TWI386113B - Circuit board - Google Patents

Description

Circuit board

The present invention relates to a circuit board and a design method thereof, and more particularly to a circuit board having high-quality signal transmission capability and a design method of the same.

The printed circuit board usually comprises a substrate composed of an insulating layer and a copper foil, and the insulating layer is generally formed by being immersed in a thermosetting resin by an insulating cloth (for example, a glass cloth or the like).

As shown in FIG. 1 and FIG. 2, a signal line 17 is disposed on the insulating layer 1 of the printed circuit board, and an insulating cloth 10 is disposed in the insulating layer 1. The insulating cloth 10 is a fiber line 11 which is generally disposed in the industry. And the longitudinally disposed fiber strands 12 are woven by a plain weave method, and the transverse and longitudinal fiber strands 11 and 12 are simultaneously formed on the insulating cloth into a plurality of gaps 13 arranged in a neat manner, and the resin is filled in the gaps 13 In the middle, the fiber strands 11, 12 and the resin usually have different dielectric constants. For example, the dielectric fiber used generally has a dielectric constant of about 6.6, and the dielectric constant of the resin is about 3.2. On the other hand, the signal of the printed circuit board The signal line 17 disposed on the line layer generally has a plurality of orientations, such as 0°, 45°, 90°, -45°, etc., which are usually used. Therefore, sometimes the signal line 17 is positive on the insulating cloth 10. The projection coincides with the fiber line 11 or 12 (as shown in Fig. 1 at 0° and 90°), and sometimes the signal line 17 is projected onto the insulating cloth 10 through the resin in the gap 13 (Fig. 1). Zhongcheng positive and negative 45° wiring signal line), because fiber lines 11, 12 and resin 13 have The dielectric constant, the impedance value of the layout of the signal lines as many as in the above case of having a large difference, so that different channels The signal between the lines has different delays, which affects the signal transmission quality. When a bent signal line is laid, the impedance value of one segment of the signal line may be larger, and the impedance value of the other segment is smaller. The transmission impact is more serious.

In view of the above, it is necessary to provide a circuit board provided with a signal line having a stable impedance value.

A circuit board comprising an insulating layer, wherein the insulating layer is provided with a plurality of signal wires, wherein the insulating layer is provided with a layer of insulating cloth, the insulating cloth is composed of fiber wires, and the plurality of signals are arranged on the insulating layer The orthographic projection of the line on the insulating cloth is not parallel to the fiber line.

A circuit board comprising an insulating layer, at least one signal line is disposed on the insulating layer, and the insulating layer is provided with a layer of insulating cloth, the insulating cloth is composed of fiber lines disposed in a horizontal direction and a longitudinal direction, and each two phases are disposed laterally A square area is formed between a center line of the adjacent fiber line and a center line of each two adjacent fiber lines disposed longitudinally, and an angle between a diagonal line of the square area and a center line of the laterally disposed fiber line is first An angle between the diagonal line of the square area and a center line of the longitudinally disposed fiber line is a second angle, and an orthogonal projection of the at least one signal line on the insulating cloth and a diagonal line of the square area, The angle between the transversely disposed fiber strands and the longitudinally disposed fiber strands is greater than or equal to one-half of the first of the first angle and the second angle.

A circuit board design method includes the following steps: providing an insulating layer, wherein the insulating layer is provided with a layer of insulating cloth, the insulating cloth Forming a fiber line disposed laterally and longitudinally; laying a plurality of signal lines on the insulating layer; and rotating the insulating cloth or the plurality of signal lines by an angle to make the plurality of signal lines positive on the insulating cloth The projection is not parallel to the fiber lines of the lateral arrangement and the longitudinal arrangement.

Compared with the prior art, the orthographic projection of the signal line on the insulating board of the present invention on the insulating cloth is not parallel to the fiber line, so that the signal line has a stable impedance value and improves the signal transmission quality.

Please refer to FIG. 3. FIG. 3 is an enlarged view of the portion III of FIG. 1 . The center line of two adjacent fiber lines 11 disposed transversely on the insulating cloth 10 and the center line of two adjacent fiber lines 12 disposed longitudinally are enclosed. A square area 15 (i.e., the area enclosed by the broken line in Fig. 3), the distance between the center lines of two adjacent fiber lines 11 disposed laterally on the insulating cloth 10 is L = 45.36 × 10 ^-3 cm (i.e., 17.86 × 10 ^{- 3} inches), the distance between the center lines of two adjacent fiber lines 12 disposed longitudinally is W=45.36×10 ^-3 cm (ie, 17.86×10 ^-3 inches), and the center line and the square area of the transversely disposed fiber line 11 The angle between the diagonals of 15 is φ=arc tan L/W=45°, and the angle between the center line of the longitudinally disposed fiber line 12 and the diagonal of the square area 15 is θ=90°-φ=45°. If an angle α is equal to half of the smaller of φ and θ, in an embodiment of the invention, α = min(θ, φ)/2 = 22.5°, and the insulating cloth 10 of FIG. 1 is opposed to the signal line 17. The board layout in Fig. 4 can be obtained by rotating 22.5° counterclockwise. The angle between the orthographic projection of the signal line 17 on the insulating cloth 10 and the diagonal lines of the fiber lines 11, 12 and the square area 15 in Fig. 4 Greater than or equal At 22.5°, that is, the orthographic projection of the signal line 17 on the insulating cloth 10 is not parallel to the diagonal lines of the fiber lines 11, 12 or the square region 15, preventing the signal line 17 from having a large impedance change, thereby improving signal transmission. quality. According to the concept of the present invention, the insulating cloth can also be rotated by a degree in the counterclockwise direction, or the signal line can be rotated by a degree in the clockwise or counterclockwise direction relative to the insulating cloth, and the degree of α is only a preferred value, as long as the rotation is performed. The purpose of the present invention is achieved by the angle and direction such that the orthographic projection of signal line 17 on insulating cloth 10 is not parallel to the diagonal of any of fiber lines 11, 12 or square regions 15.

Referring to FIG. 5 and FIG. 6, which is another preferred embodiment of the present invention, FIG. 5 shows another insulating cloth 30, and the distance between the center lines of two adjacent fiber lines 31 disposed laterally on the insulating cloth 30. L' = 54.05 × 10 ^-3 cm (i.e., 21.28 × 10 ^-3 inches), and the distance W' = 42.34 × 10 ^-3 cm (i.e., 16.67 × 10 ^{-3 )} between the center lines of two adjacent fiber lines 32 disposed longitudinally Inches), the center line of two adjacent fiber lines 31 disposed laterally on the insulating cloth 30 and the center line of two adjacent fiber lines 32 disposed longitudinally together form a square area 35 (ie, the area enclosed by the broken line in FIG. 5) ), the angle φ'=arc tan L'/W'=52° between the center line of the laterally disposed fiber line 31 and the diagonal line of the square area 35, the center line and the square area of the longitudinally disposed fiber line 32) The angle θ' between the diagonals of 35 is 90°-φ'=38°, and an angle α' is one of the smaller of the above two angles, then α'=19°, the relative insulation signal of the insulating cloth 30 When the line 37 is rotated 19° counterclockwise, the angle between the orthographic projection of the signal line 37 on the insulating cloth 30 and the diagonal line of each of the fiber lines 31, 32 or the square area 35 is greater than or equal to 19°, and the signal line 37 is Insulating cloth 3 The orthographic projection on 0 is not parallel to the diagonal of any of the fiber lines 31, 32 or the square region 35, preventing the signal line 37 from having a large impedance change, thereby improving the transmission quality of the signal.

Experiment with the insulating cloth 30, before the implementation of the present invention, the plurality of signal lines horizontally laid on the substrate, such as the positive projection of the signal line on the insulating cloth coincides with the fiber line, and the signal delay thereon is 152.8×10 ^-12 seconds. The signal line per inch, which does not coincide with the fiber line, has a signal delay of 148.6 × 10 _-12 seconds per inch, which differs by 4.2 × 10 ^-12 seconds per inch, for example, horizontally on the substrate. A pair of signal lines are arranged, each of which is 2 inches long. One of the signal lines on the insulating cloth has an orthographic projection coincident with the fiber line, and the other one does not coincide. The signal delay time on the two signal lines differs by 8.4×10 ^-12 seconds. After implementing the present invention, the signal delay on the signal line disposed horizontally is 150.3×10 ^-12 seconds per inch, and remains substantially unchanged, and the signal delay on the signal line disposed at a 45 degree angle is 150.4×10 ^-12 seconds. The signal delay of the signal line laid in the horizontal direction per inch and the signal line laid at a 45 degree angle differs by only 0.1 × 10 ^-12 seconds per inch. As can be seen from the above information, with the present invention, the signal transmission quality on the signal line is significantly improved.

In summary, the present invention is in accordance with the conditions of the invention patent application, and the patent application is filed according to law. The above description is only the preferred embodiment of the present invention, and equivalent modifications or variations made by those skilled in the art to the spirit of the present invention should be included in the following claims.

1‧‧‧Insulation

10‧‧‧Insulation cloth

11, 12‧‧‧ fiber line

13‧‧‧ gap

15‧‧‧ square area

17‧‧‧ signal line

30‧‧‧Insulation cloth

31, 32‧‧‧ fiber line

35‧‧‧ square area

37‧‧‧ signal line

1 is a schematic view showing an insulating cloth and a signal line of a circuit board in the prior art.

Figure 2 is a cross-sectional view taken along line II-II of Figure 1.

Figure 3 is an enlarged view of the portion III in Figure 1.

4 is a schematic view showing an insulating cloth and a signal line of a preferred embodiment of the circuit board of the present invention.

Figure 5 is a schematic view of another insulating cloth.

Figure 6 is a schematic view of another preferred embodiment of the present invention which is provided with signal lines on the insulating cloth of Figure 5.

10‧‧‧Insulation cloth

11, 12‧‧‧ fiber line

17‧‧‧ signal line

Claims (5)

A circuit board comprising an insulating layer, wherein the insulating layer is provided with a plurality of signal wires, wherein the insulating layer is provided with a layer of insulating cloth, the insulating cloth is composed of fiber wires, and the plurality of signal wires disposed on the insulating layer are The orthographic projection on the insulating cloth is not parallel to the fiber line, and the fiber lines are respectively disposed in the horizontal or vertical direction, and the center line of each two adjacent fiber lines disposed laterally and the center of each two adjacent fiber lines disposed longitudinally Forming a square area between the lines, the orthogonal projection of the plurality of signal lines on the insulating cloth is not parallel to the diagonal of the square area, and the diagonal line of the square area and the center of the transversely disposed fiber line The angle between the lines is a first angle, the angle between the diagonal line of the square area and the center line of the longitudinally disposed fiber line is a second angle, and the orthographic projection of the plurality of signal lines on the insulating cloth The angle between the transversely disposed fiber line of the square region and the longitudinally disposed fiber line is greater than or equal to one of the smaller of the first angle and the second angle. The circuit board of claim 1, wherein the insulating cloth is a fiberglass cloth. A circuit board design method comprising the steps of: providing an insulating layer, wherein the insulating layer is provided with a layer of insulating cloth, wherein the insulating cloth is composed of transversely disposed and longitudinally disposed fiber strands, and each two adjacent fiber strands are disposed laterally Forming a square area between a center line and a center line of each two adjacent fiber lines disposed longitudinally, and an angle between a diagonal line of the square area and a center line of the laterally disposed fiber line is a first angle, An angle between a diagonal line of the square area and a center line of the longitudinally disposed fiber line is a second angle; a plurality of signal lines are disposed on the insulating layer; Rotating the insulating cloth or the plurality of signal lines by an angle, the insulating cloth or the plurality of signal lines rotating at an angle substantially equal to one of a smaller one of the first angle and the second angle, and The orthographic projection of the complex signal line on the insulating cloth is not parallel to the transversely disposed and longitudinally disposed fiber lines. The circuit board design method of claim 3, wherein after the insulating cloth or the plurality of signal lines are rotated, the orthogonal projection of the plurality of signal lines on the insulating cloth and the diagonal of the square area are also Not parallel. The method of designing a circuit board according to claim 3, wherein the insulating cloth is a glass cloth.