SMT process materials play a vital role in the quality and production efficiency of SMT, and are one of the foundations of the surface assembly process. When designing the SMT process and establishing the production line, appropriate process materials must be selected according to the process flow and process requirements. What are the requirements for choosing the right process material? Let’s take a look at the following Sanjing belts:

First of all, the first point is to have good stability and reliability. The content of harmful impurities is strictly controlled for solder, low residue and non-corrosive for solder paste and flux; moderate bonding strength is required for bonding agent to ensure that the chip does not fall during the soldering process and is convenient to peel off during maintenance.

The second is to meet the needs of high-speed production. The SMT production process is generally a high-speed automated process, and the process materials should be adapted to it. For example, the curing time of the adhesive is about 20 minutes in the oven intermittent curing method, and the continuous curing method in the tunnel furnace requires the curing time to be within 5 minutes. Therefore, it is required to shorten the curing time.

The third is to meet the needs of fine pin pitch and high-density assembly. Fine pin spacing and high-density assembly require the alloy solder powder in the solder paste to have finer particle size, better thixotropy of the solder paste and bonding agent, and smaller slump. It requires strict control of the solid content and activity in the flux to avoid Defects such as bridging have occurred.

The last point is also very important, that is, to meet environmental protection requirements. Many materials in the traditional SMT process materials contain substances harmful to the ozone layer of the atmosphere and the human body, such as some lead-containing solders. At present, solder is divided into lead-free and lead-free according to the amount of lead, and lead-free solder has gradually been replaced by lead-free solder.

Lead-free solder is characterized by high melting point, superior tensile strength, and strong fatigue resistance. It has higher requirements for the thermal stability of the flux and the soldering process and equipment. With the strengthening of human environmental protection awareness and increasing attention to human health, The harmless SMT process materials are being produced and popularized continuously.

The above is about the requirements of the assembly process materials in the SMT process, I hope it can be helpful to everyone!