WO2014034672A1

WO2014034672A1 - Transmission circuit structure body

Info

Publication number: WO2014034672A1
Application number: PCT/JP2013/072889
Authority: WO
Inventors: 大塚　寛治; 秋山　豊; 千寿上田; 典史笹岡; 貴史越智; 大野　正人
Original assignee: 学校法人明星学苑; ニッポン高度紙工業株式会社
Priority date: 2012-08-31
Filing date: 2013-08-27
Publication date: 2014-03-06
Also published as: TW201414368A

Abstract

Provided is a transmission circuit structure body whereby, without requiring a low dielectric-constant, low dielectric-tangent resin such as a fluorine resin or a liquid-crystal polymer, signal transmission without high-frequency component loss even in frequency regions beyond 5GHz is possible. A transmission circuit structure body is configured wherein a signal line is formed in contact with one surface of an interlaminar insulation layer, and a ground layer is formed in contact with another surface of the interlaminar insulation layer, said ground layer comprising a conductive microparticle dispersed film wherein conductive microparticles are dispersed in an organic material.

Description

Specification

Title of invention: Transmission circuit structure

Technical field

[0001] The present invention relates to a transmission circuit structure having a signal line and a ground pattern.

Background art

[0002] In recent years, electronic devices equipped with IC chips, such as computers and mobile communication devices, have been increasing in speed and mounting density. With higher mounting density, it is becoming increasingly important to ensure signal quality called signal integrity by designing wiring to prevent signal reflection and distortion, and crosstalk between wires.

[0003] However, the frequency of the high-speed interface that has been developed exceeds 5 GHz, and in order to use such a high frequency, it is necessary to shorten the rise time of the signal compared to the conventional method. Yes, as the rise time is shortened, the high-frequency component of the signal appears significantly. Therefore, in order to reduce the loss of high-frequency components, it is essential to use copper foil with a low surface roughness and use a resin with a low dielectric constant and dielectric loss tangent.

[0004] In the transmission circuit as described above, as typical examples of a substrate material having good high-frequency characteristics, a fluororesin substrate (see, for example, Patent Document 1 and Patent Document 2) and a liquid crystal polymer substrate (for example, Patent Document) However, in addition to being more expensive than general-purpose glass epoxies, there are also problems in processing such as low adhesion and low adhesive strength with copper foil. In addition, in materials such as fluororesin substrates and liquid crystal polymer substrates, the surface roughness is small to reduce loss due to the skin effect when used for high-speed signal transmission exceeding 5 GHz as described above. Circuit design such as adopting copper foil and thickening the resin layer to reduce dielectric loss is essential.

Prior art documents

Patent Literature Patent Document 1: Japanese Patent Laid-Open No. 2 0 5 _ 7 6 6 8 ([0 0 0 2]) Patent Document 2: Japanese Patent Laid-Open No. 2 0 _ 2 6 6 5 2

Patent Document 3: Japanese Patent Laid-Open No. 2 0 0 6-1 2 8 3 2 6 ([0 0 1 0]) Summary of the Invention

Problems to be solved by the invention

[0006] Typical examples of substrate materials with good high-frequency characteristics include fluororesin substrates and liquid crystal polymer substrates, but they are more expensive than general-purpose glass epoxies. There is also a problem in terms of processing such as low adhesive strength with the foil. For high-speed signal transmission exceeding 5 GHz, use copper foil with a small surface roughness to reduce loss due to the skin effect, and thicken the resin layer to reduce dielectric loss. Circuit design is essential.

[0007] In order to solve the above-described problems, in the present invention, a high-frequency wave can be obtained even in a frequency region exceeding 5 GHz without using a low dielectric constant, low dielectric loss tangent resin such as a fluororesin or a liquid crystal polymer. Means for solving a problem with the aim of providing a transmission circuit structure capable of transmitting a signal without loss of components, and thereby achieving high-speed operation of an electronic device

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 conductive fine particles are dispersed in the organic material in contact with the other main surface of the insulating layer. A ground layer made of a conductive fine particle dispersion film is formed.

[0009] According to the configuration of the transmission circuit structure of the present invention described above, the ground layer formed with the signal line and the insulating layer interposed therebetween is configured with the conductive fine particle dispersed film. The conduction in the conductive fine particle dispersed film is achieved by a talented junction at the contact portion between the conductive fine particles contained in the film. Even if the conductive fine particles do not contact each other, conduction can be achieved by the tunnel effect or the hot carrier effect. Even when the conductive fine particles are separated from each other, they can be conducted by many types of near-field effects such as a discharge effect due to electric field concentration and a shot effect if the material that disperses the conductive fine particles is a semiconductor. Is assisted. [0 0 1 0]

In addition, there is a voltage difference corresponding to the interval between the conductive fine particles between the conductive fine particles, and when this voltage difference changes, a displacement current according to the capacity between them flows. That is, capacitive coupling. This also assists in the transmission of electromagnetic energy.

The invention's effect

[0 0 1 1]

According to the transmission circuit structure of the present invention described above, the action of the conductive fine particle dispersion film constituting the ground layer allows the use of a resin having a low dielectric constant and a low dielectric loss tangent such as a fluororesin and a liquid crystal polymer. Signals can be transmitted without loss of high-frequency components even in the frequency range exceeding. For this reason, it is possible to prevent signal loss and signal error. As a result, by using a circuit board provided with this transmission circuit structure, it is possible to achieve high speed as well as high integration and miniaturization of electronic equipment.

Brief Description of Drawings

[0 0 1 2]

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

FIG. 2 is a cross-sectional view taken along line AA ′ in FIG.

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

FIG. 4 is a diagram showing an input signal of TDR measurement and a reflected signal.

FIG. 5 is a diagram showing the time lapse of the voltage of the signal returned to the input side obtained as a result of the TDR measurement.

[Fig. 6] A diagram showing the relationship between frequency and transmission loss, obtained as a result of S-parameter measurement.

FIG. 7 is a diagram showing the relationship between the passage of time and voltage obtained as a result of measuring the rise time of the propagation signal.

FIG. 8 is an enlarged view near the rising edge of the signal in FIG.

FIG. 9 is an eye pattern of a sample of the transmission circuit structure of the example.

FIG. 10 is an eye pattern of a sample of a transmission circuit structure of a comparative example.

FIG. 1 1 is a cross-sectional observation photograph of a sample of a transmission circuit structure of an example.

[FIG. 12] An image obtained by three-dimensionally synthesizing a cross-sectional photograph of a sample of the transmission circuit structure of the example. BEST MODE FOR CARRYING OUT THE INVENTION

[0 0 1 3]

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

[0 0 1 4]

1. First Embodiment>

'A schematic configuration diagram of the transmission circuit structure according to the first embodiment of the present invention is shown in FIGS. 1 and 2. FIG. Figure 1 shows a plan view, and Figure 2 shows a cross-sectional view at A- in Figure 1.

The transmission circuit structure shown in Figs. 1 and 2 is in contact with the upper surface of the interlayer insulating layer 15

Included by citation (Rule 20.6) Line 1 1 (S) and ground pattern 1 2 (G) are formed and in contact with the lower surface of the interlayer insulating layer 15 and containing conductive fine particles in resin ■ Ground consisting of conductive fine particle dispersion film dispersed Layer 17 is formed.

An insulating layer 1 4 is formed on the signal line 1 1 and the ground pattern 1 2. Under the ground layer 17, an insulating layer 16 is formed.

In this 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 an integrated insulating layer 13. Yes.

Hereinafter, the details of these components 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.

[001 5] The signal line 1 1 is formed by patterning a thin film obtained by planarly extending a bulk material into a linear shape. The material constituting the signal line 1 1 is not limited as long as the material has good conductivity. For example, copper (C u), aluminum (AI), gold (A u), silver ( A g) and alloys containing these as the main components are used as the metal foil. Here, for example, a signal line 11 made of copper foil is provided.

[001 6] Two ground patterns 1 2 are formed on both sides of the signal line 1 1 and apart from the signal line 1 1. That is, the signal line 11 and the ground pattern 12 form the same configuration as a so-called coplanar line.

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

Similar to the signal line 11, the ground pattern 12 is formed by linearly patterning a thin film obtained by extending a bulk material in a plane. The material constituting the ground pattern 12 is not limited as long as the material has good conductivity. For example, copper (C u), aluminum (AI), gold (A u), silver (A g) and alloys containing these as the main components are used as the metal foil. Here, for example, a ground pattern 12 made of copper foil is provided. I will do it.

[0017] The ground layer 17 may be configured as a single-layer structure of a conductive fine particle dispersed film as illustrated, or a laminated structure of a conductive fine particle dispersed film and a conductive material such as a copper foil, for example. It may be configured as. When the ground layer has a laminated structure, the conductive fine particle dispersion film is arranged on the signal line and insulating layer side.

Here, the conductive fine particles used for the conductive fine particle dispersed film are configured using a material having good conductivity. Such conductive fine particles are composed of gold (Au), silver (Ag), copper (Cu), aluminum (AI), nickel (N ί), or graphite. These materials may be used alone or as an alloy based on these materials. Furthermore, conductive fine particles may be formed by mixing a plurality of types of particles made of these materials, or particles made of other conductive materials.

These conductive fine particles are used in the form of flakes (flakes), spheres, and long particles, and a plurality of types may be used in combination.

[0019] When graphite is used as the conductive fine particles, disc-shaped graphite particles having a and b surfaces as bottom surfaces are used. These graphite particles are particles in which graphene is laminated in the ab plane direction. Here, the free electron density of copper is 1.3 X 10 ²³ / cm ³ , but the electron mobility is only 5.1 X 10 ¹ cm ² / V-s. On the other hand, the a and b planes of the graph item have a free electron density of only 10 ¹³ / cm 3, but the electron mobility is as high as 1 X 10 ⁴ cm 2 / V ■ s and the mean free path is long. . For this reason, the electrical conductivity of the a and b surfaces of the graph items is said to be better than copper. The c-axis direction of the graph item has a large resistance. For this reason, it is desirable to use thin crystalline particles of darafen as conductive fine particles. The shape of conductive fine particles is, for example, 50 Aim or less in the long side direction, 1 O tm or less in the short side direction, and 5 tm in thickness. It is assumed that the following particle shapes are mainly included, and those with spherical shapes of less than l O m, elliptical spheres, and isotropically deformed particles are included. The

[0020] The conductive fine particle-dispersed film is formed by dispersing the conductive fine particles as described above in an organic material and then curing.

As the organic material for dispersing conductive fine particles as described above, a material capable of dispersing conductive fine particles is used. As such an organic material, for example, an epoxy resin, a polyimide resin, a polyimide resin, and a BT (bismaleide 卜 lyazine) resin can be selected as appropriate from commonly used organic insulating materials. Can be used.

[0021] The conductive fine particle-dispersed film preferably has an electric resistivity of 5 times or more that of the bulk material of the material constituting the conductive fine particles, more preferably 1 It is about 0 0 0 times. The electrical resistivity of such a conductive fine particle dispersed film can be increased by reducing the film thickness.

The conductive fine particle-dispersed film is formed by using a pace rod in which conductive fine particles are dispersed in an organic material diluted with a solvent. For example, it is formed by using a commercially available silver pace candy. The silver paste is obtained by dispersing silver particles in a solution obtained by diluting, for example, an epoxy resin precursor and a curing agent as an organic material, and other additives as necessary. By forming a thin film using such a silver paste and curing the organic material in this thin film, the conductive particles

The conductive state is maintained by approaching or partially contacting each other up to a distance where the interaction occurs, and a conductive fine particle dispersed film is obtained.

In such a conductive fine particle dispersed film, the solvent may be removed from the film in the process of curing or drying the organic material (for example, epoxy resin or polyamide imide resin). is there.

Further, the conductive fine particle dispersed film may contain additives such as a dispersant and a cosolvent for improving the dispersibility of the conductive fine particles.

[0023] Further, for example, the thickness of the signal line 11 and the ground pattern 12 made of copper foil

, And the thickness of the ground layer 17 composed of the conductive fine particle dispersed film is determined by the current capacity handled by the transmission circuit structure. If the transmission circuit structure is used for an electronic circuit, the thickness of the signal line 1 1 and the ground pattern 12 is preferably several m to several h.

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

The insulating layer 13 is preferably made of an organic material that can be diluted in the same solvent as the organic material that forms the conductive fine particle dispersed film. In this case, the precursors before drying or curing the respective organic materials constituting the insulating layer 13 and the conductive fine particle dispersed film can be diluted or dissolved in the same solvent. It ’s fine.

For such an insulating layer 13, for example, a material similar to the organic material constituting the conductive fine particle dispersed film is used. For example, when a conductive fine particle dispersion film in which silver particles are dispersed in an epoxy resin is provided, an epoxy resin, a polyimide resin, a polyimide resin or the like is used for the insulating layer 13. These resins and their precursors can be diluted or dissolved in solvents such as alcohols, ketones and esters. Other specific examples of such solvents that can be diluted or dissolved include N-methylpyrrolidone, alpha-pyrolactone, diglyme, cyclopentanone, and ethyl benzoate.

Note that in the insulating layer 13 made of such an organic material, the solvent may be removed in the process of hardening or drying the organic material.

In addition, the insulating layer 13 is used by adjusting to an appropriate molecular structure and dielectric constant according to the performance required for the transmission circuit structure. For example, when an insulating layer 13 made of polyamide resin is used, the dielectric structure can be improved by improving the molecular structure of polyamide or by dispersing high dielectric constant powder or low dielectric constant powder in the resin. The rate is adjusted.

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

If this transmission circuit structure is used for an electronic circuit, the thickness of the insulating layer 1 3 is set to several m to 200 m. If the transmission circuit structure is used for a transmission cable,

The film thickness of 13 is set to several m to several mm.

In this 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. However, these insulating layers 14, It is possible to use different insulating materials for 1 5 and 1 6.

Further, the ground pattern 12 formed with the signal line 11 interposed therebetween may be omitted. In this case, the signal line and the ground layer sandwich the interlayer insulating layer.

[0028] The transmission circuit structure having the above-described configuration is used as a circuit board or a transmission cable. In this case, for example, it may be used by being connected to the substrate extraction electrode, or may be used as a configuration embedded in the connector. Furthermore, this transmission circuit may have the ground layer covered with an inorganic insulating film or an organic insulating film.

[0029] (Transmission circuit manufacturing method)

The transmission circuit structure as described above can be manufactured, for example, as described below.

[0030] First, for example, a copper foil is prepared, and an organic insulating film is formed thereon as an insulating layer. At this time, a solution obtained by diluting or dissolving the organic material with a solvent is applied onto the copper foil.

Then, an insulating layer is obtained by performing a drying process.

Next, the copper foil is patterned to form a signal line 11 and a ground pattern 12 made of the copper foil.

A conductive fine particle dispersion film is formed on the insulating layer. At this time, a paste in which conductive fine particles are dispersed in a solution in which an organic material is diluted is applied onto the insulating layer. For diluting the organic material, it is preferable to use the same solvent in which 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.

[0032] Next, a step of curing or drying the organic material of the conductive fine particle dispersed film is performed. Yeah. In this step, the insulating layer is cured simultaneously. Here, it is important to cure the organic material without deforming the conductive fine particles in the conductive fine particle dispersion film and to maintain the dispersed state of the conductive fine particles in the film. Therefore, here, the 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 dispersed film and the organic material constituting the insulating layer are cured or dried. Further, when the organic material constituting the conductive fine particle dispersed film and the organic material constituting the insulating layer are photocurable resins, curing by light irradiation may be performed. The conductive fine particle dispersion film thus obtained serves as a ground layer.

If the ground layer is configured as a laminated structure of a conductive fine particle dispersed film and a conductive material such as copper foil, the upper part of the conductive fine particle dispersed film produced as described above is used. A conductive material such as copper foil is laminated on the substrate. Thus, 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 side is obtained.

As described above, the transmission circuit structure is completed. In the transmission circuit structure thus obtained, the ground layer 17 is configured using a conductive fine particle dispersed film in which conductive fine particles are dispersed in an organic material.

Example

[0034] (Experiment 1)

As an example, a transmission circuit structure (S 1) having the structure shown in FIGS. 1 and 2 and applying the configuration of the present invention was manufactured.

As a comparative example, a transmission circuit structure (C 1) to which a conventional configuration was applied, in which the structure shown in the sectional view of FIG. 2 was changed to the structure shown in the sectional view of FIG. In the structure shown in FIG. 3, a ground layer 52 made of copper foil and a connection part 51 made of a conductor layer are formed instead of the conductive fine particle dispersed film shown in FIG.

The configuration of the ground layer in the transmission circuit structure of each sample in Experiment 1 is as shown in Table 1 below.

[0036] [table 1]

[0037] Next, a manufacturing procedure of each transmission circuit structure will be described.

First, prepare a support that has a peelable adhesive layer with a weaker adhesive strength than ordinary resin adhesives on an aluminum foil with a thickness of about 1 OO m. On the adhesive layer of this support, A Cu foil having a thickness of 18 Aim was formed.

Thereafter, the Cu foil is patterned by etching. As a result, a signal line 11 and a ground pattern 12 made of Cu foil are formed.

At this time, in each sample, the length L of the transmission circuit structure was 20 Omm, and the width W of the transmission circuit structure was 20 mm. In addition, the width of the signal line 11 is 100 m, and the distance between the signal line 1 1 and the daland pattern 12 is 550 m.

[0038] Next, on the surface of the Cu foil, a solvent-soluble polyamide-imide (PA I) using N-methyl-2-pyrrolidone as a solvent was applied, and this was dried to form an interlayer made of PAI. Insulating layer 15 is formed. The film thickness of the interlayer insulating layer 15 is 15 to 20 ^ m. Next, a connection hole is formed in the interlayer insulating layer 15. In sample C1, the connection hole 5 1 is formed by filling the connection hole with a mesh or a conductive pace filling hole.

Next, in sample S1, by applying a conductive fine particle dispersion base and drying it, a ground layer 17 made of a conductive fine particle dispersion film is formed inside the connection hole and on the surface of the interlayer insulating film. Form. At this time, as shown in Table 1 above, in Sample S1, the shape and material of the conductive fine particles are flaky A 9 (major axis 6.2 m, content 85 wt%). The film thickness of the ground layer 17 made of the conductive fine particle dispersed film is 5 to 1 Om. As the solvent for the conductive fine particle dispersion base, N_methyl_2_pyrrolidone similar to P A I constituting the interlayer insulating layer 15 is used.

On the other hand, in the sample C 1, a copper (Cu) foil (film thickness: 18 Aim) is bonded to the interlayer insulating layer 15 and the connection portion 51 by thermocompression bonding to form the ground layer 52.

[0040] After that, on each of the ground layers 17 and 52, similarly to the interlayer insulating layer 15 in each sample, a solvent-soluble polyamideimide (PA I) using N-methyl-2-pyrrolidone as a solvent. ) Is applied and dried to form an insulating layer 16 made of PAI. The film thickness of the insulating layer 16 is about 10 Aim.

[0041] Next, the support on the back surfaces of the signal line 11 and the ground pattern 12 is removed.

Subsequently, on the back surface of the signal line 1 1 and the ground pattern 1 2, as in the insulating layer 1 4 in each sample, a solvent-soluble polyamideimide (PA) using N _methyl _2 pyrrolidone as a solvent I) is applied and dried to form an insulating layer 14 made of PAI. The thickness of the insulating layer 14 is about 1 O ^ m.

[0042] Through the above steps, a transmission circuit structure of each sample was obtained.

The dielectric constant ε of the interlayer insulating layer 15 after completion of drying, measured by a cavity resonator perturbation method, and a measurement frequency of 1 GHz was 2.9.

[0043] The characteristics of the transmission circuit structures of the fabricated samples were measured and evaluated.

[0044] (1) TDR (Time Domain Ref Lectmetory) measurement In the samples of the transmission circuit structures of the example and the comparative example, one end of the sample was used as the input side. Then, a GS probe (CP690-01) was connected to this input side, and the GS probe was further connected to an Ag i Lent digital oscilloscope 86100C. As shown in Fig. 4, a step voltage of 20 mV was input as an input signal S in to the input side of the sample of the transmission circuit structure from the digital talent siroscope through the GS probe.

The signal is returned at the other end 19 of the transmission circuit structure, that is, at the end of the line, so that the signal is returned. By detecting this reflected signal S ref, the characteristic impedance Z of the circuit of the transmission circuit structure. (The inherent value of the line) and the time 2 t _pd required for the electromagnetic energy to travel back and forth on the transmission line.

Electromagnetically, the velocity V of the electromagnetic wave propagating through the transmission line is derived from the dielectric constant ε of the resin of the interlayer insulating layer 15 and the following equation (1).

[0045] [Equation 1]

ν- _ω

-.

[0046] Fig. 5 shows the time lapse of the voltage of the signal returned to the input side as a measurement result.

As can be seen from FIG. 5, the propagation time of the example was about 21% shorter than that of the comparative example.

[0047] When the transmission circuit structure sample of the example was repeatedly manufactured and measured, the same result was obtained.

[0048] By the way, in the case of the sample of the example, considering the equation (1), the relative permittivity of the metal fine particle dispersion film becomes I ε J <1, and the electromagnetic wave propagating in the metal fine particle dispersion film is considered. In this case, the speed is faster than the speed of light. However, since this is a calculated value based on Equation (1) derived from Maxwell's electromagnetic equation to the last, it is assumed that it does not fall within Maxwell's electromagnetic equation in the case of a metal particle dispersion film. Since there is no phenomenon faster than the speed of light in physics, the physics that reasonably explains this is that the relative permittivity related to the polarization of the interlayer insulator is effectively lowered, that is, it is difficult to polarize. Can be interpreted as it can.

[0049] (2) One S-parameter measurement

In the sample of the transmission circuit structure of the example and the comparative example, S parameter measurement (measurement of loss for each frequency component) was performed.

In the samples of the transmission circuit structures of the example and the comparative example, one end of the sample was used as the input side, and the other end of the sample was used as the output side. Then, Cascade Microtech Z Probe 040 K3N GSG 500 was connected to each of the input side and output side, and through this prop, it was connected to an Nent vector network analyzer N5230A. Then, we input signals at different frequencies on the input side, and examined the amount of transmission loss on the output side for each frequency.

[0050] Fig. 6 shows the relationship between frequency and transmission loss (dB) as a measurement result.

As shown in FIG. 6, the example has less high-frequency component loss than the comparative example. In particular, at 20 GHz, there was a marked difference in the magnitude of the loss.

[0051] (3) Measurement of propagation signal rise time

Assuming actual digital signal transmission, the rise time of the propagation signal was measured in the transmission circuit structure samples of the example and the comparative example.

In the samples of the transmission circuit structures of Examples and 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. Cascade Microtech Z Probe 040 K3N GSG 500 was connected to each of the input and output sides. Furthermore, a pulse pattern generator 8133A made by HewLett Packard was connected to the input side via this probe, and a digital talent shiroscope 86100A made by Ag Lent was connected to the output side.

[0052] With the connection as described above, a clock signal was input from the input side. The clock signal voltage was 1 V, the frequency was 1 MHz, and the pulse rise time Tr was 36 to 44 ps.

The output of the signal obtained on the output side was observed with a digital oscilloscope.

Figure 7 shows the relationship between time and voltage as a measurement result. Figure 7 Figure 8 shows an enlarged view around the rising edge of the signal. Figure 8 shows the time elapsed between 20% and 80% of the voltage, assuming 0.6 1 6V as 100%.

As shown in FIGS. 7 and 8, the sample of the example has a shorter rise time of the propagation signal than the sample of the comparative example. From FIG. 8, the elapsed time of 20% → 80% is 1 19 p s in the example and 1 63 p s in the comparative example.

That is, in the sample of the example, the rise time of the propagation signal is shortened by about 27% compared to the comparative example.

[0053] (4) Evaluation of transmission characteristics of high-speed digital signals

Assuming actual high-speed digital signal transmission, eye patterns were measured on samples of the transmission circuit structures of the examples and comparative examples. In the eye pattern measurement, the signal wiring width of the example is 1 000 tm and the width of the signal wiring of the comparative example is 60 m in order to eliminate the influence on the measurement data due to the characteristic impedance mismatch. Measurements were carried out on objects. The size of the ground pattern on both sides is adjusted in response to changes in the signal wiring, and other sizes and external dimensions remain the same, and their characteristic impedances are in the range of 50 ± 10Ω. .

In the samples of the transmission circuit structures of the example and the comparative example, one end of the sample was used as the input side, and the other end of the sample was used as the output side. A GS Prop (CP690-01, 6 GHz) was connected to each of the input and output sides. Furthermore, the Anritsu pulse pattern generator MP1761B was connected to the input side through this program, and the Agi Lent digital talent Shiroscope 8686A was connected to the output side.

[0054] With the connection as described above, a random signal having an amplitude of 1 V, a signal transmission rate of 10 G bps, and 23 stages of PRBS was input from the input side. The signal obtained on the output side was observed with a digital oscilloscope.

As the measurement results, the eye patterns of the observed examples and comparative examples are shown in FIG. 9 and FIG. As shown in FIGS. 9 and 10, the sample of the example can confirm the opening of the central portion, whereas the sample of the comparative example shows the opening at all. Absent. In other words, it can be said that the sample of the example has greatly improved the transmission characteristics of the high-speed digital signal compared to the comparative example.

From the above, it can be seen that the sample of the example has the characteristics that the propagation speed of the signal is fast, the rise of the propagation signal is short, and the transmission characteristic of the high-speed digital signal is good.

[0056] Subsequently, the conductive fine particle dispersion film of the sample of the example was observed with an electron microscope.

Figures 11 and 12 show photographs. Fig. 11 is a photograph of the cross section taken from the side, and Fig. 12 is a three-dimensional composite image of 50 cross-sections taken in steps of about 1 m as in Fig. 11.

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

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

For example, as shown in the cross section of Fig. 11, the effective ground coupling of signal line 1 1 in Fig. 2 is much stronger in daland layer 1 7 than daland pattern 1 2. That is, since the spatial distance is narrow, a microstrip line structure in which the ground pattern 12 is omitted can be adopted.

Explanation of symbols

[0058] 1 1 Signal line, 1 2 Ground pattern, 1 3, 1 4, 1 6 Insulating layer, 1 5 Inter-layer insulating layer, 1 7, 5 2 Ground layer, 5 1 Connection

Claims

The scope of the claims

A signal line is formed in contact with one main surface of the insulating layer,

A transmission circuit structure in which a ground layer made of a conductive fine particle dispersion film in which conductive fine particles are dispersed in an organic material is formed in contact with the other main surface of the insulating layer.

The conductive fine particles are composed of gold, silver, copper, aluminum, nickel, or graph eye 卜

The transmission circuit structure according to claim 1.

The transmission circuit structure according to claim 1, wherein the insulating layer is configured using an organic material that can be diluted or dissolved in the same solvent as the organic material that forms the conductive fine particle dispersion film.

The conductive fine particle dispersion film is sandwiched between organic insulating films made of an organic material that can be diluted or dissolved in the same solvent as the organic material constituting the fine particle dispersion film.

The transmission circuit structure according to claim 1.

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 spaced apart from the signal line with the signal line interposed therebetween.