350-2000MHz high-pass filter and preparation method thereof

Abstract

The invention discloses a 350-2000MHz high-pass filter which comprises a 350-690MHz filter, a 690-1250MHz filter and a 1250-2000MHz filter which are connected in parallel, two sections are connected with a change-over switch after parallel connection, and each of the three filters comprises a porcelain body, a first inductor, a second inductor, a third inductor, a fourth inductor, a first capacitor, a second capacitor, a third capacitor, a fourth capacitor and a fifth capacitor. A first capacitor, a second capacitor, a third capacitor, a fourth capacitor and a fifth capacitor which are electrically connected in sequence are arranged in the porcelain body to form a series capacitor layer, a first inductor, a second inductor, a third inductor and a fourth inductor are arranged in the porcelain body to form an inductor layer, and the input end and the output end of the series capacitor layer are connected to an input pin and an output pin respectively. And the first inductor, the second inductor, the third inductor and the fourth inductor are connected to a sixth capacitor, a seventh capacitor, an eighth capacitor and a ninth capacitor which are externally connected with the bottom of the porcelain body through lower inner electrodes and are variable in capacitance. By adopting the variable capacitor, the frequency can be adjusted.

Description

Technical Field

[0001] The invention relates to a 350-2000MHz high-pass filter and a preparation method thereof, belonging to the technical field of high-pass filters. Background Art

[0002] A high-pass filter is a system that allows high frequencies to pass more easily and blocks low frequencies from passing through. It filters out unnecessary low-frequency components in the signal or filters out low-frequency interference.

[0003] The existing LTCC high-pass filter is a filter with a fixed cut-off frequency. All components are integrated inside the ceramic body and the frequency is not variable. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a 350-2000MHz high-pass filter and a preparation method thereof, which can meet the requirement of variable frequency.

[0005] The technical solution adopted by the present invention is: a 350-2000MHz high-pass filter, comprising a 350-690MHz filter, a 690-1250MHz filter and a 1250-2000MHz filter connected in parallel, wherein the two sections after the parallel connection are connected with a conversion switch, wherein the 350-690MHz filter, the 690-1250MHz filter and the 1250-2000MHz filter all comprise a LTCC porcelain body, a first inductor, a second inductor, a third inductor, a fourth inductor, a first capacitor, a second capacitor, a third capacitor, a fourth capacitor and a fifth capacitor, wherein the first capacitor, the second capacitor, the third capacitor, the fourth capacitor and the fifth capacitor are arranged in the porcelain body and are electrically connected in sequence. The four capacitors and the fifth capacitor form a series capacitor layer. The first inductor, the second inductor, the third inductor, and the fourth inductor are three-dimensional inductors, which are arranged in the porcelain body to form an inductor layer. The formed inductor layer is located below the series capacitor layer. The input and output ends of the series capacitor layer are respectively connected to the input pins and output pins arranged on the series capacitor layer and the bottom of the porcelain body through the upper inner electrode and the side inner electrode. The first inductor, the second inductor, the third inductor, and the fourth inductor are all connected to the five external capacitor connection ends at the bottom of the porcelain body through the lower inner electrode. The five external capacitor connection ends are respectively connected to the sixth capacitor, the seventh capacitor, the eighth capacitor, and the ninth capacitor. The sixth capacitor, the seventh capacitor, the eighth capacitor, and the ninth capacitor are variable capacitors. Furthermore, the distance between the capacitor layer and the inductor layer is 10-40 um.

[0006] A method for preparing a 350-2000 MHz high-pass filter, the method comprising the following steps: S1. Ingredients: Select a material with a dielectric constant of 5.1, and ball-mill the powder into a particle size of 0.3-0.5 μm; S2, tape casting: the ingredients after ball milling are prepared into slurry, and the raw porcelain tapes of different thicknesses 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 filter design pattern of the corresponding frequency band of the high-pass filter is prepared on the film. After exposure, the inductance of the filter and the capacitor installed inside the porcelain body are transferred to the 500-mesh steel screen covered by the photosensitive adhesive (higher precision printing lines). The capacitor uses a 400-mesh steel screen to form a printing jig; by controlling the thickness of the photosensitive adhesive coating: 42μm-55μm; printing GAP value: 1mm-3mm; printing scraper pressure: 0.05MPa-0.10MPa; scraper step speed 0.01m / s-0.05m / s; each layer of the design model containing the inductor or capacitor pattern is printed on the raw porcelain tape of the corresponding thickness, the printed inductor line width error is within 1μm, 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 85±5℃; the holding time is 900s; the holding pressure is 5100±100psi, forming a Bar block; S8, cutting: divide the Bar block into independent product units of 6.95mm*4.63mm with an error of ±0.02mm; S9, debinding: Debinding the split products for 36 hours according to the staged temperature debinding curve with a dielectric constant of 5.1. The staged temperatures of the debinding curve are as follows: gradually increase the temperature from RT to 270℃ for 15h; keep constant at 270℃ for 2h; gradually increase the temperature from 270 to 320℃ for 4h; keep constant at 320℃ for 2h; gradually increase the temperature from RT to 270℃ for 5h; gradually increase the temperature from 320 to 465℃ for 4h; keep constant at 465℃ for 5h; gradually cool down from 465℃ to RT; S10, sintering: the debinding product is sintered in a tunnel furnace; the tunnel furnace belt speed is 45mm / min, there are 12 sintering temperature zones, the sintering temperature is 875℃, and the sintering time is 1h: S11, chamfering: chamfering the sintered product; 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 carried out on the silver-coated products; silver burning is carried out using a tunnel furnace; there are 6 sintering temperature zones, sintering temperature: 715℃, and holding time: 20min-25min; S14, electroplating: After silver firing, the product is electroplated with nickel, tin and lead to obtain the final product.

[0007] The beneficial effects of the present invention are as follows: compared with the prior art, the present invention can realize the requirement of variable frequency high-pass filter by adjusting the variable capacitor through external variable capacitor, thereby realizing the requirement of variable frequency band of 350-2000MHz high-pass filter prepared by LTCC, and effectively solving the problem of fixed frequency of the existing LTCC high-pass filter; through simulation verification, the filters of the three frequency bands all realize the control of the three frequency bands through variable capacitance changes. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a schematic diagram of the 350-690MHz filter's three-dimensional perspective structure; Figure 2 It is a schematic diagram of the three-dimensional structure of the internal device arrangement of the 350-690MHz filter; Figure 3 This is a three-dimensional structural diagram of the internal device layout of the 350-690MHz filter from another perspective; Figure 4 This is a front view schematic diagram of the 350-690MHz filter internal device connection and external capacitor arrangement; Figure 5 This is the left-view structural diagram of the internal device arrangement of the 350-690MHz filter; Figure 6 This is a top view of the internal device layout of the 350-690MHz filter; Figure 7 This is the simulation circuit diagram of the 350-690MHz filter; Figure 8 This is the simulation waveform of the 350-690MHz filter. In the figure, (a) is 3PF and (b) is 30PF. Fig. 9 It is a 3D perspective structural diagram of the 690-1250MHz filter; Fig.10 This is the simulation waveform of the 690-1250MHz filter. In the figure, (a) is 2.5PF and (b) is 30PF; Fig.11 It is a three-dimensional perspective structural diagram of the 1250-2000MHz filter; Fig.12 This is the simulation waveform of the 1250-2000MHz filter. In the figure, (a) is 2PF and (b) is 30PF. DETAILED DESCRIPTION

[0009] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0010] Example 1: Figure 1-12 As shown, a 350-2000MHz high-pass filter comprises a 350-690MHz filter, a 690-1250MHz filter and a 1250-2000MHz filter connected in parallel, wherein the two sections connected in parallel are connected with a conversion switch, wherein the 350-690MHz filter, the 690-1250MHz filter and the 1250-2000MHz filter all comprise a LTCC ceramic body 1, a first inductor 2, a second inductor 3, a third inductor 4, a fourth inductor 5, a first capacitor 6, a second capacitor 7, a third capacitor 8, a fourth capacitor 9 and a fifth capacitor 10, wherein the ceramic body 1 is provided with a first capacitor 6, a second capacitor 7, a third capacitor 8, a fourth capacitor 9 and a fifth capacitor 10 which are electrically connected in sequence to form a series capacitor layer, The first inductor 2, the second inductor 3, the third inductor 4, and the fourth inductor 5 are three-dimensional inductors, which are arranged in the ceramic body 1 to form an inductor layer, and the formed inductor layer is located below the series capacitor layer. The input and output ends of the series capacitor layer are respectively connected to the input pin 11 and the output pin 12 arranged at the bottom of the series capacitor layer and the ceramic body 1 through the upper inner electrode 18 and the side inner electrode 19. The first inductor 2, the second inductor 3, the third inductor 4, and the fourth inductor 5 are all connected to the five external capacitor connection terminals 13 at the bottom of the ceramic body 1 through the lower inner electrode 20. The five external capacitor connection terminals 13 are respectively connected to the sixth capacitor 14, the seventh capacitor 15, the eighth capacitor 16, and the ninth capacitor 17. The sixth capacitor 14, the seventh capacitor 15, the eighth capacitor 16, and the ninth capacitor 17 are variable capacitors. In order to achieve adjustable cut-off frequency, the grounding capacitor is designed to be external, and a variable capacitor is used instead to achieve variable capacitance, thereby achieving variable frequency.

[0011] In order to meet the requirements and avoid mutual interference, the spacing between the capacitor layer and the inductor layer is 10-40um.

[0012] The first frequency of the present invention covers 350-690MHz, and the frequency is adjustable by external variable capacitor. The waveform when the capacitance value is 3PF has a cut-off frequency of 690MHz. Figure 8 (a) shows the waveform when the capacitance value is 30PF and the cut-off frequency is 350MHz. Figure 8 As shown in (b), the filter frequency coverage of 350-690MHz is achieved by changing the capacitance from 3 to 30PF.

[0013] The second frequency of the present invention covers 650-1250MHz, the waveform when the capacitance value is 2.5PF, and the cut-off frequency is 1250MHz, as shown in 10 (a). The waveform when the capacitance value is 30PF, and the cut-off frequency is 650MHz, as shown in Fig.10 As shown in (b), the filter frequency coverage of 650-1250MHz is achieved by changing the capacitance from 2.5 to 30PF.

[0014] The third frequency of the present invention covers 1220-2000MHz, the waveform when the capacitance value is 2PF, and the cut-off frequency is 2000MHz, such as Fig.12 (a) shows the waveform when the capacitance value is 30PF and the cut-off frequency is 1220MHz. Fig.12 As shown in (b), the filter frequency covers 1220-2000MHz by changing the capacitance from 2-30PF.

[0015] The three filters are connected in parallel, and the high-pass filter cutoff frequency can be changed from 350-2000MHz through switch switching.

[0016] Embodiment 2: A method for preparing a 350-2000MHz high-pass filter. After preparing a 350-690MHz filter, a 690-1250MHz filter and a 1250-2000MHz filter respectively, a conversion switch is connected to switch the frequency band. The methods for preparing the 350-690MHz filter, the 690-1250MHz filter and the 1250-2000MHz filter all adopt the following steps: S1. Ingredients: Select a material with a dielectric constant of 5.1, and ball-mill the powder into a particle size of 0.3-0.5 μm; S2, tape casting: the ingredients after ball milling are prepared into slurry, and the raw porcelain tapes of different thicknesses 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 filter design pattern of the corresponding frequency band of the high-pass filter is prepared on the film. After exposure, the inductance of the filter and the capacitor installed inside the porcelain body are transferred to the 500-mesh steel screen covered by the photosensitive adhesive (higher precision printing lines). The capacitor uses a 400-mesh steel screen to form a printing jig; by controlling the thickness of the photosensitive adhesive coating: 42μm-55μm; printing GAP value: 1mm-3mm; printing scraper pressure: 0.05MPa-0.10MPa; scraper step speed 0.01m / s-0.05m / s; each layer of the design model containing the inductor or capacitor pattern is printed on the raw porcelain tape of the corresponding thickness, the printed inductor line width error is within 1μm, 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 85±5℃; the holding time is 900s; the holding pressure is 5100±100psi, forming a Bar block; S8, cutting: divide the Bar block into independent product units of 6.95mm*4.63mm with an error of ±0.02mm; S9, debinding: Debinding the split products for 36 hours according to the staged temperature debinding curve with a dielectric constant of 5.1. The staged temperatures of the debinding curve are as follows: gradually increase the temperature from RT to 270℃ for 15h; keep constant at 270℃ for 2h; gradually increase the temperature from 270 to 320℃ for 4h; keep constant at 320℃ for 2h; gradually increase the temperature from RT to 270℃ for 5h; gradually increase the temperature from 320 to 465℃ for 4h; keep constant at 465℃ for 5h; gradually cool down from 465℃ to RT; S10, sintering: the debinding product is sintered in a tunnel furnace; the tunnel furnace belt speed is 45mm / min, there are 12 sintering temperature zones, the sintering temperature is 875℃, and the sintering time is 1h: S11, chamfering: chamfering the sintered product; 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 carried out on the silver-coated products; silver burning is carried out using a tunnel furnace; there are 6 sintering temperature zones, sintering temperature: 715℃, and holding time: 20min-25min; S14, electroplating: After silver firing, the product is electroplated with nickel, tin and lead to obtain the final product.

[0017] 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 350-2000MHz high-pass filter, characterized in that: The invention comprises a 350-690MHz filter, a 690-1250MHz filter and a 1250-2000MHz filter connected in parallel, wherein the two sections after the parallel connection are connected are connected by a conversion switch, wherein the 350-690MHz filter, the 690-1250MHz filter and the 1250-2000MHz filter each comprise a ceramic body (1), a first inductor (2), a second inductor (3), a third inductor (4), a fourth inductor (5), a first capacitor (6), a second capacitor (7), a third capacitor (8), a fourth capacitor (9) and a fifth capacitor (10), wherein the ceramic body (1) is provided with a first capacitor (6), a second capacitor (7), a third capacitor (8), a fourth capacitor (9) and a fifth capacitor (10) which are electrically connected in sequence to form a series capacitor layer, wherein the first inductor (2), the second inductor (3), the third inductor (4), The fourth inductor (5) is a three-dimensional inductor, which is arranged in the ceramic body (1) to form an inductor layer, and the formed inductor layer is located below the series capacitor layer. The input and output ends of the series capacitor layer are respectively connected to the series capacitor layer and the input pin (11) and the output pin (12) arranged at the bottom of the ceramic body (1) through the upper inner electrode (18) and the side inner electrode (19). The first inductor (2), the second inductor (3), the third inductor (4), and the fourth inductor (5) are all connected to five external capacitor connection terminals (13) at the bottom of the ceramic body (1) through the lower inner electrode (20). The five external capacitor connection terminals (13) are respectively connected to the sixth capacitor (14), the seventh capacitor (15), the eighth capacitor (16), and the ninth capacitor (17). The sixth capacitor (14), the seventh capacitor (15), the eighth capacitor (16), and the ninth capacitor (17) are variable capacitors.

2. A 350-2000MHz high-pass filter according to claim 1, characterized in that: The distance between the capacitor layer and the inductor layer is 10-40um.

3. The method for preparing a 350-2000 MHz high pass filter according to claim 1, characterized in that: The method comprises the following steps: S1. Ingredients: Select a material with a dielectric constant of 5.1, and ball-mill the powder into a particle size of 0.3-0.5 μm; S2, tape casting: the ingredients after ball milling are prepared into slurry, and the raw porcelain tapes of different thicknesses 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 filter design pattern of the corresponding frequency band of the high-pass filter is prepared on the film. After exposure, the inductance of the filter and the capacitor installed inside the porcelain body are transferred to the 500-mesh steel screen covered by the photosensitive adhesive. The capacitor uses a 400-mesh steel screen to form a printing jig; by controlling the thickness of the photosensitive adhesive coating: 42μm-55μm; printing GAP value: 1mm-3mm; printing scraper pressure: 0.05MPa-0.10MPa; scraper step speed 0.01m / s-0.05m / s; each layer of the design model containing the inductor or capacitor pattern is printed on the raw porcelain tape of the corresponding thickness, the printed inductor line width error is within 1μm, 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 85±5℃; the holding time is 900s; the holding pressure is 5100±100psi, forming a Bar block; S8, cutting: divide the Bar block into independent product units of 6.95mm*4.63mm with an error of ±0.02mm; S9, debinding: Debinding the split products for 36 hours according to the staged temperature debinding curve with a dielectric constant of 5.

1. The staged temperatures of the debinding curve are as follows: gradually increase the temperature from RT to 270℃ for 15h; keep constant at 270℃ for 2h; gradually increase the temperature from 270 to 320℃ for 4h; keep constant at 320℃ for 2h; gradually increase the temperature from RT to 270℃ for 5h; gradually increase the temperature from 320 to 465℃ for 4h; keep constant at 465℃ for 5h; gradually cool down from 465℃ to RT; S10, sintering: the debinding product is sintered in a tunnel furnace; the tunnel furnace belt speed is 45mm / min, there are 12 sintering temperature zones, the sintering temperature is 875℃, and the sintering time is 1h: S11, chamfering: chamfering the sintered product; 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 carried out on the silver-coated products; silver burning is carried out using a tunnel furnace; there are 6 sintering temperature zones, sintering temperature: 715℃, and holding time: 20min-25min; S14, electroplating: After silver firing, the product is electroplated with nickel, tin and lead to obtain the final product.

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