Polishing method for composite substrate made of materials with different hardness

Abstract

The invention relates to the technical field of precision machining, in particular to a polishing method for composite substrates made of materials with different hardness, which comprises the following steps: S1, thinning the composite substrates by adopting a cast iron millstone and aluminum oxide grinding fluid with the particle size of 7-14 mu m to enable the thickness of the substrates to reach the target thickness; s2, a polyurethane polishing pad is matched with an aluminum oxide polishing solution with the particle size being 2-3 microns to polish the composite substrate; and S3, a polyurethane polishing pad is matched with diamond liquid with the particle size being 1-3 microns to polish the composite substrate. The height difference of the embedded positions of all materials of the polished substrate is lower than 0.1 micron, and the machined substrate is low in surface roughness and good in surface quality. The height difference of the embedded positions of all materials of the polished substrate is lower than 0.1 micron, and the machined substrate is low in surface roughness and good in surface quality.

Description

Technical Field

[0001] This invention relates to the field of precision machining technology, and specifically to a polishing method for composite substrates made of materials with different hardness. Background Technology

[0002] Currently, in the field of microwave devices, multi-material composite substrates have replaced some pure ferrite substrates as the mainstream. To apply microstrip technology to composite substrates, the substrates need to be polished to ensure a surface roughness below 20nm. Furthermore, to ensure circuit continuity, the height difference at the junctions of different materials needs to be below 0.1μm. Ordinary alumina polishing methods struggle to reduce the height difference between multiple composite materials to below 0.3μm. Diamond slurry polishing, on the other hand, has a slow removal rate, is costly, and ordinary diamond slurry is prone to uneven distribution on the polishing pad and poor lubrication of the water film layer, leading to uneven substrate polishing. Summary of the Invention

[0003] The purpose of this invention is to provide a polishing method for composite substrates made of materials with different hardness, thereby solving the technical problems in the prior art where ordinary diamond liquid is easily unevenly distributed on the polishing pad and the water film layer has poor lubrication effect, resulting in uneven substrate polishing.

[0004] This invention discloses a polishing method for composite substrates made of materials with different hardness, comprising the following steps: S1. The composite substrate is thinned by using a cast iron grinding disc and an alumina polishing slurry with a particle size of 7-14μm to achieve the target thickness. S2. Then, the composite substrate is polished using a polyurethane polishing pad and an alumina polishing slurry with a particle size of 2-3μm. S3. Polish the composite substrate using a polyurethane polishing pad and a diamond liquid with a particle size of 1-3μm.

[0005] Furthermore, the composite substrate is a ceramic-ferrite A-ferrite B composite substrate.

[0006] Furthermore, the ceramic in the composite substrate is sleeved outside the ferrite A and ferrite B.

[0007] Furthermore, the ferrite A and ferrite B have different Mohs hardness.

[0008] Furthermore, the polyurethane polishing pad is a polyurethane polishing pad doped with abrasive, and the Shore hardness range of the polyurethane polishing pad is 50-110.

[0009] Furthermore, in step S2, the Shore hardness of the urethane polishing pad is greater than that in step S3.

[0010] Furthermore, in step S2, the urethane polishing pad has a Shore hardness of 90-110.

[0011] Furthermore, in step S3, the urethane polishing pad has a Shore hardness of 70-80.

[0012] Furthermore, in step S1, the cast iron grinding disc is fitted with an alumina grinding slurry with a particle size of 10μm.

[0013] Furthermore, in step S2, the polyurethane polishing pad is combined with an alumina polishing slurry with a particle size of 2μm.

[0014] Furthermore, after polishing is completed in step S2, a secondary polishing with alumina polishing liquid is required.

[0015] Furthermore, the secondary polishing of the alumina polishing slurry involves using a polyurethane polishing pad in conjunction with the alumina polishing slurry with a particle size of less than 2μm.

[0016] Furthermore, in step S3, the polyurethane polishing pad is fitted with 3μm diamond liquid.

[0017] Furthermore, the diamond liquid comprises, by mass ratio, 1%-2.5% diamond powder, 2%-4% sodium carbonate, 4%-8% water.

[0018] Compared with the prior art, the beneficial effects of the present invention are: 1. After polishing, the height difference between the materials at the joint of the substrate is less than 0.1 μm, and the surface roughness of the substrate is low and the surface quality is good. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the substrate structure used in an embodiment of the present invention.

[0021] In the above figures, the meanings of each mark are as follows: 1 - ceramic with a Mohs hardness of 8.5, 2 - ferrite A with a Mohs hardness of 6.5, and 3 - ferrite B with a Mohs hardness of 7.5. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0023] Example 1 This embodiment discloses a polishing method for composite substrates made of materials with different hardness, including the following steps: Taking the processing of the 20*20-6*6-2*2mm ceramic-ferrite-ferrite composite substrate in this embodiment as an example, the substrate structure is as follows: Figure 1 As shown.

[0024] 1. First, install a cast iron grinding disc on a double-sided grinding machine, and use an alumina grinding slurry with a particle size of 10μm and a concentration of 25% to grind the composite substrate. Grind the substrate thickness from 0.54mm to 0.43mm.

[0025] 2. Place a polyurethane polishing pad with a Shore hardness of 90 on a double-sided polishing machine, prepare an alumina polishing liquid with a thickness of 2μm and a certain concentration, and start polishing until the thickness is 0.41mm.

[0026] 3. Apply a polyurethane polishing pad with a Shore hardness of 80 to the double-sided polishing machine. Prepare a 3μm diamond liquid by mixing 1.5% diamond powder, 2% sodium carbonate, 4% polyethylene glycol and water. Begin polishing until the thickness reaches 0.4mm.

[0027] 4. The height difference and surface roughness of the mating area were tested using a step tester and a probe roughness tester. The test results are shown in Table 1-1 and Table 1-2.

[0028] Table 1-1 Height Difference of Composite Substrate Interlocking Area

[0029] Table 1-2 Roughness of various parts of the composite substrate

[0030] Comparative Example 1 Taking the processing of the 20*20-6*6-2*2mm ceramic-ferrite-ferrite composite substrate in this embodiment as an example, the working method is as follows: 1. First, install a cast iron grinding disc on a double-sided grinding machine, and use an alumina grinding slurry with a particle size of 10μm and a concentration of 25% to grind the composite substrate. Grind the substrate thickness from 0.54mm to 0.43mm.

[0031] 2. Attach a polyurethane polishing pad with a Shore hardness of 90 to the double-sided polishing machine, prepare an alumina polishing liquid with a thickness of 2μm and a certain concentration, install a stainless steel planetary wheel with a thickness of 0.40mm on the equipment and start polishing until the thickness is 0.40mm.

[0032] 3. The height difference and surface roughness of the mating area were tested using a step tester and a probe-type roughness tester. The test results are shown in Tables 2-1 and 2-2.

[0033] Table 2-1 Height Difference of Composite Substrate Interlocking Area

[0034] Table 2-2 Roughness of various parts of the composite substrate

[0035] A comparison of the processing effects in the examples and comparative examples shows that, compared with the conventional processing method, the height difference between the interlocking regions of the materials in the new processing method is reduced from about 0.4 μm to below 0.1 μm. After polishing, the surface roughness of the ceramic is reduced to 17 nm, ferrite A to 11 nm, and ferrite B to 15 nm. This demonstrates that the polishing method for composite substrates of materials with different hardness can effectively reduce the thickness difference in composite material polishing and improve the polishing effect to a certain extent. Comparative Example 2 Taking the processing of the 20*20-6*6-2*2mm ceramic-ferrite-ferrite composite substrate in this embodiment as an example, the substrate structure is as follows: Figure 1 As shown.

[0036] 1. First, install a cast iron grinding disc on a double-sided grinding machine, and use an 8μm particle size and 25% concentration alumina grinding slurry to grind the composite substrate. Grind the substrate thickness from 0.54mm to 0.41mm.

[0037] 2. Apply a polyurethane polishing pad with a Shore hardness of 80 to the double-sided polishing machine. Prepare a 3μm diamond liquid with 1.5% diamond powder, 4% polyethylene glycol and water, and start polishing until the thickness is 0.4mm.

[0038] 3. The height difference and surface roughness of the mating area were tested using a step tester and a probe-type roughness tester. The test results are shown in Tables 3-1 and 3-2.

[0039] Table 3-1 Height Difference of Composite Substrate Interlocking Area

[0040] Table 3-2 Roughness of various parts of the composite substrate

[0041] A comparison of the processing effects of the examples and the comparative examples shows that, compared with the method of polishing with diamond liquid alone, the height difference between the interlocking areas of the materials in the new processing method is small and stable below 0.1μm. The overall surface roughness of the substrate changes little after polishing, while the roughness difference after polishing with diamond liquid alone is 5-10nm.

[0042] Comparative Example 3 This embodiment discloses a polishing method for composite substrates made of materials with different hardness, including the following steps: Taking the processing of the 20*20-6*6-2*2mm ceramic-ferrite-ferrite composite substrate in this embodiment as an example, the substrate structure is as follows: Figure 1 As shown.

[0043] 1. First, install a cast iron grinding disc on a double-sided grinding machine, and use an alumina grinding slurry with a particle size of 10μm and a concentration of 25% to grind the composite substrate. Grind the substrate thickness from 0.54mm to 0.43mm.

[0044] 2. Place a polyurethane polishing pad with a Shore hardness of 90 on a double-sided polishing machine, prepare an alumina polishing liquid with a thickness of 2μm and a certain concentration, and start polishing until the thickness is 0.41mm.

[0045] 3. Apply a polyurethane polishing pad with a Shore hardness of 80 to the double-sided polishing machine, prepare a 3μm diamond liquid with 1.5% diamond powder and water, and start polishing until the thickness is 0.4mm.

[0046] 4. The height difference and surface roughness of the mating area were tested using a step tester and a probe-type roughness tester. The test results are shown in Tables 4-1 and 4-2.

[0047] Table 4-1 Height Difference of Composite Substrate Interlocking Area

[0048] Table 4-2 Roughness of various parts of the composite substrate

[0049] A comparison of the processing effects of the examples and the comparative examples shows that, using only water as a solvent, the overall surface roughness after diamond liquid polishing is relatively large, and the height difference also varies significantly. With only water as a solvent, the diamond powder is unevenly dispersed on the disk surface, and the water film layer provides poor support, causing the substrate to be adsorbed by the polishing pad, resulting in an uneven grinding process and a tendency for small defects to occur.

[0050] The above are the embodiments listed in this example. However, this example is not limited to the optional embodiments described above. Those skilled in the art can arbitrarily combine the above methods to obtain other various embodiments. Anyone can derive other various forms of embodiments based on the inspiration of this example. The above specific embodiments should not be construed as limiting the scope of protection of this example. The scope of protection of this example should be determined by the claims, and the specification can be used to interpret the claims.

Claims

1. A polishing method for composite substrates made of materials with different hardness, characterized in that: Includes the following steps: S1. The composite substrate is thinned by using a cast iron grinding disc and an alumina polishing slurry with a particle size of 7-14μm to achieve the target thickness. S2. Then, the composite substrate is polished using a polyurethane polishing pad and an alumina polishing slurry with a particle size of 2-3μm. S3. Polish the composite substrate using a polyurethane polishing pad and a diamond liquid with a particle size of 1-3μm.

2. The polishing method for a composite substrate of materials with different hardness according to claim 1, characterized in that: The composite substrate is a ceramic-ferrite A-ferrite B composite substrate.

3. The polishing method for a composite substrate of materials with different hardness according to claim 2, characterized in that: In the composite substrate, the ceramic is sleeved outside the ferrite A and ferrite B; And / or the ferrite A and ferrite B have different Mohs hardness.

4. The polishing method for a composite substrate of materials with different hardness according to claim 1, characterized in that: The polyurethane polishing pad is a polyurethane polishing pad doped with abrasive, and the Shore hardness range of the polyurethane polishing pad is 50-100.

5. The polishing method for a composite substrate of materials with different hardness according to claim 4, characterized in that: In step S2, the Shore hardness of the urethane polishing pad is greater than that in step S3.

6. The polishing method for a composite substrate of materials with different hardness according to claim 1, characterized in that: In step S1, the cast iron grinding disc is fitted with an alumina grinding slurry with a particle size of 10μm.

7. The polishing method for a composite substrate of materials with different hardness according to claim 1, characterized in that: In step S2, the polyurethane polishing pad is combined with an alumina polishing slurry with a particle size of 2μm.

8. The polishing method for a composite substrate of materials with different hardness according to claim 1, characterized in that: After polishing is completed in step S2, a second polishing with alumina polishing liquid is required.

9. The polishing method for a composite substrate of materials with different hardness according to claim 8, characterized in that: The secondary polishing of the alumina polishing slurry involves using a polyurethane polishing pad in conjunction with the alumina polishing slurry with a particle size of less than 2μm.

10. The polishing method for a composite substrate of materials with different hardness according to claim 1, characterized in that: The diamond solution comprises, by mass ratio, 1%-2.5% diamond powder, 2%-4% sodium carbonate, 4%-8% water.

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