Method for binding an alkali metal planar target and an alkali metal target assembly

Abstract

The application belongs to the technical field of alkali metal plane target material binding, and discloses an alkali metal plane target material binding method. The method is characterized in that: through the use of conductive glue for adhesion between the pretreated alkali metal target blank and the back plate, and the conductive medium is doped in the conductive glue, the adhesion is good, and the resistance between the alkali metal target and the back plate is reduced. In addition, the application also discloses a conductive glue, in which graphite is added instead of traditional carbon black to improve the conductivity of the target material interface. In addition, the application also provides a lithium target assembly prepared by the above-mentioned conductive glue and alkali metal plane target material binding method.

Description

Technical Field

[0001] This invention relates to the field of alkali metal planar target bonding technology, specifically to an alkali metal planar target bonding method and an alkali metal target assembly. Background Technology

[0002] In recent years, with the vigorous development of the electronic information and high-tech industries, the demand for new thin film materials has been increasing, and the application of thin film materials directly affects the development process of information technology in my country.

[0003] Sputtering targets are the raw materials for preparing thin films, and their overall quality significantly impacts film performance. In practical applications, sputtering targets need to be combined with metal alloy backing plates to form target assemblies for sputtering. Poor bonding between the target and backing plate can lead to target deformation, cracking, and detachment during sputtering, affecting not only the performance of the sputtered film but also, in severe cases, damaging the sputtering equipment.

[0004] Chinese patent application 201910015776.3 discloses a method for manufacturing a lithium target assembly. The method involves providing a lithium target blank having a first main surface and a first back surface opposite to the first main surface; providing a backplate having a second main surface and a second back surface opposite to the second main surface; performing lithium plating on the second main surface of the backplate to form a lithium plating layer; placing and bonding the lithium plating layer on the first main surface of the lithium target blank and the second main surface of the backplate opposite to each other to form an initial assembly; and applying pressure to the initial assembly in a vacuum environment to bond the lithium target blank to the lithium plating layer, thereby completing the bonding of the lithium target blank and the backplate and forming a lithium target assembly.

[0005] The bonding technology used in this scheme is diffusion welding, which utilizes the interaction of lithium atoms between the lithium target and the lithium plating layer under the influence of temperature and pressure to form a new diffusion layer, thereby achieving welding bonding. Among existing bonding technologies, there are relatively few bonding technologies for lithium targets.

[0006] The problem this solution aims to solve is: how to propose a cost-effective and efficient bonding method for alkali metal planar targets. Summary of the Invention

[0007] The purpose of this invention is to propose a bonding method for alkali metal planar targets, which improves the bonding force between the target and the epoxy resin and reduces the resistance between them by using the epoxy resin and conductive medium in the conductive adhesive.

[0008] To achieve the above objectives, this application discloses a method for bonding alkali metal planar targets, comprising the following steps:

[0009] Step 1: Dry the alkali metal planar target and backing plate;

[0010] Step 2: Apply conductive adhesive to the bonding surface of the alkali metal planar target and the bonding surface of the backplate, respectively;

[0011] Step 3: Place the bonding surface of the alkali metal planar target coated with conductive adhesive onto the bonding surface of the back plate coated with conductive adhesive, let it stand, press, and cure to complete the bonding of the alkali metal planar target;

[0012] The conductive adhesive is composed of 20-50 parts epoxy resin, 20-50 parts copper powder, 5-20 parts graphite, 1-10 parts silicon dioxide, 1-10 parts aluminum oxide, and 1-10 parts calcium carbonate by weight.

[0013] Preferably, the alkali metal planar target is a lithium target.

[0014] Preferably, in step 2, two parallel copper wires cured with conductive adhesive are placed on the backplate bonding surface, and the diameter of the copper wires is 0.1 to 0.5 mm.

[0015] Preferably, the operation of coating the bonding surface of the alkali metal planar target with conductive adhesive is as follows: uniformly apply conductive adhesive to the bonding surface of the alkali metal planar target, let it stand, scrape off the residual conductive adhesive on the surface with a silicone pad, and repeat the above operation twice to complete the coating of conductive adhesive.

[0016] The thickness of the conductive adhesive on the bonding surface of the alkali metal planar target is 0.1–0.5 mm.

[0017] Preferably, the settling time in step 3 is 3 to 10 minutes.

[0018] Preferably, the curing temperature in step 3 is 60–100°C, and the curing time is 2–4 hours.

[0019] Preferably, xylene is also added to the conductive adhesive, and the xylene accounts for 25% to 75% of the total mass of the conductive adhesive.

[0020] Preferably, the epoxy resin is selected from at least one of bisphenol A type epoxy resin, bisphenol F type epoxy resin, and polyphenol glycidyl ether.

[0021] Preferably, the alkali metal planar target bonding method needs to be carried out in an environment with a water oxygen value of less than 0.1 ppm.

[0022] In addition, an alkali metal target assembly is disclosed, wherein the alkali metal target assembly is obtained by binding an alkali metal planar target to a back plate using any of the alkali metal planar target binding methods described above.

[0023] The beneficial effects of this invention are:

[0024] This invention provides a bonding method for alkali metal planar targets. By using epoxy resin and conductive medium in the conductive adhesive, the bonding force between the target and the target is improved and the resistance between them is reduced. In addition, graphite is added to the conductive adhesive to improve the conductivity of the target interface. This bonding process is not only simple in terms of equipment and preparation process, and the yield can reach more than 90%, but it also does not cause alkali metals to undergo violent chemical reactions and has good stability. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of conductivity site testing. A, B, and C are red pen test points, and D is a black pen test point. Detailed Implementation

[0026] In the description of this invention, it should be noted that unless specific conditions are specified in the examples, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0027] Examples 1-5

[0028] A conductive adhesive, the composition of which is shown in Table 1:

[0029] Table 1

[0030]

[0031]

[0032] The epoxy resins described in Examples 1-5 are bisphenol A type epoxy resins.

[0033] The conductive adhesive is prepared by mixing copper powder, graphite, silicon dioxide, aluminum oxide, and calcium carbonate in the proportions specified in the above formula, adding them to bisphenol A epoxy resin, and then homogenizing them at 12-30 r / min for 2 hours in a mixer to obtain the conductive adhesive.

[0034] Application Example 1

[0035] Step 1: Dry the lithium target and backplate at 50°C for 2 hours;

[0036] Step 2: By applying conductive adhesive to the lithium target bonding surface, letting it stand, scraping off the residual conductive adhesive on the surface with a silicone sheet, and repeating the above operation twice, a lithium target bonding surface coated with 0.3mm of conductive adhesive is obtained, and a backplate bonding surface coated with conductive adhesive of the same height as the 0.3mm diameter copper wire is applied to the backplate bonding surface.

[0037] Step 3: Place the bonding surface of the alkali metal planar target coated with conductive adhesive onto the bonding surface of the back plate coated with conductive adhesive, let stand for 6 minutes, press, and cure at 80°C for 3 hours to complete the bonding of the alkali metal planar target;

[0038] The conductive adhesive used was the conductive adhesive prepared in Example 1, and xylene accounted for 33% of the total mass of the conductive adhesive.

[0039] Application Example 2

[0040] Step 1: Dry the lithium target and backplate at 50°C for 2 hours;

[0041] Step 2: By applying conductive adhesive to the lithium target bonding surface, letting it stand, scraping off the residual conductive adhesive on the surface with a silicone sheet, and repeating the above operation twice, a lithium target bonding surface coated with 0.1mm of conductive adhesive is obtained, and a backplate bonding surface coated with conductive adhesive of the same height as the 0.1mm diameter copper wire is applied to the backplate bonding surface.

[0042] Step 3: Place the bonding surface of the alkali metal planar target coated with conductive adhesive onto the bonding surface of the back plate coated with conductive adhesive, let stand for 6 minutes, press, and cure at 80°C for 3 hours to complete the bonding of the alkali metal planar target;

[0043] The conductive adhesive used was the conductive adhesive prepared in Example 1, and xylene accounted for 33% of the total mass of the conductive adhesive.

[0044] Application Example 3

[0045] Step 1: Dry the lithium target and backplate at 50°C for 2 hours, and place them in an environment with an oxygen content below 0.1 ppm for later use;

[0046] Step 2: Apply conductive adhesive to the lithium target bonding surface, let it stand, scrape off the residual conductive adhesive on the surface with a silicone sheet, and repeat the above operation twice to obtain a lithium target bonding surface coated with 0.5mm of conductive adhesive and a backplate bonding surface coated with conductive adhesive of the same height as the 0.5mm diameter copper wire.

[0047] Step 3: Place the bonding surface of the alkali metal planar target coated with conductive adhesive onto the bonding surface of the back plate coated with conductive adhesive, let stand for 6 minutes, press, and cure at 80°C for 3 hours to complete the bonding of the alkali metal planar target;

[0048] The conductive adhesive used was the conductive adhesive prepared in Example 1, and xylene accounted for 33% of the total mass of the conductive adhesive.

[0049] Application Example 4

[0050] It is basically the same as Application Example 1, except that the conductive adhesive is the conductive adhesive prepared in Example 2.

[0051] Application Example 5

[0052] It is basically the same as Application Example 1, except that the conductive adhesive is the conductive adhesive prepared in Example 3.

[0053] Application Example 6

[0054] It is basically the same as Application Example 1, except that the xylene is 25% of the total mass of the conductive adhesive.

[0055] Application Example 7

[0056] It is basically the same as Application Example 1, except that the xylene is 75% of the total mass of the conductive adhesive.

[0057] Application Example 8

[0058] It is basically the same as Application Example 1, except that the conductive adhesive is the conductive adhesive prepared in Comparative Example 1.

[0059] Application Example 9

[0060] It is basically the same as Application Example 1, except that the conductive adhesive is the conductive adhesive prepared in Comparative Example 2.

[0061] Application Example 10

[0062] It is basically the same as Application Example 1, except that carbon black is used instead of graphite in the conductive adhesive.

[0063] Application Example 11

[0064] It is basically the same as Application Example 1, except that the water oxygen value of the bound operating environment is 0.15 ppm.

[0065] Performance testing:

[0066] Adhesion strength: Tested according to GB / T 39163-2020 Test method for bonding strength between target and backing plate;

[0067] Resistance between the target and the backing plate: After curing, the target is removed and polished with sandpaper and wiped with a lint-free cloth. After polishing and wiping, the resistance of the target is tested. Figure 1 As shown.

[0068] The test results are shown in Table 2:

[0069] Table 2

[0070]

[0071]

[0072] Results analysis:

[0073] 1. As can be seen from Application Examples 1-3, the copper wire fixed on the backplate bonding surface is used to determine the thickness of the conductive adhesive between the backplate bonding surface and the alkali metal planar target bonding surface. Therefore, in Application Example 1, the thickness of the conductive adhesive between the backplate bonding surface and the alkali metal planar target bonding surface is 0.3 mm.

[0074] In application example 2, the thickness of the conductive adhesive between the backplate bonding surface and the alkali metal planar target bonding surface is 0.1 mm;

[0075] In application example 3, the thickness of the conductive adhesive between the backplate bonding surface and the alkali metal planar target bonding surface is 0.5 mm, and according to the data in Table 3:

[0076] Table 3

[0077] resistance Adhesion strength Application Example 1 0.10Ω 5.1MPa Application Example 2 0.09Ω 4.6MPa Application Example 3 0.20Ω 5.2MPa

[0078] The experimental data shows that when the thickness of the conductive adhesive is reduced from 0.3mm to 0.1mm, the adhesive curing thickness is too low due to the reduced thickness, resulting in poor bonding ability and a decrease in adhesion strength of 0.5MPa. As is well known, resistance is proportional to length. When the thickness of the conductive adhesive is increased from 0.3mm to 0.5mm, the adhesion strength is not significantly improved, but the resistivity increases by 0.1Ω due to the increased thickness of the conductive adhesive.

[0079] 2. As can be seen from Application Examples 1 and 4-5, the conductive adhesives used in these three examples correspond to those prepared in Examples 1 and 2-3, respectively. After bonding is completed, the data of the bonding target materials are shown in Table 4:

[0080] Table 4

[0081]

[0082]

[0083] The data shows that as the content of graphite and copper powder in the conductive adhesive increases, its resistivity gradually decreases; and as the mass fraction of epoxy resin in the conductive adhesive increases, the adhesion will also be enhanced since the total thickness of the conductive adhesive remains unchanged.

[0084] 3. As can be seen from Application Example 1 and Application Examples 6-7, in Application Example 1, xylene accounts for 33% of the total mass of the conductive adhesive;

[0085] In application example 6, xylene accounts for 25% of the total mass of the conductive adhesive;

[0086] In Application Example 7, xylene constitutes 75% of the total mass of the conductive adhesive. As shown in Table 5, the experimental data indicates:

[0087] Table 5

[0088] resistance Adhesion strength Application Example 1 0.10Ω 5.1MPa Application Example 6 0.20Ω 4.5MPa Application Example 7 0.30Ω 5.2MPa

[0089] The experimental data shows that when there is too much xylene used for dilution in the conductive adhesive, the conductive adhesive is over-diluted, which leads to a relative dilution of its effective components. As a result, the resistance and adhesion strength of the target material it bonds with will deteriorate. On the other hand, when there is too little xylene used for dilution in the conductive adhesive, although its adhesion strength is better, its poor fluidity prevents the graphite and copper powder from spreading evenly, resulting in different resistances at different sites on the target material.

[0090] 4. As can be seen from Application Examples 1 and 8-9, compared with Application Example 1, no graphite was added to the conductive adhesive in Application Example 8;

[0091] In Application Example 9, no copper powder was added to the conductive adhesive. The experimental data are shown in Table 6.

[0092] Table 6

[0093]

[0094]

[0095] Experimental data shows that the lack of graphite or copper powder in conductive adhesives leads to a significant increase in the resistance between the target material and the backing plate. Therefore, graphite and copper powder are indispensable components.

[0096] Furthermore, compared to Application Example 1 and Application Example 10, in Application Example 10, carbon black, which is also a carbon-based material, was used to replace graphite in the conductive adhesive. Compared to the conductive adhesive in Application Example 8, which did not contain graphite, carbon black can also reduce the resistance between the target material and the backing plate, but the reduction is much smaller than that of graphite.

[0097] 5. By comparing Application Example 1 with Application Example 11, in Application Example 11, the bonding of the alkali metal planar target was carried out in an environment with a water oxygen value of 0.15 ppm. Because the moisture content in the environment is high, the alkali metal target will react with water to produce gas. On the one hand, this causes the target surface to be irregular, and on the other hand, it also produces gas, resulting in voids inside the conductive adhesive, which leads to an increase in the resistance between the target and the backing plate.

[0098] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for bonding alkali metal planar targets, characterized in that, Includes the following steps: Step 1: Dry the alkali metal planar target and backing plate; Step 2: Apply conductive adhesive to the bonding surface of the alkali metal planar target and the bonding surface of the backplate, respectively; Step 3: Place the bonding surface of the alkali metal planar target coated with conductive adhesive onto the bonding surface of the back plate coated with conductive adhesive, let it stand, press, and cure to complete the bonding of the alkali metal planar target; The conductive adhesive is composed of 35-50 parts epoxy resin, 35-50 parts copper powder, 12-20 parts graphite, 6-10 parts silicon dioxide, 6-10 parts aluminum oxide, and 6-10 parts calcium carbonate by weight. The conductive adhesive is diluted with xylene, and the xylene accounts for 33% of the total mass of the conductive adhesive. The method for bonding alkali metal planar targets must be carried out in an environment where the oxygen content of the water is below 0.1 ppm; The thickness of the conductive adhesive on the bonding surface of the alkali metal planar target and the bonding surface of the back plate is 0.3 mm.

2. The alkali metal planar target bonding method according to claim 1, characterized in that, The alkali metal planar target is a lithium target.

3. The method for bonding alkali metal planar targets according to claim 1, characterized in that, In step 2, two parallel copper wires, each 0.3 mm in diameter, are placed on the backplate bonding surface.

4. The method for bonding alkali metal planar targets according to claim 1, characterized in that, The operation of coating the bonding surface of the alkali metal planar target with conductive adhesive is as follows: apply conductive adhesive to the bonding surface of the alkali metal planar target, let it stand, scrape off the residual conductive adhesive on the surface with a silicone pad, and repeat the above operation twice to complete the coating of conductive adhesive.

5. The method for bonding alkali metal planar targets according to claim 1, characterized in that, The settling time in step 3 is 3 to 10 minutes.

6. The method for bonding alkali metal planar targets according to claim 1, characterized in that, In step 3, the curing temperature is 60–100℃ and the curing time is 2–4 hours.

7. The method for bonding alkali metal planar targets according to claim 1, characterized in that, The epoxy resin is selected from at least one of bisphenol A type epoxy resin and bisphenol F type epoxy resin.

8. An alkali metal target assembly, characterized in that, The alkali metal target assembly is obtained by binding the alkali metal planar target to the back plate using the alkali metal planar target binding method according to any one of claims 1-7.

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