor 20 and an electronic component mounted on the surface of a solder resist layer (not shown) formed on the upper resin layer 18 can be ensured. In addition, the density of the conductor layer 15 (15 ') is not hindered, and the multilayer wiring board 1 can be made dense and highly reliable.
[0014]
FIG. 2 relates to a method of manufacturing the multilayer wiring board 1, and FIG. 2A shows that a through-hole conductor 6 is formed in the through-hole 4 of the core substrate 2, and a thermosetting resin 9 is filled in the hollow portion 7. In addition, a state in which the lid conductor 10 is connected to the horizontal piece 8 of the conductor 6 is shown.
The core substrate 2 is coated with copper foil on both surfaces in advance, and a through-hole is formed by drilling a hole penetrating the copper foil, and electroless copper plating and electrolytic copper plating are applied to the inside thereof. A hole conductor 6 is formed. Next, after covering the entire surface of the copper foil of the core substrate 2 with a photosensitive resin (not shown), exposure and development according to a predetermined pattern are performed. As a result, the horizontal piece 8 (8 ') and the conductor layer 15 (15') are formed on both surfaces of the core substrate.
[0015]
After filling the hollow portion 7 of the through-hole conductor 6 with a thermosetting resin material and thermosetting to form the thermosetting resin 9, the horizontal pieces 8 (8 ') and the upper and lower sides of the thermosetting resin 9 are Further copper plating is performed on the end face and the conductor layer 15 (15 '). Then, a circular lid conductor 10 (10 ') is formed on the horizontal piece 8 (8') and the thermosetting resin 9, and the conductor layer 15 (15 ') increases the thickness of this plating. In addition, since the dent 11 is formed in the center part of the thermosetting resin 9 at the time of the said thermosetting, the dent 12 is formed in the center part of the lid | cover conductor 10 according to this in illustration.
[0016]
Next, as shown in FIG. 2B, for example, an epoxy non-photosensitive resin 16 a is applied to the surface of the core substrate 2 so as to cover the conductor layer 15 and the lid conductor 10.
Further, a cylindrical polishing roll having elasticity (not shown) is moved in the horizontal direction in the drawing along the surface of the resin 16a. As a result, as shown in FIG. 2C, the excessive resin 16a on the upper side is removed, and the lower resin layer 16 is formed so as to have the same plane as the lid conductor 10 and the conductor layer 15 in the same plane. The At this time, a part of the resin 16a remains in the recess 12 at the center of the lid conductor 10.
[0017]
Next, for example, an epoxy-based and photosensitive upper resin layer 18 is formed on the lower resin layer 16, and exposure and development according to a predetermined pattern are performed. As a result, as shown in FIG. 2D, a substantially conical via hole 19 is formed in the upper resin layer 18 on the substantially circumference of the through-hole conductor 6.
Next, after covering the entire surface of the upper resin layer 18 including the inside of the via hole 19 with a copper film by electroless copper plating and electrolytic copper plating, a photosensitive resin film (not shown) is pasted, and exposure according to a predetermined pattern is performed. When development and etching are performed, a via conductor 20 is formed in the via hole 19 as shown in FIG. The via conductor 20 is connected to the horizontal piece 8 of the through-hole conductor 6 through the bottom conductor 22 connected to the flat portion 14 of the lid conductor 10 away from the recess 12.
[0018]
The horizontal piece 24 of the via conductor 20 can also be used as a land for connecting electronic parts by applying nickel and gold plating. In this embodiment, only one layer of the via conductor 20 is formed, but it goes without saying that it can be formed in each of two or more resin layers. Further, when the filler 9 is formed of a conductive material such as copper paste or includes a catalyst core for plating such as palladium, the lid conductor 10 can be easily formed by the copper plating. It is also possible to form the lid conductor 10 with a metal-deposited thin film having a thickness of 10 μm or less by sputtering (vacuum deposition).
[0019]
FIG. 3 is a cross-sectional view showing a main part of a multilayer wiring board 40 of a different form according to the present invention. In addition, the same code | symbol shall be used for the part and element which are common in the said form.
The wiring board 40 includes a plurality of through holes 4, a through hole conductor 6 and a thermosetting resin (filler) 9 in the same core substrate 2 as described above, and lid conductors 10 and 10 'on upper and lower ends thereof. And conductor layers 15 and 15 ′ are formed on both surfaces of the core substrate 2. First resin layers 17 and 17 'including the lower resin layers 16 and 16' and the upper resin layers 18 and 18 'are formed on the lid conductors 10 and 10' and the conductor layers 15 and 15 ', respectively. In addition, first via conductors 20, 20 'are formed in the via holes 19, 19' of the upper resin layers 18, 18 '.
[0020]
The recesses 26 and 26 ′ of the via conductors 20 and 20 ′ are also filled with the same fillers 28 and 28 ′, and on the horizontal pieces 24 and 24 ′ of the via conductors 20 and 20 ′. Circular lid conductors 30 and 30 'covering the fillers 28 and 28' are formed. On the upper resin layers 18 and 18 ', horizontal pieces 24 and 24' of the via conductors 20 and 20 ', cover conductors 30 and 30', and conductor layers 33 and 33 'are formed. Further, lower layers 35 and 35 'of the second resin layers 34 and 34' are disposed between the lid conductors 30 and 30 'and the conductor layers 33 and 33' so as to form the same plane as these. The
Then, second via conductors 38 and 38 'are formed on the flat portions of the periphery of the lid conductors 30 and 30' and on the circumference of the upper ends of the via conductors 20 and 20 ', and the conductor layer 33 is formed around the second via conductors 38 and 38'. , 33 ', etc., upper layers 36, 36' of the second resin layer 34 are formed.
[0021]
The fillers 28 and 28 ′ filled in the recesses 26 and 26 ′ of the via conductors 20 and 20 ′ may contract, and the center portions of the lid conductors 30 and 30 ′ may be recessed as described above. Even in that case, the via conductors 38 and 38 'connected to the via conductors 38 and 38' are formed on the flat portions of the peripheral edges of the lid conductors 30 and 30 'where the centers of the bottom portions 39 and 39' are out of the recesses. The conduction between the via conductors 20 and 38 and the via conductors 20 'and 38' can be ensured. Moreover, since the via conductors 20, 20 ′ are electrically connected to each other through the lid conductors 10, 10 ′ and the through-hole conductor 6, the wiring substrate 40 has the conductor layers 15 formed on both sides with the core substrate 2 interposed therebetween. , 15 ', 33, 33' is formed as a reliable three-dimensional circuit.
Further, another conductor layer 42, 42 'is formed on the second resin layer 34, 34', a solder bump 44 protruding on the surface of the solder resist layer 46 formed thereon, or a solder resist It is also clear that the exposed terminals 48 can be formed between the layers 46 'so that they can be electrically connected to the mounted electronic components and the like.
[0022]
The present invention is not limited to the embodiments described above.
For example, a BT resin-glass fiber cloth composite material not coated with copper foil is used for the core substrate, a through hole is formed in the core substrate and a through hole conductor is formed, and then electroless copper plating or the like is performed. And a conductor layer may be formed on the surface. In addition to a composite material such as a glass-epoxy material, a glass-PPE material, or a paper-epoxy material, a known insulating substrate or a metal plate whose surface is coated with an insulating material is used for the core substrate. Is also possible.
[0023]
When the resin layer of the insulating material has a required strength, it is obvious that a multilayer wiring board in which the core board is omitted is also included in the subject of the present invention.
Furthermore, the conductor layer and the resin layer formed on both surfaces of the core substrate need not be formed symmetrically on both surfaces of the core substrate, and may be a multilayer wiring substrate in which the conductor layer and the resin layer are formed asymmetrically on both surfaces. .
Further, it is also possible to use a metal such as Ni other than copper or an alloy thereof for the wiring patterns of the through-hole conductor, via conductor, and conductor layer.
[0024]
【The invention's effect】
According to the multilayer wiring board of the present invention described above (claims 1 and 2), conduction between the through-hole conductor formed in the core substrate and the via conductor formed in the resin layer can be easily and reliably performed, and the core substrate A high-density wiring pattern can be formed without hindering the fine pitch of the upper conductor layer.
Moreover, according to the multilayer wiring board of claim 3, via conductors arranged along the thickness direction can be reliably conducted to each other, and it is possible to contribute to higher density of each conductor layer.
Furthermore, according to the multilayer wiring board of the fourth aspect, it is possible to facilitate the plating of the lid conductor and reduce the thickness thereof.
[Brief description of the drawings]
1A is an end view showing a main part of a multilayer wiring board according to one embodiment of the present invention, and FIG. 1B is an enlarged view of a one-dot chain line portion B in FIG.
FIGS. 2A to 2E are end views showing respective manufacturing steps of the multilayer wiring board of FIG.
FIG. 3 is an end view showing a main part of a multilayer wiring board of a different form according to the present invention.
4A is an end view showing a main part of a conventional multilayer wiring board, FIG. 4B is an enlarged view of a one-dot chain line portion B in FIG. 4A, and FIG. Schematic.
[Explanation of symbols]
1, 40... Multilayer wiring board 2... Core substrate 4... Through hole 6... Through hole conductor 7. (Filler)
DESCRIPTION OF SYMBOLS 10, 30 ... Cover conductor 16 ............ Lower resin layer 17 ............ 1st resin layer 18 ............ Upper resin layer 19 ............ Via hole 20, 38 ... Via conductor 22, 39 ... Bottom part 26 ………… Recess 34 ………… Second resin layer 35 ………… Lower layer 36 ………… Upper layer

Claims (4)

A through-hole conductor formed in a through-hole drilled in an insulating core substrate;
A filler filled in the hollow portion of the through-hole conductor;
A lid conductor formed at the upper end of the filler and through-hole conductor;
A lower resin layer formed on the core substrate so as to be flush with the lid conductor;
An upper resin layer formed on the lid conductor and the lower resin layer;
A via conductor formed in the via hole of the upper resin layer so as to be positioned on the circumference of the through hole or the through hole conductor and connected to the bottom of the lid conductor.
A multilayer wiring board characterized by that. A through-hole conductor formed in a through-hole drilled in an insulating core substrate;
A filler filled in the hollow portion of the through-hole conductor;
A circular lid conductor formed at the upper end of the filler and through-hole conductor;
A lower resin layer formed on the core substrate so as to be flush with the lid conductor;
An upper resin layer formed on the lid conductor and the lower resin layer;
Including a via conductor formed in the via hole of the upper resin layer so as to avoid the center portion of the lid conductor and to connect the bottom to the flat portion of the lid conductor.
A multilayer wiring board characterized by that. A first via conductor formed in a via hole formed in the first resin layer;
A filler filled in the recess in the first via conductor;
A lid conductor formed on an upper end of the filler and the first via conductor;
A second resin layer comprising a lower layer formed on the first resin layer so as to be flush with the lid conductor, and an upper layer formed thereon;
A second via conductor formed in a via hole in the upper layer of the second resin layer so as to be located on the circumference of the upper end of the first via conductor and to have a bottom connected to the lid conductor. A multilayer wiring board characterized by that. The filler includes one or both of a conductive material and a plating catalyst component;
The multilayer wiring board according to any one of claims 1 to 3, characterized in that.

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