Components Attached to a Micro Via
A micro via is a small through-hole on a PCB that allows for connections between layers in the board. There are several types of microvias that designers can use in their circuits. Some are plated with copper, while others are etched in the substrate material. They are a critical tool for achieving high-density, high-performance PCBs.
Traditionally, through-holes are used to connect pads and traces on a multilayer PCB. However, a microvia can be a simpler solution for connecting components to the board, particularly in high-speed applications where signal radiation and resonance can occur. Microvias are also more durable than through-holes, as they are less likely to crack during soldering.
The process for creating a micro via begins with pre-drilling the layer of copper where the via is located. The hole is then drilled using a laser. This method requires precise calibration in order to produce the desired size and shape of the via. A special tool is required for this type of drilling, and the use of a metal drill bit can cause damage to the microvia walls.
How Are Components Attached to a Micro Via?
After the via is drilled, it is plated with copper in a specialized bath and chemistry. This process can take up to eight hours. It can be completed by using either conformal or pulsed plating to ensure that the body of the microvia is completely filled with copper. Without proper plating, the voids in the microvia can affect the performance of the circuit.
There are many different methods of creating a microvia, including mechanical depth drilling, chemical etching, and laser drilling. The latter is the most reliable and cost-effective option, but it has some limitations. For example, mechanical depth drilling can only create simple hole geometries and is difficult to perform on complex boards. It is also prone to producing burrs and rough surfaces. For this reason, other technologies such as CO2 and UV laser drilling have been developed to meet the demands of the industry.
Another disadvantage of mechanical depth drilling is that it can leave stubs that are not conductive and could cause problems in the assembly process. These stubs can allow for shorting between traces in the same layer, which can lead to signal interference. This can be corrected by using a via filling procedure, but this can add to the manufacturing cost.
A microvia can be a simple way to provide an electrical connection between the outermost and innermost layers of a PCB. It can also be used in combination with blind and buried vias to provide connections between multiple layers of the board. Stacked microvias are a common technique for connecting layers on a double-sided circuit board.
Regardless of which technique is used, the microvia must be properly configured to ensure that it can meet the design requirements of the board. In addition, it must be properly plugged to prevent unwanted connections during the manufacturing process. A poorly plugged via can lead to solder bridges, which are undesirable in high-speed circuits. This is why it is important to choose a fabricator that offers a good quality control (QC) process.
