Copper deposition liquid medicine for printed circuit board and preparation method of copper deposition liquid medicine

Abstract

The invention discloses a copper deposition liquid medicine for a printed circuit board and a preparation method thereof.The copper deposition liquid medicine is formed by mixing a copper deposition liquid medicine A, a copper deposition liquid medicine B and a copper deposition liquid medicine M according to the volume ratio of 1: 1: 1.43, and the copper deposition liquid medicine A comprises 115 g / L of copper sulfate pentahydrate, 225 m l / L of formaldehyde, 20 m l / L of methyl alcohol and 700 g / L of distilled water; the copper deposition stock solution B comprises 70 g / L of sodium potassium tartrate tetrahydrate, 50 g / L of sodium carbonate, 192 g / L of sodium hydroxide, 300 mg / L of potassium ferricyanide and 900 g / L of distilled water; the copper deposition stock solution M comprises 11.16 g / L of sodium hydroxide, 267.84 g / L of sodium potassium tartrate tetrahydrate and 837 g / L of distilled water. According to the method, the problems of thickness uniformity and stability of copper deposition on the surface of the printed circuit board, incapability of copper deposition in micro holes, high cost of copper deposition liquid medicine, short service life of the liquid medicine and the like are solved.

Description

Technical Field

[0001] The invention relates to the technical field of printed circuit board processing, and in particular to a copper plating solution for a printed circuit board and a preparation method thereof. Background Art

[0002] The function of the copper plating solution for circuit boards is to form a uniform copper layer on the substrate of the printed circuit board (PCB) through a chemical reaction. This process mainly relies on the redox reaction in the chemical reaction, which involves the reducing agent reducing the copper ions in the solution into metallic copper and depositing a copper layer on the PCB substrate. The main function of copper plating is to form a conductive copper layer on the PCB substrate for subsequent electroplating and welding processes. This layer of copper not only provides the conductivity of the circuit board, but also ensures that the electronic components on the circuit board can be properly connected and communicated. Copper plating technology can also replace traditional interlayer connection technology to achieve interlayer connection on a single-layer board, reducing the production cost of multi-layer boards. In addition, since copper plating technology can form fine lines and denser wiring, it can improve the integration and performance of PCBs.

[0003] The existing copper plating solution often causes problems such as uneven thickness of the circuit board after copper plating, poor stability, failure to deposit copper in tiny holes, poor conductivity of the circuit board, high cost of the copper plating solution, and short service life of the solution. Although the industry has been committed to research and innovation in this area for many years, including adjusting the solution formula, solution ratio, and the order of preparing the solution, none of them has fundamentally solved the problem. Summary of the invention

[0004] In view of the above-mentioned existing technical defects, the present invention provides a copper plating solution for a printed circuit board and a preparation method thereof, which solves the problems of thickness uniformity and stability of copper plating on the surface of the printed circuit board, failure of copper to be deposited in tiny holes, high cost of the copper plating solution and short service life of the solution.

[0005] In the first aspect, in order to solve the above technical problems, the present invention provides a copper plating solution for a printed circuit board, which is mixed by copper plating solution A, copper plating solution B and copper plating solution M in a volume ratio of 1:1:1.43, wherein the copper plating solution A includes 115 g / L copper sulfate pentahydrate, 225 ml / L formaldehyde, 20 ml / L methanol and 700 g / L distilled water; the copper plating stock solution B includes 70 g / L potassium sodium tartrate, 50 g / L sodium carbonate, 192 g / L sodium hydroxide, 300 mg / L potassium ferrocyanide and 900 g / L distilled water; the copper plating stock solution M includes 11.16 g / L sodium hydroxide, 267.84 g / L potassium sodium tartrate and 837 g / L distilled water.

[0006] In a second aspect, the present invention further provides a method for preparing a copper plating solution for a printed circuit board, comprising the following steps:

[0007] S1. Mix 115 g of copper sulfate pentahydrate with 700 g of distilled water and stir until completely dissolved, then add 225 ml of formaldehyde and then add 20 ml of methanol and stir to mix, filter and obtain 1 L of copper precipitation solution A;

[0008] S2, 70g of potassium sodium tartrate was mixed with 900g of distilled water and stirred until completely dissolved, and then 50g of sodium carbonate was added and stirred, and finally 192g of sodium hydroxide and 300mg of potassium ferrocyanide were added in sequence and stirred and mixed, and 1L of copper precipitation solution B was obtained after filtering;

[0009] S3, 11.16g of sodium hydroxide and 267.84g of potassium sodium tartrate were mixed with 837g of distilled water and stirred until completely dissolved, and 1L of copper precipitation solution M was obtained after filtering;

[0010] S4. Copper precipitation solution A, copper precipitation solution B and copper precipitation solution M are mixed in a volume ratio of 1:1:1.43 to prepare a copper precipitation solution.

[0011] Furthermore, in steps S1-S3, filtering is performed using filter cloth.

[0012] Furthermore, in steps S1-S4, a reaction kettle is used as a reaction vessel for preparing the drug solution, and the reaction vessel and stirring vessel are made of pure steel or plastic.

[0013] Furthermore, in step S1, 20 ml of methanol contains 72 mg of bipyridine.

[0014] Furthermore, in step S2, after adding sodium carbonate, stirring is required for at least 10 minutes before adding sodium hydroxide.

[0015] Furthermore, in step S2, the sodium hydroxide is divided into multiple portions and then added in batches.

[0016] Furthermore, in step S2, the sodium hydroxide is divided into at least three portions and then added in batches.

[0017] Furthermore, in step S4, copper precipitation solution A and copper precipitation solution B are first mixed in proportion, and then copper precipitation solution M is added and stirred for mixing.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. After copper deposition, the copper thickness of the circuit board is uniform, stable and conductive;

[0020] 2. Good effect of micro-hole copper deposition;

[0021] 3. The copper precipitation solution has a long life span and is relatively stable;

[0022] 4. There is less copper on the wall of the copper plating solution, and the utilization rate of copper ions in the solution is high;

[0023] 5. The copper plating solution itself has good stability, which can effectively avoid problems such as solution failure;

[0024] 6. The preparation cost of copper plating solution is low.

[0025] The invention solves the problems of thickness uniformity and stability of copper deposition on the surface of a printed circuit board, failure of copper deposition in tiny holes, high cost of copper deposition solution, and short service life of the solution by adjusting the solution ratio, configuration method, and solution adding sequence. Secondly, the reaction tool and stirring tool used in the solution configuration are made of pure steel or plastic to avoid the reaction of the reaction tool and stirring tool with copper sulfate pentahydrate, potassium sodium tartrate, sodium hydroxide, etc., which may cause impurities in the solution.

[0026] Additional aspects and advantages of the present invention will be given in part in the following description, which will become obvious from the following description, or may be learned through practice of the present invention. DETAILED DESCRIPTION

[0027] In order to more fully understand the technical content of the present invention, the present invention will be further introduced and illustrated in conjunction with specific embodiments below; it should be noted that descriptions such as "first" and "second" in the text are used to distinguish different components, etc., and do not represent the order of precedence, nor do they limit the "first" and "second" to different types.

[0028] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments; based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present invention.

[0029] Example 1

[0030] The copper plating solution for a printed circuit board shown in this embodiment is prepared by mixing copper plating solution A, copper plating solution B and copper plating solution M in a volume ratio of 1:1:1.43.

[0031] Among them, copper precipitation solution A includes 115g / L copper sulfate pentahydrate, 225ml / L formaldehyde, 20ml / L methanol and 700g / L distilled water, that is, each liter of copper precipitation solution A includes 115g copper sulfate pentahydrate, 225ml formaldehyde, 20ml methanol and 700g distilled water.

[0032] The copper precipitation solution B includes 70g / L potassium sodium tartrate, 50g / L sodium carbonate, 192g / L sodium hydroxide, 300mg / L potassium ferrocyanide and 900g / L distilled water, that is, each liter of copper precipitation solution B includes 70g potassium sodium tartrate, 50g sodium carbonate, 192g sodium hydroxide, 300mg potassium ferrocyanide and 900g distilled water.

[0033] The copper precipitation solution M includes 11.16 g / L of sodium hydroxide, 267.84 g / L of potassium sodium tartrate and 837 g / L of distilled water, that is, each liter of copper precipitation solution M includes 11.16 g of sodium hydroxide, 267.84 g of potassium sodium tartrate and 837 g of distilled water.

[0034] The method for preparing the copper plating solution for printed circuit boards comprises the following steps:

[0035] a. Preparation of copper precipitation solution A: 115g of copper sulfate pentahydrate and 700g of distilled water are added to a reactor in sequence, mixed and stirred until completely dissolved, and then 225ml or 190g of formaldehyde and 20ml of methanol are added to the reactor in sequence and stirred and mixed, and 1L of copper precipitation solution A is obtained after filtering, and canned for use;

[0036] b. Preparation of copper precipitation solution B: 70g of potassium sodium tartrate and 900g of distilled water are added to a reactor in sequence, mixed and stirred until completely dissolved, and then 50g of sodium carbonate is added to the reactor, and 192g of sodium hydroxide is added after stirring for at least 10 minutes, and finally 300mg of potassium ferrocyanide is added and stirred to mix, and 1L of copper precipitation solution B is obtained after filtering, and canned for use;

[0037] c. Preparation of copper precipitation solution M: 11.16 g of sodium hydroxide, 267.84 g of potassium sodium tartrate and 837 g of distilled water were added to a reactor in sequence, mixed and stirred until completely dissolved, filtered to obtain 1 L of copper precipitation solution M, and canned for use;

[0038] d. Copper deposition solution A, copper deposition solution B and copper deposition solution M were mixed in a volume ratio of 1:1:1.43 to obtain a copper deposition solution for a printed circuit board.

[0039] In the above, the concentration of formaldehyde: increasing the formaldehyde concentration will speed up the copper deposition, but too much will easily cause the copper deposition layer to be rough. The formaldehyde range should be controlled at 2.8-4.2g / L, and the optimal concentration is 3.5g / L. On the first day of a new tank, the formaldehyde content needs to be increased to 4.0g / L, because the activity of a new tank is low, so the concentration of the liquid needs to be increased.

[0040] Preferably, in steps ac, filter cloth is used to filter the liquid medicine to filter out impurities, so as to avoid the impurities from having adverse effects on the copper deposition of the circuit board.

[0041] Preferably, in steps ad, the reaction kettle used for reaction and the stirring apparatus used for stirring are made of pure steel or plastic, and iron or aluminum products cannot be used, so as to avoid the reaction of the reaction apparatus and the stirring apparatus with copper sulfate pentahydrate, potassium sodium tartrate, sodium hydroxide, etc., which may cause impurities in the drug solution.

[0042] Preferably, 72 mg of bipyridine is contained in 20 ml of methanol.

[0043] In one embodiment, in step b, since the process of adding sodium hydroxide is an exothermic reaction, adding a large amount of sodium hydroxide at the same time will cause severe heat release, it is best to divide the sodium hydroxide into multiple portions and then add them to the reactor in batches.

[0044] Preferably, in step b, the sodium hydroxide is divided into at least three portions and then added to the reactor in batches for reaction.

[0045] In one embodiment, in step d, copper precipitation solution A and copper precipitation solution B are first mixed in proportion, and then copper precipitation solution M is added and stirred to mix.

[0046] In another embodiment, when the copper plating solution is used to perform copper plating treatment on a printed circuit board, according to the size of the copper plating tank and the required amount of copper plating solution, the copper plating solution A, the copper plating solution B and the copper plating solution M are enlarged in a volume ratio of 1:1:1.43 and then added to the copper plating tank for mixing. For example, 100L of copper plating solution A, 100L of copper plating solution B and 143L of copper plating solution M can be added to the copper plating tank, and each liter of copper plating solution A includes 115g of copper sulfate pentahydrate, 225ml of formaldehyde, 20ml of methanol and 700g of distilled water, each liter of copper plating solution B includes 70g of potassium sodium tartrate, 50g of sodium carbonate, 192g of sodium hydroxide, 300mg of potassium ferrocyanide and 900g of distilled water, and each liter of copper plating solution M includes 11.16g of sodium hydroxide, 267.84g of potassium sodium tartrate and 837g of distilled water.

[0047] Comparative Example 1

[0048] The reaction apparatus and / or stirring apparatus in Example 1 is replaced with iron products, and iron ions are introduced into the solution. During the trial production of the copper deposition solution, the solution decomposes over time, thereby affecting the copper deposition effect.

[0049] The technical solutions provided by the embodiments of the present invention are introduced in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the embodiments of the present invention. The description of the above embodiments is only applicable to help understand the principles of the embodiments of the present invention. At the same time, for those skilled in the art, according to the embodiments of the present invention, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A copper plating solution for a printed circuit board, characterized in that: The copper precipitation solution A, copper precipitation solution B and copper precipitation solution M are mixed in a volume ratio of 1:1:1.43, wherein the copper precipitation solution A includes 115g / L copper sulfate pentahydrate, 225ml / L formaldehyde, 20ml / L methanol and 700g / L distilled water; the copper precipitation stock solution B includes 70g / L potassium sodium tartrate, 50g / L sodium carbonate, 192g / L sodium hydroxide, 300mg / L potassium ferrocyanide and 900g / L distilled water; the copper precipitation stock solution M includes 11.16g / L sodium hydroxide, 267.84g / L potassium sodium tartrate and 837g / L distilled water.

2. A method for preparing a copper plating solution for a printed circuit board, characterized in that: The following steps are involved: S1. Mix 115 g of copper sulfate pentahydrate with 700 g of distilled water and stir until completely dissolved, then add 225 ml of formaldehyde and then add 20 ml of methanol and stir to mix, filter and obtain 1 L of copper precipitation solution A; S2, 70g of potassium sodium tartrate was mixed with 900g of distilled water and stirred until completely dissolved, and then 50g of sodium carbonate was added and stirred, and finally 192g of sodium hydroxide and 300mg of potassium ferrocyanide were added in sequence and stirred and mixed, and 1L of copper precipitation solution B was obtained after filtering; S3, 11.16g of sodium hydroxide and 267.84g of potassium sodium tartrate were mixed with 837g of distilled water and stirred until completely dissolved, and 1L of copper precipitation solution M was obtained after filtering; S4. Copper precipitation solution A, copper precipitation solution B and copper precipitation solution M are mixed in a volume ratio of 1:1:1.43 to prepare a copper precipitation solution.

3. The method for preparing the copper plating solution for printed circuit boards according to claim 2, characterized in that: In steps S1-S3, filtering is performed using filter cloth.

4. The method for preparing the copper plating solution for printed circuit boards according to claim 2, characterized in that: In steps S1-S4, a reaction kettle is used as a reaction vessel for preparing the drug solution, and the reaction vessel and the stirring vessel are made of pure steel or plastic.

5. The method for preparing the copper plating solution for printed circuit boards according to claim 2, characterized in that: In step S1, 72 mg of bipyridine is contained in 20 ml of methanol.

6. The method for preparing the copper plating solution for printed circuit boards according to claim 2, characterized in that: In step S2, after adding sodium carbonate, the mixture needs to be stirred for at least 10 minutes before adding sodium hydroxide.

7. The method for preparing the copper plating solution for printed circuit boards according to claim 2, characterized in that: In step S2, the sodium hydroxide is divided into multiple portions and then added in batches.

8. The method for preparing the copper plating solution for printed circuit boards according to claim 7, characterized in that: In step S2, the sodium hydroxide is divided into at least three portions and then added in batches.

9. The method for preparing the copper plating solution for printed circuit boards according to claim 1, characterized in that: In step S4, copper precipitation solution A and copper precipitation solution B are first mixed according to a certain proportion, and then copper precipitation solution M is added and stirred for mixing.