JP2000223799A - Wiring board and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wiring board in which a route used for the flow of a feedback current is ensured, in which the disorder of an electric field or a magnetic field is reduced and in which the radiation level of unwanted radio waves is reduced. SOLUTION: When a signal interconnection 5 is formed so as to cross a grounding conductor pattern 7, a parallel grounding line 10 is formed in such a way that it is parallel to the signal interconnection 5 and that it connects grounding patterns 6 formed on both end sides of the crossed grounding conductor pattern 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wiring board on which a semiconductor integrated circuit such as an LSI, a connector, a chip component or the like is mounted and which is incorporated in an electronic device or apparatus, and a method of manufacturing the same.

[0002]

2. Description of the Related Art As such a wiring board, for example, a strip line or a microstrip line is frequently used, and FIG. 7 is a configuration diagram showing an example of such a wiring board. For example, two LSI packages 2 and 3 are mounted on the wiring board 1. These LSI packages 2 and 3 have a plurality of leads 2 a and 3 a, respectively, and are connected to a plurality of electrode pads 4 formed on the wiring board 1. And these LSI packages 2, 3
Is connected between predetermined leads 2a and 3a by a signal wiring 5 such as a strip line or a microstrip line.

On the other hand, in such a wiring board 1, a plurality of levels of power supply voltages are mixed, for example, 5V for an external I / F (interface) of an LSI, 3.3V for an LSI core logic, and a small-amplitude high-speed I / F. For example, there is 1.0V. In response to this, the ground level is not limited to the voltage level of 0 V, but may be, for example, a voltage level of 1.5 to 0.5.
In the range of V, ground levels of a plurality of voltage levels are mixed.

On the wiring board 1 shown in FIG. 7, a plurality of ground conductor patterns 6, 7 are formed insulated from each other via a ground slit 8, and the ground conductor patterns 6, 7 are grounded. The levels are different. Therefore, each of the above LSIs
The signal wiring 5 connecting the packages 2 and 3 is wired across one grounding conductor pattern 7.

When a signal, that is, a current flows through the signal wiring 5, an induced current (feedback current) flowing in a direction (b) opposite to the direction (b) of the current flow as shown in FIG. It is guided to the ground conductor pattern facing the wiring 5. The higher the frequency of the signal, that is, the current in the signal wire 5, the more the return current is concentrated and localized in a portion directly below or directly above the signal wire 5.

[0006]

However, as shown in FIG. 7, the signal wiring 5 is connected to the conductor pattern 7 for ground.
, The feedback current flows through a large bypass path i as shown in FIG.

As a result, the electric field and the magnetic field are greatly disturbed by the detouring feedback current, and the electromagnetic field energy confined in the space between the signal wiring 5 and the ground conductor pattern 7 is released to the outside. There is a problem that the amount of emission of unnecessary radio wave (EMI) increases.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a wiring board and a method for manufacturing the same, which can secure a path for a return current to reduce disturbance of an electric field and a magnetic field and reduce an unnecessary radio wave radiation level.

[0009]

According to the present invention, there is provided a wiring board having at least one signal wiring layer having signal wiring and at least one power supply ground layer having a plurality of insulated ground conductor patterns. When laying the signal wiring over the ground conductor pattern, at least one parallel ground connecting the ground conductor patterns formed in parallel with the signal wiring and on both ends of the ground conductor pattern straddled. This is a wiring board for forming lines.

According to the second aspect, in the wiring board according to the first aspect, the parallel ground line allows an induced current to flow in a direction opposite to a current flowing in the signal wiring.

According to the third aspect, in the wiring board according to the first aspect, parallel ground lines are formed at a predetermined ratio to a plurality of signal wirings.

According to the fourth aspect, in the wiring board according to the first aspect, the parallel ground line is formed in a flat plate shape.

According to a fifth aspect of the present invention, in the wiring board according to the first aspect, the parallel ground line is formed on the signal wiring layer on which the signal wiring is formed.

According to the sixth aspect of the present invention, in the wiring board according to the first aspect, the parallel ground line is formed on another layer sandwiching the signal wiring from the power supply ground layer on which the ground conductor pattern is formed.

According to a seventh aspect of the present invention, there is provided a method of manufacturing a wiring board having at least one signal wiring layer having signal wiring and at least one power ground layer having a plurality of insulated ground conductor patterns. And connecting at least one parallel ground line parallel to the signal wiring and connecting between the ground conductor patterns formed on both ends of the straddled ground conductor pattern. Forming a wiring board.

[0016]

(1) Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. The same parts as those in FIG. 7 are denoted by the same reference numerals.

FIG. 1 is a plan view showing the structure of the wiring board, and FIG.
FIG. 3A is a cross-sectional configuration diagram, and FIG. 3A is a diagram illustrating a state in which a signal wiring 5 is wired across a ground slit 8.
FIG. 2B is a view showing a state where the parallel ground line 10, which is a key point of the present invention, is wired across the ground slit 8.

The wiring board 1 is a printed board or a build-up board, which is incorporated in an electronic device or apparatus.

The wiring substrate 1 is a ceramic substrate made of aluminum oxide, aluminum nitride, silicon nitride, or the like, and is incorporated in an electronic device or device.

The wiring substrate 1 is manufactured by a thin film process using polyimide or the like, and is incorporated in an electronic device or apparatus.

The structure of the wiring board 1 will be described in detail. The wiring board 1 has an insulating layer 11 and a signal formed on the insulating layer 11 as shown in FIGS. It is composed of a wiring layer 12 and a power ground layer 13 formed below the insulating layer 11.

A plurality of ground conductor patterns 6 and 7 are formed in the power supply ground layer 13 so as to be insulated from each other via a ground slit 8. The ground levels of the ground conductor patterns 6 and 7 are as follows. Type of power supply voltage, for example, 5 V for external I / F of LSI, LSI
3.3V for core logic and 1.0V for small-amplitude high-speed I / F.
The voltage levels are not limited to the above, and are a plurality of voltage levels within a voltage level range of 1.5 to 0.5V, for example.

In the signal wiring layer 12, a plurality of electrode pads 4 are formed at predetermined portions, and, for example, two LSI packages 2, 3 are mounted on the electrode pads 4. In these LSI packages 2 and 3, predetermined leads 2a and 3a are connected across the ground slit 8 by a signal wiring 5 such as the strip line or the microstrip line.

The parallel ground line 10 is connected to the signal line 5 in parallel. That is, through holes 14 and 15 are formed near the respective LSI packages 2 and 3 in the ground conductor pattern 6 and on the edge side along the signal wiring 5. These through holes 1
As shown in FIG. 2 (b), the wires 4 and 15 pass through the insulating layer 11 from the signal wiring layer 12 to the power ground layer 13 and are connected to the ground conductor pattern 6, respectively. The parallel ground line 10 is connected to the through holes 14 and 15 as shown in the enlarged perspective view of FIG. 3, and is wired in parallel with the signal wiring 5 and straddling the ground slit 8.

In the case of manufacturing such a wiring board 1, for example, a step of arranging the signal wiring 5 over the ground conductor pattern 7 and a step of arranging the ground conductor pattern 7 in parallel with the signal wiring 5. Ground lines 1 connecting between the ground conductor patterns 6 formed on both ends of the
0 is formed.

Next, the operation of the wiring board configured as described above will be described.

When a signal, ie, a current S, flows between the LSI packages 2 and 3 through the signal wiring 5, a feedback current K flowing in a direction opposite to the direction in which the current S flows as shown in FIG.
Flows through the ground conductor pattern 6 directly below the signal wiring 5 and flows from the through holes 14 and 15 through the parallel ground line 10. This feedback current K is applied to the signal line 5
As the frequency of a signal propagating through the signal line becomes higher, the signal is concentrated and localized at a portion directly below the signal wiring 5 and flows to the parallel ground line 10.

As described above, since the feedback current K flows through the parallel ground line 10 parallel to the signal wiring 5, even if the signal wiring 5 is wired across the ground slit 8, it does not flow through a large detour path. Absent. Accordingly, the relationship between the current S flowing through the signal wiring 5 and the feedback current K is maintained even in a portion straddling the ground slit 8, disturbance of an electric field and a magnetic field can be minimized, and unnecessary radio wave emission (EM
The amount of release of I) can be minimized.

As described above, in the first embodiment, when the signal wiring 5 is laid across the ground conductor pattern 7, the wiring of the ground conductor pattern 7 parallel to and astride the signal wiring 5 is performed. Since the parallel ground lines 10 are formed so as to connect the ground conductor patterns 6 formed on both ends, the relationship between the current S flowing through the signal wiring 5 and the feedback current K can be maintained, and the electric field and the magnetic field can be maintained. Disturbance can be minimized, and the amount of unnecessary radio wave emission (EMI) can be minimized. (2) Next, a second embodiment of the present invention will be described with reference to the drawings.

FIG. 4 is a plan view showing the structure of the wiring board.

The wiring board 20 is a printed board or a build-up board, which is incorporated in an electronic device or apparatus. The wiring substrate 20 is a ceramic substrate made of aluminum oxide, aluminum nitride, silicon nitride, or the like, and is incorporated in an electronic device or device. The wiring substrate 20 is manufactured by a thin film process using polyimide or the like, and is incorporated in an electronic device or device.

The structure of the wiring board 20 will be described in detail. A ground conductor pattern 21 and a power supply conductor pattern 22 are formed below the wiring board 20. Among them, the ground conductor pattern 21 has a voltage level of 0 V, and the power supply conductor pattern 22 has, for example, a voltage level of 1.5 to 0 .0 corresponding to an LSI external I / F, an LSI core logic, and a small-amplitude high-speed I / F. The voltage level is in the range of 5V. A ground slit 23 is formed between the ground conductor pattern 21 and the power supply conductor pattern 22.

On the other hand, a plurality of electrode pads 24 are formed at predetermined portions on the upper layer side of the wiring board 20, and, for example, two LSI packages 2 are formed on these electrode pads 24.
5 and 26 are connected and mounted.

The LSI packages 25, 2
Reference numeral 6 designates a plurality of, for example, nine signal wires 29 such as the strip lines and microstrip lines, which are wired above the power supply conductor pattern 22 and connected between predetermined leads 27 and 28.

In addition, three parallel ground lines 30 are wired in parallel with these nine signal lines 29. That is, through holes 31 and 32 are formed in the ground conductor pattern 21 near the respective LSI packages 25 and 26 and on the edge side along the respective signal wires 29. These through holes 31 and 32 penetrate from the upper layer side to the lower layer side, respectively, and are connected to the ground conductor pattern 21 on the lower layer side. The three parallel ground lines 30 are connected to the respective through holes 31 and 32, and are wired in parallel with the signal wiring 29 and straddling the power supply conductor pattern 22.

Next, the operation of the wiring board configured as described above will be described.

When a signal flows between the LSI packages 25 and 26 through the nine signal lines 29, a feedback current flowing in a direction opposite to the direction in which the current flows flows through the ground conductor pattern 21 immediately below each signal line 29. At the same time, it flows from each through hole 31, 32 through three parallel ground lines 30.

Since this feedback current flows in the parallel ground line 30 parallel to each signal wiring 29, even if each signal wiring 29 is wired across the ground slit 23, it does not flow through a large detour path. . As a result, the relationship between the current flowing through each signal wiring 29 and its return current is maintained even in a portion straddling the ground slit 23, disturbance of the electric field and magnetic field can be minimized, and unnecessary radio wave radiation (EMI ) Can be minimized.

As described above, according to the second embodiment, similar to the first embodiment, when each signal wiring 29 is laid across the power supply conductor pattern 22 from the ground slit 23, Since three parallel ground lines 30 were formed so as to connect between the ground conductor patterns 21 formed at both ends of the power supply conductor pattern 22 in parallel with and straddling the nine signal wires 29, each of the three parallel ground lines 30 was formed. The relationship between the current flowing through the signal wiring 29 and the feedback current can be maintained, the disturbance of the electric field and the magnetic field can be minimized, and the emission amount of unnecessary radio wave radiation can be minimized.

Although it is best to wire the parallel ground line 30 at a ratio of one signal wire 29 to one signal wire 29 in order to minimize the amount of emission of unnecessary radio wave radiation, As described in the embodiment, three signal wirings 29 of three parallel ground lines 30
The same effect as that of the first embodiment can be obtained even if wiring is performed at a ratio of two parallel ground lines 30 or at a ratio of one parallel ground line 30 to two signal wires 29. be able to. (3) Next, a third embodiment of the present invention will be described with reference to the drawings.

FIG. 5 is a perspective view showing the layer structure of the wiring board.

The wiring board 40 has a structure in which a space for forming the parallel ground lines 52 and 53 in parallel with the signal wiring layer 42 cannot be secured, and the signal wiring layer 42 is formed above the ground layer 41. Other layers 4 on top of it
A plurality of layers such as three are formed. Ground layer 4
1, each ground conductor pattern 45, 46 is formed via a ground slit 44.

Each signal wiring layer 42 has an L (not shown).
A signal wiring 47 connecting between the SI packages is formed. This signal wiring 47 is wired across the ground slits 44 between the ground conductor patterns 45 and 46.

Further, from each of the ground conductor patterns 45 and 46 of the ground layer 41 through the signal wiring layer 42 to the other layer 4
For example, four through holes 48 to 51 are provided between the three.

In these through holes 48 to 51, the through holes 48 and 49 are connected by a parallel ground line 52 in another layer 43, and the other through holes 50 and
51 are connected by a parallel ground line 53.

The parallel ground lines 52 and 53 are formed in parallel with the signal wiring 47 and straddling the ground slit 44.

Next, the operation of the wiring board configured as described above will be described.

When a signal flows between the respective LSI packages through the signal wiring 47, a feedback current flowing in a direction opposite to the flowing direction of the current flows to the ground conductor patterns 45 and 46 immediately below the signal wiring 47, and these ground conductors also flow. The current flows from the patterns 45 and 46 to the parallel ground lines 52 and 53 through the through holes 48 to 51.

Since this feedback current flows through the parallel ground lines 52 and 53 parallel to the signal wiring 47,
Does not flow through a large detour path even if it is wired across the ground slit 44. This allows
The relationship between the current flowing through the signal wiring 47 and its return current is maintained even in the portion over the ground slit 44, the disturbance of the electric field and the magnetic field can be minimized, and the emission amount of unnecessary radio wave radiation is minimized. Can be suppressed.

As described above, according to the third embodiment, the parallel ground lines 52 and 53 extend in parallel with the signal wiring layer 42.
Even if the structure cannot secure a space for forming the through holes 48 to 46 through the signal wiring layer 42 and the other layers 43 from the ground conductor patterns 45 and 46, respectively.
A parallel ground line 52 is connected between the through holes 48 and 49, and the other through holes 5 are provided.
A parallel ground line 53 is connected between 0 and 51, and the parallel ground lines 52 and 53 are formed in parallel with the signal wiring 47 and across the ground slit 44, so that the current flowing through the signal wiring 47 and the feedback The relationship with the current can be maintained, the disturbance of the electric and magnetic fields can be minimized, and the amount of emission of unnecessary radio wave radiation can be minimized.

The present invention is not limited to the first to third embodiments, but may be modified as follows.

For example, the same effect can be obtained even if the parallel ground line is not formed in a line shape but is formed in a plane shape.

As shown in FIG. 6, the LSI packages 62 and 63 are mounted on a wiring board 61 in which an opening 60 is formed. Even in the case where wiring is performed over the signal wiring 64, the parallel ground line 65 is formed in parallel with the signal wiring 64 and over the opening 60, so that the current between the current flowing through the signal wiring 64 and the feedback current is formed in the same manner as described above. , The disturbance of the electric field and the magnetic field can be minimized, and the emission amount of unnecessary radio wave radiation can be minimized.

The LSI package format is DIP,
Similar effects can be obtained even when packages of any type of QFP, TAB, and BGA or a plurality of types of packages are mixed.

[0055]

As described above in detail, according to the present invention, there is provided a wiring board and a method of manufacturing the wiring board which can secure a path for a return current to reduce disturbance of an electric field and a magnetic field and reduce an unnecessary radio wave radiation level. it can.

[Brief description of the drawings]

FIG. 1 is a plan view showing a first embodiment of a wiring board according to the present invention.

FIG. 2 is a sectional configuration diagram of the wiring board.

FIG. 3 is an enlarged perspective view of a main part of the wiring board.

FIG. 4 is a plan view showing a second embodiment of the wiring board according to the present invention;

FIG. 5 is an enlarged perspective view of a main part showing a third embodiment of the wiring board according to the present invention.

FIG. 6 is a plan view showing a modification of the present invention.

FIG. 7 is a configuration diagram showing an example of a conventional wiring board.

FIG. 8 is a schematic diagram showing a path of a feedback current.

[Explanation of symbols]

 1: wiring board, 2, 3: LSI package, 2a, 3a: lead, 4: electrode pad, 5: signal wiring, 6, 7: conductor pattern for ground, 8: ground slit, 10: parallel ground line, 11: Insulation layer, 12: signal wiring layer, 13: power supply ground layer, 14, 15: through hole, 20: wiring board, 21: ground conductor pattern, 22: power supply conductor pattern, 23: ground slit, 25, 26: LSI package, 29: signal wiring, 30: parallel ground line, 31, 32: through hole, 40: wiring board, 41: ground layer, 42: signal wiring layer, 43: other layer, 44: ground slit, 45, 46: conductor pattern for ground, 47: signal wiring, 48 to 51: through hole, 52, 53: parallel ground line.

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference)

Claims (7)

[Claims] 1. A wiring board having at least one signal wiring layer having signal wiring and at least one power supply ground layer having a plurality of insulated ground conductor patterns, wherein the signal wiring is formed of the ground conductor pattern. In the case of straddling, at least one parallel ground line is formed to connect between the ground conductor patterns formed on both ends of the ground conductor pattern in parallel with the signal wiring. Wiring board. 2. The wiring board according to claim 1, wherein the parallel ground line is configured to flow an induced current flowing in a direction opposite to a current flowing through the signal wiring. 3. The wiring board according to claim 1, wherein said parallel ground lines are formed in a predetermined ratio to a plurality of said signal lines. 4. The wiring board according to claim 1, wherein the parallel ground line is formed in a flat plate shape. 5. The wiring board according to claim 1, wherein the parallel ground line is formed on the signal wiring layer on which the signal wiring is formed. 6. The wiring board according to claim 1, wherein the parallel ground line is formed on another layer sandwiching the signal wiring from the power ground layer on which the ground conductor pattern is formed. . 7. A method of manufacturing a wiring board in which at least one signal wiring layer having signal wiring and at least one power supply ground layer having a plurality of insulated ground conductor patterns are formed. Laying over a conductor pattern, and forming at least one parallel ground line connecting between the ground conductor patterns formed on both ends of the ground conductor pattern in parallel with and over the signal wiring. A method for manufacturing a wiring board, comprising: