As PCBs continue to decrease in size and increase in complexity, manufacturers must keep pace with advanced processes including High Density Interconnect (HDI). At Xekera Systems, one of our specialties, requiring more than fine lines in the foil pattern—it also requires Sequential Build-Up (SBU) and laser-drilled micro-vias.
Laser-drilled micro-vias are smaller in diameter than through-the-board vias, freeing up more space for circuit traces and increasing overall circuit density.
Multilayer technology using SBU involves adding one layer of dielectric and foil pattern at a time, allowing processing of HDI micro-vias before adding another layer.
Filled micro-vias provide stronger connections, better thermal management, and increased overall board reliability compared to unfilled vias.
Multilayer technology using SBU involves the addition of one layer of dielectric and foil pattern at a time, allowing processing of HDI micro-vias before adding another layer.
These layers are added to the substrate in pairs, one layer on each side of the substrate, to balance the stresses to the substrate. For example, 1, 2, 3, etc. layers on each side of the substrate (N), or 1+N+1, 2+N+2, 3+N+3, etc.
A micro-via links only one layer of foil to the next; layers above and below them are available for foil lines, further increasing overall circuit density.
As each layer of SBU is added, a laser drills a hole from the outer layer of foil, through the dielectric that was just laid down, to the next inner layer of foil. This hole is then plated and filled. If there is an additional layer of SBU, the micro-via becomes buried.
At Xekera Systems, we fill the micro-vias with solid metal for stronger connections and to obtain better thermal management, increasing overall board reliability. Filling also allows the micro-vias to be stacked on top of each other to connect three or more layers of foil, further increasing density.
High density I/O components sometimes require Via-In-Pads (VIP) just to connect traces to all solder pads. When VIPs are used, filling the micro-via helps keep the pad smooth, allowing for a better reflow of solder.
Filling also allows the micro-vias to be stacked on top of each other to connect three or more layers of foil, further increasing density and design flexibility.
Contact Xekera Systems for more information about HDI technology and laser-drilled micro-vias. Our team of experts is ready to help you design and manufacture advanced PCBs for your next project.
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