Electric circuit board

Abstract

This electric circuit board comprises: an insulating board (1); conductor patterns (2), (3), (5) which are formed on the surface of the insulating board (1) and on which a high-frequency signal is incident; and temperature measurement patterns (11)-(15), (21)-(24) which are formed on the surface of the insulating board (1) and have an infrared emissivity higher than the infrared emissivity of the conductor patterns (2), (3), (5).

Description

Electrical circuit board

[0001] The present disclosure relates to an electric circuit board having a conductor pattern formed on the surface of the board.

[0002] Patent Document 1 discloses an invention that focuses on the problem that electronic components such as semiconductors can become damaged or malfunction when they reach high temperatures in wiring boards on which electronic components are mounted. Patent Document 1 discloses a wiring board that has a heat radiation layer that covers part or all of the surface on which conductor patterns on which electronic components are mounted are formed, thereby improving the heat dissipation properties of the wiring board surface and suppressing the temperature rise of the electronic components.

[0003] Japanese Patent Application Laid-Open No. 2008-251950

[0004] On the other hand, electric circuit boards are becoming increasingly dense and powerful, and there is a demand to measure the surface temperature of insulating substrates or the temperature of conductor patterns formed on the surface of insulating substrates, particularly in electric circuit boards on which high-frequency circuits are mounted.

[0005] The present disclosure has been made in consideration of the above points, and aims to provide an electric circuit board that can measure the temperature of a conductor pattern formed on the surface of the board without contacting the conductor pattern.

[0006] The electric circuit board according to the present disclosure comprises an insulating substrate, a conductor pattern formed on the surface of the insulating substrate and onto which a high-frequency signal is incident, and a temperature measurement pattern formed on the surface of the insulating substrate and having an infrared emissivity higher than that of the conductor pattern.

[0007] According to the present disclosure, by using a temperature measurement pattern, the surface temperature of a conductor pattern located directly below the temperature measurement pattern or the surface temperature of an insulating substrate can be measured in a non-contact manner with high accuracy.

[0008] Fig. 1 is a plan view of a main part of an electric circuit board according to embodiment 1. Fig. 2 is a cross-sectional view taken along line AA in Fig. 1. Fig. 3 is a plan view of a main part of an electric circuit board according to embodiment 2.

[0009] Embodiment 1. An electric circuit board according to embodiment 1 will be described using Figures 1 and 2. The electric circuit board according to embodiment 1 is an electric circuit board on which a high-frequency circuit is mounted and in which conductor patterns 2 and 3 are formed on the surface of an insulating substrate 1. The electric circuit board according to embodiment 1 includes an insulating substrate 1, a first conductor pattern 2, a second conductor pattern 3, a ground conductor 4, and first to fifth temperature-measurement patterns 11 to 15.

[0010] A first conductor pattern 2 and a second conductor pattern 3 are formed on the front surface of an insulating substrate 1, and a ground conductor 4 is formed on the back surface of the insulating substrate 1. Each of the first conductor pattern 2 and the second conductor pattern 3 is a microstrip line formed between the ground conductor 4. Note that each of the first conductor pattern 2 and the second conductor pattern 3 may form a coplanar line or a differential line.

[0011] The first conductor pattern 2 and the second conductor pattern 3 are metal wiring layers formed by adhering or vapor-depositing copper or gold foil onto the surface of the insulating substrate 1 and forming fine circuit patterns by etching, etc. The first conductor pattern 2 and the second conductor pattern 3 are each formed on the surface of the insulating substrate 1 with their metal surfaces exposed.

[0012] As shown in Fig. 1, the first conductor pattern 2 has a line 2a with a characteristic impedance of 50 Ω and a thin line portion 2b with a narrower line width than the line 2a. As shown in Fig. 1, the second conductor pattern 3 has a line 3a with a characteristic impedance of 50 Ω and a bent portion 3b formed by bending the line 3a. The bent portion 3b shown in Fig. 1 is a 90-degree bend, but it may also be a bent portion curved in an arc.

[0013] A high-frequency signal is transmitted to each of the first conductor pattern 2 and the second conductor pattern 3. As high-frequency currents caused by the high-frequency signal flow through each of the first conductor pattern 2 and the second conductor pattern 3, the first conductor pattern 2 and the second conductor pattern 3 generate heat due to conductor loss and dielectric loss, resulting in a temperature rise. The conductor loss in each of the first conductor pattern 2 and the second conductor pattern 3 is due to the current amplitude of the high-frequency signal, and the dielectric loss in each of the first conductor pattern 2 and the second conductor pattern 3 is due to the voltage amplitude (electric field amplitude) of the high-frequency signal.

[0014] Therefore, in order to measure the surface temperatures of the first conductor pattern 2 and the second conductor pattern 3, it is conceivable to use an infrared thermograph (infrared thermography camera) or an infrared radiation thermometer, which can measure the temperature of the first conductor pattern 2 and the second conductor pattern 3 without contact. Measuring the surface temperature with an infrared thermograph or an infrared radiation thermometer has the advantage that it has almost no effect on the object and can measure the temperature in real time, because it detects the temperature using infrared rays emitted from the object.

[0015] Because the first conductor pattern 2 and the second conductor pattern 3 are each made of metal, such as copper or gold, the infrared emissivity of the metal is low, at 0.2 or less, making it impossible to accurately measure the surface temperatures of the first conductor pattern 2 and the second conductor pattern 3 using an infrared thermograph or an infrared radiation thermometer. In other words, the surface temperatures of the first conductor pattern 2 and the second conductor pattern 3 are not suitable for surface temperature measurement, which detects the temperatures using infrared rays radiated from the metal surfaces of the first conductor pattern 2 and the second conductor pattern 3.

[0016] Each of the first temperature measurement pattern 11 to the fifth temperature measurement pattern 15 is formed by a solder resist pattern made of an insulating material such as resin or ceramics. The first temperature measurement pattern 11 to the fifth temperature measurement pattern 15 can be formed by a general circuit formation process without using a special manufacturing process, and does not result in a significant increase in cost.

[0017] That is, each of the first temperature measurement pattern 11 to the fifth temperature measurement pattern 15 is a solder resist pattern formed by applying a solder resist made of an insulating material, either resin or ceramic, onto the surface of an insulating substrate 1 on which a first conductor pattern 2 and a second conductor pattern 3 are formed, and then finely forming the solder resist pattern by etching or the like.

[0018] Each of the first temperature measurement pattern 11 to the fifth temperature measurement pattern 15 may be formed as a solder resist pattern by a method such as screen printing. Resin or ceramics is generally known to have high infrared emissivity.

[0019] Each of the first temperature measurement pattern 11 to the fifth temperature measurement pattern 15 has the surface of a resin or ceramic solder resist exposed, and is formed on the surface of the first conductor pattern 2, the surface of the second conductor pattern 3, and the surface of the insulating substrate 1. The infrared emissivity of the resin or ceramic solder resist constituting each of the first temperature measurement pattern 11 to the fifth temperature measurement pattern 15 is sufficiently higher than the infrared emissivity of the metal constituting each of the first conductor pattern 2 and the second conductor pattern 3, and is 0.8 or higher.

[0020] Therefore, by detecting the infrared rays emitted from the surface of the solder resist of each of the first temperature measurement pattern 11 to the fifth temperature measurement pattern 15 using an infrared thermograph or an infrared radiation thermometer to detect the temperature, the surface temperatures of the first conductor pattern 2, the second conductor pattern 3 and the insulating substrate 1 can be measured with high accuracy.

[0021] The first temperature measurement pattern 11 is formed in a rectangular shape on the surface of the line 2a of the first conductor pattern 2, spaced apart from both sides of the line 2a. That is, the first temperature measurement pattern 11 is locally arranged inside the surface of the line 2a so as to avoid the edges of the line 2a.

[0022] The length of the long side of the first temperature measurement pattern 11 is equal to or longer than the wavelength of the infrared radiation. When infrared thermography is used to detect the infrared radiation emitted from the surface of the first temperature measurement pattern 11 to detect the temperature, i.e., to measure the temperature, the length of the long side of the first temperature measurement pattern 11 is equal to or longer than the minimum spatial resolution of the infrared thermography. In the first embodiment, the length of the long side of the first temperature measurement pattern 11 is equal to or longer than several tens of micrometers, preferably several micrometers, and is optimally the same as the size of the minimum spatial resolution, i.e., the length of the minimum spatial resolution. The thickness of the first temperature measurement pattern 11 is equal to or shorter than several tens of micrometers, preferably several micrometers.

[0023] Furthermore, when an infrared radiation thermometer is used to detect infrared rays emitted from the surface of the first temperature-measurement pattern 11 to detect temperature, i.e., measure temperature, the length of the long side of the first temperature-measurement pattern 11 is optimally equal to or longer than the minimum spot diameter of the infrared radiation thermometer, i.e., the same length as the minimum spot diameter.

[0024] 1 shows one first temperature measurement pattern 11, but if there are multiple locations on the line 2a where the temperature needs to be measured, multiple first temperature measurement patterns 11 are arranged locally on the inside surface of the line 2a corresponding to each of the multiple locations. It is desirable that the first temperature measurement patterns 11 be formed locally in areas of the line 2a that are the heat dissipation source and have high thermal resistance or high loss density.

[0025] As described above, because the first temperature-measurement pattern 11 is formed locally on the surface of the line 2a, it does not increase electrical loss and therefore its effect on high-frequency loss can be suppressed, and the surface temperature of the line 2a in the first conductor pattern 2 can be measured with high accuracy using an infrared thermograph or an infrared radiation thermometer while maintaining the high-frequency characteristics of the high-frequency circuit. Moreover, when a high-frequency current flows through the first conductor pattern 2, the electric field strength increases along the sides of the line 2a, i.e., at the edges, so because the first temperature-measurement pattern 11 is formed to avoid the edges of the line 2a, it does not increase electrical loss in the high-frequency circuit.

[0026] The second temperature-measurement pattern 12 is formed in a rectangular shape on the surface of the thin line portion 2 b of the first conductor pattern 2, spaced apart from both sides of the thin line portion 2 b. That is, the second temperature-measurement pattern 12 is locally disposed inside the surface of the thin line portion 2 b so as to avoid the edges of the thin line portion 2 b.

[0027] The length of the long side of the second temperature-measurement pattern 12 is equal to or longer than the wavelength of infrared light, the minimum spatial resolution of infrared thermography, or the minimum spot diameter of an infrared radiation thermometer, similar to the length of the long side of the first temperature-measurement pattern 11, and is optimally equal to the size of the minimum spatial resolution or the size of the minimum spot diameter. The thickness of the second temperature-measurement pattern 12 is equal to or shorter than several tens of μm, preferably equal to or shorter than several μm, similar to the thickness of the first temperature-measurement pattern 11.

[0028] In the first conductor pattern 2, temperature measurement in the thin line portion 2b, where the current density is high and the temperature rise is higher than in the line 2a, can be performed with high precision by detecting infrared rays emitted from the surface of the second temperature measurement pattern 12 using an infrared thermography or an infrared radiation thermometer.

[0029] In this case, since the second temperature-measuring pattern 12 is formed locally on the surface of the thin line portion 2b, it does not increase electrical loss, so it is possible to suppress the effect on high-frequency loss and maintain the high-frequency characteristics of the high-frequency circuit. Moreover, when a high-frequency current flows through the first conductor pattern 2, the electric field strength increases along the sides of the thin line portion 2b, i.e., at the edges. However, since the second temperature-measuring pattern 12 is formed so as to avoid the edges of the thin line portion 2b, it does not increase electrical loss in the high-frequency circuit.

[0030] The third temperature-measurement patterns 13 are formed on the surface of the bent portion 3b formed by bending the line 3a of the second conductor pattern 3, and are spaced apart along both sides of the bent portion 3b. In the first embodiment, the planar shape of the third temperature-measurement patterns 13 is L-shaped. The third temperature-measurement patterns 13 are locally arranged on the inside, on the inner corner side of the surface of the bent portion 3b, so as to avoid the edge of the bent portion 3b.

[0031] The length of the long side of the third temperature measurement pattern 13, like the length of the long side of the first temperature measurement pattern 11, is equal to or longer than the wavelength of infrared light, the minimum spatial resolution of infrared thermography, or the minimum spot diameter of an infrared radiation thermometer, and is optimally equal to the size of the minimum spatial resolution or the size of the minimum spot diameter. In the first embodiment, the long side of the third temperature measurement pattern 13 is an L-shaped portion. Similarly to the thickness of the first temperature measurement pattern 11, the thickness of the third temperature measurement pattern 13 is equal to or shorter than several tens of μm, preferably equal to or shorter than several μm.

[0032] In the second conductor pattern 3, temperature measurement at the bend 3b, where the current density is high and the temperature rise is higher than in the straight portion of the line 3a, can be performed with high accuracy by detecting infrared rays emitted from the surface of the third temperature measurement pattern 13 using an infrared thermography or an infrared radiation thermometer.

[0033] In this case, since the third temperature-measuring pattern 13 is formed locally on the surface of the bent portion 3b, it does not increase electrical loss, so it is possible to suppress the effect on high-frequency loss and maintain the high-frequency characteristics of the high-frequency circuit. Moreover, when a high-frequency current flows through the second conductor pattern 3, the electric field strength increases along the side of the bent portion 3b, i.e., at the edge. However, since the third temperature-measuring pattern 13 is formed so as to avoid the edge of the bent portion 3b, it does not increase electrical loss in the high-frequency circuit.

[0034] In Figure 1, no temperature measurement pattern is shown on the straight portion of the line 3a in the second conductor pattern 3, but just as the first temperature measurement pattern 11 is formed on the surface of the line 2a in the first conductor pattern 2, one or more first temperature measurement patterns 11 are locally arranged inside the surface of the straight portion of the line 3a at the location where it is desired to measure the temperature of the line 3a.

[0035] The fourth temperature-measuring pattern 14 is formed in a rectangular shape on the surface of the insulating substrate 1, spaced apart from one side of the line 2a in the first conductor pattern 2. That is, the fourth temperature-measuring pattern 14 is locally arranged on the surface of the insulating substrate 1, facing and spaced apart from one side of the line 2a so as to avoid the edge of the line 2a.

[0036] The fifth temperature-measuring pattern 15 is formed in a rectangular shape on the surface of the insulating substrate 1 at a distance along the other side of the line 2a of the first conductor pattern 2. That is, the fifth temperature-measuring pattern 15 is locally arranged on the surface of the insulating substrate 1 facing the other side of the line 2a at a distance so as to avoid the edge of the line 2a.

[0037] The length of each of the long sides of the fourth temperature-measurement pattern 14 and the fifth temperature-measurement pattern 15 is equal to or longer than the wavelength of infrared light, the minimum spatial resolution of infrared thermography, or the minimum spot diameter of an infrared radiation thermometer, similar to the length of the long side of the first temperature-measurement pattern 11, and is optimally equal to the size of the minimum spatial resolution or the size of the minimum spot diameter. Furthermore, the thickness of each of the fourth temperature-measurement pattern 14 and the fifth temperature-measurement pattern 15 is equal to or shorter than several tens of μm, preferably equal to or shorter than several μm, similar to the thickness of the first temperature-measurement pattern 11.

[0038] Heat is conducted from the high temperature portion of the line 2a of the first conductor pattern 2 to the surface of the insulating substrate 1, and the temperature of the surface of the insulating substrate 1, which has risen in temperature, can be measured with high precision by detecting the infrared rays emitted from the surfaces of the fourth temperature measurement pattern 14 and the fifth temperature measurement pattern 15 using an infrared thermography or an infrared radiation thermometer.

[0039] In this case, since the fourth temperature measurement pattern 14 and the fifth temperature measurement pattern 15 are each formed locally on the surface of the insulating substrate 1, they do not increase electrical loss, so the effect on high-frequency loss can be suppressed and the high-frequency characteristics of the high-frequency circuit can be maintained. Moreover, when a high-frequency current flows through the first conductor pattern 2, the electric field strength increases along the sides of the line 2a, i.e., at the edges. However, since the fourth temperature measurement pattern 14 and the fifth temperature measurement pattern 15 are formed on the surface of the insulating substrate 1, avoiding the edges of the line 2a, they do not increase electrical loss to the high-frequency circuit.

[0040] 1 shows one each of the fourth temperature measurement pattern 14 and the fifth temperature measurement pattern 15, but if there are multiple locations where it is desired to measure the temperature on the surface of the insulating substrate 1 near the line 2a, multiple fourth temperature measurement patterns 14 and multiple fifth temperature measurement patterns 15 corresponding to each of the multiple locations are locally arranged on the surface of the insulating substrate 1 near the line 2a. It is desirable that the fourth temperature measurement pattern 14 and the fifth temperature measurement pattern 15 be locally formed at positions spaced apart along the sides of a portion of the line 2a, which is the heat dissipation source, where the thermal resistance or loss density is high.

[0041] In addition, although FIG. 1 does not show any temperature measurement patterns in the straight portion of the line 3 a in the second conductor pattern 3, just as the fourth temperature measurement pattern 14 and the fifth temperature measurement pattern 15 are formed on the surface of the insulating substrate 1 at a distance from each other on both sides of the line 2 a of the first conductor pattern 2, one or more fourth temperature measurement patterns 14 and one or more fifth temperature measurement patterns 15 are locally arranged on the surface of the insulating substrate 1 at a distance from each other on both sides of the straight portion of the line 3 a in the second conductor pattern 3 at locations where it is desired to measure the temperature of the surface of the insulating substrate 1 near the straight portion of the line 3 a.

[0042] Next, we will explain how to use infrared thermography to measure the surface temperatures of the first conductor pattern 2 and the second conductor pattern 3, and the surface temperature of the insulating substrate 1 in the vicinity of the first conductor pattern 2. As a preliminary step, the infrared emissivity of the first temperature measurement pattern 11 to the fifth temperature measurement pattern 15 is set in the infrared thermography.

[0043] Next, the high-frequency circuit mounted on the electric circuit board is operated. Then, high-frequency current flows through the first conductor pattern 2 and the second conductor pattern 3, and heat is generated in each of the first conductor pattern 2 and the second conductor pattern 3 due to conductor loss and dielectric loss. As a result, the surface temperatures of the first conductor pattern 2 and the second conductor pattern 3 rise, and the surface temperatures of the first temperature-measurement pattern 11 to the fifth temperature-measurement pattern 15 also rise.

[0044] By using infrared thermography to capture images of the surfaces of each of the first temperature measurement pattern 11 to the fifth temperature measurement pattern 15, the infrared thermography detects the infrared rays emitted from the surfaces of each of the first temperature measurement pattern 11 to the fifth temperature measurement pattern 15, and the temperature distribution obtained by converting the detected amount of infrared rays into thermal energy is visualized as image information and displayed on a display device.

[0045] In other words, by using infrared thermography to measure the surface temperatures of each of the first temperature measurement pattern 11 to the fifth temperature measurement pattern 15 in a non-contact manner, the surface temperatures of the first conductor pattern 2, the second conductor pattern 3, and the insulating substrate 1 at set positions can be measured in real time with high accuracy.

[0046] Infrared thermography not only displays the measured temperature information as image information, but also stores the measured temperature information as digital data in a storage means, making it possible to obtain the temperature information as data.

[0047] As described above, the electric circuit board according to the first embodiment has conductor patterns 2 and 3, through which high-frequency current flows, formed on the surface of the insulating substrate 1, and temperature measurement patterns 11 to 15, each having an infrared emissivity higher than that of the conductor patterns 2 and 3, provided on the surface of the insulating substrate 1. Therefore, by detecting the infrared rays radiated from the surfaces of the temperature measurement patterns 11 to 15, the surface temperature due to heat generation of the conductor patterns 2 and 3 can be measured with high accuracy.

[0048] The electric circuit board according to the first embodiment has locally arranged solder resist patterns made of either resin or ceramic as the temperature measurement patterns 11 to 15, and therefore does not increase electrical loss to the high-frequency circuit due to the temperature measurement patterns 11 to 15. Furthermore, since the temperature measurement patterns 11 to 15 are formed at a distance on both sides of the conductor patterns 2 and 3, it is possible to avoid the edges of the conductor patterns 2 and 3 where the electric field intensity is high, and therefore the temperature measurement patterns 11 to 15 do not increase electrical loss to the high-frequency circuit.

[0049] The first temperature-measurement pattern 11 can measure with high accuracy the surface temperature of the first conductor pattern 2, which is a concern for heat generation. The second temperature-measurement pattern 12 is formed on the surface of the thin line portion 2b of the first conductor pattern 2, which is a concern for heat generation, so the surface temperature of the thin line portion 2b, which is a concern for heat generation, can be measured with high accuracy. The third temperature-measurement pattern 13 is formed on the surface of the bent portion 3b of the second conductor pattern 3, which is a concern for heat generation, so the surface temperature of the bent portion 3b, which is a concern for heat generation, can be measured with high accuracy. The fourth temperature-measurement pattern 14 and the fifth temperature-measurement pattern 15 can each measure with high accuracy the surface temperature of the insulating substrate 1, which is a concern for heat generation.

[0050] Furthermore, in the case where a problem occurs during use of the electric circuit board according to embodiment 1, the surface temperatures of the conductor patterns 2, 3 and the insulating substrate 1 can be measured in real time in a non-contact manner using an infrared thermograph or an infrared radiation thermometer using the temperature measurement patterns 11 to 15.

[0051] Embodiment 2 An electric circuit board according to embodiment 2 will be described with reference to Figure 3. The electric circuit board according to embodiment 2 is an electric circuit board on which a high-frequency circuit is mounted and in which a conductor pattern 5 having an open stub 6 is formed on the surface of an insulating substrate 1. The electric circuit board according to embodiment 2 includes an insulating substrate 1, a third conductor pattern 5 having an open stub 6, a ground conductor 4, and sixth to ninth temperature measurement patterns 21 to 24.

[0052] A third conductor pattern 5 having an open stub 6 is formed on the front surface of the insulating substrate 1, and a ground conductor 4 is formed on the back surface of the insulating substrate 1. The open stub 6 is a quarter-wave open stub for a high-frequency signal incident on the third conductor pattern 5. The third conductor pattern 5 is a microstrip line formed between the third conductor pattern 5 and the ground conductor 4. The third conductor pattern 5 may form a coplanar line or a differential line.

[0053] The third conductor pattern 5, like the first conductor pattern 2 and the second conductor pattern 3, is made of copper or gold metal and is formed on the surface of the insulating substrate 1 with its metal surface exposed. As shown in Fig. 3, the third conductor pattern 5 has a line 5a with a characteristic impedance of 50 Ω and an open stub 6 extending from the line 5a. The angle between the line 5a and the open stub 6 is 90 degrees. That is, the open stub 6 and the line 5a form a T-shape in plan view.

[0054] The length of the open stub 6 is one-fourth the wavelength of the high-frequency signal transmitted through the third conductor pattern 5. In other words, the length from the intersection 5b of the open stub 6 and the line 5a in the third conductor pattern 5 to the tip of the open stub 6 is one-fourth the wavelength of the high-frequency signal.

[0055] As indicated by arrow B in Fig. 3, a high-frequency signal is incident on the third conductor pattern 5 from the left side of the figure. When the high-frequency signal is incident on the third conductor pattern 5, a high-frequency current caused by the high-frequency signal flows, causing the third conductor pattern 5 to generate heat due to conductor loss and dielectric loss, resulting in a temperature rise. The conductor loss in the third conductor pattern 5 is due to the current amplitude of the high-frequency signal, and the dielectric loss in the third conductor pattern 5 is due to the electric field amplitude (voltage amplitude) of the high-frequency signal.

[0056] Note that the high-frequency signal incident from the left side of the figure is hardly transmitted to the line 5a on the right side of the figure from the intersection 5b between the open stub 6 and the line 5a of the third conductor pattern 5. As a result, almost no heat is generated by the high-frequency signal on the line 5a on the right side of the figure from the intersection 5b.

[0057] Each of the sixth temperature measurement pattern 21 to the ninth temperature measurement pattern 24 is formed by a solder resist pattern made of an insulating material such as resin or ceramic, similar to each of the first temperature measurement pattern 11 to the fifth temperature measurement pattern 15. Each of the sixth temperature measurement pattern 21 to the ninth temperature measurement pattern 24 is formed locally on the surface of the third conductor pattern 5 with the surface of the solder resist exposed.

[0058] The sixth temperature measurement pattern 21 is formed in a rectangular shape on the surface of the tip of the open stub 6, spaced apart from both sides of the open stub 6. That is, the sixth temperature measurement pattern 21 is locally arranged on the inside surface of the tip of the open stub 6 so as to avoid the edges of the open stub 6. When a high-frequency signal is transmitted to the open stub 6, the electric field amplitude (voltage amplitude) of the standing wave due to the high-frequency signal reaches its maximum at the tip of the open stub 6, increasing dielectric loss and raising concerns about heat generation.

[0059] The length of the long side of the sixth temperature-measurement pattern 21 is equal to or longer than the wavelength of infrared light, the minimum spatial resolution of infrared thermography, or the minimum spot diameter of an infrared radiation thermometer, similar to the length of the long side of the first temperature-measurement pattern 11. Optimally, the length is equal to the size of the minimum spatial resolution or the size of the minimum spot diameter. Similarly to the thickness of the first temperature-measurement pattern 11, the thickness of the sixth temperature-measurement pattern 21 is equal to or shorter than several tens of micrometers, preferably equal to or shorter than several micrometers.

[0060] In the open stub 6 in the third conductor pattern 5, the temperature of the open stub 6 increases due to dielectric loss, so temperature measurement in the open stub 6 can be performed with high accuracy by detecting infrared rays emitted from the surface of the sixth temperature measurement pattern 21 using an infrared thermography or an infrared radiation thermometer.

[0061] In this case, since the sixth temperature measurement pattern 21 is formed locally on the surface of the tip of the open stub 6, it does not increase electrical loss, thereby suppressing its effect on high-frequency loss and maintaining the characteristics of the open stub 6 and the high-frequency characteristics of the high-frequency circuit. Furthermore, when a high-frequency current flows through the open stub 6, the electric field strength increases along the side of the tip of the open stub 6, i.e., at the edge. However, since the sixth temperature measurement pattern 21 is formed so as to avoid the edge of the tip of the open stub 6, it does not increase electrical loss to the high-frequency circuit.

[0062] The seventh temperature measurement pattern 22 is formed in a rectangular shape on the surface of the open stub 6 at a position ⅛ of the wavelength of the high-frequency signal transmitted through the third conductor pattern 5, spaced apart from both sides of the open stub 6. That is, the seventh temperature measurement pattern 22 is locally arranged on the inside of the surface of the open stub 6 so as to avoid the edges of the open stub 6. When a high-frequency signal is transmitted to the open stub 6 at a position ⅛ of the wavelength of the high-frequency signal from the tip of the open stub 6, the current amplitude of the standing wave due to the high-frequency signal becomes maximum, resulting in increased conductor loss and heat generation.

[0063] The length of the long side of the seventh temperature-measurement pattern 22 is equal to or longer than the wavelength of infrared light, the minimum spatial resolution of infrared thermography, or the minimum spot diameter of an infrared radiation thermometer, similar to the length of the long side of the first temperature-measurement pattern 11, and is optimally equal to the size of the minimum spatial resolution or the size of the minimum spot diameter. The thickness of the seventh temperature-measurement pattern 22 is equal to or shorter than several tens of μm, preferably equal to or shorter than several μm, similar to the thickness of the first temperature-measurement pattern 11.

[0064] In the open stub 6 in the third conductor pattern 5, the temperature of the open stub 6 increases due to conductor loss, so temperature measurement in the open stub 6 can be performed with high accuracy by detecting infrared rays emitted from the surface of the seventh temperature measurement pattern 22 using an infrared thermography or an infrared radiation thermometer.

[0065] In this case, the seventh temperature measurement pattern 22 is formed locally on the surface at a position 1 / 8 wavelength of the high-frequency signal away from the tip of the open stub 6, so it does not increase electrical loss, thereby suppressing the effect on high-frequency loss and maintaining the characteristics of the open stub 6 and the high-frequency characteristics of the high-frequency circuit. Furthermore, when a high-frequency current flows through the open stub 6, the electric field strength increases along the sides of the open stub 6, i.e., at the edges. However, since the seventh temperature measurement pattern 22 is formed to avoid the edges of the open stub 6, it does not increase electrical loss in the high-frequency circuit.

[0066] The eighth temperature measurement pattern 23 is formed on the surface of the line 5a at the intersection 5b between the open stub 6 and the line 5a of the third conductor pattern 5, at a distance from both sides of the line 5a and the open stub 6, and has an L-shaped planar shape along the sides that form the interior angle (hereinafter simply referred to as the interior angle) between the line 5a and the open stub 6, through which a high-frequency signal is incident on the open stub 6. The eighth temperature measurement pattern 23 is locally arranged inside the interior angle so as to avoid the edges of the line 5a and the open stub 6 around the intersection 5b.

[0067] The position of intersection 5b is a quarter (two-eighths) of the wavelength of the high-frequency signal away from the tip of open stub 6, and when a high-frequency signal is transmitted to open stub 6, the electric field amplitude of the standing wave due to the high-frequency signal becomes maximum at line 5a at a position a quarter of the wavelength of the high-frequency signal away from the tip of open stub 6, resulting in increased dielectric loss and the risk of heat generation.

[0068] The length of the long side of the eighth temperature measurement pattern 23, like the length of the long side of the first temperature measurement pattern 11, is equal to or longer than the wavelength of infrared light, the minimum spatial resolution of infrared thermography, or the minimum spot diameter of an infrared radiation thermometer, and is optimally equal to the size of the minimum spatial resolution or the size of the minimum spot diameter. In the second embodiment, the long side of the eighth temperature measurement pattern 23 is an L-shaped portion. Similarly to the thickness of the first temperature measurement pattern 11, the thickness of the eighth temperature measurement pattern 23 is equal to or shorter than several tens of μm, preferably equal to or shorter than several μm.

[0069] In the third conductor pattern 5, the temperature of the line 5a at the intersection 5b where the temperature becomes high due to dielectric loss can be measured with high precision by detecting infrared rays emitted from the surface of the eighth temperature measurement pattern 23 using an infrared thermography or an infrared radiation thermometer.

[0070] In this case, the eighth temperature-measuring pattern 23 is formed locally on the surface of the line 5a at the position of the intersection 5b, so it does not increase electrical loss, thereby suppressing the effect on high-frequency loss and maintaining the high-frequency characteristics of the high-frequency circuit. Moreover, when a high-frequency current flows through the third conductor pattern 5, the eighth temperature-measuring pattern 23 is formed on the inner corner side, avoiding the edge, so it does not increase electrical loss in the high-frequency circuit.

[0071] The ninth temperature measurement pattern 24 is formed in a rectangular shape on both sides of the line 5a at a position one-eighth of the wavelength of the high-frequency signal away from the intersection 5b between the open stub 6 and the line 5a of the third conductor pattern 5 on the side where the high-frequency signal is incident. That is, the ninth temperature measurement pattern 24 is locally arranged inside the surface of the third conductor pattern 5 so as to avoid the edge of the third conductor pattern 5 at a position three-eighths of the wavelength away from the tip of the open stub 6 in the direction where the high-frequency signal is incident on the third conductor pattern 5. When a high-frequency signal is transmitted to the third conductor pattern 5 at the position three-eighths of the wavelength of the high-frequency signal from the tip of the open stub 6, the current amplitude of the standing wave due to the high-frequency signal becomes maximum, resulting in increased conductor loss and concerns about heat generation.

[0072] The length of the long side of the ninth temperature-measurement pattern 24 is equal to or longer than the wavelength of infrared light, the minimum spatial resolution of infrared thermography, or the minimum spot diameter of an infrared radiation thermometer, similar to the length of the long side of the first temperature-measurement pattern 11, and is optimally equal to the size of the minimum spatial resolution or the size of the minimum spot diameter. The thickness of the ninth temperature-measurement pattern 24 is equal to or shorter than several tens of μm, preferably equal to or shorter than several μm, similar to the thickness of the first temperature-measurement pattern 11.

[0073] In the third conductor pattern 5, the temperature of the line 5a, where the temperature increases due to conductor loss, can be measured with high accuracy by detecting infrared rays emitted from the surface of the ninth temperature measurement pattern 24 using an infrared thermography or an infrared radiation thermometer.

[0074] In this case, the ninth temperature measurement pattern 24 is formed locally on the surface at a position three-eighths of the wavelength of the high-frequency signal from the tip of the open stub 6, so that it does not increase electrical loss, thereby suppressing the effect on high-frequency loss and maintaining the high-frequency characteristics of the high-frequency circuit. Furthermore, when a high-frequency current flows through the line 5a, the electric field strength increases along the sides of the line 5a, i.e., at the edges. Therefore, the ninth temperature measurement pattern 24 is formed so as to avoid the edges of the line 5a, so that it does not increase electrical loss in the high-frequency circuit.

[0075] In the electric circuit board of embodiment 2, temperature measurement patterns 21 to 24 are locally formed on the surface of the tip of the open stub 6 and on the surface of the third conductor pattern 5 at positions spaced one-eighth of the wavelength of the high-frequency signal from the tip of the open stub 6 toward the side where the high-frequency signal is incident.

[0076] In FIG. 3 , temperature measurement patterns are not shown on the surface of the insulating substrate 1 at a distance along each of both sides of the line 5 a in the third conductor pattern 5 on the side where the high-frequency signal is incident from the intersection 5 b between the open stub 6 and the line 5 a in the third conductor pattern 5. However, similar to the fourth temperature measurement pattern 14 and the fifth temperature measurement pattern 15, temperature measurement patterns are locally arranged on the surface of the insulating substrate 1 at a position ⅛ of the wavelength of the high-frequency signal away from the intersection 5 b between the open stub 6 and the line 5 a in the third conductor pattern 5 on the side where the high-frequency signal is incident.

[0077] Measurement of the surface temperature of the third conductor pattern 5 using infrared thermography is performed in the same manner as measurement of the surface temperatures of the first conductor pattern 2 and the second conductor pattern 3. That is, the high-frequency circuit mounted on the electric circuit board is operated, and images of the surfaces of the sixth temperature-measurement pattern 21 to the ninth temperature-measurement pattern 24 are taken using infrared thermography.

[0078] The infrared thermography detects infrared rays emitted from the surfaces of the sixth to ninth temperature measurement patterns 21 to 24, and visualizes the temperature distribution by converting the detected amount of infrared rays into thermal energy and displaying it on a display device. As a result, the surface temperature of a set position on the third conductor pattern 5 can be measured with high accuracy in real time without contact.

[0079] As described above, the electric circuit board according to the second embodiment has a conductor pattern 5 having an open stub 6 of a quarter wavelength of a high-frequency signal formed on the surface of an insulating substrate 1, and locally includes temperature measurement patterns 21 to 24, each having an infrared emissivity higher than that of the third conductor pattern 5, on the surface of the tip of the open stub 6 and on the surface of the third conductor pattern 5 at a position 1 / 8 of the wavelength of the high-frequency signal away from the tip of the open stub 6 on the side where the high-frequency signal is incident. Therefore, by detecting infrared rays radiated from the surfaces of the temperature measurement patterns 21 to 24, the surface temperature due to heat generation of the third conductor pattern 5 including the open stub 6 can be measured with high accuracy.

[0080] Moreover, as explained in the first embodiment, the electric circuit board according to the second embodiment can also measure the surface temperature of the third conductor pattern 5, including the open stub 6, which is likely to generate heat, with high accuracy, without increasing the electrical loss to the high-frequency circuit due to the temperature measurement patterns 21 to 24, as in the electric circuit board according to the first embodiment. Furthermore, even if a problem occurs during use of the electric circuit board according to the second embodiment, the surface temperature of the third conductor pattern 5 can be measured in real time in a non-contact manner using an infrared thermograph or an infrared radiation thermometer, using the temperature measurement patterns 21 to 24.

[0081] In the electric circuit board according to the second embodiment, an electric circuit board is shown in which a conductor pattern 5 having a quarter-wave open stub 6 for a high-frequency signal is formed on the surface of an insulating substrate 1. However, in an electric circuit board that utilizes a standing wave on a high-frequency circuit such as a short stub or a resonator, a temperature measurement pattern may be formed on the surface of a conductor pattern where the voltage amplitude or current amplitude of the standing wave is maximized.

[0082] In short, in an electric circuit board in which a standing wave due to a high frequency signal appears on a conductor pattern, by forming a temperature measurement pattern on the surface of a portion of the conductor pattern where the current amplitude or voltage amplitude of the standing wave due to the high frequency signal appearing on the conductor pattern is large, the surface temperature of the conductor pattern, which is a concern for heat generation, can be measured with high accuracy without increasing the electrical loss to the high frequency circuit due to the temperature measurement pattern.

[0083] It should be noted that the embodiments may be freely combined, or any of the components in each embodiment may be modified, or any of the components in each embodiment may be omitted.

[0084] The electric circuit board according to the present disclosure is suitable for use as an electric circuit board incorporating a high-frequency circuit.

[0085] 1 insulating substrate, 2 first conductor pattern, 2a line, 2b thin line portion, 3 second conductor pattern, 3a line, 3b bent portion, 4 ground conductor, 5 conductor pattern, 6 open stub, 11-15 first temperature measurement pattern to fifth temperature measurement pattern, 21-24 sixth temperature measurement pattern to ninth temperature measurement pattern.

Claims

1. An electric circuit board comprising: an insulating substrate; a conductor pattern formed on a surface of the insulating substrate and onto which a high-frequency signal is incident; and a temperature measurement pattern formed on the surface of the insulating substrate and having an infrared emissivity higher than that of the conductor pattern.

2. The electric circuit board according to claim 1, wherein the temperature measurement pattern is a solder resist pattern made of either resin or ceramics.

3. The electric circuit board according to claim 1, wherein the formation of the temperature-measuring pattern on the surface of the insulating substrate is such that a first temperature-measuring pattern is formed on the surface of the conductor pattern at a distance from both sides of the conductor pattern.

4. The electric circuit board according to claim 3, wherein the position of the first temperature-measuring pattern formed on the surface of the insulating substrate is a portion of the conductor pattern having a large thermal resistance or a portion of the conductor pattern having a large loss density.

5. The electric circuit board according to claim 1, wherein the conductor pattern has a thin line portion having a narrow line width, and the formation of the temperature measurement pattern on the surface of the insulating substrate is such that a second temperature measurement pattern is formed on the surface of the thin line portion of the conductor pattern at a distance from both sides of the thin line portion of the conductor pattern.

6. The electric circuit board according to claim 1, wherein the conductor pattern has a bent portion where a line is bent, and the formation of the temperature measurement pattern on the surface of the insulating substrate is such that a third temperature measurement pattern is formed on the surface of the bent portion of the conductor pattern at a distance from both sides of the bent portion of the conductor pattern.

7. The electric circuit board according to claim 6, wherein said third temperature-measuring pattern is positioned on the inner corner side of a bent portion of said conductor pattern.

8. The electric circuit board according to claim 1, wherein the formation of the temperature-measuring pattern on the surface of the insulating substrate is such that a fourth temperature-measuring pattern is formed on the surface of the insulating substrate at a distance along one side of the conductor pattern.

9. An electric circuit board as described in claim 8, wherein the position of the fourth temperature measurement pattern formed on the surface of the insulating substrate is a position spaced apart along one side of a portion of the conductor pattern having high thermal resistance or high loss density.

10. The electric circuit board according to claim 1, wherein the conductor pattern has an open stub, and the formation of the temperature measurement patterns on the surface of the insulating substrate is such that a sixth temperature measurement pattern is formed on the surface of the tip of the open stub, and a seventh temperature measurement pattern is formed on the surface of the open stub at a position that is 1 / 8 of the wavelength of the high frequency signal that is applied from the tip of the open stub to the conductor pattern.

11. The electric circuit board according to claim 10, wherein the formation of the temperature measurement pattern on the surface of the insulating substrate further comprises the formation of an eighth temperature measurement pattern on the surface of the line at the intersection between the open stub and the line in the conductor pattern.

12. The electric circuit board according to claim 11, wherein the formation of the temperature measurement patterns on the surface of the insulating substrate further comprises the formation of a ninth temperature measurement pattern on the surface of the line in the conductor pattern at a position one-eighth of the wavelength of the high frequency signal on the side where the high frequency signal is incident from the intersection of the open stub and the line in the conductor pattern.

13. An electric circuit board as described in claim 1, in which a standing wave due to a high frequency signal appears in the conductor pattern, and the position at which the temperature measurement pattern is formed on the surface of the insulating substrate is on the surface of a portion of the conductor pattern where the current amplitude or voltage amplitude of the standing wave due to the high frequency signal appearing on the conductor pattern is large.

14. The electric circuit board according to any one of claims 1 to 13, wherein the length of the temperature measurement pattern is equal to or longer than the wavelength of infrared light.

15. An electric circuit board according to any one of claims 1 to 13, wherein the length of the temperature measurement pattern is equal to or greater than the minimum spatial resolution of an infrared thermograph that detects temperature by detecting infrared rays emitted from the surface of the temperature measurement pattern.

16. An electric circuit board according to any one of claims 1 to 13, wherein the length of the temperature measurement pattern is the minimum spatial resolution of an infrared thermograph which detects temperature by detecting infrared rays emitted from the surface of the temperature measurement pattern.

17. An electric circuit board as claimed in any one of claims 1 to 13, wherein the length of the temperature measurement pattern is equal to or greater than the minimum spot diameter of an infrared radiation thermometer that detects temperature by detecting infrared rays emitted from the surface of the temperature measurement pattern.

18. An electric circuit board according to any one of claims 1 to 13, wherein the length of the temperature measurement pattern is the length of the minimum spot diameter of an infrared radiation thermometer that detects the temperature by detecting infrared rays emitted from the surface of the temperature measurement pattern.

19. An electric circuit board according to any one of claims 1 to 13, further comprising a ground conductor formed on a rear surface of the insulating substrate, the conductor pattern facing the ground conductor and constituting a microstrip line.

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