TW201414368A - Transmission circuit structure body - Google Patents

Abstract

The invention provides a transmission circuit structure body, in which a resin such as a fluororesin or a liquid crystal polymer having a low dielectric constant and a low dielectric loss tangent is unnecessary. Even if in a region having a frequency over 5 GHz, a signal can be transmitted in which no high frequency components are lost. The transmission circuit structure body is composed of the following: a signal wire, formed by contacting with a main surface of an interlayer insulating layer, and a ground layer, including a conductive fine particle dispersion film, formed by contacting with another main surface of the interlayer insulating layer. The conductive fine particle dispersion film is formed by dispersing conductive fine particles in an organic material.

Description

Transmission circuit structure

The present invention relates to a transmission circuit structure including a signal line and a ground pattern.

In recent years, an electronic device equipped with an integrated circuit (IC) chip such as a computer or a mobile communication device has been developed to have a higher speed and a higher mounting density. A wiring design that prevents reflection or distortion of signals due to high mounting density, crosstalk generated between wirings, and the like, and ensures signal quality called signal integrity becomes more and more important.

However, the frequency of the developed high-speed interface becomes a value exceeding 5 GHz. When the high frequency is used, the rise time of the signal must be made shorter than before, and the high-frequency component of the signal is made shorter by the rise time. Significantly revealed. Therefore, in order to reduce the loss of high-frequency components, it is necessary to select a material such as a copper foil having a small surface roughness or a resin having a low dielectric constant and a dielectric loss tangent.

In the above-mentioned transmission circuit, a fluororesin substrate (see, for example, Patent Document 1, Patent Document 2) or a liquid crystal polymer substrate (see, for example, Patent Document 3), etc., may be mentioned as a representative of a substrate material having a high-frequency characteristic. But if it's with versatile glass In addition to the high price, the epoxy resin has a problem of a plating surface and a low adhesion strength to a copper foil. Further, in materials such as a fluororesin substrate or a liquid crystal polymer substrate, when used for high-speed signal transmission exceeding 5 GHz as described above, in order to reduce loss due to a skin effect, it is necessary to adopt A copper foil having a small surface roughness or a circuit design in which a resin layer is thickened to reduce dielectric loss.

[Previous Technical Literature]

[Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2005-7668 ([0002])

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2002-76652

[Patent Document 3] Japanese Patent Laid-Open Publication No. 2006-128326 ([0010])

A typical example of the substrate material having high-frequency characteristics is a fluororesin substrate or a liquid crystal polymer substrate. However, compared with a general-purpose glass epoxy resin, in addition to being expensive, plating adhesion and copper are also available. The problem of the finished surface of the foil is low on the machined surface. In addition, in order to reduce the loss due to the skin effect when used for high-speed signal transmission exceeding 5 GHz, it is necessary to use a copper foil having a small surface roughness or to thicken the resin layer in order to reduce dielectric loss. Circuit design.

In order to solve the above problems, an object of the present invention is to provide a transmission circuit structure, thereby realizing high-speed operation of an electronic device which does not use a low dielectric constant or a low dielectric such as a fluororesin or a liquid crystal polymer. Resin with electrical loss tangent, no loss of high frequency component even in the frequency region exceeding 5 GHz The signal is transmitted.

In the transmission circuit structure of the present invention, a signal line is formed in contact with one main surface of the insulating layer, and a ground layer including a conductive fine particle dispersion film is formed in contact with the other main surface of the insulating layer. The conductive fine particle dispersion film is obtained by dispersing conductive fine particles in an organic material.

According to the configuration of the transmission circuit structure of the present invention described above, the ground layer formed by sandwiching the insulating layer with the signal line includes the conductive fine particle dispersion film. The conduction of the conductive fine particle-dispersed film is achieved by ohmic bonding of the contact portions of the conductive fine particles contained in the film. Further, even if the conductive fine particles are not in contact with each other, conduction can be achieved by a tunnel effect or a hot carrier effect. Further, even when the conductive fine particles are separated from each other, the conduction can be assisted by the discharge effect caused by the concentration of the electric field, or if the substance in which the conductive fine particles are dispersed is a semiconductor, the Schottky can also be used. A variety of near-field effects such as the Schottky effect are used to aid conduction.

Further, a voltage difference corresponding to the interval between the conductive fine particles exists between the respective conductive fine particles, and a displacement current corresponding to the capacitance between the conductive particles flows when the voltage difference changes. That is, it becomes capacitive coupling. This capacitive coupling also assists in the transmission of electromagnetic energy.

According to the transmission circuit structure of the present invention, by the action of the conductive fine particle dispersion film constituting the ground layer, a resin having a low dielectric constant or a low dielectric loss tangent such as a fluororesin or a liquid crystal polymer is not used, even if In the frequency region exceeding 5 GHz, signals can also be transmitted without loss of high frequency components. Therefore, loss of signal or signal error can be prevented. As a result, by using the transmission circuit structure The circuit board of the body can achieve high integration, miniaturization and high speed of electronic equipment.

11, 11 (S) ‧ ‧ signal line

12, 12 (G) ‧ ‧ grounding pattern

13, 14, 16‧‧ insulation

15‧‧‧Interlayer insulation

17‧‧‧ Grounding layer

19‧‧‧Transport the other end of the circuit structure

51‧‧‧Connecting Department

52(G)‧‧‧ Grounding layer

L‧‧‧Transfer circuit structure length

W‧‧‧Transfer circuit structure width

Sref‧‧·reflected signal

Sin‧‧‧ input signal

1 is a schematic configuration view (plan view) of a transmission circuit structure according to a first embodiment of the present invention.

Figure 2 is a cross-sectional view taken along line A-A' of Figure 1 .

3 is a schematic cross-sectional view showing a sample of a transmission circuit structure of a comparative example.

4 is a view showing an input signal and a reflected signal measured by Time Domain Reflectometry (TDR).

Fig. 5 is a view showing the passage of time of the voltage of the signal returned to the input side obtained as a result of the measurement by the time domain reflectometry.

Fig. 6 is a graph showing the relationship between the frequency obtained as a result of the S parameter measurement and the transmission loss.

Fig. 7 is a view showing a relationship between time passage and voltage obtained as a result of measurement of a rise time of a transmission signal.

Fig. 8 is an enlarged view of the vicinity of the rise of the signal of Fig. 7.

Fig. 9 is a view showing an eye pattern of a sample of the transmission circuit structure of the embodiment.

Fig. 10 is an eyelet pattern of a sample of a transfer circuit structure of a comparative example.

Fig. 11 is a cross-sectional observation photograph of a sample of the transmission circuit structure of the embodiment.

FIG. 12 is an image obtained by three-dimensionally combining cross-sectional photographs of samples of the transmission circuit structure of the embodiment.

Embodiments of the present invention will be described below based on the drawings.

<1. First Embodiment>

FIG. 1 and FIG. 2 are schematic diagrams showing a configuration of a transmission circuit structure according to a first embodiment of the present invention. 1 is a plan view, and FIG. 2 is a cross-sectional view taken along line AA' of FIG. 1.

In the transfer circuit structure shown in FIGS. 1 to 2, the signal line 11 (S) and the ground pattern 12 (G) are formed in contact with the upper surface of the interlayer insulating layer 15, and are in contact with the lower surface of the interlayer insulating layer 15. On the other hand, a ground layer 17 containing a conductive fine particle-dispersed film in which conductive fine particles are contained and dispersed in a resin is formed.

An insulating layer 14 is formed on the signal line 11 and the ground pattern 12. An insulating layer 16 is formed under the ground layer 17.

In the present embodiment, as shown in FIG. 2, the insulating layer 14, the interlayer insulating layer 15, and the insulating layer 16 are formed of the same insulating material, and become the integrated insulating layer 13.

Hereinafter, the details of the constituent elements will be described in the order of the signal line 11, the ground pattern 12, the insulating layer 13, and the ground layer 17 including the conductive fine particle dispersed film.

The signal line 11 is formed by patterning a film in which a bulk material is planarly stretched into a line shape. The material constituting the signal line 11 is not limited as long as it is a material having good conductivity. For example, copper (Cu), aluminum (Al), gold (Au), silver (Ag), and an alloy containing these as a main component are used. As a metal foil. Here, for example, a signal line 11 containing a copper foil is provided.

The ground pattern 12 is formed by sandwiching the signal line 11 and being separated from the signal line 11. That is, the same configuration as the so-called coplanar line is formed by the signal line 11 and the ground pattern 12.

The same potential, for example, a ground potential, is applied to the two ground patterns 12.

Similarly to the signal line 11, the ground pattern 12 is formed by patterning a film in which a block-shaped material is planarly stretched into a line shape. The material constituting the ground pattern 12 is not limited as long as it is a material having good conductivity, and for example, copper (Cu), aluminum (Al), gold (Au), silver (Ag), and an alloy containing the same as a main component are used. As a metal foil. Here, for example, a ground pattern 12 including a copper foil is provided.

The ground layer 17 may have a single layer structure as a conductive fine particle dispersion film as shown in the drawing, or may be configured as a laminated structure of a conductive fine particle dispersed film and a conductive material such as a copper foil. When the ground layer is a laminated structure, the conductive fine particle dispersed film is disposed on the signal line and the insulating layer side.

Here, the conductive fine particles used for the conductive fine particle dispersion film are formed using a material having good conductivity. The conductive fine particles are made of gold (Au), silver (Ag), copper (Cu), aluminum (Al), nickel (Ni), or graphite. These materials can be used as a monomer or as an alloy containing the materials as a main component. Further, a plurality of types of particles containing the materials or particles further containing other conductive materials may be mixed to form conductive fine particles.

These conductive fine particles are used in the form of flakes (flakes), spheres, and long grains, and may be used in combination of various shapes.

In the case where graphite is used as the conductive fine particles, disk-shaped graphite particles having the a-plane and the b-plane as the bottom surface are used. This graphite particle is a particle obtained by laminating graphene in the a-plane direction and the b-plane direction. Here, the free electron density of copper is 1.3 × 10 ²³ /cm ³ , but the electron mobility is only 5.1 × 10 ¹ cm ² /V. s. On the other hand, the free electron density of the a-plane and the b-plane of graphite is only 10 ¹³ /cm ³ , but the electron mobility is higher at 1 × 10 ⁴ cm ² /V. s, and the average free length is long. Therefore, it is considered that the conductivity of the a-plane and the b-plane of graphite is better than that of copper. Further, the c-axis direction of graphite has a large electric resistance. Therefore, it is preferable to use crystalline particles thin in graphene as the conductive fine particles.

In addition, the shape of the conductive fine particles is, for example, a particle shape having a longitudinal direction of 50 μm or less, a short-side direction of 10 μm or less, and a thickness of 5 μm or less, and a spherical shape, an ellipsoidal shape, and an isotropic form of 10 μm or less. Particle shape.

The conductive fine particle dispersion film is obtained by dispersing the conductive fine particles as described above in an organic material and then curing them.

The organic material in which the conductive fine particles are dispersed as described above is a material that can disperse the conductive fine particles. As the organic material, for example, an epoxy resin, a polyimide resin, a polyamide-imide resin, or a bimaleimine triazine (Bisma1eimide Triazine, BT) can be used. An organic insulating material which is generally used, such as a resin, is suitably selected and used.

Further, the electrical resistivity of the conductive fine particle-dispersed film is preferably 5 times or more, more preferably about 1,000 times, the electrical resistivity of the bulk material constituting the conductive fine particles. The electrical resistivity of the conductive fine particle dispersed film is improved by making the film thickness thin.

The conductive fine particle dispersion film is formed by using a slurry in which conductive fine particles are dispersed in an organic material diluted with a solvent. For example, it is generally formed using a commercially available silver paste. The silver paste is, for example, a solution in which silver particles are dispersed in a solvent, a precursor of an epoxy resin as an organic material, a curing agent, and other additives as needed. Made in liquid. The silver paste is used to form a film, and the organic material in the film is cured, whereby the conductive particles are brought close to each other to a distance at which the interaction occurs, or are locally contacted to maintain an on state, thereby obtaining a conductive fine particle-dispersed film.

Further, in the conductive fine particle dispersion film, there is a case where the solvent is removed from the film during the process of curing or drying the organic material (for example, an epoxy resin or a polyimide).

Further, the conductive fine particle-dispersed film may contain an additive such as a dispersing agent or a solubilizing agent for improving the dispersibility of the conductive fine particles.

Further, for example, the thickness of the signal line 11 and the ground pattern 12 including the copper foil, and the thickness of the ground layer 17 including the conductive fine particle dispersion film are determined according to the current capacitance processed by the transfer circuit structure.

When the transmission circuit structure is used for an electronic circuit, the thickness of the signal line 11 and the ground pattern 12 is preferably several μm to several tens of μm.

Further, if the transmission circuit structure is a cable for transmission, the thickness of the signal line 11 and the ground pattern 12 is from several μm to several tens of mm.

The insulating layer 13 is preferably made of an organic material which can be diluted in the same solvent as the organic material constituting the conductive fine particle dispersed film. In this case, the precursor before or after curing the respective organic materials constituting the insulating layer 13 and the conductive fine particle-dispersed film may be diluted or dissolved with the same solvent.

As the insulating layer 13, for example, the same material as the organic material constituting the conductive fine particle dispersed film is used. For example, in the case where a conductive fine particle dispersion film in which silver particles are dispersed in an epoxy resin is provided, an epoxy resin, a polyimide resin, or a polyimide resin is used for the insulating layer 13. Wait. The resin or its precursor may be diluted or dissolved with a solvent such as an alcohol, a ketone or an ester. As other specific examples of the solvent which can dilute or dissolve the above resin or its precursor, there are N-methylpyrrolidone, γ-butyrolactone, diethylene glycol II. Dimlyme, cyclopentanone, ethyl benzoate, and the like.

Further, in the insulating layer 13 containing the organic material, there is also a case where the solvent is removed during the hardening or drying of the organic material.

Further, the insulating layer 13 is used in accordance with the performance required for the transmission circuit structure, and is adjusted to an appropriate molecular structure or dielectric constant. For example, in the case of using the insulating layer 13 containing a polyamidoximine resin, the molecular structure of the polyamidoximine is improved, or a powder having a high dielectric constant or a powder having a low dielectric constant is dispersed. The dielectric constant is adjusted in the resin.

The thickness of the insulating layer 13 is set so that a predetermined characteristic impedance can be obtained in the ground pattern 12 and the ground layer 17.

When the transmission circuit structure is used for an electronic circuit, the thickness of the insulating layer 13 is set to several μm to 200 μm.

Further, when the transmission circuit structure is a cable for transmission, the thickness of the insulating layer 13 is set to several μm to several mm.

Further, in the present embodiment, the case where the insulating layer 14, the interlayer insulating layer 15, and the insulating layer 16 are formed of the same insulating material has been described, but the insulating layer 14, the interlayer insulating layer 15, and the insulating layer may be used. Layer 16 uses a different insulating material.

Alternatively, the ground pattern 12 formed by sandwiching the signal line 11 may be omitted. In this case, the interlayer insulating layer is interposed between the signal line and the ground layer.

The transmission circuit structure constructed as described above is used as a circuit substrate or a transmission power cable. In this case, for example, it may be connected to the substrate take-out electrode to be used or used as a structure embedded in a connector. Further, the transfer circuit may cover the ground layer with an inorganic insulating film or an organic insulating film.

(Manufacturing method of transmission circuit)

The transfer circuit structure as described above can be manufactured, for example, in the following manner.

First, for example, a copper foil is prepared, and an organic insulating film is formed as an insulating layer on the upper portion of the copper foil. At this time, a solution obtained by diluting or dissolving an organic material with a solvent is applied onto a copper foil, followed by drying treatment, thereby obtaining an insulating layer.

Then, the copper foil is patterned to form the signal line 11 including the copper foil and the ground pattern 12.

A conductive fine particle dispersion film is formed on the insulating layer. At this time, a slurry in which conductive fine particles are dispersed in a solution obtained by diluting an organic material is used, and the slurry is applied onto an insulating layer. In the dilution of the organic material, it is preferred to use the same solvent as the organic material constituting the insulating layer is diluted or dissolved.

Thereafter, the coated film is dried to obtain a conductive fine particle-dispersed film.

Then, a step of curing or drying the organic material of the conductive fine particle-dispersed film is performed. In this step, the insulating layer is simultaneously hardened. Here, it is important that the organic fine material is hardened without deforming the conductive fine particles in the conductive fine particle-dispersed film, and the dispersed state of the conductive fine particles in the film is maintained. Therefore, here, heat treatment is performed at a temperature lower than the melting point of the conductive fine particles in the conductive fine particle dispersion film. Thereby, the organic material constituting the conductive fine particle dispersion film and the organic material constituting the insulating layer are cured or dried. In addition, in the conductive fine particle dispersion film When the organic material and the organic material constituting the insulating layer are photocurable resins, they may be cured by light irradiation. The conductive fine particle-dispersed film thus obtained serves as a ground layer.

In the case where the ground layer is formed of a laminated structure of a conductive fine particle-dispersed film and a conductive material such as a copper foil, conductivity is deposited on the upper portion of the conductive fine particle-dispersed film produced as described above, such as copper foil. material. Thereby, a ground layer having a laminated structure of the conductive fine particle-dispersed film on the insulating layer side and the conductive material on the upper portion thereof was obtained.

The transfer circuit structure is completed in the above manner. The transmission circuit structure thus obtained constitutes the ground layer 17 by using a conductive fine particle dispersion film in which conductive fine particles are dispersed in an organic material.

[Examples]

(Experiment 1)

As an embodiment, a transmission circuit structure (S1) to which the present invention is applied is manufactured by using the structure shown in Figs. 1 to 2 .

In addition, as a comparative example, a transmission circuit structure (C1) to which the structure shown in the cross-sectional view of FIG. 2 is changed to the structure shown in the cross-sectional view of FIG. 3 is applied.

The structure shown in FIG. 3 forms a ground layer 52 using a copper foil and a connecting portion 51 using a conductor layer instead of the conductive fine particle dispersed film of FIG.

The configuration of the ground layer in the transfer circuit structure of each sample of the above experiment 1 is as shown in Table 1 below.

Next, the manufacturing steps of the respective transmission circuit structures will be described.

First, a support having a peelable adhesive layer having a lower adhesive force than a usual resin-based adhesive is formed on an aluminum foil having a thickness of about 100 μm, and a Cu foil having a thickness of 18 μm is formed on the adhesive layer of the support.

Thereafter, the Cu foil is patterned by etching. Thereby, the signal line 11 including the Cu foil and the ground pattern 12 are formed.

At this time, in each sample, the length L of the transmission circuit structure was set to 200 mm, and the width W of the transmission circuit structure was set to 20 mm. Further, the width of the signal line 11 was set to 100 μm, and the interval between the signal line 11 and the ground pattern 12 was set to 550 μm.

Then, a solvent-soluble polyamine-imide (PAI) coated with N-methyl-2-pyrrolidone as a solvent is coated on the surface of the Cu foil by using the polyamidamine The imine is dried to form an interlayer insulating layer 15 containing PAI. The film thickness of the interlayer insulating layer 15 is set to 15 μm to 20 μm.

Then, a connection hole is formed in the interlayer insulating layer 15. In sample C1, The connection portion 51 is formed by filling a connection hole with a conductive paste for plating or filling.

Next, in the sample S1, the conductive fine particle-dispersed slurry is applied and dried to form a ground layer 17 containing a conductive fine particle-dispersed film on the inside of the connection hole and the surface of the interlayer insulating film. At this time, as shown in the above Table 1, the shape and material of the conductive fine particles in the sample S1 were platelet-shaped Ag (long diameter: 6.2 μm, content: 85 wt% (% by weight)). The thickness of the ground layer 17 including the conductive fine particle dispersion film is set to 5 to 10 μm. As the solvent of the conductive fine particle-dispersed slurry, the same N-methyl-2-pyrrolidone as the PAI constituting the interlayer insulating layer 15 was used.

On the other hand, in the sample C1, a copper (Cu) foil (film thickness: 18 μm) was bonded to the interlayer insulating layer 15 and the connection portion 51 by thermocompression bonding to form the ground layer 52.

Thereafter, a solvent-soluble polyamine having N-methyl-2-pyrrolidone as a solvent is applied to the upper portion of the ground layer 17 and the ground layer 52 in the same manner as the interlayer insulating layer 15 of each sample. The quinone imine (PAI), and the polyamidoximine is dried to form an insulating layer 16 comprising PAI. The thickness of the insulating layer 16 is set to about 10 μm.

Next, the support body existing on the back surface of the signal line 11 and the ground pattern 12 is removed.

Then, on the back surface of the signal line 11 and the ground pattern 12, a solvent-soluble polyamidofluorene containing N-methyl-2-pyrrolidone as a solvent is applied in the same manner as the insulating layer 14 of each sample. An amine (PAI), and the polyamidoximine is dried to form an insulating layer 14 comprising PAI. The thickness of the insulating layer 14 is set to about 10 μm.

Through the above steps, the transfer circuit structure of each sample was obtained.

Further, the relative dielectric constant ε _{r of the} interlayer insulating layer 15 after completion of the drying was measured by a cavity resonator perturbation method at a measurement frequency of 1 GHz, and was 2.9.

Regarding the transfer circuit structure of each of the prepared samples, characteristics were performed. Determination and evaluation.

(1) Time Domain Reflectometry

In the samples of the transfer circuit structures of the examples and the comparative examples, one end of the sample was used as the input side. Furthermore, a ground-signal probe (CP690-01) is connected to the input side, and the ground-signal probe is connected to an Agilent digital oscilloscope 86100C.

From the digital oscilloscope, as a grounding-signal probe, as shown in FIG. 4, a step voltage of 200 mV is input to the input side of the sample of the transmission circuit structure as an input signal Sin.

The signal is reflected and returned at the other end 19 of the transmission circuit structure, that is, the terminal of the line. Therefore, by detecting the reflected signal Sref, the characteristic impedance Z ₀ of the circuit of the transmission circuit structure (the inherent value of the line) is known. ), and the time required for the electromagnetic energy to travel back and forth in the transmission line 2t _pd .

In terms of electromagnetics, the velocity V of the electromagnetic wave transmitted on the transmission line is derived by the dielectric constant ε of the resin of the interlayer insulating layer 15 and the following formula (1).

As a result of the measurement, the time of returning the voltage of the signal to the input side is shown in FIG.

As can be seen from Fig. 5, the transmission time was shortened by about 21% in the embodiment relative to the comparative example.

Further, the samples of the transfer circuit structure of the examples were repeatedly produced and measured, and the same results were obtained.

Further, in the case of the sample of the embodiment, the relative dielectric constant ∣ ε _r ∣ <1 of the metal fine particle dispersed film is considered from the viewpoint of the formula (1), and the electromagnetic wave transmitted in the metal fine particle dispersed film is assumed to be considered. In the case of speed, it becomes faster than the speed of light. However, in the final analysis, the calculated value obtained by the equation (1) derived from Maxwell's electromagnetic equation is used. Therefore, in the case of the metal fine particle dispersed film, it is assumed that it is not suitable for the electromagnetic of Maxwell. equation. Physically, there is no faster phenomenon than light, so in the physical explanation of this phenomenon, it can be explained that the relative dielectric constant associated with the polarization of the interlayer insulator becomes practically lower, that is, becomes difficult. Perform polarization.

(2) S parameter determination

In the samples of the transfer circuit structures of the examples and the comparative examples, S-parameter measurement (measurement of the magnitude of loss with respect to each frequency component) was performed.

In the samples of the transfer circuit structures of the examples and the comparative examples, one end of the sample was used as the input side, and the other end of the sample was used as the output side. Furthermore, the Z Probe 040 K3N GSG 500 manufactured by Cascade Microtech is connected to the input side and the output side, and the Z Probe 040 K3N GSG 500 is connected to the vector network analyzer manufactured by Agilent via the probe ( Vector network analyzer)N5230A.

Further, the frequency is changed and a signal is input to the input side, and the amount of transmission loss on the output side is investigated for each frequency.

As a result of the measurement, the relationship between the frequency and the transmission loss (dB) is shown in Fig. 6.

As shown in Fig. 6, the embodiment has less loss of high frequency components than the comparative example. Especially at 20 GHz, significant differences can be observed in the magnitude of the loss.

(3) Determination of the rise time of the transmitted signal

Assuming that the actual digital signal is transmitted, the rise time of the transmission signal is measured in the samples of the transmission circuit structure of the embodiment and the comparative example.

In the samples of the transfer circuit structures of the examples and the comparative examples, one end of the sample was used as the input side, and the other end of the sample was used as the output side. Further, a Z Probe 040 K3N GSG 500 manufactured by Kent Precision Technology is connected to the input side and the output side. Further, a pulse pattern generator 8133A manufactured by Hewlett Packard was connected to the input side via the probe, and a digital oscilloscope 86100A manufactured by Agilent was connected to the output side.

In the state of being connected as described above, a clock signal is input from the input side. The voltage of the clock signal is set to 1 V, the frequency is set to 1 MHz, and the rise time Tr of the pulse is set to 36 ps to 44 ps.

Moreover, the output of the signal obtained on the output side is observed using a digital oscilloscope.

As a result of the measurement, the relationship between time passage and voltage is shown in FIG. In addition, an enlarged view of the vicinity of the rise of the signal of FIG. 7 is shown in FIG. In Fig. 8, 0.616 V is set to 100% to indicate the elapsed time between its voltage of 20% and 80%.

As shown in FIGS. 7 and 8, the sample of the example has a shorter rise time of the transmission signal than the sample of the comparative example. According to Fig. 8, the elapsed time of 20% → 80% is 119 ps in the embodiment, and 163 ps in the comparative example.

That is, in the sample of the example, the rise time of the transmission signal was shortened by about 27% with respect to the comparative example.

(4) Evaluation of transmission characteristics of high-speed digital signals

The eye hole pattern was measured in the samples of the transmission circuit structures of the examples and the comparative examples, assuming the transmission of the actual high-speed digital signal. In the measurement of the eye pattern, in order to The influence on the measurement data due to the characteristic impedance mismatch was discharged, and the measurement was performed for the case where the width of the signal wiring of the example was 1000 μm and the width of the signal wiring of the comparative example was 60 μm. The size of the ground pattern on both sides is adjusted with respect to the change of the signal wiring, and the other dimensions and the outer dimensions are kept the same size, and the respective characteristic impedances are in the range of 50 ± 10 Ω.

In the samples of the transfer circuit structures of the examples and the comparative examples, one end of the sample was used as the input side, and the other end of the sample was used as the output side. Further, a ground-signal probe (CP690-01, 6 GHz) is connected to the input side and the output side, respectively. Further, a pulse waveform generator MP1761B manufactured by Anritsu is connected to the input side via the probe, and a digital oscilloscope 86100A manufactured by Agilent is connected to the output side.

In the state connected as described above, a random signal having an amplitude of 1 V, a signal transmission rate of 10 Gbps, and a pseudo-random binary sequence (PRBS) of 23 segments is input from the input side. Moreover, the signal obtained on the output side is observed using a digital oscilloscope.

As a result of the measurement, the observed eye pattern of the examples and the comparative examples are shown in Figs. 9 and 10, respectively. As shown in Fig. 9 and Fig. 10, the opening of the center portion was clearly observed in the sample of the example, and the opening portion was not seen at all in the sample of the comparative example. That is, it can be considered that the sample of the example has a large improvement in the transmission characteristics of the high-speed digital signal with respect to the comparative example.

From the above, it is understood that the sample of the embodiment has a feature that the signal transmission speed is fast, the rise time of the transmission signal is short, and the transmission characteristics of the high-speed digital signal are good.

Then, the conductivity of the sample of the example was observed by an electron microscope. Particle dispersion film. A photograph of the conductive fine particle dispersed film is shown in Figs. 11 and 12 . Fig. 11 is a photograph obtained by photographing a cross section from the side, and Fig. 12 is an image obtained by photographing 50 cross sections at intervals of about 1 μm and performing three-dimensional synthesis in the same manner as Fig. 11 .

As shown in FIG. 11 and FIG. 12, a conductive fine particle dispersion film in which conductive fine particles are dispersed and dispersed is formed.

The present invention is not limited to the above-described embodiments or examples, and various other configurations can be obtained without departing from the gist of the invention.

For example, as shown in the cross-section of FIG. 11, in terms of the effective grounding coupling of the signal line 11 of FIG. 2, the ground layer 17 is much stronger than the ground pattern 12, that is, the spatial distance is narrow, so that it can also be used. The microstrip line structure of the ground pattern 12 is omitted.

11(S)‧‧‧ signal line

12(G)‧‧‧ Grounding pattern

13, 14, 16‧‧ insulation

15‧‧‧Interlayer insulation

17‧‧‧ Grounding layer

Claims (5)

A transmission circuit structure in which a signal line is formed in contact with a main surface of an insulating layer, and a ground layer including a conductive fine particle dispersion film is formed in contact with the other main surface of the insulating layer, and the conductive fine particles are formed The dispersion film is obtained by dispersing conductive fine particles in an organic material. The transmission circuit structure according to claim 1, wherein the conductive fine particles are made of gold, silver, copper, aluminum, nickel, or graphite. The transmission circuit structure according to claim 1, wherein the insulating layer is made of an organic material which can be diluted or dissolved in the same solvent as the organic material constituting the conductive fine particle dispersion film. The transfer circuit structure according to claim 1, wherein the conductive fine particle dispersion film is sandwiched by an organic insulating film which is diluted in the same solvent as the organic material constituting the fine particle dispersed film. Or composed of dissolved organic materials. The transmission circuit structure according to claim 1, wherein a ground pattern is formed in contact with the one main surface of the insulating layer, and the ground pattern is disposed apart from the signal line with the signal line interposed therebetween.