WO2020042613A1 - Electroplating solution and electroplating method employing same - Google Patents

Abstract

The present application provides an electroplating solution and an electroplating method employing the same. The electroplating solution comprises the following components by weight/volume concentration: 0.3-25 g/L of tetralvanadium, 4-10 g/L of ferrous iron, 0.3-5 g/L of ferric iron, 100-250 g/L of copper sulfate, 50-210 g/L of sulfuric acid, and 30-150 mg/L of a chloride.

Description

Electroplating solution and electroplating method Technical field

The present application belongs to the technical field of electroplating copper, and relates to a plating solution and a plating method thereof.

Background technique

With the development of science and technology, electronic products are becoming more and more intelligent and miniaturized. This trend continues to promote the improvement of circuit board manufacturing processes; and eventually leads to the emergence of high-density interconnect circuit boards (HDI). Such a circuit board has a small pad diameter, a small wiring width, a small line spacing, and a large number of layers. Therefore, there are a large number of through holes or blind holes that provide pathways between different layers, and the apertures are small; this brings great challenges to the process of metallizing the holes and establishing the pathways between the layers. The drilling process, filling materials, and The subsequent process steps of the printed circuit board will affect the choice of the hole filling process.

In order to prevent the welding material from passing on the plate, achieve high integration and improve electrical characteristics, it is necessary to seal the through holes and blind holes. For multi-layer circuit boards, for example, inclusions (air, solvents, and the like) may appear in the holes during the application of the next structural layer, which inclusions cause bumps and subsequently cracks in subsequent layers when thermal strain occurs later.

Therefore, the main conditions for filling materials for holes are: solvent-free, good adhesion properties on sleeves and solder masks, for subsequent steps (for example, electroplated metallization with nickel, gold or tin) Stability of process aids and durability in hot air leveling.

CN104131319A discloses a plating solution for filling holes on the surface of a plate and a plating method thereof. The plating solution contains 0.1 to 200 g / L tetravalent vanadium and 0.2 to 15 g / L pentavalent vanadium. In the electroplating solution of the present invention, the added tetravalent vanadium and pentavalent vanadium can constitute a quasi-reversible redox system, and the reduction of pentavalent vanadium takes precedence over the reduction of divalent copper in the redox system. Compared with the ferrous / trivalent iron system in the related technology, the charge number of pentavalent vanadium is much higher than that of trivalent iron ions, which makes the radius of pentavalent vanadium hydrates larger than that of trivalent iron hydrates. Highly oxidized metal ions due to concentration polarization are also difficult to replenish in the form of electron transfer, so a better hole filling effect can be obtained. However, the pentavalent vanadium contained in the plating solution of the present invention is highly toxic.

Summary of the Invention

The following is an overview of the topics detailed in this article. This summary is not intended to limit the scope of protection of the claims.

One of the objectives of this application is to provide a plating solution, which is safe and environmentally friendly, and has a high deep plating ability when plating through holes and blind holes.

To achieve this, the following technical solutions are used in this application:

A plating solution, based on mass-volume concentration, contains the following components:

In the present application, in a sulfuric acid and copper sulfate solution, a tetravalent vanadium oxidizable copper elementary substance is copper ions to generate trivalent vanadium. The trivalent vanadium is oxidized by the trivalent iron to become the tetravalent vanadium, and the trivalent iron becomes the divalent iron. Therefore, a sufficient amount of divalent iron in the plating solution can prevent the occurrence of the more toxic pentavalent vanadium, and make the tetravalent vanadium as the main component of copper dissolution. Iron mainly exists in the form of divalent iron. The mass-volume concentration of tetravalent vanadium, divalent iron, trivalent iron, sulfuric acid, copper sulfate, and chlorides enables the combination of vanadium and iron systems to exert higher deep plating capabilities.

As an alternative, the plating solution of the present application, based on mass-volume concentration, includes the following components:

Tetravalent vanadium 0.3 to 25 g / L, for example, the mass-volume concentration of tetravalent vanadium is 0.3 g / L, 0.5 g / L, 0.8 g / L, 1 g / L, 2 g / L, 3 g / L, 4 g / L, 5g / L, 6g / L, 7g / L, 8g / L, 9g / L, 10g / L, 11g / L, 12g / L, 13g / L, 14g / L, 15g / L, 16g / L, 17g / L, 18g / L, 19g / L, 20g / L, 21g / L, 22g / L, 23g / L, 24g / L, 25g / L.

The divalent iron is 4 to 10 g / L. For example, the mass-volume concentration of the divalent iron is 4 g / L, 5 g / L, 6 g / L, 7 g / L, 8 g / L, 9 g / L, and 10 g / L.

Ferric iron 0.3 ～ 5g / L, for example, the mass-volume concentration of ferric iron is 0.3g / L, 0.4g / L, 0.5g / L, 0.6g / L, 0.7g / L, 0.8g / L, 0.9 g / L, 1g / L, 1.5g / L, 2g / L, 2.5g / L, 3g / L, 4g / L, 5g / L.

Copper sulfate 100 ～ 250g / L, for example, the mass-volume concentration of copper sulfate is 100g / L, 110g / L, 120g / L, 130g / L, 140g / L, 150g / L, 160g / L, 170g / L, 180g / L, 190g / L, 200g / L, 210g / L, 220g / L, 230g / L, 240g / L, 250g / L.

Sulfuric acid 50 ～ 210g / L, for example, the mass-volume concentration of sulfuric acid is 50g / L, 60g / L, 70g / L, 80g / L, 90g / L, 100g / L, 110g / L, 120g / L, 130g / L , 140g / L, 150g / L, 160g / L, 170g / L, 180g / L, 190g / L, 200g / L, 210g / L.

Chloride 30 ～ 150mg / L, for example, the mass-volume concentration of chloride is 30, 40, 50g / L, 60g / L, 70g / L, 80g / L, 90g / L, 100g / L, 110g / L, 120g / L, 130g / L, 140g / L, 150g / L.

In this application, the mass-volume concentration of the tetravalent vanadium is 0.5 to 10 g / L, for example, the mass-volume concentration of the tetravalent vanadium is 0.5 g / L, 0.6 g / L, 0.7 g / L, 0.8 g / L, 0.9g / L, 1g / L, 1.5g / L, 2g / L, 2.5g / L, 3g / L, 3.5g / L, 4g / L, 4.5g / L, 5g / L, 5.5g / L, 6g / L, 6.5g / L, 7g / L, 7.5g / L, 8g / L, 8.5g / L, 9g / L, 9.5g / L, 10g / L.

In the present application, the mass-volume concentration of the trivalent iron is 0.3 to 2 g / L, for example, the mass-volume concentration of the trivalent iron is 0.3 g / L, 0.4 g / L, 0.5 g / L, 1 g / L, 1.1g / L, 1.2g / L, 1.3g / L, 1.4g / L, 1.5g / L, 1.6g / L, 1.7g / L, 1.8g / L, 1.9g / L, 2g / L .

In the present application, the tetravalent vanadium is VOSO ₄ and / or V ₂ O ₄ .

The plating solution of the present application further includes additives, which include additive A with a mass concentration of 0.2 to 30 ppm and additive B with a mass-volume concentration of 0.1 to 3 g / L; for example, the mass concentration of additive A is 0.2 ppm, 1 ppm, and 2 ppm. , 3ppm, 4ppm, 5ppm, 6ppm, 7ppm, 8ppm, 9ppm, 10ppm, 15ppm, 20ppm, 25ppm, 30ppm; Mass-volume concentration of additive B is 0.1g / L, 0.5g / L, 1g / L, 1.5g / L, 2g / L, 2.5g / L, 3g / L.

The additive A is sodium polydithiodipropane sulfonate, sodium 3-mercaptopropane sulfonate, sodium N, N-dimethyldithiocarbonylpropane sulfonate, isothiourea propane sulfonate internal salt, and 3- ( One or a mixture of at least two of benzithiazole-2-mercapto) -propane sulfonate.

Optionally, the additive B is a mixture of polyoxypropylene polyoxyethylene ether and polyethylene glycol monomethyl ether.

The second purpose of this application is to provide a plating method, which is simple and fast in operation. It can complete plating in 20 to 120 minutes. The thickness of the plating on the board is evenly distributed. The thickness of the board is thin. For the production efficiency of a plate, in the electroplating method of the present application, a plate member with a hole on the surface is immersed in the electroplating solution, and the plate member is used as a cathode to be electroplated.

In this application, the forward current density of the current is 1 to 10 A / dm ² , and the reverse current density of the current is 1 to 30 A / dm ² ; for example, the forward current density of the current is 1 A / dm ² , 2 A / dm ² , 3A / dm ² , 4A / dm ² , 5A / dm ² , 6A / dm ² , 7A / dm ² , 8A / dm ² , 9A / dm ² , 10A / dm ² , the reverse direction of the energization Current density is 1A / dm ² , 2A / dm ² , 3A / dm ² , 4A / dm ² , 5A / dm ² , 6A / dm ² , 7A / dm ² , 8A / dm ² , 9A / dm ² , 10A / dm ² , 11A / dm ² , 12A / dm ² , 13A / dm ² , 14A / dm ² , 15A / dm ² , 16A / dm ² , 17A / dm ² , 18A / dm ² , 19A / dm ² , 20A / dm ² , 21A / dm ² , 22A / dm ² , 23A / dm ² , 24A / dm ² , 25A / dm ² , 26A / dm ² , 27A / dm ² , 28A / dm ² , 29A / dm ² , 30A / dm ² .

The forward current pulse time is 20-300ms, for example, the forward current pulse time is 20ms, 30ms, 40ms, 50ms, 60ms, 70ms, 80ms, 90ms, 100ms, 150ms, 200ms, 250ms, 300ms; the reverse current The pulse time is 2 to 100 ms. For example, the reverse current pulse time is 2 ms, 5 ms, 10 ms, 20 ms, 30 ms, 40 ms, 50 ms, 60 ms, 70 ms, 80 ms, 90 ms, and 100 ms.

Optionally, the plating time is 20 to 120 minutes, for example, the plating time is 20min, 21min, 22min, 23min, 24min, 25min, 26min, 27min, 28min, 29min, 30min, 31min, 32min, 33min, 34min , 35min, 36min, 37min, 38min, 39min, 40min, 50min, 60min, 70min, 80min, 90min, 100min, 110min, 120min.

The holes of the plate member are through holes and / or blind holes; optionally, the aspect ratio of the hole is (3-6): 1, for example, the aspect ratio of the hole is 3: 1, 4: 1 , 5: 1, 6: 1.

Optionally, the hole diameter of the through hole is 200-400 μm, for example, the hole diameter of the through hole is 200 μm, 210 μm, 220 μm, 230 μm, 240 μm, 250 μm, 260 μm, 270 μm, 280 μm, 290 μm, 300 μm, 310 μm, 320 μm, 330 μm, 340 μm , 350 μm, 360 μm, 370 μm, 380 μm, 390 μm.

Optionally, the pore diameter of the blind hole is 80-100 μm, for example, the pore diameter of the blind hole is 80 μm, 81 μm, 82 μm, 83 μm, 84 μm, 85 μm, 86 μm, 87 μm, 88 μm, 89 μm, 90 μm, 91 μm, 92 μm, 93 μm, 94 μm , 95 μm, 96 μm, 97 μm, 98 μm, 99 μm, 100 μm.

As an optional solution of the present application, the electroplating method immerses a plate-shaped member with through holes and / or blind holes on the surface into the plating solution, and the aspect ratio of the through holes or blind holes is (3 to 6) : 1, electroplating is performed after the plate-shaped member is used as a cathode, wherein the forward current density of the current is 1-10A / dm ² , and the reverse current density of the current is 1-30A / dm ² ; The plating time is 20-40 minutes.

Compared with related technologies, the beneficial effects of this application are:

(1) The electroplating solution of this application is safe, non-toxic and environmentally friendly. The combination of vanadium system and iron system exerts a higher deep plating ability. By adding a small amount of vanadium, a good electroplating effect can be produced. The TP value when plating through holes is greater than 100%, and the middle part of the hole is slightly thick; in the plating process of the high aspect ratio through-hole (3 ~ 6): 1, it also has high deep plating ability.

(2) The electroplating method of this application has simple operation and high speed. Generally, the electroplating can be completed in 20-120 minutes. The thickness of the plating on the surface is thin and no thinning treatment is required. The uniform distribution of the thickness of the plating on the surface improves the circuit board. Productivity.

(3) The electroplating method of the present application reduces the situation of anodic oxygen evolution and reduces plating hole defects caused by the bubbles generated by the anodic oxygen evolution blocking the micro-blind holes.

After reading and understanding the detailed description and drawings, other aspects will become apparent.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a device diagram of an electroplating method of the present application;

FIG. 2 is a schematic view of a cross-sectional structure of a through-hole after plated parts with through-holes are plated;

FIG. 3 (a) is a schematic view of sliced through holes after plating in Example 1 of the present application; FIG.

3 (b) is a schematic view of a sliced through hole after electroplating in Comparative Example 1 of the present application;

FIG. 4 (a) is a schematic view of sliced through-holes after plating in Embodiment 2 of this application; FIG.

4 (b) is a schematic view of a through-hole slice after electroplating in Comparative Example 2 of the present application;

FIG. 5 (a) is a schematic view of sliced through-holes after plating in Embodiment 3 of the present application; FIG.

5 (b) is a schematic view of a through-hole slice after plating in Comparative Example 3 of the present application;

6 is a schematic cross-sectional structural diagram of a micro-blind hole plate after half-filling the blind hole;

FIG. 7 is a schematic diagram of a blind hole slice after plating a half-filled blind hole in Embodiment 4 of the present application; FIG.

FIG. 8 (a) is a schematic diagram of a blind hole slice after plating a half-filled blind hole in Example 5 of the present application; FIG.

FIG. 8 (b) is a schematic diagram of a blind hole slice after plating a half-filled blind hole in Comparative Example 5;

FIG. 9 is a schematic cross-sectional structure diagram of a plated part of a micro-blind hole after the blind hole is plated;

10 is a schematic diagram of a blind hole slice after the blind hole is plated by plating in Embodiment 6 of the present application;

11 is a schematic view of a blind hole slice after the blind hole is plated by plating in Embodiment 7 of the present application;

FIG. 12 is a schematic diagram of the anodic polarization curve of a ruthenium-iridium-coated titanium electrode in an electrolyte solution containing ferrous or (and) tetravalent vanadium according to Example 8 of the present application.

The reference signs are as follows:

1-cathode; 2-anode; 3-current source; 4-pump; 5-copper particles; 6-dissolving copper tank.

detailed description

The technical solutions of the present application will be further described below with reference to the accompanying drawings 1-12 and specific embodiments.

Unless otherwise specified, various raw materials of the present application may be commercially available or prepared according to conventional methods in the art.

In the present application, copper may be added to the electrolyte in the form of copper sulfate pentahydrate (CuSO4 · 5H ₂ O) or a copper sulfate solution. Sulfuric acid (H ₂ SO ₄ ) is added as a 50-96% solution. The chloride is added in the form of sodium chloride (NaCl) or a solution of hydrochloric acid (HCl).

As shown in FIG. 1, a plate member with a hole on the surface is immersed in the plating solution as a cathode 1, and an anode 2 (such as a titanium electrode covered with a ruthenium-iridium coating) is immersed in the plating solution to immerse the plate member. The anode-connected current source 3 is electroplated after being energized. The electroplating solution enters the copper-dissolving tank 6 with copper particles 5 through the pump 4 to fully react with the copper particles 5. The solution from the copper-dissolving tank 6 will mostly contain vanadium in the form of trivalent vanadium ions, and almost all of the iron will It exists in the form of valent iron ions. After the solution flows back to the electrolytic cell, the trivalent vanadium will quickly react with the trivalent iron in the solution, thereby controlling the concentration of the trivalent iron in the electrolytic cell and ensuring that the vanadium in the electrolytic cell mainly exists in the tetravalent form. Iron exists predominantly in a divalent form.

Example 1 plated through hole

The plating solution of this embodiment includes the following components in terms of mass-volume concentration:

A plate-shaped member with a through hole on the surface is immersed in the plating solution, and the plate-shaped member is used as a cathode to conduct electroplating. The aspect ratio (AR) of the through-hole is 5 and the forward current density is 9A / dm ² , forward current pulse time is 15ms, reverse current density is 27A / dm ² , reverse current pulse time is 1.5ms, plating time is 3h, the difference in TP value can be seen more intuitively through long-term plating .

Comparative Example 1

The plating solution of this comparative example, in terms of mass-volume concentration, contains the following components:

The plating process of this comparative example is the same as in Example 1. After electroplating, the plating effects of the two through holes in this example and this comparative example are shown in Figure 3 (a), Figure 3 (b), and Table 1, respectively.

General hole filling plating solution belongs to high copper and low acid ratio. The mass-volume concentration of copper sulfate is 180g / L ～ 220g / L, and the mass-volume concentration of sulfuric acid is 50-80g / L. In this embodiment, copper sulfate The mass-volume concentration is 140g / L, and the mass-volume concentration of sulfuric acid is 210g / L. It belongs to a low-copper and high-acid plating solution, and is generally not suitable for hole-filling plating solutions. However, from the sectional views of FIGS. 3 (a) and 3 (b), although the plating solution of this embodiment is a low-copper and high-acid plating through-hole plating solution, it has already shown Characteristics, while the comparative example has not added vanadium plating solution to such deep through-holes has been impossible to complete hole filling. The plating effect of through-hole plating is generally measured by measuring the thickness of copper plating at various parts of the through-hole, and then a certain calculation formula (such as formulas 1, 2) is used to obtain a value, and the size of this value reflects the effect of plating. As shown in Figure 2, the areas A1, A2, A3, and A4 are part of the surface of the plate, and B1, B2, B3, and B4 are both ends of the through hole near the opening, and C1 and C2 are through holes. In the middle part, measure the thickness of the electroplated copper layer at the above part.

The two methods for calculating the deep plating ability (TP) of the through-hole plating hole of the plate part by the plating solution can be the method specified by IPC-TM-650 (American Electronics Industry Association Standard) IPC-TP or the method developed by Atotech Calculate the Min-TP value representation, where the calculation formulas of the IPC-TP algorithm and the Min-TP algorithm are shown in formula (1) and formula (2), respectively:

The difference between the two methods is: when the TP value is less than 100%, that is, the inner layer of the hole is thinner than the copper on the surface, the IPC-TM-650 method calculates a larger result; conversely, when the TP value is greater than 100%, that is, the plating layer in the hole When it is thicker than copper, the calculated value of Mini-TP is larger.

Table 1

It can be seen from Table 1 that the deep plating ability of this embodiment 1 is significantly better than that of the control group. For a through hole with an aspect ratio of 5, the hole can be made under the condition of a forward current and reverse current ratio of 1: 3. The middle portions C1 and C2 are preferentially plated. In Comparative Example 1, it is difficult to plate the middle part of the hole with such a high aspect ratio. It can only increase the concentration of copper sulfate and use a smaller positive and negative ratio (such as 1: 4) to achieve it.

Example 2 plated through hole

The plating solution of this embodiment includes the following components in terms of mass-volume concentration:

A plate-shaped member with a through hole on the surface is immersed in the plating solution, wherein the hole diameter of the through-hole is 300 μm and the hole height is 1500 μm, and the plate-shaped member is used as a cathode for electrification, and the forward current density is 10 A / dm ² , the forward current pulse time is 40ms, the reverse current density is 30A / dm ² , the reverse current pulse time is 2ms, and the plating time is 60min.

Comparative Example 2

The plating solution of this comparative example, in terms of mass-volume concentration, contains the following components:

The plating process in this comparative example is the same as in Example 2. After electroplating, the plating effects of the two through-holes in this example 2 and this comparative example 2 are shown in FIG. 4 (a), FIG. 4 (b), and Table 2, respectively.

Table 2

It can be seen from the data in Table 2 that compared to the comparative example 2 without the vanadium system, even if only 1g / L of vanadium is added in this embodiment 2, the effect on the TP value is still obvious. In the process of plating through holes, It can ensure TP> 100%, make the middle part of the hole slightly thicker, and have better deep plating ability.

Example 3 plated through hole

The plating solution of this embodiment includes the following components in terms of mass-volume concentration:

A plate-shaped member with a through hole on the surface is immersed in the plating solution, wherein the hole diameter of the through-hole is 300 μm and the hole height is 1500 μm, and the plate-shaped member is used as a cathode for electrification, and the forward current density is 10 A / dm ² , the forward current pulse time is 40ms, the reverse current density is 30A / dm ² , the reverse current pulse time is 2ms, and the plating time is 30min.

Comparative Example 3

The plating solution of this comparative example, in terms of mass-volume concentration, contains the following components:

The plating process in this comparative example is the same as in Example 3. After plating, the plating effects of the two through-holes in this example 3 and this comparative example 3 are shown in Figs. 5 (a), 5 (b) and Table 3, respectively.

table 3

It can be seen from Table 3 that Example 3 can complete a better plated through-hole effect in 30 minutes. Compared to Comparative Example 3, the Min TP value of the plating solution with the vanadium system added in Example 3 will be larger, indicating that the middle of the hole The parts are plated thicker and have better plating effect.

Example 4 Semi-filled micro-blind hole

The plating solution of this embodiment includes the following components in terms of mass-volume concentration:

A plate member with micro-blind holes (BMV) on the surface is immersed in the plating solution, the hole diameter of the blind hole is 100 μm, and the depth of the hole is 60 μm. The current density is 6A / dm ² , the forward current pulse time is 80ms, the reverse current density is 21A / dm ² , the reverse current pulse time is 4ms, and the plating time is 30min.

The evaluation method of the effect of plating semi-filled micro-blind holes is generally measured by the ratio of the thickness of the thinnest part in the blind hole to the thickness of the surface copper. As shown in FIG. 6, the thicknesses of the plating layers at A and A 'in the figure are measured, and then the thickness of the thinnest one of the three positions marked B in the blind hole is measured. Calculate the TP value of the blind hole according to the following formula (3):

The plating effects of this embodiment are shown in Figure 7 and Table 4, respectively.

Table 4

It can be seen from Table 4 that this embodiment demonstrates a blind hole plating method, which is simple in operation, fast in speed, and good in deep plating ability. The plating can be completed in about 30 minutes, and the thickness of the plated layer is moderate without thinning. It can be seen from FIG. 7 that the thickness distribution of the plating on the board surface is uniform, which improves the production efficiency of the circuit board. DC plated blind holes usually take several hours to reach the same thickness.

Example 5 Semi-filled micro-blind hole

The plating solution of this embodiment includes the following components in terms of mass-volume concentration:

A plate member with micro-blind holes (BMV) on the surface is immersed in the plating solution, the hole diameter of the blind hole is 100 μm, and the depth of the hole is 60 μm. The current density is 9A / dm ² , the forward current pulse time is 40ms, the reverse current density is 27A / dm ² , the reverse current pulse time is 2ms, and the plating time is 30min.

Comparative Example 5

The plating solution of this comparative example, in terms of mass-volume concentration, contains the following components:

A plate member with micro-blind holes (BMV) on the surface is immersed in the plating solution, the hole diameter of the blind hole is 100 μm, and the depth of the hole is 60 μm. The current density is 9A / dm ² , the forward current pulse time is 40ms, the reverse current density is 27A / dm ² , the reverse current pulse time is 2ms, and the plating time is 30min.

The method for evaluating the effect of plated micro-blind holes is the same as the formula (3) of Example 4.

The plating effect of this embodiment and the comparative example are shown in Fig. 8 (a), Fig. 8 (b) and Table 5, respectively.

table 5

Zh

Hole depth (μm)

Aperture (μm)

Coating thickness (μm)

BMV-TP

Zh	Zh	Zh	A	A ’	B	Zh
Example 5	60	100	30.6	30.6	33.5	109%
Comparative Example 5	60	100	31.6	32	27.3	86.8%

From Figure 8 (a), Figure 8 (b) and Table 5, it can be seen that even if the concentration of vanadium and ferric iron is as low as 0.5g / L, electroplating can be completed in about 30 minutes, the plate thickness is moderate, and the TP value Basically meet the requirements.

Example 6 Filling Micro-Blind Holes

The plating solution of this embodiment includes the following components in terms of mass-volume concentration:

A plate-shaped member with a through hole on the surface is immersed in the plating solution, wherein the micro-blind hole has a hole diameter of 100 μm and a hole depth of 60 μm. The plate-shaped member is used as a cathode to perform electroplating. The plating process is as follows: forward current The density is 5A / dm ² , the forward current pulse time is 180ms, the reverse current density is 20A / dm ² , the reverse current pulse time is 20ms, and the plating time is 35min.

The method of evaluating the effect of filling a blind hole is generally measured by the depth from the most concave part of the blind hole to the bottom of the hole to the depth of the copper surface above the bottom of the hole. As shown in Fig. 9, the depths at H1 and H2 in the graph are measured. Calculate the fill rate of blind holes according to the following formula (4):

The plating effects of this embodiment are shown in Figure 10 and Table 6, respectively.

Table 6

It can be seen from FIG. 10 and Table 6 that this embodiment 6 shows a method for filling micro-blind holes. The operation is simple, fast, and the filling rate is high. The plating can be completed in about 35 minutes. Perform thinning. The thickness distribution of the plating on the board surface is uniform, which improves the production efficiency of the circuit board. It is difficult to achieve such a high hole filling rate in DC electroplating blind hole filling, and it usually takes several hours of electroplating to achieve hole filling.

Example 7 Filling Micro-blind Holes

The plating solution of this embodiment includes the following components in terms of mass-volume concentration:

A plate member with micro-blind holes (BMV) on the surface is immersed in the plating solution, the hole diameter of the blind hole is 100 μm, and the depth of the hole is 60 μm. The current density is 6A / dm ² , the forward current pulse time is 100ms, the reverse current density is 20A / dm ² , the reverse current pulse time is 20ms, and the plating time is 30min.

The method of evaluating the effect of the plated micro-blind hole is the same as the formula (4) of Example 6.

The plating effects of this embodiment are shown in Figure 11 and Table 7, respectively.

Table 7

As can be seen from FIG. 11 and Table 7, this embodiment shows a blind hole plating method. The operation is simple and fast, and the deep plating ability meets the requirements of general production lines. The plating can be completed in about 30 minutes, and the thickness of the plated layer is moderate. Perform thinning. The thickness distribution of the plating on the board surface is uniform, which improves the production efficiency of the circuit board.

Example 8 Anode oxygen evolution

The four electrolytes of this embodiment include the following components in terms of mass-volume concentration:

Electrolyte 1:

Electrolyte 2:

Electrolyte 3:

Electrolyte 4:

An electrochemical workstation was used, with a titanium electrode coated with ruthenium and iridium as the working electrode, a saturated calomel electrode (SCE) as the reference electrode, and a platinum electrode as the counter electrode. Three electrodes were immersed in the above electrolyte, and the electrochemical workstation was used. The linear scanning voltammetry (LSV method) measures the polarization curve of titanium-coated electrodes in the above electrolyte. The above four electrolytes are mainly different in the concentration of iron or vanadium ions. Figure 12 shows the LSV curves of the ruthenium-iridium-coated titanium electrodes in these four electrolytes.

It can be seen from FIG. 12 that the LSV curve measured in the electrolyte 1 shows a significant oxygen evolution reaction when the potential is higher than 1.2V. At this time, a large amount of air bubbles are generated on the electrode, and the water is electrolyzed. The LSV curve measured in the electrolyte 2 is due to the addition of ferrous ions and vanadium ions. At the potential of about 0.4V, the electric oxidation current of the ferrous ions appears. During the increase of the potential, it has remained relatively large. The faraday current of the electro-oxidation reaction. If the faraday current of the oxidation reaction fully meets the current strength required for electroplating, the oxygen evolution reaction will not occur on the titanium anode, and the potential continues to increase. When the voltage exceeds 1.2V, the analysis will again occur on the electrode. Oxygen reaction. More vanadium ions were added to electrolyte 3 and electrolyte 4. From the corresponding LSV curve, after the potential exceeded about 1V, the vanadium ions showed a significant electric oxidation current, and the Faraday was oxidized with ferrous ions. The current superposition further reduces the possibility of an oxygen evolution reaction on the titanium anode and improves the reliability of the plating system.

The above embodiments are only used to illustrate the detailed method of the present application, and the present application is not limited to the detailed method, which does not mean that the application must rely on the detailed method to be implemented.

Claims (11)

1. A plating solution comprising the following components in terms of mass concentration:

   
2. The plating solution according to claim 1, wherein a mass-volume concentration of the tetravalent vanadium is 0.5 to 15 g / L.
3. The plating solution according to claim 1 or 2, wherein the mass-volume concentration of the trivalent iron is 0.3 to 2 g / L;

   Optionally, the mass-volume concentration of the trivalent iron is 0.3 to 1.9 g / L.
4. The plating solution according to claim 1, wherein the tetravalent vanadium comprises VOSO ₄ and / or V ₂ O ₄ .
5. The plating solution according to any one of claims 1 to 4, further comprising an additive, the additive including additive A having a mass concentration of 0.2 to 30 ppm and additive B having a mass-to-volume concentration of 0.1 to 3 g / L; Additive A includes sodium polydithiodipropane sulfonate, sodium 3-mercaptopropane sulfonate, sodium N, N-dimethyldithiocarbonylpropane sulfonate, isothiourea propane sulfonate internal salt, and 3- (phenylhydrazone) One or a mixture of at least two of thiazole-2-mercapto) -propane sulfonate;

   The additive B includes a mixture of polyoxypropylene polyoxyethylene ether and polyethylene glycol monomethyl ether.
6. A plating method using the plating solution according to claim 1, wherein a plate member having a hole on the surface is immersed in the plating solution, the plate member is used as a cathode, and electroplating is performed after power is applied.
7. The electroplating method according to claim 6, wherein a forward current density of the current is 1 to 10 A / dm ² , and a reverse current density of the current is 1 to 30 A / dm ² .
8. The electroplating method according to claim 6 or 7, wherein a forward current pulse time of the energization is 20 to 300 ms, and a reverse current pulse time of the energization is 2 to 100 ms.
9. The plating method according to any one of claims 6 to 8, wherein the plating time is 20 to 120 minutes.
10. The electroplating method according to any one of claims 6 to 9, wherein the holes of the plate member are through holes and / or blind holes;

    Optionally, the aspect ratio of the holes is (3-6): 1;

    Optionally, the diameter of the through hole is 200-400 μm;

    Optionally, the diameter of the blind hole is 80-100 μm.
11. The electroplating method according to any one of claims 6 to 10, wherein a plate member having a surface with a through hole and / or a blind hole is immersed in the plating solution, and the aspect ratio of the through hole or the blind hole is (3 ~ 6): 1, the plate-shaped member is used as a cathode, and electroplating is performed after being energized, wherein the forward current density of the energization is 1 to 10A / dm ² , and the reverse current density of the energization is 1 to 30A / dm ² ; The plating time is 20 to 40 min.

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