CN112251782A

CN112251782A - Method, device and product for local gold electroplating

Info

Publication number: CN112251782A
Application number: CN202011192431.4A
Authority: CN
Inventors: 孙志明; 郭志平
Original assignee: Shenzhen Honggang Mechanism & Equipment Co ltd
Current assignee: Shenzhen Honggang Mechanism & Equipment Co ltd
Priority date: 2020-10-30
Filing date: 2020-10-30
Publication date: 2021-01-22

Abstract

The invention provides a method, a device and a product for local gold electroplating, wherein the method adopts bidirectional pulse square wave current, and electroplating is carried out by additionally arranging an insulating shielding part after pre-plating a gold layer with the thickness of 0.01-0.03 mu m on a workpiece, so that the thickness of a gold-plating layer in a shielding area can be reduced, the gold consumption is saved, and the gold-plating layer is uniform; the method for local gold electroplating is simple to operate and low in cost.

Description

Method, device and product for local gold electroplating

Technical Field

The invention relates to the field of electroplating, in particular to a method, a device and a product for local gold electroplating.

Background

Gold plating has been known for over two hundred years. The gold plating layer has golden yellow appearance, good chemical stability, discoloration resistance, conductivity, corrosion resistance and oxidation resistance, good weldability, low contact resistance and excellent hot-pressing bonding performance, so that the electroplated gold plating layer can be used as a decorative plating layer and a functional and protective plating layer. Therefore, the electrogilding is widely applied to the industrial fields of jewelry, clocks, artware, electronics, instruments, aviation, aerospace and the like. Gold is a relatively expensive plating that has a very low resistivity and provides a very low surface contact resistance because it does not form surface oxides. Gold is a very soft metal, and a gold-plated layer with a purity of 99.99% (24K) is easily deformed under load and also easily bonded to another gold surface (cold welding). The coating has good ductility and is easy to polish, and is widely applied to electroplating of parts requiring long-term stable electrical parameter performance, such as precision instruments, printing plates, integrated circuits, electronic tube shells, electric contacts and the like. However, gold is expensive, and thus, the application is limited.

CN104582299A discloses a method for local shielding electroplating by using a film, but the method has the following disadvantages: (1) the adhesive film is easy to wash away in the previous washing process. (2) Since there is a step at the boundary between the portion to which the film is attached and the portion where the surface of the work is exposed, it is difficult to completely remove the treatment solution remaining at the step in the water washing step, and there is a problem in that a streak of impurities is likely to remain after plating, which not only impairs the appearance, but also causes a structural problem such as corrosion from the portion. (3) The mode of adopting the pad pasting can only cause the effect of complete shielding to this shielding region, can not play the effect that reduces gilt thickness.

The prior art adopts direct current electroplating for gold electroplating, but the direct current electroplating has the problems of poor binding force, low hardness, poor wear resistance, low dynamic load bearing capacity, low impact capacity and the like.

Therefore, there is still a need to develop a method for local gold electroplating with uniform thickness of the shielding region, high binding force, good wear resistance, high dynamic load bearing and impact resistance, etc.

Disclosure of Invention

Summary of The Invention

The invention aims to provide a method for local gold electroplating, which reduces the thickness of a gold-plated layer in a shielding area and saves the gold consumption by arranging a shielding part outside the surface of the area to be shielded at a certain gap; furthermore, by limiting the size of the gap between the shielding part and the cathode, the gold plating layer on the shielding area is uniform, and the transition between the non-shielding area and the shielding area is natural. The method for local gold electroplating is simple to operate and low in cost, and the thickness of the shielding area of the prepared product is uniform and consistent.

Another object of the present invention is to provide a local electrogilding device and product, wherein the device and product have higher binding force between the electrogilding layer and the workpiece, better wear resistance of the electrogilding layer, and higher dynamic load and impact bearing capacity by electroplating with bidirectional pulse square wave current compared with the direct current used in the prior art.

Detailed Description

In a first aspect, the present invention provides a method for local electroplating of gold.

A method of local electroplating of gold comprising the steps of: s10, connecting the workpiece to be locally plated with the gold layer with a cathode, immersing the workpiece into an electroplating bath provided with an anode and electroplating solution, and electroplating a gold layer with the thickness of 0.01-0.03 mu m on the surface of the workpiece in advance; s20, arranging an electrically insulated shielding component in the region to be shielded of the workpiece oppositely, and then carrying out electroplating, wherein a gap exists between the shielding component and the region to be shielded of the workpiece; the workpiece can be locally electroplated by adopting the electrically insulated shielding component, and the thickness of an electroplated layer in a shielding area on the workpiece is thinner than that of an electroplated layer in a non-shielding area, so that the thickness of a gold-plated layer in the shielding area can be reduced, and the gold consumption is saved; the surface of the workpiece is electroplated with a gold layer with the thickness of 0.01-0.03 mu m in advance, and the method has the advantages of the following aspects: 1. the binding force of the plating layer is ensured; 2. the possibility of pollution of the positive gold plating groove is reduced; 3. the compactness of the gold plating layer is improved; 4. reducing the possibility of local blushing.

The size of the gap may be 1.0-1.9 mm. The smaller the gap, the smaller the plating thickness of the shielded area, and the preferred size of the gap is 1.0-1.9mm, all other things being equal. When the gap is smaller than 1.0mm, the boundary line between the shielding area and the non-shielding area on the workpiece is obvious, and the electroplating thickness of the shielding area is too thin; when the clearance is greater than 1.9mm, the shielding region electroplating thickness can be bigger than normal, the shielding effect is difficult to achieve, and the shielding region is difficult to form a uniform electroplated layer.

The shielding member is detachable. The shielding component is detachable, so that the operation is more convenient during electroplating.

The gap between the shielding component and the cathode is adjustable; the shielding component is arranged to be adjustable and to be electroplated to the gap between the workpieces, so that the operation is more convenient during electroplating, and local electroplating products with different thicknesses in the shielding region can be obtained by adjusting the gap between the shielding component and the workpieces to be electroplated.

The shielding member may be at least one piece.

The shielding component and the workpiece are placed in the direction that the plate surfaces of the shielding component and the workpiece are approximately parallel to each other.

The shielding component can be made of a hydrophobic material, and the hydrophobic material can avoid loss caused by taking out liquid in the groove when the shielding component is taken out.

The shielding component can be designed into shielding components with different shapes according to different areas of the shielding area and the non-shielding area of the workpiece.

The current electroplated in the step S10 and/or the step S20 can be bidirectional pulse square wave current, and the bidirectional pulse square wave current is adopted, so that on one hand, the pores of the plating layer can be reduced, the bonding force of the plating layer can be improved, the electroplating efficiency can be improved, the intermittent output is realized, the solution ion recovery is facilitated, and the corrosion resistance of the plating layer is enhanced; on the other hand, the bidirectional pulse square wave current can obviously improve the thickness distribution of the coating to ensure uniform thickness, can meet the specified technical indexes of binding force, wear resistance, dynamic load bearing capacity, impact resistance and the like while realizing a thinner coating, and can save 15-20% of gold.

The plating bath in said steps S10 and/or S20 may contain a water-soluble gold salt in an amount of 2.5g/L calculated as gold ion concentration and thallium compound in an amount of 0.05 to 0.1g/L calculated as thallium ion concentration.

The water-soluble gold salt may include at least one of gold potassium cyanide, gold sodium sulfite, gold potassium chloride, gold sodium chloride, gold ammonium chloride, gold potassium cyanide, gold sodium cyanide, gold ammonium cyanide, gold hydroxide, and gold oxide.

The thallium compound may include at least one of thallium acetate, thallium sulfate, thallium nitrate, thallium formate, or thallium malonate.

The parameters of the bidirectional pulse square wave current comprise: pulse current density, current frequency, forward and reverse current duty ratio and duty cycle.

The pulse current density of the bidirectional pulse square wave current can be 0.1-0.2A/dm²。

The current frequency of the bidirectional pulse square wave current can be 50-1000 Hz.

The working time ratio of forward current to reverse current of the bidirectional pulse square wave current can be 10: 1.

The duty cycle of the bidirectional pulse square wave current can be 20-30%.

The parameters of the bidirectional pulse square wave currents of the steps S10 and S20 may be the same or different.

The anode may be a platinum titanium mesh.

The time for the electroplating in the step S20 may be 5 to 10 minutes.

The workpiece to be partially electroplated with a gold layer may include a nickel-plated layer, the gold-plated layer being electroplated on a surface of the nickel-plated layer.

The method of partially plating gold may further include performing a surface treatment after the plating of step S20. In some embodiments, the surface treatment comprises a cleaning and/or discoloration prevention treatment. In some embodiments, the cleaning is performed by pure water or hot pure water, and the cleaning is used for eliminating residual salts on the surface of the coating and maintaining the lasting gloss of the coating. The discoloration prevention treatment can seal the pores of the gold plating layer to prevent the gold plating layer from discoloring due to the fact that the gold bottom layer is corroded and corrosion products are spread to the surface.

The method for local gold plating may further include baking after the cleaning and/or discoloration prevention treatment.

According to some embodiments of the invention, a method of local electroplating of gold comprises the steps of: s10, connecting the workpiece to be locally plated with the gold layer with a cathode, immersing the workpiece into an electroplating bath provided with an anode and electroplating solution, and electroplating a gold layer with the thickness of 0.01-0.03 mu m on the surface of the workpiece in advance; s20, arranging an electrically insulated shielding component in the region to be shielded of the workpiece oppositely, and then carrying out electroplating, wherein a gap exists between the shielding component and the region to be shielded of the workpiece; the gap is 1.0-1.9 mm.

According to some embodiments of the invention, a method of local electroplating of gold comprises the steps of: s10, connecting the workpiece to be locally plated with the gold layer with a cathode, immersing the workpiece into an electroplating bath provided with an anode and electroplating solution, and electroplating a gold layer with the thickness of 0.01-0.03 mu m on the surface of the workpiece in advance; s20, arranging an electrically insulated shielding component in the region to be shielded of the workpiece oppositely, and then carrying out electroplating, wherein a gap exists between the shielding component and the region to be shielded of the workpiece; the current electroplated in the step S10 and/or S20 is bidirectional pulse square wave current; the parameters of the bidirectional pulse square wave current comprise: pulse current density, current frequency, forward and reverse current working time ratio and duty ratio; the pulse current density of the bidirectional pulse square wave current is 0.1-0.2A/dm²(ii) a The current frequency of the bidirectional pulse square wave current is 50-1000 Hz; the working time ratio of forward current to reverse current of the bidirectional pulse square wave current is 10:1, and the duty ratio of the bidirectional pulse square wave current is 20-30%; the parameters of the bidirectional pulse square wave currents of the steps S10 and S20 may be the same or different.

According to some embodiments of the invention, a method of local electroplating of gold comprises the steps of: s10, connecting the workpiece to be locally plated with the gold layer with a cathode, immersing the workpiece into an electroplating bath provided with an anode and electroplating solution, and electroplating a gold layer with the thickness of 0.01-0.03 mu m on the surface of the workpiece in advance; s20, arranging an electrically insulated shielding component in the region to be shielded of the workpiece oppositely, and then carrying out electroplating, wherein a gap exists between the shielding component and the region to be shielded of the workpiece; the clearance between the shielding component and the workpiece is 1.0-1.9 mm; the electroplating current in the step S10 and/or S20 is bidirectional pulse square wave current; the parameters of the bidirectional pulse square wave current comprise: pulse current density, current frequency, forward and reverse current working time ratio and duty ratio; the pulse current density of the bidirectional pulse square wave current is 0.1-0.2A/dm²(ii) a The current frequency of the bidirectional pulse square wave current is 50-1000 Hz; the working time ratio of forward current to reverse current of the bidirectional pulse square wave current is 10:1, and the duty ratio of the bidirectional pulse square wave current20 to 30 percent; the parameters of the bidirectional pulse square wave currents of the steps S10 and S20 may be the same or different.

The workpiece may be of various shapes. The workpiece may have various shapes such as a flat plate shape, a cylindrical shape, and an elliptical shape.

The shielding member may be a single member or may be a divided member.

The workpiece and the shielding component can be arranged after the electroplating hanger and then immersed into the electroplating bath for electroplating.

In a second aspect, the present invention provides a product prepared according to any of the above methods.

In a third aspect, the present invention provides a local electroplating apparatus, which includes an anode, a cathode, an electroplating bath, a detachable shielding member and an adjustable gap with the workpiece to be electroplated, wherein the shielding member is made of an electrically insulating material, the shielding member is located at a position opposite to the surface of the region to be shielded of the cathode, and a gap exists between the shielding member and the surface of the region to be shielded of the cathode.

Advantageous effects

(1) By arranging the shielding part between the anode and the cathode, the thickness of the non-shielding region can be ensured, the thickness of the gold-plating layer of the shielding region can be reduced, and the gold consumption can be saved.

(2) Furthermore, by limiting the gap between the shielding part and the cathode to be 1.0-1.9mm, the gold plating layer on the shielding area is uniform and consistent, and the transition between the non-shielding area and the shielding area is natural. The method for local gold electroplating is simple to operate and low in cost, and the thickness of the shielding area of the prepared product is uniform and consistent.

(3) The invention preplates a layer of gold layer with the thickness of 0.01-0.03 μm on the surface of the workpiece, and has the advantages of the following aspects: 1. the binding force of the plating layer is ensured; 2. the possibility of pollution of the positive gold plating groove is reduced; 3. the compactness of the gold plating layer is improved; 4. reducing the possibility of local blushing.

(4) The shielding component is arranged to be detachable and adjustable and to be electroplated in the gap between the workpieces, so that the operation is more convenient during electroplating, and local electroplating products with different thicknesses in the shielding area can be obtained by adjusting the shielding component and to be electroplated in the gap between the workpieces.

(5) Compared with the direct current adopted in the prior art, the invention adopts the bidirectional pulse square wave current and the most appropriate current parameters, on one hand, the invention can reduce the plating layer pores, improve the plating layer binding force, improve the electroplating efficiency, output intermittently, be beneficial to the solution ion recovery and enhance the corrosion resistance of the plating layer; on the other hand, the bidirectional pulse square wave current can obviously improve the thickness distribution of the coating to ensure uniform thickness, and can meet the technical indexes of specified binding force, abrasion resistance, dynamic load bearing capacity, impact resistance and the like while realizing a thinner coating.

(6) The invention discloses the most suitable bidirectional pulse square wave current parameters, improves the working efficiency, ensures that the thickness of a plating layer is in a proper range, and ensures that the plating layer has higher binding force, wear resistance, dynamic load bearing capacity, impact capacity and other performances.

Description of the terms

In the present invention, mm represents mm; μ m means μm; a/dm²Representing amperes per square decimeter; g/L represents grams per liter; hz means Hertz; "duty cycle" means the proportion of the energization time relative to the total time within one pulse cycle.

In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; the two elements may be directly connected or indirectly connected through an intermediate medium, or may be communicated with each other inside the two elements, or may be wirelessly connected or wired connected. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

Drawings

Fig. 1 is a front view of a plating hanger equipped with a shield member and a workpiece in example 1 and example 2.

Fig. 2 shows a left side view of a plating hanger of embodiment 1 and embodiment 2, which is equipped with a shield member and a workpiece.

FIG. 3 is a flow chart showing a method of local gold plating according to examples 1 and 2.

Detailed Description

In order to make the technical solutions of the present invention better understood by those skilled in the art, some non-limiting examples are further disclosed below, and the present invention is further described in detail.

The reagents used in the present invention are either commercially available or can be prepared by the methods described herein.

Referring to fig. 1-3, the present invention provides a method for local electroplating gold, comprising the following steps:

s10, connecting the workpiece (1) to be locally plated with the gold layer to a cathode, immersing the workpiece into an electroplating bath provided with an anode and electroplating liquid, and electroplating a gold layer with the thickness of 0.01-0.03 mu m on the surface of the workpiece (1) in advance;

s20, an electric insulation shielding component (2) is oppositely arranged on the region to be shielded of the workpiece (1), then electroplating is carried out, and a gap (X) exists between the shielding component (2) and the region to be shielded of the workpiece (1).

Example 1:

electroplating solution: the water-soluble gold salt was contained at 2.5g/L as calculated as gold ion concentration and the thallium compound was contained at 0.05g/L as calculated as thallium ion concentration.

The operation is as follows: the operation is performed according to steps S10 and S20, wherein the bidirectional pulse square wave current in steps S10 and S20 is a plating current with the following parameters: the pulse current density is 0.1A/dm²The method comprises the steps that a current frequency is 100Hz, a forward and reverse current working time ratio is 10:1, a current duty ratio is 20%, a gold layer with the thickness of about 0.02 mu m is electroplated on the surface of a workpiece (1), and then the operation of step S20 is carried out, wherein in the step S20, the plate surfaces of the workpiece (1) and a shielding component (2) are approximately parallel to the plate surface of an anode of an electroplating bath, the size of a gap (X) is 1.0mm, the electroplating time is 5 minutes, and a final product is obtained after cleaning and baking.

Example 2:

The operation is as follows: the operation is performed according to steps S10 and S20, wherein the bidirectional pulse square wave current in steps S10 and S20 is a plating current with the following parameters: the pulse current density is 0.1A/dm²The current frequency is 100Hz, the working time ratio of forward current to reverse current is 10:1, the duty ratio of the current is 20%, a gold layer with the thickness of about 0.02 mu m is electroplated on the surface of the workpiece (1) in advance, and then the operation of step S20 is carried out, wherein the plate surfaces of the workpiece (1) and the shielding component (2) are approximately parallel to the plate surface of the anode of the electroplating bath in step S20, the size of the gap (X) is 1.9mm, the electroplating time is 5 minutes, and the final product is obtained after cleaning and baking.

Comparative example 1:

The operation is as follows: connecting a workpiece to be locally plated with a gold layer to a cathode, immersing the workpiece into a plating bath provided with the anode and a plating solution, taking bidirectional pulse square wave current as plating current, and setting the pulse current density to be 0.1A/dm²The method comprises the steps that the current frequency is 100Hz, the forward and reverse current working time ratio is 10:1, the current duty ratio is 20%, after a gold layer with the thickness of about 0.02 mu m is electroplated on the surface of a workpiece in advance, an electrically insulated shielding component is oppositely arranged in a region to be shielded of the workpiece, a gap exists between the shielding component and the region to be shielded of the workpiece, and the size of the gap is 0.5 mm. Immersing the workpiece and the shielding component into the electroplating bath again, wherein the plate surfaces of the workpiece and the shielding component are approximately parallel to the plate surface of the anode of the electroplating bath, the bidirectional pulse square wave current is used as the electroplating current, and the pulse current density is set to be 0.1A/dm²Electroplating at current frequency of 100Hz, forward/reverse current working time ratio of 10:1 and current duty ratio of 20%, wherein the electroplating time is 5 min, and cleaning and baking to obtain the final product.

Comparative example 2:

The operation is as follows: connecting a workpiece to be locally plated with a gold layer to a cathode, immersing the workpiece into a plating bath provided with the anode and a plating solution, taking bidirectional pulse square wave current as plating current, and setting the pulse current density to be 0.1A/dm²The method comprises the steps of pre-plating a gold layer with the thickness of about 0.02 mu m on the surface of a workpiece, arranging an electrically insulated shielding component in a region to be shielded of the workpiece oppositely after pre-plating the gold layer with the thickness of about 0.02 mu m on the surface of the workpiece, arranging the workpiece and the shielding component on a plating hanger, wherein a gap exists between the shielding component and the region to be shielded of the workpiece, the size of the gap is 2.5mm, immersing the workpiece and the shielding component into a plating bath again, and placing the workpiece and the shielding component on the plating hanger, wherein the current frequency is 100Hz, the forward-reverse current working time ratio is 10The surfaces of the workpiece and the shielding component are approximately parallel to the surface of the anode of the electroplating bath, bidirectional pulse square wave current is used as electroplating current, and the pulse current density is set to be 0.1A/dm²Electroplating at current frequency of 100Hz, forward/reverse current working time ratio of 10:1 and current duty ratio of 20%, wherein the electroplating time is 5 min, and cleaning and baking to obtain the final product.

Comparative example 3:

The operation is as follows: connecting a workpiece to be locally plated with a gold layer to a cathode, immersing the workpiece to be locally plated with the gold layer into an electroplating bath provided with an anode and an electroplating solution, using direct current of 0.6 ampere as the electroplating current, pre-electroplating a gold layer with the thickness of about 0.02 mu m on the surface of the workpiece, arranging an electrically insulated shielding part in a region to be shielded of the workpiece oppositely, arranging the workpiece and the shielding part on an electroplating hanger, wherein a gap exists between the shielding part and the region to be shielded of the workpiece, the size of the gap is 1.9mm, immersing the workpiece and the shielding part into the electroplating bath again, the plate surfaces of the workpiece and the shielding part are approximately parallel to the plate surface of the anode of the electroplating bath, electroplating by using the direct current of 0.6 ampere as the electroplating current, and carrying out electroplating for 5 minutes to obtain a final product after cleaning and baking.

Example 3: hardness test

The gold-plated workpieces of examples 1-2 and comparative example 3 were measured for hardness at five random points in the non-shielded area using a microhardness tester according to the GB/T3398.2-2008 standard, and the results are shown in Table 1.

Table 1: hardness test results

Sample (I)	Average hardness value (Rockwell hardness)
		Example 1	103.0
Example 2	102.2
		Comparative example 3	63.1

And (4) conclusion: compared with direct current, the hardness of the gold-plated layer can be effectively improved by taking bidirectional pulse square wave current as electroplating current.

Example 4: thickness detection

The gold-plated workpieces prepared in examples 1 to 2 and comparative examples 1 to 3 were measured for the thickness of the gold plating layer in the shielding region and the non-shielding region, and the results are shown in table 2.

Table 2: thickness detection

And (4) conclusion: when the gap between the shielding part and the to-be-shielded area of the workpiece is 1.0-1.9mm, the thickness of the shielded area can be obviously reduced, and the transition between the non-shielded area and the shielded area is natural without the phenomena of white exposure, heterochrosis and the like.

Example 5: performance testing

The following performance tests were performed on the gold-plated workpieces prepared in examples 1 to 2 and comparative examples 1 to 3, respectively, for the gold-plated layers in the shielding region and the non-shielding region, and the results are shown in tables 3 to 4.

1. Cohesion test

The gold-plated workpieces prepared in examples 1-2 and comparative examples 1-3 were respectively scribed with 100 cells on the surface, the spacing between the cells was 1.0mm, 11 cells each having a length of about 20mm were scribed in the same direction, 11 cells each having a length of about 20mm were scribed at the center position of 90 degrees crossing each other, the center position of the cut tape was carefully placed on the scribed cells in the horizontal direction to cover the cells completely, and the cut tape was wiped with an eraser to make the tape contact the cells completely and prevent the occurrence of wrinkles and bubbles. Standing for 30-90 seconds after the adhesive tape is stuck; the adhesive tape is quickly pulled up from a single side of the adhesive tape in the horizontal direction of 180 degrees, and the falling area is less than 15 percent, which is qualified.

2. Abrasion resistance test

The electroplated product was rubbed using a 7-IBB RCA abrader from Noman instruments and Equipment, USA, under the action of 175 grams, and the number of revolutions of the rubber wheel was recorded when the electroplated product was exposed to the base material, and it was found that the rubber wheel was qualified when it was more than 500 revolutions.

3. Salt spray test

Placing the electroplated product in a salt spray box, spraying sodium chloride salt water with the concentration of 5 weight percent at 35 ℃ to observe the electroplated product, and recording the time for the surface of the electroplated product to have white spots, bubbling of a transition layer or rusting, wherein the time is generally more than 48 hours and is qualified.

4. Cold and hot shock

And (3) placing the electroplated product in a cold and hot impact test box, reducing the test temperature to minus 40 ℃, placing for 2 hours, then increasing the test temperature to 85 ℃ within 3 minutes, placing for 2 hours, repeating the operation for 5 times, placing the electroplated product in a room temperature environment, and observing whether cracks or peeling appear on the surface of the electroplated product.

Table 3: performance test results for unshielded regions

Table 3: results of shielded area Performance test

And (4) conclusion:

(1) compared with direct current, the adoption of bidirectional pulse square wave current as electroplating current can greatly improve the binding force, wear resistance, salt spray resistance and cold and hot shock resistance of the electroplated gold layer.

(2) When the gap between the shielding part and the region to be shielded of the workpiece is 0.5mm, the binding force, the wear resistance, the salt spray resistance and the cold and hot impact resistance of the electroplating gold layer in the shielding region are slightly poor.

On the other hand, the invention also provides a local electroplating device which comprises an anode, a cathode, an electroplating bath, a detachable shielding component and an adjustable gap with a workpiece to be electroplated, wherein the shielding component is made of an electric insulating material, is positioned at the opposite position of the surface of the area to be shielded of the cathode, and has a gap with the surface of the area to be shielded of the cathode.

The above detailed description of a method, apparatus and product for localized electrogilding with reference to the embodiments is illustrative and not restrictive, and several embodiments may be enumerated in accordance with the limitations, such that variations and modifications may be effected without departing from the spirit of the present invention. Those skilled in the art can modify the process parameters appropriately to achieve the desired results with reference to the disclosure herein. It is expressly intended that all such similar substitutes and modifications which would be obvious to those skilled in the art are deemed to be included within the invention.

Claims

1. A method for local gold electroplating is characterized by comprising the following steps:

s10, connecting the workpiece to be locally plated with the gold layer to a cathode, immersing the workpiece into an electroplating bath provided with an anode and electroplating solution, and electroplating a gold layer with the thickness of 0.01-0.03 mu m on the surface of the workpiece in advance;

and S20, arranging an electrically insulated shielding component in the region to be shielded of the workpiece oppositely, and then carrying out electroplating, wherein a gap exists between the shielding component and the region to be shielded of the workpiece.

2. The method of claim 1, wherein the gap is 1.0-1.9mm in size.

3. The method of any of claims 1-2, wherein the shielding member is a hydrophobic material.

4. The method of any one of claims 1-2, wherein the electroplating current in steps S10 and/or S20 is a bi-directional pulsed square wave current.

5. A process according to any one of claims 1 to 2 wherein the plating bath in steps S10 and/or S20 contains a water soluble gold salt in an amount of 2.5g/L calculated as gold ion concentration and a thallium compound in an amount of 0.05 to 0.1g/L calculated as thallium ion concentration.

6. The method of claim 4, wherein the parameters of the bi-directional pulsed square wave current are: the pulse current density is 0.1-0.2A/dm²The current frequency is 50-1000Hz, the working time ratio of forward current to reverse current is 10:1, and the duty ratio is 20-30%; the parameters of the bidirectional pulse square wave current in the steps S10 and S20 are the same or different.

7. The method of any one of claims 1-2, wherein the anode is a platinum titanium mesh.

8. The method according to any one of claims 1 to 2, wherein the time of the electroplating in step S20 is 5 to 10 minutes.

9. A product prepared according to the method of any one of claims 1-8.

10. A local electroplating device comprises an anode, a cathode and an electroplating bath, and is characterized by being further provided with a detachable shielding component and a gap between the shielding component and a workpiece to be electroplated, wherein the shielding component is made of an electric insulating material, is positioned at the opposite position of the surface of a region to be shielded of the cathode, and has a gap with the surface of the region to be shielded of the cathode.