A surface mount device port processing method and a microstrip surface mount circulator prepared by the method

Abstract

The invention discloses a method for processing the port of a surface-mount device, and belongs to the technical field of microwave ferrite devices. The surface-mount device comprises an iron bottom plate and a ferrite substrate. The outer shape of the iron bottom plate after processing is firstly to be a shape without input and output ports, and then the processed iron bottom plate is welded to the ferrite substrate. After welding, the input and output ports of the surface-mount device are processed by a ball planting process. The invention also discloses a microstrip surface-mount circulator prepared by the above method, comprising an iron bottom plate, a ferrite substrate, matching ceramics and a permanent magnet connected in sequence, and also comprising solder balls and metallized vias. The invention greatly simplifies the traditional iron bottom plate processing structure by introducing the "ball planting" process, thereby improving the processing efficiency and increasing the yield rate. The surface-mount circulator after ball planting has more advantages in non-destructive testing, assembly with complete equipment and other links, and has the ability of mass production.

Description

Technical Field

[0001] The invention relates to the technical field of microwave ferrite devices, and in particular to a surface-mount device port processing method and a microstrip surface-mount circulator prepared by the method. Background Art

[0002] Microstrip circulators / isolators are microwave ferrite devices widely used in various microwave weapons and equipment such as phased array radars. Currently, as various types of weapons and equipment and phased array radars move towards integration and miniaturization, surface-mount microstrip devices with the advantage of integrated integration have become the preferred structure for related equipment.

[0003] The input and output ports of the traditional microstrip circulator are on the same layer as the transmission circuit, and when in use, they need to be spliced ​​with the user's transmission circuit through gold wire or other means. Although this connection method can achieve the transmission of microwave signals, it has two disadvantages: first, gold wire splicing has high requirements for operators and requires specific equipment; second, gold wire splicing requires a certain bending radius, which invisibly increases the installation size of the product.

[0004] Therefore, with the development of technology, more and more semiconductor devices are installed in the form of surface mount, that is, the input and output ports of the product are on the same surface as the ground. In this way, all semiconductor devices can be assembled by mounting machines and completed at one time through equipment such as reflow soldering. This can not only greatly reduce the time for assembling the whole machine, but also integrate all the equipment together, and the installation size can be reduced to about 50% of the original.

[0005] At present, there are many types of surface mount devices mentioned above. Taking the microstrip surface mount circulator as an example, its typical structure is as follows: Figure 1 As shown, it is composed of main parts such as iron base plate 1, ferrite substrate 2, matching ceramic 3, permanent magnet 4, etc. In order to realize the surface mount performance of the product, the transmission circuit of the ferrite substrate 2 is punched on the substrate to form a metallized via 6 to the back of the product, and is connected to the external signal line through the input and output port 5, thereby realizing the function of the surface mount circulator.

[0006] In the current process method, since the input and output ports 5 are very small, generally about 0.3mm×0.3mm~0.6mm×0.6mm, the size is extremely small, and they are independent of the iron base plate, there are great difficulties in assembly, and the yield rate is low, making it difficult to improve the research and development level and production efficiency of such devices, and there are major bottlenecks in mass production.

[0007] At present, in addition to the above-mentioned "iron base plate + ferrite substrate + matching ceramic + permanent magnet" structure, there is also a "ferrite substrate + matching ceramic + permanent magnet" structure for microstrip surface-mount circulators. The defects of these two structures are as follows:

[0008] Form 1: Iron base plate + ferrite substrate + matching ceramic + permanent magnet

[0009] Form 1 is the commonly used structural form of microstrip devices at present. For surface-mount circulators, the main difference from traditional microstrip devices is that there are metallized through holes on the ferrite substrate and input and output ports on the lower iron base plate.

[0010] In order to facilitate welding of the lower iron base plate and input and output ports, there are two traditional design solutions:

[0011] The first design scheme is to process the iron bottom plate 1 and the input and output ports 5 separately. Figure 2 As shown, after the gold plating is completed, it is placed on a precise fixture for positioning, and the iron base plate is welded to the ferrite substrate by welding;

[0012] The second design is to integrate the iron base plate and the input and output ports. Figure 3 As shown; after processing, the whole is welded to the ferrite substrate, and after welding, it is cut according to the dotted line part in the figure.

[0013] For the first design in Form 1, the size of the input and output ports 5 of the product is very small, generally about 0.3mm×0.3mm~0.6mm×0.6mm, which is difficult to process, and the dimensional accuracy of the processed product is poor, and it is not suitable for mass production. In the assembly process, due to the small size of the product, the positioning accuracy of the positioning fixture is high, the operation is extremely difficult, and it is generally rarely used in production.

[0014] The second design in Form 1 is an assembly design optimization based on the first design. By processing the iron bottom plate and the input and output ports as one, the processing and assembly can be made simpler. However, after the product is assembled, the excess parts need to be cut off. This has two main defects:

[0015] 1. The product needs to be cut after welding. Due to the extremely small size of the input and output ports, it is very easy to pull off the small iron block at the product port during the cutting process, which directly causes the product to be scrapped. The yield rate of this structural form is about 60-80%, which is not suitable for mass production of products;

[0016] 2. The iron base plate of the product is generally gold-plated, and the cross-section of the product after cutting is exposed pure iron, which is very easy to rust when used in the air for a long time, affecting the reliability of the product.

[0017] Form 2: Ferrite substrate + matching ceramic + permanent magnet

[0018] In order to solve the problem that the iron base plate in form 1 is difficult to process, the thickness of the ferrite is increased by about 0.2mm in the design to replace the iron base plate in the original design. Figure 4 As shown in the figure, the input and output ports are formed on the back of the ferrite by sputtering. There are two main defects in this form:

[0019] 1. After adding ferrite materials, the impedance of the upper circuit will increase significantly. In order to meet the impedance requirements of the early design line, the width of the transmission line needs to be appropriately increased. Generally, if the substrate thickness increases by 0.2mm, the product line width increases by about 65-75%. After compact processing, the designed product size increases by about 40%-60% compared with the initial product size, which greatly increases the installation size of the product and does not meet the technical development trend of miniaturization of complete equipment;

[0020] 2. Since the iron base plate is eliminated, the uniformity of the magnetic field on the ferrite substrate is greatly reduced, and the microwave performance of the product will also be reduced to a certain extent. Especially for products with a bandwidth exceeding 10%, the performance of the product is seriously deteriorated and does not meet the technical development requirements of broadband equipment. Summary of the invention

[0021] One of the purposes of the present invention is to provide a surface mount device port processing method to solve the above-mentioned surface mount device assembly difficulty and low yield problem.

[0022] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is as follows: a method for processing the ports of a surface-mount device, wherein the surface-mount device includes an iron base plate and a ferrite substrate, the iron base plate is first processed into a shape without input and output ports, and then the processed iron base plate is welded to the ferrite substrate. After welding, the input and output ports of the surface-mount device are processed using a ball planting process.

[0023] The ball implantation scheme for the input and output ports of the surface-mount devices such as microstrip surface-mount circulators proposed by the present invention can make the iron base plate processing of the product more convenient, and has a fast ball implantation efficiency and a high yield rate, and can be used in large quantities in batch products.

[0024] The iron bottom plate processing method of the present invention includes but is not limited to existing wire cutting or etching, so as to obtain the shape of the iron bottom plate without the input and output ports.

[0025] The method of the invention is applicable to the port processing of a surface-mounted circulator / isolator made of dielectric materials such as ceramics, organic glass, PCB, Si, GaAs, etc. with ferrite functional materials and an iron bottom plate structure.

[0026] The novel port processing method proposed by the present invention is applicable to the port processing of all ferrite surface mounted devices. The port positions include but are not limited to the device edge. Any position at the top and bottom of the device can be applicable to this method.

[0027] The second object of the present invention is to provide a microstrip surface-mount circulator made by the above-mentioned processing method, comprising an iron base plate, a ferrite substrate, matching ceramics and a permanent magnet connected in sequence, and also comprising solder balls and metallized vias. A surface circuit is arranged on the ferrite substrate, and the solder balls are connected to the surface circuit of the ferrite substrate through the metallized vias.

[0028] Compared with the prior art, the advantages of the present invention are:

[0029] 1. The ball planting process can make the iron base plate structure simple and greatly reduce the processing difficulty;

[0030] 2. The ball planting process replaces the traditional small iron block design of the port, which improves the work efficiency by more than 50 times and the yield rate can be increased from the previous 60-80% to more than 99.5%;

[0031] 3. After the product is implanted, the height of the ball will be slightly higher than the height of the iron base plate by about 0.1 to 0.15 mm. Figure 7 As shown in the figure, this is more conducive to non-destructive testing in the later stage. The solder ball itself is relatively soft. During the test, the slight deformation of the solder ball end surface can better ensure the tightness of the test connection. The test time can be shortened to 1 / 5 to 1 / 10 of the test time of traditional devices.

[0032] 4. The product port is composed of solder balls. Even if there is insufficient solder at the user's port during heating, the welding quality with the user's connecting board can be guaranteed, and the reliability is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is a schematic diagram of a typical existing microstrip surface-mount circulator structure;

[0034] Figure 2 A schematic diagram of one of the iron bottom plate processing solutions in the prior art;

[0035] Figure 3 It is a schematic diagram of another iron bottom plate processing solution in the prior art;

[0036] Figure 4 It is a structural schematic diagram of a microstrip surface-mount circulator without an iron bottom plate in the prior art;

[0037] Figure 5 This is a schematic diagram of the processing structure of the iron bottom plate according to an embodiment of the present invention;

[0038] Figure 6A schematic diagram of the structure of a microstrip surface-mount circulator according to an embodiment of the present invention;

[0039] Figure 7 for Figure 6 Enlarged view of the side portion.

[0040] In the figure: 1. Iron base plate; 2. Ferrite substrate; 3. Matching ceramic; 4. Permanent magnet; 5. Input and output ports; 6. Solder ball; 7. Metallized via. DETAILED DESCRIPTION

[0041] The present invention will be further described below in conjunction with the accompanying drawings.

[0042] Example:

[0043] This embodiment takes a microstrip surface-mount circulator as an example to illustrate a surface-mount circulator port processing method, wherein the surface-mount circulator includes an iron base plate, a ferrite substrate, matching ceramics and a permanent magnet, wherein the processing method of the ferrite substrate, the matching ceramics and the permanent magnet is still the traditional processing method, and the improvement lies in the processing method of the iron base plate, which is processed by a wire cutting method. The shape of the iron base plate after processing is the shape of the input and output ports removed, such as Figure 5 As shown, the processed iron bottom plate is then welded to the ferrite substrate. After welding, a conventional ball planting process (similar to the "BGA ball planting" process) in the field of electronic semiconductors is used to plant balls on the input and output ports of the surface mount device.

[0044] The microstrip surface mount circulator prepared by the above processing method has a structure as shown in Figure 6 and 7 As shown, it includes an iron base plate 1, a ferrite substrate 2, a matching ceramic 3 and a permanent magnet 4 connected in sequence, and also includes a solder ball 6 and a metallized via 7. A surface circuit is set on the ferrite substrate 2, and the solder ball 6 is connected to the surface circuit of the ferrite substrate 2 through the metallized via 7.

[0045] The present invention proposes a novel processing method for the port of a microstrip surface mount circulator. By introducing the "ball planting" process, the traditional iron base plate processing structure is greatly simplified, which improves the processing efficiency and also increases the yield rate. The surface mount circulator after ball planting has more advantages in non-destructive testing and assembly with complete equipment, and has the ability to be mass-produced. In the later stage, a specific ball planting machine can also be introduced to carry out ball planting of the port of the microstrip surface mount circulator, so as to make the production efficiency more efficient and achieve the purpose of intelligent production.

[0046] 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 microstrip surface mount circulator port processing method, characterized in that: The method comprises: firstly processing the iron base plate, the shape after processing is the shape without the input and output ports, then welding the processed iron base plate to the ferrite substrate, and after welding, processing the input and output ports of the microstrip surface mount circulator by using a ball planting process; the microstrip surface mount circulator comprises an iron base plate, a ferrite substrate, matching ceramics and a permanent magnet connected in sequence, and also comprises a solder ball and a metallized via hole, a surface circuit is arranged on the ferrite substrate, and the solder ball is connected to the surface circuit of the ferrite substrate through the metallized via hole.

2. The method according to claim 1, characterized in that: The iron bottom plate is processed by wire cutting or etching.

3. The method according to claim 1, characterized in that: The microstrip surface-mount circulator is a surface-mount circulator made of ceramic, organic glass, PCB, Si, and GaAs dielectric materials with ferrite functional materials and an iron bottom plate structure.

4. The method according to claim 1, characterized in that: The input and output ports are located at any position of the edge, top or bottom of the microstrip surface mount circulator.

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