SMT components are extremely small and lightweight, and the SMT components are easier to solder than lead components. Another important benefit of the SMT component is that it improves the stability and reliability of the circuit, which increases the success rate of the production. This is because the SMT components have no leads, which reduces stray electric fields and stray magnetic fields, which is especially noticeable in high frequency analog circuits and high speed digital circuits.
Printing method of SMT processing:
1. Printing:
The thickness of SMT steel stencil and the size and shape of the engraving hole should be determined according to the type of the components and the performance of the PCB board's CCL. The advantages are speed and efficiency.
2. Gluing:
gluing is the use of compressed air, the red glue through the special dispensing head point to the PCB board, the size and amount of the glue point are controlled by time and pressure tube diameter, the dispenser is flexible. For different components, we can use different dispensing heads and set different parameters, also can change the shape and number of glue points to achieve the effect, the advantages are convenient, flexible and stable. The disadvantage is that it is easy to have spinning and air bubbles. We can minimize these shortcomings by adjusting the operating parameters, speed, time, pressure, and temperature.
3. Needling:
The needling is to immerse a special needle film in a shallow glue disc. Each needle has a glue point. When the glue point contacts the PCB board, the glue will be separated from the needle. The amount of glue can be changed by the shape and diameter of the needle. Cure temperature 100 ° C 120 ° C 150 ° C, cure time 5 minutes 150 seconds 60 seconds Typical cure conditions: Note:
1) The higher the cure temperature and the longer the cure time, the stronger the bonding strength.
2) Since the temperature of the PCB SMT glue with the size and placement of the PCB components, we recommend finding the most suitable hardening conditions. Storage of red glue: It can be stored for 7 days at room temperature, more than 6 months at less than 5 °C, and stored for more than 30 days at 5-25 °C. Because SMT red glue is affected by temperature, and it has its own characteristics of viscosity, fluidity, wetting, etc. Therefore, SMT patch red glue must have certain conditions of use and standard management.
