Termination resistors and circuit boards

Abstract

A termination resistor that combines high-frequency characteristics with a low profile and can be mounted on a circuit board as a chip is provided. [Solution] The termination resistor 11 is a resistor set to a specific resistance value of 10 to 200 Ω. The termination resistor 11 includes a resistive layer 12 having a first surface 12a and a second surface 12b opposite the first surface 12a, a first electrode layer 13 laminated on the first surface 12a of the resistive layer 12, and a second electrode layer 14 laminated on the second surface 12b of the resistive layer 12. The resistive layer 12 is made of a resistive material having a resistivity ρ of 0.5 to 4.0 Ωcm.

Description

[Technical Field]

[0001] The present invention relates to a termination resistor and a circuit board. [Background technology]

[0002] In recent years, the rapid spread of high-speed communication technology has led to an expanding demand for high-frequency electronic circuits. Various resistors are used in high-frequency electronic circuits. For example, in high-frequency communications using frequencies above gigahertz, signals passing through transmission lines or bonding wires can be reflected at the termination of the transmission line or at the connection point with the bonding wire. This reflection can degrade signal quality and potentially cause communication errors. Transmission lines, in particular, have a specific characteristic impedance (e.g., 50 Ω), and reflections occur due to impedance mismatches at the termination of the transmission line. Termination resistors are designed to match this characteristic impedance and are connected to the termination of the transmission line to prevent signal reflections by matching the impedance. In other words, the use of termination resistors ensures that signals are properly processed at the termination of the transmission line, reducing high-frequency loss. This suppresses signal attenuation and loss and maintains communication quality. For example, Patent Document 1 discloses the use of chip resistors as 50 Ω termination resistors to achieve impedance matching. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6438569 Summary of the Invention [Problem to be solved by the invention]

[0004] As shown in Patent Document 1 (FIG. 2), a typical wire-bonded resistor is illustrated in FIG. 6, and a circuit board on which the resistor is mounted is illustrated in FIG. 7. As shown in FIG. 6, the resistor 1 includes a sheet-like resistive element 2 having a predetermined thickness and a predetermined cross-sectional area, two electrodes 3 and 4 formed on both sides of the resistive element 2, and an insulating plate 5 supporting the resistive element 2 and the electrodes 3 and 4. The resistor 1 has an element thickness L from the bottom surface of the insulating plate 5 to the top surface of the resistive element 2, and a mounting area A which is the sum of the surfaces of the electrodes 3 and 4 and the surface of the resistive element 2. As shown in FIG. 7, the resistor 1 is mounted on an AlN substrate 6 constituting a circuit board. The electrodes 3 and 4 are connected to other elements E1 and E2 by wires 7. However, in high-frequency electronic circuits, a problem arises in that parallel stray capacitance Cf occurs between the two electrodes 3 and 4 and the AlN substrate 6, adversely affecting the frequency characteristics of the circuit, such as band limiting.

[0005] Furthermore, with the recent trend toward miniaturization and integration of high-frequency electronic circuits, the size of termination resistors mounted on the circuits is also restricted. In particular, a low profile termination resistor is required to reduce the physical height of electronic components and integrated circuit packages. Furthermore, termination resistors are also required to have a predetermined mounting area for mounting on a circuit board using surface-mounted device (SMD) technology, chip-on-chip (CoC) technology, flip-chip technology, etc. For example, a mounting area of ​​approximately 0.001 mm 2 If it is smaller than this, wire bonding connection becomes difficult, so it is necessary to keep it within a certain size (for example, about 0.01 mm 2 A mounting area of ​​100Ω or more must be secured. On the other hand, the termination resistor must be set to a specific resistance value in the range of 10 to 200Ω (e.g., 50Ω, 75Ω, 110Ω, 120Ω, 150Ω, 200Ω) so that its resistance matches the characteristic impedance of the transmission line, etc. Until now, no termination resistor has existed that meets all of these requirements.

[0006] An object of the present invention is to provide a termination resistor that has both high frequency characteristics and a low profile and can be mounted on a circuit board as a chip, and a circuit board on which the termination resistor is mounted.

[0007] [Patent Document 1] Patent No. 6438569 [Means for solving the problem]

[0008] (Configuration 1) A termination resistor according to one embodiment of the present invention is a termination resistor set to a specific resistance value R of 10 to 200 Ω, a resistive layer having a first surface and a second surface opposite the first surface; a first electrode layer laminated on a first surface of the resistive layer; a second electrode layer laminated on a second surface of the resistance layer, The resistive layer is characterized by being made of a resistive material having a resistivity ρ of 0.5 to 4.0 Ωcm.

[0009] (Configuration 2) A termination resistor according to a further aspect of the present invention is the termination resistor of configuration 1, more preferably characterized in that the resistive material is made of SiC.

[0010] (Configuration 3) A further aspect of the present invention is a termination resistor of the configuration 1 or 2, more preferably, the element thickness L of the termination resistor is 0.2 mm or less and the mounting area A is 0.01 mm 2 The present invention is characterized in that:

[0011] (Configuration 4) A further aspect of the present invention is a termination resistor according to any one of the first to third configurations, wherein the mounting area A is preferably 0.01 to 0.18 mm 2 It is characterized in that:

[0012] (Configuration 5) A termination resistor according to a further aspect of the present invention is the termination resistor of any one of Configurations 1 to 4, more preferably characterized in that the resistance value R of the termination resistor is 50Ω.

[0013] (Configuration 6) A termination resistor according to a further aspect of the present invention is the termination resistor according to any one of the first to fifth aspects, characterized in that the thickness of the first electrode layer and the second electrode layer is 10 μm or less.

[0014] (Configuration 7) A circuit board according to one aspect of the present invention includes an AlN substrate and a termination resistor according to any one of configurations 1 to 6 mounted on the AlN substrate.

[0015] (Configuration 8) A circuit board according to a further aspect of the present invention is the circuit board of configuration 7, more preferably further comprising a first element and a second element; The first electrode layer of the termination resistor is wire-bonded to the first element, and the second electrode layer is electrically connected to a second element placed on a through-hole or conductor in the AlN substrate.

[0016] (Configuration 9) A circuit board according to a further aspect of the present invention is the circuit board of configuration 7, more preferably further comprising a first element and a second element; The first electrode layer of the termination resistor is connected to the first element by wire bonding, and the second electrode layer is electrically connected to the second element via a through-hole or conductor formed in the AlN substrate. [Effects of the Invention]

[0017] The termination resistor of the present invention has a first electrode layer and a second electrode layer laminated on the first and second surfaces of the resistive layer, respectively, which prevents the generation of "parallel stray capacitance" caused by the termination resistor and improves high-frequency characteristics when mounted on a circuit board. Furthermore, because the termination resistor has a low profile while still ensuring a practical mounting area, its size does not become a hindrance when mounting or packaging on a circuit board. Therefore, the termination resistor of the present invention achieves both high-frequency characteristics and a low profile, and can be mounted on a circuit board as a chip. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a schematic perspective view of a termination resistor according to an embodiment of the present invention; [Figure 2] FIG. 2 is a cross-sectional view of the termination resistor of FIG. 1. [Figure 3] 1 is a schematic diagram showing a first example of a circuit board in which a termination resistor according to an embodiment of the present invention is mounted on an AlN substrate. [Figure 4] FIG. 4 is a schematic diagram showing a second example of a circuit board in which a termination resistor according to an embodiment of the present invention is mounted on an AlN substrate. [Figure 5] 1 is a graph showing high-frequency characteristics (reflection) of Examples 2 and 3 of the present invention and Comparative Example 6. [Figure 6] FIG. 1 is a schematic perspective view showing a resistor having a conventional configuration; [Figure 7] FIG. 1 is a schematic diagram showing a first example of a circuit board in which a resistor having a conventional configuration is mounted on an AlN substrate. [Figure 8] FIG. 10 is a schematic diagram showing a second example (configuration of Comparative Example 6) of a circuit board in which a resistor with a conventional configuration is mounted on an AlN substrate. DETAILED DESCRIPTION OF THE INVENTION

[0019] The termination resistor 11 according to one embodiment of the present invention is a chip mounted on a circuit board for high-frequency electronic circuits using SMD, CoC, or flip-chip technology. The termination resistor 11 is connected to a transmission line or wire on the circuit board and has a resistance value R set to match the characteristic impedance of the transmission line or wire. Matching the resistance value R of the termination resistor 11 to the characteristic impedance of the transmission line or wire minimizes signal reflection and loss at the termination or connection. This resistance value R is typically 10 to 200 Ω. In this embodiment, the resistance value R is set to 50 Ω for use in the termination or connection of a high-frequency circuit. However, the resistance value R may also be other specific values, such as 75 Ω (television transmission, satellite communication, etc.), 110 Ω (differential signal communication, high-speed digital communication, etc.), 120 Ω (specific digital signal standards, etc.), 150 Ω (specific digital signal standards, etc.), or 200 Ω (specific digital signal standards, etc.).

[0020] FIG. 1 is a schematic perspective view of a termination resistor 11 according to this embodiment. FIG. 2 is a cross-sectional view of the termination resistor 11. As shown in FIG. 1, the termination resistor 11 has a three-dimensional shape with rectangular surfaces. The termination resistor 11 has a length, a width, and an element thickness L. The product of the length and the width (cross-sectional area) represents its mounting area A. The element thickness L coincides with the direction of current flow through the element. The element thickness L is the distance between the outer surface of the first electrode layer 13 and the outer surface of the second electrode layer 14. However, as will be described later, the thicknesses of the electrode layers 13 and 14 are sufficiently thin compared to the thickness of the resistive layer 12 and are therefore negligible. In other words, the element thickness L essentially represents the thickness of the resistive layer 12, regardless of the thicknesses of the electrode layers 13 and 14. It goes without saying that the termination resistor of the present invention may have other three-dimensional shapes as long as it can perform its function.

[0021] As shown in FIG. 2, the termination resistor 11 includes a resistive layer 12 having a first surface 12a and a second surface 12b opposite the first surface 12a, a first electrode layer 13 stacked on the first surface 12a of the resistive layer 12, and a second electrode layer 14 stacked on the second surface 12b of the resistive layer 12.

[0022] The resistive layer 12 is made of a resistive material having a resistivity of 0.5 to 4.0 Ω·cm. This resistive material is preferably selected from silicon carbide (SiC). The resistive layer 12 is formed to a predetermined thickness and cross-sectional area. In this embodiment, tetraethoxysilane as a silicon source, novolac phenolic resin as a carbon source, maleic acid as a catalyst, and ethanol as a solvent are mixed to form a syrup-like mixture. The syrup-like mixture is gradually heated from room temperature to 200°C and thermally cured to form a resinous solid. This resinous solid is then carbonized at 900°C in an argon atmosphere to form a carbide. This carbide is then heated to 1900°C in an argon atmosphere and maintained therein to form silicon carbide powder. The silicon carbide powder is then placed in a hot press, gradually heated from room temperature to 1500°C under vacuum conditions, maintained therein, and then cooled to produce a silicon carbide (SiC) sintered body. The specified resistivity can be achieved by adjusting the amount of impurities (nitrogen, carbon, metals, etc.) contained in the silicon carbide (SiC) sintered body (here, the amount of nitrogen contained in the silicon carbide (SiC) sintered body was adjusted to 40 ppm or less).

[0023] The first electrode layer 13 and the second electrode layer 14 are made of a highly conductive metal material such as copper (Cu) or gold (Au). The thickness of the first electrode layer 13 and the second electrode layer 14 is preferably 10 μm or less. Specifically, the thickness of the first electrode layer 13 and the second electrode layer 14 is 3 μm. The thin plate-like first electrode layer 13 and the second electrode layer 14 may be joined to the first surface 12a and the second surface 12b of the resistance layer 12, respectively, by pressure welding or sintering. Alternatively, the first electrode layer 13 and the second electrode layer 14 may be formed by sputtering or plating a metal material onto the first surface 12a and the second surface 12b of the resistance layer 12, respectively.

[0024] The termination resistor 11 preferably has the following chip size. In order to reduce the height of the chip, it is preferable that the element thickness L of the termination resistor 11 is 0.2 mm or less. In this embodiment, the element thickness L is set to 0.09 to 0.2 mm. Furthermore, in order to enable the termination resistor 11 to be mounted on a circuit board and / or to enable wire bonding connection with the termination resistor 11, the mounting area A is set to 0.01 mm. 2 On the other hand, in order to avoid an increase in the size of the chip in the planar direction, the mounting area A is set to 0.18 mm 2 It is preferable that:

[0025] FIG. 3 is a schematic diagram showing an example (first embodiment) of a circuit board 10 in which a termination resistor 11 according to this embodiment is mounted on an AlN substrate 16. As shown in FIG. 3, the circuit board 10 includes an AlN substrate 16 and a termination resistor 11 mounted on the AlN substrate 16. The circuit board 10 also includes a first element E1 (not shown) and a second element E2 (capacitor). The second element E2 is installed on a through-hole 18 formed in the AlN substrate 16. Note that a conductor such as gold plating or copper foil may be formed instead of the through-hole 18. The first electrode layer 13 of the termination resistor 11 is wire-bonded to the first element E1, and the second electrode layer 14 is electrically connected to the second element E2. In contrast, the conventional circuit configuration of FIG. 6 has the same circuit configuration as that of FIG. 3. However, a parallel stray capacitance Cf occurs between the two electrodes 3 and 4 and the AlN substrate 6, adversely affecting the frequency characteristics of the circuit, such as band limiting. That is, in the circuit board 10, the first electrode layer 13 and the second electrode layer 14 are provided on the first surface 12a and the second surface 12b of the resistive layer 12, respectively, thereby preventing the parallel stray capacitance Cf caused by the termination resistor 11, which is a problem in conventional circuit configurations. Therefore, the termination resistor 11 of this embodiment improves high-frequency characteristics compared to conventional ones. Furthermore, in the circuit board 10 of FIG. 3, the termination resistor 11 is mounted on the second element E2, and because the termination resistor 11 has a low profile (element thickness L≦0.2 mm) while ensuring a practical mounting area A, the risk of it causing problems in mounting and packaging is reduced.

[0026] FIG. 4 is a schematic diagram showing another example (second embodiment) of a circuit board 10 in which a termination resistor 11 according to this embodiment is mounted on an AlN substrate 16. As shown in FIG. 4, the circuit board 10′ includes an AlN substrate 16 and a termination resistor 11 mounted on the AlN substrate 16. The circuit board 10′ also includes a first element E1 and a second element E2. For example, the first element E1 is an electroabsorption modulated laser (EML), and the second element E2 is a multilayer ceramic capacitor (MLCC). The termination resistor 11 is mounted on a conductor 19 formed on the AlN substrate 16. Note that a through-hole may be formed instead of the conductor 19. The first electrode layer 13 of the termination resistor 11 is wire-bonded to the first element E1, and the second electrode layer 14 is electrically connected to the second element E2 via the conductor 19 (or through-hole) formed on the AlN substrate 16. Similarly, in the circuit board 10', the first electrode layer 13 and the second electrode layer 14 are provided on the first surface 12a and the second surface 12b of the resistive layer 12, respectively, thereby preventing the parallel stray capacitance Cf caused by the termination resistor 11, which was a problem in conventional circuit configurations. Therefore, the termination resistor 11 of this embodiment has improved high-frequency characteristics compared to conventional ones. Furthermore, in the circuit board 10' of FIG. 4, the termination resistor 11 has a low profile (element thickness L≦0.2 mm) while ensuring a practical mounting area A, thereby reducing the risk of problems during mounting and packaging. [Example]

[0027] - Low profile and mountability The termination resistor 11 of this embodiment has a resistive layer 12 formed of SiC having a specific resistance of 0.5 to 4.0 Ω·cm. This allows for a desired resistance value (50 Ω), a low profile (T≦0.2 mm), and a mounting area (S≧0.01 mm) that allows it to be mounted as a chip on an electronic circuit. 2) can be satisfied. Table 1 below shows the relationship between element thickness L and mounting area A when the resistance value is set to 50 Ω and SiC (specific resistance 0.5 to 4.0 Ω·cm) is selected for the resistive layer 12, and when other materials (specific resistance 0.0002, 0.03) are selected. Here, the formula: resistance value R = specific resistance ρ × [element thickness L / mounting area A] holds.

[0028] [Table 1]

[0029] According to Table 1, in Examples 1 to 7, in the termination resistors with a resistance value R of 50 Ω, the resistive layer is made of SiC with a specific resistance ρ of 0.5 to 4.0 Ω·cm, and the element thickness L is set to 0.09 to 0.20 mm. In Examples 1 to 7, the mounting area A is set to 0.01 to 0.16 mm. 2 Therefore, it was found that an area was secured that could be mounted on a circuit board and could be connected by wire bonding.

[0030] On the other hand, Comparative Example 1 used a resistive material with a resistivity ρ of 0.0002 Ω·cm for the resistive layer. For example, the resistive material was a sintered body made by mixing alumina powder and nichrome powder in a volume ratio of 20:80 and sintering the mixture. Comparative Examples 2 to 5 used a resistive material with a resistivity ρ of 0.03 Ω·cm for the resistive layer. For example, the resistive material was a sintered body made by mixing alumina powder and nichrome powder in a volume ratio of 70-80:30-20 and sintering the mixture. For the resistive materials of these comparative examples, please refer to JP 2023-78340 A as prior art.

[0031] In Comparative Examples 1 to 3, when the element thickness L was set to 0.10 to 0.20 mm, the mounting area A was 0.0012 mm 2 On the other hand, in Comparative Example 4, in order to achieve mountability, the mounting area A was set to 0.0330 mm 2However, the element thickness L was 5.5 mm, which was out of the standard, and it was not possible to achieve a low profile. Furthermore, in Comparative Example 5, in order to achieve both a low profile and mountability, the element thickness L was set to 0.1 mm and the mounting area A was set to 0.0333 mm 2 However, the resistance value R condition could not be achieved.

[0032] Table 2 shows the relationship between element thickness L and mounting area A when the resistance is set to 100 Ω and SiC (specific resistance 0.5 to 4.0 Ω·cm) is selected for the resistive layer 12, and when other materials (specific resistance 0.0002, 0.03) are selected. Here too, the formula resistance R = specific resistance ρ × [element thickness L / mounting area A] holds true.

[0033] [Table 2]

[0034] According to Table 2, in Examples 8 to 14, in the termination resistors with a resistance value R of 100 Ω, the resistive layer is made of SiC with a specific resistance ρ of 0.5 to 4.0 Ω·cm, and the element thickness L is set to 0.09 to 0.20 mm. In Examples 8 to 14, the mounting area A is set to 0.01 to 0.08 mm. 2 Therefore, it was found that an area was secured that could be mounted on a circuit board and could be connected by wire bonding.

[0035] On the other hand, Comparative Example 7 used a resistive material with a resistivity ρ of 0.0002 Ω·cm for the resistive layer. For example, the resistive material was a sintered body made by mixing alumina powder and nichrome powder in a volume ratio of 20:80 and sintering the mixture. Comparative Examples 8 to 11 used a resistive material with a resistivity ρ of 0.03 Ω·cm for the resistive layer. For example, the resistive material was a sintered body made by mixing alumina powder and nichrome powder in a volume ratio of 70-80:30-20 and sintering the mixture. For the resistive materials of these comparative examples, please refer to JP 2023-78340 A as prior art.

[0036] In Comparative Examples 7 to 9, when the element thickness L was set to 0.10 to 0.20 mm, the mounting area A was 0.0006 mm 2 On the other hand, in Comparative Example 10, in order to achieve mountability, the mounting area A was set to 0.0170 mm 2 However, the element thickness L was 5.66 mm, which was out of the standard, and it was not possible to achieve a low profile. Furthermore, in Comparative Example 11, in order to achieve both a low profile and mountability, the element thickness L was set to 0.1 mm and the mounting area A was set to 0.0169 mm 2 However, the resistance value R condition could not be achieved.

[0037] Table 3 shows the relationship between element thickness L and mounting area A when the resistance is set to 25 Ω and SiC (specific resistance 0.5 to 4.0 Ω·cm) is selected for the resistive layer 12, and when other materials (specific resistance 0.0002, 0.03) are selected. Here too, the formula resistance R = specific resistance ρ × [element thickness L / mounting area A] holds true.

[0038] [Table 3]

[0039] According to Table 3, in Examples 15 to 21, in the termination resistors with a resistance value R of 25 Ω, the resistive layer is made of SiC with a specific resistance ρ of 0.5 to 4.0 Ω·cm, and the element thickness L is set to 0.09 to 0.20 mm. In Examples 15 to 21, the mounting area A is set to 0.04 to 0.18 mm. 2 Therefore, it was found that an area was secured that could be mounted on a circuit board and could be connected by wire bonding.

[0040] On the other hand, Comparative Example 12 used a resistive material with a resistivity ρ of 0.0002 Ω·cm for the resistive layer. For example, the resistive material was a sintered body made by mixing alumina powder and nichrome powder in a volume ratio of 20:80 and sintering the mixture. Comparative Examples 13 to 16 used a resistive material with a resistivity ρ of 0.03 Ω·cm for the resistive layer. For example, the resistive material was a sintered body made by mixing alumina powder and nichrome powder in a volume ratio of 70-80:30-20 and sintering the mixture. For the resistive materials of these comparative examples, please refer to JP 2023-78340 A as prior art.

[0041] In Comparative Examples 12 to 14, when the element thickness L was set to 0.10 to 0.20 mm, the mounting area A was 0.003 mm 2 On the other hand, in Comparative Example 10, in order to achieve mountability, the mounting area A was set to 0.0679 mm 2 However, the element thickness L was 5.66 mm, which was out of the standard, and it was not possible to achieve a low profile. Furthermore, in Comparative Example 16, in order to achieve both a low profile and mountability, the element thickness L was set to 0.1 mm and the mounting area A was set to 0.0682 mm 2 However, the resistance value R condition could not be achieved.

[0042] High frequency characteristics The high-frequency characteristics of a circuit board equipped with a termination resistor of the present invention were evaluated. First, a circuit board (configuration shown in FIG. 4) equipped with a termination resistor of the present invention (Examples 2 and 3) was fabricated. As Comparative Example 6, the circuit board shown in FIG. 7 was fabricated. The circuit board of the Example (FIG. 4) and the circuit board of Comparative Example 6 (FIG. 8) have the same basic configuration, but differ in that a conventional resistor is used in the structure shown in FIG. 8. That is, as shown in FIG. 8, two electrodes 3 and 4 provided on both sides of the resistive element 2 of the resistor 1 are connected to a first element E1 and a second element E2, respectively, via two wires 17. Here, the resistor used in Comparative Example 6 operates at 50 Ω, and its dimensions are an element thickness L of 0.42 mm and a mounting area A of 0.1872 mm. 2The reflection characteristics in the high frequency band (gigahertz band) of Examples 2 and 3 and Comparative Example 6 were evaluated and compared. The evaluation method was as follows.

[0043] <Evaluation method> The resistance of the termination resistor mounted on the circuit board with the GSG transmission line was evaluated by S11 via a GSG probe using a one-port network analyzer (Keysight, model number: PNA).

[0044] FIG. 5 is a graph showing frequency (GHz) versus reflection (dB) for Examples 2 and 3 and Comparative Example 6. Here, the smaller the reflection (dB) (i.e., the more negative the value), the better the high-frequency characteristics. FIG. 5 shows that the reflection of Comparative Example 6 is significantly greater than that of Examples 2 and 3. This demonstrates that mounting the termination resistor of the present invention on a circuit board without generating stray capacitance improves the high-frequency characteristics of the circuit board.

[0045] The present invention is not limited to the above-described embodiments, and can be implemented in various forms within the technical scope of the present invention. [Explanation of symbols]

[0046] 1 resistor 2 resistors 3, 4 electrodes 5. Insulating plate 6. AlN substrate 7 wire 10 Circuit Board 11 Termination resistor 12 resistance layer 12a 1st page 12b Side 2 13 First electrode layer 14 Second electrode layer 16 AlN substrate 17 wires 18 through holes 19 Conductor A Mounting area L element height E1 First element E2 Second element Cf stray capacitance

Claims

1. A termination resistor set to a specific resistance value R between 10 and 200 Ω, a resistive layer having a first surface and a second surface opposite the first surface; a first electrode layer laminated on a first surface of the resistive layer; a second electrode layer laminated on a second surface of the resistive layer, The resistor layer is made of a resistive material having a resistivity ρ of 0.5 to 4.0 Ωcm.

2. 2. The termination resistor according to claim 1, wherein the resistive material is made of SiC.

3. The element thickness L of the termination resistor is 0.2 mm or less, and the mounting area A is 0.01 mm ２ 3. The termination resistor according to claim 2, wherein:

4. The mounting area A is 0.01 to 0.18 mm ２ 4. The termination resistor according to claim 3, wherein:

5. 5. The termination resistor according to claim 4, wherein the resistance value R of the termination resistor is 50 Ω.

6. 6. The termination resistor according to claim 5, wherein the thickness of the first electrode layer and the second electrode layer is 10 [mu]m or less.

7. A circuit board comprising: an AlN substrate; and the termination resistor according to claim 1 mounted on the AlN substrate.

8. the circuit board further comprises a first element and a second element; 8. The circuit board according to claim 7, wherein the first electrode layer of the termination resistor is wire-bonded to the first element, and the second electrode layer is electrically connected to a second element installed on a through-hole or conductor of the AlN substrate.

9. the circuit board further comprises a first element and a second element; 8. The circuit board according to claim 7, wherein the first electrode layer of the termination resistor is connected to the first element by wire bonding, and the second electrode layer is electrically connected to the second element via a through hole or a conductor formed in the AlN substrate.

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