PCB Technical - PCBA patch and SMT patch processing requirements

What are the requirements for PCBA patch processing and SMT patch processing, mainly the following points, for reference:

With the development of electronic products in the direction of miniaturization, the size of SMT 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. The SMT patch factory with efficient operation and good quality control, in addition to strict control of the process flow, 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 patch 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 the equipment, reduce environmental damage to components and improve quality, 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. Exhaust

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

3. Temperature and humidity

The ambient 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.

4. Air source

According to the requirements of the equipment, the pressure of the air source can be configured. 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 de-oiled, Dust and water treatment. Use stainless steel or pressure-resistant plastic pipes for air ducts.

5. Anti-static

Workers need to wear anti-static clothing, shoes, and anti-static bracelets to enter the workshop. 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, if it is not used immediately, it needs to be placed in the refrigerator for refrigeration. The temperature is best to be 5 degree Celsius-10 degree Celsius, not lower than 0 degree Celsius. There are many explanations on the stirring and use of solder paste on the Internet, here is Not much introduction.

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 of machine equipment, it is necessary to carefully check whether the suction nozzle is blocked or damaged, and whether the feeder is intact.

3. Measuring furnace temperature

The quality of PCB circuit board soldering has a great relationship with the reasonable setting of the process parameters of reflow soldering. Generally speaking, the furnace temperature test needs to be performed twice a day, and the minimum test is once a day to continuously improve the temperature curve., Set the temperature curve that best fits the welding product. Don't miss this link for the sake of production efficiency and cost saving.