PCBA Tech - SMT refueling process and heat transfer of welding electrodes

SMT chip processing and refueling process

Open the feed inlet, and then remove the paper tray.

SMT patch processing operators can take materials from the rack according to their working position, or take materials according to their working position.

The operator should check according to the job number table to ensure that the specifications and models are consistent.

The operator should check the old and new accessories to ensure that their specifications and models are exactly the same.

Fifth, the operator should check whether the materials meet the requirements of the enterprise.

If the above abnormal situation is found, the operator should immediately notify the delay in handling.

Use new metal and place it on top of new or old metal.

Feida's new materials should be posted on the refueling process record sheet, and relevant data should be filled in, such as refueling man-hours, operator management, etc.

Install the feeder into the patch machine according to the patch machine position; the patch must be completed at one time.

The engineering quality management personnel understand the material ratio and testing, as well as the necessity of material change and inspection.

IPQC checks whether the site data is generated correctly and whether the site is established normally according to the site number table.

The above-mentioned placement machine has been checked for operation before production.

The above-mentioned 12 steps are standard procedures that must be strictly followed during the entire reloading process. Each link has operating procedures. Only in this way can errors in reloading be avoided.

Heat transfer method of welding electromechanical electrode processing in SMT chip processing

The SMA welding process is used to analyze the surface composition of the weldment and divide it into far-infrared welding, all-hot-air welding, and infrared/hot-air welding. The welding machine is also called spot welding, spot welding or spot welding furnace.

Now I want to introduce to you the heat conduction method in the processing of T-shaped welding electrodes, Shanghai SMT chip processing!

Zero position, far infrared welding

The far-infrared welding machine used in the 1980s has the advantages of fast heating speed and stable operation. However, due to the different materials of the printed board, the radiant heat absorption energy of different solder joints is also very different, resulting in uneven temperature distribution in each solder joint and different parts of the circuit, that is, local solder joints. For example, the black plastic package of an integrated circuit will overheat due to high radiation absorption energy, and its color line soldering will produce low-temperature virtual soldering.

In addition, thermal radiation blocking parts on the printed board, such as solder pins with large beams (large beams) or small beams, will not be sufficiently heated, which will lead to poor soldering.

All secondary hot air welding.

All hot air welding is a welding method that uses hot air to blow the weldment into the nozzle or a high-temperature fan to achieve air circulation. This device has been produced since the 1990s. It makes the welding temperature of the circuit board and the welding machine close to the temperature of a certain heating temperature zone, completely overcomes the local heating effect and shielding effect of the infrared welding machine, and is a widely used welding method.

In circulating air welding equipment, the acceleration of circulating air is an important parameter. In order to ensure that the circulating gas acts on any area of the printed board, the airflow must have a fast speed to make the printed board easy to shake and shift. In addition, this heating method has a low heat exchange rate and high energy consumption.

Infrared hot air welding, based on an infrared heating furnace in 2003, added hot air to make the furnace temperature more uniform, which is currently an ideal heating method. Utilizing the characteristics of strong infrared penetrating ability, it can not only improve thermal efficiency, but also save electricity, and at the same time, it can overcome the local heat radiation and shielding effect of infrared, and make up for the excessive requirements of hot air welding machine for air flow speed. It is currently widely used hot air welding machine .

With the increase of SMT assembly density, gap assembly technology appeared, and nitrogen shielded welding furnace appeared. Nitrogen shielded welding can prevent oxidation, improve the wettability of PCB solder joints, have a large correction force for unevenness, reduce solder joints, and is suitable for no-cleaning process.