/What are the process of PCB 01005 precision package?
1. Application of solder paste
As the window of the steel mesh is very small, it is better to use nanometer coating or fine grain nickel steel mesh (FG steel mesh). The thickness of 0.05-0.08 mm is recommended for compatibility with other components.
According to the experience that “at least 5 ball size solder particles can pass through the steel mesh window well at the same time”, choose at least 4 powder solder paste or better 5 powder solder paste.
If the PCB is very thin, such as 0.5-0.65mm, the solder paste printing must be supported by vacuum tooling and the bottom must be clean.
2, the patch
The following factors are the premise to ensure good mounting:
(1) good quality of components (all dimensions must meet the tolerances defined in the document).
(2) good tape quality (all dimensions must meet the tolerance defined in the document).
(3) feeding unit with good precision and repeatability.
(4) a feeder unit with a position reference point.
Once the component is picked up, the graphical recognition system must be of high resolution and precision to accurately calculate and calibrate its position.It is very important to identify and correct the defects such as erecting, side standing and turning.
The patch system must be able to detect if the components are missing (throwing occurs) as the feeder is positioned and the patch is moved.Since the tiny 01005 suction nozzle vacuum induction is very unreliable, the laser induction sensor must be used to detect whether 01005 is lost, as shown in the figure
The z-axis pressure on the components must be controlled, and the too fast speed will cause the solder paste splashing, too high pressure will cause the solder paste crushing and component damage.
The PCB must be well supported and not vibrated during mounting because the vibration will cause the component to shift.
3. Reflow welding
Nitrogen atmosphere is preferred, and the residual itch content is about 45×10 nitrogen 6.Because the solder Korean powder is very fine, very easy to oxidize.In nitrogen atmosphere, the application of wettability improvement can effectively improve the “self-alignment” effect.
The slow preheating slope can prevent stacking and meet the requirement of welding temperature difference.
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