A structure for long-distance signal transmission based on thick film

Abstract

A structure for long-distance signal transmission based on thick film, comprising: a first layer circuit, a second layer circuit, a third layer circuit, a fourth layer circuit, and a ceramic substrate, the number of which is at least three, including a first ceramic substrate, a second ceramic substrate and a third ceramic substrate, and the first ceramic substrate is located between the first layer circuit and the second layer circuit, the second ceramic substrate is located between the second layer circuit and the third layer circuit, and the third ceramic substrate is located between the third layer circuit and the fourth layer circuit. The present invention is conducive to the miniaturized integrated design of the circuit system. Since the coaxial line is a three-dimensional structure, it cannot be directly used in an integrated structure based on a thick film circuit. By adopting this structure, and by means of thick film circuit multilayers and metallized vias, a microstrip line with a two-dimensional planar structure can be equivalent to a coaxial line with a three-dimensional structure. While ensuring the transmission effect, the cross-sectional size of the circuit can also be reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of signal transmission, and in particular to a structure for long-distance signal transmission based on thick films. Background Art

[0002] At present, the signal power emitted by radar, satellite communication and other fields is getting bigger and bigger, but the overall size is getting smaller and smaller, so the integration is getting higher and higher, which inevitably leads to more and more complex circuits. Various signal transmission lines are required in the circuit. Generally, microstrip lines are often used as signal transmission lines in the radio frequency band. However, due to the limited circuit size and complex structure, the transmission lines need to be carefully arranged to meet the purpose of transmitting signals without affecting the performance of the overall circuit.

[0003] Microstrip lines are metal conductive strip structures exposed on the surface of dielectric substrates. In the radio frequency band, microstrip lines, while acting as signal transmission lines, also generate spatial radiation, bringing crosstalk signals and causing electromagnetic compatibility problems. In addition, if the signal transmission distance on the microstrip line is too long, its attenuation will increase significantly.

[0004] As a signal transmission line, the coaxial line has a structure of inner and outer conductors, so the transmission signal is limited to the inner and outer conductors for transmission, which does not cause energy loss or spatial radiation. However, compared with microstrip transmission lines, the coaxial line has a three-dimensional structure, which increases the cross-sectional size of the entire circuit. In addition, the coaxial transmission line and the microstrip structure circuit require three-dimensional welding, which increases the difficulty of the assembly process. At the same time, this link also reduces the reliability of the product. The most important thing is that the coaxial line cannot be packaged in the circuit. Summary of the invention

[0005] The present invention provides a structure for long-distance signal transmission based on thick film to solve the shortcomings of the above-mentioned prior art. By utilizing the characteristics of the thick film circuit multilayer structure and metallized vias, the planar structure is equivalent to the three-dimensional structure of the coaxial transmission line, and the microstrip structure is used to realize the function of the coaxial transmission line, which has strong practicality.

[0006] In order to achieve the purpose of the present invention, the following technologies are proposed:

[0007] A structure for long-distance signal transmission based on thick film, comprising:

[0008] A first layer circuit has at least one pair of first microstrip lines, inner ends of the first microstrip lines are each provided with a first via hole, and the first layer circuit is used for input or output of radio frequency signals;

[0009] The second layer circuit has at least one pair of second vias, two rows of third vias are arranged on both sides of the second vias, the number of the second vias is the same as that of the first vias, the second vias correspond to the first vias one by one, and the second vias are connected to the corresponding first vias;

[0010] A third layer circuit has at least one second microstrip line, both ends of the second microstrip line are provided with fourth vias, both sides of the second microstrip line are provided with a row of fifth vias, the number of the fourth vias is the same as that of the second vias, and the fourth vias correspond to the second vias one-to-one, the number of the fifth vias is the same as that of the third vias, and the fifth vias correspond to the third vias one-to-one, and the fifth vias are connected to the corresponding third vias;

[0011] A fourth layer circuit has two rows of sixth vias, the number of the sixth vias is the same as the number of the fifth vias, and the sixth vias correspond to the fifth vias one by one, and the sixth vias are connected to the corresponding fifth vias;

[0012] There are at least three ceramic substrates, including a first ceramic substrate, a second ceramic substrate and a third ceramic substrate. The first ceramic substrate is located between the first layer circuit and the second layer circuit, the second ceramic substrate is located between the second layer circuit and the third layer circuit, and the third ceramic substrate is located between the third layer circuit and the fourth layer circuit.

[0013] Furthermore, at least one pair of first metal vias is provided on the first ceramic substrate;

[0014] At least one pair of second metal vias is provided on the second ceramic substrate, and a row of third metal vias is provided on both sides of the second metal vias.

[0015] At least two rows of fourth metal vias are provided on the third ceramic substrate;

[0016] The number of the first metal vias is the same as that of the first vias, and the first metal vias correspond to the first vias one by one, and the first metal vias are connected to the corresponding first vias;

[0017] The number of the second metal vias is the same as that of the second vias, and the second metal vias correspond to the second vias one by one, and the second metal vias are connected to the corresponding second vias;

[0018] The number of the third metal vias is the same as that of the third vias, and the third metal vias correspond to the third vias one by one, and the third metal vias are connected to the corresponding third vias;

[0019] The number of the fourth metal vias is the same as that of the sixth vias, and the fourth metal vias correspond to the sixth vias one-to-one, and the fourth metal vias are connected to the corresponding sixth vias.

[0020] Furthermore, both ends of the first metal via and the second metal via are tapered structures;

[0021] Both ends of the first metal via and the second metal via are large ends.

[0022] Furthermore, the height of the first metal via and the second metal via conical structure is one quarter of the thickness of the first ceramic substrate and the second ceramic substrate.

[0023] The advantages of the above technical solution are:

[0024] 1. For any RF signal transmission over a long distance or for microstrip lines that may cross or jumper in the circuit layout, this structure can be applied to arrange the transmission lines on different layers to avoid the problems of the prior art and achieve a compact layout of the surface circuit without affecting the performance.

[0025] 2. In order to maintain good connection of each metal via and offset the misalignment problem caused by shrinkage during the firing process of the thick film substrate, a conical structure step design is adopted on the upper and lower sides of the ceramic substrate to increase the area of ​​each via and the connection between each metal via to ensure a good connection effect.

[0026] 3. High-frequency radio frequency signals will radiate into space during transmission, and reflect and oscillate back and forth in the miniaturized system of metallized packaging. In addition to bringing interference noise signals, they are also enhanced due to phase superposition, and there is also a risk of burning sensitive components. However, this structure has a reasonable structural design, so that when the structure is in use, there will be no spatial radiation, thereby avoiding the problem of electromagnetic interference.

[0027] 4. The signal transmission loss of the present invention will be greatly reduced. By setting the fifth via hole on the third layer circuit where the second microstrip line is located, and setting the second ceramic substrate and the third ceramic substrate on the upper and lower sides of the third layer circuit, and setting the second layer circuit and the fourth layer circuit on the upper side of the second ceramic substrate and the lower side of the third ceramic substrate respectively, and the third via hole, the third metal via hole, the fifth via hole, the fourth metal via hole and the sixth via hole set on the above components together constitute a closed metal cavity, so that the present structure is equivalent to a coaxial line, and when the coaxial line transmits radio frequency signals, except for the necessary dielectric attenuation, no radiation attenuation will occur, and low-loss transmission of long-distance signals can be performed.

[0028] 5. The present invention is conducive to the miniaturized integrated design of the circuit system. Since the coaxial line is a three-dimensional structure, it cannot be directly used in the integrated structure based on the thick film circuit. However, by adopting the present structure and the thick film circuit multilayer and metallized vias, the microstrip line with a two-dimensional planar structure can be equivalent to a coaxial line with a three-dimensional structure. Under the premise of ensuring the transmission effect, the cross-sectional size of the circuit can also be reduced.

[0029] 6. The present invention is suitable for high-power signal transmission in thick film circuits. Existing exposed microstrip lines may break down and spark when transmitting high-power signals, thus causing the risk of burning the circuit. The second microstrip line involved in the present invention is equivalent to the inner conductor of the coaxial line, and each metallized via and the second layer circuit and the fourth layer circuit together constitute the outer conductor of the coaxial line. These structures are arranged on each ceramic substrate, and the breakdown field strength threshold of the ceramic substrate is much greater than that of air. Therefore, this structure can withstand the transmission of higher power signals. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention will be further described in detail below with reference to the accompanying drawings.

[0031] Figure 1 A three-dimensional structural diagram of the present invention is shown.

[0032] Figure 2 An exploded perspective view of the present invention is shown.

[0033] Figure 3 A comparison curve diagram of the transmission effect between the present invention and the coaxial line is shown.

[0034] Figure 4 A three-dimensional structural diagram of the coaxial line is shown. DETAILED DESCRIPTION

[0035] Example 1

[0036] like Figure 3 As shown, the coaxial line is composed of inner and outer conductors, and the inner and outer conductors are filled with a medium or air. The currents on the inner and outer conductors are equal in magnitude and opposite in direction. According to Ampere's loop theorem, the external magnetic field intensity of the outer conductor is 0. According to Poynting's theorem, the electromagnetic energy flow density shows that there is no electromagnetic energy distribution outside the outer conductor. In other words, the coaxial line will not radiate energy when transmitting electromagnetic signals, and the signal is always transmitted forward between the inner and outer conductors. At the same time, according to the medium filled inside, the coaxial line is also suitable for long-distance transmission of high-power signals. Since the coaxial line is a three-dimensional structure, it is not suitable for use in thick film integrated circuits.

[0037] Example 2

[0038] like Figure 1~Figure 2As shown, a structure for long-distance signal transmission based on thick film includes: a first layer circuit 1, on which there is at least a pair of first microstrip lines 10, and the inner ends of the first microstrip lines 10 are each provided with a first via 11, and the first layer circuit 1 is used for input or output of radio frequency signals, and the input of the radio frequency signal can be an external input or a signal output by a local circuit. The output signal of the radio frequency signal can be directly connected to the output end of the system, or can be connected to a subsequent local circuit as an input signal.

[0039] The second layer circuit 2 has at least one pair of second vias 20, and two rows of third vias 21 are provided on both sides of the second vias 20. The number of the second vias 20 is the same as that of the first vias 11, and the second vias 20 correspond to the first vias 11 one by one, and the second vias 20 are connected to the corresponding first vias 11.

[0040] The third layer circuit 3 has at least one second microstrip line 30, and both ends of the second microstrip line 30 are provided with fourth vias 31, and both sides of the second microstrip line 30 are provided with a row of fifth vias 32, the number of the fourth vias 31 is the same as the second vias 20, and there is a one-to-one correspondence between the fourth vias 31 and the second vias 20, the number of the fifth vias 32 is the same as the third vias 21, and there is a one-to-one correspondence between the fifth vias 32 and the third vias 21, and the fifth vias 32 are connected to the corresponding third vias 21. The second microstrip line 30 on the third layer circuit 3 is equivalent to the inner conductor in the coaxial line.

[0041] The fourth layer circuit 4 has two rows of sixth vias 40 . The number of the sixth vias 40 is the same as that of the fifth vias 32 . There is a one-to-one correspondence between the sixth vias 40 and the fifth vias 32 . The sixth vias 40 are connected to the corresponding fifth vias 32 .

[0042] There are at least three ceramic substrates 5, which include a first ceramic substrate 50, a second ceramic substrate 51 and a third ceramic substrate 52, and the first ceramic substrate 50 is located between the first layer circuit 1 and the second layer circuit 2, the second ceramic substrate 51 is located between the second layer circuit 2 and the third layer circuit 3, and the third ceramic substrate 52 is located between the third layer circuit 3 and the fourth layer circuit 4.

[0043] The second layer circuit 2 , the third layer circuit 3 and the fourth layer circuit 4 are a metal layer, and the above metal layers are all attached to the ceramic substrate 5 .

[0044] The first ceramic substrate 50 is provided with at least one pair of first metal vias 500. The second ceramic substrate 51 is provided with at least one pair of second metal vias 510, and a row of third metal vias 511 is provided on both sides of the second metal vias 510. The third ceramic substrate 52 is provided with at least two rows of fourth metal vias 520.

[0045] The number of the first metal vias 500 is the same as that of the first vias 11, and the first metal vias 500 correspond to the first vias 11 one-to-one, and the first metal vias 500 are connected to the corresponding first vias 11. The number of the second metal vias 510 is the same as that of the second vias 20, and the second metal vias 510 correspond to the second vias 20 one-to-one, and the second metal vias 510 are connected to the corresponding second vias 20. The number of the third metal vias 511 is the same as that of the third vias 21, and the third metal vias 511 correspond to the third vias 21 one-to-one, and the third metal vias 511 are connected to the corresponding third vias 21. The number of the fourth metal vias 520 is the same as that of the sixth vias 40, and the fourth metal vias 520 correspond to the sixth vias 40 one-to-one, and the fourth metal vias 520 are connected to the corresponding sixth vias 40. And the spacing between the two rows of fifth vias 32 is less than a quarter wavelength of the signal transmitted by the second microstrip line 30. This design enables the third metal via 511 and the fourth metal via 520 to function as a fully reflective good conductor for the RF signal on the second microstrip line 30, and the gaps between the sixth via 40, the fifth via 32 and the third via 21 will not cause signal radiation leakage. Moreover, the structure formed by the third via 21, the third metal via 511, the fifth via 32 and the fourth metal via 520 and the second layer circuit 2 and the fourth layer circuit 4 is equivalent to the outer conductor of the coaxial line, so it can be seen that the structure adopted in this embodiment can realize the transmission signal with low loss in the closed space between the second microstrip line 30 and the third via 21, the third metal via 511, the fifth via 32 and the fourth metal via 520 and the second layer circuit 2 and the fourth layer circuit 4 for long-distance transmission.

[0046] Definition S 11 is the reflected voltage U at the signal incident port r and the incident voltage U i The decibel value of the ratio can reflect the reflection of the incident port. Generally speaking, when dB is greater, it means that the reflection is smaller, and the signal can be well transmitted between the two connection ports. In the same frequency band, the transmission effect of Example 1 and Example 2 is as follows: Figure 3 shown.

[0047] In the actual firing process, the via connection in the thick film circuit has a very small aperture. At the same time, due to the uneven heating of each layer of ceramic material, the shrinkage is inconsistent, which may cause the various vias to not be well connected, so that a good connection cannot be achieved. When the RF signal is transmitted, it is easy to have the problem of transmission at each connection, which affects the transmission effect of the RF signal. In order to achieve a good connection, both ends of the first metal via 500 and the second metal via 510 are tapered structures, and both ends of the first metal via 500 and the second metal via 510 are large ends. The height of the tapered structure of the first metal via 500 and the second metal via 510 is one-fourth of the thickness of the first ceramic substrate 50 and the second ceramic substrate 51.

[0048] It can be seen from the figure that, compared with the transmission effects of Example 1 and Example 2, the reflection of Example 2 in the low frequency band of 2GHz-5GHz is lower than that of the coaxial line, and its reflection in the high frequency band of 5GHz-6GHz is higher than that of the coaxial line. Although there are differences in the transmission conditions between the two, the difference in reflection conditions is small. Therefore, it can be seen that Example 1 is equivalent to Example 2.

[0049] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A structure for long-distance signal transmission based on thick film, characterized in that: include: A first layer circuit (1) having at least one pair of first microstrip lines (10) thereon, wherein the inner ends of the first microstrip lines (10) are each provided with a first via hole (11), and the first layer circuit (1) is used for inputting or outputting radio frequency signals; A second layer circuit (2) having at least one pair of second via holes (20), two rows of third via holes (21) being provided on both sides of the second via holes (20), the number of the second via holes (20) being the same as that of the first via holes (11), the second via holes (20) corresponding to the first via holes (11) one-to-one, and the second via holes (20) being connected to the corresponding first via holes (11); A third layer circuit (3) having at least one second microstrip line (30), fourth vias (31) being provided at both ends of the second microstrip line (30), a row of fifth vias (32) being provided at both sides of the second microstrip line (30), the number of the fourth vias (31) being the same as the number of the second vias (20), and the fourth vias (31) and the second vias (20) being in one-to-one correspondence, the number of the fifth vias (32) being the same as the number of the third vias (21), and the fifth vias (32) and the third vias (21) being in one-to-one correspondence, and the fifth vias (32) being connected to the corresponding third vias (21); A fourth layer circuit (4) having two rows of sixth vias (40), the number of the sixth vias (40) being the same as the number of the fifth vias (32), and the sixth vias (40) and the fifth vias (32) being in one-to-one correspondence, and the sixth vias (40) being connected to the corresponding fifth vias (32); The ceramic substrates (5) are at least three in number and include a first ceramic substrate (50), a second ceramic substrate (51) and a third ceramic substrate (52); the first ceramic substrate (50) is located between the first layer circuit (1) and the second layer circuit (2), the second ceramic substrate (51) is located between the second layer circuit (2) and the third layer circuit (3), and the third ceramic substrate (52) is located between the third layer circuit (3) and the fourth layer circuit (4).

2. The structure for long-distance signal transmission based on thick film according to claim 1, characterized in that: At least one pair of first metal vias (500) is provided on the first ceramic substrate (50); At least one pair of second metal vias (510) is provided on the second ceramic substrate (51), and a row of third metal vias (511) is provided on both sides of the second metal vias (510). At least two rows of fourth metal vias (520) are provided on the third ceramic substrate (52); The number of the first metal vias (500) is the same as that of the first vias (11), and the first metal vias (500) correspond to the first vias (11) one by one, and the first metal vias (500) are connected to the corresponding first vias (11); The number of the second metal vias (510) is the same as that of the second vias (20), and the second metal vias (510) correspond to the second vias (20) one by one, and the second metal vias (510) are in communication with the corresponding second vias (20); The number of the third metal vias (511) is the same as that of the third vias (21), and the third metal vias (511) correspond to the third vias (21) one by one, and the third metal vias (511) are connected to the corresponding third vias (21); The number of the fourth metal vias (520) is consistent with that of the sixth vias (40), and the fourth metal vias (520) correspond to the sixth vias (40) one by one, and the fourth metal vias (520) are connected to the corresponding sixth vias (40).

3. The structure for long-distance signal transmission based on thick film according to claim 2, characterized in that: Both ends of the first metal via (500) and the second metal via (510) are tapered structures; Both ends of the first metal via (500) and the second metal via (510) are large ends.

4. The structure for long-distance signal transmission based on thick film according to claim 3, characterized in that: The height of the conical structures of the first metal via (500) and the second metal via (510) is one quarter of the thickness of the first ceramic substrate (50) and the second ceramic substrate (51).

5. The structure for long-distance signal transmission based on thick film according to claim 1, characterized in that: The spacing between the two rows of fifth via holes (32) is smaller than a quarter wavelength of a signal transmitted by the second microstrip line (30).

Images