PCBA Tech - Explore the related equipment required for SMT processing

SMT chip processing plant said that there are many equipment required for SMT chip processing, such as: solder paste printer, placement machine, reflow soldering, AOI detector, etc.; in addition, if the bare hand touches the board, it may cause green oil Adhesion becomes poor, air bubbles fall off, etc.

SMT chip processing plant said that there are many equipment required for SMT chip processing, such as: solder paste printer, placement machine, reflow soldering, AOI detector, etc.; in addition, if the bare hand touches the board, it may cause green oil Adhesion deteriorates, bubbles fall off and other influences; then I will introduce the relevant content in detail.

1. Equipment required for SMT patch processing

1. PCBA solder paste printing machine

Modern solder paste printers generally consist of plate loading, solder paste addition, imprinting, and power transmission substrates. The working principle is to first fix the printed circuit board on the printing positioning table, and then use the left and right scrapers of the printer to leak the solder paste and red glue to the corresponding pads through the stencil, and then input the evenly leaked PCB through the transmission table. The placement machine performs automatic placement.

2. Mounter

Mounter: also known as Mounter, Surface Mount System (Surface Mount System), after the cream printing machine is configured on the production line, it is the production equipment for correctly configuring the surface mounter through the mobile mounter. According to installation accuracy and installation speed, it is usually divided into high speed and normal speed.

3. Reflow soldering

There is a heating circuit inside the reflow soldering. After heating the air and nitrogen to a high enough temperature, blow it to the PCB board where the parts are already attached, so that the solder on both sides of the parts is melted and then bonded to the main board. The advantages of this process are that the temperature is easy to control, oxidation can also be avoided during welding, and the production and processing costs are also easy to control.

4. AOI detector

The full name of AOI is the utomaticOptic principle of production equipment that detects common defects in welding production. AOI is an emerging test technology, but it is developing rapidly, and many manufacturers have introduced AOI test equipment. During automatic inspection, the machine automatically scans the PCB through the camera, collects images, compares the tested solder joints with the qualified parameters in the database, detects the defects of the PCB through image processing, and displays the defects/displays on the display or automatically, and the maintenance personnel repair them.

5. Parts trimming machine

For cutting feet and deformed pin parts.

6. PCBA wave soldering

Peak welding is to make the welding surface of the plug-in board directly contact high-temperature liquid welding to achieve the purpose of welding. The high-temperature liquid welding maintains an inclined plane. Because of the special device that makes the liquid welding form a wave-like phenomenon, it is called peak welding. Its main material is a welding rod. .

2. The impact of bare-hand operation on SMT patch processing

1. The bare-hand touch panel before resistance welding will cause resistance welding, resulting in poor adhesion of the green oil, and hot air usually blisters and falls off.

2. The bare object contacting the board will cause a chemical reaction on the copper surface of the board in a very short time, and the copper surface will be oxidized. If the time is a little longer, there will be obvious fingerprints after electroplating, the coating is not smooth, and the appearance of the product is seriously bad.

3. There are fingerprint grease on the PCB printed wet film and silk screen printed circuit and the board surface before lamination, which is easy to reduce the adhesion of the dry/wet film, the plating layer and the plating layer are separated during electroplating, and the gold plate is easy to cause the surface pattern to complete the resistance welding. The back surface is oxidized, showing a yin and yang color.

4. During the process from the solder mask to the packaging of the PCB gold board, touching the board surface with bare hands will cause the circuit board surface to be dirty, poor PCB solderability or poor bonding.