JP6326385B2 - Multilayer wiring board - Google Patents

Description

  The present invention relates to a multilayer wiring board formed by laminating a core material and a prepreg.

  Conventionally, a multilayer wiring board has a hardened insulating material as a core material, a semi-cured insulating material as a prepreg, and a surface layer and an inner layer formed by stacking the core material and the prepreg as a printed wiring surface. Used (see, for example, Patent Document 1).

  FIG. 3 shows an example of a conventional multilayer wiring board. In the figure, 1-1 and 1-2 are core materials, 2-1 is a prepreg, and the prepreg 2-1 has a laminated structure sandwiched between the core material 1-1 and the core material 1-2. The upper surface of the core material 1-1 is the surface layer (first layer) L1, the layer between the core material 1-1 and the prepreg 2-1 is the inner layer (second layer) L2, the prepreg 2-1 and the core material 1-. 2 is an inner layer (third layer) L3, and the lower surface of the core material 1-2 is a surface layer (fourth layer) L4.

  In this multilayer wiring board (four-layer wiring board) 100, the surface layers L1 and L4 and the inner layers L2 and L3 are used as printed wiring surfaces, and various wiring patterns including component pads are formed on the printed wiring surface.

  FIG. 4A illustrates a wiring pattern formed on the surface layer L1, and FIG. 4B illustrates a wiring pattern formed on the inner layer L2. In FIG. 4, the blacked out portion is a wiring pattern including component pads formed of copper foil.

  In such a multilayer wiring board, in order to ensure insulation between circuits (between patterns and parts), a distance greater than a specified value must be separated. This distance is usually referred to as a spatial distance, but is applied not only to the surface layer but also to the inner layer. When the solid insulator is sandwiched between these distances, it is called “separation distance through the solid insulator” (hereinafter referred to as solid separation distance), and the distance that should be separated from the normal space distance is relaxed. Even if it is sandwiched between insulators, at least the solid separation distance must be separated.

  In the case of a multilayer wiring board, since the distance between the surface layer and the inner layer or between the inner layer and the inner layer is sandwiched between solid insulators, a solid separation distance is applied. The definition and numerical value of the solid separation distance are defined by international standards for intrinsically safe explosions, JIS (see Non-Patent Document 1), and the like. As an example, in a circuit area where the voltage (peak voltage value) can be 10 V or 30 V, the solid separation distance between the target circuits must be 0.5 mm or more.

  On the other hand, in the design of a printed wiring board, if a relatively large circuit is to be mounted while the size of the board is limited, it is usually not an inexpensive one side board (one layer) or both side boards (two layers). In many cases, it is designed as a multilayer substrate (multilayer wiring substrate) of layers, 6 layers, 8 layers or the like. Regarding the layer structure of this multilayer wiring board, it is usually the board manufacturer that manufactures the board, and each board manufacturer has its own standard specification layer structure. In consideration of cost, it is usually manufactured using the standard specifications of each board manufacturer. To do. In addition, the standard specification configuration differs slightly depending on each board manufacturer.

  A configuration example of the standard specification of the multilayer wiring board is shown below. In the case of a four-layer wiring board, a configuration as indicated by reference numeral 101 in FIG. 5 (1-1: core material, 2-1, 2-2: prepreg, L1, L4: surface layer, L2, L3: inner layer) and It is common to do. This is because the substrate material and manufacturing process are optimized. In the case of a six-layer wiring board, a configuration as indicated by reference numeral 102 in FIG. 6 (1-1, 1-2: core material, 2-1 to 2-3: prepreg, L1, L6: surface layer, L2 to L5 In the case of an 8-layer wiring board, a configuration as indicated by reference numeral 103 in FIG. 7 (1-1 to 1-3: core material, 2-1 to 2-4: prepreg, L1, L8: Surface layer, L2 to L7: inner layer), but this configuration often differs depending on the substrate manufacturer. This is because the materials and processes stocked as standard vary by manufacturer. Also, the thickness of each layer varies somewhat depending on the substrate manufacturer.

  There are two types of insulating materials used for multilayer wiring boards. One is a glass epoxy resin already cured, and the other is a glass epoxy resin semi-cured. In the multilayer wiring board, a cured glass epoxy resin (insulating material) is used as a core material, and a semi-cured glass epoxy resin (insulating material) is used as a prepreg. The core material is procured by the substrate manufacturer from the core material manufacturer and used for each thickness. On the other hand, the prepreg is in the form of a cloth, and a plurality of these prepregs are heated and pressurized to adhere to other copper foils or core materials to become a cured glass epoxy resin. Since the prepreg is liquefied once during the heat and pressure treatment, it is difficult to manage and control the thickness, and it is extremely rare for the substrate manufacturer to guarantee the thickness of the prepreg after curing.

  When securing the distance in the multilayer wiring board, if the pattern is on the surface layer, the board may be designed so that the specified distance is separated by simply drawing the pattern at the time of designing the board. However, such substrate design cannot cope with the pattern between the surface layer and the inner layer and between the pattern between the inner layer and the inner layer, and the thickness between the substrate layers must be ensured by reviewing the substrate structure.

For this reason, conventionally, as shown in FIG. 3, without using a standard multilayer wiring board, the core materials 1-1 and 1-2 capable of managing the thickness are arranged on both sides, and the prepreg 2- 1 is arranged to guarantee the separation distance defined in the intrinsically safe explosion-proof (hereinafter also referred to as intrinsically safe explosion- proof standard) .

JP2013-254952A

JIS C60079-11 Electrical machinery used in explosive atmospheres-Part 11: Intrinsically safe explosion-proof structure "i"

  However, in this method, the thickness of the core material to be used is often special, and there are disadvantages that the number of board manufacturing processes is increased compared to the standard multilayer wiring board, which is a factor in increasing costs. It was. In addition, in the multilayer wiring board of 6 layers and 8 layers as shown in FIG. 6 and FIG. 7, when the interlayer is thickened, the thickness of the other layers must be extremely narrowed, and the insulation between the layers is impaired. In some cases, production was impossible.

  The present invention has been made to solve such problems, and its purpose is to guarantee a separation distance defined by intrinsically safe explosion-proofing while using a standard multilayer wiring board. An object of the present invention is to provide a multilayer wiring board capable of satisfying the requirements.

In order to achieve such an object, the present invention uses a hardened insulating fat as a core material, a semi-cured insulating material as a prepreg, a surface layer formed by laminating the core material and the prepreg, and In a multilayer wiring board where the inner layer is a printed wiring surface and the distance in the thickness direction between the printed wiring surfaces of adjacent layers is less than the separation distance specified by the intrinsically safe explosion-proof standard , the surface layer and the printed wiring surface of the inner layer are , to avoid the inside distance defined in intrinsic safety standards from the wiring pattern formed on the printed wiring surface of the adjacent layer located, wherein the wiring pattern is formed.

  In the present invention, when forming a wiring pattern on the printed wiring surface of the surface layer and the inner layer of the multilayer wiring board, the separation distance defined by intrinsic safety explosion protection from the wiring pattern formed on the printed wiring surface of the adjacent layer. A wiring pattern is formed at a position avoiding the inside. That is, in the present invention, the wiring pattern is not formed within the separation distance defined by the intrinsic safety explosion protection from the wiring pattern of the adjacent layer. As a result, it is possible to secure a separation distance defined by intrinsically safe explosion-proof without changing the thickness of the prepreg or the core material, and a standard specification multilayer wiring board can be used as it is.

  According to the present invention, the wiring pattern is formed at a position that avoids the distance defined by the intrinsically safe explosion-proof from the wiring pattern formed on the printed wiring surface of the adjacent layer. It is possible to secure the separation distance specified by intrinsically safe explosion-proof without changing the thickness of the core material, and guarantee the separation distance prescribed by intrinsically safe explosion-proof while using the standard multilayer wiring board. It becomes possible to do.

It is a figure which shows the principal part of one Embodiment (4-layer wiring board of a standard specification) of the multilayer wiring board which concerns on this invention. It is a figure which illustrates the wiring pattern formed in the surface layer and inner layer of the multilayer wiring board shown in FIG. It is a figure which shows an example of the conventional multilayer wiring board. It is a figure which illustrates the wiring pattern formed in the surface layer and inner layer of the conventional multilayer wiring board. It is a figure which shows the structural example (4 layer wiring board) of the standard specification of a multilayer wiring board. It is a figure which shows the structural example (6 layer wiring board) of the standard specification of a multilayer wiring board. It is a figure which shows the structural example (8-layer wiring board) of the standard specification of a multilayer wiring board.

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

  FIG. 1 is a diagram showing a main part of an embodiment of a multilayer wiring board according to the present invention. This multilayer wiring board is a four-layer wiring board having the same standard specifications as shown in FIG. 5, and has a laminated structure in which a core material 1-1 is sandwiched between a prepreg 2-1 and a prepreg 2-2.

  That is, the upper surface of the prepreg 2-1 is the surface layer (first layer) L1, the layer between the prepreg 2-1 and the core material 1-1 is the inner layer (second layer) L2, and the core material 1-1 and the prepreg 2 −1 is the inner layer (third layer) L3, and the lower surface of the prepreg 2-2 is the surface layer (fourth layer) L4.

  In addition, the core material 1-1 is a cured glass epoxy resin, the prepreg 2-1 is a semi-cured glass epoxy resin, and the core material 1-1 and the prepregs 2-1 and 2-2 are stacked. By performing the heating and pressurizing treatment, the prepregs 2-1 and 2-2 are bonded to the core material 1-1 and are cured glass epoxy resins.

  The surface layers L1 and L4 and the inner layers L2 and L3 are used as printed wiring surfaces, and various wiring patterns including component pads are formed on the printed wiring surface.

  In order to distinguish the four-layer wiring board 101 shown in FIG. 5 from the four-layer wiring board 101 shown in FIG. 1, the four-layer wiring board 101 shown in FIG. The four-layer wiring board 101 shown is 101A.

  In the present embodiment, when the wiring patterns are formed on the printed wiring surfaces of the surface layers L1, L4 and the inner layers L2, L3 of the four-layer wiring board 101A, the wiring patterns formed on the printed wiring surfaces of the adjacent layers. The wiring pattern is formed at a position avoiding the distance d defined by intrinsically safe explosion protection. That is, a wiring pattern is not formed within a separation distance defined by intrinsically safe explosion protection from wiring patterns of adjacent layers.

  FIG. 2A illustrates a wiring pattern formed on the surface layer L1, and FIG. 2B illustrates a wiring pattern formed on the inner layer L2. In FIG. 2, black portions are wiring patterns including component pads formed of copper foil.

In FIG. 2, when attention is paid to the regions S1 ₁ and S1 ₂ as one of the regions where the wiring pattern of the surface layer L1 is formed, the separation distance defined by the intrinsically safe explosion of the regions S2 ₁ and S2 ₂ in the inner layer L2 within d (distance d from the wiring pattern formed in the area S1 ₁ and S1 _2), the wiring pattern is not formed. That is, the wiring pattern is formed at a position avoiding the distance d.

  As described above, in the present embodiment, the wiring pattern is formed at a position avoiding the distance d defined in the intrinsically safe explosion-proof from the wiring pattern formed on the printed wiring surface of the adjacent layer. Therefore, it is possible to secure the separation distance d defined by intrinsically safe explosion-proof without changing the thickness of the prepregs 2-1 and 2-2 and the core material 1-1. The separation distance d defined by intrinsically safe explosion-proof can be assured while using the wiring board 101A.

  In the above-described embodiment, an example using a standard specification four-layer wiring board has been described, but a multi-layer wiring board such as a standard specification six-layer or eight-layer wiring board is similar to the standard specification four-layer wiring board. The configuration can be adopted.

  In standard specification multilayer wiring boards such as 6 layers and 8 layers, not only between the surface layer and the inner layer, but also between the inner layer and the inner layer, the wiring formed on the printed wiring surface of the adjacent layer A wiring pattern is formed at a position avoiding the distance d defined by intrinsically safe explosion-proof from the pattern.

  This makes it possible to secure the separation distance d defined by intrinsically safe explosion-proofing without changing the thickness of the prepreg or core material, even for standard multilayer wiring boards with 6 or 8 layers. The separation distance d defined by the intrinsically safe explosion-proof can be ensured while using the multilayer wiring board such as 6 layers and 8 layers.

[Extension of the embodiment]
The present invention has been described above with reference to the embodiment. However, the present invention is not limited to the above embodiment. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the technical idea of the present invention.

1-1 ... Core material, 2-1, 2-2 ... Pre-preg, L1, L4 ... Surface layer, L2, L3 ... Inner layer, 101 (101A) ... Multi-layer wiring board (standard four-layer wiring board), S1 _{1, S1 2, S2 1,} S2 2 ... region.

Claims (2)

The insulating material in a cured state is used as a core material, the insulating material in a semi-cured state is used as a prepreg, the surface layer and the inner layer formed by laminating the core material and the prepreg are used as printed wiring surfaces, and adjacent layers are printed. In multilayer wiring boards where the distance in the thickness direction between the wiring surfaces is less than the separation distance specified in the intrinsically safe explosion-proof standard ,
The surface layer and the printed wiring surface of said inner layer,
Multi-layer wiring board, characterized in that the avoided in separation distance from the wiring pattern formed on the printed wiring surfaces of adjacent layers are defined by the intrinsic safety standards position, the wiring pattern is formed . In the multilayer wiring board according to claim 1,
The said insulating material is a glass epoxy resin. The multilayer wiring board characterized by the above-mentioned.

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