PCB-based circulator and its fabrication method

Abstract

The present invention provides a circulator based on a PCB board and a preparation method thereof, which belongs to the field of radio frequency devices, and includes a first substrate, a second substrate, a third substrate and a fourth substrate which are sequentially stacked from bottom to top and connected by bolts, wherein the first substrate is embedded with a ferrite block; a magnetic steel is arranged in the third substrate, and the magnetic steel is pressed by the fourth substrate. The present invention manufactures a low-cost circulator through the PCB process, which has the characteristics of low cost, low loss, small volume, high reliability, high integration, flexible design and full shielding; and the circulator prepared based on the PCB process can form resonant cavities of various shapes on the substrate, making its design more flexible; adopting threaded connection assembly to realize a fully shielded structure based on PCB, greatly reducing radiation loss; adopting a multi-layer board and cooperating with threaded fixing of magnetic steel can also solve the problem that the magnetic steel is bonded above the circulator and cannot apply lateral force at high temperature, thus expanding the use scenarios of the circulator.

Description

Technical Field

[0001] The invention belongs to the technical field of radio frequency devices, and in particular relates to a circulator based on a PCB board. Background Art

[0002] PCB (Printed Circuit Board) is a basic component used to support and connect electronic components. The circulator is an important component in the T / R component (T / R component refers to the part between the radio frequency and the antenna in a wireless transceiver system, that is, one end of the T / R component is connected to the antenna and the other end is connected to the intermediate frequency processing unit to form a wireless transceiver system). It plays the role of antenna sharing and transceiver isolation.

[0003] In the prior art, circulators have disadvantages such as high cost and complex assembly, which do not conform to the development trend of low-cost and miniaturized microwave devices, limit the popularization and wide application of circulators, and have poor practicality.

[0004] In the prior art, the magnet used to apply the magnetic field is usually installed above the circulator by bonding, which results in that a lateral force cannot be applied to the magnet at high temperatures, limiting the use scenarios of the circulator. Summary of the invention

[0005] The embodiment of the present invention provides a circulator based on a PCB board and a preparation method thereof, aiming to solve the problems of complex assembly, high assembly cost and limited use scenarios of existing circulators.

[0006] To achieve the above object, the technical solution adopted by the present invention is: to provide a method for preparing a circulator based on a PCB board, the method comprising: Preparation of the first substrate: Making air grooves on the lower surface of the first substrate; Arranging a first bolt connection hole on the first layer of substrate; Preparation of the second substrate: Arranging a second bolt connection hole on the second layer substrate; Preparation of the third substrate; A magnetic steel placement cavity is provided on the third substrate; Arrange a third bolt connection hole on the third substrate; Preparation of the fourth substrate; A fourth bolt connection hole is provided on the fourth substrate; and the upper and lower surfaces of the fourth substrate are not metallized; assembly: The first substrate, the second substrate, and the third substrate are stacked in sequence, a magnetic steel is placed in the magnetic steel placement cavity on the third substrate, and the fourth substrate is stacked; bolts are used to pass through the fourth bolt connection hole, the third bolt connection hole, the second bolt connection hole, and the first bolt connection hole from top to bottom to connect; a ferrite block is placed in the air slot to obtain a circulator chip; Solder the circulator chip to the Kovar carrier.

[0007] In conjunction with the first aspect, in one achievable manner, the preparation of the first substrate further includes: Preparing a first metallized through hole on the first substrate; Prepare a first metallization pattern on the upper surface of the first substrate to form a circuit pattern; A second metallization pattern is prepared on the lower surface of the first substrate to form a grounding layer; wherein the inner wall of the air slot is not metallized.

[0008] In combination with the first aspect, in one achievable manner, the shape of the air groove prepared on the lower surface of the first substrate is circular or polygonal by using a dielectric cutting method.

[0009] In combination with the first aspect, in one achievable manner, a first metallization pattern is prepared on the upper surface of the first substrate by electroplating; A second metallization pattern is prepared on the lower surface of the first substrate by electroplating.

[0010] In combination with the first aspect, in one achievable manner, the preparation of the second substrate further includes: preparing a second metallized through hole on the second substrate; Prepare a third metallization pattern on the upper surface of the second substrate to form a ground layer; A fourth metallization pattern is prepared on the lower surface of the second substrate, facing the first metallization pattern, to form a circuit pattern.

[0011] In combination with the first aspect, in one achievable manner, a third metallization pattern is prepared on the upper surface of the second substrate by electroplating; The fourth metallization pattern is prepared on the lower surface of the second substrate by electroplating.

[0012] In combination with the first aspect, in one achievable manner, a dielectric cutting method is used to form the magnetic steel placement cavity on the third substrate, and the shape of the magnetic steel placement cavity can be circular or polygonal.

[0013] In combination with the first aspect, in one achievable manner, the upper and lower surfaces of the third substrate are not metallized; The upper and lower surfaces of the fourth substrate are not metallized.

[0014] In the second aspect, an embodiment of the present invention further provides a circulator based on a PCB board, which is prepared by the preparation method of the circulator based on a PCB board, including a first substrate, a second substrate, a third substrate and a fourth substrate stacked in sequence from bottom to top and connected by bolts, the first substrate is embedded with a ferrite block, the lower surface of the first substrate and the lower surface of the ferrite block are provided with a second metallization pattern, the upper surface of the first substrate is provided with a first metallization pattern, the lower surface of the second substrate is provided with a fourth metallization pattern, and the upper surface of the second substrate is provided with a third metallization pattern; the third substrate is provided with a magnetic steel, and the magnetic steel is pressed by the fourth substrate.

[0015] Compared with the prior art, the circulator based on PCB board and the preparation method thereof provided by the present invention have the following beneficial effects: the bonding cost is greatly reduced by utilizing bolt connection assembly, the assembly difficulty is reduced, the integration of the circulator is improved, and the assembly is simple and the assembly cost is low. Combined with mature PCB technology, batch production can be achieved, and the production cost can be reduced. At the same time, by utilizing multi-layer PCB boards and adopting a mechanical assembly method of bolt connection to fix the magnetic steel, the problem that the adhesive magnetic steel cannot apply lateral force at high temperature is overcome, the fixing firmness of the magnetic steel and the integration of the circulator are improved, thereby expanding the wide range of use scenarios of the circulator. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A schematic diagram of the structure of a circulator based on a PCB board provided in an embodiment of the present invention; Figure 2 A schematic diagram of a processing process of a circulator based on a PCB board provided in an embodiment of the present invention; Figure 3 A schematic diagram of the assembly structure of a circulator based on a PCB board provided in an embodiment of the present invention; Figure 4 A schematic diagram of the working principle structure of a circulator based on a PCB board provided in an embodiment of the present invention; Description of reference numerals: 1. First substrate; 2. Second substrate; 3. Third substrate; 4. Fourth substrate; 5. Bolts; 6. Magnets; 7. Kovar carrier; 8. First metallized through hole; 9. Ferrite block; 10. Second metallized through hole; 11. Magnet placement cavity; 12. Air slot. DETAILED DESCRIPTION

[0017] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0018] Please also read Figures 1 to 3 , the circulator based on PCB board provided by the present invention is now described. The preparation method of the circulator based on PCB board is composed of a first layer substrate 1, a second layer substrate 2, a third layer substrate 3, and a fourth layer substrate 4 stacked up and down. The first layer substrate 1, the second layer substrate 2, the third layer substrate 3, and the fourth layer substrate 4 are all PCB boards, which are easy to process. The upper and lower surfaces of the PCB boards are both metal layers, and the middle is a dielectric layer. The circulator of the present invention uses two layers of PCB boards as the substrate structure of the circulator, such as the first layer substrate 1 and the second layer substrate 2; and uses two layers of PCB boards as the fixing structure of the magnetic steel 6. The two layers of PCB have only dielectric layers, such as the third layer substrate 3 and the fourth layer substrate 4.

[0019] The specific preparation process is as follows: 1. Preparation process of the first substrate 1: 1) A dielectric cutting method is used to cut an air groove 12 with a depth on the lower surface of the first substrate 1. The depth of the air groove 12 is adjusted according to the design, and the shape of the air groove 12 can be circular or polygonal.

[0020] 2) A dielectric removal method is used to remove a plurality of first metallized through holes 8 for the resonator and first bolt connection holes for threaded connection on the first layer substrate 1, and the first bolt connection holes are not metallized.

[0021] 3) The first metallized through hole 8 on the first layer substrate 1 is metallized by electroplating.

[0022] 4) Using an electroplating method, a first metallization pattern such as a metal circuit and a resonator is prepared on the upper surface of the first substrate 1 .

[0023] 5) A second metallization pattern is prepared on the lower surface of the first substrate 1 by electroplating as a grounding layer; wherein the etched air slots 12 are not metallized.

[0024] 2. Preparation process of the second substrate 2: 1) A dielectric removal method is used to etch a plurality of second metallized through holes 10 for the resonator and second bolt connection holes for threaded connection on the upper second layer substrate 2. The second metallized through holes 10 are opposite to the first metallized through holes 8, and the second bolt connection holes are opposite to the first bolt connection holes, in preparation for the alignment of the resonator or the bolts 5.

[0025] 2) The second metallized through hole 10 on the second layer substrate 2 is metallized by electroplating.

[0026] 3) A fourth metallization pattern such as a metal circuit and a resonator is prepared on the lower surface of the second substrate 2 by electroplating so as to face the second metallization pattern on the upper surface of the first substrate 1 .

[0027] 4) Using electroplating, a third metallization pattern is prepared on the upper surface of the second substrate 2 as a ground layer.

[0028] After being connected by bolts 5, the metallized through holes and the grounding layers of the upper and lower substrates form a fully metal-shielded cavity structure, which can reduce the radiation loss of the circulator; and the use of a double-layer substrate as a substrate structure has a higher equivalent dielectric constant than a single-layer structure, so that a small volume can be achieved at the same frequency.

[0029] The present invention has penetrating metallized through holes on the first substrate and the second substrate, which can realize the connection between the upper and lower metal layers of the single-layer board and the vertical interconnection between different board layers, and can also be used to form resonant cavities of different shapes.

[0030] 3. Preparation process of the third substrate 3: 1) A dielectric cutting method is used to cut a magnetic steel placement cavity 11 from the third substrate 3. The shape of the magnetic steel placement cavity 11 can be circular or polygonal.

[0031] 2) A dielectric cutting method is used to cut out a plurality of third bolt connection holes for threaded connection on the third substrate 3 .

[0032] 4. Preparation process of the fourth layer substrate 4: 1) A dielectric cutting method is used to cut out a plurality of fourth bolt connection holes for threaded connection on the fourth layer substrate 4 .

[0033] 5. Assembly process of low-cost circulator based on PCB: Compared with the existing installation method of bonding the magnetic steel on the top of the circulator, the present application cuts a through hole on the third substrate 3 as a magnetic steel placement cavity 11 for the subsequent magnetic steel material; the fourth substrate 4 is not cut, and serves as an upper cover for fixing the magnetic steel material. The four-layer PCB board has non-metallized through holes at the same position as bolt connection holes, which can be used for bolt connection assembly; during assembly, the magnetic steel material with the same size as the through hole of the third substrate 3 is embedded in the through hole of the third substrate 3, and the fourth substrate 4 is covered. The four substrates are assembled by threaded connection to form the basic structure of the circulator.

[0034] The present invention utilizes a multi-layer PCB board and adopts a mechanical assembly method of connecting a third substrate 3, a fourth substrate and bolts to fix the magnetic steel, thereby overcoming the problem that the adhesive magnetic steel cannot exert a lateral force at high temperature, improving the fixing firmness of the magnetic steel and the integration of the circulator, thereby expanding the use scenarios of the circulator.

[0035] See also Figure 2 The basic structure after the above process is assembled, and the ferrite block 9 that matches the size of the air slot 12 is placed in the air slot 12. The corresponding lower surface of the ferrite block 9 is metallized to form a circulator chip.

[0036] See also Figure 3 The circulator chip that has completed the above process is welded together with the Kovar carrier 7, and an external magnetic field is applied to finally form a low-cost circulator based on PCB.

[0037] in, Figure 4 This is a working principle diagram of the low-cost circulator based on PCB provided by the present invention.

[0038] Compared with the prior art, the circulator based on PCB board and the preparation method thereof provided by the present invention have the following beneficial effects: (1) The circulator is assembled by bolts 5, which greatly reduces the bonding cost, reduces the assembly difficulty, and improves the integration of the circulator. It has the characteristics of simple assembly and low assembly cost. Combined with mature PCB technology, it can realize batch production and reduce the production cost.

[0039] (2) The metallized through holes and the grounding layers of the upper and lower substrates form a fully metal-shielded cavity structure, which can reduce the radiation loss of the circulator. The use of a double-layer substrate as the substrate has a higher equivalent dielectric constant than a single-layer structure, so that a small volume can be achieved at the same frequency.

[0040] (3) In the prior art, the magnetic steel 6 for applying the magnetic field is usually installed above the circulator by bonding, which results in the inability to apply a lateral force to the magnetic steel 6 at high temperatures, limiting the use scenarios of the circulator. The present invention can fix the magnetic steel 6 by mechanical assembly through multi-layer PCB technology, thereby improving the integration of the circulator and its application scenarios.

[0041] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0042] See also Figure 1Based on the same inventive concept, the embodiment of the present application also provides a circulator based on a PCB board, which is prepared by the preparation method of the circulator based on a PCB board, including a first substrate 1, a second substrate 2, a third substrate 3 and a fourth substrate 4 which are stacked in sequence from bottom to top and connected by bolts 5, the first substrate 1 is embedded with a ferrite block 9, the lower surface of the first substrate 1 and the lower surface of the ferrite block 9 are provided with a second metallization pattern, the upper surface of the first substrate 1 is provided with a first metallization pattern, the lower surface of the second substrate 2 is provided with a fourth metallization pattern, and the upper surface of the second substrate 2 is provided with a third metallization pattern; the third substrate 3 is provided with a magnetic steel 6, and the magnetic steel 6 is pressed by the fourth substrate 4.

[0043] The present invention manufactures a low-cost circulator through a PCB process, which has the characteristics of low cost, low loss, small size, high reliability, high integration, flexible design, and full shielding; and the low-cost circulator prepared based on the PCB process can form resonant cavities of various shapes on a substrate, making its design more flexible; in addition, threaded connection assembly is adopted to realize a full-shielded structure of the low-cost circulator based on the PCB, which greatly reduces radiation loss.

[0044] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a circulator based on a PCB board, characterized in that: The method comprises: Preparation of the first substrate (1): An air groove (12) is formed on the lower surface of the first substrate (1); A first bolt connection hole is provided on the first layer substrate (1); Preparation of the second substrate (2): A second bolt connection hole is provided on the second layer substrate (2); Preparation of the third substrate (3); A magnetic steel placement cavity (11) is provided on the third substrate (3); A third bolt connection hole is provided on the third layer substrate (3); Preparation of the fourth substrate (4); A fourth bolt connection hole is provided on the fourth layer substrate (4); and the upper and lower surfaces of the fourth layer substrate (4) are not subjected to metallization treatment; assembly: The first substrate (1), the second substrate (2), and the third substrate (3) are stacked in sequence, a magnetic steel (6) is placed in a magnetic steel placement cavity (11) on the third substrate (3), and the fourth substrate (4) is stacked; bolts (5) are used to pass through the fourth bolt connection hole, the third bolt connection hole, the second bolt connection hole, and the first bolt connection hole in sequence from top to bottom to connect; a ferrite block (9) is placed in the air slot (12) to obtain a circulator chip; The circulator chip is soldered onto a Kovar carrier (7) to obtain a circulator based on a PCB board.

2. The method for preparing a circulator based on a PCB board according to claim 1, characterized in that: The preparation of the first substrate (1) further comprises: Preparing a first metallized through hole (8) on the first layer substrate (1); Preparing a first metallization pattern on the upper surface of the first substrate (1) to form a circuit pattern; A second metallization pattern is prepared on the lower surface of the first substrate (1) to form a grounding layer; wherein the inner wall of the air slot (12) is not metallized.

3. The method for preparing a circulator based on a PCB board according to claim 2, characterized in that: The shape of the air groove (12) prepared on the lower surface of the first layer substrate (1) by a dielectric cutting method is circular or polygonal.

4. The method for preparing a circulator based on a PCB board according to claim 2, characterized in that: Preparing a first metallization pattern on the upper surface of the first substrate (1) by electroplating; A second metallization pattern is prepared on the lower surface of the first substrate (1) by electroplating.

5. The method for preparing a circulator based on a PCB board according to claim 2, characterized in that: The preparation of the second substrate (2) further includes: Preparing a second metallized through hole (10) on the second substrate (2); A third metallization pattern is prepared on the upper surface of the second substrate (2) to form a grounding layer; A fourth metallization pattern is prepared on the lower surface of the second layer substrate (2) and is directly opposite to the first metallization pattern to form a circuit pattern.

6. The method for preparing a circulator based on a PCB board according to claim 5, characterized in that: Using electroplating to prepare a third metallization pattern on the upper surface of the second substrate (2); A fourth metallization pattern is prepared on the lower surface of the second substrate (2) by electroplating.

7. The method for preparing a circulator based on a PCB board according to claim 2, characterized in that: The magnetic steel placement cavity (11) is formed on the third layer substrate (3) by using a dielectric removal method. The shape of the magnetic steel placement cavity (11) can be circular or polygonal.

8. The method for preparing a circulator based on a PCB board according to claim 2, characterized in that: The upper and lower surfaces of the third substrate (3) are not subjected to metallization treatment; The upper and lower surfaces of the fourth substrate (4) are not subjected to metallization treatment.

9. A circulator based on a PCB board, prepared by the method for preparing a circulator based on a PCB board according to any one of claims 1 to 8, characterized in that: The invention comprises a first substrate (1), a second substrate (2), a third substrate (3) and a fourth substrate (4) which are stacked in sequence from bottom to top and connected by bolts (5); the first substrate (1) is embedded with a ferrite block (9); the lower surface of the first substrate (1) and the lower surface of the ferrite block (9) are provided with a second metallization pattern; the upper surface of the first substrate (1) is provided with a first metallization pattern; the lower surface of the second substrate (2) is provided with a fourth metallization pattern; and the upper surface of the second substrate (2) is provided with a third metallization pattern; the third substrate (3) is provided with a magnetic steel (6), and the magnetic steel (6) is pressed by the fourth substrate (4).

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