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Dispensing and welding technology of SMT dispenser
PCBA Tech
Dispensing and welding technology of SMT dispenser

Dispensing and welding technology of SMT dispenser

2021-11-11
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Author:Downs

The dispensing method of the dispenser in the production and processing of SMT patches

In the production and processing of SMT patches in electronic processing plants, there are some relatively special electronic components that cannot only use the usual solder paste soldering process. This is because of their particularity. The usual solder paste soldering process will cause them to be There will be some problems that affect the use and longevity. Under normal circumstances, in SMT production and processing for this kind of SMT chip components will use some special processing measures, such as dispensing technology.

In SMT patch production and processing, dispensers are usually divided into manual and automatic two types, which are different for small batch and mass production. The most important part of the dispenser is the dispensing head.

Dispensing heads can be divided into four types according to the different distribution pumps: time pressure type, screw pump type, linear positive displacement pump type, jet pump type, etc. The four types of dispensing heads are briefly introduced below.

pcb board

1. Time-pressure dispensing head.

In the minds of many people, the pneumatic pump has always been the most direct way of dispensing in SMT production and processing. It uses the time pressure principle to use the compressor to generate a controlled pulse air flow to start the operation. The longer the airflow pulse action time during operation, the more the proportion of coating raw materials pushed out from the needle.

2. Screw pump type dispensing head.

The screw pump dispensing head has strong flexibility and is suitable for dispensing various patch glues. It is not sensitive to the air mixed in the patch glue, but is sensitive to changes in viscosity. The dispensing speed also affects the consistency of the dispensing.

3. Linear positive phase displacement dispensing head.

The linear positive phase displacement glue head has good glue dot consistency during high-speed dispensing, can dispense large glue dots but is complicated to clean, and is sensitive to air in the patch glue.

4. Jet pump type dispensing head.

The jet pump type is a non-contact dispensing head, which has a fast dispensing speed and is not sensitive to PCB warpage and height changes. However, the large glue dot speed is relatively slow, requiring several sprays, and cleaning is complicated.

3 common soldering techniques in smt patch processing

The three common soldering techniques in smt patch processing are wave soldering technology, reflow soldering process and laser reflow soldering process.

1. Wave soldering technology for smt chip processing. The wave soldering technology mainly uses SMT steel mesh and adhesive to firmly fix the electronic components on the printed circuit board, and then uses the wave soldering equipment to solder the circuit board patch immersed in the molten tin. This type of welding technology can realize the double-sided processing of the patch, which helps to further reduce the volume of electronic products. However, this type of welding technology has the defect that it is difficult to achieve high-density patch assembly processing.

2. Reflow soldering technology for smt chip processing. The reflow soldering technology is based on the SMT steel mesh of the appropriate specification and model, and the solder paste is printed on the electrode pads of the electronic components temporarily, so that the electronic components are temporarily set in their respective positions, and then according to the reflow soldering machine, each lead The solder paste on the feet melts and flows again, fully infiltrating the electronic components and circuits on the patch, and solidify it again. The reflow soldering technology of SMT processing is simple and fast, and it is a commonly used soldering technology in SMT chip processing manufacturers.

3. Laser reflow soldering technology for smt chip processing. The laser reflow soldering technology is generally the same as the reflow soldering technology. The difference is that laser reflow soldering uses a laser to directly heat the soldering position, causing the solder paste to melt and flow again. When the laser stops irradiating, the solder condenses again to form a stable and reliable solder connection. This type of method is faster and more accurate than the former, and can be regarded as an improved version of reflow soldering technology.