PCB vias are the holes in printed circuit boards for electrical connection between different PCB layers, PTH component mounting, or connection with external components (screws, connectors, etc). In this post, you will get an insight into PCB vias and their different types of details.
#1. Through-Hole Vias
The most common and easiest PCB vias are through-hole vias. Though-hole vias are drilled from the PCB's upper layer to the bottom layer. When you take a PCB and look at it facing the light, the holes where light passes through are the through-hole vias.
Though-holes vias are mainly PTH (plating through-hole) vias, and some are NPTH (non-plating through-hole) vias. PTH vias are used for PTH assembly or electrical connection between different PCB layers, while NPTH is used for mechanical connection with screws or connectors to fix the PCB.
How do you distinguish PTH and NPTH vias? It's easy. Just look at the hole wall to see whether it is electroplated or not.
Though-hole vias cost the lowest but take much PCB space. If the circuit connection is not from the upper layer to the bottom layer, you can turn to other PCB via types to save space.
#2. Blind Vias
Blind vias are drilled and electroplated from the PCB's upper or bottom layer to an internal layer. When you look at the blind via on the PCB facing the light, you cannot see the other side through the hole.
Blind vias can be laser-drilled or mechanical drilled. For blind vias, the drilling depth has to be accurate. Blind vias can be directly drilled on the PCB, but this is difficult. And it makes electroplating also difficult. More commonly, advanced PCB manufacturers drill holes on the required circuit board layers and then pile up the layers to create blind vias and electroplate them.
#3. Buried Vias
Buried vias are drilled and electroplated between the PCB's inner layers, and you can't see them from the externality. Buried vias are used to connect the circuit between two or more inner layers.
Unlike the blind via, if a buried via connects 3+ inner layers, it can't be directly drilled on the PCB. The PCB manufacturer can only drill holes on the required PCB layers and then pile them up to electroplate the hole wall.
When creating blind vias or buried vias by drilling and compiling different PCB layers, there can be two cases: holes-to-connect overlap or not. And this difference leads to two PCB via types - overlapping vias and staggered vias.
# 4: Stacked vias
Stacked vias can be blind vias or buried vias to connect circuits between different PCB layers across 3+ circuit layers. For example, via 3-6 in the below image is a stacked via as well as a buried via.
Via 1-3 in the below is a stacked via as well as a blind via.
Compared with staggered vias, designing stacked vias is easier but its manufacturing cost is higher. This is because the holes on different layers have to be drilled at the same place, and when compiling the layers, the holes together form a complete stacked via with a flat hole wall. And it requires extreme precision for the PCB manufacturer.
But no worry. You can ask PCBONLINE, a leading HDI PCB manufacturer, to manufacture PCBs with stacked vias easily.
When the PCB layers pile up, the PCB manufacturer electroplates the stacked hole wall and then deals with other layers.
#5. Staggered Vias
When vias of different PCB layers are connected but not overlapping, they form a staggered via. For example, in the below, via 1-2 and via 2-3 form a staggered via.
Staggered vias are more complex to design, but their manufacturing cost is lower than stacked vias. This is because vias of different PCB layers do not overlap when compiling the layers, and much less precision is required than stacked vias.
#6. Skip Vias
A skip via is a PCB via that penetrates multiple circuit layers but makes no electrical connection with a specific layer or layers. It can be an overlapping via, a blind via, or a buried via. For example, the via 3-6 as below is also a skip via that goes across four circuit layers and connects two circuit layers.
Microvias are blind/buried via structures with a maximum diameter of 0.15mm, a maximum aspect ratio of 1:1, maximum depth of 0.25mm. It penetrates across only two PCB circuit layers.
A microvia can be drilled in a PCB external layer to be a blind via, or drilled in a PCB internal later to be a buried via. When microvias on different PCB layers overlap, they form overlapping vias, when connected by wires and not overlapping, staggered vias.
#8: Vias in Pad
The least common type of PCB via is the via-in-pad. Only big PCB pads such as the pads of MOSFET and BGA can be drilled with holes, and the hols on big PCB pads are vias-in-pad, which are used for thermal dissipation of the components.
Whether or not to design the via-in-pad? It all depends on the actual situation, and you need to know its pros and cons.
- Pros: a via-in-pad provides convenience for routing and avoids parasitic inductance of vias.
- Cons: during reflow soldering, solder paste may flow through the via, and it causes poor soldering on the PCB pad.
However, the one-stop PCB manufacturer PCBONLINE has rich experience in SMT assembly for vias-in-pad. If your design vias-in-pad is on PCB, you can ask PCBONLINE to manufacture and assemble your PCBs at one stop.
PCBONLINE: One-Stop PCB Manufacturer Easily Deal With Any PCB Via Types
If you design PCBs with the above PCB vias, don't worry about PCB manufacturing and assembly. PCBONLINE, a one-stop advanced PCB source factory manufacturer, manufactures and assembles PCBs with any PCB vias with the highest quality. No matter you need HDI PCBs, high-frequency PCBs, ceramic PCBs, MCPCBs, FR4 PCBs of any Tg, or flexible PCBs, you can avail of one-stop PCB fabrication and value-added services from PCBONLINE.
Here are the reasons to choose PCBONLINE to deal with PCBs with PCB vias:
- PCBONLINE can drill any PCB vias easily such as blind/buried/staggered/stacked/skip/micro vias.
- PCBONLINE manufactures and assembles PCBs with any PCB vias to IPC-A-610 Class 3 standards.
- PCBONLINE provides HDI PCBs, high-frequency PCBs, ceramic PCBs, and so on with any PCB via types.
- Solution experts provide one-on-one engineering support and DFX to your PCB projects.
- Besides various PCB vias, PCBONLINE also deals with PCB pads in different shapes easily.
PCBONLINE's target clients are senior engineers, electrical solutions companies, research institutes, and business makers, from medical, aerospace, defense, automotive, industrial, communication, and consumer electronics. If you are seeking a reliable advanced PCB manufacturer, PCBONLINE is one of the best options.
This article lists and introduces all 8 types of PCB vias. You can find that a PCB via can be a blind/buried via, a stacked /staggered via, and a skip via simultaneously. PCB via types are just the names, and what matters is how you use them for circuit connection between different PCB layers. When you design PCBs with various vias, do not worry about PCB manufacturing and assembly. PCBONLINE is always a reliable solution expert and one-stop manufacturer.
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