A method for correcting deformation of a planar target backing plate

Abstract

The application discloses a kind of plane target material back plate deformation correction method, belong to target material manufacturing technical field, step one, the copper back plate 2 to be bound is fixed on movable metal plate, heating, temperature is raised to 170-190 DEG C;Step two, as the soldering material indium is evenly plated on the copper back plate of step one, then ITO target material is brazed on the copper back plate to obtain target material back plate combination;Step three, stop heating, target material back plate combination natural cooling, with target material back plate combination metal plate is transferred to the ultrasonic water tank with same temperature with target material, heat preservation and ultrasonic;Step four, control water in ultrasonic to room temperature, with target material back plate combination metal plate is transferred to stand, remove metal plate, measure target material flatness.The whole flatness of single block target material 1m above treated by the method can be controlled in the range of 0-2mm, which greatly reduces the risk of target material rupture in subsequent use.

Description

Technical Field

[0001] This invention belongs to the field of target manufacturing technology, and specifically relates to a method for correcting deformation of the back plate of a planar target. Background Technology

[0002] Planar targets such as ITO and AZO are commonly used in display screens, solar cells, and special glass. They are usually bonded to a copper backplate and the material is uniformly deposited onto the substrate by means of magnetron sputtering. In order to ensure the uniformity of the coating during magnetron sputtering, the shortest distance between the target surface and the substrate should be consistent. This places high demands on the flatness of the target-backplate composite. The flatness after the target is bonded is directly related to the quality of the magnetron sputtering film.

[0003] Conventional target bonding technology involves heating the backplate and indium to over 170°C and then brazing the target onto the copper backplate using indium. This method is acceptable for bonding small-sized planar targets. However, in recent years, with the increasing market demand for large-sized display devices and the continuous improvement of film quality requirements, the size of planar targets has also increased. Using this method to bond large-sized planar targets with a single target length exceeding 1 meter will lead to excessive bonding deformation.

[0004] Because the target material has a smaller coefficient of thermal expansion than copper, during the cooling process of the target material, as indium cools and solidifies, it is welded to the copper back plate. The side of the copper back plate that is bonded to the target material has a smaller shrinkage due to the limitation of the target material, while the side that is not welded to the target material has a larger shrinkage. Therefore, the two sides of the copper back plate will have different shrinkage rates, which will manifest as the back plate bending and bulging towards the target material. The problem becomes more and more obvious as the length of the target material increases. Therefore, an improved method is often used to bind planar targets with a single target material length of more than 1 meter.

[0005] The commonly used improvement method is to press heavy objects onto the target during the bonding and cooling process to suppress deformation. This bonding method usually generates significant stress inside the target and backing plate, which increases the risk of target breakage as the target thins during subsequent magnetron sputtering. In addition, it is difficult to guarantee flatness after bonding, and usually leaves a 2-3mm bulge deformation. Since the relatively fragile planar target is bonded to the copper backing plate and indium layer after bonding, it cannot be subjected to severe impact or vibration. Therefore, general stress relief methods such as mechanical vibration and shot peening are not suitable for target bonding. Summary of the Invention

[0006] To address the bonding problem of large-size planar targets, a method is proposed to use ultrasonic waves to relieve stress on the bonded target and backing plate after the target is bonded.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0008] A method for correcting deformation of a planar target backing plate includes the following steps:

[0009] Step 1: Fix the copper backplate 2 to be bound onto the movable metal plate and heat it to 170-190℃;

[0010] Step 2: Indium, which is used as a welding material, is uniformly coated onto the copper back plate in Step 1, and then the ITO target is brazed onto the copper back plate to obtain the target back plate assembly.

[0011] Step 3: Stop heating and allow the target backplate assembly to cool down naturally. Transfer the metal plate with the target backplate assembly to an ultrasonic water bath containing the same temperature as the target material, keep it warm and then perform ultrasonic treatment.

[0012] Step 4: Control the water in the ultrasonic wave to cool down to room temperature, transfer the metal plate with the target backplate assembly out and let it stand, remove the metal plate, and measure the flatness of the target.

[0013] A further improvement to the technical solution of the present invention is that: in step three, the ultrasonic water tank performs ultrasonic treatment on the metal plate with the target backplate assembly with a power of 5-10kw and an ultrasonic frequency of 30-50kHz.

[0014] A further improvement to the technical solution of the present invention is that the heat preservation temperature in step three is 80-90℃ and the heat preservation time is 2-4h.

[0015] A further improvement of the technical solution of the present invention is that the cooling rate of the water in the water tank in step four is 5-25℃ / h.

[0016] A further improvement of the technical solution of the present invention is that the surface of the metal plate is flat, including stainless steel plate.

[0017] A further improvement to the technical solution of the present invention is that the ITO target material is cut to a suitable size and the side that needs to be welded is plated with a layer of indium metal.

[0018] A further improvement of the technical solution of the present invention is that: two rows of fixing devices are provided on both sides of the metal plate, and the fixing devices include bolt pressure plates, which are fixed to the metal plate by bolts.

[0019] The technological advancements achieved by this invention due to the adoption of the above technical solutions are as follows:

[0020] Since indium has a melting point of 156°C, when the temperature drops below 156°C, indium changes from a liquid to a solid state. The surface contraction of the copper backing plate is restricted, and stress is generated in the copper backing plate, the indium layer, and the target material. This stress gradually increases as the temperature decreases. When the target material is in a liquid medium, ultrasound waves can be uniformly transmitted to all parts of the target material through the liquid. When these parts of the target material are subjected to ultrasonic vibrations, the vibrations can be transmitted to the indium layer through the target material or the copper plate. The ultrasound waves introduce alternating stress onto the indium layer. This alternating stress is superimposed on the residual stress in the indium layer. When the area of ​​most severe stress concentration exceeds the yield limit of indium, plastic deformation occurs. This plastic deformation reduces and homogenizes the residual stress at that location. Furthermore, when the metal temperature is more than 0.4 times its absolute melting point, the metal material will creep under loads below the yield limit, and high temperatures promote creep. Since indium's melting point is only 156°C, and water is used as the ultrasonic propagation medium, ultrasonic treatment at 80-90°C is chosen to promote indium creep and release the stress generated when the temperature drops from 156°C to 80-90°C. After the heat preservation is completed, the water tank is cooled to room temperature at a slow cooling rate. During the cooling process, the target material is treated with ultrasound. The stress in the indium layer is released slowly and evenly through slow cooling and ultrasound treatment.

[0021] The flatness of a single target material longer than 1m after processing using this method can be controlled within the range of 0-2mm. Furthermore, since the flatness is achieved by releasing stress after bonding, the risk of target material breakage is greatly reduced during subsequent use. Attached Figure Description

[0022] Figure 1 This is a structural diagram of the bonding structure of the metal plate and the target backplate assembly of the present invention;

[0023] Among them, 1. ITO target material, 2. copper back plate, 3. metal plate, and 4. bolt pressure plate. Detailed Implementation

[0024] The present invention will be further described in detail below with reference to embodiments:

[0025] A method for correcting deformation of a planar target backing plate, characterized by comprising the following steps:

[0026] Step 1: Fix the copper backplate 2 to be bound onto the movable metal plate 3, and heat it to 170-190℃.

[0027] Step 2: Indium is uniformly coated onto the copper back plate 2 from Step 1 as a welding material, and then ITO target 1 is brazed onto the copper back plate to obtain the target back plate assembly.

[0028] Step 3: Stop heating and allow the target backplate assembly to cool down naturally. Transfer the metal plate with the target backplate assembly to an ultrasonic water bath containing the same temperature as the target material, keep it warm and then perform ultrasonic treatment.

[0029] Step 4: Control the water in the ultrasonic wave to cool down to room temperature, transfer the metal plate with the target backplate assembly out and let it stand, remove metal plate 3, and measure the flatness of the target.

[0030] Example 1

[0031] Under an operating environment of 25℃, the 3000mm copper backplate 2 to be bound is fixed to the movable metal plate 3 (i.e., the stainless steel plate platform) using bolts and bolt clamping plate 4. The stainless steel plate platform is placed on the heating platform, and the target material is heated to 190℃. Indium, used as a welding material, is uniformly coated onto the copper backplate 2. Then, two pre-treated 1325*210*8mm ITO planar targets are brazed onto the copper backplate. After naturally cooling to 90℃, the stainless steel plate is lifted using lifting slings and transferred to an ultrasonic water tank containing 90℃ water. The ultrasonic switch of the water tank is turned on, the ultrasonic power is adjusted to 10kW, and the temperature is maintained for 3 hours. Then, the water temperature is lowered to 25℃ at a cooling rate of 10℃ / h. The ultrasonic is turned off, and the stainless steel plate is lifted out and left to stand for 12 hours. After that, the clamps are loosened, and the bound target material backplate composite is placed on a flat platform. The degree of deformation of the target material is measured, and the maximum deformation at the upper bulge is measured to be 0.6mm using a feeler gauge.

[0032] Example 2

[0033] Under an operating environment of 25℃, the 3000mm copper backplate 2 to be bound was bolted to a movable stainless steel plate platform (metal plate 3). The stainless steel plate platform was placed on a heating platform, and the target material was heated to 190℃. Indium, used as a welding material, was uniformly coated onto the copper backplate. Then, two pre-treated 1325*210*8mm ITO planar targets 1 were brazed onto the copper backplate 2. After naturally cooling to 90℃, the stainless steel plate was lifted using a hoisting sling and transferred to an ultrasonic water tank containing 90℃ water. The ultrasonic switch of the water tank was turned on, the ultrasonic power was adjusted to 5kw, and the temperature was maintained for 3 hours. Then, the water temperature was lowered to 25℃ at a cooling rate of 10℃ / h. The ultrasonic was turned off, and the stainless steel plate was lifted out and left to stand for 12 hours. After that, the clamps were loosened, and the bound target material and backplate composite was placed on a flat platform. The degree of deformation of the target material was measured, and the maximum deformation at the upper bulge was measured to be 1.1mm using a feeler gauge.

[0034] Comparative Example 1

[0035] Under an operating environment of 25℃, the 3000mm copper backplate to be bound was bolted to a movable stainless steel plate platform. The stainless steel plate platform was placed on a heating platform, and the target material was heated to 190℃. Indium, used as a welding material, was uniformly coated onto the copper backplate. Then, two pre-treated 1325*210*8 ITO planar targets were brazed onto the copper backplate. After adjusting the stainless steel plate to a flat platform, 26 iron blocks, totaling 260kg, were evenly placed on the upper surface of the planar target. The clamps on the stainless steel plate were loosened. At this point, it can be seen that the lower surface of the copper backplate is tightly attached to the upper surface of the stainless steel plate without deformation. After standing for 48 hours, the iron blocks were removed, and the bound target material backplate composite was placed on a flat platform. The degree of deformation of the target material was measured, and the maximum deformation at the upper bulge was measured to be 2.5mm using a feeler gauge.

[0036] By comparing the deformation data of Examples 1 and 2 and Comparative Example 1, it can be seen that using ultrasound to process the bonded target backplate composite can quickly and effectively reduce the deformation caused by bonding and improve the quality of bonding large-size planar targets.

Claims

1. A method for correcting deformation of a planar target backing plate, characterized in that... Includes the following steps: Step 1: Fix the copper backplate (2) to be bound onto the movable metal plate (3), and heat it to 170-190℃; Step 2: Indium is uniformly coated onto the copper back plate (2) of Step 1 as a welding material, and then the ITO target (1) is brazed onto the copper back plate to obtain the target back plate assembly. Step 3: Stop heating and allow the target backplate assembly to cool down naturally. Transfer the metal plate with the target backplate assembly to an ultrasonic water bath containing the same temperature as the target material, keep it warm and then perform ultrasonic treatment. The holding temperature is 80-90℃ and the holding time is 2-4 hours. Step 4: Control the water in the ultrasonic wave to cool down to room temperature, transfer the metal plate with the target backplate assembly out and let it stand, remove the metal plate (3), and measure the flatness of the target; the cooling rate is 5-25℃ / h.

2. The method for correcting deformation of a planar target backplate according to claim 1, characterized in that: In step three, the ultrasonic water tank performs ultrasonic treatment on the metal plate with the target backplate assembly with a power of 5-10kw and an ultrasonic frequency of 30-50kHz.

3. The method for correcting deformation of a planar target backplate according to claim 1, characterized in that: The metal plate has a flat surface, including stainless steel plates.

4. The method for correcting deformation of a planar target backplate according to claim 1, characterized in that: The ITO target material is cut to the appropriate size, and the side that needs to be welded is plated with a layer of indium metal.

5. The method for correcting deformation of a planar target backplate according to claim 1, characterized in that: Two rows of fixing devices are provided on both sides of the metal plate (3). The fixing devices include bolt pressure plates (4) which are fixed to the metal plate by bolts.

Images