Blind Via and Buried Via

Blind Via and Buried Via

Vias, that is, copper plated holes, play a key role in the interconnection between layers in a printed circuit board. Generally speaking, vias in PCBs can be classified into through-hole via, blind via and buried via. Blind vias and buried vias are widely applied in SMT (Surface Mount Technology) just to compensate for disadvantages of through-hole vias, they can be further classified into plugged via (copper or solder mask), plated via, staggered via etc. based on different processing measures.

through-hole via, blind via and buried via | PCBCart

Blind via connect one external layer and one or more inner layers in printed circuit board, responsible for interconnection between top layer and inner layers or bottom layer and inner layers.

Buried via connect only inner layers inside printed circuit board so that they are invisible just from the outer appearance of a PCB since they are internally "buried".

As blind/buried vias contribute to the density improvement of boards without the need to increase number of layers or board size, they are usually applied in HDI PCBs. Put in another way, they can be picked up when you suffer from tight requirement of limited space and through-hole hassles.

Stacked Via and Microvia

To be compatible with demands of miniaturization and high signal transmission speed of modern electronic products, PCB real estate reduction and density improvement have been regarded as PCB designers' top considerations in circuit design. As is discussed above, through-hole vias and blind/buried vias play an essential role in connectivity implementation between layers in multilayer PCBs. When it comes to blind vias whose aspect ratio is over 1:1 or drilling needs covering multiple layers, stacked vias can be relied on to ensure better internal connection.

Stacked vias are actually lamination of blind vias, that is, a couple of blind vias on inner layers of a circuit board are built together around the same center through layers. On the whole, stacked vias are either blind vias or buried vias. By the way, another type of laminating vias, staggered vias, however, don't surround the same center although they are also manufactured through lamination.

Stacked Via and Microvia | PCBCart

Stacked vias are usually applied in HDI PCBs for their following merits:
• Routing capacity improvement
• Less parasitic capacitance
• Density increasing
• Space saving
• More flexibility in inner connection

Nevertheless, the key disadvantage of stacked vias lies in higher cost compared to pure through-hole vias and blind/buried vias. Thus, its best to consult with PCB manufacturer prior to making orders on optimal balance between cost and functions.

PCB designers would expect via diameter be as small as possible to enable more routing space on board. Furthermore, the smaller via diameter is, the lower parasitic capacitance will be, which is more suitable for high-speed circuits. Accordingly, microvias are in great need. It has to be admitted that vias can never be infinitely small since via production is closely related with performance of drilling and plating. The smaller via diameter is, the longer time drilling needs and the more off-centered via moves.

Because agreed definition of microvias hasn't been achieved by the industry, PCB manufacturers hold different views on them. Moreover, due to distinctive manufacturing capabilities between PCB fabricators, each manufacturer possibly holds different views on microvias. For example, PCBCart considers vias whose diameter is less than 0.1mm as microvias. Accordingly, it's best to consult with them on their manufacturing capabilities concerning minimum diameter before submitting orders.

PCBCart Prints PCBs with Blind/Buried Vias and Stacked Vias/Mircrovias

Due to over 10 years' experience in this industry, PCBCart specializes in manufacturing PCBs with blind vias and buried vias. We're capable of providing both mechanically-drilled and laser-drilled solutions, and we have the capabilities to make via tented/covered with resin, via plugged/filled with resin and many other custom required vias. The following table shows design parameters on blind vias and buried vias manufactured by PCBCart:

Via pad, Via Diameter, Annular ring on Printed Circuit Board | PCBCart

Via Type Via Diameter
Via Diameter
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

Based on your project's demand that should depicted in detail through generating NC drill file, you can choose corresponding drill diameters in the items while getting quotations. Use our PCB price calculator to quote for your custom PCBs with blind vias or buried vias within seconds. Click the following button to enter calculation page, input circuit spec, click Additional Options and check Buried/Blind Vias option, then select Times of Buried/Blind Via, price will be automatically showed up in the right column.

Quote for PCBs with Blind/Buried vias

Helpful Resources
Pre-order File Checklist
PCB Design Tips to Better Take Advantage of PCBCart's Capabilities And Save Cost
Step-by-step Instruction On Getting Bare Board PCB Price Within Seconds
How to Design Blind/Buried Vias in High-Speed Digital Circuits
3 Important Elements You Don't Know about Buried and Blind Via in HDI Flex-rigid PCBs
Failure Analysis on Blind Via for Empty Cave in PCB Filling Copper Plating

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