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What is a PCB Via Stub?

Vias

Editorial Team - PCB Directory

Mar 13, 2022

A Via is a drilled conductive copper hole in a multilayer PCB used to make electrical connections between layers. A via stub is the unused part of a via. It does not connect any layers and does not have any any useful function (Figure 1). The unused via or the stub of a multilayer PCBs is the cause for impedance discontinuity in the line.Figure 1: via stubThe impedance discontinuity can affect the...read more

What is PCB Interconnect Stress Testing (IST)?

Editorial Team - PCB Directory

Jun 14, 2020

PCB Interconnect Stress Testing (IST) is a process to identify failures in vias and multilayer interconnects by consistently monitoring resistance variations. This testing is performed on a PCB test coupon, where it undergoes several thermal cycles. These thermal cycles are created by applying current to a specific test coupon. IST is a way to check the reliability of the PCB board. This process a...read more

What is Via Plugging?

Vias

Editorial Team - PCB Directory

Aug 22, 2021

Via plugging is a process in which vias are completely filled with resin or closed with a solder mask. This technique is different from via tenting where resin/solder mask doesn’t fill the via hole but just provides a covering.Via plugging is done as a preventive measure to secure the vias from the unwanted flow of solder material during the assembly/soldering process. During the soldering p...read more

What is a Through Hole Via?

Vias

Editorial Team - PCB Directory

Aug 22, 2021

A Through-Hole Via is the most common type of via used in PCBs. They are formed by drilling a hole through the Printed Circuit Board from top to bottom connecting all the layers of a Multi-Layer PCB. Through hole Vias can be constructed by using a drill or laser. These are easy to construct and are the most cost-effective type of vias.Through-Hole Vias do have some disadvantages - because they con...read more

What are Tented Vias?

Vias

Editorial Team - PCB Directory

Aug 22, 2021

Tenting or capping in PCB means covering the annular ring and via hole with solder mask. Tented Vias are those that are completely covered with soldermask. Via tenting is performed to reduce the number of exposed conductive pads on a PCB which in turn mitigates the probability of physical damage like corrosion and shorts happening due to solder bridging.Via Tenting has several advantages for Print...read more

What is a Microvia?

Vias

Editorial Team - PCB Directory

Jan 21, 2022

A Microvia is basically a very small via. Most PCBs now days are multi-layer boards. Vias are used to make connections between each layer of the printed circuit board. Microvias, as the name suggests have a smaller diameter and thus take up less board real estate and leave more space for routing. They also have a lower parasitic capacitance which is important for high-speed circuits. However, the ...read more

What is Via Filling?

Vias

Editorial Team - PCB Directory

May 20, 2020

A Via is used to connect multiple layers of a PCB so that it can perform its intended functions. Via Filling is a PCB manufacturing technique in which the via hole is filled with epoxy. This process partially or completely closes the via hole using a conductive or non-conductive epoxy filling material. Filling Via Holes results in more reliable surface mounts, provide better assembly yields and im...read more

What is a Via?

Editorial Team - PCB Directory

Aug 22, 2021

A Via is used to make an electrical connection between the layers of a Multi-Layer PCB. Connecting multiple layers of a board makes it possible to reduce the size of the PCB, as layers can be stacked. A via is constructed by placing copper pads on each layer of the PCB and drilling a hole through them. The hole is made conductive through electroplating or by placing copper cylinders directly in th...read more

What are Stacked Vias?

Vias

A Stacked Via is a type ofviastructurethat consists of two or more vias placed directly on top of each other, traversing multiple layers of the PCB.They are used inmulti-layer printed circuit boards (PCBs), and especially inhigh-density interconnect (HDI)designs.Each via in the stack connects to at least one inner layer of the board. The primary purpose of stacked vias is to provide a continuous e...read more

What are Staggered Vias?

Vias

A Staggered Via is a type ofviastructurethat consists of multiple (two or more) vias in an arrangement such that they are never in direct contact with each other as their drill axes are separate which offsets their position on adjacent layers. As staggered vias have a different position in each layer they form a zigzag pattern when the PCB is viewed from the top or bottom of it. They are most ofte...read more

What is a Blind Via?

Vias

Editorial Team - PCB Directory

May 16, 2023

Blind Vias are an essential component of modern printed circuit board (PCB) design, specifically multi-layered PCBs. They are small holes that are drilled into the board to connect the different layers of a PCB. Blind vias are called so because they only go partway through the board, stopping at a specific layer rather than running through the entire board. This allows for the creation of more com...read more

What is a Buried Via?

Vias

Editorial Team - PCB Directory

May 16, 2023

Buried Vias are an essential component of modern printed circuit board (PCB) design, specifically multi-layered PCBs. They are small holes that are drilled into the board to connect the different layers of a PCB. Buried vias differ from blind and through-hole vias because they are located between two inner layers of the PCB and do not penetrate through the surface of the board. This allows for the...read more

What is Backdrilling in PCB Fabrication?

Editorial Team - PCB Directory

Aug 17, 2020

Back drilling or Controlled depth drilling is a process used to remove the unwanted portion of a PCB Via Stub. Plated Through Hole (PTH) Vias are used to connect two or more layers of a Printed Circuit Board to each other. However often, a via does not need to run the entire thickness of the board to connect each layer. For example, if we have a 10 layer PCB and need to connect layer 1 to layer 3 ...read more

What is Via in Pad?

Vias

Editorial Team - PCB Directory

May 20, 2020

‘Via in Pad’ is when the via is placed directly on the pad of a surface mount component. Once this is done, the via is filled with conductive or non-conductive epoxy, followed by capping and electrochemical plating to make it virtually invisible. Such type of arrangement results in buried via within the PCB surface that can be completely soldered as standard SMT lands.The Via in Pad ca...read more

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