LTCC band-pass filter and preparation method thereof
By optimizing the inductance arrangement in the LTCC bandpass filter, symmetrical arrangement left and right, and adjusting the coupling coefficient, the problems of small proximal suppression and narrow suppression band of the existing filter are solved, and optimized proximal suppression and selectivity are achieved.
Patent Information
- Application Number
- CN202411991995.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-31
- Publication Date
- 2025-04-11
AI Technical Summary
The existing LTCC bandpass filters have small proximal suppression and narrow suppression bands, making it difficult to meet certain application needs.
By arranging two of the four inductors in the LTCC bandpass filter and symmetrically arranged left and right, the inductors at the input and output ends are located above, with a large space and flexible adjustment of the spacing, thereby adjusting the coupling coefficient, and obtaining two other zero points, optimizing the near-end rejection and selectivity of the filter.
By adjusting the coupling coefficient, the near-end rejection and selectivity of the filter are optimized, and the performance of the filter is improved.
Smart Images
Figure CN119812706A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a LTCC bandpass filter and a preparation method thereof, belonging to the technical field of LTCC bandpass filters. Background Art
[0002] A bandpass filter is an electronic filter that allows signals in a specific frequency band to pass through while suppressing signals in other frequency bands. The amplitude-frequency characteristics of bandpass filters make them widely used in audio processing, communication systems, radio modulation and demodulation, image processing and other fields.
[0003] LTCC bandpass filter, due to the arrangement structure of the four inductors, the original circuit has a zero point on the left and right, the proximal suppression is small and the suppression band is narrow. Summary of the invention
[0004] The technical problem to be solved by the present invention is to provide an LTCC bandpass filter and a preparation method thereof, with small proximal suppression and a narrow suppression band.
[0005] The technical solution adopted by the present invention is: an LTCC bandpass filter, including an LTCC ceramic body, a first inductor, a second inductor, a first capacitor, a second capacitor, a third capacitor, a fourth capacitor and a fifth capacitor, the first inductor and the second inductor are arranged on the upper and lower sides of the left side of the LTCC ceramic body respectively, the first capacitor and the second capacitor are arranged in the middle of the left side of the LTCC ceramic body near the left end, the third capacitor and the fourth capacitor are arranged at the bottom of the LTCC ceramic body, the fifth capacitor is a double capacitor, axially symmetrically arranged in the middle of the LTCC ceramic body, a mirror structure symmetrical to the first inductor, the second inductor, the first capacitor, the second capacitor, the third capacitor and the fourth capacitor is arranged on the right side of the LTCC ceramic body, the first capacitor and the first inductor are connected to the input pin set at the left end of the LTCC ceramic body, the capacitor and inductor mirrored with the first capacitor and the first inductor are connected to the output pin set at the right end of the LTCC ceramic body, and the third capacitor and the fourth capacitor are connected to the test ground terminals set at the front and rear sides of the LTCC ceramic body.
[0006] Furthermore, the first capacitor, the second capacitor and the fifth capacitor share a middle electrode plate, the other electrode plates of the first capacitor and the second capacitor are respectively located at the upper and lower sides of the left end of the middle electrode plate, and the other electrode plate of the fifth capacitor is located at the upper right end of the middle electrode plate.
[0007] A method for preparing a LTCC bandpass filter, the method comprising the following steps: S1. Ingredients: Select a material with a dielectric constant of 40, and ball-mill the powder into a particle size of 0.5-1 μm; S2, tape casting: the ingredients after ball milling are prepared into slurry, and the green porcelain tapes with thicknesses of 43μm, 50μm, 38μm, etc. are obtained by tape casting technology; S3, cutting: cutting the raw porcelain tape into raw porcelain tapes of various thicknesses of 6 inches; S4, drilling: according to the prepared drilling pattern, use a laser drilling machine to drill holes on the raw porcelain belt that needs to be drilled; S5. Printing: The printing method is screen printing. The design pattern is prepared on the film. After exposure, the inductor is transferred to the 400 and 500 mesh steel screens covered by the photosensitive adhesive to form a printing jig. The large area G layer uses 500 mesh; by controlling the thickness of the photosensitive adhesive coating: 37μm~43μm; printing GAP value: 1mm~2mm; printing scraper pressure: 0.05MPa~0.10MPa; scraper step speed 0.05m / s~0.10m / s; each layer of the design model is printed on the raw porcelain tape of corresponding thickness. The printed inductor line width error is within 2μm, the inductor thickness is 12-15μm, the printed capacitor length and width error is within 5μm, and the capacitor thickness is 8-10μm; S6, lamination: lamination of each printed raw ceramic tape according to the design sequence using a fully automatic alignment lamination machine; S7, Isostatic Pressing: The laminated membrane is subjected to final pressing by isostatic pressing; the maximum isostatic pressing temperature is 70℃±5℃; the holding time is 800s~900s; the holding pressure is 5100psi~8300psi, forming a Bar block; S8, cutting: divide the Bar block into independent product units with an error of ±0.1mm and a size of 3.87mm*1.93mm; S9, debinding: Debinding the split products for 36 hours according to the debinding curve of the material with a dielectric constant of 40; S10, sintering: the debinding products are sintered in a tunnel furnace; the tunnel furnace has a belt speed of 45mm / min, 12 sintering temperature zones, a sintering temperature of 900℃, and a holding time of 50min~60min; S11. Chamfering: Chamfer the sintered product, use a roller for 6 hours, use 2600ml of grinding media, and add 2250-2350ml of water; S12, Silver Dipping: Use a fully automatic terminal electrode silver dipping machine to coat the external terminal electrodes of the chamfered products; S13, Silver Burning: Silver burning process is performed on the silver-coated products; silver burning is performed using a tunnel furnace; there are 6 sintering temperature zones, sintering temperature: 715°C, and holding time: 20min~25min; S14, electroplating: The silver-sintered product is electroplated with nickel, tin and lead to obtain the final product. Beneficial effects of the present invention: The present invention arranges two of the four inductors at the top and bottom, and arranges them symmetrically. The inductors at the input end and the output end are located at the top, with a large space, and the spacing can be flexibly adjusted, thereby adjusting the coupling coefficient. By adjusting the coupling coefficient of the two inductors, two other zero points are obtained, the near-end suppression of the filter is optimized, and the selectivity of the filter is improved. BRIEF DESCRIPTION OF THE DRAWINGS
[0009] Figure 1 It is a schematic diagram of the three-dimensional structure of the LTCC bandpass filter; Figure 2 It is a schematic diagram of the three-dimensional structure of the internal electrical components of the LTCC bandpass filter; Figure 3 This is a three-dimensional structural diagram of the internal electrical components of the LTCC bandpass filter from another perspective; Figure 4 It is a front view structural diagram of the arrangement of the internal electrical components of the LTCC bandpass filter; Figure 5 This is a schematic diagram of the rear view of the internal electrical components of the LTCC bandpass filter; Figure 6 This is a right-view structural diagram of the arrangement of the internal electrical components of the LTCC bandpass filter; Figure 7 It is a top view structural diagram of the arrangement of the internal electrical components of the LTCC bandpass filter; Figure 8 This is a schematic diagram of the LTCC bandpass filter circuit principle; Fig. 9 This is the ADS simulation waveform of the LTCC bandpass filter; Fig.10 This is a transparent front view of the LTCC bandpass filter (bringing the input and output inductors (in the black box) closer together will create a second zero point, thereby improving product selectivity); Fig.11 This is the simulation waveform of the LTCC bandpass filter three-dimensional model (the waveform and the ideal circuit simulation waveform have two zero points added); Fig.12 It is the S parameter curve of LTCC bandpass filter model simulation. DETAILED DESCRIPTION
[0010] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.
[0011] Example 1: Figure 1-11, an LTCC bandpass filter, comprising an LTCC ceramic body 1, a first inductor 2, a second inductor 3, a first capacitor 4, a second capacitor 5, a third capacitor 6, a fourth capacitor 7 and a fifth capacitor 8, wherein the first inductor 2 and the second inductor 3 are arranged on the upper and lower sides of the left side of the LTCC ceramic body 1, respectively, the first capacitor 4 and the second capacitor 5 are arranged in the middle of the left side of the LTCC ceramic body 1 near the left end, the third capacitor 6 and the fourth capacitor 7 are arranged at the bottom of the LTCC ceramic body 1, the fifth capacitor 8 is a double capacitor, which is axially symmetrically arranged in the middle of the LTCC ceramic body 1, and the first inductor 2, the second inductor 3, the first capacitor 4, the second capacitor 5, the third capacitor 6 and the fourth capacitor 7 are arranged on the right side of the LTCC ceramic body 1. The first capacitor 4 and the first inductor 2 are connected to the input pin 9 set at the left end of the LTCC ceramic body 1, and the capacitor and inductor mirrored with the first capacitor 4 and the first inductor 2 are connected to the output pin 10 set at the right end of the LTCC ceramic body 1. The third capacitor 6 and the fourth capacitor 7 are connected to the test ground terminal 11 set at the front and rear sides of the LTCC ceramic body 1. The present invention arranges two inductors at the top and bottom, and arranges them symmetrically. The inductors at the input and output ends are located at the top, with large space, and the spacing can be flexibly adjusted, so as to adjust the coupling coefficient. By adjusting the coupling coefficient of the two inductors, two other zero points are obtained, and the near-end suppression of the filter is optimized, thereby improving the selectivity of the filter. .
[0012] The above-mentioned first capacitor 4, second capacitor 5 and fifth capacitor 8 share a middle electrode plate, the other electrode plates of the first capacitor 4 and the second capacitor 5 are respectively located at the upper and lower sides of the left end of the middle electrode plate, the other electrode plate of the fifth capacitor 8 is located at the upper right end of the middle electrode plate, the other electrode plate of the first capacitor 4 is connected to one end of the first inductor 2 through a first short terminal 12, the other end of the first inductor 2 is electrically connected to the other electrode plate of the second capacitor 5 through a first long terminal 13 arranged in the middle, the lower end of the second inductor 3 is connected to the upper electrode plate of the fourth capacitor 7 through a second short terminal 15, the front side of the upper end of the second inductor 3 is electrically connected to the common electrode plate of the first capacitor 4, the second capacitor 5 and the fifth capacitor 8 and the two electrode plates of the third capacitor 6 through a second long terminal 14, and the electrode plate of the fifth capacitor 8 is connected to the middle electrode plates of the first capacitor 4, the second capacitor 5 and the fifth capacitor 8 through a third short terminal 16.
[0013] The circuit of the LTCC bandpass filter includes two cascaded bandpass filter circuits, the two cascaded bandpass filters are connected in series through a capacitor C7 (fifth capacitor 8), and the front-stage bandpass filter circuit includes an inductor L1 (first inductor 1), one end of the inductor L1 is electrically connected to an input pin 9 and a section of a capacitor C3 (second capacitor 5), and the other end is electrically connected to one end of a first capacitor C1 (first capacitor 4), and the other end of the first capacitor C1 is electrically connected to the other end of the capacitor C3, the capacitor C5 (fourth capacitor 7), the capacitor C7 (fifth capacitor 7) and the inductor L 3 (second inductor 2), the other end of inductor L3 is electrically connected to one end of capacitor C6 (third capacitor 6), the other ends of capacitor C6 and capacitor C5 are electrically connected to the test ground terminal 11, the post-stage band-pass filter circuit includes inductor L2, inductor L4, capacitor C2, capacitor C4, capacitor C8 and capacitor C9 which are symmetrically electrically connected to the inductor and capacitor of the pre-stage band-pass filter, capacitor C2 is connected to the test ground terminal 11, inductor L2 and capacitor C4 are connected to output pin 10, capacitor C2 is connected to capacitor C7, and the remaining connection relationships refer to the pre-stage band-pass filter circuit.
[0014] Embodiment 2: A method for preparing a LTCC bandpass filter, the method comprising the following steps: S1. Ingredients: Select a material with a dielectric constant of 40, and ball-mill the powder into a particle size of 0.5-1 μm; S2, tape casting: the ingredients after ball milling are prepared into slurry, and the green porcelain tapes with thicknesses of 43μm, 50μm, 38μm, etc. are obtained by tape casting technology; S3, cutting: cutting the raw porcelain tape into raw porcelain tapes of various thicknesses of 6 inches; S4, drilling: according to the prepared drilling pattern, use a laser drilling machine to drill holes on the raw porcelain belt that needs to be drilled; S5. Printing: The printing method is screen printing. The design pattern is prepared on the film. After exposure, the inductor is transferred to the 400 and 500 mesh steel screens covered by the photosensitive adhesive to form a printing jig. The large area G layer uses 500 mesh; by controlling the thickness of the photosensitive adhesive coating: 37μm~43μm; printing GAP value: 1mm~2mm; printing scraper pressure: 0.05MPa~0.10MPa; scraper step speed 0.05m / s~0.10m / s; each layer of the design model is printed on the raw porcelain tape of corresponding thickness. The printed inductor line width error is within 2μm, the inductor thickness is 12-15μm, the printed capacitor length and width error is within 5μm, and the capacitor thickness is 8-10μm; S6, lamination: lamination of each printed raw ceramic tape according to the design sequence using a fully automatic alignment lamination machine; S7, Isostatic Pressing: The laminated membrane is subjected to final pressing by isostatic pressing; the maximum isostatic pressing temperature is 70℃±5℃; the holding time is 800s~900s; the holding pressure is 5100psi~8300psi, forming a Bar block; S8, cutting: divide the Bar block into independent product units with an error of ±0.1mm and a size of 3.87mm*1.93mm; S9, debinding: Debinding the split products for 36 hours according to the debinding curve of the material with a dielectric constant of 40; S10, sintering: the debinding products are sintered in a tunnel furnace; the tunnel furnace belt speed is 45mm / min, there are 12 sintering temperature zones, the sintering temperature is 900℃, and the holding time is 50min~60min; S11. Chamfering: Chamfer the sintered product, use a roller for 6 hours, use 2600ml of grinding media, and add 2250-2350ml of water; S12, Silver Dipping: Use a fully automatic terminal electrode silver dipping machine to coat the external terminal electrodes of the chamfered products; S13, Silver Burning: Silver burning process is performed on the silver-coated products; silver burning is performed using a tunnel furnace; there are 6 sintering temperature zones, sintering temperature: 715°C, and holding time: 20min~25min; S14, electroplating: The silver-sintered product is electroplated with nickel, tin and lead to obtain the final product. The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.
Claims
1. A LTCC bandpass filter, characterized in that: The invention comprises an LTCC ceramic body (1), a first inductor (2), a second inductor (3), a first capacitor (4), a second capacitor (5), a third capacitor (6), a fourth capacitor (7) and a fifth capacitor (8). The first inductor (2) and the second inductor (3) are arranged on the upper and lower sides of the left side of the LTCC ceramic body (1), respectively. The first capacitor (4) and the second capacitor (5) are arranged in the middle of the left side of the LTCC ceramic body (1) near the left end. The third capacitor (6) and the fourth capacitor (7) are arranged at the bottom of the LTCC ceramic body (1). The fifth capacitor (8) is a dual capacitor and is axially symmetrically arranged in the middle of the LTCC ceramic body (1). A mirror structure symmetrical to the first inductor (2), the second inductor (3), the first capacitor (4), the second capacitor (5), the third capacitor (6) and the fourth capacitor (7) is arranged inside the right side of the LTCC ceramic body (1); the first capacitor (4) and the first inductor (2) are connected to an input pin (9) arranged at the left end of the LTCC ceramic body (1); the capacitor and inductor mirroring the first capacitor (4) and the first inductor (2) are connected to an output pin (10) arranged at the right end of the LTCC ceramic body (1); and the third capacitor (6) and the fourth capacitor (7) are connected to a test ground terminal (11) arranged at the front and rear sides of the LTCC ceramic body (1).
2. The LTCC bandpass filter according to claim 1, characterized in that: The first capacitor (4), the second capacitor (5) and the fifth capacitor (8) share a middle electrode plate, the other electrode plates of the first capacitor (4) and the second capacitor (5) are respectively located at the upper and lower sides of the left end of the middle electrode plate, and the other electrode plate of the fifth capacitor (8) is located at the upper part of the right end of the middle electrode plate.
3. The method for preparing a LTCC bandpass filter according to claim 1, characterized in that: The method comprises the following steps: S1. Ingredients: Select a material with a dielectric constant of 40, and ball-mill the powder into a particle size of 0.5-1 μm; S2, tape casting: the ingredients after ball milling are prepared into slurry, and the green porcelain tapes with thicknesses of 43μm, 50μm, 38μm, etc. are obtained by tape casting technology; S3, cutting: cutting the raw porcelain tape into raw porcelain tapes of various thicknesses of 6 inches; S4, drilling: according to the prepared drilling pattern, use a laser drilling machine to drill holes on the raw porcelain belt that needs to be drilled; S5. Printing: The printing method is screen printing. The design pattern is prepared on the film. After exposure, the inductor is transferred to the 400 and 500 mesh steel screens covered by the photosensitive adhesive to form a printing jig. The large area G layer uses 500 mesh; by controlling the thickness of the photosensitive adhesive coating: 37μm~43μm; printing GAP value: 1mm~2mm; printing scraper pressure: 0.05MPa~0.10MPa; scraper step speed 0.05m / s~0.10m / s; each layer of the design model is printed on the raw porcelain tape of corresponding thickness. The printed inductor line width error is within 2μm, the inductor thickness is 12-15μm, the printed capacitor length and width error is within 5μm, and the capacitor thickness is 8-10μm; S6, lamination: lamination of each printed raw ceramic tape according to the design sequence using a fully automatic alignment lamination machine; S7, Isostatic Pressing: The laminated membrane is subjected to final pressing by isostatic pressing; the maximum isostatic pressing temperature is 70℃±5℃; the holding time is 800s~900s; the holding pressure is 5100psi~8300psi, forming a Bar block; S8, cutting: divide the Bar block into independent product units with an error of ±0.1mm and a size of 3.87mm*1.93mm; S9, debinding: Debinding the split products for 36 hours according to the debinding curve of the material with a dielectric constant of 40; S10, sintering: the debinding products are sintered in a tunnel furnace; the tunnel furnace belt speed is 45mm / min, there are 12 sintering temperature zones, the sintering temperature is 900℃, and the holding time is 50min~60min; S11. Chamfering: Chamfer the sintered product, use a roller for 6 hours, use 2600ml of grinding media, and add 2250-2350ml of water; S12, Silver Dipping: Use a fully automatic terminal electrode silver dipping machine to coat the external terminal electrodes of the chamfered products; S13, Silver Burning: Silver burning process is performed on the silver-coated products; silver burning is performed using a tunnel furnace; there are 6 sintering temperature zones, sintering temperature: 715°C, and holding time: 20min~25min; S14, electroplating: After silver firing, the product is electroplated with nickel, tin and lead to obtain the final product.