Analysis of the Application of Lead-free Environmentally Friendly Solder Paste in pcb Circuit Boards

At present, many companies choose itLead-free flux pasteProducts and processing techniques, then lead-free environmentally friendly solder paste, as an important part of lead-free processing techniques, its performance characteristics are increasingly attracting our attention. The following is based on the product research and development of lead-free ring solder paste, and some problems arising from lead-free processing techniques, such as alloy selection We will delve into aspects such as printability, ultra-low temperature reflux, and cavity level. Meanwhile, today, the editor of JJY will introduce to you the corresponding features of the new generation of lead-free solder paste products.

1.Printability

BecauseSn/Ag/CuThe relative density of the alloy(7.5g/mm3)thanSn-PbThe relative density of the alloy(8.5g/mm3)The printing performance of lead-free solder paste using this alloy is slightly worse than that of leaded solder paste,Such as it is very easy to stick to the scraper, etc. Even so, because ensuring the better printability of the solder paste is aimed at improving SMTProductivity and cost control are of great significance. Under the condition that the alloy composition is the same, only by adjusting the composition of the solder paste can it be improved The printability of solder paste, such as the ability to fill mesh, wet compressive strength, and cold resistance/The working capacity in thermal collapse and damp and cold natural environments, etc., and thereby be enhanced Printing speed and improvement of the actual printing effect.

2.The necessity of flowing back

Because the melting point of lead-free alloys rises.Sn/Ag/CuThe melting point of the alloy is217°C,Sn-PbThe melting point of the alloy is183°CThe main problem encountered by lead-free processing technology is the increase of the maximum temperature in the reflow soldering furnace . When lead-free environmentally friendly solder paste flows back into the electric soldering, under the worst-case assumption (pcbThe circuit board is the most complex. The system deviation and data error are positive, and it is necessary to reach the standard of sufficient moisture.pcbThe temperature at which the network hotspot on the circuit board is most likely to be achieved.265°C"

3.Selection of alloys 

In order to better find suitable lead-free alloys to replace the traditional onesSn-PbAlloys, many attempts have been made by everyone. This is because there are many factors to consider when choosing lead-free alloys, such as melting point, impact toughness, shelf life, and cost.

4.Hollow level

Voids are a common defect in flow back welding, especially in the pastBGA/CSPThe presentation on electronic devices is particularly prominent. Due to the significant differences in the size, location, proportion of cavities and their precise measurement fields, the safety assessment of cavity levels has not been unified so far.

Shenzhen CityJJYCarry out mutually beneficial cooperation with electronic raw material producers, and also produce solder wires, solder rods, solder pastes and flux pastes for other enterprises. With a rich variety of successful cases in the research and development of chemical raw materials, our overall strength has created a sales market that is of high quality and honest and trustworthy.