Additive for neutral electrotinning and preparation method thereof

Abstract

The invention discloses an additive for neutral electrotinning and a preparation method of the additive. The additive comprises the following components: a grain refiner, 10-70 g / L of a surfactant, 0.5-10 g / L of a brightener, 0.5-5 g / L of a defoaming agent and the balance of water. According to the additive for neutral electrotinning, the grain size of a tin layer can be effectively refined, the current density range of a bright plating layer is expanded, and the effect is excellent.

Description

Technical Field

[0001] This invention relates to the field of electroplating, and more specifically to a neutral tin plating additive and its preparation method. Background Technology

[0002] As electronic products continue to evolve towards higher density and miniaturization, microelectronic components such as chip resistors, chip capacitors, and surface-mount inductors are widely used. These devices typically require electrochemical plating of a tin layer during manufacturing to improve their solderability and ensure reliable subsequent soldering onto circuit boards. Compared to traditional acidic or alkaline tin plating systems, neutral tin plating processes are the preferred choice for micro-component electroplating because they are non-corrosive to the device structure and effectively prevent damage or malfunction caused by acidic or alkaline environments. Furthermore, neutral systems help reduce component adhesion during electroplating, improving yield.

[0003] Existing neutral tin plating additives are few and have problems such as coarse tin layer grains and narrow current density adaptability. Developing an additive that can significantly refine tin plating grains, improve plating density, and avoid scorching in high current density areas is an urgent technical problem to be solved. Summary of the Invention

[0004] To address the problems in existing technologies, this invention provides a neutral tin plating additive and its preparation method. This neutral tin plating additive can effectively refine the grain size of the surface tin plating layer.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] This invention provides a neutral tin plating additive, which uses deionized water as a solvent and contains at least the following components: grain refiner, surfactant 10-70 g / L, brightener 0.5-10 g / L, and defoamer 0.5-5 g / L.

[0007] Furthermore, the grain refiner shown comprises the following components: polyether A 10-50 g / L, polyether B 5-30 g / L;

[0008] Polyether A is one of bisphenol A polyoxyethylene ether, bisphenol A polyoxypropylene ether, bisphenol A polyoxyethylene-polyoxypropylene block copolymer ether, dodecyl alcohol polyoxyethylene ether, lauryl alcohol polyoxyethylene ether and cashew phenol polyoxyethylene ether.

[0009] Polyether B is one of sulfonated bisphenol A polyoxyethylene ether, polyethylene oxide polyoxypropylene monobutyl ether, bisphenol A polyoxypropylene ether, bisphenol A polyoxyethylene-polyoxypropylene block copolymer ether, dodecyl alcohol polyoxyethylene ether, lauryl alcohol polyoxyethylene ether and cashew nut phenol polyoxyethylene ether.

[0010] Furthermore, the molecular weight of polyether A is 300-1400, and its addition amount is 10-50 g / L; the molecular weight of polyether B is 2000-4000, and its addition amount is 5-30 g / L.

[0011] Further, the surfactant comprises at least one of the following components: naphthol polyoxyethylene ether BNO12, polyethylene glycol (multiple molecular weights), and propylene glycol polyoxyethylene polyoxypropylene ether. Its addition amount is 10-70 g / L.

[0012] Further, the brightener comprises at least one of the following components: benzyl acetone, sodium saccharin, vanillin, o-vanillin, methyl vanillin, ethyl vanillin, benzaldehyde, cinnamaldehyde, and furfural acetone, with a concentration range of 0.5-10 g / L, more preferably 1-5 g / L.

[0013] Further, the defoamer includes at least one of the following components: polypropylene glycol PPG-400, PPG-600, PPG-800, PPG-1000, PPG-1500, PPG-2000, and PPG-3000, with a concentration range of 0.5-5 g / L.

[0014] The present invention also includes a method for preparing the above-described additive for neutral tin plating, comprising the following components in concentration: water, grain refiner, surfactant, brightener, and defoamer;

[0015] Add a certain amount of water to the container and stir.

[0016] Add the grain refiner to the water being stirred, and stir until a clear solution is formed;

[0017] Next, add the surfactant and brightener, stir for 30 minutes to obtain a mixed solution;

[0018] Add the remaining water and defoamer to the mixed solution and stir for 30 minutes to obtain the additive for neutral tin plating.

[0019] The beneficial results of this invention are as follows:

[0020] (1) This invention provides a neutral tin plating additive that does not contain heavy metals such as fluoroborate, lead, and bismuth. The treatment cost of the plating solution is low and it will not cause pollution to the environment, meeting the requirements of safety and environmental protection.

[0021] (2) The neutral tin plating additive provided by the present invention can effectively improve the cathodic polarization capability of the plating solution and obtain a plating layer with dense crystals, small grains and no voids.

[0022] (3) The neutral tin plating additive provided by the present invention can effectively suppress the burning phenomenon in high current density areas and obtain a dense and uniform plating layer in a wider current density range. Attached Figure Description

[0023] Figure 1 Scanning electron microscope (SEM) image of the Sn coating prepared by adding the neutral tin plating solution of Example 1.

[0024] Figure 2 Scanning electron microscope (SEM) image of the Sn coating prepared by adding the neutral tin plating solution of Example 2.

[0025] Figure 3 The appearance of the Hull cell specimen obtained by electroplating with a 0.5A current for 5 minutes in the neutral tin plating solution of Example 1.

[0026] Figure 4 For comparison, the appearance of the Hull cell specimen obtained by electroplating with a neutral tin plating solution without additives at a current of 0.5A for 5 minutes. Detailed Implementation

[0027] The embodiments of the present invention will be described in further detail below.

[0028] This invention discloses an additive for neutral tin plating solution and its preparation method.

[0029] Neutral tin plating additives consist of the following components: grain refiner, surfactant 10-70 g / L, brightener 0.5-10 g / L, and defoamer 0.5-5 g / L.

[0030] The grain refiner comprises the following components: polyether A 10-50 g / L, polyether B 5-30 g / L; polyether A is one of bisphenol A polyoxyethylene ether, bisphenol A polyoxypropylene ether, bisphenol A polyoxyethylene-polyoxypropylene block copolymer ether, dodecyl alcohol polyoxyethylene ether, lauryl alcohol polyoxyethylene ether, and cashew nut phenol polyoxyethylene ether; the molecular weight of polyether A is 300-1400, and its addition amount is 10-50 g / L.

[0031] Polyether B is one of sulfonated bisphenol A polyoxyethylene ether, polyethylene oxide polyoxypropylene monobutyl ether, bisphenol A polyoxypropylene ether, bisphenol A polyoxyethylene-polyoxypropylene block copolymer ether, dodecyl alcohol polyoxyethylene ether, lauryl alcohol polyoxyethylene ether, and cashew nut phenol polyoxyethylene ether; the molecular weight of polyether B is 2000-4000, and its addition amount is 5-30 g / L.

[0032] The surfactant includes at least one of the following components: naphthol polyoxyethylene ether BNO12, polyethylene glycol (multiple molecular weights), and propylene glycol polyoxyethylene polyoxypropylene ether. The addition amount is 10-70 g / L.

[0033] The brightener includes at least one of the following components: benzyl acetone, sodium saccharin, vanillin, o-vanillin, veratral, ethyl vanillin, benzaldehyde, cinnamaldehyde, and furfural acetone, with a concentration range of 0.5-10 g / L, more preferably 1-5 g / L.

[0034] The defoamer includes at least one of the following components: polypropylene glycol PPG-400, PPG-600, PPG-800, PPG-1000, PPG-1500, PPG-2000, and PPG-3000, with a concentration range of 0.5-5 g / L.

[0035] The present invention also includes a method for preparing the above-described additive for neutral tin plating, comprising the following components in concentration: water, grain refiner, surfactant, brightener, and defoamer;

[0036] Add a certain amount of water to the container and stir.

[0037] Add the grain refiner to the water being stirred, and stir until a uniform and clear solution is formed;

[0038] Next, add the surfactant and brightener, stir for 30 minutes to obtain a mixed solution;

[0039] Add the remaining water and defoamer to the mixed solution and stir evenly to obtain the additive for neutral tin plating.

[0040] Example 1

[0041] (1) Add 50% by mass of deionized water to the mixing tank and start stirring;

[0042] (2) Add 25 g / L bisphenol A polyoxyethylene ether and 25 g / L polyethylene oxide polyoxypropylene monobutyl ether to deionized water and stir until a uniform and clear solution is formed.

[0043] (3) Next, add 50 g / L naphthol polyoxyethylene ether BNO12 and 1 g / L o-vanillin, stir for 30 min, and obtain a mixed solution.

[0044] (4) Add 1 g / L PPG-600 and the remaining water, and stir evenly to obtain an additive for neutral tin plating.

[0045] Example 2

[0046] (1) Add 50% by mass of deionized water to the mixing tank and start stirring;

[0047] (2) Add 36 g / L bisphenol A polyoxyethylene-polyoxypropylene block copolymer ether and 10 g / L polyethylene oxide-polyoxypropylene monobutyl ether to deionized water and stir until a uniform and clear solution is formed.

[0048] (3) Next, add 18 g / L polyethylene glycol PEG6000 and 3.5 g / L veratral, stir for 30 min, and obtain a mixed solution.

[0049] (4) Add 1 g / L PPG-400 and the remaining water, and stir evenly to obtain an additive for neutral tin plating.

[0050] Example 3

[0051] (1) Add 50% by mass of deionized water to the mixing tank and start stirring;

[0052] (2) Add 50 g / L lauryl alcohol polyoxyethylene ether and 15 g / L cashew phenol polyoxyethylene ether to deionized water and stir until a uniform and clear solution is formed.

[0053] (3) Next, add 10 g / L propylene glycol polyoxyethylene polyoxypropylene ether (L64) and 2 g / L sodium saccharin, stir for 30 min, and obtain a mixed solution.

[0054] (4) Add 1 g / L PPG-2000 and the remaining water, and stir evenly to obtain an additive for neutral tin plating.

[0055] Test Examples

[0056] The test method of the experimental embodiments of the present invention is as follows:

[0057] Prepare stannous methanesulfonate (Sn) of the same concentration 2+ =20g / L), 36g / L boric acid, 90g / L methanesulfonic acid, 2g / L hydroquinone, 100g / L glucono-delta-lactone, with pH adjusted to 6.5 using ammonia. Boric acid and ammonia act as buffers in the neutral tin plating solution, methanesulfonic acid as a conductive agent, hydroquinone as an antioxidant, and glucono-delta-lactone as a complexing agent. Add 10mL / L of neutral tin plating additive.

[0058] In the above preparation, 10 mL / L neutral tin plating additive refers to 10 mL of the neutral tin plating additive from Example 1, Example 2, or Example 3 in 1 L of mixed solution. Using the same method, plating solutions were prepared as comparative examples. Electroplating was performed in these solutions at 0.2 A / dm² for 5 minutes, and the surface morphology was examined using a scanning electron microscope. Furthermore, Hull cell specimens were electroplated in the prepared solutions at a current of 0.5 A in a 267 mL Hull cell for 5 minutes.

[0059] Figure 1 and Figure 2 The images show scanning electron microscope (SEM) images of the electroplated coatings from Examples 1 and 2. The images show that the Sn coating obtained by adding the neutral tin plating additive to the electroplating solution has fine and uniform grains, dense crystals, no voids or pores on the surface, and good microstructure.

[0060] Figure 3 and Figure 4 The images show the appearance of the Hull cell test pieces for Example 1 and the comparative example electroplating. As can be seen from the figures, after adding the neutral electroplating tin additive, no scorching areas appear in the high current density area, and the overall coating is uniform, allowing for the acquisition of a bright coating over a wide current density range.

Claims

1. An additive for neutral tin plating, characterized in that, The additive uses deionized water as a solvent and includes at least the following components: grain refiner, surfactant 10-70 g / L, brightener 0.5-10 g / L, and defoamer 0.5-5 g / L.

2. The neutral tin plating additive according to claim 1, characterized in that, The grain refiner includes: polyether A, with an addition amount of 10-50 g / L and a molecular weight of 300-1400; and polyether B, with an addition amount of 5-30 g / L and a molecular weight of 2000-4000.

3. The neutral tin plating additive according to claim 2, characterized in that, The polyether A is selected from one of the following: bisphenol A polyoxyethylene ether, bisphenol A polyoxypropylene ether, bisphenol A polyoxyethylene-polyoxypropylene block copolymer ether, dodecyl alcohol polyoxyethylene ether, lauryl alcohol polyoxyethylene ether, and cashew phenol polyoxyethylene ether.

4. The neutral tin plating additive according to claim 2, characterized in that, The polyether B is selected from one of the following: sulfonated bisphenol A polyoxyethylene ether, polyethylene oxide polyoxypropylene monobutyl ether, bisphenol A polyoxypropylene ether, bisphenol A polyoxyethylene-polyoxypropylene block copolymer ether, dodecyl alcohol polyoxyethylene ether, lauryl alcohol polyoxyethylene ether, and cashew nut phenol polyoxyethylene ether.

5. The neutral tin plating additive according to claim 1, characterized in that, The surfactant is selected from one or more of the following: naphthol polyoxyethylene ether BNO12, polyethylene glycol (multiple molecular weights), propylene glycol polyoxyethylene polyoxypropylene ether.

6. The neutral tin plating additive according to claim 1, characterized in that, The brightener is selected from one or more of the following: benzyl acetone, sodium saccharin, vanillin, o-vanillin, methyl vanillin, ethyl vanillin, benzaldehyde, cinnamaldehyde, furfural acetone; the concentration range of the brightener is 0.5-10 g / L, preferably 1-5 g / L.

7. A method for preparing a neutral tin plating additive as described in any one of claims 1-7, characterized in that, Includes the following steps: (1) Add a certain amount of deionized water to the stirring container; (2) Add a grain refiner to the container and stir until a clear solution is formed; (3) Add surfactant and brightener, stir for 30 minutes to form a mixed solution; (4) Add the remaining water and defoamer to the mixed solution and continue stirring for 30 minutes to obtain a neutral tin plating additive.

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