JP2017073593A - High frequency line and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a high frequency line having a desired high frequency characteristics even if substrate thickness and signal line width fluctuate depending on manufacturing tolerance.SOLUTION: A groove 104 is formed on a second substrate 102 above an inner layer signal line 103 along the inner layer signal line 103. The width and the depth of the groove 104 are formed in a state in which a desired characteristic impedance of the inner layer signal line 103 is obtained.SELECTED DRAWING: Figure 1A

Description

  The present invention relates to an IMSL-structured high-frequency line capable of obtaining a desired characteristic impedance and a method for manufacturing the same.

  In recent years, as mounting density has increased, studies on flip chip mounting in which substrates and packages are connected in the vertical direction have been actively conducted. Flip-chip mounting has advantages such as GND (grand) enhancement during high frequency applications, improved mounting density, improved isolation, and impedance reduction avoidance in coplanar connection.

  As such a mounting form, for example, an IMSL (Inverted Micro Strip Line) configuration as shown in FIG. 8 in which the configuration of a microstrip line (MSL: Micro Strip Line) of a secondary substrate is inverted has been proposed (non-conversion). Patent Document 1). In this IMSL configuration, an inner layer signal line 402 is provided immediately below the uppermost dielectric substrate 401 of the plurality of stacked dielectric substrates 401, and a ground conductive layer 403 is provided on the uppermost dielectric substrate 401. .

  In the IMSL configuration, similar to the MSL configuration, the characteristic impedance is determined by parameters such as the dielectric constant of the dielectric substrate 401, the thickness H of the dielectric substrate 401, and the width W0 of the inner layer signal line 402. For example, when the dielectric substrate 401 is made of alumina ceramic, the dielectric constant is 9.8 (dielectric loss tangent tan σ = 0.006), and the thickness is 0.254 mm, the width of the inner layer signal line 402 changes. The reflection characteristics change as shown in FIG.

  9A shows the reflection characteristics when the inner layer signal line 402 has a width of 0.16 mm, and FIG. 9B shows the reflection characteristics when the inner layer signal line 402 has a width of 0.145 mm. The reflection characteristics when the inner layer signal line 402 has a width of 0.175 mm are shown. The dielectric substrate 401 has a structure in which six layers are laminated, and there is no ground conductive layer between the layers, and simulation was performed by a finite element method (HFSS).

S. Yamaguchi et al., "An inverted microstrip line IC structure for ultra high-speed applications", IEEE MTT-S International Microwave Symposium Digest, vol.3, pp.1643-1646, 1995.

  As described above, the characteristic impedance is determined by parameters such as the dielectric constant, the substrate thickness, and the signal line width. Therefore, in the high frequency line of the IMSL configuration, the line width is determined when the substrate thickness is determined. There were restrictions. In addition, in the high frequency line having the IMSL configuration, when the substrate thickness or the signal line width fluctuates due to manufacturing tolerances, there is a problem that a desired high frequency characteristic cannot be obtained because the characteristic impedance changes.

  The present invention has been made to solve the above-described problems, so that a high-frequency line having a desired high-frequency characteristic can be formed even if the substrate thickness or signal line width varies due to manufacturing tolerances or the like. The purpose is to do.

  The method for manufacturing a high-frequency line according to the present invention includes a first step of forming an inner signal line on a first substrate, and a second step of laminating a second substrate on the surface of the first substrate on which the inner signal line is formed. And a third step of forming a groove portion along the inner layer signal line on the second substrate above the inner layer signal line, and a ground conductor constituting the inner layer signal line and the microstrip line on the upper surface of the second substrate on which the groove portion is formed. A fourth step of forming a layer, and the width and depth of the groove are formed in a state where desired characteristic impedance of the inner layer signal line can be obtained.

  In the high frequency line manufacturing method, the groove may be formed immediately above the inner signal line. In this case, the ground conductive layer may be formed in a region other than the groove.

  In the method for manufacturing a high-frequency line, two grooves arranged with the inner-layer signal line sandwiched in a plan view may be formed.

  A high-frequency line according to the present invention, a first substrate, a second substrate stacked on the first substrate, an inner layer signal line disposed between the first substrate and the second substrate, and an upper layer signal line A groove formed on the second substrate along the inner layer signal line, and a ground conductive layer formed on the upper surface of the second substrate on which the groove is formed and constituting the inner layer signal line and the microstrip line, and the width of the groove And the depth is such that the desired characteristic impedance of the inner layer signal line can be obtained.

  In the high frequency line, the groove may be formed immediately above the inner signal line. In this case, the ground conductive layer may be formed in a region other than the groove.

  The high-frequency line may be provided with two groove portions arranged with the inner-layer signal line in plan view.

  As described above, according to the present invention, since the groove portion is formed along the inner layer signal line on the second substrate above the inner layer signal line, the substrate thickness and the signal line width vary due to manufacturing tolerances and the like. However, an excellent effect that a high-frequency line having a desired high-frequency characteristic can be formed can be obtained.

1A is a cross-sectional view showing a configuration of a high-frequency line according to Embodiment 1 of the present invention. FIG. 1B is a plan view showing the configuration of the high-frequency line according to Embodiment 1 of the present invention. FIG. 2A is a cross-sectional view showing the state of an intermediate step for explaining the method for manufacturing the high-frequency line in Embodiment 1 of the present invention. FIG. 2B is a cross-sectional view showing the state of an intermediate step for explaining the method for manufacturing the high-frequency line in Embodiment 1 of the present invention. FIG. 2C is a cross-sectional view showing a state of an intermediate step for explaining the method of manufacturing the high-frequency line in Embodiment 1 of the present invention. FIG. 3 is a characteristic diagram showing the reflection characteristics of the high-frequency line in the first embodiment. FIG. 4A is a cross-sectional view showing a configuration of a high-frequency line according to Embodiment 2 of the present invention. FIG. 4B is a plan view showing the configuration of the high-frequency line according to Embodiment 2 of the present invention. FIG. 5A is a cross-sectional view showing the state of an intermediate step for explaining the method of manufacturing the high-frequency line in Embodiment 2 of the present invention. FIG. 5B is a cross-sectional view showing the state of an intermediate step for explaining the method of manufacturing the high-frequency line in Embodiment 2 of the present invention. FIG. 6 is a characteristic diagram showing the reflection characteristics of the high-frequency line in the second embodiment. FIG. 7A is a cross-sectional view showing a configuration of a high-frequency line according to Embodiment 3 of the present invention. FIG. 7B is a plan view showing the configuration of the high-frequency line according to Embodiment 3 of the present invention. FIG. 8 is a cross-sectional view showing a configuration of a high-frequency line having an IMSL configuration. FIG. 9 is a characteristic diagram showing reflection characteristics in a high frequency line having an IMSL configuration.

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

[Embodiment 1]
First, Embodiment 1 of the present invention will be described. FIG. 1A is a configuration diagram showing a configuration of a high-frequency line according to the first embodiment of the present invention. FIG. 1B is a plan view showing the configuration of the high-frequency line in the first embodiment of the present invention.

  The high-frequency line includes a first substrate 101, a second substrate 102 stacked on the first substrate 101, and an inner layer signal line 103 disposed between the first substrate 101 and the second substrate 102. Prepare. The first substrate 101 and the second substrate 102 are made of a dielectric.

  The high-frequency line is formed on the second substrate 102 above the inner layer signal line 103 along the inner layer signal line 103 and on the upper surface of the second substrate 102 on which the groove 104 is formed. A signal line 103 and a ground conductive layer 105 constituting a microstrip line are provided.

  In the first embodiment, the groove 104 is formed immediately above the inner layer signal line 103. A ground conductive layer 105 is formed on the upper surface of the second substrate 102 including the inside of the groove 104. Note that a dielectric substrate (not shown) may be formed below the first substrate 101. For example, four dielectric substrates are laminated below the first substrate 101, and six dielectric substrates in total are laminated. When a ground conductive layer is also provided below the inner layer signal line 103, the distance between the ground conductive layer and the inner layer signal line 103 is larger than the distance between the inner layer signal line 103 and the ground conductive layer 105.

  In the configuration described above, the width and depth of the groove 104 are characterized in that the desired characteristic impedance of the inner layer signal line 103 is obtained. Since the groove 104 is provided on the upper surface of the second substrate 102 on which the ground conductive layer 105 is formed, the groove 104 having a predetermined depth and width is formed after the second substrate 102 is formed on the inner signal line 103. By forming, the electric field coupling strength between the inner signal line 103 and the ground conductive layer 105 can be adjusted later. Thus, according to the first embodiment, the characteristic impedance of the inner layer signal line 103 can be controlled after the second substrate 102 is formed.

  Next, the manufacturing method of the high frequency line in Embodiment 1 of this invention is demonstrated using FIG. 2A-FIG. 2C. 2A to 2C are cross-sectional views illustrating a state of an intermediate process for explaining the method of manufacturing the high-frequency line in the first embodiment of the present invention.

  First, as shown in FIG. 2A, the inner layer signal line 103 is formed on the first substrate 101 (first step). For example, a groove is formed in the line formation region of the first substrate 101 made of alumina ceramic. Next, copper (Cu) is deposited by a well-known plating method to form a Cu film. Thereafter, the Cu film is etched back by a chemical mechanical polishing method or the like, and the groove formed with the surface of the first substrate 101 in a flat state is filled with Cu, so that it is made of Cu. The inner signal line 103 is formed.

  Next, as shown in FIG. 2B, the second substrate 102 is laminated on the surface of the first substrate 101 on which the inner signal line 103 is formed (second step). For example, the bonding surface (back surface) of the second substrate 102 is bonded to the bonding surface (upper surface) of the first substrate 101 on which the inner layer signal line 103 is formed by a known bonding technique.

  Next, as shown in FIG. 2C, a groove 104 is formed along the inner layer signal line 103 on the upper surface of the second substrate 102 above the inner layer signal line 103 (third step). In the first embodiment, the groove 104 is formed immediately above the inner signal line 103. In the formation of the groove 104, the width and depth of the groove 104 are formed so as to obtain a desired characteristic impedance of the inner signal line 103.

  Thereafter, if the ground conductive layer 105 is formed on the upper surface of the second substrate 102 in which the groove 104 is formed, the high frequency line shown in FIG. 1A can be obtained. The ground conductive layer 105 constitutes an inner layer signal line 103 and a microstrip line. For example, the ground conductive layer 105 made of Cu can be formed by depositing Cu by a plating method or the like.

  Next, the simulation result of the characteristic of the high frequency line in Embodiment 1 is demonstrated. The first substrate 101 and the second substrate 102 were made of alumina ceramic, and the plate thickness H was 0.254 mm. Further, the plate thickness H ′ of the second substrate 102 in the groove portion 104 was set to 0.21 mm. In this case, the depth of the groove 104 is 0.044 mm. Also, a four-layer dielectric substrate of the same material and the same thickness is provided below the first substrate 101, and a ground conductive layer is provided between the layers. Assume that there is no layer.

  For example, although the design value of the width of the inner layer signal line 103 is 0.16 mm, the case where the width becomes 0.145 mm as a result of manufacture will be considered. In this case, as shown in FIG. 3B, a desired reflection characteristic of 30 dB or less cannot be obtained. On the other hand, by forming the groove portion 104 having a depth of 0.044 mm and a width G of 0.32 mm on the second substrate 102 on the inner layer signal line 103 formed to have a width of 0.145 mm, FIG. As shown, a desired reflection characteristic of 30 dB or less can be obtained.

[Embodiment 2]
Next, a second embodiment of the present invention will be described. FIG. 4A is a block diagram showing the configuration of the high-frequency line in the first embodiment of the present invention. FIG. 4B is a plan view showing the configuration of the high-frequency line according to the first embodiment of the present invention.

  The high-frequency line includes a first substrate 101, a second substrate 102 stacked on the first substrate 101, and an inner layer signal line 103 disposed between the first substrate 101 and the second substrate 102. Prepare. The first substrate 101 and the second substrate 102 are made of a dielectric.

  The high-frequency line is formed on the second substrate 102 above the inner layer signal line 103 along the inner layer signal line 103 and on the upper surface of the second substrate 102 on which the groove 104 is formed. A signal line 103 and a ground conductive layer 205 constituting a microstrip line are provided.

  In the second embodiment, the groove 104 is formed immediately above the inner layer signal line 103. A ground conductive layer 205 is formed on the upper surface of the second substrate 102 including the inside of the groove 104. In the second embodiment, the ground conductive layer 205 is formed in a region other than the groove 104. Note that a dielectric substrate (not shown) may be formed below the first substrate 101. For example, four dielectric substrates are laminated below the first substrate 101, and six dielectric substrates in total are laminated. When a ground conductive layer is also provided below the inner layer signal line 103, the distance between the ground conductive layer and the inner layer signal line 103 is larger than the distance between the inner layer signal line 103 and the ground conductive layer 205.

  In the configuration described above, the width and depth of the groove 104 are characterized in that the desired characteristic impedance of the inner layer signal line 103 is obtained. Since the groove 104 is provided on the upper surface of the second substrate 102 on which the ground conductive layer 205 is formed, the groove 104 having a predetermined depth and width is formed after the second substrate 102 is formed on the inner signal line 103. By forming the electric field coupling strength between the inner signal line 103 and the ground conductive layer 205 can be adjusted later. As described above, also in the second embodiment, the characteristic impedance of the inner signal line 103 can be controlled after the second substrate 102 is formed.

  Next, the manufacturing method of the high frequency line in Embodiment 2 of this invention is demonstrated using FIG. 2A and FIG. 5A-FIG. 5C. 5A to 5C are cross-sectional views showing the state of an intermediate process for explaining the method of manufacturing the high-frequency line in Embodiment 2 of the present invention.

  First, as shown in FIG. 2A, the inner layer signal line 103 is formed on the first substrate 101 (first step). For example, a groove is formed in the line formation region of the first substrate 101 made of alumina ceramic. Next, copper (Cu) is deposited by a well-known plating method to form a Cu film. Thereafter, the Cu film is etched back by a chemical mechanical polishing method or the like, and the formed groove is filled with Cu, thereby forming the inner layer signal line 103 made of Cu.

  Next, as shown in FIG. 5A, the second substrate 102 is laminated on the surface of the first substrate 101 on which the inner signal line 103 is formed (second step). For example, the bonding surface (back surface) of the second substrate 102 is bonded to the bonding surface (upper surface) of the first substrate 101 on which the inner layer signal line 103 is formed by a known bonding technique. The steps described above are the same as those in the first embodiment.

  Next, as illustrated in FIG. 5B, a ground conductive layer 205 is formed on the upper surface of the second substrate 102. For example, the ground conductive layer 205 made of Cu can be formed by depositing Cu by a plating method or the like. The ground conductive layer 205 constitutes the inner layer signal line 103 and the microstrip line.

  Thereafter, a groove 104 is formed along the inner signal line 103 on the upper surface of the second substrate 102 above the inner signal line 103 (third step). In the second embodiment, the groove 104 is formed from above the ground conductive layer 205. Also in the second embodiment, the groove 104 is formed immediately above the inner signal line 103. In the formation of the groove 104, the width and depth of the groove 104 are formed so as to obtain a desired characteristic impedance of the inner signal line 103. As described above, the high-frequency line shown in FIG. 4A is obtained.

  Next, a simulation result of the characteristics of the high-frequency line in the second embodiment will be described. The first substrate 101 and the second substrate 102 were made of alumina ceramic, and the plate thickness H was 0.254 mm. Further, the thickness H ′ of the second substrate 102 in the groove portion 104 was set to 0.03 mm. In this case, the depth of the groove 104 is 0.251 mm. Further, a four-layer dielectric substrate of the same material and the same thickness is provided below the first substrate 101, and a ground conductive layer is provided between the layers. Assume that there is no layer.

  For example, although the design value of the width of the inner layer signal line 103 is 0.16 mm, the case where the width becomes 0.175 mm as a result of manufacture will be considered. In this case, as shown in FIG. 6B, a desired reflection characteristic of 30 dB or less cannot be obtained. On the other hand, by forming a groove portion 104 having a depth of 0.251 mm and a width G of 0.05 mm on the second substrate 102 on the inner layer signal line 103 formed with a width of 0.175 mm, FIG. As shown, a desired reflection characteristic of 30 dB or less can be obtained.

[Embodiment 3]
Next, a third embodiment of the present invention will be described. FIG. 7A is a block diagram showing the configuration of the high-frequency line in the first embodiment of the present invention. FIG. 7B is a plan view showing the configuration of the high-frequency line in the first embodiment of the present invention.

  The high-frequency line includes a first substrate 101, a second substrate 102 stacked on the first substrate 101, and an inner layer signal line 103 disposed between the first substrate 101 and the second substrate 102. Prepare. The first substrate 101 and the second substrate 102 are made of a dielectric.

  In addition, the high-frequency line includes two grooves 304 a and 304 b formed along the inner signal line 103 on the second substrate 102 above the inner signal line 103 and the second substrate 102 in which the grooves 304 a and 304 b are formed. An inner layer signal line 103 formed on the upper surface and a ground conductive layer 305 constituting a microstrip line are provided. The groove 304a and the groove 304b are arranged in parallel to each other.

  In the third embodiment, the grooves 304a and 304b are arranged with the inner layer signal line 103 sandwiched in plan view. In addition, a ground conductive layer 305 is formed on the upper surface of the second substrate 102 including the inside of the groove portions 304a and 304b. Note that a dielectric substrate (not shown) may be formed below the first substrate 101. For example, four dielectric substrates are laminated below the first substrate 101, and six dielectric substrates in total are laminated.

  In the configuration described above, the width and depth of each of the grooves 304a and 304b and the distance between the grooves 304a and 304b are characterized in that the desired characteristic impedance of the inner layer signal line 103 is obtained. . The high-frequency line in the third embodiment is different from the first embodiment in that the two high-frequency lines 304a and 304b are provided, and can be manufactured in the same manner as the high-frequency line in the first embodiment. In Embodiment 3, after the second substrate 102 is bonded to the first substrate 101, two grooves 304a and 304b may be formed on the upper surface of the second substrate 102 (third step).

  Also in the third embodiment, since the grooves 304a and 304b are provided on the upper surface of the second substrate 102 on which the ground conductive layer 305 is formed, after the second substrate 102 is formed on the inner signal line 103, By forming the grooves 304a and 304b having a predetermined depth and width at predetermined intervals, the electric field coupling strength between the inner signal line 103 and the ground conductive layer 305 can be adjusted later. Thus, according to the third embodiment, the characteristic impedance of the inner layer signal line 103 can be controlled after the second substrate 102 is formed.

  As described above, according to the present invention, since the groove portion is formed along the inner layer signal line on the second substrate above the inner layer signal line, the substrate thickness and the signal line width vary due to manufacturing tolerances and the like. Even so, a high-frequency line having a desired high-frequency characteristic can be formed.

  The present invention is not limited to the embodiment described above, and many modifications and combinations can be implemented by those having ordinary knowledge in the art within the technical idea of the present invention. It is obvious. For example, in the above description, the dielectric substrate made of alumina ceramic is used. However, the present invention is not limited to this, and the substrate may be made of another dielectric. In addition, the inner layer signal line is made of Cu, but is not limited to this, and may be made of a conductive material such as another metal.

  DESCRIPTION OF SYMBOLS 101 ... 1st board | substrate, 102 ... 2nd board | substrate, 103 ... Inner-layer signal track | line, 104 ... Groove part, 105 ... Ground conductive layer.

Claims (8)

A first step of forming an inner signal line on the first substrate;
A second step of laminating a second substrate on the surface of the first substrate on which the inner layer signal line is formed;
A third step of forming a groove along the inner layer signal line in the second substrate above the inner layer signal line;
A fourth step of forming a ground conductive layer constituting the inner signal line and the microstrip line on the upper surface of the second substrate in which the groove is formed, and
The width and depth of the groove are formed so that desired characteristic impedance of the inner layer signal line can be obtained. In the manufacturing method of the high frequency line according to claim 1,
The method for manufacturing a high-frequency line, wherein the groove is formed immediately above the inner-layer signal line. In the manufacturing method of the high frequency track according to claim 2,
The method of manufacturing a high-frequency line, wherein the ground conductive layer is formed in a region other than the groove. In the manufacturing method of the high frequency line according to claim 1,
A method for producing a high-frequency line, comprising forming the two grooves arranged with the inner layer signal line in plan view. A first substrate and a second substrate stacked on the first substrate;
An inner layer signal line disposed between the first substrate and the second substrate;
A groove formed along the inner layer signal line on the second substrate above the inner layer signal line;
A ground conductive layer formed on an upper surface of the second substrate in which the groove is formed and constituting the inner layer signal line and a microstrip line;
The width and depth of the groove are in a state where desired characteristic impedance of the inner layer signal line can be obtained. The high-frequency line according to claim 5,
The high-frequency line, wherein the groove is formed immediately above the inner-layer signal line. In the high frequency line according to claim 6,
The high-frequency line, wherein the ground conductive layer is formed in a region other than the groove. The high-frequency line according to claim 5,
A high-frequency line comprising the two groove portions arranged with the inner layer signal line in plan view.