JPH11330711A - Multilayer board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To build a circuit having electrically fewer troubles, even in the case of high density wirings by providing an insulating board of a high permittivity material between a plurality of power source boards, and using an insulating board of a low permittivity for an insulating part with a signal board. SOLUTION: Conductor boards 25, 28, disposed on both side surfaces of the multilayer board, are signal boards to be mounted by soldering electronic components with creamy solder, DIP layer or the like. Conductor boards 26, 27 disposed at an intermediate are mainly power boards to become a supply pattern and a ground line of a power source voltage. A variety of through-holes 29a to 29c are properly provided via a wiring pattern of upper and lower boards. As an insulating board sandwiched between the boards 26 and 27, an insulating material having extremely high permittivity is adopted, and a relatively low dielectric material is used for insulating boards 21, 23 adjacent to the signal boards 25, 28 of both side surfaces. An impedance of the conductor boards disposed via the insulating board can be handled as a distributed constant circuit with respect to high frequency.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer board on which many electronic devices are mounted at high density, and more particularly to a multilayer board in which a power supply board and a signal board are stacked in a multilayer structure.

[0002]

2. Description of the Related Art As a printed wiring board, a conductor substrate is arranged only on one surface of a substrate material, a single-sided substrate on which a wiring circuit is patterned on the conductor substrate, and a conductor substrate is arranged on both surfaces of an insulating substrate. 2. Description of the Related Art A double-sided board on which a large number of electronic components are mounted while connecting the boards to each other by through holes or the like is often used.

However, in the case of a computer device or a small electronic device, an electronic circuit for processing a larger amount of information than the size of the electronic device is required.
In such a case, since it is necessary to form a large number of electronic components and a complicated wiring pattern in a narrow space, a multilayer substrate having a multilayered conductor substrate has been put to practical use.

For example, FIG. 3 is a plan view of a six-layer multilayer substrate,
The cross section (AB) is shown, and 11, 12,
Reference numerals 13, 14, and 15 denote multilayer insulating substrates that insulate the conductor plates, and the internal wiring substrate is sandwiched between the insulating substrates 11 to 15. Reference numerals 16 and 16 denote solder lands of electronic components mounted on the surface. In the case of electronic components with lead terminals, they may be soldered through the through holes 17. In some cases, a penetrating via hole 18 for simply penetrating both surfaces may be provided, or an interstitial via hole 19 in which a hole is formed up to an intermediate substrate.

[0005]

By the way, in general, in the case of high-density electronic equipment, the wiring pattern thereof is complicated and often handles high-frequency signals. It can be a problem. In general, the power supply impedance is set to an extremely low value. However, when the power supply line moves back and forth between a relatively large number of wiring patterns, a function as a ground point for a signal cannot be expected. State, and the operation of the circuit becomes unstable.

[0006]

SUMMARY OF THE INVENTION The present invention provides a multi-layer substrate capable of reducing such problems.
In a multilayer board including at least one or two power supply boards and a signal board on which two or more wiring patterns are formed, the insulation between the power supply boards is made of a material having a high dielectric constant as an insulating board. The insulating portion uses an insulating substrate having a low dielectric constant.

[0007] In particular, in the case of the present invention, the power supply board is arranged in the middle portion of the multilayer board and the signal board is arranged on the front side, so that the low dielectric constant insulating substrate and the high dielectric constant insulating substrate can be used properly. As a result, the deterioration of the signal transmitted through the high-frequency circuit is minimized by using a low-frequency loss type material.

[0008] Since the dielectric constant of the insulating substrate constituting the multilayer substrate is appropriately selected according to the electric signals entering and exiting the conductor substrates located on both surfaces thereof, a low power supply impedance is provided when the multilayer substrate is formed. At the same time, the influence of the transmission speed on the signal lines is reduced to stabilize the circuit.

[0009]

FIG. 1 shows an embodiment of the present invention.
The multi-layer substrate is shown in a perspective view, part of which is shown in cross section. In this figure, 21, 22, and 23 are insulating substrates,
Reference numeral 24 denotes a real-phase electronic component, and reference numerals 25, 26, 27, and 28 denote conductor substrate portions. The conductor boards 25 and 28 located on both sides of the multilayer board are particularly called signal boards because the electronic components are soldered and mounted with cream solder, a dip layer or the like. 26,
27 is mainly referred to as a power supply board because it mainly serves as a power supply voltage supply pattern and a ground line. Note that 29
(A, b, c) shows various through holes provided as appropriate according to the wiring patterns of the upper and lower substrates.

In the case of the multilayer board of the present invention, an insulating material having an extremely high dielectric constant is adopted as the insulating board 22 sandwiched between the power supply boards 26 and 27, and is adjacent to the signal boards 25 and 28 on both sides. Insulating substrate 21,
23 is characterized in that a relatively low dielectric material is used.

In general, the impedance of a conductor substrate disposed with an insulating substrate interposed therebetween can be handled as a distributed constant circuit in terms of high frequency, and its characteristic is that an inductance component per unit length is reduced as shown in FIG. It can be regarded as a transmission line having L and a capacitance component of C. The propagation speed v of a signal transferred on such a transmission line is represented by v = 1 / LC, and the wave impedance is Z = (L / C).

In the multilayer board of the present invention, the signal boards 25, 28
The distribution capacitance C per unit length is reduced by configuring the insulating substrates 21 and 23 that are adjacent to each other to have a low dielectric constant. Therefore, the smaller the distribution capacitance C per unit length, the higher the transfer speed V with the same wiring pattern, and the more stable the operation of the circuit.

In the case of the multilayer substrate of the present invention, the dielectric constant ε of the insulating substrate 22 tightly attached to the power supply substrates 26 and 27 is set to be as high as possible. Also in this case, as is well known, when the dielectric constant increases, the capacitive impedance C per unit length increases, and an effect of lowering the internal impedance of the power supply substrate can be provided.

As an insulating material for setting a low dielectric constant,
For example, tetrafluorocarbon (trade name: Teflon) can be considered, and in the case of this material, the high frequency loss is relatively small, so that it is extremely effective as a multilayer substrate. As a material having a relatively high dielectric constant, for example, epoxy in which ceramic is dispersed can be used. In this case, even if the high-frequency loss is large to some extent, it is preferable that there is no thermal deformation and strength is high.

In the above embodiment, a four-layer board has been described. However, it is needless to say that the present invention can be applied to a multi-layer board having four or more layers. In this case, a power supply board is disposed at an intermediate portion so as to face through an insulating substrate, and the insulating board is made of a material having a high dielectric constant, and a signal board to be stacked on the power supply line is stacked on the outside thereof. It is preferable to use an insulating substrate having a low dielectric constant as these insulating substrates.

[0016]

As described above, in the case of the multilayer substrate of the present invention, the insulating substrate having a high dielectric constant and the insulating substrate having a low dielectric constant are provided by an electric signal or a power supply supplied to the multilayered conductive substrate. Since an appropriate combination of insulating substrates is used, there is an advantage that a circuit with little electrical trouble can be constructed even when wiring is performed at high density.

[Brief description of the drawings]

FIG. 1 is a perspective view of a multilayer substrate showing one embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a dielectric constant, a transmission speed, and an impedance of an insulating substrate constituting a multilayer substrate.

FIG. 3 is an explanatory diagram of a conventional multilayer substrate.

[Explanation of symbols]

 21, 22, 23 Insulating board 24, 28 Signal board 25, 26 Power board

Claims (4)

[Claims] 1. A multilayer board including at least one or two power supply boards and a signal board on which two or more wiring patterns are formed, wherein insulation between the power supply boards is made of a material having a high dielectric constant, A multilayer substrate, wherein an insulating substrate having a low dielectric constant is used for an insulating portion between the substrate and the signal substrate. 2. The multi-layer substrate according to claim 1, wherein the insulating substrate having a low dielectric constant is made of a low-loss type material. 3. The multilayer substrate according to claim 2, wherein said insulating substrate is made of glass / epoxy resin. 4. The multi-layer board according to claim 1, wherein the power board is arranged at an intermediate portion of the multi-layer board, and the signal board is arranged on the front side with respect to the power board.