Method for removing silver-copper solder on ceramic surface

Abstract

The invention discloses a method for removing silver-copper solder on a ceramic surface. The method comprises the process of removing the silver-copper solder on the surface of a ceramic piece through electrochemical corrosion. In the electrochemical corrosion step, the ceramic part is connected with the anode of a power supply, the cathode is an insoluble pole part, and the silver-copper solder attached to the surface of the ceramic part is melted after electrification according to the principle of anode dissolution. According to the method, after the silver-copper solder layer on the ceramic metal surface is removed, the surface of the ceramic base is not discolored and corroded, the metal base material is not damaged, the sealing performance is not affected, and a good silver-copper solder removing effect can be achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of electrochemistry, and in particular relates to a method for removing silver-copper solder from the surface of ceramics. Background Art

[0002] Ceramic insulators have the characteristics of high mechanical strength, excellent dielectric properties at high temperature, good vacuum tightness, and low dielectric loss. They are widely used in the base of electronic relay housings.

[0003] The sintering process of the ceramic base is to position the metallized ceramic ring, the base plate, and the lead pins on the mold, fill the solder to the ceramic and the base plate, the ceramic and the lead pins, and melt the metallized layer together at high temperature to ensure the sealing of the base. However, due to the high temperature during sintering, the solder fluidity is not controlled during sintering, resulting in the problem of excess solder on the ceramic surface, and the solder is not visible visually. The solder component is only found under EDS energy spectrum scanning. This causes the base to be easily plated with a metal layer on the ceramic surface during electroplating, affecting the dielectric properties of the ceramic base. Therefore, pretreatment is required before plating the metal layer to remove the surface solder residue. The traditional process is to use sulfuric acid: nitric acid = 19:1 to remove the silver solder layer after degreasing, but due to the high corrosiveness to the base metal and the uncontrolled corrosion time, the base is over-corroded, which leads to sealing failure. Therefore, it is necessary to study the metal removal process of the ceramic surface of this type of parts, develop an electrochemical process that does not damage the sealing of the base, and meet the pretreatment process of ceramic base electroplating.

[0004] The patent document with announcement number CN116005163A discloses a method and device for processing silver-copper solder, which includes: placing the workpiece before electroplating in a processing tank for a first preset time to obtain a processed workpiece; placing a processing solution in the processing tank, the processing solution containing potassium permanganate; placing the processed workpiece in a reduction tank for reduction for a second preset time to obtain a reduced workpiece; placing a reducing solution in the reduction tank, the reducing solution containing ferrous sulfate; placing the reduced workpiece in a cleaning tank for a third preset time to obtain a cleaned workpiece; placing the cleaned workpiece in a pickling tank for a fourth preset time to obtain a pickled workpiece. However, potassium permanganate is used in the high method, and potassium permanganate has extremely strong oxidizing properties and is prone to damage the metal substrate. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a method for removing silver-copper solder on the surface of ceramics.

[0006] The present invention is achieved through the following technical solutions.

[0007] The invention provides a method for removing silver-copper solder on the surface of ceramics, which comprises a process of removing the silver-copper solder on the surface of ceramics by electrochemical corrosion.

[0008] Preferably, in the electrochemical corrosion step, the ceramic piece is connected to the anode of the power supply, and the cathode adopts an insoluble pole piece. After the ceramic piece is immersed in solution A, the silver-copper solder attached to the surface of the ceramic piece is ablated after power is applied.

[0009] Preferably, the solution A comprises phosphoric acid, sulfuric acid, oxalic acid, thiourea and water.

[0010] Preferably, the phosphoric acid content is 600-620 ml / L, the sulfuric acid content is 180-220 ml / L, the oxalic acid content is 10-15 g / L, the thiourea content is 8-12 g / L, and the water content is 180-220 ml / L.

[0011] Preferably, the current density in the electrochemical corrosion step is 3 to 5 A / dm 2 , time 5 to 8 minutes.

[0012] Preferably, after the electrochemical corrosion step is completed, the ceramic part is cleaned and activated, and after the activation is completed, it is rinsed, and then nickel plating and gold plating steps are carried out in sequence, and then it is cleaned and dried.

[0013] Preferably, after the electrochemical corrosion step is completed, the ceramic part is washed with deionized water for 3 to 6 minutes, and then placed in 40 to 60% hydrochloric acid for activation. After the activation is completed, the ceramic part is rinsed with running water for 3 to 6 minutes, and then nickel-plated and gold-plated in sequence, and then rinsed with running water for 3 to 6 minutes and dried.

[0014] Preferably, the nickel plating step comprises using 270-330 g / L nickel sulfamate, 15-30 g / L nickel chloride and 30-45 g / L boric acid to plate nickel at a temperature of 40-50° C. and a pH of 3.5-4.2 for 10-30 min.

[0015] Preferably, the gold plating step includes using 4-6 g / L of gold and 650-750 mL / L of additives at a temperature of 30-35° C. and a pH of 4-4.3 for gold plating for 10-30 minutes, and the specific gravity is 1.18-1.22.

[0016] Preferably, the insoluble pole piece is an insoluble ruthenium-iridium-titanium mesh.

[0017] The beneficial effects of the present invention are:

[0018] In the electrochemical corrosion step of the present invention, the ceramic part is connected to the anode of the power supply, and the cathode adopts an insoluble pole part. The silver-copper solder attached to the surface of the ceramic part is ablated after power is turned on by utilizing the principle of anode dissolution. After the silver-copper solder layer on the surface of the ceramic metal is removed by the method of the present invention, the surface of the ceramic base does not change color or corrode, and the metal substrate is not damaged, and the sealing is not affected, and a good silver-copper solder removal effect can be achieved. DETAILED DESCRIPTION

[0019] The technical solution of the present invention is further described below, but the scope of protection claimed is not limited to the description.

[0020] Embodiment 1:

[0021] A method for removing silver-copper solder from a ceramic surface comprises a process of removing the silver-copper solder from the ceramic surface by electrochemical corrosion.

[0022] In the electrochemical corrosion step, the ceramic piece is connected to the anode of the power supply, and the cathode is an insoluble pole piece. After the ceramic piece is immersed in solution A, the silver-copper solder attached to the surface of the ceramic piece is ablated after power is applied based on the principle of anode dissolution.

[0023] The solution A includes phosphoric acid, sulfuric acid, oxalic acid, thiourea and water.

[0024] The phosphoric acid content is 600 ml / L, the sulfuric acid content is 180 ml / L, the oxalic acid content is 10 g / L, the thiourea content is 8 g / L, and the water content is 180 ml / L.

[0025] The current density in the electrochemical corrosion step is 3A / dm 2 , time 5 minutes.

[0026] After the electrochemical corrosion step is completed, the ceramic part is cleaned and activated. After the activation is completed, it is rinsed, and then nickel plating and gold plating steps are performed in sequence, and then it is cleaned and dried.

[0027] After the electrochemical corrosion step is completed, the ceramic part is cleaned with deionized water for 3 minutes until no acid residue remains on the surface, and then placed in 40% hydrochloric acid for activation. After the activation is completed, the ceramic part is rinsed with running water for 3 minutes until no acid residue remains on the surface, and nickel and gold are plated in sequence. The ceramic part is rinsed with running water for 3 minutes until no acid residue remains on the surface, and then dried. The ceramic part is observed under a 5-10 times microscope to ensure that there is no coating layer on the surface.

[0028] The nickel plating step includes using 270 g / L nickel sulfamate, 15 g / L nickel chloride and 30 g / L boric acid to plate nickel for 10 minutes at a temperature of 40° C. and a pH of 3.5.

[0029] The gold plating step includes using 4 g / L gold and 650 mL / L gold-cobalt alloy C additive to plate gold for 10 minutes at a temperature of 30° C. and a pH of 4, and the specific gravity is 1.18. The gold-cobalt alloy C additive is prepared by the prior art.

[0030] The insoluble pole piece is an insoluble ruthenium-iridium-titanium mesh.

[0031] Embodiment 2:

[0032] A method for removing silver-copper solder from a ceramic surface comprises a process of removing the silver-copper solder from the ceramic surface by electrochemical corrosion.

[0033] In the electrochemical corrosion step, the ceramic piece is connected to the anode of the power supply, and the cathode is an insoluble pole piece. After the ceramic piece is immersed in solution A, the silver-copper solder attached to the surface of the ceramic piece is ablated after power is applied based on the principle of anode dissolution.

[0034] The solution A includes phosphoric acid, sulfuric acid, oxalic acid, thiourea and water.

[0035] The phosphoric acid content is 620 ml / L, the sulfuric acid content is 220 ml / L, the oxalic acid content is 15 g / L, the thiourea content is 12 g / L, and the water content is 220 ml / L.

[0036] The current density in the electrochemical corrosion step is 5A / dm 2 , time 8 minutes.

[0037] After the electrochemical corrosion step is completed, the ceramic part is cleaned and activated. After the activation is completed, it is rinsed, and then nickel plating and gold plating steps are performed in sequence, and then it is cleaned and dried.

[0038] After the electrochemical corrosion step is completed, the ceramic part is cleaned with deionized water for 6 minutes until no acid residue remains on the surface, and then placed in 60% hydrochloric acid for activation. After the activation is completed, the ceramic part is rinsed with running water for 6 minutes until no acid residue remains on the surface, and nickel is plated for 20 minutes and gold is plated for 20 minutes in sequence. The ceramic part is then rinsed with running water for 6 minutes until no acid residue remains on the surface, and then dried. The ceramic part is observed under a 5-10 times microscope to confirm that there is no coating on the surface.

[0039] The nickel plating step includes using 330 g / L nickel sulfamate, 30 g / L nickel chloride and 45 g / L boric acid to plate nickel for 30 minutes at a temperature of 50° C. and a pH of 4.2.

[0040] The gold plating step includes using 6 g / L gold and 750 mL / L gold-cobalt alloy C additive to plate gold for 30 minutes at a temperature of 35° C. and a pH of 4.3, and the specific gravity is 1.22. The gold-cobalt alloy C additive is prepared by the prior art.

[0041] The insoluble pole piece is an insoluble ruthenium-iridium-titanium mesh.

[0042] Embodiment 3:

[0043] A method for removing silver-copper solder from a ceramic surface comprises a process of removing the silver-copper solder from the ceramic surface by electrochemical corrosion.

[0044] In the electrochemical corrosion step, the ceramic piece is connected to the anode of the power supply, and the cathode is an insoluble pole piece. After the ceramic piece is immersed in solution A, the silver-copper solder attached to the surface of the ceramic piece is ablated after power is applied based on the principle of anode dissolution.

[0045] The solution A includes phosphoric acid, sulfuric acid, oxalic acid, thiourea and water.

[0046] The phosphoric acid content is 610 ml / L, the sulfuric acid content is 200 ml / L, the oxalic acid content is 13 g / L, the thiourea content is 11 g / L, and the water content is 210 ml / L.

[0047] The current density in the electrochemical corrosion step is 4A / dm 2 , time 6 minutes.

[0048] After the electrochemical corrosion step is completed, the ceramic part is cleaned and activated. After the activation is completed, it is rinsed, and then nickel plating and gold plating steps are performed in sequence, and then it is cleaned and dried.

[0049] After the electrochemical corrosion step is completed, the ceramic part is cleaned with deionized water for 5 minutes until no acid residue remains on the surface, and then placed in 50% hydrochloric acid for activation. After the activation is completed, the ceramic part is rinsed with running water for 4 minutes until no acid residue remains on the surface, and nickel is plated for 20 minutes and gold is plated for 20 minutes in sequence. The ceramic part is then rinsed with running water for 4 minutes until no acid residue remains on the surface, and then dried. The ceramic part is observed under a 5-10 times microscope to confirm that there is no coating on the surface.

[0050] The nickel plating step includes using 300 g / L nickel sulfamate, 24 g / L nickel chloride and 40 g / L boric acid to plate nickel for 20 minutes at a temperature of 45° C. and a pH of 3.9.

[0051] The gold plating step includes using 5 g / L gold and 700 mL / L gold-cobalt alloy C additive to plate gold for 20 minutes at a temperature of 33° C. and a pH of 4.1, and the specific gravity is 1.21. The gold-cobalt alloy C additive is prepared by the prior art.

[0052] The insoluble pole piece is an insoluble ruthenium-iridium-titanium mesh.

[0053] After cleaning, the electronic relay housing base and the corresponding cover can be laser sealed and tested for sealing. The leakage rate of the sealing test is not higher than 1×10 -9 Pa.m 3 / s is qualified, and the results are shown in the following table.

[0054] Example 1 Example 2 Example 3 <![CDATA[3.59×10 -10 Pa.m 3 / s]]> <![CDATA[3.44×10 -10 Pa.m 3 / s]]> <![CDATA[1.95×10 -10 Pa.m 3 / s]]> <![CDATA[2.66×10 -10 Pa.m 3 / s]]> <![CDATA[3.15×10 -10 Pa.m 3 / s]]> <![CDATA[3.01×10 -10 Pa.m 3 / s]]> <![CDATA[1.69×10- 10 Pa.m 3 / s]]> <![CDATA[2.33×10 -10 Pa.m 3 / s]]> <![CDATA[2.84×10 -10 Pa.m 3 / s]]>

[0055] As can be seen from the above table, the ceramic parts whose surface silver-copper solder is removed by the method of the present application have better sealing properties.

[0056] The method of the present application is suitable for removing silver-copper solder from the surface of a ceramic insulator on a housing base of an electronic relay.

Claims

1. A method for removing silver-copper solder from a ceramic surface, characterized in that: It includes the process of removing silver-copper solder on the surface of ceramic parts by electrochemical corrosion.

2. A method for removing silver-copper solder from a ceramic surface as claimed in claim 1, characterized in that: In the electrochemical corrosion step, the ceramic piece is connected to the anode of the power supply, and the cathode is an insoluble pole piece. After the ceramic piece is immersed in solution A, the silver-copper solder attached to the surface of the ceramic piece is ablated after power is applied.

3. A method for removing silver-copper solder from a ceramic surface as claimed in claim 2, characterized in that: The solution A includes phosphoric acid, sulfuric acid, oxalic acid, thiourea and water.

4. A method for removing silver-copper solder from a ceramic surface as claimed in claim 3, characterized in that: The phosphoric acid content is 600-620 ml / L, the sulfuric acid content is 180-220 ml / L, the oxalic acid content is 10-15 g / L, the thiourea content is 8-12 g / L, and the water content is 180-220 ml / L.

5. A method for removing silver-copper solder from a ceramic surface as claimed in claim 1, characterized in that: The current density in the electrochemical corrosion step is 3 to 5 A / dm 2 , time 5 to 8 minutes.

6. A method for removing silver-copper solder from a ceramic surface as claimed in claim 1, characterized in that: After the electrochemical corrosion step is completed, the ceramic part is cleaned and activated. After the activation is completed, it is rinsed, and then nickel plating and gold plating steps are performed in sequence, and then it is cleaned and dried.

7. A method for removing silver-copper solder from a ceramic surface as claimed in claim 6, characterized in that: After the electrochemical corrosion step is completed, the ceramic part is cleaned with deionized water for 3 to 6 minutes, and then placed in 40 to 60% hydrochloric acid for activation. After the activation is completed, the ceramic part is rinsed with running water for 3 to 6 minutes, and nickel and gold are plated in sequence. The ceramic part is then rinsed with running water for 3 to 6 minutes and then dried.

8. A method for removing silver-copper solder from a ceramic surface as claimed in claim 7, characterized in that: The nickel plating step includes using 270-330 g / L of nickel sulfamate, 15-30 g / L of nickel chloride and 30-45 g / L of boric acid to plate nickel for 10-30 minutes at a temperature of 40-50° C. and a pH of 3.5-4.

2.

9. A method for removing silver-copper solder from a ceramic surface as claimed in claim 7, characterized in that: The gold plating step includes using 4-6 g / L of gold and 650-750 mL / L of additives to plate gold for 10-30 minutes at a temperature of 30-35° C. and a pH of 4-4.3, and the specific gravity is 1.18-1.

22.

10. A method for removing silver-copper solder from a ceramic surface as claimed in claim 2, characterized in that: The insoluble pole piece is an insoluble ruthenium-iridium-titanium mesh.