PCB Hole Plugging Methods
It is common for PCB manufacturers to plug holes in the PCB fabrication process now, especially in the advanced PCB manufacturing and in double-sided plated hole of metal core PCBs. There are some common way used to do hole plugging, they are listed as follows:
The most common one is screen printing, which is popular, cost effective and therefore easily applied, but has great limits. Screen printing can’t guarantee the absence of air in the holes and is unable to work with high aspect ratio holes and blind holes. If through holes can bear some air, then it is suitable just in a small volume.
Another one widely used is electroplating which is really popular in Asia, but it is relatively expensive as it needs a dedicated plating line. Though it is time and energy consuming, it can provide constant and stable results, however, it is only used for blind holes.
Vacuum plugging machines or VPM is a more flexible way, which can be applied for both small runs and mass production, blind holes and through holes. When fill the hole in VPM, the PCB will be put under vacuum, then use different ways depend on manufacturers to fill the paste into holes.