Processing method of ferrite substrate for subminiature waveguide device

Abstract

The invention discloses a processing method of a ferrite substrate for a subminiature waveguide device, which belongs to the technical field of microwaves and comprises the following steps of: wrapping resin and other materials with bonding and curing effects on the periphery of a ferrite workpiece to obtain a composite block body, cutting the composite block body, grinding and polishing the composite block body, removing tough materials and the like. By the adoption of the method, the substrate with the minimum phi 1 * 0.4 mm can be ground and polished, the surface roughness after polishing is 20 nm, the thickness tolerance is + / -0.005 mm, and therefore the batch percent of pass is effectively increased to 60% or above.

Description

Technical Field

[0001] The invention relates to the field of microwave technology, and in particular to a method for processing a ferrite substrate for an ultra-small waveguide device. Background Art

[0002] At present, the development direction of microwave ferrite devices is miniaturization, integration, lightweight and high quality. Therefore, various means are gradually adopted in the design of waveguide devices to improve device performance. The main technical means is to reduce the surface roughness of the substrate and control the batch thickness tolerance of the substrate by grinding and polishing the substrate. However, the characteristics of waveguide substrates are small and thin, with an outer diameter ranging from 1 to 4 mm, a thickness ranging from 0.4 to 0.6 mm, and an allowable deviation of batch thickness within 0.01 mm. Even if special fixtures are used, this type of substrate is still easily damaged during double-sided grinding and difficult to polish. According to statistics, the qualified rate of this type of special substrate for waveguide is generally less than 30%, and the qualified rate of substrates below φ2 mm is less than 10%.

[0003] The applicant's previous application CN117484693A, a method for solving the problem of fragile edges during ultra-thin processing of ferrite substrates, discloses a method for processing ferrite substrates; however, the processing method disclosed in the patent application is applied to thin film substrate processing, and the processed substrate is characterized by being fragile, large in area, and having a thickness tolerance of about 0.03 mm; while the ferrite substrate processed by the present invention is applied to waveguide devices, and the substrate is characterized by being small in area, having very high thickness tolerance requirements, and having a thickness deviation of less than 0.01 mm. That is, it is difficult to meet the processing requirements for the ferrite substrate for ultra-small waveguide devices of the present application by using the method disclosed in the patent application. The ratio of epoxy resin to curing agent in the patent is 2:1, the disc is easy to fall off, and the resin is soft and easy to deform.

[0004] In addition, using the current method, a planetary wheel needs to be equipped with 200-300 discs. Figure 3 As shown, the planetary wheel is a fixture used for processing. The smaller the substrate, the smaller and denser the holes on each planetary wheel. The processing process is cumbersome, inefficient and costly. Summary of the invention

[0005] The object of the present invention is to provide a method for processing a ferrite substrate for an ultra-small waveguide device to solve the above-mentioned problems.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is as follows: a method for processing a ferrite substrate for an ultra-small waveguide device, comprising the following steps: (1) Making a composite block: gluing the uncut ferrite material in a columnar state to a chassis and wrapping it around with a thermosetting resin material to obtain a composite block; (2) Cutting the composite block: cutting the composite block obtained in step (1) to obtain a ferrite substrate having four sides wrapped with a thermosetting resin material; (3) Grinding and polishing: Grinding the ferrite substrate obtained in step (2) to achieve the target thickness and surface roughness; (4) Removal of thermosetting resin material: removing the thermosetting resin material around the ferrite substrate to obtain the target ferrite substrate.

[0007] As a preferred technical solution, in step (1), the thermosetting resin material is selected from phenolic resin and polyurethane.

[0008] As a preferred technical solution, in step (3), the grinding method is to use a cast iron grinding wheel and a white corundum grinding liquid for grinding.

[0009] As a further preferred technical solution, the particle size of the white corundum is 10 μm. The particle size of the abrasive directly affects the surface roughness of the substrate after processing, and the selection of the abrasive particle size is determined according to the customer's requirements for the substrate.

[0010] As a preferred technical solution, in step (3), after grinding, polishing is also performed. If the device to which the obtained ferrite substrate is applied requires low loss, the ferrite sheet also needs to be polished.

[0011] As a further preferred technical solution, the polishing method is to use a polyurethane polishing pad in combination with a 1 μm white corundum polishing liquid to polish to achieve a mirror surface.

[0012] As a preferred technical solution, in step (4), the method for removing the thermosetting resin material is to heat the ferrite sheet to 400° C. to burn out the resin.

[0013] Before fixing and slicing the substrate, the substrate is fixed vertically on a glass plate to ensure the verticality of the round rod during the injection molding and slicing process and the roundness of the final substrate; then a high-hardness, high-viscosity thermosetting resin is used to wrap the round rod, which is used to stick multiple small cylinders together for processing, and in order to ensure that all small discs have the same thickness, the resin used for fixing should not be easily deformed and can play a limiting role; the present invention also uses the thermosetting resin as a supporting pressure divider to protect the small substrate from being broken due to pressure changes during the operation of the equipment.

[0014] Compared with the prior art, the advantages of the present invention are: by adopting the method of the present invention, the thickness of ferrite discs with a diameter of 1 to 4 mm for waveguide devices can be processed, and the batch thickness deviation can be guaranteed to be within 0.01 mm (the tolerance is ±0.005, that is, the batch thickness difference does not exceed 0.01 mm), which can effectively improve the batch qualification rate and increase its qualification rate from less than 30% to more than 60%; it can realize the surface treatment of ultra-small materials, and compared with the existing slicing method, the material surface consistency is better, and special models can be polished to achieve a mirror surface; in addition, by adopting the method of the present invention, only about 20 discs need to be placed on a planetary wheel, so that it is easy to observe whether there is a problem with the placement of the workpiece, deal with the substrate with placement problems, and prevent the substrate from detaching from the planetary wheel during the processing process. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a structural diagram of a composite block according to Example 1 of the present invention; Figure 2 This is a processing diagram of Example 1 of the present invention; Figure 3 This is a schematic diagram of the planetary wheel.

[0016] In the figure: 1. polyurethane; 2. ferrite column; 3. chassis; 4. ferrite substrate. DETAILED DESCRIPTION

[0017] The present invention will be further described below in conjunction with embodiments.

[0018] Example

[0019] See also Figure 1 A method for processing a ferrite substrate for an ultra-small waveguide device comprises the following steps: firstly, a ferrite column 2 is vertically glued to a chassis 3, then the ferrite column 2 and the chassis 3 are embedded with polyurethane 1, then the ferrite column 2 and the chassis 3 are cut into thin slices, and then the slices are ground with a planetary wheel to obtain a ferrite substrate. Figure 2 The composite sheet shown, and then removing the polyurethane 1, to obtain the ferrite substrate 4; This embodiment takes the processing of a ferrite substrate with a diameter of φ2*0.4mm and a tolerance of ±0.005mm that needs to be polished as an example, and the processing method is as follows: (1) Prepare an injection molding agent by mixing polyurethane AB water (commercially available) with a mass ratio of 1:1 between polyurethane and curing agent. Use glue to glue a φ2*15mm ferrite column to a glass bottom plate and let it stand upright. Then put the bottom plate 3 and ferrite column 2 into a φ30*20mm mold, inject the injection molding agent, wait for 10 hours, and take the polyurethane out of the mold after it is cured. Figure 1 The composite block shown; (2) Slice the block to obtain φ30*0.4mm composite slices; (3) Select the planetary wheel with the model of φ30*0.4mm ( Figure 3 ), installed on the grinding machine, the composite substrate is installed in a fixed position, and grinding is started to grind the thin sheet to 0.415mm; (4) Select a planetary wheel with a model of φ30*0.4mm, stick a polyurethane polishing pad on the polishing machine, prepare a polishing liquid of a certain concentration with 1μm white corundum powder, and start polishing. The polishing removal amount is 0.02mm; (5) After polishing, place the slice in a sintering furnace, heat it to 400°C, keep it warm for 2 hours, then take it out and clean it; (6) Repeat the process for 3 batches, 300 pieces in each batch, and inspect the products. Thickness exceeding the tolerance and damage are considered unqualified. The unqualified types are calculated separately. The inspection results are shown in Table 1.

[0020] Table 1 Substrate inspection results of Example 1 batch Pass rate Percentage of out-of-tolerance Damage ratio First batch 70% 20% 13% Second batch 72% 15% 16% The third batch 77% 19% 12% Comparative Example 1 Taking the ferrite substrate of φ2*0.4mm and tolerance ±0.005mm of the above-mentioned embodiment 1 as an example, the processing is not carried out by polyurethane wrapping, and the other parameters remain unchanged. The qualified rate after grinding is shown in Table 2.

[0021] Table-2 Inspection of substrate of comparative example 1 batch Pass rate Percentage of out-of-tolerance Damage ratio First batch 30% 16% 58% Second batch 21% 19% 64% The third batch 23% 17% 71% Comparative Example 2 Taking the ferrite substrate of φ2*0.4mm and tolerance ±0.005mm of the above-mentioned embodiment 1 as an example, it is wrapped with epoxy resin, and the ratio of resin to curing agent is 7:3. The other parameters remain unchanged. The qualified rate after grinding is shown in Table 2.

[0022] Table-3 Substrate inspection results of comparative example 2 batch Pass rate Percentage of out-of-tolerance Damage ratio Shedding ratio First batch 51% 25% 13% 11% Second batch 55% 23% 15% 7% The third batch 50% 21% 14% 15% From the comparison of the processing effects of Example 1 and Comparative Example 1, it can be seen that compared with the ferrite substrate not wrapped in polyurethane, the qualified rate of the ferrite substrate wrapped in polyurethane is higher than 60%, and the defect ratio is greatly reduced, and the wrapped polyurethane can be polished, while the unwrapped substrate will be damaged a lot during grinding. In Comparative Example 2 using epoxy resin, due to the high proportion of resin in the epoxy resin formula, the material is soft and has poor viscosity, and it falls off directly during the cleaning process. During the polishing stage, due to the deformation of the resin, the substrate falls off the planetary wheel and is damaged. It can be seen that the processing method of ferrite substrates for ultra-small waveguide devices can grind and polish small substrates for waveguides, and has good qualified rate and operability.

[0023] 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 processing a ferrite substrate for an ultra-small waveguide device, characterized in that: The steps include: (1) Making a composite block: gluing the uncut ferrite material in a columnar state to a chassis and wrapping it around with a thermosetting resin material to obtain a composite block; (2) Cutting the composite block: cutting the composite block obtained in step (1) to obtain a ferrite substrate having four sides wrapped with a thermosetting resin material; (3) Grinding and polishing: Grinding the ferrite substrate obtained in step (2) to achieve the target thickness and surface roughness; (4) Removal of thermosetting resin material: removing the thermosetting resin material around the ferrite substrate to obtain the target ferrite substrate.

2. The method according to claim 1, characterized in that In step (1), the thermosetting resin material is selected from phenolic resin and polyurethane.

3. The method according to claim 1, characterized in that In step (3), the grinding process is performed by using a cast iron grinding wheel and a white corundum grinding fluid.

4. The method according to claim 3, characterized in that The particle size of the white corundum is 10 μm.

5. The method according to claim 1, characterized in that In step (3), after grinding, polishing is also performed.

6. The method according to claim 5, characterized in that The polishing method is to use a polyurethane polishing pad and 1 μm white corundum polishing liquid to perform polishing to achieve a mirror surface state.

7. The method according to claim 1, characterized in that In step (4), the thermosetting resin removal method is to heat the ferrite sheet to 400° C. to burn out the epoxy resin.

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