guidelines related to PCB via fill
PCB via fill is a process where the plated hole is filled with either conductive or non-conductive material to enhance reliability by decreasing the probability of air or liquid getting trapped. It also allows for the implementation of a Via-In-Pad or active pad process, which can help shorten signal paths on a PCB and increase performance. Via fill is important because it prevents impurities, strengthens pad attachment, reduces solder wicking and silkscreen printing issues, improves mechanical strength, and helps with thermal and current capacity. It is also an essential part of the manufacturing process, and there are specific requirements that must be followed to ensure success.
Conductive pcb via fill is the most common, and it uses copper or silver epoxy to provide superior conductivity and current capacity. It’s a great choice for high-speed applications that require high levels of current and heat transfer, and it provides good signal transmission through the vias. In addition, conductive via fill is a good choice for dissipating heat underneath IC components.
Another option is non-conductive via plugging. This uses an epoxy resin to create a seal that prevents solder from flowing into the holes during the assembly process and protects them from corrosion and other damage. In addition, a plugged via can prevent unnecessary solder joints.
Are there any industry standards or guidelines related to PCB via fill?
A third technique, which is more cost-effective but less reliable, is capped vias. In this case, the unused vias are closed or shut during the fabrication process to avoid the additional steps of filling, planarization, and plating over that would occur with a conductive via fill. This is an effective way to save money and time on a low-volume production run, but it’s important to consider the CTE differences between the material used for filling and the material used to cap the vias.
When choosing a supplier, it’s important to work with one who has the necessary equipment and technology to offer these services. It’s also a good idea to specify which via cover type you need when ordering your board, so the supplier can plan accordingly.
In addition to making sure the board is devoid of contaminants, the fabricator must follow strict IPC standards when determining via size, drilling method, and other factors that affect how well a via can be filled. Once all this is done, it’s time to start the actual process of creating the vias. This is done by using a laser to drill through pairs of layers, or through a sequential layer build method. The drilled holes are then filled and sealed with epoxy before the next pair of layers is stacked on top. The process can be time-consuming and expensive, but it’s essential to ensuring quality and reliability on a complex printed circuit board.
Choose an appropriate via fill material based on the intended application and performance requirements. Conductive materials such as copper fill are commonly used for thermal management, while non-conductive materials like epoxy fill are preferred for reducing EMI and improving mechanical stability.