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World Class Blind and Buried Vias PCB Manufacturer in China

Blind and buried vias are used to connect between layers of a PCB where space is at a premium. A Blind Via connects an outer layer to one or more inner layers but does not go through the entire board. A Buried Via connects two or more inner layers but does not go through to an outer layer.

Via hole is one of the important components of multilayer PCB, and the cost of drilling usually accounts for 30% to 40% of the cost of PCB manufacturing. Simply saying, every hole on the PCB can be called a via. From the point of view of function, vias can be divided into two categories: one is used for electrical connection between layers; the other is used for fixing or positioning devices. In terms of process, these vias are generally divided into three categories, namely blind vias, buried vias and through vias. Blind vias are located on the top and bottom surfaces of the printed circuit board and have a certain depth. They are used to connect the surface line and the underlying inner line. The depth of the hole usually does not exceed a certain ratio (aperture). Buried via refers to the connection hole located in the inner layer of the printed circuit board, which does not extend to the surface of the circuit board. The above two types of holes are located in the inner layer of the circuit board, and are completed by a through-hole forming process before lamination, and several inner layers may be overlapped during the formation of the via. The third type is called a through hole, which penetrates the entire circuit board and can be used for internal interconnection or as a component mounting positioning hole.

Frequently Asked Questions (FAQ) About Our Blind and Buried Vias PCB Boards Process and Capabilities

Here you will find many quick questions and answers about Blind and Buried Vias PCBs,don’t hesitate to contact us,our email is sales@pcbmay.com.

A Via hole in a PCB consists of two pads in corresponding positions on different layers of the board, that are electrically connected by a hole through the board. The hole is made conductive by electroplating.Barrel — conductive tube filling the drilled hole.

Vias are used to electrically and thermally join traces, pads, and polygons on different layers of a PCB. Vias are copper cylinders that are placed or formed in holes that have been drilled in a PCB.

Blind and buried vias are used to connect between layers of a PCB where space is at a premium. A Blind Via connects an outer layer to one or more inner layers but does not go through the entire board. A Buried Via connects two or more inner layers but does not go through to an outer layer.

Tenting a via means you create a tent-like shape over the hole to cover the via. The purpose of tenting is to limit the number of exposed conductive pads on the PCB. When a via is tented, the manufacturer used a solder mask to enclose the opening.

A stacked via consists of multiple vias layered directly on top of each other. Each via is first drilled and then metalized, leaving a small annular ring at the top and bottom to ensure electrical connection.

The PCB aspect ratio is simply defined as the board thickness to the diameter of the drilled via. This is an important ratio due to its effect on the plating that is within the vias (as also affected by the annular rings). Say you have a board with a thickness of 0.2” and a via drill diameter of 0.02”.

With increasing demand of miniaturization and high integration of electronic products,more and more PCB layout designs adopt blind and buried vias technology to improve circuit density of PCB boards.PCBs with blind and/or buried vias have more space to wiring than standard PCBs.And blind and buried vias are widely used in multilayer printed circuit boards manufacturing.

What is Via Hole

A via hole in a PCB is a copper through-plated hole, which consists of 2 pads in corresponding positions on different layers of the circuit board, that are electrically connected by a hole through the board. The hole is made conductive by electroplating.Barrel:conductive tube filling the drilled hole
Pad:connects each end of the barrel to the component,plane or trace.
Anti-pad:clearance hole between barrel and no-connect metal layer.

Blind&Buried Via 1

What is Blind Via

Connects an outer layer to one or more inner layers but does not go through the entire board,and they are visible from the one outer layer but not visible from the other outer layer.

What is Buried Via

Connects two or more inner layers but does not go through to an outer layer, and they are not visible from any one of the outer layers.

Blind&Buried Via PCB 2

Blind and Buried Vias Manufacturing Capabilities

We use combination of depth-controlled laser drilling and mechanical NC drilling to manufacture the blind and/or buried vias.The blind and buried vias manufacturing capabilities for standard PCBs and HDI PCBs as following.

Blind&Buried Via PCB 3

Via TypeVia Diameter
(max.)
Via Diameter
(max.)
Via PadAnnular RingAspect Ratio
Blind via (mechanical)0.4mm150μm450μm127μm1:01
Blind via (laser)0.1mm100μm254μm150μm1:01
Buried via (mechanical)0.4mm100μm300μm150μm1:10
Buried via (laser)0.4mm100μm225μm150μm1:12

HDI PCB Stackup Types

There are two prevalent methods of dividing HDI stickups into different types.One is the IPC classification,which divides HDI Stackups into Types I to VI.Out of these six types,most commonly used are type I,type II and Type III.

The other type of HDI stackup is M+N+M.Where M stands for the number of HDI layers and N represents the number of layers in the core. For example,a 1+6+1 stackup would mean that the central core has six layers while one HDI layer on either side.

Blind&Buried Via PCB 4

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