CN115466995A - Method for improving gold plating thickness uniformity of ceramic substrate surface - Google Patents

Abstract

A method for improving the uniformity of gold plating thickness on the surface of a ceramic substrate belongs to the technical field of electroplating. The invention improves the uniformity of the thickness of the gold plating layer from the following three aspects: (1) Adding an ultrasonic function in the main gold plating groove, and starting ultrasonic vibration in the gold electroplating process; (2) The electroplating power supply adopts a single-pulse power supply, the off-period time of current is increased by reducing the duty ratio, the recovery time of the concentration of gold ions around the substrate is adjusted, and the uniformity of the thickness of the gold-plated layer is improved; (3) The content of gold ions in the main gold plating solution is controlled within (7-9) g/L. The problems that the existing ceramic substrate gold plating layer is poor in thickness uniformity, large in thickness difference between the substrate and the edge, difficult to control subsequent etching and poor in micro-assembly consistency after being prepared into a product are solved, so that the thickness uniformity of the ceramic substrate gold plating is improved, and the cost is saved. The method is widely applied to surface gold plating of the ceramic substrate, is used for improving the uniformity of a gold plating layer, and achieves the purposes of saving cost and improving the consistency of subsequent micro-assembly.

Description

A method for improving the uniformity of gold-plated thickness on the surface of a ceramic substrate

technical field

The invention belongs to the technical field of electroplating, and further relates to the technical field of gold plating on the surface of ceramic substrates, in particular to a method for improving the thickness uniformity of gold plating on the surface of ceramic substrates.

Background technique

Electroplating is the process of plating a thin layer of other metals or alloys on the surface of certain metals using the principle of electrolysis. The gold coating has stable chemical properties, is not easy to oxidize, and has low contact resistance. It can meet the requirements of micro-assembly processes such as gold wire ball welding or wedge welding. And many other advantages are becoming more and more popular. With the continuous development of microwave components, more and more products need to be gold-plated on the surface. Gold plating is highly reliable, but the cost is tens to hundreds of times higher than conventional nickel plating and tin plating. Therefore, how to control the uniformity of gold plating to reduce production costs is an important issue that needs to be considered for gold plating.

Microwave components are basically based on ceramics, and the size of the ceramic substrate is 1.5 inches to 4 inches. This type of ceramic substrate is gold-plated with a DC power supply for rack plating. Due to the tip effect of the current, the consistency of the gold layer thickness is poor, and the thickness of the gold layer between the edge and the center of the substrate is quite different. When the center of the chip reaches 3 μm, the thickness of the edge is often 4 μm. For precious metal plating, one is a waste of cost, and secondly, the uneven thickness will also affect the subsequent etching process. The process is difficult to control and the etching uniformity is poor. The consistency of micro-assembly after preparation into products is poor.

At present, in order to improve the uniformity of the gold-plated layer in the industry, some methods use auxiliary anodes. This method is complicated to implement and requires continuous design and adjustment. For ceramic substrates of different sizes, auxiliary anodes of different shapes need to be designed. This is extremely inconvenient for the gold-plated production of ceramic substrates with many varieties and specifications. Some methods improve the uniformity of the thickness of the gold plating layer by reducing the current density during electroplating of the product and controlling the deposition rate of the gold layer. However, this method will reduce the production efficiency on the one hand, and at the same time, the improvement of the thickness of the gold layer is relatively limited.

In view of this, the present invention is proposed.

Contents of the invention

The technical problem to be solved by the present invention is to solve the problems of poor uniformity of the thickness of the gold-plated layer of the existing ceramic substrate, large difference in thickness between the substrate and the edge, difficult control of subsequent etching, and poor consistency of micro-assembly after being prepared into products, thereby improving the ceramic substrate. Thickness uniformity of sheet gold plating and cost savings.

The inventive concept of the present invention is: the plating tank has a circulation filtering function, the gold-plating solution adopts a slightly cyanide-neutral gold-plating system, the anode adopts a platinum-titanium mesh, and special hangers are made respectively for ceramic substrates of different sizes, and the gold-plating process flow is as follows: Pre-plating treatment (oil removal and activation) → pre-gold plating → main gold plating → post-plating treatment (washing and drying). The uniformity of the film thickness of the gold-plated layer is improved from the following three aspects.

(1) Add an ultrasonic function to the main gold-plating tank, place an ultrasonic vibrating plate at the bottom of the tank, the vibrating plate is made of zirconium, the vibration frequency is 28KHz-40KHz, and the power is 1KW-2KW. The ultrasonic vibration is turned on during the electroplating process. Function to increase the uniformity of ion concentration in the plating tank, thereby improving the uniformity of the thickness of the gold-plated layer.

(2) Electroplating adopts a single pulse power supply, the frequency is 1000Hz-2000Hz, the duty is 20%-35%, the average current density of pre-plating gold is 0.6A/dm ² ±0.3A/dm ² , and the average current density of main gold-plating is 0.25 A/dm2～0.45A/dm2. The pulse power supply generally displays the average current, and its relationship with the pulse peak current is: I (average current) = I (peak current) × W (duty cycle). By reducing the duty cycle and increasing the off time of the current, it can help the recovery time of the concentration of gold ions around the substrate, thereby improving the uniformity of the thickness of the gold plating layer.

(3) Combined with reducing the duty cycle of the single pulse power supply to adjust the recovery time of the concentration of gold ions around the substrate, there are certain requirements for the concentration of gold ions, which cannot be too high or too low. A low concentration of gold ions will result in a small allowable current density, and the appearance of the gold layer is prone to redness and other poor appearance. A high concentration of gold ions will cause more gold to be brought out. At the same time, if the concentration is too high, the deep plating ability of the solution will be reduced. The gold ion content should be controlled in a relatively stable range. Through the principle of combining theoretical guidance and experimental verification, when the gold ion content (gold ion concentration) of the main gold plating solution is controlled at 7g/L to 9g/L, while ensuring production efficiency, the dispersion and throwing ability of the solution are also improved. Relatively good, so that the thickness uniformity of the gold-plated layer can be improved.

Through these three aspects of improvement, without affecting the production efficiency, the uniformity of the film thickness of the gold plating layer is improved, the production cost is saved, and the consistency of the subsequent micro-assembly of the product is also improved. Through this technical scheme for electroplating gold, the thickness of the gold layer for a 2-inch square sheet can achieve a non-uniformity <5%, and the coefficient of variation COV of the thickness of the gold layer is <2%. For a 4-inch square sheet, the unevenness of the gold layer is <6%. Coefficient of variation of thickness COV<3%.

For this reason, the invention provides a kind of method that improves the thickness uniformity of electroplated gold on ceramic substrate surface, comprises the steps:

Step 1: After installing the 1.5-inch to 4-inch ceramic substrate that has been sputtered with a thin layer of gold on the special hanger, the hanger is made of red copper, the whole is covered with glue, and the contact part of the hook is exposed;

The second step is to degrease the organic solvent, use analytical pure acetone to degrease, the substrate must be completely immersed in the acetone solution, the ultrasonic frequency is 28KHz ~ 40KHz, the current is 1A ~ 5A, and the soaking time is 3 minutes ~ 6 minutes;

Step 3: Clean the substrate, wash twice with deionized water, each cleaning time is 90s ~ 180s, the purpose is to remove the residual acetone on the surface of the substrate;

Step 4: Carry out alkaline chemical solvent electrolytic degreasing, the solution ratio is sodium hydroxide 18g/L～22g/L, sodium carbonate 22g/L～28g/L, sodium silicate 4g/L, the temperature is 55℃～ Cathodic electrolytic degreasing at 65°C for 4 to 6 minutes, with a current density of 1.8A/dm ² to 2.2A/dm ² , the purpose is to further remove oil stains on the surface of the substrate and obtain a clean and active surface.

Step 5: Clean the residual alkaline degreasing liquid on the surface of the substrate, and wash with deionized water twice, each cleaning time is 90s ~ 180s;

Step 6: Activate with citric acid with a concentration of 30g/L～60g/L for 3 minutes to 5 minutes, the purpose is to remove the oxide film on the metal surface of the substrate, activate the metal surface, and expose the active surface of the substrate to be plated. surface;

Step 7: Clean the residual activation solution on the surface of the substrate by washing with deionized water three times, each cleaning time is 90s ~ 180s;

Step 8: Pre-plating gold, using a single pulse power supply, the frequency is 1000Hz ~ 2000Hz, the duty is 20% ~ 35%, the current density is 0.3A/dm2 ~ 0.9A/dm2, the time is 30S, the role of pre-plating gold is mainly Improve the bonding force of the coating and prevent pollution of the main gold plating tank;

Step 9: Turn on the ultrasonic of the main gold-plating tank, the vibration frequency is 28KHz-40KHz, and the ultrasonic current is 1A-5A;

Step 10: Main gold plating, using a single pulse power supply, the frequency is 1000Hz-2000Hz, the duty is 20%-35%, the current density is 0.25A/dm2-0.45A/dm2, and the plating time is 5min-30min.

Step 11: Clean the substrate, remove the residual gold plating solution on the surface of the substrate, and wash with deionized water twice, each cleaning time is 90s~180s;

Step 12: Further clean the surface of the substrate, wash with ultrasonic deionized hot water, the temperature is 58°C-62°C, the ultrasonic frequency is 28KHz-40KHz, the ultrasonic current is 1A-5A, and the cleaning time is 90s-180s;

Step 13: Use analytical pure ethanol for dehydration treatment for 10s to 30s, and place the substrate on the drying jig after dehydration;

Step 14: Dry the substrate at a temperature of 65°C to 75°C and a drying time of 10min to 30min, and pack it into bags after drying;

Step 15: Measure the thickness of the gold layer. The thickness of each piece after electroplating gold is measured with a Fisher X-ray film thickness instrument, and the 9-point method is used for measurement, as shown in Figure 1.

Unevenness = [(T _{maximum value} - T _{minimum value} )/(2×T _{average value} )]×100%

In the formula, the average value of T is the _average thickness of the measured gold layer, the _{maximum value} of T and the _{minimum value} of T are the maximum and minimum values of the thickness of the gold layer, n is the number of measurement points, and COV is the coefficient of variation of the thickness of the gold layer. The smaller the unevenness and the COV value, the better the thickness uniformity of the electroplated gold layer.

Technical effect:

1. Through the cavitation effect of ultrasonic waves, the stirring effect of the solution is strengthened, and the uniformity of the ion concentration of the gold plating solution is improved;

2. By adopting a single pulse power supply, the current during electroplating is intermittently energized, so that the concentration of gold ions around the substrate has time to recover. By adjusting the duty cycle and frequency, the concentration of gold ions in the gold-plating solution itself does not change. High, so that the concentration of gold ions around the substrate has been kept in a stable range.

3. By controlling the gold ion concentration of the gold-plating solution to 7g/L-9g/L, the gold-plating solution has good dispersibility and throwing ability, improves the uniformity of the gold-plated film thickness, and improves product quality consistency and production efficiency. Because the low gold ion concentration will cause the allowable current density to be small, the appearance of the gold layer is prone to redness and other poor appearance, and the high gold ion concentration will cause more gold to be brought out. At the same time, if the concentration is too high, the deep plating ability of the solution will be reduced. Therefore, the gold ion content should be controlled at 7g/L-9g/L, which is a relatively stable range.

The invention is widely applied to the surface gold plating of ceramic substrates, and is used for improving the uniformity of the gold plating layer, achieving the purpose of saving costs and improving the consistency of subsequent micro-assembly.

Description of drawings

Figure 1 is a schematic diagram of the test point distribution.

detailed description

Described a kind of method that improves the thickness uniformity of gold plating on the ceramic substrate surface, the specific implementation method is as follows:

Implementation case 1:

2-inch square 99% alumina ceramic substrate (50.8mm×50.8mm×0.5mm) is electroplated with gold, the seed layer is TiW/Ni/Au, the number of single hanging pieces is 8 pieces, and the thickness of the gold layer is required to be 3 μm to 4 μm.

Step 1: After installing the 2-inch ceramic substrate that has been sputtered with a thin layer of gold on the special hanger, the hanger is made of red copper, the whole is covered with glue, and the contact part of the hook is exposed;

The second step is to carry out organic solvent degreasing, using analytical pure acetone for ultrasonic degreasing, the substrate must be completely immersed in the acetone solution, the ultrasonic frequency is 40KHz, the current is 2.5A, and the soaking time is 5 minutes;

Step 3: Clean the substrate, wash twice with deionized water, each cleaning time is 2 minutes, the purpose is to remove residual acetone on the surface of the substrate;

Step 4: Carry out alkaline chemical solvent electrolytic degreasing, the solution ratio is sodium hydroxide 18g/L～22g/L, sodium carbonate 22g/L～28g/L, sodium silicate 4g/L, the temperature is 55℃～ Cathodic electrolytic degreasing at 65°C for 4 to 6 minutes, with a current density of 1.8A/dm2 to 2.2A/dm2, the purpose is to further remove the oil on the surface of the substrate and obtain a clean and active surface;

Step 5: Clean the residual alkaline degreasing liquid on the surface of the substrate, and wash with deionized water twice, each cleaning time is 2 minutes;

Step 6: Use citric acid with a concentration of 30g/L~60g/L to activate for 3 minutes to 5 minutes. The purpose is to remove the oxide film on the metal surface of the substrate, activate the metal surface, and expose the active surface of the substrate to be plated. surface;

Step 7: Clean the residual activation solution on the surface of the substrate by washing with deionized water three times, each time for 2 minutes;

Step 8: Pre-plating gold, using a single pulse power supply, the frequency is 1500Hz, the duty cycle is 30%, the current density is 0.6A/dm ² , and the time is 30S. The role of pre-plating gold is mainly to improve the bonding force of the coating and prevent pollution. gold-plated tank;

Step 9: Turn on the ultrasonic of the main gold-plating tank, the vibration frequency is 40KHz, and the ultrasonic current is 1.8A;

Step 10: For main gold plating, use a single pulse power supply with a frequency of 1500Hz, a duty cycle of 30%, a current density of 0.35A/dm ² , and an electroplating time of 15 minutes;

Step 11: Clean the substrate, remove the residual gold plating solution on the surface of the substrate, and wash with deionized water twice, each cleaning time is 2 minutes;

Step 12: further clean the surface of the substrate, wash with ultrasonic deionized hot water, the temperature is 58 ℃ ~ 62 ℃, the ultrasonic frequency is 40KHz, the ultrasonic current is 3A, and the cleaning time is 2 minutes;

Step 13: Use analytical pure ethanol for dehydration treatment for 10s to 30s, and place the substrate on the drying jig after dehydration;

Step 14: Dry the substrate at a temperature of 65°C to 75°C for 20 minutes, and bag it after drying;

Step 15: Measure the thickness of the gold layer. For the thickness of each piece after electroplating, use a Fisher X-ray film thickness instrument to measure, and use the 9-point method as shown in the book. The measurement data is shown in Table 1.

Table 1 2-inch square film thickness data

Substrate number 1# 2# 3# 4# 5# 6# 7# 8# 9# 1 3.61 3.48 3.62 3.54 3.49 3.52 3.59 3.55 3.58 2 3.62 3.49 3.56 3.47 3.48 3.52 3.61 3.58 3.59 3 3.57 3.52 3.58 3.49 3.48 3.56 3.61 3.55 3.61 4 3.59 3.54 3.61 3.51 3.49 3.51 3.58 3.51 3.59 5 3.58 3.52 3.59 3.49 3.52 3.48 3.59 3.48 3.61 6 3.6 3.56 3.58 3.52 3.36 3.52 3.61 3.47 3.62 7 3.61 3.53 3.6 3.54 3.57 3.56 3.57 3.59 3.58 8 3.59 3.54 3.59 3.53 3.53 3.57 3.59 3.54 3.59

Calculated by the formula, it can be obtained that the _{average value} of T=3.55 μm, the _{maximum value} of T=3.62 μm, the _{minimum value} of T=3.36 μm, the unevenness=3.66%, and the COV=1.4%.

It can be seen that the thickness uniformity of the gold layer electroplated on the 2-inch square piece by this scheme is relatively good, the unevenness is 3.66%, and the COV is 1.4%.

Implementation case 2:

A 4-inch square 99% alumina ceramic substrate (101.6mm×101.6mm×0.5mm) is electroplated with gold, the seed layer is TaN/TiW/Au, and the thickness of the gold layer is required to be 4 μm to 5 μm.

Step 1: After installing the 4-inch ceramic substrate that has been sputtered with a thin layer of gold on the special hanger, the hanger is made of red copper, the whole is covered with glue, and the contact part of the hook is exposed;

The second step is to carry out organic solvent degreasing, using analytical pure acetone for ultrasonic degreasing, the substrate must be completely immersed in the acetone solution, the ultrasonic frequency is 40KHz, the current is 2.5A, and the soaking time is 5 minutes;

Step 3: Clean the substrate, wash twice with deionized water, each cleaning time is 2 minutes, the purpose is to remove residual acetone on the surface of the substrate;

Step 4: Carry out alkaline chemical solvent electrolytic degreasing, the solution ratio is sodium hydroxide 18g/L～22g/L, sodium carbonate 22g/L～28g/L, sodium silicate 4g/L, the temperature is 55℃～ Cathodic electrolytic degreasing at 65°C for 4 to 6 minutes, with a current density of 1.8A/dm2 to 2.2A/dm2. The purpose is to further remove the oil on the surface of the substrate and obtain a clean and active surface.

Step 5: Clean the residual alkaline degreasing liquid on the surface of the substrate, and wash with deionized water twice, each cleaning time is 2 minutes;

Step 6: Use citric acid with a concentration of 30g/L~60g/L to activate for 3 minutes to 5 minutes. The purpose is to remove the oxide film on the metal surface of the substrate, activate the metal surface, and expose the active surface of the substrate to be plated. surface;

Step 7: Clean the residual activation solution on the surface of the substrate by washing with deionized water three times, each time for 2 minutes;

Step 8: Pre-plating gold, using single pulse power supply, frequency 1200Hz, duty cycle 25%, current density 0.6A/dm ² , time 30S, the function of pre-plating gold is mainly to improve the bonding force of the coating and prevent pollution. gold-plated tank;

Step 9: Turn on the ultrasonic of the main gold-plating tank, the vibration frequency is 40KHz, and the ultrasonic current is 2A;

Step 10: For main gold plating, use a single pulse power supply with a frequency of 1200Hz, a duty cycle of 25%, a current density of 0.32A/dm ² and a plating time of 15 minutes.

Step 11: Clean the substrate, remove the remaining gold plating solution on the surface of the substrate, and wash with deionized water twice, each cleaning time is 2 minutes;

Step 12: further clean the surface of the substrate, wash with ultrasonic deionized hot water, the temperature is 58 ℃ ~ 62 ℃, the ultrasonic frequency is 40KHz, the ultrasonic current is 3A, and the cleaning time is 2 minutes;

Step 13: Use analytical pure ethanol for dehydration treatment for 10s to 30s, and place the substrate on the drying jig after dehydration;

Step 14: Dry the substrate at a temperature of 65°C to 75°C for 20 minutes, and bag it after drying;

Step 15: Measure the thickness of the gold layer. The thickness of each piece after electroplating is measured with a Fisher X-ray film thickness instrument. The 9-point method shown in Figure 1 is used for measurement, and the measurement data are shown in Table 2.

Table 2 4-inch square film thickness test data

Calculated by the formula, it can be obtained that the _{average value} of T=4.57 μm, the _{maximum value} of T=4.81 μm, the _{minimum value} of T=4.32 μm, the unevenness=5.36%, and the COV=2.97%.

It can be seen that the thickness uniformity of the gold layer electroplated by this scheme on the 4-inch square sheet is relatively good, with an unevenness of 5.36% and a COV of 2.97%.

Finally, it should be noted that the above-mentioned embodiments are only examples for clear description, and the present invention includes but is not limited to the above-mentioned embodiments, and it is not necessary and impossible to exhaustively describe all implementation modes here. For those of ordinary skill in the art, on the basis of the above description, other changes or changes in different forms can also be made. All implementations that meet the requirements of the present invention belong to the protection scope of the present invention.

Claims (9)

1. A method for improving the uniformity of gold-plated thickness on the surface of ceramic substrates. The plating tank has a circulating filter function. The gold-plating solution adopts a slightly cyanide-neutral gold-plating system, and the anode uses a platinum-titanium mesh. Special hangers are made for ceramic substrates of different sizes. Tool, the gold plating process is pre-plating treatment → pre-gold plating → main gold plating → post-plating treatment, which is characterized in that the uniformity of the thickness of the gold-plated layer is improved from the following three aspects: (1) Add ultrasonic function in the main gold plating tank, and turn on ultrasonic vibration during the electroplating process; (2) The electroplating power supply adopts a single-pulse power supply. By reducing the duty cycle and increasing the off-time of the current, the recovery time of the concentration of gold ions around the substrate is adjusted to improve the uniformity of the thickness of the gold-plated layer; (3) The gold ion content of the main gold plating solution is controlled within 7g/L-9g/L. 2. A method for improving the uniformity of gold-plated thickness on the surface of ceramic substrates as claimed in claim 1, characterized in that: the ultrasonic function is to place an ultrasonic vibrating plate on the bottom or side of the tank, the vibration frequency is 28KHz～40KHz, and the power 1KW ~ 2KW. 3. A method for improving the thickness uniformity of the gold plating on the surface of the ceramic substrate as claimed in claim 2, characterized in that: the material of the ultrasonic vibrating plate is zirconium. 4. A method for improving the uniformity of gold-plated thickness on the surface of ceramic substrates as claimed in claim 1, characterized in that: the frequency of the single pulse power supply is 1000Hz-2000Hz, the duty is 20%-35%, and the gold-plated The average current density is 0.6A/dm ² ±0.3A/dm ² , and the average current density of the main gold plating is 0.25A/dm ² to 0.45A/dm ² . 5. a kind of method for improving the uniformity of gold-plated thickness on ceramic substrate surface as claimed in claim 1, is characterized in that: concrete steps are as follows: Step 1: After installing the 1.5-inch to 4-inch square ceramic substrate that has been sputtered with a thin layer of gold on the special hanger, the hanger is made of red copper, the whole is covered with glue, and the contact part of the hook is exposed; Step 2 Carry out organic solvent degreasing, use analytical pure acetone for ultrasonic degreasing, the substrate must be completely immersed in the acetone solution, the ultrasonic frequency is 28KHz~40KHz, the current is 1A~5A, and the soaking time is 3 minutes~6 minutes; Step 3: Clean the substrate, wash twice with deionized water, each cleaning time is 90s ~ 180s, remove the residual acetone on the surface of the substrate; Step 4: Carry out alkaline chemical solvent electrolytic degreasing, the solution ratio is sodium hydroxide 18g/L～22g/L, sodium carbonate 22g/L～28g/L, sodium silicate 4g/L, the temperature is 55℃～ Cathodic electrolytic degreasing at 65°C for 4 to 6 minutes, with a current density of 1.8A/dm ² to 2.2A/dm ² ; Step 5: Clean the residual alkaline degreasing liquid on the surface of the substrate, and wash with deionized water twice, each cleaning time is 90s ~ 180s; Step 6: Activate with citric acid with a concentration of 30g/L-60g/L for 3 minutes to 5 minutes to remove the oxide film on the metal surface of the substrate, activate the metal surface, and expose the active surface on the surface of the substrate to be plated; Step 7: Clean the residual activation solution on the surface of the substrate by washing with deionized water three times, each cleaning time is 90s ~ 180s; Step 8: Pre-gold plating, using a single pulse power supply, the frequency is 1000Hz-2000Hz, the duty is 20%-35%, the current density is 0.3A/dm ² ～0.9A/dm ² , and the time is 30S; Step 9: Turn on the ultrasonic of the main gold-plating tank, the vibration frequency is 28KHz-40KHz, and the ultrasonic current is 1A-5A; Step 10: Main gold plating, using a single pulse power supply, the frequency is 1000Hz-2000Hz, the duty is 20%-35%, the current density is 0.25A/dm ² ～0.45A/dm ² , and the plating time is 5min-30min; Step 11: Clean the substrate, remove the residual gold plating solution on the surface of the substrate, and wash with deionized water twice, each cleaning time is 90s~180s; Step 12: Further clean the surface of the substrate, wash with ultrasonic deionized hot water, the temperature is 58°C-62°C, the ultrasonic frequency is 40KHz-28KHz, the ultrasonic current is 1A-5A, and the cleaning time is 90s-180s; Step 13: Use analytical pure ethanol for dehydration treatment for 10s to 30s, and place the substrate on the drying jig after dehydration; Step 14: Dry the substrate at a temperature of 65°C to 75°C and a drying time of 10min to 30min, and pack it into bags after drying; Step 15: Measure the thickness of the gold layer. For the thickness of each piece after electroplating gold, use the Fisher X-ray film thickness instrument to measure, and use the 9-point method to measure. 6. a kind of method improving the uniformity of gold-plated thickness on ceramic substrate surface as claimed in claim 5, is characterized in that: The first step: the ceramic substrate is a 2-inch square 99% alumina ceramic substrate, and the gold-plated seed layer is TiW/Ni/Au; The second step: the ultrasonic frequency is 40KHz, the current is 2.5A, and the soaking time is 5 minutes; The third step: each cleaning time is 2 minutes; The fifth step: each cleaning time is 2 minutes; The seventh step: each cleaning time is 2 minutes; The eighth step: the frequency is 1500Hz, the duty cycle is 30%, the current density is 0.6A/dm ² , and the time is 30S; The ninth step: the vibration frequency is 40KHz, and the ultrasonic current is 1.8A; The tenth step: the frequency is 1500Hz, the duty cycle is 30%, the current density is 0.35A/dm ² , and the electroplating time is 15 minutes; The 11th step: each cleaning time is 2 minutes; The 12th step: the ultrasonic frequency is 40KHz, the ultrasonic current is 3A, and the cleaning time is 2 minutes; The 14th step: the drying time is 20 minutes. 7. a kind of method for improving the uniformity of gold-plated thickness on ceramic substrate surface as claimed in claim 6 is characterized in that: the T _{average value} =3.55 μ m of described gold-plated thickness, T _{maximum value} =3.62 μ m, T _{minimum value} = 3.36 μm, unevenness=3.66%, COV=1.4%. 8. a kind of method improving the uniformity of gold-plated thickness on ceramic substrate surface as claimed in claim 5, is characterized in that: The first step: the ceramic substrate is a 4-inch square 99% alumina ceramic substrate, and the gold-plated seed layer is TaN/TiW/Au; The second step: the ultrasonic frequency is 40KHz, the current is 2.5A, and the soaking time is 5 minutes; The third step: each cleaning time is 2 minutes; The fifth step: each cleaning time is 2 minutes; The seventh step: each cleaning time is 2 minutes; The eighth step: the frequency is 1200Hz, the duty cycle is 25%, the current density is 0.6A/dm ² , and the time is 30S; The ninth step: the vibration frequency is 40KHz, and the ultrasonic current is 2A; The tenth step: the frequency is 1200Hz, the duty cycle is 25%, the current density is 0.32A/dm ² , and the electroplating time is 15 minutes; The 11th step: each cleaning time is 2 minutes; The 12th step: the ultrasonic frequency is 40KHz, the ultrasonic current is 3A, and the cleaning time is 2 minutes; The thirteenth step: using analytical pure anhydrous ethanol for dehydration treatment, the time is 10s-30s, after dehydration, place the substrate on the drying fixture; The 14th step: the drying time is 20 minutes. 9. a kind of method improving the uniformity of gold-plated thickness on ceramic substrate surface as claimed in claim 8 is characterized in that: the T _{average value} =4.57 μ m of described gold-plated thickness, T _{maximum value} =4.81 μ m, T _{minimum value} = 4.32 μm, unevenness=5.36%, COV=2.97%.

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