阅读说明：本技术 一种电路板内层铜箔棕化液 (Browning liquid for inner layer copper foil of circuit board ) 是由 闫肖阳 张玲玲 刘洋 王康 王德娟 靳峥 李秋 于 2020-07-31 设计创作，主要内容包括：本发明公开了一种电路板内层铜箔棕化液,属于电路板技术领域,由以下组分制成：酸的水溶液100-120份、硫酸锌6-10份、双氧水12-16份、2-巯基苯并噻唑14-18份、缓蚀剂7.5-9份、无机盐2.5-4.2份、添加剂6.4-8份、有机溶剂88-95份。本发明的棕化液剥离强度高达0.92 Kg/cm,热性能测试,分别对压合后样品进行6次浸锡、100次冷热冲击循环,观察测试样均无起泡、分层或爆板现象。表明经过本申请棕化处理后的样品对高温热冲击的承受能力强。微蚀深度在1.32-1.34μm之间,微蚀深度均匀。(The invention discloses a browning liquid for an inner layer copper foil of a circuit board, which belongs to the technical field of circuit boards and is prepared from the following components: 100-120 parts of acid aqueous solution, 6-10 parts of zinc sulfate, 12-16 parts of hydrogen peroxide, 14-18 parts of 2-mercaptobenzothiazole, 7.5-9 parts of corrosion inhibitor, 2.5-4.2 parts of inorganic salt, 6.4-8 parts of additive and 88-95 parts of organic solvent. The peeling strength of the browning liquid is up to 0.92 Kg/cm, the thermal performance test is carried out, the pressed sample is respectively subjected to 6 times of tin immersion and 100 times of cold and hot impact cycles, and the test sample is observed to have no foaming, layering or plate explosion phenomenon. The sample subjected to browning treatment has strong bearing capacity on high-temperature thermal shock. The micro-etching depth is 1.32-1.34 μm, and the micro-etching depth is uniform.)

1. A brown oxide solution for inner copper foil of a circuit board is characterized in that: the composition is prepared from the following components: 100-120 parts of acid aqueous solution, 6-10 parts of zinc sulfate, 12-16 parts of hydrogen peroxide, 14-18 parts of 2-mercaptobenzothiazole, 7.5-9 parts of corrosion inhibitor, 2.5-4.2 parts of inorganic salt, 6.4-8 parts of additive and 88-95 parts of organic solvent.

2. The brown oxide solution for the inner layer copper foil of the circuit board as claimed in claim 1, wherein: the composition is prepared from the following components: 109 parts of acid aqueous solution, 7.5 parts of zinc sulfate, 14 parts of hydrogen peroxide, 16.5 parts of 2-mercaptobenzothiazole, 8.3 parts of corrosion inhibitor, 3.7 parts of inorganic salt, 7.6 parts of additive and 90 parts of organic solvent.

3. The brown oxide solution for the inner layer copper foil of the circuit board as claimed in claim 2, wherein: the acid water solution is formed by mixing sulfuric acid, citric acid and water, wherein the ratio of sulfuric acid: citric acid: the weight ratio of water is 1:0.3-0.5: 1-1.2.

4. The brown oxide solution for the inner layer copper foil of the circuit board as claimed in claim 2, wherein: the concentration of the sulfuric acid is 98%.

5. The brown oxide solution for the inner layer copper foil of the circuit board as claimed in claim 2, wherein: the corrosion inhibitor is prepared by mixing 4-carboxyl benzotriazole, urotropine, zinc molybdate, methyl triethoxysilane and polyethylene glycol.

6. The brown oxide solution for the inner layer copper foil of the circuit board as claimed in claim 2, wherein: the inorganic salt is sodium chromate, dipotassium hydrogen phosphate, sodium chromate: the weight ratio of the dipotassium phosphate is 1: 0.6-0.8.

7. The brown oxide solution for the inner layer copper foil of the circuit board as claimed in claim 2, wherein: the additive is dodecyl benzene sulfonic acid, polyacid amide, dodecyl benzene sulfonic acid: the weight ratio of the polyacid amide is 1: 1.2-1.5.

8. The brown oxide solution for the inner layer copper foil of the circuit board as claimed in claim 2, wherein: the organic solvent is polyvinyl alcohol.

Technical Field

The invention relates to the technical field of circuit boards, in particular to a browning liquid for an inner layer copper foil of a circuit board.

Background

The circuit board is one of indispensable electronic component parts in the electronic industry, is a platform for ensuring various electronic elements to realize electrical interconnection, and is applied to almost all electronic equipment, such as calculators, smart phones, notebook computers, aerospace equipment, military weapon systems and the like. The polymer base material used for manufacturing the circuit board is a polymer such as a glass cloth-reinforced epoxy resin, an acrylic resin, polytetrafluoroethylene, polyimide, or the like. A layer of copper foil is covered on one side or two sides of a polymer substrate, then a dry film is covered on the copper surface, and a circuit pattern is formed on the copper surface after processes of exposure, development, etching and the like, and the single-side or double-side printed circuit board is generally manufactured by the method.

With the rapid development of electronic technology, the industry of circuit boards is rapidly increased, the browning technology gradually replaces the blackening technology, is a key technology of a PCB inner layer circuit board pressing procedure, restricts an important procedure of circuit board quality, and leads the output of browning waste liquid to be more and more. In the PCB industry, because the browning treatment process is a chemical copper etching reaction process, the browning treatment has the effect of forming a browning membrane surface layer on a PCB inner layer board to protect a copper base material, the amount of dissolved copper in the browning liquid continuously rises along with the browning process, and when copper ions exceed a certain range, the browning copper surface is influenced, and the quality problems of copper surface whitening, uneven color and the like are caused. Currently, the browning liquid mainly contains high-concentration sulfuric acid, hydrogen peroxide, polyethylene glycol, organic copper microetching agents (such as azole, pyrrole and other compounds) and organic hydrogen peroxide stabilizers (such as EDTA, benzenesulfonic acid and mercaptoacetic acids). The insufficient bonding force between the inner layers of the PCB subjected to the browning treatment by using the browning liquid still causes the phenomena of layering and board explosion between boards in the subsequent processing, so that the development of the browning liquid capable of improving the bonding force between the layers is urgent.

Patent document No. CN104928667B discloses a browning liquid for treating printed circuit boards based on functionalized ionic liquid, which is characterized in that the browning liquid comprises the following raw materials by mass concentration: the concentration of the sulfuric acid is 80-120 g/L; the concentration of hydrogen peroxide is 5-25 g/L; the concentration of the ionic liquid corrosion inhibitor is 5-25 g/L; the concentration of the ionic liquid binding force promoter is 0.5-5.0 g/L; the ionic liquid corrosion agent is an ionic liquid which is formed by taking alkyl substituted or amino substituted benzimidazole as cations and halogen as anions.

Patent document No. CN107365993A discloses a browning liquid and a browning method. The browning liquid comprises a component A-E, wherein the component A is anhydrous zinc sulfate; the component B is sulfuric acid; the component C is chloride; the component D is one or a mixture of at least two of benzotriazole, imidazole and derivatives thereof, and thiazole and derivatives thereof; the component E is nitric acid.

The two browning solutions have poor peel strength resistance, weak bearing capacity of a sample to high-temperature thermal impact, uneven microetching and poor interlayer bonding force.

Disclosure of Invention

In view of the above, the present invention provides a browning liquid for an inner layer copper foil of a circuit board.

In order to solve the technical problems, the technical scheme adopted by the invention is as follows:

a brown oxide solution for an inner layer copper foil of a circuit board is prepared from the following components: 100-120 parts of acid aqueous solution, 6-10 parts of zinc sulfate, 12-16 parts of hydrogen peroxide, 14-18 parts of 2-mercaptobenzothiazole, 7.5-9 parts of corrosion inhibitor, 2.5-4.2 parts of inorganic salt, 6.4-8 parts of additive and 88-95 parts of organic solvent.

Further, the brown oxide solution for the inner layer copper foil of the circuit board is prepared from the following components: 109 parts of acid aqueous solution, 7.5 parts of zinc sulfate, 14 parts of hydrogen peroxide, 16.5 parts of 2-mercaptobenzothiazole, 8.3 parts of corrosion inhibitor, 3.7 parts of inorganic salt, 7.6 parts of additive and 90 parts of organic solvent.

Further, the aqueous solution of the acid is formed by mixing sulfuric acid, citric acid and water, wherein the ratio of sulfuric acid: citric acid: the weight ratio of water is 1:0.3-0.5: 1-1.2.

Further, the concentration of the sulfuric acid is 98%.

Furthermore, the corrosion inhibitor is formed by mixing 4-carboxyl benzotriazole, urotropine, zinc molybdate, methyl triethoxysilane and polyethylene glycol.

Further, the inorganic salt is copper chloride, sodium chromate, dipotassium hydrogen phosphate, copper chloride: sodium chromate: the weight ratio of the dipotassium phosphate to the dipotassium phosphate is 1: 0.6-0.8: 0.2-0.3.

Further, the additive is dodecyl benzene sulfonic acid, polyacid amide, dodecyl benzene sulfonic acid: the weight ratio of the polyacid amide is 1: 1.2-1.5.

Further, the organic solvent is polyvinyl alcohol.

In the manufacturing process of the PCB multilayer board, the delamination between copper and resin is a very representative problem. In order to enhance the bonding force between the inner layers, various researches are conducted by those engaged in the PCB industry, and the black oxidation technology developed in the process becomes the mainstream of the inner layer processing method of the PCB at that time, and is widely applied to the actual production manufacturing process. With the rapid development of the PCB industry and the market demand, PCB enterprises are also striving to improve efficiency, reduce cost, and improve environment while continuing to develop high precision, light weight, and thin type in the manufacturing technology. The traditional blackening process is increasingly difficult to adapt to the requirements of multi-variety and small-batch production, the capability of manufacturing thin plates is poor, the operation flow is long, the environment is poor, the process technology is difficult to control, and the sewage treatment cost is high. The currently replacing mainstream inner layer bonding treatment technology is a browning method. Wherein, the browning liquid mostly adopts an acid system of sulfuric acid and hydrogen peroxide, and then specific organic matters are added. Unevenness is formed on the surface of copper during browning, and the active microscopic roughness increases the contact area with resin during lamination. At present, only a single corrosion inhibitor is usually adopted in the browning liquid, and the performances such as peel strength and the like of the browning liquid need to be improved. For example, difloron, yellow leather, king kejun, high-grade four, king dragon bushy, brown oxidation treatment liquid development of copper foil on the inner layer of a multilayer board [ J ], printed circuit information, 2013, 3:23-26, outlines the brown oxidation process principle applied to the manufacturing process of a PCB multilayer board, discusses a new brown oxidation treatment liquid, and a corrosion inhibitor of the brown oxidation treatment liquid is benzotriazole. Patent document with publication number CN110527996A discloses a browning liquid, a preparation method and applications thereof, including anhydrous copper sulfate, sulfuric acid, chloride, corrosion inhibitor, citric acid and its derivatives, nitric acid and hydrogen peroxide; wherein, in the browning liquid, the mass concentration of the nitric acid is 2-200 g/L. The browning liquid provided by the invention has high copper carrying capacity, less precipitation in the solution, long service life and less pollution; meanwhile, the browning liquid provided by the invention can effectively solve the problems of poor browning of different copper crystals and copper exposure of the wire-repairing alloy through browning. However, the peeling strength of the browning solutions is low, and the comprehensive performance needs to be improved.

The invention has the beneficial effects that:

the invention has the following beneficial effects: the copper foil is browned in the browning liquid, an organic copper film is obtained on the surface, better interface bonding force is provided, higher peeling strength and better heat resistance are achieved, and the thermal shock resistance and the delamination resistance of the laminated board are improved.

The sulfuric acid and the citric acid create an acid environment, and meanwhile, the sulfuric acid and the citric acid cooperate with the oxidant to slightly etch away copper on the surface of the copper foil, so that the bonding force between layers is increased. The hydrogen peroxide slightly etches the surface of the copper foil to form a rough surface. 2-mercaptobenzothiazole, a corrosion inhibitor, sodium chromate and dipotassium hydrogen phosphate act synergistically to form a compact oxide film on the surface of the copper foil, so that the corrosion of the surface of the copper foil is delayed.

The additive polyacid amide can improve the adhesive force of the film, accelerate the formation of the film and improve the thickness of the film. The dodecyl benzene sulfonic acid improves the dispersibility, enhances the compatibility among organic matters and maintains the system balance. The zinc sulfate is cooperated with the corrosion inhibitor to accelerate the film forming speed.

The peeling strength of the browning liquid is up to 0.92 Kg/cm, the thermal performance test is carried out, the pressed sample is respectively subjected to 6 times of tin immersion and 100 times of cold and hot impact cycles, and the test sample is observed to have no foaming, layering or plate explosion phenomenon. The sample subjected to browning treatment has strong bearing capacity on high-temperature thermal shock. The micro-etching depth is 1.32-1.34 μm, and the micro-etching depth is uniform.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention are clearly and completely described below. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the described embodiments of the invention, are within the scope of the invention.

TABLE 1 EXAMPLES 1-6 parts by weight of the components of browning liquid (parts)