Laser Drill Micro Vias

HDI and Micro-Vias

At PCB Runner, we as fabricators must keep abreast of the increasing complexity of PCBs as they continue to decrease in size. Moreover, designers revise and improvise old processes as they add new ones. This includes the necessity for High Density Interconnect or HDI PCBs. Therefore, we always strive to stay ahead of whatever new technology is appearing on the market.

HDI is one of our specialties, and PCB Runner understands that there is more to HDI technology than just fine lines in the copper layers. That is why we offer our customers Sequential Build-up and laser-drilled micro-vias.

Sequential Build-Up

PCB Runner uses Sequential Build-Up in Multilayer technology. This involves adding a combination of a dielectric layer and a foil pattern at a time to the stack. This process offers the advantage of processing HDI micro-vias in the layer, before another layer addition. As we add these layers to the substrate in pairs, with one layer on each side of the substrate, the effect is a balance of stress on the substrate. For instance, if we must add layers 1, 2, 3 on each side of the substrate N, we add them as 1+N+1, then 2+N+2, and 3+N+3, and so on.

Laser-Drilled Micro-Vias

PCB Runner uses laser-drilled micro-vias as this technology reduces the space taken up by all the through-hole vias. Laser-drilled micro-vias are much smaller in diameter compared to regular vias, which means more space is available for routing circuit traces.

By its construction and technology, the micro-vias and link only one layer of foil to its immediately neighboring foil. As the foils above and below the joined foils are available for routing, the technique increases the overall circuit density.

While adding each layer of the SBU, we laser-drill a hole from the outermost layer of foil, penetrating the dielectric we just laid, to the next inner layer of foil. Then we plate and fill up this layer, before adding the next layer of SBU. This process makes the micro-via a buried micro-via. Unlike other fabricators, PCB Runner always fills up the micro-vias using metal. This makes the connection stronger and more reliable. It also offers better heat transfer, resulting in better thermal management, thereby improving the board reliability even further.

laser-drilled micro-vias


Although in regular boards using vias within pads can lead to connections becoming dry during reflow soldering, via-in-pads or VIP are unavoidable in high density boards. To avoid problems with VIPs, PCB Runner fills up the micro-vias and plates them to keep the pad smooth, thereby allowing for a proper reflow.

Filling up the laser-drilled micro-vias also has another advantage, allowing them to stack up atop one another, allowing electrical connection between three or more layers of foil. Stacking micro-vias helps to increase the design density even further.

Whatever be your requirement of high-density or HDI boards, you can get more information at PCB Runner. Contact us now on our website, email us, or talk to us over phone today.