PCBA Tech - SMT steel mesh use method and environmental requirements

How to use steel mesh in SMT patch processing

In SMT patch processing and reflow soldering, SMT steel mesh is an indispensable important tool. In addition to the use effect of the steel mesh, users are also concerned about the service life of the steel mesh. Last time, Jingbang technicians also shared the SMT steel mesh production specifications and precautions. Today, I will mainly organize and introduce the use and maintenance methods of SMT steel mesh, which can effectively extend the service life of the steel mesh.

1. Handle with care to avoid collision

In order to avoid damaging the SMT steel mesh, please handle it gently during use. Do not hit the steel mesh with hard objects or sharp knives.

2. Keep the SMT steel mesh clean

1. The steel mesh should be cleaned (wiped) before use to remove the dirt carried during transportation and avoid affecting the use effect.

2. The steel mesh should also be cleaned in time after use, returned to the packing box, and placed in a dedicated shelf upright. It should be noted that the boards should be isolated from each other (film can be pasted), and it is forbidden to overlap and contact each other.

3. The steel mesh waiting to be cleaned should not be placed randomly to avoid accidental damage.

Third, use SMT steel mesh correctly

1. Stir the solder paste or red glue evenly to avoid clogging the steel mesh.

2. Adjust the printing pressure to the best, the best pressure is when the squeegee can just scrape off the solder paste (red glue) on the stencil.

3. After the scraper stroke is completed, if possible, it is best to stop for 2 to 3 seconds before demolding, and the demolding speed should not be too fast.

Fourth, control the number of uses of SMT steel mesh

Generally speaking, the use times of SMT steel mesh can reach 100,000 times, and it is forbidden to use the steel mesh for an extended period of time. The steel mesh that exceeds the service life should be scrapped, and effective methods need to be used for monitoring.

2. Environmental requirements during SMT patch processing

What are the environmental requirements for SMT chip processing? Many customers come to visit the SMT patch processing site will have such doubts

The SMT chip processing society is a kind of high-precision equipment, which requires many external environmental conditions, such as cleanliness, humidity, and temperature. In order to allow the equipment to work normally, reduce equipment loss due to environmental factors, and improve product quality, the SMT patch processing location has the following requirements:

The following requirements:

1. The power supply generally requires single-phase AC220 (220±10%, 0/60Hz), three-phase AC380 (380±10%, 50/60Hz), and the power of the power supply should be more than twice the power consumption.

2. The air source is configured with the pressure of the air source according to the requirements of the equipment. The air source of the factory can be used, or it can be equipped with an oil-free compact air machine. The ordinary pressure is greater than 7kg/cm2. Clean and dry polluted air is required, so it is necessary to stop the deoiling, dusting, and water treatment of the compressed air. Use stainless steel or pressure-resistant plastic pipes for air ducts.

3. Exhaust fans are required for exhaust air reflow soldering and wave soldering equipment. Regarding the full hot blast stove, the minimum flow rate of the exhaust duct is 500 cubic feet per minute (14.15m3/min)

4. The ambient temperature of the temperature and humidity production workshop is 23±3 degree Celsius, and the normal temperature is 17～28 degree Celsius, and the absolute humidity is 45%～70%RH. According to the size of the workshop, set a suitable thermometer and hygrometer, stop regular monitoring, and Equipped with equipment to adjust temperature and humidity.

5. Anti-static task personnel must wear anti-static clothing, shoes, and anti-static wristbands to enter the workshop. The anti-static task area should be equipped with anti-static air, anti-static seat cushions, anti-static packaging bags, turnover boxes, PCB racks, etc.