Processing method of dielectric ceramic filter and dielectric ceramic filter

Abstract

The invention relates to a processing method of a dielectric ceramic filter and the dielectric ceramic filter, and the method comprises the steps: S1, carrying out the dry pressing of dielectric substrate powder, forming a dielectric blank, setting a marking point on the dielectric blank, and forming the dielectric blank with the marking point; carrying out high-temperature sintering on the medium blank, unifying the placing direction of the medium blank in the process so as to enable the mark points on the placed medium blank to be in the same direction, and then carrying out high-temperature sintering on the medium blank to form a medium matrix; s2, performing surface metallization treatment on the dielectric substrate to form a conductive layer on the surface of the dielectric substrate; and S3, carrying out first size processing on the dielectric substrate so as to adjust the size of the resonance hole to a specified size. According to the invention, the stability of the frequency of the filter can be improved, the dimensional deviation of the dielectric substrate is reduced, the input cost of production and debugging is reduced, the qualified rate of products is improved, and the consistency of the production process and the product performance are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of manufacturing dielectric ceramic filters, and in particular to a processing method for dielectric ceramic filters and a dielectric ceramic filter. Background Art

[0002] A dielectric ceramic filter is a filter based on ceramic materials, mainly used in radio frequency (RF) and microwave communication fields. Dielectric ceramics are ceramic materials with high dielectric constant, low loss, and good temperature stability, suitable for high-frequency applications. The working principle of a dielectric ceramic filter is to use the high dielectric constant and low loss of the dielectric ceramic to filter out unwanted frequencies through a resonant structure, thereby retaining the target signal. Dielectric ceramic filters are widely used in fields such as communication, radar, and wireless devices due to their high performance and miniaturization characteristics. In the prior art, the substrate of a dielectric ceramic filter is generally directly assembled after printing.

[0003] The deficiencies of the prior art are that the products produced and processed by the existing methods have a large deviation from the standard frequency, the product consistency is poor, manual debugging is required, the product qualification rate is low, resulting in waste of process resources and high production costs. Summary of the Invention

[0004] To this end, the technical problem to be solved by the present invention is to overcome the deficiencies in the prior art, and provide a processing method for dielectric ceramic filters and a dielectric ceramic filter, which can improve the frequency stability of the filter, reduce the dimensional deviation of the dielectric substrate, reduce the input costs of production and debugging, improve the product qualification rate, and improve the consistency of the production process and product performance.

[0005] To solve the above technical problem, the present invention provides a processing method for a dielectric ceramic filter, including: Step S1, obtaining dielectric substrate powder, dry-pressing the dielectric substrate powder to form a dielectric embryo, and during the dry-pressing process, setting marking points on the dielectric embryo to form the dielectric embryo with marking points; Performing high-temperature sintering on the dielectric embryo. During this process, unifying the placement direction of the dielectric embryo so that the marking points on the placed dielectric embryo are in the same direction, and then performing high-temperature sintering on the dielectric embryo to form a dielectric substrate; Step S2, performing surface metallization treatment on the dielectric substrate to form a conductive layer on the surface of the dielectric substrate; Step S3, performing first-dimensional processing on the dielectric substrate to adjust the size of the resonant holes to the standard size; Wherein, when the number of the medium substrates is greater than or equal to a specified number, batch size processing is performed according to a specified gradient value to form standard-size medium substrates and at least one gradient-size medium substrate; Step S4: Perform a first frequency selection on the standard-size medium substrates and at least one of the gradient-size medium substrates. Screen out first medium substrates that meet the specified frequency, first medium substrates higher than the specified frequency, and first medium substrates lower than the specified frequency from the standard-size medium substrates; Screen out second medium substrates that meet the specified frequency, second medium substrates higher than the specified frequency, and second medium substrates lower than the specified frequency from at least one of the gradient-size medium substrates; Step S5: Form a filter circuit by screen printing. The printing sequence is as follows: First, print on the first medium substrates lower than the specified frequency, then print on the first medium substrates that meet the specified frequency, and then print on the first medium substrates higher than the specified frequency; Next, print on the second medium substrates lower than the specified frequency, then print on the second medium substrates that meet the specified frequency, and then print on the second medium substrates higher than the specified frequency; thereby forming multiple dielectric filters; Step S6: Perform a second frequency selection on the multiple dielectric filters formed in Step S5, screen out the dielectric filters with frequencies lower than the target frequency, and perform a second size processing on them to make them reach the target frequency; Step S7: Perform assembly and debugging to make the dielectric filter meet the specified standard.

[0006] In an embodiment of the present invention, in Step S1, in the dry pressing and forming stage, a mold is used to press one end face of the dielectric blank to form a marking groove, that is, the marking point.

[0007] In an embodiment of the present invention, in Step S1, during the high-temperature sintering process, the dielectric blank is placed on a bearing plate with the end face where the marking point is located facing upward.

[0008] In an embodiment of the present invention, in Step S3, during the first size processing, the opposite face of the end face where the marking point is located is selected as the size processing face for processing.

[0009] In an embodiment of the present invention, in the step S3, during the first size processing, a first-size dielectric substrate and a second-size dielectric substrate are obtained through gradient grinding, and the gradient value is 0.01 - 0.02 mm; the size of the first-size dielectric substrate is smaller than that of the standard-size dielectric substrate, and the size of the second-size dielectric substrate is smaller than that of the first-size dielectric substrate.

[0010] In an embodiment of the present invention, in the step S6, during the second frequency selection, dielectric filters with a frequency deviation > ±0.5% are screened out. Among the screened dielectric filters, those with a frequency higher than the target frequency are eliminated, and the dielectric filters with a frequency lower than the target frequency are subjected to a second size processing.

[0011] In an embodiment of the present invention, in the step S3, the method of the first size processing includes performing size processing on the depth of the resonant holes of the dielectric substrate.

[0012] In an embodiment of the present invention, in the step S2, the metallization treatment method includes a silver dipping or silver spraying process.

[0013] The present invention also provides a dielectric ceramic filter, which is manufactured by using the processing method of a dielectric ceramic filter as described above.

[0014] The above technical solution of the present invention has the following advantages compared with the prior art: A processing method of a dielectric ceramic filter according to the present invention manufactures and processes a dielectric ceramic filter through steps of dry pressing forming, high-temperature sintering, surface metallization, size processing, printed circuit, and assembly and debugging, and can effectively improve the frequency stability of the dielectric ceramic filter and at the same time improve the qualified rate of products. Among them, a dielectric matrix with marking points is formed in the dry pressing forming stage, so that it is convenient to uniformly place the direction during high-temperature sintering and reduce size problems caused by shrinkage differences; during mass production, size processing is carried out according to a specified gradient to compensate for the frequency deviation caused by the change of screen tension during printed circuit; before the circuit printing step, the dielectric matrix is subjected to the first frequency selection, so that the dielectric matrices with large frequency differences can be classified and processed, improving the consistency of subsequent processes. Since marking points are set in the dry pressing forming step, operators can unify the circuit printing end face according to the position of the marking points, which is beneficial to the consistency of printed circuits and improves the frequency stability; for the dielectric matrix after printed circuit, the second frequency selection is carried out, and its frequency data is obtained through frequency testing, and the dielectric matrix with a frequency lower than the target frequency is subjected to the second size processing to increase its frequency to reach the target frequency; in this way, the debugging time of products can be reduced, and in addition, the waste of raw materials can be effectively reduced, the qualified rate of products can be improved, and the input of production costs can be reduced. Brief Description of the Drawings

[0015] In order to make the content of the present invention easier to be clearly understood, the following further details the present invention according to specific embodiments of the present invention in conjunction with the accompanying drawings, wherein.

[0016] Figure 1 is a process flow chart of a preferred embodiment of the present invention. Detailed Embodiments

[0017] The following further illustrates the present invention in conjunction with the accompanying drawings and specific embodiments, so that those skilled in the art can better understand the present invention and can implement it, but the embodiments cited do not limit the present invention. Embodiment 1

[0018] Referring to Figure 1 as shown, the present invention discloses a processing method of a dielectric ceramic filter, including, Step S1, obtaining dielectric substrate powder, dry pressing the dielectric substrate powder to form a dielectric embryo, wherein, during the dry pressing forming process, marking points are set on the dielectric embryo, thereby forming the dielectric embryo with marking points.

[0019] In this embodiment, the dielectric substrate powder is selected as ceramic powder.

[0020] The formed medium blank is subjected to high-temperature sintering. Of course, in the actual production process, multiple medium blanks are produced in batches. During this process, the placement directions of the multiple medium blanks need to be unified. Since in the previous step, marking points are formed on the medium blank, it is convenient for the operator to place the medium blank according to the positions of the marking points, so that the marking points on the placed medium blank are in the same direction; then, the medium blank is subjected to high-temperature sintering to form a medium substrate.

[0021] It should be noted that during the high-temperature sintering process, there are slight differences in the shrinkage deformations of the surface and non-contact surfaces of the medium blank in contact with the bearing plate, resulting in differences in dimensions during subsequent processing. In this way, ensuring the consistency of the placement position of the medium blank during high-temperature sintering can ensure the identity of the processing surface during the subsequent processing, and further reduce the adverse effects caused by dimensional differences; Step S2, perform surface metallization treatment on the medium substrate to form a conductive layer on the surface of the medium substrate.

[0022] Step S3, perform the first dimensional processing on the medium substrate to adjust the size of the resonant holes to the standard size; When the number of the medium substrates is greater than or equal to the specified number, perform batch descending dimensional processing according to the specified gradient value to form a standard-size medium substrate and at least one gradient-size medium substrate; Step S4, perform the first frequency selection on the standard-size medium substrate, measure it with a frequency tester, and screen out the first medium substrates that meet the specified frequency, the first medium substrates higher than the specified frequency, and the first medium substrates lower than the specified frequency; Correspondingly, perform the first frequency selection on at least one of the gradient-size medium substrates, measure it with a frequency tester, and screen out the second medium substrates that meet the specified frequency, the second medium substrates higher than the specified frequency, and the second medium substrates lower than the specified frequency; Step S5, print a filter circuit on the medium substrate through the screen printing process. The printing sequence is: First, print on the first medium substrates lower than the specified frequency, then print on the first medium substrates that meet the specified frequency, and then print on the first medium substrates higher than the specified frequency; Next, print on the second medium substrates lower than the specified frequency, then print on the second medium substrates that meet the specified frequency, and then print on the second medium substrates higher than the specified frequency; Thus, a plurality of dielectric filters are formed. It can be seen that in the processing method of the present invention, for the printing principle of the filter circuit, under the same conditions, the circuit printing is carried out in the order of increasing frequency.

[0023] It should be explained that based on the physical properties of the screen structure itself, as the number of circuit printing increases, the tension of the screen will gradually decrease. As a result, the printed circuit will become wider, the silver layer area will become larger, and the coupling capacitance formed between the silver layer and the grounding end will become larger. Thus, under the same conditions, the resonance frequency of the dielectric filter will gradually decrease. Therefore, based on this change trend, in the circuit printing step of step S5, the dielectric substrate is printed with circuits in the order of increasing frequency to compensate for the circuit deformation caused by the attenuation of the screen tension, thereby offsetting the frequency shift to a certain extent and effectively improving the product qualification rate.

[0024] Of course, by analogy, in some other embodiments, according to different product requirements, third dielectric substrates, fourth dielectric substrates... with size gradients can also be formed by size processing. Step S6: Perform a second frequency selection on the plurality of dielectric filters in step S5. Measure the resonance frequency of the dielectric filters with a frequency tester, and screen out the dielectric filters with frequencies lower than the target frequency. Then, perform a second size processing on the dielectric filters with frequencies lower than the target frequency to enable them to reach the target frequency. Thereby reducing the manual debugging time by 50% and being able to increase the comprehensive qualification rate to over 95%.

[0025] Step S7: Perform assembly and debugging to make the dielectric filter meet the factory standards.

[0026] It can be known therefrom that a processing method of a dielectric ceramic filter to be protected by the present invention manufactures and processes a dielectric ceramic filter through steps of dry pressing, high-temperature sintering, surface metallization, size processing, printed circuit, and assembly and debugging, and can effectively improve the frequency stability of the dielectric ceramic filter and at the same time improve the qualified rate of products. Among them, in the dry pressing stage, a dielectric matrix with marking points is formed, so as to facilitate the unified placement direction during high-temperature sintering and reduce size problems caused by shrinkage differences; during mass production, size processing is carried out according to a specified gradient to compensate for the frequency deviation caused by the change of screen tension during printed circuit; before the circuit printing step, the dielectric matrix is subjected to the first frequency selection, so as to be able to classify and process dielectric matrices with large frequency differences and improve the consistency of subsequent processes. Since marking points are set in the dry pressing step, operators can unify the circuit printing end face according to the position of the marking points, which is beneficial to the consistency of printed circuits and improves the frequency stability; for the dielectric matrix after printed circuit, the second frequency selection is carried out, and its frequency data is obtained by testing its frequency. The dielectric matrix with a frequency lower than the target frequency is subjected to the second size processing to increase its frequency to reach the target frequency; in this way, the debugging time of products can be reduced. In addition, it can effectively reduce the waste of raw materials, improve the qualified rate of products, and reduce the input of production costs.

[0027] As a preferred implementation manner, in the step S1, in the dry pressing stage, by using a mold with a preset marking protrusion thereon, when dry pressing is carried out by using the mold, a marking groove can be formed on one end face of the dielectric embryo, that is, the marking point is formed. Preferably, a groove with a depth of 0.2 mm is pressed on the end face of the dielectric embryo as the marking point.

[0028] Of course, in some other implementation manners, the marking point can also adopt other structures, including but not limited to bump or groove structures; and the position of the marking point can also be adjusted according to needs as long as the subsequent processing rules can adapt to it.

[0029] As a preferred implementation manner, in the step S1, during the high-temperature sintering process, the dielectric embryo is placed on a carrier plate with the end face where the marking point is located facing upward. In this embodiment, the surface opposite to the end face with the marking point is selected as the subsequent circuit printing surface, and a circuit is printed on the circuit printing surface. Since in the subsequent process, the size of the dielectric matrix also needs to be processed, that is, the circuit printing surface is ground, placing the end face where the marking point is located upward on the carrier plate can protect the end face where the marking point is located and prevent this end face from contacting the carrier plate and being contaminated by impurities during the high-temperature sintering process.

[0030] Specifically, in this embodiment, since the surface opposite to the end face where the marked point is located is selected as the circuit printing surface, during the metallization process, the circuit printing surface can be avoided to save metal materials.

[0031] As a preferred implementation manner, in the step S3, during the first size processing, by gradient grinding, a first-size dielectric substrate and a second-size dielectric substrate are obtained, and the gradient value is 0.01 - 0.02 mm. Among them, the size of the first-size dielectric substrate is smaller than that of the standard-size dielectric substrate, and the size of the second-size dielectric substrate is smaller than that of the first-size dielectric substrate.

[0032] For example, in one implementation manner, the number of the dielectric embryos is 3000, the standard size is set to 5 mm, and the gradient step is set to 0.01 mm; through the grinding process, 1000 dielectric embryos with the standard size, 1000 dielectric embryos with a size of 4.99 mm (i.e., the first-size dielectric substrate), and 1000 dielectric embryos with a size of 4.98 mm (i.e., the second-size dielectric substrate) are processed and manufactured.

[0033] Of course, in some other implementation manners, according to the differences in production quantity and precision requirements, more processing size gradients can be set to improve the processing precision of the frequency.

[0034] Further, in the step S6, during the second frequency selection, dielectric filters with a frequency deviation > ±0.5% are screened out. Among the screened dielectric filters, the dielectric filters with a frequency higher than the target frequency are eliminated, and the dielectric filters with a frequency lower than the target frequency are subjected to the second size processing. In this way, the ineffective printing and assembly costs can be reduced, thereby reducing the production cost; and for the dielectric filters with a frequency lower than the target frequency, rework processing is performed to avoid waste of raw materials.

[0035] In terms of details, a Keysight N5221B network analyzer is used for frequency selection, and the test frequency band is 1.8 - 2.2 GHz.

[0036] Even further, in the step S3, the manner of the first size processing includes grinding the dielectric substrate so that the depth of the resonant holes of the dielectric substrate reaches the specified size.

[0037] In terms of details, in the step S2, the metallization processing method includes silver immersion or silver spraying process.

[0038] As a preferred embodiment, in the step S6, the method of the second dimension processing includes grinding the dielectric filter by a grinding device such as a machine tool to adjust the depth of the resonant holes of the dielectric substrate, so that the frequency of the dielectric substrate can reach the target frequency. Embodiment 2

[0039] The present invention also discloses a dielectric ceramic filter, which is manufactured by using the processing method of a dielectric ceramic filter as described in Embodiment 1. The obtained dielectric ceramic filter has good stability, high precision of product size, and the performance of the product can also be guaranteed.

[0040] In the description of the present invention, it should be understood that the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality" means two or more, unless otherwise specifically defined.

[0041] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and other terms should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium; it may be the internal communication of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0042] Obviously, the above embodiments are only examples given for clear illustration and are not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation manners here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. A processing method of a dielectric ceramic filter, characterized in that: Including, Step S1: Obtain the dielectric substrate powder, dry-press the dielectric substrate powder to form a dielectric embryo. During the dry-pressing process, set marking points on the dielectric embryo to form the dielectric embryo with marking points; Perform high-temperature sintering on the dielectric embryo. During this process, unify the placement direction of the dielectric embryo so that the marking points on the placed dielectric embryo are in the same direction. Then, perform high-temperature sintering on the dielectric embryo to form a dielectric substrate; Step S2: Perform surface metallization treatment on the dielectric substrate to form a conductive layer on the surface of the dielectric substrate; Step S3: Perform first-size processing on the dielectric substrate to adjust the size of the resonant holes to the standard size; Wherein, when the number of the dielectric substrates is greater than or equal to the specified number, perform batch-size processing according to the specified gradient value to form standard-size dielectric substrates and at least one gradient-size dielectric substrate; Step S4: Perform first frequency selection on the standard-size dielectric substrates and at least one of the gradient-size dielectric substrates, Screen out the first dielectric substrates that meet the specified frequency, the first dielectric substrates higher than the specified frequency, and the first dielectric substrates lower than the specified frequency from the standard-size dielectric substrates; Screen out the second dielectric substrates that meet the specified frequency, the second dielectric substrates higher than the specified frequency, and the second dielectric substrates lower than the specified frequency from at least one of the gradient-size dielectric substrates; Step S5: Form a filter circuit by screen printing. The printing sequence is: First, print on the first dielectric substrates lower than the specified frequency, then print on the first dielectric substrates that meet the specified frequency, and then print on the first dielectric substrates higher than the specified frequency; Next, print on the second dielectric substrates lower than the specified frequency, then print on the second dielectric substrates that meet the specified frequency, and then print on the second dielectric substrates higher than the specified frequency; to form multiple dielectric filters; Step S6: Perform second frequency selection on the multiple dielectric filters formed in Step S5, screen out the dielectric filters with frequencies lower than the target frequency, and perform second-size processing on them to make them reach the target frequency; Step S7: Perform assembly and debugging to make the dielectric filter meet the specified standard.

2. The processing method of a dielectric ceramic filter according to claim 1, characterized in that: In Step S1, during the dry-pressing stage, press one end face of the dielectric embryo through a mold to form a marking groove, that is, the marking point.

3. The processing method of a dielectric ceramic filter according to claim 1, wherein: In Step S1, during the high-temperature sintering process, place the dielectric embryo on a bearing plate and place the end face where the marking point is located facing up.

4. The processing method of a dielectric ceramic filter according to claim 1, characterized in that: In Step S3, during the first-size processing, select the opposite face of the end face where the marking point is located as the size processing face for processing.

5. The processing method of a dielectric ceramic filter according to claim 1, characterized in that: In the step S3, during the first size processing, a first-size dielectric substrate and a second-size dielectric substrate are obtained by gradient grinding, and the gradient value is 0.01 - 0.02 mm; the size of the first-size dielectric substrate is smaller than that of the standard-size dielectric substrate, and the size of the second-size dielectric substrate is smaller than that of the first-size dielectric substrate.

6. The processing method of a dielectric ceramic filter according to claim 1, characterized in that: In the step S6, during the second frequency selection, dielectric filters with a frequency deviation > ±0.5% are screened out. Among the screened dielectric filters, those with a frequency higher than the target frequency are eliminated, and the dielectric filters with a frequency lower than the target frequency are subjected to the second size processing.

7. The processing method of a dielectric ceramic filter according to claim 1, characterized in that: In the step S3, the manner of the first size processing includes performing size processing on the depth of the resonant holes of the dielectric substrate.

8. The processing method of a dielectric ceramic filter according to claim 1, characterized in that: In the step S2, the metallization treatment method includes a silver dipping or silver spraying process.

9. A dielectric ceramic filter, characterized in that: It is processed and manufactured by using the processing method of a dielectric ceramic filter described in any one of claims 1 - 8.

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