Lead-free printed circuit board copper surface protecting agent and preparation method thereof

Abstract

The invention discloses a lead-free printed circuit board copper surface protecting agent and a preparation method thereof. The lead-free printed circuit board copper surface protecting agent is a mixture prepared by the following materials with parts by weight: 1-15 parts of organic acid, 0.1-2 parts of metal salt, 0.1-3 parts of imidazoles compound, 0.01-0.15 part of non-ionic surfactant and 79.85-98.79 parts of deionized water. The invention also provides a preparation method of the protecting agent and is applied to the naked copper surface processing technology of the printed circuit board (PCB) of electronic industries. The protective film generated after the dipping treatment of the protecting agent has flat, non-crispy, anti-oxidation, heat shock resistant and humidity resistant properties. The invention has low production cost, simple production process, convenient and quick use and extremely broad market shares.

Description

Technical field [0001] The invention relates to a copper surface protective agent, in particular to a lead-free printed circuit board copper surface protective agent and a preparation method thereof. Background technique [0002] In July 2006, the EU "Directive on the Prohibition of the Use of Certain Hazardous Substances in Electronic and Electrical Equipment" was formally implemented, marking the global electronics industry entering the era of lead-free soldering. The copper surface treatment method of printed circuit board (PCB) used in the electronics industry is generally to add a lead-free protective layer on the copper surface, such as immersion silver layer, immersion gold layer, electroless nickel plating, gold plating, pure tin plating, lead-free hot air Leveling, impregnating copper surface protective agent, etc., are designed to ensure that the PCB has good wettability and the solder joints are firm and reliable during the assembly and soldering process of electronic ...

AI Technical Summary

Problems solved by technology

[0003] Immersion silver, immersion gold, nickel plating, gold plating and other processes cost more and are mostly used in high-end and military electronic control equipment. Although pure tin plating is more economical, the process of pure tin plating is also a lead-free, halogen-free and environmentally friendly process that meets the needs of the green era. At present, Compared with tin-lead alloys, it is difficult to control the process, and the abnormal plating parameters often lead to tin deficiency, which directly affects the quality of PCB.

The hot air leveling production technology is a traditional process widely used in the PCB industry due to its relatively economical and reasonable production cost and process. A thin layer of tin alloy protection is formed on the flat PCB surface (including through holes). Due to the requirements of lead-free environmental protection, the furnace temperature required by the lead-free hot air leveling process needs to be increased, and the amount of hot air is also increased. This is because the tin-lead alloy The melting point of tin is 183°C, and the dipping temperature is about 250°C, while the melting point of pure tin is 231°C, and the dipping temperature is about 270°C. Defects such as poor precision, especially for thin PCBs with low rigidity, it is not suitable for hot air leveling process

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