JPH01307294A - Multilayer printed board - Google Patents

Abstract

PURPOSE:To transmit a signal at high speed by a low dielectric constant, and to use a base substrate consisting of an organic material such as a glass epoxy resin by composing an insulating layer of an adhesive layer made up of a sheet-shaped foamed fluoroplastic resin layer coated or impregnated with a thermosetting resin. CONSTITUTION:An adhesive layer (a prepreg layer) in which a through-hole 34 is bored and worked to a material, in which foamed fluoro-plastics 33 are coated or impregnated with a thermosetting resin 32 under the state of a stage B, by using punching working is pressed and laminated. Pressure bonding is conducted by curing under pressure at the curing temperature (170-200 deg.C) of a conventional thermosetting resin by the pressure laminating of the adhesive layer. Consequently, a substrate consisting of an organic material such as a glass epoxy resin can be employed besides a ceramic substrate as a substrate material, and the degree of freedom of the selection of the substrate is improved. Since the foamed floroplastics are used, the bubbles of air are contained in the foamed fluoroplastics, and the dielectric constant of the foamed fluoroplastics displays a value between the value of 2.1 of fluoroplastics and the value of 1 of the dielectric constant of air, and a signal can be transmitted at high speed.

Description

[Detailed description of the invention] [Table of contents] Overview
・・・・・・・・・・・・・・・・・・・・・3 pages Industrial application fields・・・・・・・・・・・・・・・・・・・・・
・・・・・・・・・Page 3 Conventional technology・・・・・・・・・
・・・・・・・・・・・・・・・・・・・・・・・・
...Page 4 Problems to be solved by the invention...
・・・・・・・・・Means to solve the problem on page 6・
・・・・・・・・・・・・・・・・・・Page 8 Effects・・・・
・・・・・・・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・8 pages Example・
・・・・・・・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・Page 10 Structure and manufacturing method of the first embodiment ・・・・・・Pages 10-12 Structure and structure of the second embodiment Manufacturing method...12~
Page 15 Structure and manufacturing method of the third embodiment...
Pages 15-17 Structure and manufacturing method of the fourth embodiment...
...Pages 17-19 Structure and manufacturing method of the fifth embodiment...
・・・・・・Pages 19-21 Structure and manufacturing method of the 6th embodiment ・・・・・・・・・・・・・・・Page 21 Structure and manufacturing method of the 7th embodiment・・・・・・Pages 21-23 Effects of the invention・・・・・・・・・・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・Page 23 [Summary] Regarding multilayer printed circuit boards, base substrates made of organic materials such as glass epoxy resin that enable high-speed signal transmission with a low dielectric constant. can be used,
The purpose is to create a multilayer printed substrate that has a low elastic modulus, generates little stress, and can form a conductive layer using a chemical plating method such as electroless copper plating without using a sputtering method. In a multilayer printed circuit board having multiple insulating layers, the insulating layer is composed of an adhesive layer made of a sheet-like foamed fluororesin layer coated with or impregnated with a thermosetting resin.

[Industrial application field] The present invention relates to a multilayer printed circuit board.

In order to enable high-density mounting, an insulating layer such as a thermosetting polyimide layer having a conductor layer pattern formed in a predetermined pattern is laminated under pressure on an insulating substrate made of ceramic, and these conductors are laminated under pressure. A multilayer printed circuit board is used in which layer patterns are connected through through holes.

[Conventional technology]

The structure of a conventional multilayer printed circuit board is shown in FIG.

As shown in the figure, a metal pattern 2 is formed on an insulating substrate l made of ceramic as an example of a first conventional multilayer printed circuit board by vapor deposition or sputtering and an etching method using a resist pattern as a mask. Furthermore, a photosensitive polyimide layer 3 is coated on the metal pattern 2, and a predetermined pattern of through holes 4 are formed in the polyimide layer 3 by exposure and development. After forming the metal layer described above on the polyimide layer 3 by sputtering or vapor deposition, this metal layer is formed into a predetermined second layer metal pattern 2. Furthermore, a multilayer printed circuit board having a build-up type structure is formed by laminating a plurality of layers of these metal patterns.

As shown in FIG. 10, a second conventional multilayer printed circuit board for use in high-speed computers has a base material 11 made of glass cloth and fluororesin (polytetrafluoroethylene: PTFE resin). A signal wiring pattern 12 is formed on both sides, and a power wiring pattern 1 is formed on both sides.
A fluororesin (fluorinated ethylene propylene resin: FE) having a lower melting point than the PTFE is used as an adhesive layer between the glass cloth on which 3 is formed and the base material 14 made of fluororesin.
Adhesive layer (prepreg) made by impregnating glass cloth with P resin)
15 are laminated.

Further, as an example of the third conventional multilayer printed circuit board, there is a printed circuit board with a built-in metal core that can supply a large current and has a built-in copper plate with good heat dissipation as a printed circuit board on which an electronic circuit that consumes a large current is mounted. As shown in Figure 11, this structure consists of a copper plate 21 that forms a thick metal core, which is made with holes and whose surface is blackened by oxidizing it with a hot alkaline solution to strengthen the adhesion with the resin layer. After pressing and heating an adhesive layer (prepreg layer) 23 made of glass cloth impregnated with epoxy resin between the foils 22, the through holes 2 are formed.
4 is opened, and electroless plating and electrolytic copper plating are formed in the through hole.

[Problem to be solved by the invention]

However, in the multilayer printed circuit board with the build-up type structure of the first example, the polyimide layer formed on the metal pattern is not formed in a flat state, but has a step difference at the location of the metal pattern. There is a problem that the surface of the printed circuit board having a multilayer structure that is formed is not flat. Furthermore, the curing temperature of the polyimide resin is high, around 400° C., and there is a problem that the organic material substrate made of glass epoxy resin is deformed at the curing temperature. Furthermore, the dielectric constant of the polyimide resin is not lower than 3.5, which impedes high-speed signal transmission.

Furthermore, if a ceramic substrate is used as the substrate, there is a problem that the crank may enter the polyimide resin because the coefficient of thermal expansion is different from that of the polyimide resin described above.

Further, unless the conductor layer on the polyimide resin layer is formed by sputtering, it will have poor adhesion to the resin layer, and chemical plating such as electroless plating cannot be used, making the process complicated.

Further, as an example of a second multilayer printed circuit board, a multilayer printed circuit board used in a high-speed computer has a base material 11 made of glass cloth and a fluororesin (polytetrafluoroethylene: PTFE resin), and a PTFE resin constituting the base material is coated on both sides of the base material 11. PEP resin or PPA resin (perfluoroalkoxy resin), which has an even lower melting point, is used, but both resins have high melting points and are thermoplastic and have a molding temperature of 300°C or higher at which the resin hardens. , P with the highest melting point in the base material
Despite the use of TFH resin, due to its thermoplasticity, the base material begins to soften during pressure and heat molding, causing a problem in which the position of the inner layer circuit of the intermediate layer provided on the base material fluctuates.

Furthermore, when forming a printed circuit board with a built-in metal core as an example of the third multilayer printed circuit board, when opening a through hole in a copper plate that will become a thick metal core, a prepreg layer (made by impregnating a copper plate and an epoxy resin in a glass cloth) is used. This prepreg layer has a high elastic modulus at the interface with the adhesive layer (adhesive layer), so it has the disadvantage of peeling off from the copper plate.

The present invention solves the above-mentioned problems, and aims to provide a multilayer printed circuit board in which a substrate is made of an organic or inorganic material with a low dielectric constant and a low elastic modulus, and which can be easily chemically plated.

[Means to solve the problem]

The multilayer printed circuit board of the present invention, which achieves the second object, has a conductor layer 1 of a predetermined pattern, as shown in the principle diagram of FIG.
In a multilayer printed circuit board having multiple layers of 00 and insulating N200, the insulating layer 200 is an adhesive layer made of a sheet-like foamed fluororesin layer coated with a thermosetting resin layer or impregnated with a thermosetting resin. It is characterized by being

[For production]

The multilayer printed circuit board of the present invention is produced by applying pressure to an adhesive layer (prepreg layer) in which through-holes are formed using a punching process in a material in which a thermosetting resin in a B-stage state is coated or impregnated on foamed fluororesin. Laminate. The product name of this foamed fluororesin is Boretex, and it is manufactured by Japan Boretex Co., Ltd. After dispersing PTFE in a solvent, the fine powder is taken out, pressure molded, and then stretched into a foam that has many air bubbles inside. It is the material.

By laminating the adhesive layer under pressure, the adhesive can be cured under pressure at the curing temperature of conventional thermosetting resins (170 to 200°C). substrates can be used, increasing the degree of freedom in selecting substrates.

Furthermore, by using a foamed fluororesin, air bubbles are contained within the resin, and the dielectric constant of the foamed resin is between the value of 2.1 for the fluororesin and the dielectric constant of 1 for the air in the bubbles. This makes it possible to transmit signals at high speed.

In addition, since the surface of the foamed fluororesin layer contains air bubbles,
It has a rough surface, which improves the degree of adhesion with the thermosetting resin layer coated thereon.

Furthermore, since the elastic modulus is lowered, stress generation in the insulating layer is reduced, and the base substrate can be used for both organic and inorganic materials. Additionally, since little stress is generated, parts can be directly mounted. Further, since the conductor layer pattern can be fixed with a thermosetting resin, circuit formation is facilitated.

In addition, when bonding the resin coated surface under heat and pressure, the surface opposite to the substrate side can transfer the surface of the roughened film, making it easy to form a copper plating layer chemically and using sputtering. A copper plating layer can be easily formed without using any method.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

The structure of the build-up multilayer printed circuit board described above will be explained.

FIG. 2(i) shows a first embodiment of the multilayer printed circuit board of the present invention, and is a sectional view of a single-sided built-up type structure of a built-up type multilayer printed circuit board.

As shown in the figure, a first layer of foamed fluororesin 33 coated with a thermosetting resin 32 such as polyimide resin on both surfaces is laminated on a support vi, 31 made of a copper plate or the like. A through ball 34 is formed in the through ball 34, and an electrolytic copper plating layer 36 is formed inside the through ball 34.

Furthermore, a power circuit pattern 37 consisting of a predetermined pattern of an electroless copper plating layer 35 and an electrolytic copper plating layer 36 is formed on the through hole 34 and the foamed fluororesin layer 33, and a thermosetting resin is coated on both sides of the power circuit pattern 37. A second foamed fluororesin layer 38 coated with 32 is formed, and a signal circuit pattern 39 consisting of an electroless copper plating layer 35 and an electrolytic copper plating layer 36 is formed through the electrolytic copper plating layer 36 in the through hole 34. There is. Furthermore, by etching and removing the metal plate of the support plate 31, a single-sided build-up type pudding plate 5 can be formed.

To form such a printed circuit board, as shown in FIG. 2(a), the second layer of Φ
) After applying a thermosetting resin 32 such as polyimide using a roller coater or the like, and opening the through ball 34 using a punching process as shown in FIG. 2(C), As shown in d), it is bonded to the support plate 31 under pressure and heat.

Next, as shown in FIG. 2(e), after forming an electrolytic copper plating layer 36 in the through hole 34, an electroless copper plating layer N35 is formed on the foamed fluororesin layer 33. Further, as shown in FIG. 2(), a resist pattern 41 is formed on the electroless copper plating layer 35 by photolithography, and then an electrolytic copper plating layer 36 is formed using the resist pattern 41 as a mask.

Furthermore, as shown in FIG.
After forming a power circuit pattern 37 consisting of an electroless copper plating layer 35 and an electrolytic copper plating layer 36 on the 1N foamed fluororesin layer 33 by removing the A second foamed fluororesin layer 38 having a thermosetting resin 32 coated on both sides is laminated under pressure and heat.
) A single-sided build-up multilayer printed circuit board is formed.

A second embodiment of the multilayer printed circuit board of the present invention is shown in FIG. 3(j).
Shown below. This embodiment is a cross-sectional view of a double-sided build-up type structure of a built-up type multilayer printed circuit board.

As shown in the figure, a through-hole land pattern 5 is provided on a printed circuit board 54 on which an intermediate layer 51 and an insulating layer 52 are laminated under pressure.
3 is formed, and on the land patterns 53A and 53B above and below the land pattern 53, the first foamed fluororesin layer 33 is coated with the thermosetting resin layer 32 on both sides.
is formed, and the through hole 3 formed in the resin layer 33
4 is formed with an electrolytic copper plating layer 36, which is connected to the upper and lower land patterns 53A and 53B.

Further, an electroless plating layer 3 is formed on the first layer of foamed fluororesin layer 33.
A power circuit pattern 37 is formed in a predetermined pattern. Furthermore, there is a second
A foamed fluororesin layer 38 of the layer is formed, and the fluororesin layer 38
A thermosetting resin layer 32 is coated on both sides of the plate, and a through hole 34 is further formed.

Regarding the method of forming the multilayer printed circuit board of the second embodiment, as shown in FIG. 3(a), both sides of the first foamed fluororesin layer 33 are thermally cured as shown in FIG. 3(b). Resin 3
2, a through ball 34 is formed by punching or the like as shown in FIG. 2(C).

Next, as shown in FIG. 3(d), the through holes 34 of the first foamed fluororesin layer 33 are aligned with the through hole land pattern 53A on the upper part of the printed circuit board 54. In this case, although not shown, the first layer of the foamed fluororesin layer 3 described above is also included in the land pattern 53B on the lower side of the printed circuit board.
Match the through ball 34 of No. 3. Furthermore, Fig. 3(d)
In the next step, the same operation is performed on the through-hole land pattern on the bottom of the printed circuit board. Furthermore, Fig. 3(e)
As shown in FIG. 3, an electroless plating layer 35 is formed inside the through hole 34 and on the foamed fluororesin layer 33.

Next, as shown in FIG. 3(f), after forming a resist pattern 41 on the foamed fluororesin layer 33, the electrolytic copper plating layer 36 is formed into the through hole 34 using the resist pattern as a mask.
A predetermined pattern is formed inside and on the fluororesin layer 33. Furthermore, as shown in FIG. 3(b), a resist pattern 4 is formed.
1 is removed, and a power circuit pattern 37 consisting of an electroless copper plating layer 35 and an electrolytic copper plating layer 36 is formed on the first foamed fluororesin layer 33.

Furthermore, as shown in FIG. 3(h), a power supply circuit pattern 37 is formed.
A thermosetting resin layer 32 is applied on both sides, and a second foamed fluororesin layer 38 provided with through holes 34 is laminated under pressure and heat. Furthermore, as shown in FIG. 30), after forming the electroless plating layer 35 in the through hole 34, the electroless copper plating layer 35 and the electrolytic copper plating layer 36 are formed on the second layer of foamed fluororesin layer 38. A signal circuit pattern 39 is formed, and a third signal circuit pattern 39 is formed.
A structure shown in figure (j) is formed.

FIG. 4(d) shows a +r4 construction of a third embodiment of the build-up type multilayer printed circuit board of the present invention. As shown in the figure, in this embodiment, a through hole 34 provided in a printed circuit board 54
The through-hole land pattern 56 can be formed directly above the through-hole 34, and a finer pattern can be formed than the land pattern of the second embodiment. .

Further, the first layer of foamed fluororesin layer 33, which has a thermosetting resin layer 32 coated on both sides, is laminated under pressure and heat so that the through holes 34 of the first layer are in contact with each other directly above the land pattern 56, and the inside of the through hole 34 is heated and laminated. An electrolytic plating layer 36 is formed on the surface. A power circuit pattern 37 consisting of an electroless plating layer 35 and an electrolytic plating layer 36 is formed on the first foamed fluororesin layer 33, and an electrolytic plating layer 36 is formed in the through hole 34 on both sides. A second foamed fluororesin layer 38 on which the thermosetting resin layer 32 is formed is laminated under pressure.

In order to form such a multilayer printed circuit board, the steps shown in Fig. 4 (
As shown in a), a printed base in which an intermediate layer 51 and an insulating layer 52 made of polyimide resin are formed under heat and pressure +) A through hole 34 is formed in i54, and an electroless copper plating layer 35 is formed in the through hole 34. After that, the through hole 34 is filled with powdered polyimide resin 55, heated and melted to melt the resin, and then cooled and hardened.

Next, as shown in FIG. 4(b), an electroless copper plating layer and an electrolytic copper plating layer 35A are formed on both sides of the printed circuit board 54. Furthermore, as shown in FIG. 4(C), a through-hole land pattern 56 is formed on the top of the substrate 54, and then a resist film 59 is formed on the bottom of the substrate 54. Next, as shown in FIG. 4(d), it is laminated on the through-hole land pattern 56 on the upper part of the substrate 54 so as to match the through-holes 34 of the first layer of foamed fluororesin layer 33. After build-up, the resist film 59 is removed to form a printed circuit board 54 as shown in FIG. 4(b).
A bottom through-hole land pattern 56 is formed.

The structure of a fourth embodiment of the build-up type multilayer printed circuit board of the present invention is shown in FIG. 5(d).

As shown in the figure, a resist film 59 is formed on the bottom of a printed circuit board 54 in which an intermediate layer 51 and an insulating layer 52 made of polyimide resin are laminated under pressure and heat. A first foamed fluororesin layer 33 coated with a thermosetting resin layer 32
The through holes 34 are stacked so that they match, and an electrolytic copper plating layer 36 is formed in the through holes 34. Further, a power circuit pattern 37 consisting of an electroless copper plating layer 35 and an electrolytic copper plating layer 36 is formed on the first layer of foamed fluororesin layer 33, and an electrolytic plating layer is formed in the through hole 34 on the power circuit pattern 37. The second foamed fluororesin layer 38 on which 36 is formed is laminated under pressure and heat.

To form such a multilayer pudding) plate, the process shown in Fig. 5 (
As shown in a), after forming a through hole 61 in a printed circuit board 54 in which an intermediate layer 51 and an insulating layer 52 are laminated under pressure and heat, an electroless copper plating layer is formed on the surface of the printed circuit board including the inside of the through hole 61. A panel plating layer with a two-layer structure of electrolytic copper plating layer is formed.

Next, as shown in FIG. 5(B), a resist film 59 is formed on the bottom of the printed circuit board 54, and then a resist film 59 of a predetermined pattern is formed on the upper part of the printed circuit board 54. Further, as shown in FIG. 5(C), the panel plating layer is etched using the resist 1959 as a mask to form a through-hole land pattern 53A, and then the above-described first foamed fluororesin layer 33 is formed on the through-hole land pattern 53A. The resin layer 33 is bonded under pressure and heat so that the through holes 34 of the two are aligned with each other.

According to the built-up type printed circuit boards described in the first to fourth embodiments, the dimension in the thickness direction of the metal pattern on the thermosetting resin is applied to the foamed fluororesin and melted during lamination. This results in a flat multilayer printed circuit board that is embedded in thermosetting resin. Furthermore, since the surface of the foamed fluororesin is porous and contains a large amount of air, a metal pattern can be easily formed by a chemical plating method such as an electroless plating method instead of the conventional sputtering method.

Conventionally, prepreg is made of glass cloth impregnated with fluororesin, but since the temperature of heating and pressurizing the adhesive is high, it is recommended to use an organic material such as glass epoxy resin as the base substrate. However, in this example, the bonding temperature was the curing temperature of the thermosetting resin, 170 to 20
Since the temperature is 0°C, an organic material substrate can be used. Furthermore, since the dielectric constant is lowered, high-speed signal transmission can be achieved.

In addition, the prepreg of the present invention has a small elastic modulus and generates little stress during pressurization and heat molding, so it can be used as a base substrate of ceramics, organic materials such as glass epoxy resin, etc.
An inorganic material can be used, and since it contains a large number of bubbles, the adhesive strength during pressurization and heat molding is improved.

Furthermore, a fifth embodiment of the multilayer printed circuit board of the present invention will be described. Figure 6(a) is a sectional view of this embodiment, Figure 6(b)
6(a) is an enlarged view of the main part of FIG. 6(a), which is the opposite of a multilayer printed circuit board with a stripline structure in which a signal pair layer for transmitting signals at high speed is sandwiched between a power supply ground layer.

As shown in FIG. 6(a), a signal pair layer 72 with a strip line structure is formed on a base material 71 made of glass cloth impregnated with fluororesin.
A power ground layer 73 is formed, and this signal pair layer 72
An adhesive layer 75 is formed by applying thermosetting resin 32 to a thickness of about 50 μm on both sides of the foamed fluororesin layer 74 shown in FIG. The structure is such that the resin 32 applied to the surface oozes out to the surface and buries the metal patterns of the signal pair layer 72 and the power supply ground layer 73 in the thickness direction.

According to the printed circuit board structure of this embodiment, since the foamed fluororesin layer 74 is used, air bubbles are contained inside, so the dielectric constant is lower than the original dielectric constant of fluororesin, which is 1.5, which is even lower than the original dielectric constant of 2.1. A prepreg layer is obtained, and the dielectric constant of the printed circuit board formed is significantly lowered, allowing high-speed signal transmission.

Furthermore, a sixth embodiment of the multilayer printed circuit board of the present invention will be described. Fig. 7(a) is a sectional view of this embodiment, Fig. 7(b)
) is an enlarged view of the main part of FIG. 7(a). The difference between this embodiment and the fifth embodiment is that the adhesive layer 76 is formed by impregnating the foamed fluororesin layer 74 with the thermosetting resin 32. . The ratio of impregnating the thermosetting resin 32 into the foamed fluororesin layer 74 is such that when the foamed fluororesin 74 is 40% by weight, the thermosetting resin 3
It is best to mix 2 at a ratio of 60%. When the content of the thermosetting resin 32 relative to the foamed fluororesin increases, the dielectric constant of the adhesive layer 76 formed increases, and when the content of the thermosetting resin 32 decreases, the thermal expansion coefficient of the adhesive layer 76 increases. The thermosetting resin content was set at 60% by weight in order to balance the dimensional stability so that the position of the through hole formed in the multilayer printed circuit board would not change and the dielectric constant of the printed circuit board to be formed. The case is optimal.

Furthermore, a seventh embodiment of the multilayer printed circuit board of the present invention will be described. FIG. 8(e) is a sectional view of this embodiment, FIG. 8(a)
8(e) are sectional views showing the method of manufacturing the printed circuit board of this embodiment.

As shown in FIG. 8(e), the multilayer printed circuit board of this embodiment has a thick copper plate 81 with a thickness of about 0.5 mm that serves as a metal core, and both sides are coated with foamed fluororesin, or foamed fluororesin and thermosetting resin. A glass epoxy resin or a foamed fluororesin of the present invention impregnated with a thermosetting resin is bonded between these copper plates 81 and copper foil 83 for pattern formation. After the layers 84 are laminated and heated and pressed, through holes 85 are formed.

To form such a printed circuit board, as shown in Fig. 8(a), thick copper with a thickness of about 0.5 cm + ff181 is used.
As shown in FIG. 8(b), a foamed fluororesin or a low-elasticity resin 82 made by impregnating a foamed fluororesin with a thermosetting resin such as polyimide is heat-bonded to both surfaces of the substrate.

Next, as shown in FIG. 8(C), a through hole 86 is formed using a punching method or the like, and then, as shown in FIG. 8(d).
As shown in FIG. e
), a through hole 85 is formed.

In this way, by bonding in advance the low elasticity resin 82, which is a foamed fluororesin of the present invention impregnated with a thermosetting resin, on both sides of the copper plate 81, the resin 82 has high adhesive strength, so that the adhesive layer 84
When they are laminated and pressure-molded to integrate, they are sufficiently adhered to the adhesive layer 84. Furthermore, the low modulus resin 82 of this embodiment has a lower modulus of elasticity than the resin conventionally used as prepreg, which is made by impregnating glass fiber with a fluororesin. The resin 82
Since the through-hole can be formed without strain between the copper plate 81 and the resin 82 bonded to its surface, the phenomenon of the resin peeling off from the surface of the copper plate is eliminated, and the through-hole can be formed with high precision. Since it can be machined, the plating liquid can sufficiently penetrate into the through-hole, preventing plating defects inside the through-hole.

〔Effect of the invention〕

As is clear from the above description, the present invention has the effect of providing a multilayer printed circuit board that has a low dielectric constant, is flat, and is easy to manufacture.

[Brief explanation of the drawing]

Figure 1 is a principle diagram of the multilayer printed circuit board of the present invention, and Figure 2 (
From a) to FIG. 2(1) are manufacturing process diagrams of the first embodiment of the multilayer printed circuit board of the present invention, and from FIG. 3(a) to FIG. 3(j) are the manufacturing process diagrams of the second embodiment of the multilayer printed circuit board of the present invention. Manufacturing process diagrams of the embodiment, Figures 4(a) to 4(d) are manufacturing process diagrams of the third embodiment of the multilayer printed circuit board of the present invention, and Figures 5(a) to 5(d). 6(a) is a sectional view of the fifth embodiment of the multilayer printed circuit board of the present invention, and FIG. 6(b) is a sectional view of the fourth embodiment of the multilayer printed circuit board of the present invention. An enlarged view of the main part of Figure (a), Figure 7 (a)
) is a sectional view of the sixth embodiment of the multilayer printed circuit board of the present invention, FIG. 7(b) is an enlarged view of the main part of FIG. 7(a), and FIG.
) to FIG.
Figure 9 is a cross-sectional view showing the structure of a conventional multilayer printed circuit board, Figure 10 is a cross-sectional view showing the structure of a conventional multilayer printed circuit board, and Figure 11 is a structure of a conventional multilayer printed circuit board. FIG. In the figure, 31 is a support plate, 32 is a thermosetting resin, 33 is a first foamed fluororesin layer, 34, 61, 85, 86 are through holes,
35 is an electroless copper plating layer, 36 is an electrolytic copper plating layer, 35
A is an electroless + electrolytic copper plating layer, 37 is a power circuit pattern, 38 is a second foamed fluororesin layer, 39 is a signal circuit pattern, 51 is an intermediate layer, 52 is an insulating layer, 53A, 53B, 5
6 is a through hole land pattern, 54 is a printed circuit board, 55 is polyimide resin, 57 and 83 are copper foils, 58 is a metal film, 59 is a resist film, 71 is a base material, 72 is a signal bare layer, 73 is a power ground layer , 74 is foamed fluororesin, ?
5, 76, and 84 are adhesive layers, 81 is a copper plate, 82 is a low elastic resin, 100 is a conductive layer, and 200 is an insulating layer. Throat spring trigram e) 4-Multiple 7/G) Tong 1 (Call 5 lPPb0
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Claims (3)

[Claims] (1) Predetermined pattern of conductor layer (100) and insulating layer (2)
00) in a multilayer printed circuit board, the insulating layer (200) is a sheet-like foamed fluororesin layer (33, 38) coated with or impregnated with a thermosetting resin (32).
, 74, 76). (2) Base material (71) on which a power ground layer (73) was formed
and a base material (71) on which a signal wiring pair layer (72) is formed, and an adhesive layer (7) consisting of a sheet-like foamed fluororesin layer (74) coated or impregnated with the thermosetting resin (32).
5) The multilayer printed circuit board according to claim 1, wherein the multilayer printed circuit board has the following features. (3) Both sides of the inner layer metal plate (81) are covered with an adhesive layer consisting of a foamed fluororesin layer (82) or a resin layer in which the foamed fluororesin layer is impregnated with a thermosetting resin.
2. The multilayer printed circuit board according to claim 1, wherein the adhesive layer (84) is laminated on both sides of the board.