JP2006253372A - Multi-layer printed wiring board and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wiring board capable of solving the problem that a multi-layer core printed board has less flexibility of circuit designs because of wiring and connection using through-holes, and also a built-up board has high flexibility of designs, but it is unlikely to be used as a high frequency board because of its variation of a built-up layer. <P>SOLUTION: The multi-layer core board 12 in which a first core insulating layer 4 is put between a second core insulating layer 10 and a third core insulating layer 11, includes internal layer patterns 3, 5 on the inside thereof, and includes an upper layer pattern 1 and a lower layer pattern 6 on the outside thereof. Metal plating 9 is applied to inner surfaces of through-holes 8 formed in the multi-layer core board 12 to electrically connect the internal layer patterns 3, 5, and resin 13 is embedded in the through-holes 8. A receiving pattern 17 for the through-hole 8 is eliminated together with a part of the metal plating 9 in the through-holes 8 in etching of the lower layer pattern 6 to prevent the electrical connection between the lower layer pattern 6 and the internal layer patterns 3, 5, and to permit the electrical connection between the upper layer pattern 1 and the internal layer patterns 3, 5. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a multilayer printed wiring board and a method for manufacturing the same.

  As shown in FIG. 6, the conventional multilayer printed wiring board has first and second inner layer patterns as a desired pattern circuit by etching a metal film conductor layer bonded to both surfaces of an insulating layer substrate. 3 and 5, the first core insulating layer 4, the second core insulating layer 10 in a semi-cured state in which the conductor layer of the metal film is bonded on one side, and the first core insulating layer 4. 3, and the first core insulating layer 4 is the second core insulating layer so that the conductor layers of the second core insulating layer 10 and the third core insulating layer 11 are on the outer surface. A multilayer core substrate is formed which is sandwiched from above and below by the layer 10 and the third core insulating layer 11 and laminated by hot pressing or the like.

  A through hole 8 is formed in the multilayer core substrate, and a metal plating 9 is applied to the inner surface of the through hole 8, and then an insulating resin 13 is filled into the through hole 8. Then, the core multilayer printed wiring board is configured by forming the upper layer pattern 1 and the lower layer pattern 6 to be the wiring pattern and the through hole receiving pattern by etching or the like on the conductive layers of the metal films on both surfaces of the core multilayer board. .

  Here, the through hole receiving pattern is a pattern required when metal plating is performed on the inner surface of the through hole, and is a pattern that is at least 50 μm larger than the diameter of the through hole. This receiving pattern is often included together with the wiring pattern of each layer. However, in this core multilayer printed wiring board, there are many restrictions on the wiring pattern design, and the diameter of the through hole cannot be reduced. In addition, the distance between the through holes is required, and the degree of design freedom is very small.

Therefore, in recent years, as shown in FIG. 7, a through hole 8 is provided in the substrate of the first core insulating layer 4, a metal plating 9 is applied to the inner surface of the through hole 8, and an insulating resin 13 is filled. Then, the built-up insulating layer 2 is formed on the first core insulating layer 4 on which the first and second inner layer patterns 3 and 5 are formed by etching or the like of the surface conductor layer. Via holes 7 are made in the built-up insulating layer 2 to the conductor layer of the first core insulating layer 4 by laser processing or the like, and metal plating 9 is applied to the via holes 7, so that the first, Electrical connection is made with the second inner layer patterns 3 and 5. A built-up multilayer printed wiring board laminated by repeating this process is widely used at present.
Japanese Patent Laid-Open No. 10-341077 JP 2001-257470 A

  In a multilayer printed wiring board, in the case of a core multilayer printed wiring board, since electrical connection between each layer is performed using a through hole, electrical connection between inner layers cannot be performed. Therefore, a built-up multilayer printed wiring board is used when electrical connection is necessary due to a layer error. Since the via hole in the built-up insulating layer can be drilled to the underlying conductor pattern using a laser or the like for processing the via, the via hole can be easily formed. Also, the hole diameter can be made smaller than the through hole, and the via interval can be made narrower than the through hole. Therefore, the electrical connection place between the layers can be freely changed, and the degree of freedom in the board design is increased.

  However, since the built-up insulating layer has a low viscosity, it is difficult to increase the layer thickness. Further, the variation in the layer thickness is large with respect to the core layer, and when used as a high-frequency multilayer printed wiring board, the characteristic impedance of the microstrip line becomes unstable.

  In the manufacturing process, after forming the double-sided pattern on the core substrate, via holes are created, plated, filled with an insulating resin, a built-up insulating layer is laminated, and core multilayer printed wiring is used to create via holes by laser processing etc. The manufacturing time is increased because the process time is longer than the process of creating the substrate and the number of steps is increased.

  It is an object of the present invention to provide a multilayer printed wiring board and a method for manufacturing the same, which solve the above-described problems of the prior art while using the core multilayer printed wiring board process.

  In order to achieve the above object, the multilayer printed wiring board according to the present invention comprises a multilayer board having two or more layers, a through hole penetrating the multilayer board and metal-plated inside, and the inside of the through hole. In the multilayer printed wiring board that electrically connects the upper and lower wiring patterns in the multilayer board by the metal plating, the through hole is formed on the upper surface and the lower surface of the multilayer board in the through hole. It is characterized in that at least either one has no receiving pattern.

  Further, the present invention is characterized in that a part of the metal plating inside the through hole without the receiving pattern is etched.

  According to the present invention, at least one built-up insulating layer is laminated on the multilayer substrate.

  Further, the present invention is characterized in that the through hole having no receiving pattern is covered with a resist film.

  Further, the present invention is characterized in that an inductor component is provided by drawing a wiring pattern using two layers of the through hole without the receiving pattern and the multilayer substrate.

  The present invention is characterized in that interference between the wiring pattern and the ground of the through hole is reduced by using the through hole without the receiving pattern.

  The present invention also includes a multilayer substrate having two or more layers, a through-hole formed by metal plating around the inside of the multilayer substrate, and a resin filled in the through-hole. In the method of manufacturing a multilayer printed wiring board in which upper and lower wiring patterns in the multilayer board are electrically connected, the conductive layers formed on the upper and lower surfaces of the multilayer board are etched to form a wiring pattern, and at the same time, receive the through-hole. The pattern is etched.

  Further, the present invention is characterized in that a part of the metal plating of the through hole is etched simultaneously with the etching of the receiving pattern of the through hole.

  According to the present invention configured as above, the uppermost layer and the inner layer, the inner layer and the lowermost layer, and the inner layer can be electrically connected to each other even if through holes are used, and there is no need to add a new process for a short time. It is possible to create between. Furthermore, since the laminated layer is formed using a semi-cured insulating layer substrate without using a built-up layer substrate, the insulating layer has a stable thickness, and can be used as a multilayer printed wiring board for high frequencies.

  Further, since the metal plating on the inner surface of the through hole is removed during the etching, the interference of the electromagnetic field between the through hole and the surrounding wiring pattern hardly occurs. Therefore, since the wiring pattern can be brought to the periphery of the through hole, it is not necessary to increase the substrate area for wiring.

  According to the present invention, it is possible to increase the degree of design freedom as compared with the prior art because the electrical connection between the layers can be made through the through-hole without using a built-up board, and multilayer printed wiring without adding a new process. A substrate can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is an explanatory diagram showing the structure of the multilayer wiring printed board according to the first embodiment of the present invention. The first core insulating layer 4 is sandwiched between the first inner layer pattern 3 and the second inner layer pattern 5 which are upper and lower conductor layers, and the first core insulating layer 4 is further connected to the second core insulating layer 4. The multilayer core substrate 12 is configured by being sandwiched between the layer 10 and the third core insulating layer 11. On the upper and lower surfaces of the multi-layer core substrate 12, an upper layer pattern 1 and a lower layer pattern 6 which are wiring patterns made of conductor layers are formed.

  A through-hole 8 is formed in the multilayer core substrate 12, and a metal plating 9 is applied to an inner surface of the through-hole 8, and the first and second inner layer patterns 3, 5 are provided via the metal plating 9. Alternatively, the first and second inner layer patterns 3 and 5 are electrically connected to at least one of the upper layer pattern 1 or the lower layer pattern 6. Here, there is no restriction | limiting in particular about the formation method of the through-hole 8, What is necessary is just to form by mechanical grinding. The resin 13 is embedded in the through-hole 8, and the material of the resin 13 is not particularly limited and is not particularly limited as long as the purpose is achieved with either an insulating resin or a conductive resin.

  FIG. 2 is an explanatory view showing the structure before and after forming the upper layer pattern 1 and the lower layer pattern 6 on the multilayer core substrate 12, and 17 shows a receiving pattern of the through holes 8. As described in the background art section, the receiving pattern 17 is a pattern required when metal plating is performed on the inner surface of the through hole 8.

  First, from both sides of the first core insulating layer 4 in which the first inner layer pattern 3 and the second inner layer pattern 5 are formed, the second core insulating layer 10 in which the upper layer pattern 1 is not formed, and the lower layer pattern 6 A multilayer core substrate 12 is formed by sandwiching the third core insulating layer 11 on which no is formed.

  Next, after forming a conductive layer to be the upper layer pattern 1 or the lower layer pattern 6 on both surfaces of the multilayer core substrate 12, the through holes 8 are formed in the multilayer core substrate 12. Further, the inner surface of the through hole 8 is subjected to metal plating, and then the through hole 8 is filled with the resin 13.

  Next, the upper layer pattern 1 or the lower layer pattern 6 is formed by performing pattern etching on the conductive layers on both surfaces of the multilayer core substrate 12.

  Here, when the conductive layer in the region corresponding to the receiving pattern 17 of the through-hole 8 is formed on the second core insulating layer 11 as shown in FIG. 2A, the pattern of the lower layer pattern 6 It is removed by being etched at the same time as etching. Further, the metal plating 9 inside the through-hole 8 is also etched at the same time to form a removal portion 14 without the metal plating 9, and the lower layer pattern 6 and the second inner layer pattern 5 are not electrically connected.

  By doing so, the upper layer pattern 1 and the first and second inner layer patterns 3 and 5 can be electrically connected. For example, when a conductor pattern having a thickness of about 40 μm is etched, the metal plating on the side surface of the through hole having a diameter of 150 μm is etched to a depth of about 20 μm. Therefore, the thickness of the second and third core insulating layers 10 and 11 is desirably 50 μm or more.

  In addition, the part which is not electrically connected is a wiring layer which forms the pattern 1 of an upper layer and the wiring layer which forms the 1st, 2nd inner layer patterns 3 and 5 inside as shown in FIG.2 (b). There may be. Further, as shown in FIG. 2 (c), there is no connection between the upper and lower layer patterns 1 and 6 and the first and second inner layer patterns 3 and 5, and the first and second inner layer patterns 3 and 5 are formed. It may be a multilayer substrate connected between conductive layers.

  Further, as shown in FIG. 3, the core insulating layer may be two layers. 3A shows the case of two layers of core insulating layers 4 and 11, and FIG. 3B shows the case of two layers of core insulating layers 10 and 4, respectively.

(Second Embodiment)
FIG. 4 is an explanatory view showing the structure of the multilayer printed wiring board according to the second embodiment of the present invention. In the second embodiment, a built-up insulating layer 2 is further laminated on the multilayer printed wiring board of the first embodiment shown in FIGS. That is, the built-up insulating layer 2 is laminated on the second core insulating layer 10 and the third core insulating layer 11 so as to sandwich the upper layer pattern 1 and the lower layer pattern 6. Via holes 7 are formed in the built-up insulating layer 2 to the conductor layer of the second core insulating layer 10 and the conductor layer of the third core insulating layer 11 by laser processing or the like, and metal plating is applied to the via hole 7 to form an upper layer. The pattern 1 and the lower layer pattern 6 or the first and second inner layer patterns 3 and 5 of the first core insulating layer 4 are electrically connected.

(Third embodiment)
FIG. 5 is an explanatory view showing the structure of a multilayer printed wiring board according to the third embodiment of the present invention. In the multilayer printed wiring board according to the first embodiment shown in FIG. 2, if there is a through hole 8 without a receiving pattern 17 on the back surface, solder may turn around and cause a short circuit during mounting. Therefore, in the third embodiment, the portion of the through hole 8 is covered with the solder resist 16.

  By comprising in this way, since a solder does not approach into the through-hole 8, it can prevent a short circuit.

  The multilayer printed wiring board of the present invention is useful as a technique for reducing the cost of a multilayer printed board that can be integrated without increasing the board area while using a through-hole in the core multilayer board.

The perspective view which shows the structure of the multilayer printed wiring board of the 1st Embodiment of this invention Sectional drawing which shows the structure in the time before and behind forming the upper layer pattern 1 and the lower layer pattern 6 in the multilayer core board | substrate 12 in 1st Embodiment Sectional drawing which shows the structure which applied the 1st Embodiment of this invention to the printed wiring board of two layers FIG. 3 is an oblique sectional view showing the structure of the multilayer printed wiring board according to the second embodiment of the present invention Sectional drawing which shows the structure of the multilayer printed wiring board of the 3rd Embodiment of this invention Sectional view of a conventional core multilayer wiring board Cross-sectional view of a conventional built-up multilayer wiring board

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Upper layer pattern 2 Built-up insulating layer 3 1st inner layer pattern 4 1st core insulating layer 5 2nd inner layer pattern 6 Lower layer pattern 7 Via hole 8 Through-hole 9 Metal plating 10 2nd core insulating layer 11 3rd core Insulating layer 12 Multi-layer core substrate 13 Resin 14 Removal portion 15 Built-up multilayer substrate 16 Solder resist

Claims (8)

  A multilayer substrate having two or more layers; a through-hole formed by metal plating the inner periphery of the multilayer substrate; and a resin filled in the through-hole. In the multilayer printed wiring board for electrically connecting the wiring patterns of the multilayer printed wiring board, the through hole is configured to have no receiving pattern on at least one of the upper surface and the lower surface of the multilayer substrate in the through hole. substrate.   2. The multilayer printed wiring board according to claim 1, wherein a part of the metal plating inside the through hole having no receiving pattern is etched.   The multilayer printed wiring board according to claim 1, wherein at least one built-up insulating layer is laminated on the multilayer board.   3. The multilayer printed wiring board according to claim 1, wherein the through-hole having no receiving pattern is covered with a resist film.   4. The multilayer printed wiring board according to claim 1, 2, or 3, wherein an inductor component is provided by drawing a wiring pattern using two layers of the through hole without the receiving pattern and the multilayer board. .   4. The multilayer printed wiring board according to claim 1, wherein interference between the wiring pattern and the ground of the through hole is reduced by using the through hole without the receiving pattern. A multilayer substrate having two or more layers; a through-hole formed by metal plating the inner periphery of the multilayer substrate; and a resin filled in the through-hole. In the manufacturing method of the multilayer printed wiring board for electrically connecting the wiring patterns of
A method of manufacturing a multilayer printed wiring board, comprising: etching a conductive layer formed on the upper and lower surfaces of the multilayer board to form a wiring pattern, and simultaneously etching the receiving pattern of the through hole.   8. The method of manufacturing a multilayer printed wiring board according to claim 7, wherein a part of the metal plating of the through hole is etched simultaneously with the etching of the receiving pattern of the through hole.

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