Discussion on machining technology of plug hole

- Aug 18, 2018-

In the era of HDI high-density connection technology, line width and line spacing will inevitably become smaller and denser, which leads to the emergence of different types of PCB structures, such as Via on Pad, Stack Via, etc. Under this premise, embedded holes in the inner layer are usually required to be fully filled and ground to increase the wiring area of the outer layer.The market demand not only tests the PCB industry's manufacturing capacity, but also forces the original material supplier to develop hi-tg, Low CTE, Low water absorption, solvent-free, Low shrinkage, easy to grind and other characteristics of the plug ink to meet the industry demand.The main processes of the plug section are drilling, electroplating, roughening of the hole wall (processing before the plug hole), punching, baking, grinding, etc.The process of making resin plug hole is introduced in detail.

At the same time, all Via holes should be filled with ink or resin due to the packaging needs of the outer circuit, so as to prevent any other functional hazard caused by tin hiding in the holes.

The current plug hole method and ability

The current plug hole method generally adopts the following technologies:

1. Resin filling (mostly used for inner plug hole or HDI/BGA packaging plate)

2. Printing surface ink after hole drying

3. Use blank network with plug and tape printing

4. After HAL

Three plug hole process and analysis of advantages and disadvantages

Screen printing plug hole is widely used in the industry, because the main equipment required by the printing machine is generally owned by various manufacturers;And necessary tools such as: printing plate, registration Pin under the screen, scraper, and so on also is almost everywhere in the regular material, its process is not a very difficult operation, with a single stroke of the scraper printing in consistent with the inner plug hole aperture location on the screen, by printing pressure will ink into aperture, at the same time to make the ink smoothly into hole inner lining plug hole plate below, need to prepare a plate under for plug hole aperture breathable, make the hole in the process of plug hole smooth discharge of the air inside, and the effect of 100% full.Even if to conform to the requirements of the plug hole quality, the key lies in optimizing the parameters of the operations, which contains the screen mesh, tension, scraper hardness, Angle, speed, etc all can affect the quality of plug hole, and different plug hole aperture aspect ratio have different parameters, has the experience of workers required to get the best operation conditions.