Advanced PCB technologies
As the PCB market shifts from PC to high-frequency communications, smart devices, and automotive electronics fields, the PCB manufacturing and assembly industry are undergoing a series of changes. Now that the products are becoming smaller, more functions are required, if you have a deeper understanding of PCB manufacturing, you may understand the difficulties, how to do with them? Fortunately, come up with lots of more advanced PCB processes, PS sorts out three frequently asked ones here.
To overcome the limit in creating fine circuitry of the traditional etching method, the semi-additive process was come up with. The semi-additive process refers to double plating. The main process is first plating a layer of copper which is very thin (<0.1mil) on the substrate, then plating the traces and PTHs again after PCB imaging. So that the circuit will not be affected in etching, we can create finer traces.
- Good for the PTHs that have no solder lugs or have solder lugs in the same sizes,
- Can support high-aspect ratio, good for thick copper holes and thick copper boards.
- Not good for NPTHs in big sizes,
- More expensive cost.
The build-up process, commonly used for making HDI advanced PCBs. The traditional way of making a multilayer PCB is to make the inner and outer layers separately and then press together. And for the build-up process, we create inner layers first then add more layers on both sides. In which blind/buried vias are usually drilled by laser to shorten the production process. In addition, the build-up process can produce finer circuits, trace/spacing are able to reach 2/2mil. But it required more advanced equipment for plating micro-vias, so it is still difficult and cost more.
We might meet the issues that there remain air bubbles in the laser drilling blind/buried vias, which affects advanced PCBs’ reliability after thermal shock. The conventional methods are to fill the blind/buried vias with a resin or special resist. However, these methods are difficult and the efficiency is low. In order to improve the processing, via filling is brought in, to fill blind/buried vias by electroplating, which greatly increases the reliability. To achieve good filling while the required copper weight, more advanced equipment, and special plating solutions are needed, which still mean difficulty and high-cost.