Microvias Be Filled With Conductive Material
The use of microvias in a printed circuit board (PCB) allows for more efficient distribution of localized heat generated by power components. This improved thermal management helps ensure the structural integrity of the PCB, and can reduce the risk of hotspots that can damage or destroy high-power electronics. However, the small size of these holes makes it difficult to ensure proper filling without voids and other defects that can affect reliability. To avoid these issues, it’s crucial to select the right fabrication process and materials for your design.
In addition to the quality of the copper filling, the substrate material used to create a microvia also has a significant impact on its performance and reliability. These considerations include both the electrical conductivity and mechanical properties of the material. The material must be compatible with the drilling, metallization, and surface finish processes used to produce the microvias, and provide the necessary strength and stability.
A common type of ICD affecting vias is debris-based, caused by a particle that gets embedded in the inner-layer copper during the hole-drilling process. Fortunately, lasers used to drill microvia holes generate much less debris than other hole-drilling techniques, reducing the risk of this problem. However, it’s still important to carefully check for debris, residue, drill smear, fiberglass, inorganic fillers and other foreign material before filling the microvias with copper.
Can Microvias Be Filled With Conductive Material?
The other primary issue affecting the performance of microvias is voiding. A void can cause stress concentration near the center of the via barrel, resulting in an increase in failure rate. Voids can also lead to corrosion and electrical instability. The impact of a void on microvia reliability depends on its size, shape and location. Small spherical voids have a minor effect on via reliability, while extreme voiding conditions can significantly decrease the life of a microvia.
Despite the challenges associated with microvias, they continue to be widely used in high-performance electronic devices. Their ability to minimize electromagnetic interference (EMI) and improve signal transmission speed make them an attractive option for many applications, particularly those that require higher-density interconnects.
To maximize the benefits of microvias, designers should incorporate them into their designs as early as possible. This will help reduce manual routing time and allow for more complex layouts to be constructed. As such, it’s essential to define the locations and dimensions of the vias in the layers of the PCB stackup using an advanced design tool, such as Epec’s Stackup Editor.
Once the stackup is defined, it’s advisable to send it to your fabricator for review and comment prior to ordering the boards. The fabricator’s feedback can help you determine which fabrication process is best suited for your design, and which materials will give you the best results. This can help you build a PCB that meets your requirements, while minimizing manufacturing issues and maximizing the efficiency of the assembly process.