Several methods of PCB blind hole production
Blind via in PCB is a hole connecting different layers, specifically those holes that only penetrate one or several layers in a multi-layer circuit board, but not completely penetrate all layers. In high-density PCB design, blind vias provide effective space utilization and reduce the required wiring area. Reducing the path length can also reduce signal delay, thereby improving signal integrity. By using blind vias, the number of layers of PCB can be reduced, thereby reducing manufacturing costs. The design of blind vias can also make the arrangement of signal and power lines more flexible and achieve more complex circuit layouts. The following are several common methods for making PCB blind vias:
Mechanical drilling:
This is one of the most common methods for making PCB blind vias. First, drill the hole position on the PCB board according to the design requirements, and then control the depth of the drill bit to form a blind hole. This method is suitable for thicker PCB boards and larger apertures.
After mechanical drilling, the hole wall is usually deburred and cleaned to ensure the quality of the blind hole.
Laser drilling:
Laser drilling technology uses the high energy and high precision characteristics of the laser beam to directly drill blind holes on the PCB board. This method is suitable for blind hole production of high-density, small-aperture and multi-layer PCB boards.
The advantages of laser drilling are high precision and high speed, but the equipment cost is relatively high.
Plasma drilling:
Plasma drilling is a method of drilling holes using the high temperature and high energy characteristics of plasma. It generates plasma by ionizing gas, and then uses the energy of plasma to process the PCB board.
This method is suitable for making small-aperture and high-precision blind holes, and can process multiple holes on multi-layer PCB boards at the same time.
Chemical etching:
Chemical etching is to coat a layer of photosensitive material on the PCB board, and then use photolithography technology to transfer the blind hole pattern to the photosensitive material. Next, the PCB board is immersed in an etching solution, and the part not covered by the photosensitive material is removed by chemical reaction to form a blind hole.
Chemical etching is suitable for making large-volume, small-aperture blind holes, but the processing time is long, and the requirements for etching solution and photosensitive materials are high.
Micro punching:
Micro punching is a method of punching holes on a PCB board using a micro punch. This method is suitable for making small-diameter and high-precision blind holes, and can process multiple holes on multi-layer PCB boards at the same time.
The advantages of micro punching are high precision and fast speed, but the equipment cost is high, and there are certain requirements for the material thickness and hardness of the PCB board.
Electroplating filling:
In some cases, electroplating filling may be required after the blind hole is made to enhance its conductivity and connectivity. Electroplating filling usually uses copper or other conductive materials to fill the blind hole.
Electroplating filling can be performed in the subsequent process after the blind hole is made, or it can be combined with other blind hole making methods.
It should be noted that different PCB blind hole making methods have their own advantages and disadvantages. Choosing a suitable method requires considering factors such as the design requirements, material properties, production costs and delivery time of the PCB board. At the same time, quality inspection and testing are required after the blind hole is made to ensure that it meets the design requirements and usage requirements.
