PCB electro-coppering additive, preparation method and application thereof

Abstract

The invention relates to the technical field of electro-coppering additives, and particularly discloses a PCB electro-coppering additive and a preparation method and application thereof.The PCB electro-coppering additive comprises an accelerator, an inhibitor and a leveling agent, the accelerator is sodium 3, 3 '-dithiodipropane sulfonate, the inhibitor is polyethylene glycol-6000, and the leveling agent is sodium dodecyl benzene sulfonate. The leveling agent is at least one organic matter with a chemical formula containing a pyridinium salt structure, the proportion of the accelerator is 1-10 ppm, the proportion of the inhibitor is 150-300 ppm, and the proportion of the leveling agent is 1-10 ppm; according to the method, the activation energy of electroplating reaction can be remarkably reduced and the reduction deposition of copper ions can be promoted by adding the accelerator (sodium polydithiodipropane sulfonate), so that the electroplating speed is increased, the electroplating period is shortened, the production efficiency is improved, the inhibitor (polyethylene glycol-6000) is adsorbed on the surface of the electrode to inhibit excessive deposition of copper in a specific area, and the production efficiency is improved. And a leveling agent (an organic matter containing a pyridinium salt structure) can further level the surface of the plating layer, so that the plating layer is smoother and finer, and the appearance quality and the mechanical property of the plating layer are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of electroplating copper additives, and in particular relates to a PCB electroplating copper additive, a preparation method and application thereof. Background Art

[0002] PCB, or printed circuit board, is one of the important components of the electronics industry. Almost every electronic device, from electronic watches and calculators to computers, communication electronic equipment, and military weapon systems, as long as there are electronic components such as integrated circuits, must use printed circuit boards to make electrical interconnections between the various components. Since the emergence of semiconductor transistors in the 1950s, the demand for printed circuit boards has risen sharply. In particular, the rapid development and widespread application of integrated circuits have made the size of electronic devices smaller and smaller, and the density and difficulty of circuit wiring have become increasingly greater, which requires the continuous updating of printed circuit boards, and high-density interconnection (HDI) technology has emerged. HDI technology is a printed circuit board manufacturing technology that improves wiring density through through holes, blind holes, and buried holes. With the increase in the number of HDI board layers, the thickness-to-diameter ratio of through holes and blind holes is getting larger (≥10), and it is becoming increasingly difficult to achieve conformal plating of through holes and complete filling of blind holes. Relying solely on the existing copper plating technology is far from meeting the high reliability requirements of electronic products.

[0003] Electroplating copper is a common technology in the manufacture of printed circuit boards and IC substrates. It can achieve electrical connection functions such as conduction, interlayer interconnection or shielding layer formation. Electroplating copper is an important intermediate link in the PCB production process, playing an important role in connecting the upper and lower parts. In order to make the physical and chemical properties of the copper plating layer such as thickness, thermal stress, ductility, conductivity, crystallinity, etc. meet the use requirements of PCB, some organic additives need to be added to the electroplating copper plating solution, and the selection and control of these additives are also a major problem. The most commonly used electroplating copper process is the acid copper sulfate electroplating process. Usually, there are three types of acid electroplating copper organic additives: refiner, carrier inhibitor, and leveling agent. For the electroplating of high aspect ratio through holes and blind hole filling, due to the uneven current density distribution at the hole center and hole mouth, the thickness of the hole and surface copper is uneven, and it is difficult to make fine lines with too thick surface copper. Currently available electroplating additives cannot solve this problem. Therefore, how to effectively reduce the thickness of surface copper during electroplating and blind hole filling of high aspect ratio through holes, thereby improving the circuit fineness of today's printed circuit boards, has become a technical problem that needs to be solved urgently in this field. Summary of the invention

[0004] The object of the present invention is to provide a PCB electroplating copper additive, a preparation method and application thereof, so as to solve the problems raised in the above background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A PCB copper electroplating additive comprises: an accelerator, an inhibitor and a leveler, wherein the accelerator is sodium polydisulfide dipropane sulfonate, the inhibitor is polyethylene glycol-6000, and the leveler is an organic substance containing a pyridinium salt structure in at least one chemical formula, the accelerator accounts for 1-10 ppm, the inhibitor accounts for 150-300 ppm, and the leveler accounts for 1-10 ppm.

[0007] Preferably, the chemical formula of the leveling agent is as follows:

[0008]

[0009] Wherein, R1, R2, R3, R4, R5, and R6 are independent of each other or form arbitrary bonds; X - It is an anion.

[0010] A method for preparing a PCB electroplating copper additive comprises the following steps:

[0011] S1. Dissolve the weighed sodium polydisulfide dipropane sulfonate in an appropriate amount of deionized water and stir thoroughly until completely dissolved. Dissolve polyethylene glycol-6000 in an appropriate amount of deionized water, heat and stir to promote dissolution until a clear solution is formed. Dissolve the organic matter containing the pyridinium salt structure in a small amount of deionized water to ensure complete dissolution without precipitation.

[0012] S2. Slowly mix the three solutions in S1 into a clean container, stirring while adding to ensure that the components are evenly distributed to avoid excessive local concentration;

[0013] S3. Detect the pH value of the mixed solution and adjust it to the range required by the electroplating process as needed, confirm whether the final concentration of each component in the mixed solution meets the preset ppm value, and make fine adjustments if necessary;

[0014] S4. Filter the mixed solution through a fine-pore filter to remove impurity particles and obtain a PCB electroplating copper additive.

[0015] Application of a PCB electroplating copper additive, wherein the electroplating temperature is 25-35°C, the electroplating time is 30-60 minutes, and the current density is 2-4A / dm 2 .

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] (1) By adding an accelerator (sodium polydisulfide propane sulfonate), the activation energy of the electroplating reaction can be significantly reduced, and the reduction deposition of copper ions can be promoted, thereby accelerating the electroplating speed, shortening the electroplating cycle, and improving production efficiency. The inhibitor (polyethylene glycol-6000) is adsorbed on the electrode surface to inhibit the excessive deposition of copper in specific areas, which helps to obtain a more uniform and dense coating, reduce surface roughness and defects such as pinholes, and the leveling agent (organic matter containing pyridinium salt structure) can further level the surface of the coating, making the coating smoother and more delicate, and improving the appearance quality and mechanical properties of the coating.

[0018] (2) The use of accelerators can reduce the time and energy consumption required for electroplating. At the same time, inhibitors and levelers help reduce the unevenness of the coating thickness and avoid material waste caused by local excessive thickness or thinness, thereby reducing the cost of electroplating. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a process flow chart of the present invention;

[0020] Figure 2 Levelers at different concentrations have different inhibitory abilities on copper deposition.

[0021] Figure 3 The inhibitory effect of the leveling agent is different under different mass transfer conditions.

[0022] Figure 4 The impedance of the leveling agent adsorbed on the copper surface is different under different mass transfer conditions; DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] Embodiment 1:

[0025] See also Figure 1-4 As shown, a PCB electroplating copper additive comprises:

[0026] Accelerator, inhibitor and leveler, the accelerator is sodium polydisulfide dipropane sulfonate, the inhibitor is polyethylene glycol-6000, and the leveler is an organic substance containing a pyridinium salt structure in at least one chemical formula, the proportion of the accelerator is 1-10ppm, the proportion of the inhibitor is 150-300ppm, and the proportion of the leveler is 1-10ppm.

[0027] In one embodiment of the present invention, the leveler is an ionic compound composed of an organic cation and an anion, the positive charge of the organic cation is mainly concentrated on the quaternary ammonium group of the pyridine ring, and the chemical formula of the leveler is as follows:

[0028]

[0029] Wherein, R1, R2, R3, R4, R5, and R6 are independent of each other or form arbitrary bonds; X - It is an anion.

[0030] A method for preparing a PCB electroplating copper additive comprises the following steps:

[0031] S1. Dissolve the weighed sodium polydisulfide dipropane sulfonate in an appropriate amount of deionized water and stir thoroughly until completely dissolved. Dissolve polyethylene glycol-6000 in an appropriate amount of deionized water, heat and stir to promote dissolution until a clear solution is formed. Dissolve the organic matter containing the pyridinium salt structure in a small amount of deionized water to ensure complete dissolution without precipitation.

[0032] S2. Slowly mix the three solutions in S1 into a clean container, stirring while adding to ensure that the components are evenly distributed to avoid excessive local concentration;

[0033] S3. Detect the pH value of the mixed solution and adjust it to the range required by the electroplating process as needed, confirm whether the final concentration of each component in the mixed solution meets the preset ppm value, and make fine adjustments if necessary;

[0034] S4. Filter the mixed solution through a fine-pore filter to remove impurity particles and obtain a PCB electroplating copper additive.

[0035] Application of a PCB electroplating copper additive, the electroplating temperature is 25-35°C, the electroplating time is 30-60 minutes, and the current density is 2-4A / dm 2 .

[0036] From the above, we can see that during use:

[0037] ① Accurately weigh and mix the following components to prepare an additive concentrate: 0.001-0.01g of sodium polydisulfide dipropane sulfonate as an accelerator, 1.5-3g of polyethylene glycol-6000 as an inhibitor, and 0.001-0.01g of an organic substance containing a pyridinium salt structure as a leveler (all amounts are in ppm, based on the final volume of 1L of solution). Use water as a solvent and adjust the total volume to 1L to obtain an additive concentrate. According to the proportion requirements of different additives, it can be flexibly configured into a variety of additive combinations with specific proportions.

[0038] ② During the electroplating process, the above concentrate is added to the basic electroplating copper solution at a ratio of 1 mL / L. The basic solution is an acid sulfate electroplating copper solution, which is composed of the following components: 60-240 g / L of copper sulfate pentahydrate, 50-250 g / L of concentrated sulfuric acid, and 0.04-0.12 g / L of chloride ions, all with water as the solvent.

[0039] ③Before electroplating, the PCB board must be pretreated as necessary. First, use a degreasing solution composed of 40g / L 85% phosphoric acid, 40g / L ethylene glycol and 1g / L OP-10, and treat it in a constant temperature water bath at 50°C for 15 minutes. Stirring during this period can improve the degreasing efficiency. Subsequently, pickling is performed with 10% sulfuric acid for 1 minute. If flash plating is required, micro-etching is also required. The micro-etching solution consists of 4% sulfuric acid and 90g / L sodium persulfate, and the treatment time is 1 minute.

[0040] ④ The copper electroplating process uses constant current double anode electroplating technology. The anode material is selected according to the electroplating type. Phosphor copper is used as the anode for through-hole conformal electroplating, while iridium tantalum titanium mesh is used for blind hole filling. The cathode is the PCB board to be electroplated, and the plating solution is mechanically stirred by introducing air to ensure that the plating solution components are evenly distributed.

[0041] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A PCB electroplating copper additive, characterized in that: include: An accelerator, an inhibitor and a leveler, wherein the accelerator is sodium polydisulfide dipropane sulfonate, the inhibitor is polyethylene glycol-6000, and the leveler is an organic substance having a pyridinium salt structure in at least one chemical formula. The proportion of the accelerator is 1-10 ppm, the proportion of the inhibitor is 150-300 ppm, and the proportion of the leveler is 1-10 ppm.

2. According to the PCB electroplating copper additive of claim 1, the chemical formula of the leveling agent is as follows: in, R1, R2, R3, R4, R5, and R6 are independent of each other or can form any bond; X - It is an anion.

3. A method for preparing a PCB electroplating copper additive, characterized in that: The following steps are involved: S1. Dissolve the weighed sodium polydisulfide dipropane sulfonate in an appropriate amount of deionized water and stir thoroughly until completely dissolved. Dissolve polyethylene glycol-6000 in an appropriate amount of deionized water, heat and stir to promote dissolution until a clear solution is formed. Dissolve the organic matter containing the pyridinium salt structure in a small amount of deionized water to ensure complete dissolution without precipitation. S2. Slowly mix the three solutions in S1 into a clean container, stirring while adding to ensure that the components are evenly distributed to avoid excessive local concentration; S3. Detect the pH value of the mixed solution and adjust it to the range required by the electroplating process as needed, confirm whether the final concentration of each component in the mixed solution meets the preset ppm value, and make fine adjustments if necessary; S4. Filter the mixed solution through a fine-pore filter to remove impurity particles and obtain a PCB electroplating copper additive.

4. An application of a PCB electroplating copper additive, characterized in that: The electroplating temperature is 25-35°C, the electroplating time is 30-60 minutes, and the current density is 2-4 dm / dm 2 .

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