阅读说明：本技术 一种印制电路板的制备方法 (Preparation method of printed circuit board ) 是由 赵经纬 聂锋 刘培培 于 2020-05-29 设计创作，主要内容包括：本发明公开了一种印制电路板的制备方法,包括如下步骤：将铜浆通过印刷在基板上形成图案后干燥,得到有铜粉图案的印制电路板；在非氧化性气氛保护下,将有铜粉图案的印制电路板通过高频电磁感应加热,铜粉熔化互相粘连形成一体化图案的铜层,本发明的制备方法通过高频电磁震荡的方式,使得铜粉在短时间内融化,形成完整的线路铜层,同时作为基材的陶瓷基板几乎不受到热冲击而产生碎裂风险,烧结时间短,能量投放准确,可以降低保护气氛要求,所形成的金属铜层具有清晰度优良、氧化程度低、电导率好的特点。(The invention discloses a preparation method of a printed circuit board, which comprises the following steps: printing copper paste on a substrate to form a pattern, and drying to obtain a printed circuit board with a copper powder pattern; under the protection of a non-oxidizing atmosphere, a printed circuit board with copper powder patterns is heated through high-frequency electromagnetic induction, the copper powder is melted and adhered to form a copper layer of an integrated pattern, the copper powder is melted in a short time through a high-frequency electromagnetic oscillation mode, a complete circuit copper layer is formed, meanwhile, a ceramic substrate serving as a base material is hardly subjected to thermal shock to generate a fracture risk, the sintering time is short, the energy input is accurate, the requirement of a protective atmosphere can be lowered, and the formed metal copper layer has the characteristics of being excellent in definition, low in oxidation degree and good in conductivity.)

1. A method for preparing a printed circuit board is characterized by comprising the following steps:

(1) printing copper paste on a substrate to form a pattern, and drying to obtain a printed circuit board with a copper powder pattern;

(2) under the protection of non-oxidizing atmosphere, the printed circuit board with the copper powder pattern is heated through high-frequency electromagnetic induction, and the copper powder is melted and mutually adhered to form a copper layer with an integrated pattern.

2. The method for manufacturing a printed circuit board according to claim 1, wherein: the induction heating frequency is 500KHz-2000 KHz.

3. The method for manufacturing a printed circuit board according to claim 1, wherein: the induction heating time is 10 seconds to 10 minutes.

4. The method for manufacturing a printed circuit board according to claim 1, wherein the copper paste comprises the following raw material components: the copper powder, the deionized water and the auxiliary agent are in a mass ratio of 50-80:20-50:0.05-15, the auxiliary agent comprises a binder, a rheological agent or an antioxidant, and the mass ratio of the binder, the rheological agent or the antioxidant is 0.05-5:0-10: 0-5.

5. The method for manufacturing a printed circuit board according to claim 4, wherein: the binder is one or more of carboxymethyl cellulose, carboxymethyl cellulose salt, hydroxymethyl cellulose salt, polyvinyl alcohol, polyacrylate or water-soluble copolymer of acrylate.

6. The method for manufacturing a printed circuit board according to claim 4, wherein: the rheological agent is one of ethanol, acetone, methanol, isopropanol, glycerol, polyethylene glycol or polysiloxane.

7. The method for manufacturing a printed circuit board according to claim 1, wherein: the non-oxidizing atmosphere is an argon atmosphere or a hydrogen atmosphere.

8. The method for manufacturing a printed circuit board according to claim 1, wherein: the substrate is a ceramic substrate.

9. The method for manufacturing a printed circuit board according to claim 8, wherein: the ceramic substrate is a flat material with the thickness of 0.2-5mm and sintered by one or more of silicon oxide, aluminum nitride, magnesium oxide and zirconium oxide.

10. The method for manufacturing a printed circuit board according to claim 1, wherein: the drying device is one of an oven, an infrared dryer or a microwave dryer.

Technical Field

The invention relates to a preparation method of a circuit board, in particular to a preparation method of a printed circuit board, and belongs to the field of electronic element preparation processes.

Background

Printed Circuit Boards (PCBs) are widely used in almost all electronic devices as a fundamental and important component of the modern electronics industry. At present, the printed circuit board is mainly prepared by an etching method, and the main principle is that a copper-clad plate is adopted as a raw material, under the protection of photosensitive resin, oxidizing etching liquid is used, the copper foil of the unnecessary part is etched and removed according to the requirements of a circuit design drawing, a basic circuit is formed, then a series of chemical and physical treatments are carried out, and components are welded, so that the functional circuit board is formed. The above process is to remove the excess copper layer on the complete copper layer by etching to form the designed circuit pattern, and is therefore also called subtractive process.

In the process, the etching process is a process which has serious influence on the environment and human body, the main component of the etching liquid is liquid consisting of an oxidant and dilute acid, a large amount of copper ions are added into the waste liquid after etching, and the post-treatment difficulty of the waste liquid is very high. In the treatment process, corrosive acid mist can be generated to influence equipment, personnel and environment, and meanwhile, the etched copper-clad plate needs to be cleaned by a large amount of water to remove etching liquid and also generates a large amount of metal ion acidic waste liquid.

Therefore, the conventional PCB production, as a highly polluted industry, is subject to various degrees of restrictions in various regions, and the restrictions tend to be more and more severe as social development and environmental protection are increased.

In contrast to the subtractive process, the sintering of the powder material allows the direct formation of lines on the blank substrate as required by the design, a process known as additive. Sintering is a process of depositing metal powder in a desired pattern (typically by printing with a metal paste) and then thermally fusing the powder together to form a complete conductive path.

At present, the process is generally applied to the production of thick film circuits, and conductive paste is prepared by adopting powder of noble metals such as silver, palladium and the like, and dispersing agent, auxiliary agent and the like for circuit printing. Because the production cost is high, the method can only be applied to the fields of thick film circuits with small area and high added value, and is difficult to be applied to printed circuit boards with sensitive cost on a large scale. If the application range of the process needs to be expanded, expensive noble metals such as gold, silver and platinum are inevitably replaced by cheap materials such as copper and aluminum. However, copper and aluminum, although inexpensive, are prone to oxidation problems during high temperature sintering, and, if light, reduce conductivity, and if heavy, completely oxidize and cannot be used, so strict atmosphere protection is required to cope with metal oxidation during long temperature ramp-up and ramp-down.

Meanwhile, the traditional box furnace or tunnel furnace is adopted for sintering metal powder, a longer temperature rise and drop process is needed to reduce thermal shock to the ceramic substrate, a large amount of heat is used for heating the ceramic substrate and dissipating the ceramic substrate instead of heating the metal to be melted clearly, and the process is high in energy consumption and low in production efficiency.

Disclosure of Invention

The purpose of the invention is as follows: the invention aims to provide a method for preparing a printed circuit board, which has the advantages of short heating time, high production efficiency, small copper layer oxidation and greatly improved economical efficiency and product quality.

The technical scheme is as follows: the preparation method of the printed circuit board comprises the following steps:

(1) printing copper paste on a substrate to form a pattern, and drying to obtain a printed circuit board with a copper powder pattern;

(2) under the protection of non-oxidizing atmosphere, the printed circuit board with the copper powder pattern is heated through high-frequency electromagnetic induction, and the copper powder is melted and mutually adhered to form a copper layer with an integrated pattern.

Further, the copper paste is prepared from the following raw material components: copper powder, deionized water and an auxiliary agent, wherein the mass ratio of the copper powder to the deionized water to the auxiliary agent is 50-80:20-50:0.05-15, the auxiliary agent comprises a binder, a rheological agent or an antioxidant, and the mass ratio of the binder to the rheological agent or the antioxidant is 0.05-5:0-10: 0-5.

Preferably, the binder is one or more of carboxymethyl cellulose, carboxymethyl cellulose salt, hydroxymethyl cellulose salt, polyvinyl alcohol, polyacrylate or water-soluble copolymer of acrylate. The rheological agent is one of ethanol, acetone, methanol, isopropanol, glycerol, polyethylene glycol or polysiloxane.

Further, the induction heating frequency is 500KHz-2000 KHz. The induction heating time is 10 seconds to 10 minutes.

Preferably, the non-oxidizing atmosphere is an argon atmosphere or a hydrogen atmosphere, and the non-oxidizing atmosphere is a gas atmosphere provided to prevent substantial oxidation of the copper powder during sintering.

The substrate is a ceramic substrate, and the ceramic substrate is a flat plate-shaped material with the thickness of 0.2-5mm and sintered by one or more of silicon oxide, aluminum nitride, magnesium oxide and zirconium oxide. The drying device is one of an oven, an infrared dryer, or a microwave dryer.

Has the advantages that: compared with the prior art, the invention has the following remarkable advantages: the invention provides a method for directly and locally heating the metal copper powder on the printed circuit board by adopting a high-frequency induction mode aiming at the process characteristics of producing the printed circuit board by a powder sintering method, and the heating principle of a high-frequency induction furnace is that induced current is generated in metal by adopting high-frequency electromagnetic oscillation, so that thermal shock is hardly generated on a ceramic substrate except for a metal circuit pattern, the energy utilization rate is very high, and the method is very suitable for sintering the printed circuit board; the method for sintering the printed circuit board has the advantages of short heating time, high production efficiency, small copper layer oxidation and great improvement on economy and product quality.

Detailed Description

The technical solution of the present invention is further illustrated by the following examples.