1) Single-sided mounting process
2) Double-sided mounting process
3) Single-sided mixed process
4) Double-sided mixed process
3. Several steps to enhance SMT equipment governance:
1. SMT line construction plan design
The principles of line construction are shared use, cost-effectiveness, and expandability. To align with the purpose of SMT use, the nature and type of products produced, the size and accuracy of components and ICs, the type and number of components, the size of the P board required, production scale, and batch quality level requirements must be considered. This will help determine the appropriate device model.
Scalability must be considered. Due to the rapid development of the electronic product and its supporting component industry, SMT equipment must have room for system functionality, accuracy, indicator expansion, and production capacity improvement. Choosing the latest equipment and purchasing all options at once will inevitably lead to overinvestment, and many unsuitable devices may remain idle for many years, causing significant capital pressure and economic losses. In order to establish a well-equipped and powerful SMT production line, some small and medium-sized enterprises must bear the corresponding problems, as large investment and short cycle equipment replacement will bring difficulties. If the application effect on the purchased device is not satisfactory, it will impose a heavy burden on the company. Therefore, when designing and constructing production lines, the choice of economic use is a key point. Although high-speed engines are fast and powerful, their price is about 2 to 3 times that of medium speed engines. If there are not many types of products produced and the output is large, several medium speed production lines can be chosen to solve the problem of one-time large investment, while using small investments for multiple investments can flexibly improve production capacity. After equipment failure, efforts should be made to minimize its impact. The best payback period for equipment investment is 2-3 years.
2. What types of solder paste are used in SMT surface mount processing?
In the SMT surface mount processing, there are various types of solder paste, and it is necessary to choose the appropriate solder paste according to the processed product. The following editor will introduce this.
1. Lead containing solder paste and lead-free solder paste
Lead containing solder paste contains lead, which is harmful to the environment and human health, but its welding effect is good and the cost is low. Suitable for certain electronic products that do not require environmental protection. Lead free solder paste contains a small amount of lead, which is less harmful to human health and is an environmentally friendly product commonly used in environmentally friendly electronic products. Foreign customers usually require the use of lead-free solder paste for production.
2. High temperature solder paste, medium temperature solder paste, low temperature solder paste
1. High temperature solder paste is a commonly used lead-free solder paste, with a melting point generally above 217 ° C and good soldering effect.
2. Medium temperature solder paste. The commonly used lead-free medium temperature solder paste has a melting point of about 170 ° C. The main feature of medium temperature solder paste is the use of imported special rosin, which has good adhesion and effectively prevents collapse.
3. The melting point of low-temperature solder paste is 138 ° C, mainly containing bismuth. When surface mount components cannot withstand temperatures above 200 ° C and require reflow soldering, using low-temperature solder paste for soldering can protect the original components and PCBs that cannot withstand high-temperature reflow soldering, which is very popular in the LED industry.
3. Tin powder particle size
According to the particle size of tin powder, solder paste can be divided into grades 1, 2, 3, 4, 5, and 6. Among them, grade 3, 4, and 5 powders are the most commonly used. The higher the precision of the product, the smaller the required tin powder, but the smaller the tin powder, the larger the oxidation area of the tin powder. In addition, the circular shape of tin powder helps improve printing quality. The higher the difficulty of SMT surface mount processing, the more important the selection of solder paste. Only solder paste that meets product requirements can effectively reduce quality defects in solder paste printing, improve the quality of reflow soldering, and reduce production costs.
