PCBA Tech - Requirements and precautions in SMT patch processing

With the development of electronic products in the direction of miniaturization, the size of chip components is getting smaller and smaller, and the requirements for processing environment of Mingo components are also becoming higher, which puts forward higher requirements for SMT chip processing. As an SMT chip factory with efficient operation and good quality control, in addition to strictly controlling the process flow, it also needs to strictly control the environment of the SMT workshop and clearly understand some precautions.

1. Environmental requirements of SMT patch processing workshop

SMT production equipment is a high-precision mechatronics equipment. The equipment and process materials have certain requirements for the cleanliness, humidity and temperature of the environment. In order to ensure the normal operation of equipment, reduce environmental damage to components, and improve quality, the SMT workshop environment has the following requirements:

1. Power

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

2. Air source

The pressure of the air source is configured according to the requirements of the equipment. The air source of the factory can be used, or an oil-free compressed air machine can be configured separately. Generally, the pressure is greater than 7kg/cm2. Clean and dry purified air is required, so the compressed air needs to be degreasing, dusting, and water removal treatment. Use stainless steel or pressure-resistant plastic pipes for air ducts.

3. Exhaust

Reflow soldering and wave soldering equipment need to be equipped with exhaust fans. For all hot blast stoves, the minimum flow rate of the exhaust duct is 500 cubic feet per minute (14.15m3/min)

4. Temperature and humidity

The environment temperature of the production workshop is 23±3 degree Celsius, which is generally 17～28 degree Celsius, and the relative humidity is 45%～70%RH. According to the size of the workshop, a suitable temperature and humidity meter is set up for regular monitoring and equipped with temperature adjustment. Humidity facilities.

5. Anti-static

Workers must wear anti-static clothing, shoes, and anti-static bracelets to enter the workshop. The anti-static work area should be equipped with anti-static floor, anti-static seat cushion, anti-static packaging bag, turnover box, PCB rack, etc.

Two, SMT patch processing matters needing attention

1. Solder paste refrigerated

The solder paste has just been bought, and if it is not used immediately, it needs to be placed in the refrigerator for refrigeration. The temperature should preferably be between 5°C and 10°C, not lower than 0°C. There are many explanations on the mixing and use of solder paste on the Internet, so I won’t introduce them here.

2. Replace the wearable parts of the placement machine in time

In the placement process, due to the aging of the placement machine equipment and the damage of the suction nozzle and feeder, it is easy to cause the placement of the placement machine to be crooked, and cause high throwing, reducing production efficiency and increasing production costs. In the case that the placement machine equipment is not available, carefully check whether the suction nozzle is blocked or damaged, and whether the feeder is intact.

3. Measuring furnace temperature

The quality of PCB board soldering has a great relationship with the reasonable setting of process parameters of reflow soldering. Generally speaking, the furnace temperature test needs to be carried out twice a day, at least once a day, in order to continuously improve the temperature curve and set the temperature curve that best fits the welding product. Don't miss this link for the sake of production efficiency and cost savings.