阅读说明：本技术 电镀铜溶液添加剂、电镀铜溶液以及电镀方法 (Copper electroplating solution additive, copper electroplating solution and electroplating method ) 是由 徐群杰 周苗淼 孟雅超 张雨 沈喜训 于 2021-06-23 设计创作，主要内容包括：本发明属于电镀技术领域,提供了电镀铜溶液添加剂、电镀铜溶液以及电镀方法,电镀铜溶液添加剂包括加速剂1-10份、抑制剂150-300份以及整平剂1-20份,加速剂为聚二硫二丙烷磺酸钠,抑制剂为聚乙二醇-6000、聚乙二醇-8000、聚乙二醇-10000中的任意一种或几种的任意比例组合,整平剂为5-氨基-1,3,4-噻二唑-2-硫醇,该整平剂价格低廉、毒性小且稳定。电镀铜溶液含有本发明的电镀铜溶液添加剂,电镀方法使用了该电镀铜溶液,所以电镀效果较好,从而使得盲孔镀层深镀能力较好,填孔率较高、凹陷度低、填孔效果好,铜层表面平整性好,无明显铜瘤产生,形成超填充,无空洞,无夹缝,表面光亮,可以有效防止因为盲孔空洞传输不稳定等缺点,进一步提高电子产品的可靠性。(The invention belongs to the technical field of electroplating, and provides an additive of an electroplating copper solution, the electroplating copper solution and an electroplating method, wherein the additive of the electroplating copper solution comprises 1-10 parts of an accelerator, 150-300 parts of an inhibitor and 1-20 parts of a leveling agent, the accelerator is poly-dithio-dipropyl sodium sulfonate, the inhibitor is any one or combination of more of polyethylene glycol-6000, polyethylene glycol-8000 and polyethylene glycol-10000 in any proportion, and the leveling agent is 5-amino-1, 3, 4-thiadiazole-2-thiol. The electroplating copper solution contains the additive of the electroplating copper solution, and the electroplating method uses the electroplating copper solution, so the electroplating effect is better, the plating depth of the blind hole plating layer is better, the hole filling rate is higher, the depression degree is low, the hole filling effect is good, the surface smoothness of the copper layer is good, no obvious copper nodules are generated, super filling is formed, no cavity is formed, no crack is formed, the surface is bright, the defects of unstable cavity transmission of the blind hole and the like can be effectively prevented, and the reliability of an electronic product is further improved.)

1. The additive for the electrolytic copper plating solution is characterized by comprising the following components in parts by mass:

1-10 parts of accelerator, 150-300 parts of inhibitor and 1-20 parts of leveling agent,

wherein the accelerator is sodium polydithio-dipropyl sulfonate,

the inhibitor is any one or combination of several of polyethylene glycol-6000, polyethylene glycol-8000 and polyethylene glycol-10000 in any proportion,

the leveling agent is 5-amino-1, 3, 4-thiadiazole-2-thiol.

2. The additive for electrolytic copper plating solution according to claim 1, characterized in that:

wherein the concentration of the accelerator is 1mg/L-10 mg/L.

3. The additive for electrolytic copper plating solution according to claim 1, characterized in that:

wherein the concentration of the inhibitor is 150mg/L-300 mg/L.

4. The additive for electrolytic copper plating solution according to claim 1, characterized in that:

wherein the concentration of the leveling agent is 1mg/L-20 mg/L.

5. An electrolytic copper plating solution comprising the additive for electrolytic copper plating solutions according to any one of claims 1 to 4.

6. An electroplating method, comprising the steps of:

step D1, soaking the test board with the punched blind holes in an ethanol solution for a period of time, and then washing the test board;

step D2, putting the test board into 10 wt% sulfuric acid solution for activation treatment for a period of time to obtain an activated test board;

step D3, pouring the copper electroplating solution into an electroplating bath, putting the activated test board into the electroplating bath to be used as a cathode, and soaking for a period of time;

step D4, placing the soluble phosphor copper plate wrapped by the filter bag into the electroplating bath as an anode, electrifying direct current to the cathode and the anode for a period of time, completing electroplating of the test board,

wherein the electrolytic copper plating solution is the electrolytic copper plating solution according to claim 5.

7. The plating method according to claim 5, characterized in that:

the aperture of the blind hole of the test board is 120 μm, and the hole depth is 75 μm.

8. The plating method according to claim 5, characterized in that:

wherein the temperature of the electrolytic copper plating solution is maintained at 15 ℃ to 35 ℃.

9. The plating method according to claim 5, characterized in that:

wherein the current density of the direct current passing through the cathode and the anode is 1A/dm²-3A/dm²。

10. The plating method according to claim 5, characterized in that:

wherein the electrifying time of the direct current is 30-120 min.

Technical Field

The invention belongs to the technical field of electroplating, and particularly relates to an additive for an electroplating copper solution, the electroplating copper solution and an electroplating method.

Background

With the development of the electronic information industry and the progress of electronic devices, the development of electroplating process is not separated from the high-end electronic manufacturing industry. In the manufacturing industry chain of electronic circuits and electronic components, the electroplated copper plays a key role in the modern electronic industry due to its advantages of high reliability and productivity, low cost, and satisfying the electrical and thermal transmission characteristics. Therefore, gap filling by electroplating copper has become an indispensable technology, and is widely applied to metallization of High Density Interconnect (HDI) in integrated circuits and blind hole filling in Printed Circuit Boards (PCBs).

The copper electrodeposition is done by bottom-up filling in the hole to ensure void-free filling. This means that the bottom of the hole has the highest copper deposition rate during electroplating. In fact, the current density at the bottom of the hole is small and the current density at the orifice is large due to the non-uniform distribution of the primary and secondary currents. The non-uniform local current density distribution results in less copper deposition at the bottom of the hole during electrodeposition and more copper deposition at the orifice, gradually closing the orifice, creating a void or void in the middle of the hole. In order to meet the requirement of void-free filling, the additive is an indispensable component in the electrolytic copper plating. The bottom-up fill behavior is caused by additive synergistic interactions rather than by individual factors or components. The effect of the additives in the plating bath is not a simple superposition of the effects of each single-component additive, but rather a result of complex synergistic or anti-competitive effects therein. The synergy between the additives results mainly from their adsorption and migration properties under chloride ions and from the competition between accelerators, inhibitors and levelers. Only under the specific additive combination and the optimized concentration, the completely filled electroplated copper can be realized, and the quality of the plating layer can be better ensured, so that the interconnection between layers is realized. Moreover, the additive can also improve the current efficiency, adjust the deposition rate of copper in high and low current density areas, refine crystal grains and improve the crystal orientation, thereby obtaining a more uniform and smooth plating layer.

The blind hole electro-coppering filling usually adopts a high-copper low-acid system, and the electro-coppering solution contains an inorganic additive and three organic additives which are divided into an accelerator, an inhibitor and a leveling agent. Halogen ions are indispensable components in the acidic copper plating system plating solution, and are usually mainly chloride ions, which are mainly present in the electrolytic copper plating solution in the form of sodium chloride or hydrochloric acid. Although the content of the chlorine ion in the copper electroplating solution is low, the concentration of the chlorine ion is controlled between 30mg/L and 70mg/L, but the chlorine ion plays a great role. Cl^-Besides the functions of improving the anode activity and promoting the normal dissolution of the anode, the copper powder generated by incomplete anode dissolution can be reduced, the brightness and leveling capability of the coating are improved, and the coating quality is improved.

Although the additives are used in very small quantities in the plating bath, typically only a few to tens of micrograms per liter of accelerator and leveler, and a few hundred micrograms per liter of suppressor, this small concentration variation will eventually lead to a large difference in filling performance. For accelerators, small molecule aliphatic sulfur-containing organics are typical. In the electroplating process, the accelerator is beneficial to the formation of crystal nuclei, plays a role of refining crystal grains, enables the crystal nuclei to be densely distributed, promotes the copper plating layer to become smooth, and can enhance the copper deposition rate at the bottom of the hole. But when used alone, the copper alloy can not play a role in acceleration, but can prevent the deposition of metal copper. The inhibitor can be adsorbed on the surface of the cathode, finally the effect of inhibiting the deposition of metal copper is achieved, the electroplated copper can be uniformly and continuously deposited, and the inhibitor can also serve as a wetting agent to reduce the surface tension of an interface and enable the electroplated copper solution to enter the hole more easily so as to increase the mass transfer effect. For levelers, which are generally positively charged and can adsorb at the openings of the high electron density regions, i.e., pores, to inhibit copper deposition, are critical to achieving superfilling or bottom-up deposition. Therefore, designing a leveler that can achieve excellent filling performance is a critical issue. Leveling agents that have been developed to date are mainly based on organic dye-based leveling agents having a quaternary ammonium cation and a halogen ion. Although such leveling agents can achieve excellent filling effects under their specific conditions, they are not resistant to high temperatures and are easily decomposed, which is disadvantageous for large-scale industrial production. At the same time, such levelers still present some quality problems and environmental pollution problems. Leveling agents currently used in industry are mostly macromolecular compounds, most of which are synthesized organic matters or mixtures of a plurality of organic matters, so that the cost is high, the synthesis process is complex, the yield is low, and the toxicity and the pollution are high.

Disclosure of Invention

The present invention has been made to solve the above problems, and an object of the present invention is to provide an additive for an electrolytic copper plating solution, and an electrolytic copper plating method.

The invention provides an additive of an electrolytic copper plating solution, which is characterized by comprising the following components in percentage by mass: 1-10 parts of accelerator, 150-300 parts of inhibitor and 1-20 parts of leveling agent, wherein the accelerator is poly-disulfide dipropyl sodium sulfonate, the inhibitor is any one or combination of polyethylene glycol-6000, polyethylene glycol-8000 and polyethylene glycol-10000 in any proportion, and the leveling agent is 5-amino-1, 3, 4-thiadiazole-2-thiol.

The additive for electrolytic copper plating solutions provided by the present invention may also have the following characteristics: wherein the concentration of the accelerator is 1mg/L-10 mg/L.

The additive for electrolytic copper plating solutions provided by the present invention may also have the following characteristics: wherein the concentration of the inhibitor is 150mg/L-300 mg/L.

The additive for electrolytic copper plating solutions provided by the present invention may also have the following characteristics: wherein the concentration of the leveling agent is 1mg/L-20 mg/L.

The present invention provides an electrolytic copper plating solution having such a feature that it comprises the additive for an electrolytic copper plating solution as defined in any one of the above.

The present invention provides an electroplating method having such a feature that it comprises the steps of: step D1, soaking the test board with the punched blind holes in an ethanol solution for a period of time, and then washing the test board; step D2, putting the test board into 10 wt% sulfuric acid solution for activation treatment for a period of time to obtain an activated test board; step D3, pouring the copper electroplating solution into the electroplating bath, putting the activated test board into the electroplating bath as a cathode, and soaking for a period of time; and D4, putting the soluble phosphor copper plate wrapped by the filter bag into an electroplating bath as an anode, and electrifying direct current to the cathode and the anode for a period of time to complete the electroplating of the test board, wherein the electroplating copper solution is the electroplating copper solution.

The plating method provided by the present invention may further have the following features: the blind holes of the test board have a hole diameter of 120 μm and a hole depth of 75 μm.

The plating method provided by the present invention may further have the following features: wherein the temperature of the electrolytic copper plating solution is maintained at 15 ℃ to 35 ℃.

The plating method provided by the present invention may further have the following features: wherein the current density of the direct current passing through the cathode and the anode is 1A/dm²-3A/dm²。

The plating method provided by the present invention may further have the following features: wherein the electrifying time of the direct current is 30 min-120 min.

Action and Effect of the invention

According to the additive for the electrolytic copper plating solution, the electrolytic copper plating solution and the electroplating method, the additive for the electrolytic copper plating solution comprises 1-10 parts of an accelerator, 150-300 parts of a suppressor and 1-20 parts of a leveling agent, wherein the accelerator is poly-disulfide dipropyl sodium sulfonate, the suppressor is any one or combination of more of polyethylene glycol-6000, polyethylene glycol-8000 and polyethylene glycol-10000 in any proportion, and the leveling agent is 5-amino-1, 3, 4-thiadiazole-2-thiol, so that the leveling agent is low in price, low in toxicity and stable. Because the electroplating copper solution contains the electroplating copper solution additive, the electroplating method provided by the invention uses the electroplating copper solution, so that the electroplating effect is better, the plating depth of the blind hole plating layer is better, the hole filling rate is higher, the depression is low, the hole filling effect is good, the surface smoothness of the copper layer is good, no obvious copper nodules are generated, super filling is formed, no cavity is generated, no crack is generated, the surface is bright, the defects of unstable transmission of the blind hole cavity and the like can be effectively prevented, and the reliability of electronic products is further improved.

Drawings

FIG. 1 is a structural formula of leveling agent 5-amino-1, 3, 4-thiadiazole-2-thiol in an example of the present invention;

FIG. 2 is a diagram illustrating an effect of attaching an insulating tape on the back surface of a stainless steel plate according to an embodiment of the present invention;

FIG. 3 is a diagram illustrating the effect of attaching a PCB to the front surface of a stainless steel plate with a conductive adhesive according to an embodiment of the present invention;

FIG. 4 is a diagram illustrating the effect of attaching an insulating tape to the front surface of a stainless steel plate according to an embodiment of the present invention;

FIG. 5 is an exemplary diagram of the effect of the blind holes in the PCB after electroplating, after 200 times magnification, according to an embodiment of the present invention;

FIG. 6 is a schematic view of a PCB with blind vias enlarged 200 times when not plated according to a comparative example of the present invention;

FIG. 7 is an exemplary diagram of the effect of the blind via in the PCB after plating according to the comparative example of the present invention after enlarging by 200 times.

Detailed Description

In order to make the technical means, the creation features, the achievement objects and the effects of the present invention easy to understand, the following embodiments are specifically described with reference to the accompanying drawings.

< example >

This example describes the additive of the electrolytic copper plating solution, the electrolytic copper plating solution and the plating method in detail.

The electrolytic copper plating solution provided in this example includes a base solution and an additive for the electrolytic copper plating solution.

The preparation steps of the base liquid are as follows:

step S1, weighing 220g of blue copperas by an analytical balance and placing the blue copperas in a beaker;

step S2, adding part of deionized water, stirring and dissolving;

step S3, 29.9ml of sulfuric acid with the concentration of 55g/L is measured and slowly injected into the copper sulfate solution, and stirring and diluting are carried out;

step S4, adding deionized water into the copper sulfate solution injected with sulfuric acid until the volume of the solution reaches 1L;

and step S5, cooling the solution to room temperature to obtain a base solution.

The preparation steps of the additive are as follows:

step A1, weighing 0.1g of sodium polydithio-dipropyl sulfonate (SPS) by using an analytical balance, dissolving in a 1000ml volumetric flask, and preparing SPS solution with the concentration of 0.1g/L as an accelerator;

step A2, weighing 10g of polyethylene glycol-6000 by using an analytical balance, dissolving in a 1000ml volumetric flask, and preparing 10g/L PEG solution as an inhibitor;

step A3, weighing 0.1g of 5-amino-1, 3, 4-thiadiazole-2-thiol by using an analytical balance, dissolving in a 1000ml volumetric flask, and preparing a 5-amino-1, 3, 4-thiadiazole-2-thiol solution with the concentration of 0.1g/L as a leveling agent (the structural formula is shown in figure 1);

and step A4, measuring 10.5ml of concentrated hydrochloric acid by using a pipette, dissolving the concentrated hydrochloric acid in a 250ml volumetric flask, and preparing a hydrochloric acid solution with the concentration of 0.5 mol/L.

The additive prepared in this example was added to the base solution prepared in this example to obtain an electrolytic copper plating solution.

The preparation of the cathode test plate used in this example included the following steps:

step C1, using a stainless steel plate with the size of 70mm multiplied by 50mm multiplied by 0.3mm as a substrate, punching a hole in the center of the uppermost end of the stainless steel plate and binding a copper wire, connecting a clip at the negative end of a power supply to the copper wire during electroplating, and preventing electroplating solution from splashing on the power supply clip to electroplate the copper;

step C2, washing the stainless steel plate with deionized water, drying the stainless steel plate by blowing, and sticking the back of the stainless steel plate with 3M insulating glue; (see FIG. 2)

C3, sticking the cut PCB with a certain size to the center of the front side of the stainless steel plate substrate by using a conductive adhesive, and firmly sticking the PCB with the stainless steel plate substrate by force to ensure that the conductive adhesive is in good contact with the PCB and the stainless steel plate substrate; (see FIG. 3)

And step C4, sticking the other places (including the place where the conductive adhesive is stuck) with 3M insulating glue except the area where the PCB to be plated is exposed, and obtaining the cathode test board (see figure 4).

The electroplating method related in the embodiment comprises the following steps:

d1, soaking the test board with the punched blind holes in an ethanol solution for a period of time, wiping the test board with a cotton ball dipped with ethanol to remove organic pollutants on the surface of the test board, and washing with deionized water to ensure that insoluble matters are removed and washed cleanly;

step D2, putting the test board into 10 wt% sulfuric acid solution, uniformly shaking for two minutes to remove the surface oxide of the copper layer, and activating to obtain an activated test board;

step D3, pouring the prepared copper electroplating solution into an electroplating bath, putting the activated test board into the electroplating bath as a cathode, starting a bubbling device and a stirring table, and stirring the copper electroplating solution to fully wet the test board and the blind holes, wherein the soaking time is 10 min;

d4, coating filter bag on the anode to obtain soluble phosphor-copper plate as anode plate, controlling the temperature of the plating solution at room temperature, and applying current to the cathode and anode at a density of 1.5A/dm²Electrifying for 70min to complete the electroplating of the test board.

FIG. 5 is an exemplary diagram of the effect of the blind holes in the PCB after electroplating according to the embodiment after being magnified by 200 times.

As can be seen from FIG. 5, the electroplating in the solution after the accelerator, the inhibitor and the novel leveling agent are added can realize the complete filling from bottom to top without any holes and gaps, thereby effectively preventing the defects of unstable transmission and the like of blind holes and further improving the reliability of electronic products.

< comparative example >

The preparation steps of the electrolytic copper plating solution provided by the comparative example are as follows:

step S1, weighing 220g of blue copperas by an analytical balance and placing the blue copperas in a beaker;

step S2, adding part of deionized water, stirring and dissolving;

step S3, 29.9ml of sulfuric acid with the concentration of 55g/L is measured and slowly injected into the copper sulfate solution, and stirring and diluting are carried out;

step S4, adding deionized water into the copper sulfate solution injected with sulfuric acid until the volume of the solution reaches 1L;

and step S5, cooling the solution to room temperature to obtain the electrolytic copper plating solution.

The preparation of the cathode test panel used in this comparative example included the following steps:

step C1, using a stainless steel plate with the size of 70mm multiplied by 50mm multiplied by 0.3mm as a substrate, punching a hole in the center of the uppermost end of the stainless steel plate and binding a copper wire, connecting a clip at the negative end of a power supply to the copper wire during electroplating, and preventing electroplating solution from splashing on the power supply clip to electroplate the copper;

step C2, washing the stainless steel plate with deionized water, drying the stainless steel plate by blowing, and sticking the back of the stainless steel plate with 3M insulating glue;

c3, sticking the cut PCB with a certain size to the center of the front side of the stainless steel plate substrate by using a conductive adhesive, and firmly sticking the PCB with the stainless steel plate substrate by force to ensure that the conductive adhesive is in good contact with the PCB and the stainless steel plate substrate;

and C4, sticking other places (including the place where the conductive adhesive is stuck) with 3M insulating glue except the area where the PCB to be plated is exposed to obtain the cathode test board.

The plating method related to this comparative example includes the steps of:

d1, soaking the test board with the punched blind holes in an ethanol solution for a period of time, wiping the test board with a cotton ball dipped with ethanol to remove organic pollutants on the surface of the test board, and washing with deionized water to ensure that insoluble matters are removed and washed cleanly;

step D2, putting the test board into 10 wt% sulfuric acid solution, uniformly shaking for two minutes to remove the surface oxide of the copper layer, and activating to obtain an activated test board;

step D3, pouring the prepared copper electroplating solution into an electroplating bath, putting the activated test board into the electroplating bath as a cathode, starting a bubbling device and a stirring table, and stirring the copper electroplating solution to fully wet the test board and the blind holes, wherein the soaking time is 10 min;

d4, coating filter bag on the anode to obtain soluble phosphor-copper plate as anode plate, controlling the temperature of the plating solution at room temperature, and applying current to the cathode and anode at a density of 1.5A/dm²Electrifying for 70min to complete the electroplating of the test board.

FIG. 6 is a schematic view of a blind via in a PCB board when not plated in this comparative example after being enlarged by 200 times, and FIG. 7 is an exemplary view of the effect of a blind via in a PCB board after being plated in a base plating solution in this comparative example after being enlarged by 200 times, and it can be seen that a large void appears in the middle of a blind via in a printed circuit board plated in a solution without an additive added thereto.

Effects and effects of the embodiments

According to the additive for the electrolytic copper plating solution, the electrolytic copper plating solution and the electroplating method, the additive for the electrolytic copper plating solution comprises 1-10 parts of an accelerator, 150-300 parts of a suppressor and 1-20 parts of a leveling agent, wherein the accelerator is poly-disulfide dipropyl sodium sulfonate, the suppressor is any one or combination of more of polyethylene glycol-6000, polyethylene glycol-8000 and polyethylene glycol-10000 in any proportion, and the leveling agent is 5-amino-1, 3, 4-thiadiazole-2-thiol, so that the leveling agent is low in price, low in toxicity and stable. Because the electroplating copper solution contains the electroplating copper solution additive, the electroplating method provided by the invention uses the electroplating copper solution, so that the electroplating effect is better, the plating depth of the blind hole plating layer is better, the hole filling rate is higher, the depression is low, the hole filling effect is good, the surface smoothness of the copper layer is good, no obvious copper nodules are generated, super filling is formed, no cavity is generated, no crack is generated, the surface is bright, the defects of unstable transmission of the blind hole cavity and the like can be effectively prevented, and the reliability of electronic products is further improved.

The above embodiments are preferred examples of the present invention, and are not intended to limit the scope of the present invention.