Metal conductive liquid and its application

Abstract

The present invention relates to a metal conductive liquid and its application, wherein the metal conductive liquid comprises an electroplating additive, an auxiliary agent and a solvent as shown in Formula I. The metal conductive liquid of the present invention has good deep plating ability, and the thickness difference between the dense hole area and the large copper surface area of ​​the electroplated layer is small.

Description

Technical Field

[0001] The invention relates to the technical field of metal conductive liquids, and in particular to a metal conductive liquid and applications thereof. Background Art

[0002] With the development of 5G projects, base station construction has continuously promoted the improvement of circuit board manufacturing technology; the requirements for base station boards and high-frequency boards have been continuously improved, the thickness of circuit boards has increased, the aperture of vias has become smaller, and high aspect ratio boards have appeared. This type of circuit board has a large unit area, large board thickness, small aperture, high hole density, small pad diameter, small wiring width, small line spacing, and a large number of layers.

[0003] In the traditional electroplating process, the current distribution in the through-hole area of ​​the circuit board is uneven and the range is large. It cannot ensure that the copper thickness in the hole and on the board surface is uniform after electroplating. The copper thickness in the hole is thick at both ends and thin in the middle. The copper thickness is thin, that is, the TP value is low. The mainstream equipment currently used for full-board electroplating of PCBs is the vertical continuous electroplating equipment (VCP). Compared with the traditional vertical gantry electroplating line, it has the advantages of good plating uniformity and strong through-hole ability. However, when using traditional electroplating reagents, it is still impossible to compensate for the thickening of the local dense hole area on the PCB. At present, the general process is to first VCP full-board electroplating, and then perform local thickening by gantry electroplating, but it increases production costs and reduces production efficiency.

[0004] CN107217282A discloses a high TP value soft board electroplating solution and electroplating method. The high TP value soft board electroplating solution disclosed therein comprises AE components, wherein the A component is anhydrous copper sulfate; the B component is sulfuric acid; the C component is chloride; the D component is selected from one or a mixture of at least two of polydisulfide dipropane sulfonate sodium, 3-mercaptopropane sulfonate sodium, N,N-dimethyldithiocarbonyl propane sulfonate sodium, isothiourea propane sulfonic acid inner salt and 3-(benzothiazole-2-mercapto)-propane sulfonate sodium; the E component is selected from one or a mixture of at least two of polyethylene glycol, polypropylene glycol and fatty amine polyoxyethylene ether. The high TP value soft board electroplating solution disclosed therein has a low total organic carbon content, high ductility and thermal shock reliability of electroplated copper, a high TP value of the through hole of the soft board, and can use a high current density at the same time, and can be widely used for fine through hole copper plating of soft boards.

[0005] CN201924097U discloses an electroplating device, which relates to the field of electroplating technology. It solves the technical problem that the thickness of the coating formed by the existing electroplating method varies greatly in different areas, resulting in a low product yield. The disclosed electroplating device includes: a power supply; a container for storing electroplating liquid; a metal ion source object as an anode immersed in the electroplating liquid; an object to be plated as a cathode immersed in the electroplating liquid; metal ions adhere to the object to be plated and form a coating under the action of the electric line between the metal ion source object and the object to be plated; an electric line adjustment device for adjusting the distribution of the electric line from the metal ion source object to the object to be plated.

[0006] At present, the main method to reduce the thickness difference in the dense hole area is to improve the equipment, but the overall effect is weak, and most of the time it is at the expense of production efficiency in exchange for performance.

[0007] In summary, it is crucial to develop a metal conductive liquid with good deep plating ability and a small difference in the thickness of the electroplating layer between dense holes and large copper surfaces. Summary of the invention

[0008] In view of the deficiencies in the prior art, the object of the present invention is to provide a metal conductive liquid and its application, wherein the metal conductive liquid has good deep plating ability, and the thickness difference of the plated layer after electroplating in the dense hole area and the large copper surface area is small.

[0009] To achieve this object, the present invention adopts the following technical solutions:

[0010] In a first aspect, the present invention provides a metal conductive liquid, the metal conductive liquid comprising an electroplating additive, an auxiliary agent and a solvent as shown in Formula I;

[0011] Z1-R-(CH2) n -R-Z2 Formula Ⅰ;

[0012] Where n is 1 or 2;

[0013] R is selected from S or CH2;

[0014] Z1 and Z2 are each independently selected from -(C2H4Y) a -(C3H6Y) b -A-CH2-M

[0015] Y is selected from O or an amine group;

[0016] A is selected from a single bond, NH or CH2;

[0017] M is selected from -SO3-H or -SO3-Na

[0018] a and b are each independently an integer of 1-10 (eg, 2, 3, 4, 5, 6, 7, 8, 9, etc.).

[0019] In the present invention, the electroplating additive has a polyether-containing structure or a sulfur-containing structure, which can affect the adsorption mode, adsorption site, adsorption amount and response rate to current of the metal conductive liquid on the copper surface, thereby causing acceleration, inhibition, deep plating, dispersion ability and other effects on the electroplating copper process. Specifically, the metal conductive liquid has a significant accelerating electroplating effect in the dense hole area (low current area), increases the metal thickness in the dense hole area, and exhibits good deep plating ability and small thickness difference between the plating layer in the dense hole area and the large copper surface area.

[0020] In the present invention, "-" represents a connection site.

[0021] Preferably, n is selected from methyl or ethyl.

[0022] Preferably, when Y is selected from an amine group, A is a single bond and M is -SO3-Na.

[0023] Preferably, the electroplating additive includes any one or a combination of at least two of Compound 1 to Compound 7;

[0024]

[0025]

[0026] Wherein, a and b are each independently an integer of 1-10, such as 2, 3, 4, 5, 6, 7, 8, 9, etc.

[0027] Preferably, in the electrolyte, the concentration of the electroplating additive is 1-1000 mg / L, for example, 10 mg / L, 50 mg / L, 100 mg / L, 200 mg / L, 300 mg / L, 400 mg / L, 500 mg / L, 600 mg / L, 700 mg / L, 800 mg / L, 900 mg / L, etc.

[0028] Preferably, the auxiliary agent includes any one of a wetting agent, a leveling agent or a brightening agent, or a combination of at least two of them.

[0029] In the present invention, the electroplating additive has a combined effect of a wetting agent and a brightener, and other wetting agents or brighteners can be selected according to needs.

[0030] Illustratively, the wetting agent includes polyethylene glycol and / or polyether.

[0031] Exemplarily, the brightener includes sodium polydipropylene sulfonate.

[0032] Exemplarily, in the present invention, the metal conductive liquid is an acid copper metal conductive liquid, comprising the following components:

[0033] Copper sulfate pentahydrate 60-100g / L, such as 70g / L, 80g / L, 90g / L, etc.;

[0034] Sulfuric acid 200-250g / L, such as 210g / L, 220g / L, 230g / L, 240g / L, etc.;

[0035] Chloride 60-100 mg / L, such as 70 mg / L, 80 mg / L, 90 mg / L, etc.;

[0036] Wetting agent 300-800 mg / L, such as 400 mg / L, 500 mg / L, 600 mg / L, 700 mg / L, etc.;

[0037] Brightener 1-3mg / L, such as 1.5mg / L, 2mg / L, 2.5mg / L, etc.;

[0038] The electroplating additive shown in Formula I is 1-1000 mg / L, for example, 200 mg / L, 300 mg / L, 400 mg / L, 500 mg / L, 600 mg / L, 700 mg / L, 800 mg / L, 900 mg / L, etc.

[0039] In a second aspect, the present invention provides a use of the metal conductive liquid described in the first aspect in through-hole electroplating.

[0040] Exemplarily, the process flow of the metal conductive liquid in through-hole electroplating includes the following steps:

[0041] Degreasing - water washing - micro-etching - water washing - pre-dipping - electroplating - water washing - drying.

[0042] Exemplarily, the current density of the electroplating is 1-3A / dm 2 , for example 1.5A / dm 2 , 2A / dm 2 , 2.5A / dm 2 wait.

[0043] The electroplating method is direct current electroplating or pulse electroplating.

[0044] Exemplarily, the electroplating time is 50-200 min, for example, 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, 90 min, etc.

[0045] Exemplarily, the electroplating temperature is 10-40°C, such as 15°C, 20°C, 25°C, 30°C, 35°C, etc.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] (1) The metal conductive liquid of the present invention has good deep plating ability, and the thickness difference between the dense hole area and the regular area of ​​the plated layer after electroplating is small.

[0048] (2) The deep plating capability of the metal conductive liquid of the present invention is above 91%, and the thickness difference between the dense hole area and the conventional area is within 9 μm. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 This is a picture of a test board with a thickness of 3 mm after the metal conductive liquid described in Example 1 has completed the test;

[0050] Figure 2 This is a picture of a test board with a thickness of 3 mm after the metal conductive liquid described in Example 2 has completed the test;

[0051] Figure 3 This is a picture of a test board with a thickness of 3 mm after the metal conductive liquid described in Example 3 has completed the test;

[0052] Figure 4 This is a picture of a test board with a thickness of 6 mm that was tested using the metal conductive liquid described in Example 1. DETAILED DESCRIPTION

[0053] For the convenience of understanding the present invention, the present invention lists the following embodiments. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0054] Example 1

[0055] This embodiment provides a metal conductive liquid, which is composed of the following components:

[0056]

[0057]

[0058] Example 2

[0059] This embodiment provides a metal conductive liquid, which is composed of the following components:

[0060]

[0061]

[0062]

[0063] Example 3

[0064] This embodiment provides a metal conductive liquid, which is composed of the following components:

[0065]

[0066] The electroplating additive is prepared by the following method, which comprises the following steps:

[0067]

[0068] Example 4

[0069] This embodiment provides a metal conductive liquid, which is composed of the following components:

[0070]

[0071]

[0072]

[0073] Example 5

[0074] This embodiment provides a metal conductive liquid, which is composed of the following components:

[0075]

[0076]

[0077] Example 6

[0078] This embodiment provides a metal conductive liquid, which is composed of the following components:

[0079]

[0080]

[0081]

[0082] Example 7

[0083] This embodiment provides a metal conductive liquid, which is composed of the following components:

[0084]

[0085]

[0086] Performance Testing

[0087] The metal conductive liquids described in Examples 1-7 were tested as follows:

[0088] (1) Throwing ability: The throwing ability is characterized by the TP value, that is, TP = average thickness in the middle of the hole excluding the bottom copper thickness / average plated copper thickness.

[0089] Specifically, the process flow is: degreasing (treatment at 40°C for 5 minutes) - water washing - micro-etching (treatment at 30°C for 1 minute) - water washing - pre-dipping (treatment at 30°C for 0.5 minutes) - electroplating - water washing - drying. The current density of electroplating is 2A / dm 2 , electroplating time 60min, temperature 25℃.

[0090] (2) Thickness difference between dense hole area and large copper surface area: Measure the thickness of the two areas five times at different locations, find the average value, and calculate the difference.

[0091] The test results are summarized in Table 1 and Figure 1-4 middle.

[0092] Table 1

[0093] Throwing capacity (%) Thickness difference / μm Example 1 95 6 Example 2 99 5 Example 3 91 9 Example 4 101 6 Example 5 98 8 Example 6 96 6 Example 7 96 5

[0094] Analysis of the data in Table 1 shows that the deep plating ability of the metal conductive liquid of the present invention is above 91%, and the thickness difference between the dense hole area and the conventional area is within 9 μm; the metal conductive liquid of the present invention has good deep plating ability, and the thickness difference between the dense hole area and the large copper surface area of ​​the plated layer after electroplating is small.

[0095] Figure 1 , Figure 2 and Figure 3 The dimensions in the figure are the aperture dimensions, the thickness of the test board is 3 mm, and the aspect ratio AR is close to 15:1.

[0096] Figure 4 Taking Example 1 as an example, the thickness of the test board is 6 mm, the aspect ratio reaches AR=30:1, and TP>90%.

[0097] The applicant declares that the present invention illustrates the detailed method of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned detailed method, that is, it does not mean that the present invention must rely on the above-mentioned detailed method to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of various raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A metal conductive liquid, characterized in that: The metal conductive liquid comprises an electroplating additive, an auxiliary agent and a solvent as shown in Formula I; Z1-R-(CH2) n -R-Z2 Formula Ⅰ; Where n is 1 or 2; R is selected from S or CH2; Z1 and Z2 are each independently selected from -(C2H4Y) a -(C3H6Y) b -A-CH2-M Y is selected from O or an amine group; A is selected from a single bond, NH or CH2; M is selected from -SO3-H or -SO3-Na a and b are each independently an integer of 1-10.

2. The metal conductive liquid according to claim 1, characterized in that: When Y is selected from an amine group, A is a single bond and M is -SO3-Na.

3. The metal conductive liquid according to claim 1, characterized in that: The electroplating additive includes any one or a combination of at least two of Compound 1 to Compound 7; wherein a and b are each independently an integer of 1-10.

4. The metal conductive liquid according to claim 1, characterized in that: The concentration of the electroplating additive is 1-1000 mg / L.

5. The metal conductive liquid according to claim 1, characterized in that: The auxiliary agent includes any one of a wetting agent, a leveling agent or a brightening agent, or a combination of at least two of them.

6. The metal conductive liquid according to claim 1, characterized in that: The solvent includes any one of water, lower alcohol or lower ketone, or a combination of at least two of them.

7. Use of the metal conductive liquid according to any one of claims 1 to 6 in through-hole electroplating.

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