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HDI PCB / Blind&Buried Via Hole PCB / BVH PCB

SPEEDAPCB has been focusing on the production of various PTH (plated through hole PCB), buried via hole PCB and blind via hole PCB, and HDI PCB prototype.

When it comes to blind and buried hole circuit boards, everyone thinks of HDI boards. Generally, there are more blind and buried hole circuit boards used in mobile phones or navigation instruments. Such PCB boards require high technical content and accurate accuracy. Of course, the price is compared with other It is also high for multilayer circuit boards.

HDI high density interconnect pcb : 1 + n + 1, 1 + 1 + n + 1 + 1, 2 + n + 2, 3 + n + 3,

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Features of Blind&Buried Via Hole PCB


Blind Via Hole is the connection between the outermost circuit in the PCB and the adjacent inner layer with a plated hole. Because the opposite side cannot be seen, it is called blind pass. In order to increase the space utilization between the circuit layers of the board, blind holes come in handy. The blind hole is a via hole to the surface of the printed board.

Buried Via Hole, the connection between any circuit layers in the PCB, but there is no conduction with the outer layer, that is, there is no meaning of a via hole extending to the surface of the circuit board.


The blind holes are located on the top and bottom surfaces of the circuit board and have a certain depth. They are used to connect the surface layer circuits to the inner layer circuits below. The depth of the holes generally has a prescribed ratio (aperture). This manufacturing method requires special attention, and the drilling depth must be just right. Failure to pay attention will cause difficulties in plating inside the hole. Therefore, few factories will adopt this production method. In fact, it is possible to drill the holes of the circuit layers that need to be connected beforehand, and then glue them together, but they need more precise positioning and alignment devices.


This manufacturing process cannot be achieved by bonding the circuit boards and then drilling. It is necessary to perform the drilling operation at the individual circuit layer, firstly locally bond the inner layer, then perform plating treatment, and finally all the bonding. Because the operation process is more laborious than the original vias and blind holes, the price is also the most expensive. This manufacturing process is usually only used for high-density circuit boards, increasing the space utilization of other circuit layers.


In the PCB manufacturing process, drilling is very important. The simple understanding of drilling is to drill the required via holes on the copper clad board, which has the function of providing electrical connections and fixing devices. If the operation of the via is caused by incorrect operation, the device cannot be fixed on the circuit board, which will affect the use of the circuit board, and the entire board will be scrapped. Therefore, the process of drilling is very important.

Parameters of Blind&Buried Via Hole PCB

Max board size580X700mm
Boar MaterialFR-4,Aluminum, High Tg  FR4,CEM3,etc.
Min trace width/ space (inner layer)4mil/4mil(0.1mm/0.1mm)
Min PAD (inner layer)5 mil(0.13mm)
Min thickness(inner layer)4 mil(0.1mm)
Inner copper thickness0.5~4 oz
Outer copper thickness0.4~6 oz
Finished board thickness0.4-3.2 mm
Board thickness tolerance control±0.10 mm±0.10 mm
Inner layer treatmentbrown oxidation
Layer count Capability1-30 LAYER
alignment between ML±2mil
Drill hole diameter0.15mm-0.65mm
Aspect ratio of plated hole10:01
Hole precision±2 mil(±0.05mm)
tolerance for Slot±3 mil(±0.75mm)
Hole diameter tolerance(PTH)±3 mil(±0.075mm)
Hole diameter tolerance(NPTH)±1mil(±0.025mm)
Max Aspect Ratio for PTH8:01
Hole wall copper thickness15-50um
Alignment of outer layers4mil/4mil
Min trace width/space for outer layer4mil/4mil
Tolerance of Etching+/-10%
Thickness of solder maskon trace
Thickness of solder maskat trace corner≥0.2mil(5um)
Hardness of solder maskOn base material≤+1.2mil
6HFinished thickness
Alignment of solder mask film±2mil(+/-50um)
Min width of solder mask bridge4mil(100um)
Max hole with solder plug0.5mm
Surface treatmentHAL (Lead or Lead free), immersion Gold, Immersion Nickel, Electric Gold finger, plated Gold, OSP, Immersion Silver.carbon oil,etc.
Max Nickel thickness for Gold finger280u"(7um)
Max gold thickness for Gold finger30u"(0.75um)
Nickel thickness in Immersion Gold120u"/240u"(3um/6um)
Gold thickness in Immersion Gold2u"/6u"(0.05um/0.15um)
Impedance control and its tolerance50±10%,75±10%,100±10% 110±10%
Trace Anti-stripped strength≥61B/in(≥107g/mm)
bow and twist0.75%
Inquiry Form
Relevant Customized Case Recommendation
Production flow chart
Q: Delivery terms and time?
A: We will ship the goods by DHL, TNT, Fedex, UPS or Aramex.the order can be sent out within 7-30 days depend on your order quantity, customization.
Q: What about OEM and ODM? and what is the MOQ?
A: We accept both OEM and ODM orders..MOQ is 1 pcs.
Q: Packing?
A: Flexible packing according to the specific requirements of the clients.
Sales office: 4F,Wangdefu International Building, Wanjiali Road, Furong District, Changsha City, Hunan Province
+86-183 1234 0501