Embedded ceramic microfilter based on multilayer film

Abstract

The invention discloses an embedded ceramic microfilter based on a multilayer film, which comprises a resonator, the resonator comprises a multilayer dielectric structure and a metal structure, and two taps are respectively connected with two ends of the resonator through microstrip lines. A 1 / 4 wavelength stepped impedance resonator principle is adopted to carry out miniaturization design on a filter resonator, cross coupling is introduced, a 1 / 4 wavelength short-circuit microstrip line filter is improved, a microstrip line resonator is improved into a strip line resonator, the grounding distance is increased, the plane size of the resonator can be indirectly reduced, the resonator is further miniaturized, and the size of the filter is reduced. Compared with a filter chip, the tapped feed replaces gold wire bonding, so that the process difficulty and the processing cost are reduced, the signal transmission efficiency is improved, the filter is short in design and production period, a module can be directly connected with other substrates for use, and the flexibility is high.

Description

Technical Field

[0001] The invention relates to the technical field of filters, and in particular to an embedded ceramic micro filter based on a multi-layer film. Background Art

[0002] The ceramic DPC (Dielectric Polymer Composite) film process is an advanced technology that combines the advantages of ceramic materials and polymer materials. It is used to prepare system modules that require low dielectric constants and good mechanical properties. Low dielectric constant, due to the low dielectric constant of the dielectric PI, can effectively enhance the uniform distribution of the electric field and reduce the phenomenon of excessive concentration of local electric fields, thereby improving the stability of the film under high voltage. The ceramic material itself has good thermal stability, and the polymer provides a certain thermal buffering effect in the composite material, so that the DPC film can still maintain excellent electrical and mechanical properties at higher temperatures. Its high reliability and compact design advantages are often used in module designs such as antennas, radio frequency, and passive devices.

[0003] The RF microwave components and modules that can be designed and produced based on ceramic DPC film technology include filters, power dividers, antennas, couplers, receiving front-end modules, etc. When used in multi-layer integrated design, they have many advantages in wiring line width and line spacing, low impedance metallization, diversity of design changes and high-frequency performance.

[0004] As modern electronic devices continue to develop towards miniaturization and high frequency, the application of miniaturized electronic devices has become a future trend. In the field of radio frequency communications, communication products have more and more functions, and available spectrum resources are particularly important. At this time, filters of various frequency bands are needed to separate different signals. Therefore, designing broadband miniaturized filter modules in high frequency bands has certain practical significance.

[0005] Currently, most high-frequency filters used in ceramic modules use chips to achieve bandpass filtering functions, which results in a large filter size and cannot be miniaturized. Summary of the invention

[0006] The technical problem to be solved by the present invention is how to provide an embedded ceramic micro filter based on a multi-layer film with simple manufacturing process, high signal transmission efficiency and small volume.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is: an embedded ceramic microfilter based on a multilayer thin film, including two taps and a resonator, the resonator including a multilayer dielectric structure and a metal structure, the two taps are respectively connected to the corresponding microstrip lines on the resonator, so that the taps and the resonator are combined together to form the filter.

[0008] A further technical solution is that the multilayer dielectric structure includes a first PI dielectric layer located at the bottom layer, a DPC ceramic dielectric layer is formed on the upper side of the first PI dielectric layer, a second PI dielectric layer, a third PI dielectric layer and a fourth PI dielectric layer are sequentially arranged on the upper surface of the DPC ceramic dielectric layer from bottom to top, the lower surface of the first PI dielectric layer is covered by a metal layer, a first rectangular ring metal layer is formed between the first PI dielectric layer and the DPC ceramic dielectric layer, a second rectangular ring metal layer is formed between the second PI dielectric layer and the DPC ceramic dielectric layer, the first rectangular ring metal layer and the second rectangular ring metal layer are overlapped in a vertical direction, a rectangular metal layer is formed on the left and right sides between the second PI dielectric layer and the third PI dielectric layer, a rectangular metal layer is formed on the left and right sides between the third PI dielectric layer and the fourth PI dielectric layer, a rectangular metal layer is formed on the left and right sides of the upper surface of the fourth PI dielectric layer, and the rectangular metal layer overlaps the left and right parts of the second rectangular ring metal layer in the vertical direction.

[0009] A further technical solution is that: the left end of the first microstrip line is connected to the first resonant metal line through a first signal metallized through hole, the first resonant metal line is located on the upper surface of the first PI dielectric layer enclosed by the first rectangular ring metal layer, and the right end of the first microstrip line is connected to the metal layer of the bottom layer of the first PI dielectric layer through a second signal metallized through hole;

[0010] The right end of the second microstrip line is connected to the second resonant metal line through a third signal metallized through hole, the second resonant metal line is located on the upper surface of the first PI dielectric layer enclosed by the first rectangular ring metal layer, and the left end of the second microstrip line is connected to the metal layer of the bottom layer of the first PI dielectric layer through a fourth signal metallized through hole;

[0011] The right end of the third microstrip line is connected to the third resonant metal line through a fifth signal metallized through hole, the third resonant metal line is located on the upper surface of the first PI dielectric layer surrounded by the first rectangular ring metal layer, and the left end of the third microstrip line is connected to the metal layer of the bottom layer of the first PI dielectric layer through a sixth signal metallized through hole;

[0012] The left end of the fourth microstrip line is connected to the fourth resonant metal line through the seventh signal metallization through hole, the fourth resonant metal line is located on the upper surface of the first PI dielectric layer surrounded by the first rectangular ring metal layer, and the right end of the fourth microstrip line is connected to the metal layer of the bottom layer of the first PI dielectric layer through the eighth signal metallization through hole;

[0013] The left end of the fifth microstrip line is connected to the fifth resonant metal line through a ninth signal metallized through hole, the fifth resonant metal line is located on the upper surface of the first PI dielectric layer enclosed by the first rectangular ring metal layer, and the right end of the fifth microstrip line is connected to the metal layer at the bottom of the first PI dielectric layer through a tenth signal metallized through hole;

[0014] The right end of the sixth microstrip line is connected to the sixth resonant metal line through the eleventh signal metallized through hole, the sixth resonant metal line is located on the upper surface of the first PI dielectric layer enclosed by the first rectangular ring metal layer, and the left end of the sixth microstrip line is connected to the metal layer of the bottom layer of the first PI dielectric layer through the twelfth signal metallized through hole.

[0015] The beneficial effects of adopting the above technical solution are: the filter includes a multi-layer dielectric structure and a metal structure, the multi-layer dielectric structure includes a single-layer DPC ceramic dielectric layer and four-layer PI thin film dielectric layers, the filter resonator is miniaturized by adopting the 1 / 4 wavelength stepped impedance resonator principle, cross-coupling is introduced, the 1 / 4 wavelength short-circuit microstrip line filter is improved, the microstrip line resonator is improved into a stripline resonator, the grounding distance is increased, the plane size of the resonator can be indirectly reduced, and it can be further miniaturized. Compared with the filter chip, the tap feeding replaces the gold wire bonding, which reduces the process difficulty and processing cost, and improves the signal transmission efficiency. The filter design has a short production cycle, the module can be directly connected to other substrates for use, and it is highly flexible. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0017] Figure 1 is a schematic diagram of the structure of the filter according to an embodiment of the present invention;

[0018] Figure 2 is a schematic diagram of the structure of the filter according to an embodiment of the present invention after the DPC ceramic dielectric layer is removed;

[0019] Figure 3 is a schematic diagram of the structure of the filter according to an embodiment of the present invention after the DPC ceramic dielectric layer is removed;

[0020] Figure 4-5 is a schematic structural diagram of the filter according to an embodiment of the present invention without the DPC ceramic dielectric layer and the second to fourth PI dielectric layers;

[0021] Figure 6 is a schematic diagram of a top view structure of the filter according to an embodiment of the present invention without the DPC ceramic dielectric layer and the second to fourth PI dielectric layers;

[0022] Figure 7This is the schematic diagram of a 1 / 4 wavelength stepped impedance resonator;

[0023] Figure 8 is a schematic diagram of filter simulation results in an embodiment of the present invention;

[0024] Wherein: 1. first PI dielectric layer; 2. DPC ceramic dielectric layer; 3. second PI dielectric layer; 4. third PI dielectric layer; 5. fourth PI dielectric layer; 6. first rectangular ring metal layer; 7. second rectangular ring metal layer; 8. grounding metallized hole; 9. first microstrip line; 10. sixth microstrip line; 11. first tap; 12. second tap; 13. first signal metallized through hole; 14. first resonant metal line; 15. second signal metallized through hole; 16. second microstrip line; 17. third signal metallized through hole; 18. second resonant metal line; 19. fourth signal Metallized through hole; 20, third microstrip line; 21, fifth signal metallized through hole; 22, third resonant metal line; 23, sixth signal metallized through hole; 24, fourth microstrip line; 25, seventh signal metallized through hole; 26, fourth resonant metal line; 27, eighth signal metallized through hole; 28, fifth microstrip line; 29, ninth signal metallized through hole; 30, fifth resonant metal line; 31, tenth signal metallized through hole; 32, eleventh signal metallized through hole; 33, sixth resonant metal line; 34, twelfth signal metallized through hole; 35, metallized hole interlayer pad. DETAILED DESCRIPTION

[0025] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0027] like Figure 1-Figure 6 As shown, an embodiment of the present invention discloses an embedded ceramic microfilter based on a multilayer thin film, including two taps and a resonator, wherein the resonator includes a multilayer dielectric structure and a metal structure, and the two taps are respectively connected to corresponding microstrip lines on the resonator, so that the taps and the resonator are combined together to form the filter.

[0028] Further, such as Figure 1-Figure 3As shown, the multilayer dielectric structure includes a first PI dielectric layer 1 located at the bottom layer, a DPC ceramic dielectric layer 2 is formed on the upper side of the first PI dielectric layer 1, and a second PI dielectric layer 3, a third PI dielectric layer 4 and a fourth PI dielectric layer 5 are sequentially formed on the upper surface of the DPC ceramic dielectric layer 2 from bottom to top. The lower surface of the first PI dielectric layer 1 is covered by a metal layer, a first rectangular ring metal layer 6 is formed between the first PI dielectric layer 1 and the DPC ceramic dielectric layer 2, a second rectangular ring metal layer 7 is formed between the second PI dielectric layer 3 and the DPC ceramic dielectric layer 2, the first rectangular ring metal layer 6 and the second rectangular ring metal layer 7 are overlapped in the vertical direction, a rectangular metal layer is formed on the left and right sides between the second PI dielectric layer 3 and the third PI dielectric layer 4, a rectangular metal layer is formed on the left and right sides between the third PI dielectric layer 4 and the fourth PI dielectric layer 5, and a rectangular metal layer is formed on the left and right sides of the upper surface of the fourth PI dielectric layer 5, and the rectangular metal layer overlaps the left and right parts of the second rectangular ring metal layer 7 in the vertical direction. The portion enclosed by the first rectangular ring metal layer 6 in the vertical direction constitutes the installation space of the metal structure in the resonator.

[0029] Further, such as Figure 4-Figure 5 As shown, the multilayer dielectric structure also includes a plurality of grounding metallized holes 8, which are vertically arranged and penetrate the first rectangular ring metal layer 6, the second rectangular ring metal layer 7 and contact the metal layer at the bottom of the first PI dielectric layer 1 and the rectangular metal layers on the left and right sides of the upper surface of the fourth PI dielectric layer 5. By arranging the grounding metallized holes 8 around the device, the stability of the filter signal transmission can be effectively improved.

[0030] Further, such as Figure 1 , Figure 3-Figure 6 As shown, the metal structure includes the first microstrip line 9 to the sixth microstrip line 10 located on the upper surface of the fourth PI dielectric layer 5 in the installation space, the first microstrip line 9 to the sixth microstrip line 10 are arranged along the left and right directions of the filter and do not contact each other, one end of the first tap 11 is connected to the middle of the first microstrip line 9, and one end of the second tap 12 is connected to the middle of the sixth microstrip line 10. Further, the first tap 11 and the second tap 12 include a first rectangular portion and a second rectangular portion, connected to the first microstrip line 9 and the sixth microstrip line 10 through the second rectangular portion, and the width of the first rectangular portion is greater than the width of the second rectangular portion.

[0031] Further, such as Figure 3-Figure 6As shown, the left end of the first microstrip line 9 is connected to the first resonant metal line 14 through the first signal metallized through hole 13, the first resonant metal line 14 is located on the upper surface of the first PI dielectric layer 1 enclosed by the first rectangular ring metal layer 6 (seen in the vertical direction), and the right end of the first microstrip line 9 is connected to the metal layer of the bottom layer of the first PI dielectric layer 1 through the second signal metallized through hole 15;

[0032] The right end of the second microstrip line 16 is connected to the second resonant metal line 18 through the third signal metallized through hole 17, the second resonant metal line 18 is located on the upper surface of the first PI dielectric layer 1 enclosed by the first rectangular ring metal layer 6 (seen in the vertical direction), and the left end of the second microstrip line 16 is connected to the metal layer of the bottom layer of the first PI dielectric layer 1 through the fourth signal metallized through hole 19;

[0033] The right end of the third microstrip line 20 is connected to the third resonant metal line 22 through the fifth signal metallized through hole 21, the third resonant metal line 22 is located on the upper surface of the first PI dielectric layer 1 enclosed by the first rectangular ring metal layer 6 (viewed from the vertical direction), and the left end of the third microstrip line 20 is connected to the metal layer of the bottom layer of the first PI dielectric layer 1 through the sixth signal metallized through hole 23;

[0034] The left end of the fourth microstrip line 24 is connected to the fourth resonant metal line 26 through the seventh signal metallized through hole 25, the fourth resonant metal line 26 is located on the upper surface of the first PI dielectric layer 1 enclosed by the first rectangular ring metal layer 6 (viewed from the vertical direction), and the right end of the fourth microstrip line 24 is connected to the metal layer of the bottom layer of the first PI dielectric layer 1 through the eighth signal metallized through hole 27;

[0035] The left end of the fifth microstrip line 28 is connected to the fifth resonant metal line 30 through the ninth signal metallized through hole 29, the fifth resonant metal line 30 is located on the upper surface of the first PI dielectric layer 1 enclosed by the first rectangular ring metal layer 6 (seen in the vertical direction), and the right end of the fifth microstrip line 28 is connected to the metal layer of the bottom layer of the first PI dielectric layer 1 through the tenth signal metallized through hole 31;

[0036] The right end of the sixth microstrip line 10 is connected to the sixth resonant metal line 33 through the eleventh signal metallized through hole 32, and the sixth resonant metal line 33 is located on the upper surface of the first PI dielectric layer 1 enclosed by the first rectangular ring metal layer 6 (viewed from the vertical direction). The left end of the sixth microstrip line 10 is connected to the metal layer of the bottom layer of the first PI dielectric layer 1 through the twelfth signal metallized through hole 34.

[0037] The first resonant metal line 14 is disposed opposite to the fourth resonant metal line 26 , and the fourth resonant metal line 26 is disposed opposite to the fifth resonant metal line 30 ; the second resonant metal line 18 is disposed opposite to the third resonant metal line 22 , and the third resonant metal line 22 is disposed opposite to the sixth resonant metal line 33 .

[0038] Further, such as Figure 3-Figure 5 As shown, the portions of the upper ends of the first signal metallized through hole 13 to the twelfth signal metallized through hole 34 that contact the second PI dielectric layer 3 , the third PI dielectric layer 4 and the fourth PI dielectric layer 5 are formed with metallized hole interlayer pads 35 .

[0039] Working principle: The signal is fed by the first tap 11 and then transmitted to the first microstrip line 9. The first microstrip line 9 transmits the signal to the first resonant metal line 14 through the first signal metallized through-hole 13. The first resonant metal line 14 couples the signal to another resonant metal line by coupling. The signals are coupled and propagated in sequence to achieve cross-coupling. A transmission zero point is introduced on one side of the high-frequency stop band to improve the high-frequency stop band response. After the resonator is cross-coupled, the signal is finally transmitted out by the second tap 12.

[0040] Compared with the filter chip, the filter described in this application has better performance and has made great progress in miniaturization and smaller size when the frequency band is similar. The specific comparison is shown in Table 1:

[0041] Table 1 - Device comparison table

[0042]

[0043]

[0044] The present application adopts the 1 / 4 wavelength stepped impedance resonator principle to design a miniaturized filter resonator, introduces cross coupling, introduces a transmission zero on one side of the high-frequency stopband, improves the high-frequency stopband response, and improves the 1 / 4 wavelength short-circuit microstrip line filter to improve the microstrip line resonator into a stripline resonator. The advantage is that the grounding distance becomes larger, which can indirectly reduce the planar size of the resonator and further miniaturize it.

[0045] The schematic diagram of 1 / 4 wavelength stepped impedance resonator is as follows Figure 7 As shown, it is composed of two sections with different impedance characteristics Z 1 , Z 2 The transmission line consists of 1 , L 2 Represent the electrical lengths of the two segments respectively. Ignoring the discontinuity of the transmission line, the input admittance of the open end is expressed as:

[0046]

[0047] Where Y 1 =1 / Z 1 , Y 2 =1 / Z 2 , according to the resonant condition of the resonator, let Y i =0, we get:

[0048] tanL 1 ·tan L 2 =R z (2)

[0049] In the formula, R Z =Y 1 / Y 2 =Z 2 / Z 1 The total length of the resonator can be expressed as:

[0050] L t =L 1 +L 2 (3)

[0051] The specific expression for the external quality factor is:

[0052]

[0053] The specific expression for the coupling coefficient is:

[0054]

[0055] Design a sixth-order 1 / 4 wavelength short-circuit Chebyshev bandpass filter with a center frequency of 11.3 GHz and a relative bandwidth (FBW) of 21%. The size of the resonator is preliminarily calculated according to formulas (1), (2), and (3). The g value of the low-pass prototype can be obtained by looking up Table 1. Substituting it into formulas (4) and (5), the Q is calculated. e1 =Q e6 =4.82, M 1,2 =M 5,6 =0.174, M 2,3 =M 4,5 =0.126, M 3,4 =0.174, the tap position and the spacing between the resonators can be obtained.

[0056] Table 2 In-band ripple 0.04321dB

[0057]

[0058] In the present application, under the condition of a certain electrical length of 1 / 4 wavelength, the distance of the grounding hole is extended in the three-dimensional direction to reduce the size of the resonator, so that the size of the resonator plane becomes smaller and miniaturization is achieved. The length of the designed filter can be 2mm, the width can be 1.85mm, and the height can be 0.3mm.

[0059] Figure 8 This is the simulation result of the filter for this application. It can be seen that the return loss in the passband is better than that of the same type of filter chip, and the center insertion loss is smaller than that of the same type of filter chip, but it is slightly inferior in out-of-band suppression.

[0060] The filter described in this application proposes to extend the distance of the grounding hole by three-dimensionally extending the 1 / 4 short-circuit wavelength transmission line, reduce the plane size of the resonator, and further miniaturize it. Compared with the filter chip with the same performance, it is smaller in size. Compared with the bare core, it does not require gold wire bonding, cavity digging, and buried cavity placement. It is simpler to use in terms of process and has lower cost. By adopting the tap feeding method, the signal transmission efficiency is better than the gold wire bonding of the chip, and it can be directly connected to other substrates for use. It has high flexibility and a short production and design period for this kind of filter.

Claims

1. An embedded ceramic microfilter based on a multilayer thin film, characterized in that: It comprises two taps and a resonator, wherein the resonator comprises a multi-layer dielectric structure and a metal structure, and the two taps are respectively connected to corresponding microstrip lines on the resonator, so that the taps and the resonator are combined together to form the filter.

2. The embedded ceramic microfilter based on multilayer thin film according to claim 1, characterized in that: The multilayer dielectric structure comprises a first PI dielectric layer (1) located at the bottom layer, a DPC ceramic dielectric layer (2) is formed on the upper side of the first PI dielectric layer (1), a second PI dielectric layer (3), a third PI dielectric layer (4) and a fourth PI dielectric layer (5) are sequentially formed on the upper surface of the DPC ceramic dielectric layer (2) from bottom to top, the lower surface of the first PI dielectric layer (1) is covered by a metal layer, a first rectangular ring metal layer (6) is formed between the first PI dielectric layer (1) and the DPC ceramic dielectric layer (2), and the second PI dielectric layer (3) and the DPC ceramic dielectric layer (2) are connected to each other. A second rectangular ring metal layer (7) is formed between the first rectangular ring metal layer (6) and the second rectangular ring metal layer (7) are arranged overlapping in the vertical direction; a rectangular metal layer is formed on the left and right sides between the second PI dielectric layer (3) and the third PI dielectric layer (4); a rectangular metal layer is formed on the left and right sides between the third PI dielectric layer (4) and the fourth PI dielectric layer (5); a rectangular metal layer is formed on the left and right sides of the upper surface of the fourth PI dielectric layer (5); and the rectangular metal layers are overlapped with the left and right parts of the second rectangular ring metal layer (7) in the vertical direction.

3. The embedded ceramic microfilter based on multilayer thin film according to claim 2, characterized in that: The portion enclosed by the first rectangular ring metal layer (6) in the vertical direction constitutes an installation space for the metal structure in the resonator.

4. The embedded ceramic microfilter based on multilayer thin film according to claim 1, characterized in that: The multilayer dielectric structure further comprises a plurality of grounding metallized holes (8), wherein the grounding metallized holes (8) are arranged vertically and penetrate the first rectangular ring metal layer (6), the second rectangular ring metal layer (7) and are in contact with the metal layer at the bottom layer of the first PI dielectric layer (1) and the rectangular metal layers on the left and right sides of the upper surface of the fourth PI dielectric layer (5).

5. The embedded ceramic microfilter based on multilayer thin film according to claim 3, characterized in that: The metal structure comprises a first microstrip line (9) to a sixth microstrip line (10) located on the upper surface of a fourth PI dielectric layer (5) in the installation space, the first microstrip line (9) to the sixth microstrip line (10) extending left and right and not contacting each other, one end of a first tap (11) connected to the middle of the first microstrip line (9), and one end of a second tap (12) connected to the middle of the sixth microstrip line (10).

6. The embedded ceramic microfilter based on multilayer thin film according to claim 5, characterized in that: The first tap (11) and the second tap (12) comprise a first rectangular portion and a second rectangular portion, and are connected to the first microstrip line (9) and the sixth microstrip line (10) via the second rectangular portion, wherein the width of the first rectangular portion is greater than the width of the second rectangular portion.

7. The embedded ceramic microfilter based on multi-layer thin film according to claim 5, characterized in that: The left end of the first microstrip line (9) is connected to the first resonant metal line (14) through a first signal metallized through hole (13); the first resonant metal line (14) is located on the upper surface of the first PI dielectric layer (1) enclosed by the first rectangular ring metal layer (6); and the right end of the first microstrip line (9) is connected to the metal layer at the bottom layer of the first PI dielectric layer (1) through a second signal metallized through hole (15); The right end of the second microstrip line (16) is connected to the second resonant metal line (18) via a third signal metallized through hole (17); the second resonant metal line (18) is located on the upper surface of the first PI dielectric layer (1) enclosed by the first rectangular ring metal layer (6); and the left end of the second microstrip line (16) is connected to the metal layer at the bottom layer of the first PI dielectric layer (1) via a fourth signal metallized through hole (19); The right end of the third microstrip line (20) is connected to the third resonant metal line (22) via a fifth signal metallized through hole (21); the third resonant metal line (22) is located on the upper surface of the first PI dielectric layer (1) enclosed by the first rectangular ring metal layer (6); and the left end of the third microstrip line (20) is connected to the metal layer at the bottom layer of the first PI dielectric layer (1) via a sixth signal metallized through hole (23); The left end of the fourth microstrip line (24) is connected to the fourth resonant metal line (26) via a seventh signal metallized through hole (25); the fourth resonant metal line (26) is located on the upper surface of the first PI dielectric layer (1) enclosed by the first rectangular ring metal layer (6); and the right end of the fourth microstrip line (24) is connected to the metal layer at the bottom layer of the first PI dielectric layer (1) via an eighth signal metallized through hole (27); The left end of the fifth microstrip line (28) is connected to the fifth resonant metal line (30) via a ninth signal metallized through hole (29); the fifth resonant metal line (30) is located on the upper surface of the first PI dielectric layer (1) enclosed by the first rectangular ring metal layer (6); and the right end of the fifth microstrip line (28) is connected to the metal layer at the bottom layer of the first PI dielectric layer (1) via a tenth signal metallized through hole (31); The right end of the sixth microstrip line (10) is connected to the sixth resonant metal line (33) via an eleventh signal metallized through hole (32); the sixth resonant metal line (33) is located on the upper surface of the first PI dielectric layer (1) enclosed by the first rectangular ring metal layer (6); and the left end of the sixth microstrip line (10) is connected to the metal layer at the bottom layer of the first PI dielectric layer (1) via a twelfth signal metallized through hole (34).

8. The embedded ceramic microfilter based on multi-layer thin film according to claim 7, characterized in that: The upper ends of the first signal metallized through hole (13) to the twelfth signal metallized through hole (34) in contact with the second PI dielectric layer (3), the third PI dielectric layer (4) and the fourth PI dielectric layer (5) are formed with metallized hole interlayer pads (35).

9. The embedded ceramic microfilter based on multi-layer thin film according to claim 7, characterized in that: The first resonant metal line (14) is arranged opposite to the fourth resonant metal line (26), and the fourth resonant metal line (26) is arranged opposite to the fifth resonant metal line (30); the second resonant metal line (18) is arranged opposite to the third resonant metal line (22), and the third resonant metal line (22) is arranged opposite to the sixth resonant metal line (33).

10. The embedded ceramic microfilter based on multi-layer thin film according to claim 1, characterized in that: The filter has a length of 2 mm, a width of 1.85 mm, and a height of 0.295 mm.

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