Printed wiring board and method for manufacturing printed wiring board

Abstract

To provide a printed wiring board with reduced insertion loss by reducing the difference between the wiring length of first wiring and the wiring length of second wiring constituting the printed wiring board and shortening a wiring length adjustment wiring.SOLUTION: A printed wiring board including a substrate, an electronic component, and a plurality of wirings includes first wiring and second wiring as the plurality of wirings, and the second wiring includes wiring for wiring length adjustment to make the length of the first wiring and the length of the second wiring substantially the same between the second apex of the electronic component and the outer edge of the board that is closest to and facing the second apex of the electronic component.SELECTED DRAWING: Figure 1A

Description

[Technical Field]

[0001] The present invention relates to a printed wiring board and a method for manufacturing a printed wiring board. [Background technology]

[0002] Patent Document 1 discloses an electronic component mounting board. According to Patent Document 1, signal lines are formed on the surface side of the electronic component mounting board, and most of the signal lines extend radially toward the outer periphery of the board. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 9-18097 Summary of the Invention [Problem to be solved by the invention]

[0004] A conventional printed wiring board is formed by mounting an electronic component (IC) at the center of the electronic component mounting surface of a package (PKG) substrate. The electronic component is mounted on the electronic component mounting surface of the package (PKG) substrate so that each side constituting the outer edge of the electronic component is parallel to each side constituting the outer edge of the package (PKG) substrate.

[0005] FIG. 4 is a diagram illustrating a conventional printed wiring board. On printed wiring board 7, multiple wirings are formed radially from electronic component (IC) 9 toward the outer edge of package (PKG) substrate 8. The multiple wirings consist of first wiring 10 and second wiring 11. Wiring 10 is formed from a corner of the electronic component toward a corner of package (PKG) substrate 8. Wiring 11 is formed from approximately the center of the outer edge of electronic component 9 toward approximately the center of the outer edge of package (PKG) substrate 8. Therefore, wiring 11 is shorter than wiring 10. In other words, the wiring length of wiring 10 and the wiring length of wiring 11 are not the same, so the impedance of wiring 10 does not match the impedance of wiring 11.

[0006] Therefore, in order to match the impedance of wiring 10 with the impedance of wiring 11, length-adjusting wiring 12 is added to wiring 11 so that the wiring length of wiring 11 is the same as the wiring length of wiring 10. However, adding length-adjusting wiring 12 to wiring 11 increases the resistance of wiring 11. As a result, the insertion loss of printed wiring board 7 increases.

[0007] The present invention has been made in consideration of these technical circumstances, and aims to provide a printed wiring board in which insertion loss is reduced by reducing the difference between the wiring length of the first wiring and the wiring length of the second wiring that constitute the printed wiring board and shortening the wiring length adjustment wiring. [Means for solving the problem]

[0008] A printed wiring board according to the present invention is a printed wiring board including a substrate, an electronic component, and a plurality of wirings, the electronic component is mounted at the center of the electronic component mounting surface of the substrate, and has an electronic component first vertex and an electronic component second vertex at an electronic component outer edge portion of the electronic component; The plurality of wirings a first wiring that connects a central portion of the electronic component outer edge located between the first vertex of the electronic component and the second vertex of the electronic component to a substrate outer edge portion of the substrate that faces the second vertex of the electronic component closest to the electronic component; a second wiring that connects the second vertex of the electronic component and a central portion of the outer edge of the substrate that faces the second vertex of the electronic component closest to the second vertex of the electronic component; the first wiring bends in the direction of the substrate outer edge portion that faces closest to the electronic component second vertex at a bending point where a first straight line connecting the electronic component outer edge center portion and a first substrate vertex of the substrate that faces closest to the electronic component outer edge center portion intersects with a third straight line that is parallel to a second straight line connecting the substrate first vertex and the substrate second vertex that constitutes the substrate outer edge portion that faces closest to the electronic component second vertex and that passes through the electronic component second vertex; The second wiring has a wiring length adjustment wiring between the second vertex of the electronic component and the outer edge of the substrate that is closest to and faces the second vertex of the electronic component, for making the length of the first wiring and the length of the second wiring approximately equal.

[0009] The method for manufacturing a printed wiring board according to the present invention is the method for manufacturing the printed wiring board described above, Mounting the electronic component at the center of an electronic component mounting surface of a substrate; forming a first wiring between a central portion of an outer edge of the electronic component and a substrate outer edge portion of the substrate that faces closest to the second vertex of the electronic component; forming a second wiring between the second vertex of the electronic component and a central portion of the outer edge of the substrate that is closest to and faces the second vertex of the electronic component; The method includes forming a wiring length adjusting wiring in the second wiring to make the length of the first wiring and the length of the second wiring substantially the same. [Effects of the Invention]

[0010] According to the present invention, by reducing the difference between the wiring length of the first wiring and the wiring length of the second wiring that constitute the printed wiring board and shortening the wiring length adjustment wiring, it is possible to provide a printed wiring board with reduced insertion loss. [Brief explanation of the drawings]

[0011] [Figure 1A] 1 is a top view illustrating a printed wiring board according to an embodiment of the present invention. [Figure 1B] 2 is a cross-sectional view of a printed wiring board taken along line X and Y according to an embodiment of the present invention. FIG. [Figure 2] 1A and 1B are diagrams for explaining in detail a printed wiring board according to an embodiment of the present invention; [Figure 3A] 1A to 1C are diagrams illustrating a step in a method for manufacturing a printed wiring board according to an embodiment of the present invention. [Figure 3B] 1A to 1C are diagrams illustrating a step in a method for manufacturing a printed wiring board according to an embodiment of the present invention. [Figure 3C] 1A to 1C are diagrams illustrating a step in a method for manufacturing a printed wiring board according to an embodiment of the present invention. [Figure 4] 1A and 1B are diagrams illustrating an embodiment of a conventional printed wiring board. DETAILED DESCRIPTION OF THE INVENTION

[0012] FIG. 1 is a schematic diagram illustrating a printed wiring board according to one embodiment of the present invention. FIG. 1A is a top view, and FIG. 1B is a cross-sectional view taken along the line X and Y in FIG. 1A. As shown in FIG. 1A, the printed wiring board 1 according to this embodiment includes a package (PKG) substrate 2 (hereinafter simply referred to as "substrate 2"), an electronic component (IC) 3, and multiple wirings. The multiple wirings include a first wiring 4 and a second wiring 5. The electronic component 3 is mounted at the center of a mounting surface 21 of the substrate 2. The area of ​​the mounting surface 21 directly below the electronic component 3 is referred to as the mounting area A. The second wiring 5 includes a wiring length adjustment wiring 6 for adjusting its length to approximately the same as the length of the first wiring 4. The first wiring 4 may be composed of multiple wirings, as long as its length is approximately the same as the length of the second wiring 5. The first wiring 4 and the second wiring 5 are formed by known methods such as a subtractive method or an additive method.

[0013] As shown in FIG. 1B, the substrate 2 has a mounting surface 21 and a back surface S opposite the mounting surface 21. As shown in FIG. 1B, the substrate 2 has a plurality of conductor layers D and an insulating layer I between adjacent conductor layers D. Adjacent conductor layers D are connected by via conductors V that penetrate the insulating layer I. As shown in FIG. 1B, the wiring 4 extends from the mounting area A toward the periphery of the back surface S. In FIG. 1B, the wiring length adjustment wiring 6 is formed within one conductor layer. However, the wiring length adjustment wiring 6 may be formed across two or more conductor layers.

[0014] FIG. 2 is a diagram illustrating in detail a printed wiring board according to one embodiment of the present invention. As shown in FIG. 2, an electronic component 3 mounted at the center of the mounting surface 21 of the substrate 2 has an electronic component first vertex 32 and an electronic component second vertex 33 at its electronic component outer edge 31. The electronic component outer edge 31 has an electronic component outer edge center 3M at the center between the electronic component first vertex 32 and the electronic component second vertex 33. The shape of the electronic component 3 is not particularly limited as long as it has a first vertex and a second vertex adjacent to the first vertex. Examples of the shape of the electronic component 3 include a square and a rectangle.

[0015] The wire 4 of the first wiring extends from the electronic component outer edge center portion 3M toward the substrate outer edge portion 22 of the substrate 2 that faces closest to the electronic component second vertex 33. The wire 4 of the first wiring is bent toward the substrate outer edge portion 22 that faces closest to the electronic component second vertex 33, using the bending point P as a reference point.

[0016] The wiring 4 of the first wiring is composed of a substrate inside wiring 41 and a substrate outside wiring 42, with a bending point P as a reference point. Here, the bending point P is the point where a first straight line L1 connecting the electronic component outer edge center 3M and the substrate first vertex 23 of the substrate 2 that faces the electronic component outer edge center 3M closest to the electronic component outer edge center 3M intersects with a third straight line L3 that is a straight line parallel to a second straight line L2 connecting the substrate first vertex 23 and the substrate second vertex 24 that constitute the substrate outer edge 22 that faces the electronic component second vertex 32 closest to the electronic component second vertex 32 and passes through the electronic component second vertex 33.

[0017] The wiring 4 of the first wiring is inclined at an angle of 40 to 50 degrees relative to the first straight line L1 toward the second vertex 33 of the electronic component, and is bent toward the substrate outer edge 22 of the substrate 2 so that the angle formed with the electronic component outer edge 31 is approximately 135 degrees. Note that the outer edge shape of the substrate 2 and the outer edge shape of the electronic component 3 must be in a similar relationship. This is because if the outer edge shapes of the substrate 2 and the electronic component 3 are not in a similar relationship, the bend P does not exist on the line of the first straight line L1.

[0018] The wires 5 of the second wiring are formed between the electronic component second vertex 33 and the board outer edge center 2M of the board 2 that faces closest to the electronic component second vertex 33. Here, the electronic component 3 needs to be mounted in the center of the board 2. The reason for this is that if the electronic component 3 is not mounted in the center of the board 2, the wires 5 of the second wiring cannot reach the board outer edge center 2M. The wires 5 of the second wiring are bent so that the angle formed with the electronic component outer edge 31 is approximately 135°, and head toward the board outer edge center 2M of the board 2.

[0019] The wire 5 of the second wiring has a wire length adjustment wire 6 for making the length of the wire 4 of the first wiring and the length of the wire 5 of the second wiring approximately equal between the electronic component second vertex 33 and the substrate outer edge 22 that faces the electronic component second vertex 33 closest to the electronic component second vertex 33. The wire 5 of the second wiring is composed of a substrate inner wire 51, a wire length adjustment wire 6, and a substrate outer wire 52. The shape of the wire length adjustment wire 6 is not particularly limited, and a meander wire or other shape can be adopted.

[0020] The wire 4 of the first wiring is formed by bending, with the bending point P as the reference point, in the direction of the substrate outer edge 22 that faces and is closest to the electronic component second vertex 33. Therefore, by reducing the difference in length between the wire 4 of the first wiring and the wire 5 of the second wiring, the wire length adjustment wire 6 can be shortened.

[0021] As a result, even if a wiring length adjustment wiring 6 is added to the wiring 5 of the second wiring, the resistance of the wiring 5 of the second wiring can be prevented from increasing, and the insertion loss of the printed wiring board 1 can be reduced.

[0022] Furthermore, in the printed wiring board 1 according to one embodiment of the present invention, the positional relationship between the electronic component 3 and the substrate 2 can be set as follows in order to shorten the wiring length adjustment wiring 6 by reducing the difference between the length of the wiring 4 of the first wiring and the length of the wiring 5 of the second wiring.

[0023] First, a reference state is established in which electronic component outer edge 31, formed by electronic component first vertex 32 and electronic component second vertex 33, and substrate outer edge 22, formed by substrate first vertex 23 and substrate second vertex 24, are parallel to each other. Next, electronic component 3 is positioned on substrate 2 so that electronic component first vertex 32 and electronic component second vertex 33 are rotated 40 to 50 degrees around the fixed axis, with the center of electronic component 3 as the fixed axis. If the angle by which electronic component first vertex 32 and electronic component second vertex 33 rotate around the center of electronic component 3 as the fixed axis falls within the above range, this is preferable because it reduces the difference in length between wire 4 of the first wiring and wire 5 of the second wiring.

[0024] Furthermore, in the printed wiring board 1 according to one embodiment of the present invention, it is preferable that the shape of the electronic component 3 is approximately square. If the shape of the electronic component 3 is approximately square, it is preferable because it is easy to design the length of the wire 4 of the first wiring and the length of the wire 5 of the second wiring to be approximately the same. Since the shape of the electronic component 3 of the printed wiring board 1 according to this embodiment is approximately square, it can also be suitably used as a package (PKG) substrate for a CPU, etc.

[0025] 3A to 3C are diagrams illustrating the steps of one embodiment of a method for manufacturing a printed wiring board according to the present invention. In the example shown in FIGS. 3A to 3C, the dimensions of each component are shown differently from the actual dimensions in order to better understand the features of the present invention. Hereinafter, one embodiment of a method for manufacturing a printed wiring board according to the present invention will be described with reference to FIGS. 3A to 3C.

[0026] 3A, electronic component 3 is positioned at the center of mounting surface 21 of substrate 2. Next, wiring including first wiring 4, second wiring 5, and wiring length adjustment wiring 6 is formed on substrate 2 as described below. Thereafter, electronic component 3 is positioned so that its center coincides with the center of mounting surface 21 of substrate 2, and electronic component 3 is mounted on mounting surface 21 of substrate 2. Positioning of electronic component 3 relative to mounting surface 21 of substrate 2 may be performed by rotating electronic component first vertex 32 and electronic component second vertex 33 by 40 to 50 degrees around the center of electronic component 3 as a fixed axis, based on a state in which electronic component outer edge 31 formed by electronic component first vertex 32 and electronic component second vertex 33 is parallel to substrate outer edge 22 formed by substrate first vertex 23 and substrate second vertex 24.

[0027] 3B, the wiring 4 of the first wiring is formed on the mounting surface 21 of the substrate 2. The wiring 4 of the first wiring is formed between the central portion 3M of the outer edge of the electronic component and the substrate outer edge portion 22 of the substrate 2 that faces closest to the second vertex 33 of the electronic component.

[0028] The wiring 4 of the first wiring is formed by bending in the direction of the substrate outer edge portion 22 that faces closest to the electronic component second vertex 33, at a bending point P where a first straight line L1 connecting the electronic component outer edge center 3M and the substrate first vertex 23 of the substrate 2 that faces closest to the electronic component outer edge center 3M intersects with a second straight line L2 connecting the substrate first vertex 23 and the substrate second vertex 24 that constitute the substrate outer edge portion 22 that faces closest to the electronic component second vertex 33, and a third straight line L3 that passes through the electronic component second vertex 33.

[0029] Next, as shown in FIG. 3C , the wiring 5 of the second wiring is formed on the mounting surface 21 of the substrate 2. The wiring 5 of the second wiring is formed between the second vertex 33 of the electronic component and the central portion 2M of the outer edge of the substrate that is closest to and faces the second vertex 33 of the electronic component. The wiring 5 of the second wiring has a wiring length adjustment wiring 6 formed therein to make the length of the wiring 4 of the first wiring and the length of the wiring 5 of the second wiring approximately equal. After measuring the length of the wiring 4 of the first wiring, the length and shape of the wiring length adjustment wiring 6 are set based on the measured length of the wiring 4 of the first wiring. The shape of the wiring length adjustment wiring 6 may be a meander wiring or the like.

[0030] Thus, according to the method for manufacturing a printed wiring board of the present invention, it is possible to obtain a printed wiring board 1 in which the difference in length between the wires 4 of the first wiring and the wires 5 of the second wiring is small. The printed wiring board obtained by the method for manufacturing a printed wiring board of the present invention has short wire length adjustment wires 6, which allows for reduced insertion loss.

[0031] Example 1 In the method for manufacturing a printed wiring board according to an embodiment of the present invention, a square (50 mm × 50 mm) package substrate was used as the substrate 2, and a square (10 mm × 10 mm) IC was used as the electronic component 3. The electronic component (IC) was mounted on the mounting surface of the package substrate so that its outer edge was tilted approximately 45° leftward relative to the outer edge of the package substrate. A first trace, trace I, was initially drawn out from the electronic component (IC) at a right angle to the outer periphery of the electronic component (IC), passed through the apex of the electronic component (IC), and when it met a straight line parallel to the outer periphery of the package substrate, trace I was bent approximately 45° rightward and formed toward the outer edge of the package substrate. A second trace, trace II, was formed between the outer edge of the electronic component (IC) and the outer edge of the package substrate. A length-adjusting trace was provided in trace II as a trace for adjusting the trace length. The length of trace I was measured, and trace II was formed based on the measured length of trace I. In Example 1, the difference between the length of wiring I and the length of wiring II was measured and found to be 5.0 mm. Furthermore, the insertion loss of the printed wiring board obtained in Example 1 was evaluated. The results are shown in Table 1.

[0032] (Comparative Example 1) In the method for manufacturing a printed wiring board of Comparative Example 1 of the present invention, a printed wiring board was manufactured in the same manner as in Example 1, except that the outer edge of the PKG substrate and the outer edge of the electronic component (IC) were parallel to each other and wiring I was formed radially from the electronic component (IC) toward the outer periphery of the PKG substrate. In Comparative Example 1, the difference in length between wiring I and wiring II was measured and found to be 8.3 mm. Furthermore, the insertion loss of the printed wiring board obtained in Comparative Example 1 was evaluated. The results are shown in Table 1.

[0033] [Table 1]

[0034] According to Table 1, it was found that by arranging an electronic component (IC) on the mounting surface of the PKG substrate so that the outer edge of the electronic component is inclined approximately 45° left with respect to the outer edge of the PKG substrate, and by forming wiring I and wiring II on the PKG substrate, the difference in length between wiring I and wiring II can be reduced. Specifically, in the printed wiring board 1 obtained in Comparative Example 1, the difference in length between wiring I and wiring II was 8.3 mm, whereas in the printed wiring board 1 obtained in Example 1, the difference in length between wiring I and wiring II was 5.0 mm. It was also found that the printed wiring board 1 obtained in Example 1 was capable of reducing insertion loss.

[0035] In this way, the printed wiring board according to the present invention can reduce the difference in wiring length between the first wiring and the second wiring that constitute the printed wiring board, resulting in a printed wiring board with reduced insertion loss.

[0036] Although the above description is based on the illustrated embodiment, the printed wiring board and the method for manufacturing the printed wiring board according to the present invention are not limited to the above embodiment and can be modified as appropriate within the scope of the claims. The printed wiring board and the method for manufacturing the printed wiring board according to the present invention can be applied not only to LGA-type electronic components in which lands are arranged on the underside, but also to printed wiring boards mounted with, for example, SOP-type electronic components in which leads extend from two side surfaces. [Explanation of symbols]

[0037] 1. Printed wiring board 2. Substrate (package (PKG) substrate) 21 Mounting surface S back A. Mounting area D Conductor layer V via conductor I Insulation layer 22 Outer edge of board 23 First vertex of the substrate 24 Second vertex of the board 25 First end of outer edge of substrate 26 Second end of outer edge of substrate 2M Center of outer edge of board L1 1st straight line L2 2nd straight line L3 3rd straight line P bending point 3 Electronic components (IC) 31 Outer edge of electronic components 32 Electronic Components No. 1 33 Electronic Components No. 2 3M Electronic component outer edge center 4 Wiring of the first wiring 41 Internal wiring of the board 42 Board outer wiring 5 Wiring the second wiring 51 Internal wiring of the board 52 Board outer wiring 6 Wiring for wiring length adjustment

Claims

1. A printed wiring board including a substrate, an electronic component, and a plurality of wirings, the electronic component is mounted at the center of the electronic component mounting surface of the substrate, and has an electronic component first vertex and an electronic component second vertex at an electronic component outer edge portion of the electronic component; The plurality of wirings a first wiring that connects a central portion of an outer edge of the electronic component located between the first vertex of the electronic component and the second vertex of the electronic component to a substrate outer edge portion of the substrate that faces the second vertex of the electronic component in the closest position; a second wiring that connects the second vertex of the electronic component and a central portion of the outer edge of the substrate that faces the second vertex of the electronic component closest to the second vertex of the electronic component; the first wiring bends in the direction of the substrate outer edge portion that faces closest to the electronic component second vertex at a bending point where a first straight line connecting the electronic component outer edge center portion and a first substrate vertex of the substrate that faces closest to the electronic component outer edge center portion intersects with a third straight line that is parallel to a second straight line connecting the substrate first vertex and the substrate second vertex that constitutes the substrate outer edge portion that faces closest to the electronic component second vertex and that passes through the electronic component second vertex; the second wiring has a wiring length adjustment wiring between the second vertex of the electronic component and the outer edge portion of the substrate that faces closest to the second vertex of the electronic component, for making the length of the first wiring and the length of the second wiring approximately equal.

2. Based on a state in which the electronic component outer edge portion located between the first vertex of the electronic component and the second vertex of the electronic component and the substrate outer edge portion located between the first vertex of the substrate and the second vertex of the substrate are positioned parallel to each other, 2. The printed wiring board according to claim 1, wherein the first vertex and the second vertex of the electronic component are positioned by rotating the electronic component by 40 to 50 degrees around a center of the electronic component as a fixed axis.

3. The printed wiring board according to claim 1 , wherein the electronic component has a substantially square shape.

4. 2. The method for manufacturing a printed wiring board according to claim 1, Mounting the electronic component at the center of an electronic component mounting surface of a substrate; forming a first wiring between a central portion of an outer edge of the electronic component and a substrate outer edge portion of the substrate that faces closest to the second vertex of the electronic component; forming a second wiring between the second vertex of the electronic component and a central portion of the outer edge of the substrate that is closest to and faces the second vertex of the electronic component; and forming a wiring length adjusting wiring in the second wiring to make the length of the first wiring and the length of the second wiring substantially the same.

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