JP2007027172A - Multilayered circuit board and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multilayered circuit board and its manufacturing method wherein high frequency transmission characteristics of a transmission line are improved together with an improvement of the flexibility of a design. <P>SOLUTION: The multilayered circuit board excellent in high speed data transmission characteristics is provided by including: a first substrate 10a having a pair of first earth electrodes 14a provided in parallel at the left and right of a signal electrode 13 and its signal electrode 13; a second substrate 10b having a pair of second earth electrodes 14b provided at a position facing a first earth electrode 14a; a conductor 15 provided between the first substrate 10a and the second substrate 10b for connecting between the first earth electrode 14a of the first substrate 10a and the second earth electrode 14b of the second substrate 10b; and a space part 12 provided by the conductor 15 around at least the signal electrode 13. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a multilayer circuit board that is connected to a semiconductor element or the like and constitutes an electric circuit, and more particularly to a multilayer circuit board that is used at a high frequency and a method for manufacturing the same.

  In recent years, there has been a growing demand for smaller, lighter, higher functionality and higher performance electronic devices on the market. For this reason, circuit boards used in electronic devices are also required to have high-speed and large-capacity data transmission and high-performance circuit boards as well as miniaturization and high density.

  In general, the transmission speed of an electric signal transmitted through a signal electrode is limited by a time constant determined by wiring electrode resistance and stray capacitance. Therefore, for high-speed data transmission, it is necessary to further reduce the wiring electrode resistance and stray capacitance to improve the transmission speed. In general, when the wiring is formed with a conductive paste, the electrode resistance is larger than that of Cu (copper) foil, etc., so that a normal multilayer substrate configuration is not suitable for high-speed data transmission. It was difficult to realize high-speed data transmission.

  In addition, high-speed data transmission requires a low dielectric constant and low loss circuit board and a wiring circuit configuration that does not increase the stray capacitance in order to reduce the coupling capacitance and stray capacitance between the electronic element and the wiring electrode. In addition, when high-speed data transmission is performed using wiring electrodes formed on a circuit board, in order to reduce loss due to reflection and unnecessary radiation noise, transmission lines such as wiring electrodes on a circuit board and connection devices (for example, ICs) The characteristic impedance matching is important.

  One solution to improve these problems is a high-speed transmission method that uses a wiring electrode configuration such as a microstrip line or a coplanar line. However, since a transmission line such as a wiring electrode is formed on the surface of a circuit board, a small size is required.・ We cannot satisfy the demand for higher density.

  On the other hand, there is a strip line in which a signal electrode is embedded in the center of a substrate and its upper and lower surfaces are sandwiched between ground electrodes.

  However, since the position of the signal electrode and the upper and lower ground electrodes, the thickness of the dielectric layer, and the like are greatly affected by the process, the strip line is difficult to realize a desired characteristic impedance and to be easily formed. Further, since the upper and lower sides of the signal electrode are sandwiched between dielectric layers that are substrate materials, the stray capacitance is increased, and the speeding up of the signal electrode is limited.

  In order to improve the above problem, a method of effectively reducing the dielectric constant by forming a cavity inside a circuit board has been proposed.

  As an example, in a ceramic multilayer circuit board provided with a conductor pattern, at least one layer in the multilayer structure is formed of an air layer, a plurality of columnar structures are provided in the air layer, and the conductor pattern is interposed via the air layer. Is disclosed (for example, refer to Patent Document 1). Thus, an air layer, which is a low dielectric constant layer, is formed at a desired position as a dielectric layer, so that an inductor and a high impedance line excellent in high frequency transmission characteristics can be inscribed in a small size.

As another example, a space portion is formed in the ceramic dielectric substrate along the signal transmission direction, a strip conductor is placed on one inner wall surface of the upper wall surface and the lower wall surface facing each other across the space portion, and the other The thing which formed the high frequency transmission line by forming a ground conductor in an inner wall surface is disclosed (for example, refer patent document 2). This makes it possible to improve the transmission characteristics of the transmission line by forming a space or a groove in the circuit board or on the surface and making the strip conductor and the ground conductor (ground electrode) face each other. It can be used as a line filter.
JP 2003-304064 A JP 2004-201135 A

  However, in the multilayer circuit board in Patent Document 1, an air layer is formed by supporting the upper and lower substrates in a point-like manner with insulating columnar structures, thereby making one layer itself an air layer (excluding the columnar structures). Yes. Therefore, even if a high-frequency circuit is formed in part, the degree of freedom in designing circuits and wiring electrodes arranged inside the circuit board is greatly limited, and there is a problem that it is not possible to cope with downsizing and high density. In addition, since a green sheet is laminated and fired as a circuit board, there is a problem that it cannot be applied to a resin substrate or the like.

  Further, in the multilayer circuit board in Patent Document 2, a space is formed inside the ceramic dielectric substrate, a strip conductor is provided on the upper wall surface with the space being sandwiched, and a ground conductor is provided on the lower wall surface to form a microstrip line. ing. Therefore, although the transmission characteristics of the transmission line can be enhanced, the signal electrode and the ground electrode of the microstrip line are individually formed on the circuit board facing each other, so the degree of freedom of design is limited, and the surface of the high-frequency component etc. There was a problem that it could not be implemented. Further, since the ceramic substrate is formed by laminating and firing multiple green sheets, there is a problem that it cannot be applied to a resin substrate or the like.

  The present invention has been made to solve the above-described problems, and provides a multilayer circuit board suitable for high-speed data transmission and a method for manufacturing the same, by improving high-frequency transmission characteristics of a transmission line and improving design flexibility. For the purpose.

  In order to solve the problems as described above, a multilayer circuit board of the present invention includes a first board having at least a signal electrode and a pair of first ground electrodes provided in parallel to the left and right of the signal electrode, At least a second substrate having a pair of second ground electrodes provided at positions opposed to the first ground electrode, the first ground electrode of the first substrate and the second substrate It has a configuration in which at least a conductor is connected to the second ground electrode and a space is provided around the signal electrode by the conductor.

  According to such a configuration, a coplanar line with ground electrodes on the left and right sides of the signal electrode is formed, and the space around the coplanar line is formed as an air layer, thereby realizing low dielectric constant and low dielectric loss. In addition, the high frequency transmission characteristics can be improved. In addition, since the signal electrode can be easily formed by a strip line or a coplanar line, the degree of freedom in design is improved and the design of the multilayer circuit board for high frequency can be facilitated.

  Further, the second ground electrode may be formed to have a width between a pair of first ground electrodes facing each other, and the second ground electrode may be formed on a second substrate facing the signal electrode.

  According to such a configuration, the signal electrode is configured to surround the periphery with the ground electrode through the space portion, thereby reducing the radiation of unnecessary radiation noise, improving the high-frequency transmission characteristics, and improving reliability. A multilayer circuit board having excellent properties can be obtained.

  Further, the signal electrode may be formed of a pair of a first signal electrode and a second signal electrode formed in parallel.

  According to such a configuration, the signal electrode is formed by a pair of the first signal electrode and the second signal electrode formed in parallel, so that a high-frequency circuit having a differential circuit configuration can be configured. Since the differential circuit configuration can cancel each other's electromagnetic noise, it is possible to obtain a multilayer circuit board with low reflection noise that operates by a low-voltage high-frequency signal.

  The multilayer circuit board according to the present invention includes at least a first substrate having at least a first signal electrode and a pair of first ground electrodes provided in parallel to the left and right of the first signal electrode, and at least a first signal electrode. At least a second signal electrode provided at a position opposite to the signal electrode and the first ground electrode, and a second substrate having a pair of second ground electrodes. A conductor that connects the second ground electrode of the second substrate and the second ground electrode of the second substrate, and a space provided by the conductor around at least the first signal electrode and the second signal electrode facing each other. Have.

  According to such a configuration, a pair of coplanar lines formed on the first substrate and the second substrate are opposed to each other to form a differential circuit configuration, thereby improving high-frequency transmission characteristics and canceling each other's electromagnetic noise. Thus, it is possible to obtain a multilayer circuit board that operates even with a low-voltage high-frequency signal.

  Furthermore, the first substrate and the second substrate may be flexible substrates.

  According to such a configuration, since the first substrate and the second substrate are flexible substrates, it is possible to form a multilayer circuit substrate having a wiring electrode formed of a conductive paste or the like at a low cost.

  Furthermore, at least one of the first substrate and the second substrate may be a double-sided circuit board having a conductive via.

  According to such a configuration, at least one of the first substrate and the second substrate is a double-sided circuit substrate having conductive vias, so that highly integrated circuit boards are stacked in multiple layers and predetermined by the conductive vias. Since the electrodes are connected to each other, a small-sized and high-density multilayer circuit board can be obtained.

  The multilayer circuit board according to the present invention has a first circuit block having at least a signal electrode and a pair of first ground electrodes provided in parallel to the left and right of the signal electrode, and is opposed to at least the first ground electrode. And a flexible circuit board provided with at least a second circuit block having a pair of second ground electrodes provided at a position where the flexible circuit board has at least a first ground electrode and a second circuit block. A circuit board having a conductor formed on at least one of the second ground electrodes of the circuit block, and folding the flexible substrate to connect the first ground electrode and the second ground electrode via the conductor. In addition, a configuration in which at least a space portion is provided by a conductor around the signal electrode is included.

  According to such a structure, a multilayer circuit board provided with the coplanar line | wire which has the space part excellent in the high frequency transmission characteristic can be obtained by folding a flexible substrate.

  The multilayer circuit board according to the present invention includes a first circuit block having at least a first signal electrode and a pair of first ground electrodes provided in parallel to the left and right of the first signal electrode, A pair of second ground electrodes provided on the surface facing the first ground electrode, and a second signal electrode and a second signal electrode provided on the other surface in parallel to the left and right At least a second circuit block having a pair of third ground electrodes and at least a third circuit block having a pair of fourth ground electrodes provided at positions opposed to the third ground electrode are provided. A flexible substrate, the flexible substrate including at least one of a first ground electrode of the first circuit block and a second ground electrode of the second circuit block; a third ground electrode of the second circuit block; Of the fourth ground electrode of the circuit block of 3 At least one conductor is formed, the flexible substrate is folded, and the first ground electrode, the second ground electrode, the third ground electrode, and the fourth ground electrode are respectively connected via the conductor. In addition to the connection, the first signal electrode and the second signal electrode have a configuration in which a space is provided at least around the conductor.

  According to such a configuration, a plurality of flexible boards can be folded and overlapped to form a multilayer circuit board in a lump, so that the number of steps can be reduced, and high-frequency small-sized and high-density can be manufactured at low cost.

  The method for manufacturing a multilayer circuit board according to the present invention includes a step of forming at least a signal electrode and a pair of first ground electrodes provided in parallel to the left and right of the signal electrode on the first substrate, and at least a first Forming a pair of second ground electrodes provided on the second substrate at positions opposite to the ground electrodes of the first substrate, a first ground electrode of the first substrate, and a second ground of the second substrate Connecting the electrodes with a conductor and forming a space around the signal electrode.

  By this method, a high-frequency multilayer circuit board on which strip lines and coplanar lines are easily formed can be easily manufactured.

  The method for manufacturing a multilayer circuit board according to the present invention includes a first circuit block having at least a signal electrode and a pair of first ground electrodes provided in parallel to the left and right of the signal electrode, and at least a first ground. Forming at least a second circuit block having a pair of second ground electrodes provided at positions facing the electrodes on at least a flexible substrate; and first grounding of at least the first circuit block of the flexible substrate Forming a conductor on at least one of the electrode and the second ground electrode of the second circuit block, folding the flexible substrate, and connecting the first ground electrode and the second ground electrode via the conductor And at least forming a space around the signal electrode.

  According to this method, since the flexible substrate is folded and overlapped and formed in a lump, the number of steps can be reduced and a multilayer circuit substrate for high frequency can be manufactured at low cost.

  The method for manufacturing a multilayer circuit board according to the present invention includes a first circuit block having at least a first signal electrode and a pair of first ground electrodes provided in parallel to the left and right of the first signal electrode; , Having a pair of second ground electrodes provided on one surface at a position facing the first ground electrode, and parallel to the left and right of the second signal electrode and the second signal electrode on the other surface A second circuit block having a pair of third ground electrodes provided, and a third circuit block having a pair of fourth ground electrodes provided at a position opposed to at least the third ground electrode; At least one of the first ground electrode of the first circuit block and the second ground electrode of the second circuit block, and the third circuit block of the second circuit block. Of the ground electrode and the third circuit block Forming a conductor on at least one of the four ground electrodes, folding the flexible substrate, and connecting the first ground electrode, the second ground electrode, the third ground electrode, and the fourth ground electrode to the conductor. And a step of forming at least a space around the first signal electrode and the second signal electrode.

  By this method, a plurality of flexible substrates can be folded and overlapped and formed in a lump, so that by reducing the number of steps, a multilayer circuit substrate for high frequency can be manufactured at low cost with high density.

  Each configuration and manufacturing method described above can be combined with each other without departing from the gist of the present invention.

  In the multilayer circuit board of the present invention, a space is provided inside the multilayer circuit board, and coplanar lines having ground electrodes on the left and right sides of the signal electrode are formed in the space, thereby improving the high-frequency transmission characteristics and improving the design flexibility. A high multilayer circuit board can be easily realized.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 is a cross-sectional view illustrating an outline of a multilayer circuit board according to Embodiment 1 of the present invention.

  In FIG. 1, the multilayer circuit board has a structure in which at least a first substrate 10a and a second substrate 10b are stacked so as to face each other.

  The first substrate 10a and the second substrate 10b made of, for example, a resin substrate have a predetermined wiring circuit layer 11 on at least one surface. At the same time, on the surface of the first substrate 10a facing the second substrate 10b, at least the signal electrode 13 and a pair of first ground electrodes (ground electrodes) provided parallel to the left and right of the signal electrode 13 are provided. A coplanar line consisting of 14a is formed. Similarly, a pair of second ground electrodes 14b is formed on the surface of the second substrate 10b facing the first substrate 10a at least at a position facing the first ground electrode 14a.

  In addition, at least one of the first substrate 10a and the second substrate 10b is a double-sided circuit board, and conductive vias 16 that electrically connect the wiring circuit layers 11 on both sides are formed in order to form a multilayer circuit board. Have.

  Then, the signal electrode 13, the first ground electrode 14a, and the like constituting the coplanar line are connected to the wiring circuit layer 11 formed on the first substrate 10a and the second substrate 10b through the conductive via 16.

  Although not shown, the signal electrode 13, the first ground electrode 14a and the like are connected to the conductive via 16 and drawn to the outer surface of the multilayer circuit board, and the wiring circuit layer 11 formed on the surface of the multilayer circuit board It is good also as a structure connected with the electronic component mounted. As a result, a multilayer circuit board corresponding to miniaturization and high density can be obtained.

  The first ground electrode 14 a of the first substrate 10 a and the second ground electrode 14 b of the second substrate 10 b are electrically connected by the conductor 15. With this conductor 15, a space portion (hollow portion or hollow portion) 12 is formed around the signal electrode 13. Here, it is preferable that the space portion 12 has a structure that does not become a sealed space in order to reduce the influence of air expansion or the like in the thermal history during the production of the multilayer wiring board. For example, it is realizable by making at least one end of the space part 12 into an open end structure.

  A multilayer circuit board having a high-frequency transmission line such as a coplanar line having a signal electrode 13 and a pair of first ground electrodes 14a on the left and right sides thereof is obtained on the surface of the first substrate 10a facing through the space portion 12. It is done.

  According to the first embodiment of the present invention, the signal electrode 13 and the pair of first ground electrodes 14a are disposed inside the multilayer circuit board through the space portion 12 formed of an air layer having a relative dielectric constant of 1. A high-frequency transmission line coupled electromagnetically is formed. Therefore, when transmitting a high-frequency signal, the transmission loss can be reduced due to the decrease in dielectric loss (tan δ) and the low relative dielectric constant caused by the space 12. As a result, the transmission characteristics are not deteriorated by the substrate made of a high dielectric constant material necessary for the conventional microstrip line or strip line, so that the high frequency transmission characteristics can be improved.

  In addition, since the signal electrode 13 and the first ground electrode 14a can be formed on one surface of the first substrate 10a, for example, the degree of freedom in designing each electrode is increased, and the design of the multilayer circuit board is facilitated. .

  In addition, as a board | substrate material which comprises the 1st board | substrate 10a and the 2nd board | substrate 10b, PPE (polyphenylene ether), BT resin (bismaleimide triazine), an epoxy resin, a polyimide resin, a fluororesin, a phenol resin etc., for example A resin material is used.

Further, when a substrate excellent in bending strength or the like is desired as the multilayer circuit substrate, it is desirable to use a substrate in which an inorganic material is combined with a resin material. In that case, as the inorganic material to be compounded with the resin material, a composite material to which fillers such as SiO ₂ , Al ₂ O ₃ , AlN, aluminum borate are added in addition to glass fiber woven fabric or nonwoven fabric is used. Can do.

  Moreover, as electrode materials, such as the signal electrode 13, the 1st ground electrode 14a, and the 2nd ground electrode 14b, it is 1 type chosen from the group of copper, gold | metal | money, silver, aluminum, nickel, or the alloy containing 2 or more types A metal foil such as a material, a metal film, a metal plating film, desirably copper, or an alloy material containing copper can be used. Further, a conductive paste in which the above metal particles are mixed with a resin binder or the like can also be used.

  Below, the manufacturing method of the multilayer circuit board in Embodiment 1 of this invention is demonstrated using FIG.

  FIG. 2 is a process cross-sectional view for explaining one aspect of the method for manufacturing a multilayer circuit board in the first embodiment of the present invention.

  First, as shown in FIG. 2A, a signal electrode 13 serving as a strip conductor and the left and right sides of the signal electrode 13 are formed on at least one surface of a first substrate 10a made of, for example, a resin material provided with conductive vias 16. A pair of first ground electrodes 14a are wired in parallel to form a so-called coplanar line. Further, along with these formations, a predetermined wiring circuit layer 11 other than the signal electrode 13 and the first ground electrode 14a is formed on one or both surfaces of the first substrate 10a.

  Here, the signal electrode 13, the first ground electrode 14a, and the wiring circuit layer 11 can be formed by an etching method such as copper foil, a screen printing method such as a conductive paste, or a plating method. . Note that these forming methods can be used in the same manner in the embodiments described below.

  Next, as shown in FIG. 2B, for example, a predetermined amount of conductive material is formed on the surface of the wiring circuit layer 11 such as the connection electrode connected to the first ground electrode 14a and the conductive via 16 of the first substrate 10a. The conductor 15 is formed by application or transfer of an adhesive or the like or screen printing.

  Although not shown when the conductor 15 is formed, a portion that does not require conduction between the first substrate 10a and the second substrate 10b except for a space described below is insulated, for example. The resin layer may be formed with a conductive sheet or an insulating adhesive. Thereby, it is possible to obtain a great effect as a prevention of a short circuit due to the flow of the conductor 15, an improvement in adhesive strength between the first substrate 10a and the second substrate 10b, and a reinforcing member for the space portion.

  Next, as shown in FIG. 2C, at least a first ground electrode 14a is formed on at least one surface of the second substrate 10b made of a resin material provided with, for example, a conductive via 16, using a similar method. A pair of second ground electrodes 14b are formed at positions facing each other. Moreover, you may form the predetermined wiring circuit layer 11 in the 2nd board | substrate 10b as needed.

  The positions of the first substrate 10a and the second substrate 10b are set so that at least the first ground electrode 14a of the first substrate 10a and the second ground electrode 14b of the second substrate 10b face each other. Place them together.

  Next, as shown in FIG. 2 (d), the first substrate 10a and the second substrate 10b arranged to face each other are kept at a predetermined interval by using, for example, a pressurizing device (not shown). While applying pressure, apply pressure. Then, the conductor 15 and the resin layer (provided if necessary) are completely cured by heat treatment. At this time, the treatment is performed, for example, at a heating temperature of 200 ° C. and under a pressure of about 0.1 MPa. Thus, the first ground electrode 14a of the first substrate 10a and the second ground electrode 14b of the second substrate 10b are connected by the conductor 15, and the predetermined conductive vias 16 are also connected by the conductor 15. To do.

  Then, the first substrate 10a and the second substrate 10b are pressure-bonded at a predetermined interval, so that a predetermined amount is provided between the first substrate 10a and the second substrate 10b and around the signal electrode 13. A multilayer circuit board in which the space portion 12 having the following interval is formed is obtained. In addition, although not shown in figure, it is good also as a structure reinforced with an insulating member other than the said resin layer of a multilayer circuit board as needed, for example.

  FIG. 3 is a cross-sectional view illustrating an outline of another example of the multilayer circuit board according to Embodiment 1 of the present invention. In FIG. 3, the same components as those in FIG.

  3 is different from the multilayer circuit board of FIG. 1 in that a third board 30 is laminated on a first board 10a and a second board 10b to form a multilayer circuit board structure consisting of three layers. .

  First, as shown in FIG. 3, a first substrate 10a and a second substrate 10b formed in the same manner as in FIG. 1 are stacked.

  Next, a third substrate 30 provided with a coplanar line including at least a signal electrode 33 and a pair of third ground electrodes 34a provided in parallel to the left and right of the signal electrode 33 is laminated thereon. A multilayer circuit board having a three-layer structure is formed.

  Here, on the back surface (the surface facing the third substrate 30) of the first substrate 10a, at least a pair of fourth electrodes provided at positions facing the third ground electrode 34a of the third substrate 30. Ground electrode 34b is provided. The first substrate 10a, the second substrate 10b, and the third substrate 30 are provided with predetermined wiring circuit layers 11 and conductive vias 16 as necessary.

  Then, the first ground electrode 14a of the first substrate 10a and the second ground electrode 14b of the second substrate 10b, the fourth ground electrode 34b of the first substrate 10a and the third ground electrode of the third substrate 30 are provided. The ground electrode 34 a is connected via the conductor 15. As a result, the space 12 is formed around the signal electrode 13 and the space 32 is formed around the signal electrode 33, so that a multilayer circuit board having three layers as shown in FIG. 3 is obtained. In addition, the space part may be formed in addition to the space parts 12 and 32 provided around the signal electrodes 13 and 33, and may be filled with, for example, a resin layer.

  According to another example of the first embodiment of the present invention, by providing a coplanar line on a plurality of substrates, it is possible to obtain a multilayer circuit substrate having a smaller size and higher density and excellent in high frequency transmission characteristics.

  The multilayer circuit board having three layers in FIG. 3 can be laminated and formed by the same method as the manufacturing method of the two-layer board shown in FIG.

  In FIG. 3, a multilayer circuit board having three layers has been described as an example, but the present invention is not limited to this. For example, even a multilayer circuit board configuration composed of a plurality of four or more layers can be formed in the same manner, and the same effect can be obtained.

(Embodiment 2)
FIG. 4 is a cross-sectional view for explaining the outline of the multilayer circuit board according to Embodiment 2 of the present invention. In FIG. 4, the same components as those in FIG.

  FIG. 4 shows that the pair of second ground electrodes 14b shown in FIG. 1 is formed by one second ground electrode 40 having a width equivalent to that between the pair of opposing first ground electrodes 14a. Is different.

  That is, as shown in FIG. 4, the second ground electrode 40 of the second substrate 10b is formed with a width L between a pair of opposing first ground electrodes 14a. At least the pair of first ground electrodes 14 a of the first substrate 10 a and the second ground electrode 40 of the second substrate 10 b are connected via the conductor 15, and a space around the signal electrode 13. Part 42 is formed. Therefore, the periphery of the signal electrode 13 is surrounded by the space 42 by the pair of first ground electrodes 14a of the first substrate 10a and the second ground electrode 40 of the second substrate 10b in three directions. A multilayer circuit board having a high-frequency transmission line having the above-described configuration is obtained.

  With this configuration, the electromagnetic wave noise radiated by the high-frequency signal transmitted through the signal electrode 13 is shielded (shielded) by the ground electrodes provided on the three sides, so that unnecessary radiation noise radiated from the multilayer circuit board to the outside is reduced. Can be reduced. Further, a ground electrode is further formed on the inner layer of the first substrate 10a at the position where the signal electrode 13 is formed or on the opposite surface of the first substrate 10a facing the signal electrode 13, and the other is connected through a conductive via or the like. It is good also as a structure connected with a ground electrode. Thereby, since the four sides of the signal electrode can be shielded by the ground electrode, the shielding effect can be further enhanced.

  According to Embodiment 2 of the present invention, the signal electrode has a configuration in which the periphery is surrounded by the ground electrode through the space portion, so that radiation of unnecessary radiation noise can be greatly reduced, and high-frequency transmission characteristics can be achieved. Can be further improved.

(Embodiment 3)
FIG. 5 is a cross-sectional view for explaining the outline of the multilayer circuit board according to Embodiment 3 of the present invention. In FIG. 5, the same components as those in FIG.

  FIG. 5 is different from the signal electrode 13 shown in FIG. 1 in that it includes a pair of a first signal electrode 53a and a second signal electrode 53b formed in parallel.

  As shown in FIG. 5, the signal electrode 53 is wired on the first substrate 10a in parallel as a pair of the first signal electrode 53a and the second signal electrode 53b, and a pair of first signal electrodes. A pair of first ground electrodes 14a are formed on the left and right of 53a and the second signal electrode 53b.

  Similarly to FIG. 1, a pair of second ground electrodes 14b is formed on the second substrate 10b at a position facing the first ground electrode 14a.

  Then, the first substrate 10 a and the second substrate 10 b are opposed to each other, and predetermined electrodes such as the first ground electrode 14 a and the second ground electrode 14 b are connected by the conductor 15. As a result, a space 52 is formed around the pair of first signal electrode 53a and second signal electrode 53b.

  As described above, a high-frequency transmission line having a differential circuit configuration, for example, a + signal line and a − signal line, respectively, is provided by the pair of first signal electrode 53a and second signal electrode 53b formed in the space 52. A multilayer circuit board is obtained. The differential circuit having the matched differential impedance can suppress signal degradation and reflection noise to an extremely low level and reduce transmission loss. As a result, a multilayer circuit board having excellent high-frequency transmission characteristics can be obtained.

  According to the third embodiment of the present invention, a high-frequency transmission line having a differential circuit configuration can be configured by a signal electrode including a pair of first signal electrodes and second signal electrodes formed in parallel. Therefore, since a pair of signal electrodes constituting the differential circuit can cancel each other's electromagnetic noise, a multilayer circuit board corresponding to high-speed data transmission can be obtained with low reflection noise operated by a low-voltage high-frequency signal. .

(Embodiment 4)
FIG. 6 is a cross-sectional view for explaining the outline of the multilayer circuit board according to Embodiment 4 of the present invention. In FIG. 6, the same components as those in FIG.

  FIG. 6 shows a pair of second signal electrode 63b and a pair of first signal electrodes 63a and a pair of first ground electrodes 64a on the second substrate 60b. The difference is that at least the second ground electrode 64b is provided.

  As shown in FIG. 6, the second signal electrode 63b is formed on the second substrate 60b at a position facing the first signal electrode 63a of the first substrate 60a. Further, a pair of second ground electrodes 64b are formed at positions facing the pair of first ground electrodes 64a formed on the left and right sides of the first signal electrode 63a of the first substrate 60a.

  A first substrate 60a having a first signal electrode 63a and a pair of first ground electrodes 64a, a second signal electrode 63b provided at a position facing them, and a pair of second grounds The second substrate 60 b having the electrode 64 b is connected via the conductor 15. As a result, a space 62 is formed around the first signal electrode 63a and the second signal electrode 63b facing each other. Then, a pair of coplanar lines are formed to face each other on the first substrate 60a and the second substrate 60b with the space 62 interposed therebetween.

  As a result, the first signal electrode 63a and the second signal electrode 63b provide a multilayer circuit board having a high-frequency transmission line having a differential circuit configuration, for example, a + signal line and a − signal line, respectively. That is, it is possible to realize a multilayer circuit board with excellent high frequency transmission characteristics in which signal degradation and reflection noise are suppressed to a lower level by a differential circuit in which differential impedance is matched.

  According to the fourth embodiment of the present invention, the first signal electrode formed on the first substrate and the signal electrode formed by a pair of the second signal electrode formed on the second substrate are opposed to each other. A high-frequency transmission line having a differential circuit configuration arranged in the manner described above can be configured. Therefore, since a pair of signal electrodes constituting the differential circuit can cancel each other's electromagnetic noise, a multilayer circuit board corresponding to high-speed data transmission can be obtained with low reflection noise that operates by a low-voltage high-frequency signal. .

  In each of the above embodiments, the first substrate and the second substrate have been described as rigid substrates. However, the first substrate and the second substrate may be flexible substrates. Thereby, since the 1st board and the 2nd board are flexible boards, while being excellent in flexibility, a thin multilayer circuit board can be obtained.

(Embodiment 5)
FIG. 7 is a cross-sectional view for explaining the outline of the multilayer circuit board according to Embodiment 5 of the present invention. In FIG. 7, the same components as those in FIG.

  In FIG. 7, the multilayer circuit board is composed of a flexible substrate 70 having a first circuit block 71a and a second circuit block 71b made of, for example, a resin substrate.

  The first circuit block 71a provided on the flexible substrate 70 includes at least a signal electrode 73 serving as a strip conductor and a pair of first ground electrodes 74a provided in parallel to the left and right of the signal electrode 73. A coplanar line.

  Further, the second circuit block 71b provided in a region different from the first circuit block 71a of the flexible substrate 70 is folded and faces the first ground electrode 74a on the surface facing the first ground electrode 74a. A pair of second ground electrodes 74b are provided at opposing positions.

  The ground electrodes are electrically connected to each other by the conductor 15 provided on at least one of the first ground electrode 74a of the first circuit block 71a and the second ground electrode 74b of the second circuit block 71b. Has been.

  In addition, the flexible substrate 70 is provided with a spacer 75 to bend and hold the first circuit block 71a and the second circuit block 71b of the folded flexible substrate 70 at a constant interval as necessary. It is done.

  Next, the flexible substrate 70 is folded while being held at a constant interval by the spacer 75, and the first ground electrode 74 a and the second ground electrode 74 b are connected via the conductor 15, thereby causing the signal electrode 73. A multilayer circuit board having a high-frequency transmission line in which a space 72 is formed around is obtained.

  According to the fifth embodiment of the present invention, the same effects as those of the first embodiment can be obtained, and the flexible substrate can be folded and formed at a time, so that a thin and inexpensive multilayer circuit substrate can be realized.

  In addition, the wiring circuit layer 11 may be provided in the bent part (curved part of FIG. 7) of the flexible substrate 70 to connect the first circuit block 71a and the second circuit block 71b. Alternatively, the bent portion (curved portion in FIG. 7) of the flexible substrate 70 may be cut off with, for example, a dicing saw or the like to obtain the multilayer circuit board configuration shown in FIG.

  Below, the manufacturing method of the multilayer circuit board in Embodiment 5 of this invention is demonstrated using FIG.

  FIG. 8 is a process cross-sectional view for explaining one aspect of a method for manufacturing a multilayer circuit board in Embodiment 5 of the present invention.

  First, as shown in FIG. 8A, a plurality of holes penetrating the flexible substrate 70 are formed, and the conductive via 16 is formed by filling the conductive paste and curing the embedded paste. Then, on at least one surface of the flexible substrate 70, as the first circuit block 71a, a signal electrode 73 serving as a strip conductor and a pair of first ground electrodes 74a on the left and right sides of the signal electrode 73 are wired in parallel. Thus, a so-called coplanar line is formed. Further, in a region different from the first circuit block 71a of the flexible substrate 70, the second circuit block 71b is located at a position facing at least the first ground electrode 74a on the surface facing the first ground electrode 74a. A pair of second ground electrodes 74b is formed. Further, a predetermined wiring circuit layer 11 other than the signal electrode 73, the first ground electrode 74a, and the second ground electrode 74b is formed on the flexible substrate 70.

  Next, as shown in FIG. 8B, at least a predetermined amount of the surface of the wiring circuit layer 11 such as the connection electrode connected to the first ground electrode 74a and the conductive via 16 of the first circuit block 71a is provided. The conductor 15 is formed by application or transfer of a conductive adhesive or screen printing.

  Next, as shown in FIG. 8C, for example, a columnar spacer 75 having a certain height is disposed at a predetermined position of the flexible substrate 70. As the spacer 75, an insulating resin, a metal on which an insulating film is formed, or the like can be used.

  Next, as shown in FIG. 8D, alignment is performed so that at least the first ground electrode 74a of the first circuit block 71a and the second ground electrode 74b of the second circuit block 71b are opposed to each other. Then, the flexible substrates 70 are folded together.

  Next, as shown in FIG. 8 (e), the first circuit block 71 a and the second circuit block 71 b of the folded flexible substrate 70 are pressurized with a uniform pressure so as to be spaced apart by a spacer 75, and crimped. To do. Then, the conductor 15 and the resin layer described below (provided if necessary) are completely cured by heat treatment. At this time, the treatment is performed, for example, at a heating temperature of 200 ° C. and under a pressure of about 0.1 MPa. As a result, the first ground electrode 74a of the first circuit block 71a and the second ground electrode 74b of the second circuit block 71b are connected by the conductor 15, and between the predetermined conductive vias 16, the conductor 15 is also connected. Connect with.

  Then, by folding the flexible substrate 70 and making the first circuit block 71a and the second circuit block 71b face each other at a predetermined interval, a space portion 72 having a predetermined interval is formed around the signal electrode 73. A multilayer circuit board is produced.

  When the conductor 15 is formed, a resin layer is applied to the portion of the first circuit block 71a and the second circuit block 71b where conduction is not necessary, for example, with an insulating sheet or an insulating adhesive. It may be formed. In this case, the spacer 75 is not necessarily provided. This prevents a short circuit due to the flow of the conductor 15 when the first circuit block 71a and the second circuit block 71b are folded, and improves the adhesion strength between the first circuit block 71a and the second circuit block 71b. A great effect can be obtained as a reinforcing member for the space 72.

  According to Embodiment 5 of the present invention, flexible substrates can be folded and overlapped and formed in a lump, so that a multilayer circuit substrate having a high-frequency transmission line can be manufactured at low cost by reducing the number of steps.

(Embodiment 6)
FIG. 9 is a cross-sectional view for explaining the outline of the multilayer circuit board according to Embodiment 6 of the present invention. In FIG. 9, the same components as those in FIG.

  In FIG. 9, a multilayer circuit board, for example, a flexible board 90 on which conductive vias 16 are formed, forms a predetermined wiring circuit layer 11, and at least a first circuit block 91a, a second circuit block 91b, and a third circuit board. Circuit block 91c. The first circuit block 91a includes at least a first signal electrode 93a and a pair of first ground electrodes 94a provided in parallel to the left and right of the first signal electrode 93a.

  The second circuit block 91b includes a pair of second ground electrodes 94b that are folded and face the first ground electrode 94a at a position facing the first ground electrode 94a. Further, on the opposite surface, a second signal electrode 93b and a pair of third ground electrodes 94c provided in parallel to the left and right of the second signal electrode 93b are provided.

  The third circuit block 91c has a pair of fourth ground electrodes 94d at a position facing at least the third ground electrode 94c on the surface facing the third ground electrode 94c.

  The flexible substrate 90 includes a first ground electrode 94a of the first circuit block 91a, a second ground electrode 94b of the second circuit block 91b, a third ground electrode 94c of the second circuit block 91b, and The conductor 15 is connected to the fourth ground electrode 94d of the third circuit block 91c. At this time, the flexible substrate 90 is bent as necessary so that the folded first circuit block 91a, the second circuit block 91b, and the third circuit block 91c are held at a constant interval. A spacer 95 is provided.

  The flexible substrate 90 is double-folded while being held at a constant interval by the spacer 95, and at least the first ground electrode 94a, the second ground electrode 94b, the third ground electrode 94c, and the fourth ground electrode are folded. 94d is electrically connected via the conductor 15. As a result, a multilayer circuit board having a high-frequency transmission line in which a space 92 is formed around each of the first signal electrode 93a and the second signal electrode 93b is obtained.

  According to the sixth embodiment of the present invention, the same effects as those of the first embodiment can be obtained, and a plurality of flexible substrates can be folded and formed in a lump so that a thin and inexpensive multilayer circuit board having three or more layers can be easily formed. Can be realized.

  In the sixth embodiment, the flexible substrate is folded twice, and the configuration of the multilayer circuit substrate including three layers is described. However, the present invention is not limited to this. For example, a flexible circuit board on which a plurality of circuit blocks are further formed can be folded in multiple to form a multilayer circuit board having four or more layers.

  Below, the manufacturing method of the multilayer circuit board in Embodiment 6 of this invention is demonstrated, referring FIG. 9 using FIG.

  FIG. 10 is a process cross-sectional view for explaining one aspect of a method for manufacturing a multilayer circuit board in Embodiment 6 of the present invention. In FIG. 10, the same components as those in FIG.

  First, as shown in FIG. 10A, a first circuit block 91a and a second circuit block having the following configuration are provided in a predetermined region of the flexible substrate 90 in which the wiring circuit layer 11 and the conductive via 16 are formed. 91b and a third circuit block 91c are formed.

  In the first circuit block 91a, a first signal electrode 93a serving as a strip conductor and a pair of first ground electrodes 94a are wired in parallel to the left and right of the first signal electrode 93a, so-called coplanar lines. Form.

  In the second circuit block 91b, a pair of second ground electrodes 94b is formed on the surface of the second circuit block 91b that is folded and opposed to the first ground electrode 94a. Further, on the opposite surface, a second signal electrode 93b, which is a strip line, and a pair of third ground electrodes 94c on the left and right sides of the second signal electrode 93b are wired in parallel to form a coplanar line. .

  In the third circuit block 91c, a pair of fourth ground electrodes 94d is formed on a surface that is folded and faces the third ground electrode 94c at a position facing the third circuit block 91c.

  In addition, the said structure shows an example of a required component, It is not limited to this, You may comprise arbitrarily by various arrangement | positioning.

  Next, as shown in FIG. 10B, at least one of the first ground electrode 94a of the first circuit block 91a and the second ground electrode 94b of the second circuit block 91b, and the second circuit block. At least one of the third ground electrode 94c of 91b and the fourth ground electrode 94d of the third circuit block 91c, and the surface of the wiring circuit layer 11 such as a connection electrode connected to the conductive via 16, for example, a conductive adhesive The conductor 15 is formed by coating, transferring, or screen printing a predetermined amount.

  Next, as shown in FIG. 10 (c), for example, a columnar spacer 95 having a certain height is disposed at a predetermined position of the flexible substrate 90. Fold alternately and fold twice. As the spacer 95, an insulating resin, a metal on which an insulating film is formed, or the like can be used.

  Next, as shown in FIG. 10D, at least the first ground electrode 94a of the first circuit block 91a and the second ground electrode 94b of the second circuit block 91b of the folded flexible substrate 90, The third ground electrode 94c of the second circuit block 91b and the fourth ground electrode 94d of the third circuit block 91c are aligned and arranged to face each other.

  Then, as shown in FIG. 10E, for example, using a pressurizing device (not shown), the conductor 15 and a resin layer described below (provided if necessary) while maintaining a predetermined interval by the spacer 95. Is completely cured by applying pressure and heating. At this time, the treatment is performed, for example, at a heating temperature of 200 ° C. and under a pressure of about 0.1 MPa. Thus, the ground electrodes of each circuit block and the conductors 15 are connected, and the predetermined conductive vias 16 are also connected by the conductors 15. As a result, the first circuit block 91a, the second circuit block 91b, and the third circuit block 91c are integrated to face each other at a predetermined interval. Furthermore, a space portion 92 having a predetermined interval is formed around the first signal electrode 93a and the second signal electrode 93b, and a multilayer circuit board having a high-frequency transmission path composed of three layers is manufactured.

  In the case where the conductor 15 is formed, an insulating sheet, an insulating adhesive, or the like, for example, is provided in a portion where conduction is not required in the first circuit block 91a, the second circuit block 91b, and the third circuit block 91c. The resin layer may be formed by In this case, the spacer 95 is not necessarily provided. Thereby, the short circuit by the flow of the conductor 15 at the time of folding of the 1st circuit block 91a, the 2nd circuit block 91b, and the 3rd circuit block 91c can be prevented. Further, it is possible to improve the adhesive strength between the first circuit block 91a, the second circuit block 91b, and the third circuit block 91c, and to obtain a great effect as a space reinforcing member.

  In the above description, an example in which a flexible substrate is folded twice to form a multilayer circuit substrate having three layers has been described. However, the present invention is not limited to this. For example, a flexible circuit board on which a plurality of circuit blocks are formed may be bent multiple times by bending a plurality of circuit boards, thereby forming a multilayer circuit board structure having four or more layers.

  According to the sixth embodiment of the present invention, since a flexible substrate on which a plurality of circuit blocks are formed can be folded and overlapped and formed in a lump, a thin multilayer circuit substrate can be manufactured at low cost by reducing the number of steps. Can do.

(Embodiment 7)
FIG. 11 is a perspective view for explaining an example of a multilayer circuit board on which electronic components according to Embodiment 7 of the present invention are mounted. In FIG. 11, the same components as those in FIG.

  As shown in FIG. 11, the multilayer circuit board 100 according to the seventh embodiment is a semiconductor chip such as an IC on the outer surface of the first substrate 110a of the multilayer circuit board having three layers via the wiring circuit layer 111. 112, circuit components (not shown), etc. are connected to lead electrode terminals 115, and for example, high frequency electronic components such as ICs and circuit components are surface-mounted.

  Then, the lead electrode terminal 115 of the semiconductor chip 112 and the wiring circuit layer 111 are connected, and further connected to the signal electrode 113 through the conductive via 16 of the first substrate 110a. The signal electrode 113 is a space 117 formed by a first ground electrode 114 formed in parallel to the left and right of the signal electrode 113 and a second ground electrode 116 of the second substrate 110b connected via the conductor 15. Thus, a coplanar track is formed. With this coplanar line, data transmission with the semiconductor chip 112 and the like can be performed at high speed.

  According to the seventh embodiment of the present invention, the space portion is provided inside the multilayer circuit board, and the coplanar lines having the ground electrodes on the left and right of the signal electrode are formed in the space portion, so that the high frequency transmission characteristics can be improved. it can. Furthermore, since a coplanar line can be formed inside, it becomes easy to design a circuit for high frequency, and an electronic component to be mounted can be arranged at an arbitrary position. Thus, a multilayer circuit board can be easily mounted on the electronic component. .

  In the seventh embodiment, the example in which the semiconductor chip is surface-mounted on the outermost substrate of the multilayer circuit board has been described. However, the present invention is not limited to this. For example, a semiconductor chip is embedded in a recess in a substrate on which a multilayer circuit board is stacked by a method such as partially forming a recess in the thickness direction of the substrate, and a signal electrode or a ground electrode is inserted through the semiconductor chip and a conductive via. You may connect with. In the case of a resin substrate such as a flexible substrate, a semiconductor chip or the like may be directly embedded in the resin substrate, and for example, a bump of the semiconductor chip exposed on the surface of the resin substrate may be directly connected to the signal electrode.

  As a result, the connection distance between the electronic component and the high-frequency transmission line such as a coplanar line is shortened, so that the high-frequency transmission characteristics can be further improved, and a small and high-density multilayer circuit board can be obtained.

  In each of the above embodiments, the multilayer circuit board is described as an example in which the coplanar line having the ground electrodes on the left and right sides of the signal electrode is formed on at least one of the board surfaces forming the space portion. I can't. For example, a multi-strip line configuration can be implemented similarly by forming a signal electrode on one substrate surface in which a space is formed and forming a ground electrode on the other surface of the substrate to form a microstrip line configuration. A circuit board is obtained.

  In each of the above embodiments, the ground electrodes formed on the left and right sides of the signal electrode have been described. However, the ground electrodes do not necessarily have to have the same potential, and high-frequency transmission can be similarly performed. .

  In each of the above embodiments, each substrate has been described as having a conductive via structure filled with a conductive paste, but it goes without saying that a through-hole structure may be used.

  Hereinafter, the multilayer circuit board of FIG. 1 will be described as an example based on examples.

  As shown in FIG. 1, a first substrate 10a in a multilayer circuit substrate having a two-layer structure includes at least a signal electrode 13 and a pair of first ground electrodes 14a provided in parallel to the left and right of the signal electrode 13. The film thickness t of the coplanar line was formed at about 12 μm. At this time, the line width s of the signal electrode 13 was about 100 μm, and the interval w between the signal electrode 13 and the first ground electrode 14a was about 100 μm. Here, each electrode was formed by screen printing of a conductive paste containing 85% by weight of silver conductive filler.

  Further, the distance h between the first substrate 10a and the second substrate 10b arranged to face each other with the conductor 15 interposed therebetween was formed to be about 100 μm.

  Further, since the space 12 formed around the signal electrode 13 is air, the relative dielectric constant is 1.

  As a result of measuring the high-frequency transmission characteristics using the multilayer circuit board having the above-described configuration, the signal transmission waveform was not distorted or the phase was not inverted at a use frequency of 3 GHz.

  The multilayer circuit board and the manufacturing method thereof according to the present invention are useful in a technical field such as a portable electronic device in which a multilayer circuit board having a small size and a high density and excellent in high frequency transmission characteristics is required.

Sectional drawing explaining the outline of the multilayer circuit board in Embodiment 1 of this invention Sectional drawing for demonstrating one aspect | mode of the manufacturing method of the multilayer circuit board in Embodiment 1 of this invention Sectional drawing explaining the outline of the other Example of the multilayer circuit board in Embodiment 1 of this invention Sectional drawing explaining the outline of the multilayer circuit board in Embodiment 2 of this invention Sectional drawing explaining the outline of the multilayer circuit board in Embodiment 3 of this invention Sectional drawing explaining the outline of the multilayer circuit board in Embodiment 4 of this invention Sectional drawing explaining the outline of the multilayer circuit board in Embodiment 5 of this invention Process sectional drawing for demonstrating one aspect | mode of the manufacturing method of the multilayer circuit board in Embodiment 5 of this invention Sectional drawing explaining the outline of the multilayer circuit board in Embodiment 6 of this invention Process sectional drawing for demonstrating one aspect | mode of the manufacturing method of the multilayer circuit board in Embodiment 6 of this invention The perspective view explaining an example of the multilayer circuit board which mounted the electronic component in Embodiment 7 of this invention

Explanation of symbols

10a, 60a, 110a First substrate 10b, 60b, 110b Second substrate 11, 111 Wiring circuit layer 12, 32, 42, 52, 62, 72, 92, 117 Space 13, 33, 53, 73, 113 Signal electrode 14a, 64a, 74a, 94a, 114 First ground electrode 14b, 40, 64b, 74b, 94b, 116 Second ground electrode 15 Conductor 16 Conductive via 30 Third substrate 34a, 94c Third ground Electrode 34b, 94d Fourth ground electrode 53a, 63a, 93a First signal electrode 53b, 63b, 93b Second signal electrode 70, 90 Flexible substrate 71a, 91a First circuit block 71b, 91b Second circuit block 75, 95 Spacer 91c Third circuit block 100 Multi-layer circuit board 112 Semiconductor chip 115 Drawer Electrode terminal

Claims (11)

A first substrate having at least a signal electrode and a pair of first ground electrodes provided in parallel to the left and right of the signal electrode;
And at least a second substrate having a pair of second ground electrodes provided at positions facing the first ground electrode,
A conductor connecting the first ground electrode of the first substrate and the second ground electrode of the second substrate, and at least a space portion provided by the conductor around the signal electrode; A multilayer circuit board characterized by the above. The second ground electrode is formed to have a width between a pair of the first ground electrodes facing each other, and the second ground electrode is formed on the second substrate facing the signal electrode. The multilayer circuit board according to claim 1, wherein: 3. The multilayer circuit board according to claim 1, wherein the signal electrode includes a pair of a first signal electrode and a second signal electrode formed in parallel. A first substrate having at least a first signal electrode and a pair of first ground electrodes provided in parallel to the left and right of the first signal electrode;
And at least a second signal electrode provided at a position facing the first signal electrode and the first ground electrode and a second substrate having a pair of second ground electrodes,
A conductor connecting the first ground electrode of the first substrate and the second ground electrode of the second substrate, and the periphery of the opposing first signal electrode and second signal electrode A multilayer circuit board, wherein at least a space is provided by the conductor. The multilayer circuit board according to any one of claims 1 to 4, wherein the first substrate and the second substrate are flexible substrates. 6. The multilayer circuit board according to claim 1, wherein at least one of the first board and the second board is a double-sided circuit board having a conductive via. A first circuit block having at least a signal electrode and a pair of first ground electrodes provided in parallel to the left and right of the signal electrode, and a pair provided at a position facing at least the first ground electrode A second circuit block having a second ground electrode, and a flexible substrate provided with at least
The flexible substrate has a conductor formed on at least one of the first ground electrode of the first circuit block and the second ground electrode of the second circuit block;
The flexible substrate is folded to connect the first ground electrode and the second ground electrode via the conductor, and at least a space is provided around the signal electrode by the conductor. A featured multilayer circuit board. A first circuit block having at least a first signal electrode and a pair of first ground electrodes provided in parallel to the left and right of the first signal electrode; and the first ground electrode on one surface; A pair of second ground electrodes provided at opposing positions, and a second signal electrode on the other surface and a pair of third ground electrodes provided in parallel to the left and right of the second signal electrode A flexible circuit board provided with at least a second circuit block having at least a third circuit block having a pair of fourth ground electrodes provided at positions opposed to the third ground electrode,
The flexible substrate includes at least one of the first ground electrode of the first circuit block and the second ground electrode of the second circuit block, and the third ground electrode of the second circuit block. And a conductor formed on at least one of the fourth ground electrodes of the third circuit block,
The flexible substrate is folded to connect the first ground electrode, the second ground electrode, the third ground electrode, and the fourth ground electrode through the conductors, respectively. A multilayer circuit board, wherein at least a space portion is provided by the conductor around the signal electrode and the second signal electrode. Forming at least a signal electrode and a pair of first ground electrodes provided in parallel to the left and right of the signal electrode on the first substrate;
Forming a pair of second ground electrodes on the second substrate at least at a position facing the first ground electrode;
Connecting the first ground electrode of the first substrate and the second ground electrode of the second substrate with a conductor to form a space around the signal electrode;
A method for producing a multilayer circuit board, comprising: A first circuit block having at least a signal electrode and a pair of first ground electrodes provided in parallel to the left and right of the signal electrode, and a pair provided at a position facing at least the first ground electrode Forming a second circuit block having a second ground electrode on at least a flexible substrate;
Forming a conductor on at least one of the first ground electrode of the first circuit block and the second ground electrode of the second circuit block of the flexible substrate;
Folding the flexible substrate to connect the first ground electrode and the second ground electrode via the conductor, and at least forming a space around the signal electrode;
A method for producing a multilayer circuit board, comprising: A first circuit block having at least a first signal electrode and a pair of first ground electrodes provided in parallel to the left and right of the first signal electrode; and the first ground electrode on one surface; A pair of second ground electrodes provided at opposing positions, and a second signal electrode on the other surface and a pair of third ground electrodes provided in parallel to the left and right of the second signal electrode Forming a second circuit block having a second circuit block and a third circuit block having a pair of fourth ground electrodes provided at a position facing at least the third ground electrode on at least a flexible substrate;
At least one of the first ground electrode of the first circuit block and the second ground electrode of the second circuit block; and the third ground electrode of the second circuit block. And forming a conductor on at least one of the fourth ground electrodes of the third circuit block;
The flexible substrate is folded to connect the first ground electrode, the second ground electrode, the third ground electrode, and the fourth ground electrode through the conductors, respectively. Forming at least a space around the signal electrode and the second signal electrode;
A method for producing a multilayer circuit board, comprising:

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