JP3132495B2 - Printed wiring board and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed wiring board suitable for transmitting a high-frequency signal and a method for manufacturing the same.

[0002]

2. Description of the Related Art When a connector is used to connect printed wiring boards to each other or a printed wiring board and a cable, if the impedance of the connector is not matched, a transmission waveform is generated due to the inductance of the connector itself. Is distorted.

[0003] In recent years, with the increase in the speed of transmission signals within or between information processing apparatuses, reduction in waveform distortion has been required.

In order to meet this demand, for example, Japanese Patent Laid-Open No. 2-94693 discloses a printed wiring board having a through hole.
The hole has a coaxial structure to increase the capacity of the signal line.

That is, in the conventional printed wiring board, as shown in FIGS. 4A and 4B, a hole 6a is formed in a through hole portion of a board 6 having an inner ground layer 5. Hole 6
After forming a, plating 6b is applied to the inside of the hole 6a as shown in FIG.

[0006] Then, as shown in FIG.
4 (e), the signal wiring pattern 4 is formed on the surface layer of the substrate 6 including the insulator 12, as shown in FIG. Then, as shown in FIGS. 4 (f) and 4 (g), after forming the hole 6c in the insulator 12, plating is performed to form the signal line through hole land 2 and the signal line through hole 2c.
To form a rule 3. At this time, the signal line through-hole 3
And the signal wiring pattern 4 are connected.

[0007]

However, in the above-mentioned prior art, in order to manufacture a printed wiring board, FIG.
As shown in (a) to (g), at least seven steps are required. For this reason, although high-frequency characteristics can be improved, there is a problem that the manufacturing cost of the printed wiring board increases.

[0010] As shown in FIG. 5, a connector 7 is connected to the signal line through-hole 3 of the board 6. The equivalent circuit in this case is as shown in FIG.

In FIG. 6, a signal wiring pattern 4 on a substrate 6 has a characteristic impedance Z0, and a connector 7 has an inductance L. The capacity between the connector 7 and the signal line through-hole 3 is C2.
Further, reference numeral 10 indicates a driver circuit, and reference numeral 11 indicates a receiver circuit.

In this case, the equivalent impedance Z of the substrate 6
2 is expressed by the following equation 2. Z2 = √ (L / C2) Equation 2

Here, since there is no capacitive coupling between the signal line through-hole 3 and the ground inner layer 5, the capacitance C2 is
The value of the capacitance C2 becomes small. Therefore, the value of the capacitance C2 increases and decreases in proportion to the number of the inner ground layers 5.

Therefore, when the number of the inner ground layers 5 is small, the value of the capacitance C2 becomes small, so that it is impossible to form a capacitance enough to cancel the inductance L of the connector 7. In this case, the equivalent impedance Z2
Cannot be matched to the characteristic impedance Z0 of the substrate 6, which causes a problem that impedance matching becomes difficult.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and a printed wiring board and its printed wiring board capable of easily achieving impedance matching accompanying the inductance of a connector without increasing manufacturing costs. It is intended to provide a manufacturing method.

[0014]

According to a first aspect of the present invention, there is provided a printed wiring board, wherein a signal wiring pattern is connected to a signal line through hole formed on a board to which a connector is connected via a signal line through hole land. A large-diameter through-hole land formed on an inner layer or an outer layer of the substrate is connected to the signal-line through-hole, and the signal-line through-hole is opposed to the large-diameter through-hole land. And an unconnected ground inner layer is provided.
Patterns for signal wiring pattern and ground inner layer are formed
With a large-diameter through-hole substrate.
Opposition between the land and the part of the opposing inner ground layer
The equivalent impedance of the substrate depends on the change in the capacitance
-The feature is that the dance can be changed . Further, the value of the capacitance can be changed by increasing or decreasing the diameter or area of the large-diameter through-hole land. The method for manufacturing a printed wiring board according to claim 3, wherein the signal wiring pattern is connected to the signal line through hole formed on the board to which the connector is connected via the signal line through hole land. The method
First step of forming a single substrate by laminating double-sided substrates on which patterns such as signal wiring patterns, large-diameter through-hole lands, and ground inner layers are formed, and forming signal line through-holes on a single substrate Forming a hole for the second
A third step of plating the holes, forming signal line through-hole lands and signal line through holes, and connecting the signal wiring pattern and the large-diameter through-hole land ground to the signal line through-holes; S
The inner layer of the ground so that part of it faces Luhole Land
Forming a large-diameter through-hole land and ground inner layer
And a fourth step of providing a capacity between the first step and the second step . Further, the fourth step may include a step of changing the value of the capacitance by increasing or decreasing the diameter or the area of the large-diameter through-hole land. In the printed wiring board and the method of manufacturing the same according to the present invention, a single board is formed by laminating a double-sided board on which a signal wiring pattern, a large-diameter through-hole land, and a ground inner layer are formed. After forming a hole for forming a signal line through hole on the substrate, plating the hole, forming a signal line through hole land and a signal line through hole, and forming a signal wiring pattern and a large diameter through hole on the signal line through hole. Connecting the land ground simplifies the manufacturing process and provides a capacitance between the large-diameter through-hole land and a part of the ground inner layer, and sets the capacitance value to the diameter of the large-diameter through-hole land. Or by changing by increasing or decreasing the area,
The equivalent impedance and the characteristic impedance of the substrate are matched.

[0015]

Embodiments of the present invention will be described below. In the drawings described below, FIGS.
6 are given the same reference numerals.

FIG. 1 is a view showing one embodiment of the printed wiring board of the present invention, FIG. 2 is a process chart showing a method of manufacturing the printed wiring board of FIG. 1, and FIG. 3 is a printed wiring board of FIG. 3 is a diagram showing an equivalent circuit of FIG.

FIG. 1A is a sectional view showing a printed wiring board, FIG. 1B is a view showing signal line through-hole lands and signal wiring patterns, and FIG.
FIG. 1D is a sectional view taken along the line BB ′ of FIG. 1A showing the inner layer of the ground, and FIG. 1D is a sectional view taken along the line AA ′ of FIG. 1A showing a large diameter through-hole land. FIG.

As shown in FIGS. 1 (a) to 1 (d), a large diameter through hole land 1, a signal line through hole land 2, and a signal line through hole 3 are provided on a substrate 6 of a printed wiring board. , A signal wiring pattern 4 and a ground inner layer 5 are provided.

The large diameter through-hole land 1 is connected to a signal line through-hole 3. Signal line through
The hole land 2 and the signal line through-hole 3 are connected to a signal wiring pattern 4.

The ground inner layer 5 is provided above and below the large diameter through-hole land 1. The facing region 8 between the large diameter through-hole land 1 and the inner ground layer 5 is capacitively coupled. Thereby, the capacitive coupling becomes equivalent to that added to the signal line through-hole 3.

Next, a method for manufacturing a printed wiring board having such a configuration will be described with reference to FIGS.

First, as shown in FIG. 2A, a double-sided substrate on which patterns such as a large-diameter through-hole land 1, a signal wiring pattern 4 and a ground inner layer 5 are formed is laminated to form a single substrate. The substrate 6 is formed. Then, as shown in FIG. 2B, a hole 6a for forming the signal line through hole 3 is formed in the substrate 6.

After forming the hole 6a, the hole 6a is plated to form the signal line through hole land 2 and the signal line through hole 3 as shown in FIG. 2 (c).

At this time, the signal line through-hole 3 is
It is connected to the signal wiring pattern 4. In addition, large diameter through-
Hall land 1 is connected to signal line through hole 3. Further, a facing area 8 (see FIG. 1C) between the large diameter through-hole land 1 and the inner ground layer 5 is capacitively coupled.

FIG. 3 shows an equivalent circuit when the connector 7 is connected to the signal line through-hole 3 of the substrate 6 manufactured as described above.

That is, FIG. 3 shows that the signal wiring pattern 4 on the substrate 6 has a characteristic impedance Z0 and the connector 7
Has an inductance L. Further, the capacity between the connector 7 and the signal line through-hole 3 is represented by C1.
And Further, reference numeral 10 indicates a driver circuit, and reference numeral 11 indicates a receiver circuit.

In this case, the equivalent impedance Z1 is expressed by the following equation (1). Z1 = √ (L / C1) Formula 1

Here, the equivalent impedance Z1 changes according to the value of the capacitance C1. The value of the capacitance C1 changes depending on the increase or decrease of the diameter or area of the large-diameter through-hole land 1. Therefore, the equivalent impedance Z1 and the characteristic impedance Z0 of the substrate 6 can be easily matched by increasing or decreasing the diameter or the area of the large diameter through hole land 1 and changing the value of the capacitance C1. it can.

As described above, in this embodiment, a single substrate 6 is formed by laminating double-sided substrates on which patterns such as the signal wiring pattern 4, the large-diameter through-hole land 1 and the inner ground layer 5 are formed. And a signal line through is formed on a single substrate 6.
After forming the hole 6a for forming the hole 3, the hole 6a
Is plated to form a signal line through hole 2 and a signal line through hole 3, and a signal line through hole 3 is formed.
Since the signal wiring pattern 4 and the large-diameter through-hole land 1 are connected to the hole 3, the manufacturing process can be simplified.

In the present embodiment, the facing region 8 between the large-diameter through-hole land 1 and a part of the ground inner layer 5 has a capacity, and the capacity is changed to the large-diameter through-hole.
Since the inductance of the connector 7 is canceled by increasing or decreasing the diameter or the area of the land 1 and the equivalent impedance and the characteristic impedance of the substrate 6 are matched, the impedance accompanying the inductance of the connector 7 is adjusted. Dance matching can be easily achieved.

As a result, in the transmission of a high-frequency signal, a printed wiring board is obtained in which the waveform distortion caused by the inductance of the connector 7 is eliminated.

In this embodiment, the case of a printed wiring board mounted on both sides has been described. However, when the connector 7 is surface-mounted on the board 6, a dummy signal through-hole is mounted on the board 6. To form this damyl sulfo-
A large-diameter through-hole land 1 may be formed for the shell.

The large-diameter through-hole land 1 is not limited to a circular shape, but may have an arbitrary shape. further,
The large-diameter through-hole land 1 may be disposed facing the inner layer 5 of the ground, and is formed on the outer layer of the substrate 6 to avoid contact with other patterns such as the signal wiring pattern 4. It is also possible.

[0034]

As described above, according to the printed wiring board and the method of manufacturing the same according to the present invention, a double-sided board on which a pattern such as a signal wiring pattern, a large-diameter through-hole land and a ground inner layer is formed is laminated. Then, a single substrate is formed, and a hole for forming a signal line through hole is formed in the single substrate. Then, the holes are plated to form a signal line through hole land and a signal line through hole. By forming a signal wiring pattern and connecting a signal wiring pattern and a large-diameter through-hole land to the signal line through-hole, the manufacturing process is simplified, and the large-diameter through-hole land and the ground are connected. By providing a capacitance between a part of the inner layer and changing the value of the capacitance by increasing or decreasing the diameter or area of the large-diameter through-hole land, the equivalent impedance and characteristic impedance of the substrate are obtained. Since such matching of dance, without increasing the manufacturing cost, the connector of the inductance of the Inpi - can take facilitate dance matching.

[Brief description of the drawings]

FIG. 1 is a diagram showing one embodiment of a printed wiring board of the present invention.

FIG. 2 is a process chart showing a method for manufacturing the printed wiring board of FIG. 1;

FIG. 3 is a diagram showing an equivalent circuit of the printed wiring board of FIG. 1;

FIG. 4 is a process chart for explaining a conventional method for manufacturing a printed wiring board.

FIG. 5 is a cross-sectional view illustrating a state where a connector is described on the printed wiring board of FIG. 4;

6 is a diagram showing an equivalent circuit of the printed wiring board of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Large-diameter through hole land 2 Signal line through hole land 3 Signal line through hole 4 Signal wiring pattern 5 Ground inner layer 6 Substrate 6a, 6b, 6c hole 7 Connector 8 Opposing area 10 Driver circuit 11 Receiver circuit 12 Insulator

Claims (4)

(57) [Claims] 1. A printed wiring board comprising: a signal line through hole formed on a board to which a connector is connected; and a signal wiring pattern connected to the signal line through hole land. A large-diameter through-hole land formed on an inner layer or an outer layer of the substrate is connected, and a ground inner layer not connected to the signal line through-hole is provided at a position facing the large-diameter through-hole land.
Wherein the substrate is provided with the large-diameter through-hole land and signal wiring.
Both the pattern and the pattern such as the inner layer of the ground are formed.
A ground inner layer which is formed by laminating surface substrates and faces the large-diameter through-hole land.
Depending on the change in the capacitance provided in the facing area between
Wherein the equivalent impedance of the substrate can be changed . 2. The printed wiring board according to claim 1 , wherein the value of the capacitance is changed by increasing or decreasing the diameter or the area of the large-diameter through-hole land. 3. A method for manufacturing a printed wiring board, wherein a signal wiring pattern is connected via a signal line through hole land to a signal line through hole formed on a substrate to which a connector is connected, wherein the signal wiring pattern is provided. A first step of laminating a double-sided board on which patterns such as a large-diameter through-hole land and a ground inner layer are formed to form a single board; and forming the signal line through-hole in the single board. A second step of forming a hole, and plating the hole to form the signal line through hole land and the signal line through hole, and the signal wiring pattern and the large diameter through hole in the signal line through hole. The third process to connect the land ground
So that a part thereof faces the large-diameter through-hole land.
Forming the inner layer of the ground, the large diameter through hole land
And a fourth capacitor having a capacitance between the ground and a part of the ground inner layer.
Method for manufacturing a printed wiring board, characterized in that it comprises a step. 4. The method according to claim 4, wherein the value of the capacitance is
4. The method according to claim 3 , further comprising a step of changing the diameter or area of the large-diameter through-hole land.