Via-in-pad

In PCB design, vias can be divided into three types: through-hole vias, blind vias, and buried vias, each of which implements different properties and functions and helps the overall best performance of the PCB and even electronics.

For the increasing applications in small electronic products and finer pitch devices, vias in pad become very popular because they are a practical solution responsible for the electrical connection between traces in different layers. And many PCB designers like to use via in pad to increase PCB component density and save board space.

The benefits of via in pad in PCB design

Via in pad(VIP) technology refers to placing vias directly under the component contact pads, especially BGA pads with finer pitch array packages. Via in pad technology has more benefits than blind vias and buried vias as below.

•  More suitable for fine pitch BGA
•  Better performance in thermal management and heat dissipation
•  Help to increase the density of the PCBs and save a considerable quantity PCB spaces
•  Defeat the limits of high-speed PCB designs and reduce inductance in high-frequency PCB board
•  Share a flat surface for SMD component
•  Result in smaller PCB package and further routing

Because of these benefits, via in pad are widely used for small PCBs, especially for high-speed designs, and those who require limited space for BGAs, and excellent performance in heat transfer. Although blind via and buried via have great advantages for increasing density and real estate savings for PCBs, via in pad are still the best choice in terms of thermal management and high-speed design elements.

Besides, via in pad in some designs has many compelling reasons to place the via into the SMT pads of BGA and QFN package components.

•  It can help thermal management
•  It can make routing easier with large-pitch or fine-pitch BGAs
•  It allows real access to the location of the bypass capacitor
•  It can help ground on high-frequency components

Some drawbacks of via in pad technology in PCB fabrication

Via in the pad is a bit of robust technology in PCB manufacturing. The direct reason customers do not design via in pad is that the left open holes will cause some undesirable events during PCB fabrication.

If the vias remain open, the solder will tend to drill down into the vias. The larger the diameter, the more serious the core problem. There may end up not having enough solder to secure the parts or even solder bumps on the bottom of the board, which may interfere with other parts or cause short circuits.

What's more, the price of via in pad is high when compared with the average standard PCB for its complex manufacturing process.

Due to different technology results in various costs and various performance, please contact the engineers in NextPCB for the best solution if you cannot determine which type you need. For the small-pitch components in PCB assembly prototype or PCB mass production, we recommend using capped via in pad to route and make the circuit board routing can be as compact as possible.