JP2002151854A - Multilayer printed wiring board and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the dielectric constant of an adhesive insulation board inserted between printed wiring boards, thereby promoting high-speed processing signals to flow on conductive foils which are to be signal wirings provided on the printed wiring boards. SOLUTION: The multilayer printed wiring board is formed by heating and pressing laminated printed wiring boards 12, having conductive foils 11 for forming wirings in a multiple layer on at least one surface of an insulation board 10 via adhesive insulation boards 13, having an adhesive function. Hollow parts 13a are provided in a part of the adhesive insulation board 13; hollow parts 13a are provided in corresponding portions of the adhesive insulation board 13 to the peripheries of the conductive foils 11 to be signal wirings provided on the printed wiring boards 12; or if conductive foils 11 to be signal wirings are provided on the printed wiring board 12 at high density, hollow parts 13a are provided at random in the adhesive insulation board 13, thus forming a multilayer printed wiring board 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer printed wiring board used for a configuration of an electronic circuit of an electronic device and a place for connecting the electronic circuits to each other.

[0002]

2. Description of the Related Art As shown in FIG. 8, a conventional multi-layer printed wiring board has a conductive foil 2 on one or both sides of an insulating substrate 1 serving as each wiring section such as signal wiring, power supply wiring, and ground conductive section.
The printed wiring board 3 having the above structure is laminated in multiple layers via an adhesive insulating substrate (referred to as a prepreg) 4 having an adhesive function by heating and pressing, and this is heated and pressed to form a multilayer printed wiring board 5. .

[0003]

In recent years, in electronic equipment, high-speed transmission of electric signals between electronic components can be realized.
In addition, a multilayer printed wiring board with a high mounting density of electronic components is required, and the multilayer printed wiring board is becoming thinner and smaller, which results in higher performance of the multilayer printed wiring board and higher signal wiring density. Multilayer printed wiring boards have been developed.

In a multilayer printed wiring board as in the conventional example, in order to cope with a high-speed transmission of an electric signal,
The insulating substrate 1 and the adhesive insulating substrate 4 that form the printed wiring board 3 have a dielectric constant εr of 3.5 to 4.8 and have a low dielectric constant. It is common to make it correspond.

For example, the signal wiring width is 0.2 mm, the signal wiring thickness is 0.04 mm, and the thickness of the insulating substrate 1 is 0.12 mm.
7 mm, and the characteristic impedance Z0 between the conductive foil 2 serving as the signal wiring and the conductive foil 2 serving as the ground conductive portion is 50Ω.
By doing so, a multilayer printed wiring board that supports high frequencies of electric signals is formed.

In recent years, in the processing of mixed signals of digital signals and analog signals, signals from artificial satellites, and signals from computers and the like, high-speed processing of signals has been attempted. Further, the frequency characteristics of electric signals of electronic components mounted on a printed wiring board have been improved.

In a conventional multilayer printed wiring board formed by alternately laminating a printed wiring board and an adhesive insulating substrate having an adhesive function by heating and pressing, the dielectric constant of the adhesive insulating substrate is higher than that of air. Due to the large capacitance, the capacitance between the signal wirings of the printed wiring boards laminated with the adhesive insulating substrate therebetween, between the signal wiring and the power supply wiring, or between the signal wiring and the ground conductive part also increases. However, the signal flowing through the signal wiring is delayed, so that it is not possible to cope with high-speed processing of the signal and improvement of the frequency characteristic of the signal. An object of the present invention is to provide a multilayer printed wiring board and a method for manufacturing a multilayer printed wiring board that eliminate such problems.

[0008]

According to the first aspect of the present invention, a printed wiring board having a conductive foil on each of at least one surface of an insulating substrate is heated and pressed. A multilayer printed wiring board having a hollow portion 13a provided in a part of the adhesive insulating substrate 13, the multilayer printed wiring board being laminated in multiple layers via an adhesive insulating substrate 13 having an adhesive function. It is.

According to a second aspect of the present invention, a hollow portion 13a is provided in a portion of the adhesive insulating substrate 13 corresponding to a periphery of a conductive foil 11 'serving as a signal wiring portion provided on the printed wiring board 12. A multilayer printed wiring board 14 according to claim 1.

The invention according to claim 3 is characterized in that, when the printed wiring board 12 is provided with a conductive foil 11 'which becomes a signal wiring portion by increasing the density, the adhesive insulating substrate 1 is provided.
3. The multilayer printed wiring board 14 according to claim 1, wherein the hollow portions 13a are provided randomly.

According to a fourth aspect of the present invention, the outermost printed wiring board of the plurality of stacked printed wiring boards is a flexible printed wiring board 12 '. In the multilayer printed wiring board.

According to a fifth aspect of the present invention, the insulating substrate 1
A printed wiring board 12 having a conductive foil 11 serving as each wiring portion on at least one surface of the printed wiring board 0 and an adhesive insulating substrate 13 having a hollow portion 13a having a bonding function by heating and pressing are prepared. Adhesive insulating substrates 13 are alternately laminated and heated and pressed to form a multilayer printed wiring board 14.
And a method for manufacturing a multilayer printed wiring board.

According to a sixth aspect of the present invention, there is provided the insulating substrate
A printed wiring board 12 having a conductive foil 11 to be each wiring portion on at least one surface of the printed wiring board 12;
A portion corresponding to the periphery of the conductive foil 11 ′ serving as a signal wiring portion provided in the above becomes a hollow portion 13 a to prepare an adhesive insulating substrate 13 having an adhesive function by heating and pressing, and the printed wiring substrate 12 and the adhesive insulating substrate 13 are formed. Are alternately laminated and heated and pressed to manufacture the multilayer printed wiring board 14, which is a method for manufacturing a multilayer printed wiring board.

According to a seventh aspect of the present invention, there is provided the insulating substrate
The printed wiring board 12 has an adhesive insulating substrate piece 13 ′ having an adhesive function by heating and pressing on a conductive foil 11 having at least one surface of a printed wiring board 11, and a hollow portion 13 a in a portion where an outer peripheral portion 13 b is left. An adhesive insulating substrate 13 having an adhesive function by heating and pressing on a portion including an adhesive insulating substrate 13 having an adhesive function by heating and pressing and a conductive foil 11 ′ serving as a high-density signal wiring on at least one surface of the insulating substrate 10. A printed wiring board 12 on which a substrate piece 13 ′ is mounted, an adhesive insulating substrate 13 having a hollow portion 13 a in a portion where an outer peripheral portion 13 b is left, and a conductive foil 11 on at least one surface of the insulating substrate 10.
And the printed wiring board 12 having a hollow portion 13a are randomly laminated in the adhesive insulating substrate 13 by heating and pressing.
And a method of manufacturing a multilayer printed wiring board characterized by manufacturing a multilayer printed wiring board 14 provided with the above.

With such a multilayer printed wiring board 14, the dielectric constant .epsilon.r of the hollow portion 13a of the adhesive insulating substrate 13 is small, and the signal wiring of the printed wiring board 12 laminated with the adhesive insulating substrate 13 interposed therebetween. Conductive foil 1
1 ', between the conductive foil 11' serving as a signal wiring and the conductive foil 11 serving as a power supply wiring, or between the conductive foil 11 'serving as a signal wiring and the conductive foil 11 serving as a ground conductive portion. The capacitance is reduced, and the signal flowing through the conductive foil 11 'serving as the signal wiring is delayed, so that the problem that the signal cannot be processed at high speed or the frequency characteristics of the signal cannot be improved cannot be dealt with.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the multilayer printed wiring board according to the present invention will be described below in detail with reference to the drawings.

According to the first aspect of the present invention, as shown in FIG. 1, a conductive foil 11 serving as a signal wiring portion, a power supply wiring portion, and a ground conductive portion is provided on at least one surface (both surfaces in this embodiment) of an insulating substrate 10. Printed wiring board 12 having
In a multilayer printed wiring board laminated in multiple layers via an adhesive insulating substrate (also referred to as a prepreg) 13 having an adhesive function by heating and pressing, a hollow portion 13 a is provided in a part of the adhesive insulating substrate 13. This is a multilayer printed wiring board 14 to be formed. By configuring the multilayer printed wiring board 14 in such a manner, that is, by reducing the dielectric constant of the adhesive insulating substrate, the dielectric constant and the capacitance between the printed wiring boards 12 can be reduced. As in the case where the dielectric constant and the capacitance are large, the signal flowing through the conductive foil serving as the signal wiring of the printed wiring board 12 is delayed, and it is not possible to cope with the high-speed processing of the signal and the improvement of the frequency characteristic. The problem goes away.

As shown in FIG. 2, a portion of the adhesive insulating substrate 13 corresponding to a periphery of a conductive foil 11 'serving as a signal wiring portion provided on the printed wiring board 12, as shown in FIG. The multilayer printed wiring board 14 according to claim 1, wherein a hollow portion 13a is provided in the multi-layer printed wiring board. In the first and second aspects of the present invention, if the hollow portion 13a formed in the adhesive insulating substrate 13 is wide and a problem in strength occurs, the hollow portion 1a
A bridge (not shown) of the adhesive insulating substrate is formed in any part of 3a. As described above, by providing the hollow portion 13a in the portion of the adhesive insulating substrate 13 corresponding to the periphery of the conductive foil 11 'serving as the signal wiring portion of the printed wiring board 12, the conductive foil 11' serving as the signal wiring portion is provided. The dielectric constant between the opposing conductive foil 11 ′, the conductive foil serving as the power supply wiring, and the conductive foil serving as the ground conductive portion can be reduced (that is, the capacitance is reduced). As in the case where the capacitance is large, the signal flowing through the conductive foil serving as the signal wiring of the printed wiring board 12 is delayed, and it is not possible to cope with high-speed processing of the signal and improvement of the frequency characteristic of the signal.
Such a problem is eliminated.

According to a third aspect of the present invention, as shown in FIG. 3, when the printed wiring board 12 is provided with a conductive foil 11 'serving as a high-density signal wiring portion,
The multilayer printed wiring board according to claim 1, wherein hollow portions (13a) are provided at random on the adhesive insulating substrate (13). With such a configuration, even in a multilayer printed wiring board in which the printed wiring board 12 having the signal wiring portion with a high density is laminated via the adhesive insulating substrate 13, the conductive foil 11 'serving as the signal wiring portion is opposed. The dielectric constant between the conductive foil 11 ′, the conductive foil serving as the power supply wiring, and the conductive foil serving as the ground conductive portion can be reduced, and therefore, as in the case where the dielectric constant and the capacitance are large, the printed wiring can be reduced. The problem that the signal flowing through the conductive foil serving as the signal wiring of the substrate 12 is delayed, and it is impossible to cope with high-speed processing of the signal and improvement of the frequency characteristic of the signal is eliminated.

According to a fourth aspect of the present invention, as shown in FIG. 4, the outermost printed wiring board among the plurality of stacked printed wiring boards is a flexible printed wiring board 12 '. A multilayer printed wiring board according to claim 1, wherein: By laminating such a flexible printed wiring board 12 ', a probe contact (not shown) connected to the printed wiring is provided on the flexible printed wiring board 12', and a contact of an electronic component is provided on the probe contact. Is pressed to test (inspection) the electronic component, the elasticity of the flexible printed circuit board 12 ′
Both contacts can be satisfactorily contacted.

FIG. 5 is a diagram showing a method of manufacturing the multilayer printed wiring board 14 according to the first aspect of the present invention.
A printed wiring board 12 having a conductive foil 11 serving as each wiring portion on at least one surface thereof and an adhesive insulating substrate 13 having a hollow portion 13a having a bonding function by heating and pressing are prepared. Adhesive insulating substrate 13
Are alternately laminated, and heated and pressed to form a multilayer printed wiring board 1.
No. 4 is manufactured.

FIG. 6 is a view showing a method of manufacturing the multilayer printed wiring board 14 according to the second aspect of the present invention. The conductive foil 1 serving as a signal wiring portion is provided on at least one surface of the insulating substrate 10.
1 ', and a portion corresponding to the periphery of a conductive foil 11' serving as a signal wiring portion provided on the printed wiring board 12 becomes a hollow portion 13a, and an adhesive insulating substrate 13 having an adhesive function by heating and pressing. And a method of manufacturing a multilayer printed wiring board, wherein the printed wiring board 12 and the adhesive insulating substrate 13 are alternately laminated, and heated and pressed to manufacture a multilayer printed wiring board 14. It was done.

FIG. 7 is a view showing a method of manufacturing the multilayer printed wiring board 14 according to the third aspect of the present invention. The adhesive has a bonding function on the conductive foil 11 on at least one surface of the insulating substrate 10 by heating and pressing. A printed wiring board 12 having an adhesive insulating substrate piece 13 ′ having a hollow portion 13 a remaining at an outer peripheral portion 13 b and having an adhesive function by heating and pressing; A printed wiring board 12 having an adhesive insulating substrate piece 13 'having an adhesive function by heating and pressing is mounted on a portion including a conductive foil 11' serving as a high-density signal wiring on at least one surface, and an outer peripheral portion 13b. An adhesive insulating substrate 13 having a hollow portion 13a in the remaining portion and a printed wiring board 12 having a conductive foil 11 on at least one surface of the insulating substrate 10 are sequentially laminated, and heated and pressed to form the contact. Hollow 1 randomly in the insulating substrate 13
This is a method for manufacturing a multilayer printed wiring board, characterized in that a multilayer printed wiring board 14 provided with 3a is manufactured. When mounting the adhesive insulating substrate piece 13 'on the printed wiring board 12, the adhesive insulating substrate piece 13' is temporarily fixed on the printed wiring board 12 via an adhesive or the like. .

The conditions of the heating and pressurizing are, for example, in the case of manufacturing a multilayer printed wiring board 14 by alternately laminating printed wiring boards 12 made of glass epoxy resin and bonding and insulating substrates 13 and heating and pressing. After the temperature of the hot platen of the heating and pressurizing device is kept at 130 ° C. ± 5 ° C. for 20 to 30 minutes, the temperature of the hot platen is heated to 170 ° C. In this case, the heating rate is 3
Heat at ° C / min to maintain product temperature at 160 ° C or higher.

The heating and pressing conditions are as follows:
After 25 minutes at MPa, pressure is applied at 2.5 MPa. Next,
After heating and pressurizing at 175 ° C. and 2.5 MPa for 50 minutes or more, the heating is stopped, but the pressurizing is continued until it is cooled, and then released after cooling. In order to prevent foaming between the laminations, after holding at a temperature of the heating plate of 130 ° C. ± 5 ° C. for 20 to 30 minutes,
The temperature of the heating plate is heated to 175 ° C. At this time, a vacuum is created simultaneously with the initial heating. The vacuum condition at that time was 13.3
The pressure is adjusted to KPa (100 Torr), and the atmosphere is released after about 55 minutes. Note that it is not always necessary to make a vacuum state simultaneously with the initial heating.

The adhesive insulating substrate 13 and the adhesive insulating substrate piece 13 ′ having an adhesive function by heating and pressing may be obtained by applying a hot-melt adhesive to both sides of the insulating substrate or by applying a hot-melt adhesive to both sides of the insulating substrate. It is assumed that an adhesive film having a function is attached. A more detailed description will be given of an adhesive film having a hot-melt function attached to both surfaces of the insulating substrate.
A film of a highly insulating epoxy-based adhesive is attached to both sides of an insulating substrate made of Teflon, ceramic, BT resin (trade name of Mitsubishi Gas Chemical Company), glass polyimide, polyimide, glass epoxy resin, or the like. In the case of this epoxy adhesive film, the temperature was raised at 175 ° C. for 60 minutes, and the temperature was raised at a rate of 5 ° C. /
Heating is performed at a pressure of 0.5 MPa to 120 ° C. for a minute and then at a pressure of 1.5 MPa. After heating at 175 ° C. for 60 minutes, the heating is stopped and natural cooling is performed while maintaining the pressure.
The material of the adhesive insulating substrate is selected according to the material of the printed wiring board, or depending on the use of the multilayer printed wiring board, a multilayer printed wiring board is formed by laminating a printed wiring board and an adhesive insulating substrate of different materials. be able to.

When the printed wiring board and the adhesive insulating substrate are bonded at a high temperature in multiple layers, the air pressure in the hollow portion of the adhesive insulating substrate becomes high, and when the high temperature bonding cannot be performed, the air pressure in the hollow portion can be adjusted. A valve or a pressure adjusting pipe (which is formed of an insulating material) communicates with the hollow portion of the adhesive insulating substrate. Further, for adjusting the air pressure in the hollow portion of the adhesive insulating substrate, a groove may be formed in the adhesive insulating substrate so as to communicate with the hollow portion.

According to the present invention, there is provided a multilayer printed wiring board configured as described in claims 1 to 4 and a method for manufacturing a multilayer printed wiring board according to claims 5 to 7. Dielectric constant εr of the adhesive insulating substrate 13
= 3.5-4.8, whereas the hollow part (atmosphere)
Since the dielectric constant εr of the substrate 13a is εr = 1.0, by forming the hollow portion 13a in the adhesive insulating substrate 13 as described above, the signal wiring of the printed wiring board 12 laminated with the adhesive insulating substrate 13 interposed therebetween is obtained. Between conductive foils 11 ', or between conductive foil 11' serving as signal wiring and conductive foil 11 serving as power supply wiring, or conductive foil 11 'serving as signal wiring
The capacitance between the ground and the conductive foil 11 serving as the ground conductive portion is also reduced, so that the signal flowing through the conductive foil 11 'serving as the signal wiring is delayed as in the case where the dielectric constant and the capacitance are large. This eliminates the problem that high-speed processing of signals and improvement in frequency characteristics of signals cannot be dealt with.

[0029]

The multilayer printed wiring board according to claims 1 to 3 of the present invention and the multilayer printed wiring board manufactured by the manufacturing method according to claims 5 to 7 are configured as described above. Therefore, the dielectric constant εr of the hollow portion of the adhesive insulating substrate becomes small, and the conductive foils serving as signal wirings of the printed wiring boards laminated with the adhesive insulating substrate interposed therebetween, or the conductive foils serving as the signal wirings The capacitance between the conductive foil serving as the power supply wiring or between the conductive foil serving as the signal wiring and the conductive foil serving as the ground conductive portion is also reduced, and therefore, as in the case where the dielectric constant and the capacitance are large. To
This eliminates the problem that the signal flowing through the conductive foil serving as the signal wiring is delayed, and it is not possible to cope with high-speed processing of the signal and improvement of the frequency characteristics of the signal. Further, since the multilayer printed wiring board according to claim 4 is configured as described above, a probe contact connected to the printed wiring is provided on the flexible printed wiring board, and an electronic component is provided on the probe contact. When the electronic components are tested (inspected) by pressing the contacts, the contacts of the two can be favorably contacted due to the elasticity of the flexible printed wiring board.

[Brief description of the drawings]

FIG. 1 is a sectional view of a multilayer printed wiring board according to the first aspect of the present invention.

FIG. 2 is a sectional view of a multilayer printed wiring board according to the second aspect of the present invention.

FIG. 3 is a sectional view of a multilayer printed wiring board according to the third aspect of the present invention.

FIG. 4 is a perspective view of a multilayer printed wiring board according to a fourth aspect of the present invention before lamination.

FIG. 5 is a view showing an embodiment of a method for manufacturing a multilayer printed wiring board according to the invention of claim 5;

FIG. 6 is a diagram showing an embodiment of a method for manufacturing a multilayer printed wiring board according to the invention according to claim 6;

FIG. 7 is a diagram showing an embodiment of a method for manufacturing a multilayer printed wiring board according to the invention of claim 7;

FIG. 8 is a sectional view of a conventional multilayer printed wiring board.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Insulating board 11 Conductive foil used as each wiring part 11 'Conductive foil used as a signal wiring part 12 Printed wiring board 12' Flexible printed wiring board 13 Adhesive insulating board 13a Hollow part 13b Peripheral part 14 Multilayer printed wiring board

Claims (7)

[Claims] 1. A multilayer printed wiring board in which a printed wiring board having a conductive foil serving as each wiring portion on at least one surface of an insulating substrate is laminated in multiple layers via an adhesive insulating substrate having an adhesive function by heating and pressing. A multilayer printed wiring board, wherein a hollow portion is provided in a part of the adhesive insulating substrate. 2. The multilayer according to claim 1, wherein the adhesive insulating substrate has a hollow portion at a portion corresponding to a periphery of a conductive foil serving as a signal wiring portion provided on the printed wiring board. Printed wiring board. 3. When the printed wiring board is provided with a conductive foil that becomes a signal wiring portion by increasing the density, a hollow portion is randomly provided on the adhesive insulating substrate. 2. The multilayer printed wiring board according to item 1. 4. The multilayer printed wiring board according to claim 1, wherein an outermost printed wiring board of the plurality of stacked printed wiring boards is a flexible printed wiring board. 5. A printed wiring board having a conductive foil serving as each wiring portion on at least one surface of an insulating substrate, and an adhesive insulating substrate having a hollow part and having an adhesive function by heating and pressing, wherein the printed wiring board is provided. And a bonding and insulating substrate are alternately laminated, and heated and pressed to manufacture a multilayer printed wiring board. 6. A printed wiring board having a conductive foil serving as each wiring portion on at least one surface of an insulating substrate, and a portion corresponding to the periphery of the conductive foil provided as a signal wiring portion provided on the printed wiring board becomes a hollow portion and becomes a heating portion. A multi-layer printed circuit, wherein an adhesive insulating substrate having an adhesive function is prepared by pressing, the printed wiring board and the adhesive insulating substrate are alternately laminated, and a multi-layer printed wiring board is manufactured by heating and pressing. Manufacturing method of wiring board. 7. A printed wiring board in which a piece of an adhesive insulating substrate having an adhesive function is placed on a conductive foil on at least one surface of an insulating substrate by applying heat and pressure, and a hollow portion is provided in a portion except for an outer peripheral portion. A piece of an adhesive insulating substrate having an adhesive function by heating and pressing is placed on a portion including an adhesive insulating substrate having an adhesive function by heating and pressing and a conductive foil on at least one surface of the insulating substrate to be a high-density signal wiring. A printed wiring board placed, an adhesive insulating substrate having a hollow portion in a portion except for an outer peripheral portion, and a printed wiring board having a conductive foil on at least one surface of the insulating substrate are sequentially laminated, and heated and pressed to form the adhesive insulating substrate. A method of manufacturing a multilayer printed wiring board, characterized in that a multilayer printed wiring board having hollow portions randomly provided therein is manufactured.