PCB Tech - Double-sided assembly of SMT patch processing

How much do you know about the process of SMT patch processing? SMT processing can be divided into two processes, one is a single-sided patch process, and the other is a double-sided patch process. These two process flows are still different. Take the single-sided assembly of SMT patches as an example., It is mainly carried out in the order of incoming inspection, silk-screen solder paste, patch, drying, reflow soldering, cleaning, inspection, and repair. There will be some misunderstandings during SMT chip processing, such as the inability to use soldering correctly!

There are two ways to complete the double-sided assembly of SMT patches, one is incoming material inspection, the A-side silk-screen solder paste of the PCB board, the B-side silk-screen solder paste of the patch PCB, patch, drying, reflow soldering, Cleaning, testing, and repairing, so the process is to complete the double-sided assembly of the SMT patch. Another incoming inspection of PCB's A side silk screen solder paste, patch, drying, A side reflow soldering, cleaning, flipping, PCB B side point patch glue, patch, curing, B side wave soldering, cleaning, Testing and repairing. This process is suitable for reflow soldering on the A side of the PCB and wave soldering on the B side. In the SMD assembled on the B side of the PCB, this process should be used when there are only SOT or SOIC pins below.

SMT chip processing

In addition, there are single-sided mixed assembly process and double-sided mixed assembly process. The former starts with the raw material inspection, and then the PCB A-side screen printing solder paste, patch, baking, reflow soldering, cleaning, plug-in, wave soldering, cleaning, and inspection, Repair and other steps.

The latter has more actual operation methods, which can be divided into five types. One is sticking first and then inserting, which is suitable for the situation where there are more SMD components than separate components; the opposite is the first inserting and then sticking, which is suitable for more separation components than separate components. In the case of SMD components, there are three types of A-side mixed mounting and B-side mounting; two-side SMD first, reflow soldering, then inserting, wave soldering; and A-side mounting and B-side mixed mounting to meet different SMT mounting Film requirements.

If the soldering force is increased, the heat conduction of the solder paste can be increased, thereby increasing the soldering tin. But the actual situation is just the opposite. If the applied soldering force is too large, it is easy to cause defects such as warping, delamination, and depression of the pads of the patch. In fact, the correct approach is to gently touch the soldering iron tip to the pad to ensure the quality of the patch processing.

Temperature is an important parameter for PCB soldering. If it is set incorrectly, it will also cause damage to the circuit patch; also need to pay attention to the transfer soldering operation, place the soldering iron tip between the pad and the pin, and Bring the tin wire close to the tip of the soldering iron and move it to the opposite side when the tin is melted. I hope that through reading the above content, I know that Wuxi SMT patch processing is the correct use of soldering. The above content is just a few precautions for controlling the operation of SMT patch processing. In addition, there is more content that is worthwhile Concerned, in short, we must master the processing points and operate in strict accordance with the specifications.