What is a Via?

Vias are the copper-plated holes in the PCB that allows the layers to connect. The standard via is called a through-hole via, but there are several disadvantages to using through-hole vias in Surface Mount Technology (SMT). For this reason, we often use a blind via or buried via instead. A blind or buried via can be processed in a wide range of different measures, including plugged copper mask via, a plugged solder mask via, plated via or staggered via.

• What is Blind Via?

In a blind via, the via connects the external layer to one or more inner layers of the PCB and is responsible for the interconnection between that top layer and the inner layers.

• What is Buried Via?

In a buried via, only the inner layers of the board are connected by the via. It is “buried” inside the board and not visible from the outside.

Blind and buried vias are particularly advantageous in HDI board because they optimize the density of the boards without increasing board size or the number of board layers you require.

• What is Stacked Via and Microvia?

A stacked via is a way to further improve size and density considerations when manufacturing PCBs — factors that are extremely important with today’s miniaturization and high-signal transmission speed requirements in many applications.

If you have blind vias with an aspect ratio greater than 1:1, or your drilling needs cover multiple layers, a stacked via can be the best way to get a reliable internal connection.

Stacked vias are laminated blind or buried vias, multiple vias inside a circuit board built together around the same center. Staggered vias are laminated vias that are not around the same center. The advantages of stacked vias include not only saving space and increasing density, but greater flexibility concerning the inner connections, better routing capacity and less parasitic capacitance. The downside of stacked vias is that they come with a higher cost than standard through-hole vias or blind/buried vias.

A microvia is merely a very small via. As you can imagine, microvias are very desirable to PCB designers — the smaller the diameter, the more routing space you have on the board and the lower the parasitic capacitance, which is essential for high-speed circuits. However, very small vias also require more drilling time and more off-center via moves. KKPCB defines microvias as vias with diameters of less than 0.1mm.

Contact PCBCart for PCBs With Blind/Buried Vias and Stacked Vias/Microvias

KKPCB has years of experience manufacturing PCB using blind and buried vias. No matter what it takes, we can make exactly the blind or buried via PCB you need for you. The following table shows design parameters on blind vias and buried vias manufactured by KKPCB:

• Via Type Via Diameter

Via Type	Via Diameter (max.)	Via Diameter (min.)	Via Pad	Annular Ring	Aspect Ratio
Blind via (mechanical)	0.4mm	150μm	450μm	127μm	1:1
Blind via (laser)	0.1mm	100μm	254μm	150μm	1:1
Buried via (mechanical)	0.4mm	100μm	300μm	150μm	1:10
Buried via (laser)	0.4mm	100μm	225μm	150μm	1:12

KKPCB conducts research on special processing technologies such as ordinary double-sided boards, thick copper circuit boards, high-frequency circuit boards, HDI circuit boards, rigid-flexible circuit boards, FPC flexible boards, buried blind hole circuit boards, and IC carrier boards. Provides PCB design, PCB layout, PCB prototyping and PCB assembly services.