FAQ about PCBs

As a Printed Circuit Board supplier, we receive many technical questions regarding the PCB fabrication. Here you can find our FAQ about PCBs. If you can't find an answer for your question, please, contact the office near you so we can assist with your needs.

What specifications are required to build a PCB?

Gerber file or ODB++ and customer specification/technical data sheet.

What is Tenting (Tented Vias)? How to apply?

Tenting in PCB means covering the annular ring and via hole with solder mask. Tented Vias are those that are completely covered with solder mask. 

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. 

Where can I find the PCB Connect Group capabilities?

You can find our capabilities for Rigid, Flex Rigid, HDI and Flexible PCBs here in the following link: www.pcbconnectgroup.com/pcb-connect-capabilities/

What should be contained in the Technical Specifications?

When you fill the specifications in your RFQ, you should specify:

  • Layer Count
  • Surface Treatment
  • Board Size
  • Panel Size
  • Boards/Pni
  • Material
  • Board Thickness
  • Solder Mask Color
  • Legend Print
  • Production Specification
  • Other important specification, if it's needed.
What is the difference between “Plugging Vias” and “Tented Vias”?

Materials are different. Tented Vias use dry film solder mask, Plugging Vias use liquid solder mask or resin. Also, Plugging Vias allows partial material penetrate into the via, but Tented Vias just need to bridge over vias wherein no additional materials are in the hole.

What is the difference between CEM1, CEM3, ALU and FR4?

FR4 is the most common material grade that used for fabricated circuit boards. ‘FR’ indicates the material is flame retardant and the ‘4’ indicates woven glass reinforced epoxy resin

CEM-1 is low-cost, flame-retardant, cellulose-paper-based laminate with only one layer of woven glass fabric.

CEM-2 has cellulose paper core and woven glass fabric surface.

CEM-3 is very similar to the most commonly used PCB material, FR-4.

What are the thermal coefficients of aluminum PCBs?

IPC 4101E define thermal conductivity level for aluminum PCB as below:

Level A ≤1.0

Level B >1.0 ≤2.0

Level C >2.0 ≤3.0

Level D >3.0 ≤5.0


What are the IPC-4101 classifications?
IPC-4101 99 101 121 124 126 127 128 129 130
Tg (min) C 150 110 110 150 170 110 150 170 170
Td (min) C 325 310 310 325 340 310 325 340 340
CTE Z 50-260 C 3,5% 4% 4% 3,50% 3% 4% 3,50% 3,50% 3%
T260 (min) minutes 30 30 30 30 30 30 30 30 30
T288 (min) minutes 5 5 5 5 15 5 5 15 15
Fillers > 5% Yes Yes NA NA Yes Yes Yes NA Yes
Dk/Permittivity (max) 5,4 5,4 5,4 5,4 5,4 5,4 5,4 5,4 5,4
What is “peelable solder mask”?

The "peelable solder mask" it's a liquid and (also known as strippable mask or blue-mask) is applied by screen-printing, act as in-process protection and are removed after processing at the assembler.
It provides printed circuit boards with protection in soldering processes like wave soldering, selective soldering or at the PCB level a surface finish protection.

What is the difference between Initial and Final Copper?

Initial copper means base copper which come from the laminate we buy. Final copper means the copper thickness for the finished PCB , it include base copper and plating copper.

Does PCB Connect comply with the RoHS Directive?

Yes, our factory comply with RoHS Directive.

RoHS stands for Restriction of Certain Hazardous Substances.  It is an European legislation that bans six hazardous substances from manufacturing processes: cadmium (Cd), mercury (Hg), hexavalent chromium (Cr (VI)), polybrominated biphenyls (PBBs), polybrominated diphenyl ethers (PBDEs) and lead (Pb).

How long is the shelf life of the boards? Have different expiration dates between materials (Hasl, OSP, ENIG, etc)?

PCB shelf life were defined based on PCB surface finishes, IPC define PCB shelf life as below:

HASL - 12 months
HASL lead free - 12 months
ENIG - 12months
ENEPIG - 12months
Immersion Silver - 6 months
Immersion Tin - 6 months
OSP - 6 months

What does it mean “mouse bite” and “V-Cut”?

Mouse bite holes are designed in panel for facilitating separate PCB from frame, it is normally design in two rows, refer to below picture

V-cut is also called V-Scoring, it is used for mechanical pre-separation of circuit boards.

V-cut can only be performed along straight line ,A V-shaped breaking line is formed in the circuit board with a precision cutting tool.
Performing V-cut is just for PCB separation become easily .

What is FR4 in PCB?

FR4 is the most popular type of material in the PCB manufacturing. FR4 material is ideal to produce one layer PCB or multilayer PCB. It suits for demands for flexible or rigid PCBs as well.

What is a Multilayer PCB?

Multilayer PCB is a printed circuit board that has more than, at least, four layers, with one or multiple conductor patterns inside the board. You can see our Multilayer Capability here.

What is a HDI pcb?

The HDI - High Density Interconnector PCBs have a higher wiring density compared with standard PCBs. Check our HDI sheet capability here.

What is Flexible PCB?

Flexible printed circuit boards are boards that uses flexible based material in your applications. They can be single or double sided up to 6 layers. You can check our Flex Capability here.

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