阅读说明：本技术 一种用于制备超薄钛箔的化学铣切液及铣切方法 (Chemical milling liquid for preparing ultrathin titanium foil and milling method ) 是由 葛荘 贺贤汉 欧阳鹏 王斌 马敬伟 张恩荣 于 2020-06-03 设计创作，主要内容包括：本发明涉及一种用于制备超薄钛箔的化学铣切液及铣切方法,该铣切液由下述组分组成：体积分数分别为15％～25％的氢氟酸溶液、1％～3％的硝酸溶液、5％～8％的的冰醋酸溶液,浓度为0.1～0.5g/100mL铣切液的缓蚀稳定剂,余量为纯水。铣切方法包括如下工序：1)钛箔表面除油清洗：待处理钛箔依次在丙酮、无水乙醇、纯水中超声浸洗共计5min-10min后烘干取出；2)化学铣切：将经步骤1)处理后的钛箔浸没在所述化学铣切液中1min-4min中进行铣切；3)表面清洗：铣切后的钛箔依次在丙酮、纯水中浸洗共计6min-10min。本发明由于在铣切液中添加使用了缓蚀稳定剂,加入该种稳定剂的化学铣切液铣切均匀、可明显缓解钛箔表面起皱现象、铣切液稳定性高,更适用于加工超薄钛箔焊片。(The invention relates to a chemical milling liquid for preparing an ultrathin titanium foil and a milling method, wherein the milling liquid comprises the following components: 15-25% of hydrofluoric acid solution, 1-3% of nitric acid solution, 5-8% of glacial acetic acid solution, 0.1-0.5 g/100mL of corrosion inhibition stabilizer of milling liquid and the balance of pure water. The milling method comprises the following steps: 1) degreasing and cleaning the surface of the titanium foil: ultrasonically dipping and washing the titanium foil to be treated in acetone, absolute ethyl alcohol and pure water for 5-10 min in sequence, and drying and taking out; 2) chemical milling: immersing the titanium foil treated in the step 1) in the chemical milling liquid for 1-4 min for milling; 3) surface cleaning: and sequentially soaking and washing the milled titanium foil in acetone and pure water for 6-10 min. Because the corrosion inhibition stabilizer is added in the milling liquid, the chemical milling liquid added with the stabilizer is uniform in milling, can obviously relieve the wrinkling phenomenon of the surface of the titanium foil, is high in stability, and is more suitable for processing ultrathin titanium foil soldering lugs.)

1. The chemical milling liquid for preparing the ultrathin titanium foil is characterized by comprising the following components:

15-25% of hydrofluoric acid solution, 1-3% of nitric acid solution, 5-8% of glacial acetic acid solution, 0.1-0.5 g/100mL of corrosion inhibition stabilizer of milling liquid and the balance of pure water.

2. The chemical milling solution for preparing ultra-thin titanium foil as claimed in claim 1, wherein:

wherein the chemical mass fraction of the hydrofluoric acid solution is 3%; the chemical mass fraction of the nitric acid solution is 63%; the chemical mass fraction of the glacial acetic acid solution is 99.5%.

3. The chemical milling solution for preparing ultra-thin titanium foil as claimed in claim 2, wherein:

wherein, the corrosion inhibition stabilizer is one or more of polyacrylamide, polyvinyl alcohol and sodium silicate.

4. The milling method for preparing the ultrathin titanium foil by adopting the chemical milling liquid in the claim 1 is characterized by comprising the following steps:

1) degreasing and cleaning the surface of the titanium foil: ultrasonically dipping and washing the titanium foil to be treated in acetone, absolute ethyl alcohol and pure water for 5-10 min in sequence, and drying and taking out;

2) chemical milling: immersing the titanium foil treated in the step 1) in the chemical milling liquid for 1-4 min for milling;

3) surface cleaning: and sequentially soaking and washing the milled titanium foil in acetone and pure water for 6-10 min.

5. The milling method for preparing the ultrathin titanium foil as recited in claim 1, wherein:

in the step 1), ultrasonically dipping and washing the titanium foil to be treated in an acetone solution for 3-5 min; ultrasonically soaking and washing in absolute ethyl alcohol for 1-3 min; ultrasonically soaking and washing in pure water for 1-3 min,

the drying condition is that the mixture is placed in a drying oven with the temperature of 80-100 ℃ for 10-15 min.

6. The milling method for preparing the ultrathin titanium foil as recited in claim 1, wherein:

wherein, in the step 2), slight ultrasonic vibration is carried out during chemical milling.

7. The chemical milling solution for preparing ultra-thin titanium foil as claimed in claim 1, wherein:

wherein, in the step 3), the titanium foil is soaked and washed in acetone solution for 3min to 5min and in pure water for 3min to 5 min.

Technical Field

The invention belongs to the technical field of semiconductor substrate preparation, relates to a copper-clad ceramic substrate titanium foil soldering lug preparation technology, and particularly relates to chemical milling liquid and a milling method for preparing an ultrathin titanium foil.

Background

The copper-clad ceramic substrate is the most excellent packaging material for a high-voltage high-power module in the field of semiconductors, and has the characteristics of high heat conduction, excellent insulating property, excellent solderability, large current carrying capacity and the like. High temperature direct bonding (DBC, also known as DCB) technology, high temperature active brazing (AMB) technology, electroplating (DPC) technology, and laser activation technology (LAM) are the main technologies for manufacturing copper-clad ceramic substrates at present. The copper-clad ceramic substrate prepared by the AMB technology has the advantages of excellent cold and hot impact resistance, high copper ceramic peeling strength, high cold and hot circulation reliability and the like, and has wide market and application prospects.

Sintering is the most critical part of the AMB technology, and the reduction of the production cost has important significance for industrial mass production on the premise of ensuring the quality. The soldering lug/solder is one of the cores of the AMB sintering technology, meanwhile, due to the AMB process requirement and quality control, an ultrathin titanium foil is required to be used as the soldering lug, the ultrathin titanium foil is mostly applied to the fields of aerospace, loudspeaker sound films and the like, the titanium foil with relatively thick titanium foil (more than or equal to 10 mu m) needs to be rolled for many times, the requirements on equipment and processing technology are strict, the production cost is high, and the problem therewith is the increase of the production cost of the AMB copper-clad plate. Therefore, how to reduce the thickness of the thicker titanium foil by a simple process to be applied to sintering of the AMB copper-clad plate has important significance for reducing cost of the AMB product.

In the field of metal substrate ultra-thinning, chemical milling is an optional mode, and for titanium foil, HF-HNO is mostly adopted₃Chemical milling liquid of the system. HF-HNO₃The milling liquid of the system has the advantage of high speed when the titanium foil is thinned, but has the problems of uneven milling, erosion, excessive wrinkling on the surface of the titanium foil, easy failure of the milling liquid and the like. Thus, conventional HF-HNO is used₃Systematic millingThe cutting liquid is difficult to prepare the ultra-thin titanium foil with excellent quality.

Disclosure of Invention

In order to solve the defects of the prior art, the invention uses a novel corrosion inhibition stabilizer, the chemical milling liquid added with the stabilizer is milled uniformly, can obviously relieve the wrinkling phenomenon of the surface of the titanium foil, has high stability, and is more suitable for processing the ultrathin titanium foil soldering lug.

The key point of the invention for solving the technical problem is to add a novel corrosion inhibition stabilizer, and the principle is that the diffusion rate of ions is reduced by increasing the viscosity of the solution so as to reduce the milling rate, thereby avoiding the over-corrosion of the surface of the titanium foil caused by exponential increase of the later milling rate. Furthermore, by optimizing HF-HNO₃The proportion of the system milling liquid ensures that the novel ultra-thin titanium foil chemical milling liquid has more stable performance.

The invention provides a chemical milling liquid for preparing an ultrathin titanium foil, which consists of the following components in part by weight: 15-25% of hydrofluoric acid solution, 1-3% of nitric acid solution, 5-8% of glacial acetic acid solution, 0.1-0.5 g/100mL of corrosion inhibition stabilizer of milling liquid and the balance of pure water.

Preferably, the chemical mass fraction of the hydrofluoric acid solution is 3%; the chemical mass fraction of the nitric acid solution is 63 percent; the chemical mass fraction of the glacial acetic acid solution is 99.5%. The corrosion inhibition stabilizer is one or more of polyacrylamide, polyvinyl alcohol and sodium silicate.

Among the three stabilizers, polyacrylamide is preferred, the effect is optimal, and a small amount of the stabilizer is effective; polyvinyl alcohol and sodium silicate are slightly less effective than polyacrylamide, and the three can also be mixed for use.

The second aspect of the invention provides a milling method for preparing an ultrathin titanium foil, which comprises the following steps:

1) degreasing and cleaning the surface of the titanium foil: ultrasonically dipping and washing the titanium foil to be treated in acetone, absolute ethyl alcohol and pure water for 5-10 min in sequence, and drying and taking out;

2) chemical milling: immersing the titanium foil treated in the step 1) in the chemical milling liquid for 1-4 min for milling;

3) surface cleaning: and sequentially soaking and washing the milled titanium foil in acetone and pure water for 6-10 min.

Preferably, in the step 1), the titanium foil to be treated is ultrasonically soaked and washed in an acetone solution for 3min to 5 min; ultrasonically soaking and washing in absolute ethyl alcohol for 1-3 min; ultrasonically soaking and washing in pure water for 1-3 min. The drying condition is that the mixture is placed in a drying oven with the temperature of 80-100 ℃ for 10-15 min.

Preferably, in step 2), slight ultrasonic vibration is performed while the chemical milling is performed.

Preferably, in the step 3), the titanium foil is soaked and washed in an acetone solution for 3min to 5min and in pure water for 3min to 5 min.

The invention has the following beneficial effects:

firstly, the addition of the corrosion inhibition stabilizer improves the viscosity of the chemical milling liquid, reduces the diffusion rate of ions, further reduces the milling rate during milling, avoids the occurrence of the condition of titanium foil surface over-corrosion caused by exponential increase of the later milling rate, contributes to improving the stability of the milling liquid, and ensures efficient and stable milling. Experiments prove that the chemical milling liquid added with the stabilizing agent has uniform milling, can obviously relieve the wrinkling phenomenon of the surface of the titanium foil, has high stability, and is more suitable for processing ultrathin titanium foil soldering lugs.

Secondly, the chemical milling liquid has low price, high efficiency, stability and uniform milling, and can obviously relieve the wrinkling phenomenon of the surface of the titanium foil. Compared with rolled ultrathin titanium foils, the ultrathin titanium foil prepared by the method disclosed by the invention is low in cost, can meet the quality requirement of a copper-clad ceramic substrate on a titanium foil soldering lug, is beneficial to reducing the preparation cost of the titanium foil, and further reduces the preparation cost of the AMB copper-clad plate.

Drawings

FIG. 1 is a flow chart of the present invention for preparing an ultra-thin titanium foil;

FIG. 2 is a comparison of the surface state of a titanium foil milled according to the present invention with that of a titanium foil milled by a conventional method, wherein (a) is an ultra-thin titanium foil prepared in example 1 and (b) is an ultra-thin titanium foil prepared in comparative example 1;

fig. 3 is a schematic diagram of the selected position of the copper-ceramic peel strength test strip.

Detailed Description

The following embodiments are implemented on the premise of the technical scheme of the present invention, and give detailed implementation modes and specific operation procedures, but the protection scope of the present invention is not limited to the following embodiments.

The reagents and starting materials used in the present invention are commercially available or can be prepared according to literature procedures. The experimental procedures, in which specific conditions are not noted in the following examples, are generally carried out according to conventional conditions or according to conditions recommended by the manufacturers.