What are the Inclusions in a PCB fabrication drawing?

A PCB Fabrication drawing refers to an ultra-critical file that carries information pertaining to the actual construction of the circuit board. The extent of thorough work put in drawing the PCB fabrication drawing increases the probabilities of obtaining a circuit board to fit your specifications. A fabrication drawing defines certain parameters like layer stack up, board outline, drill chart and a lot of other features. An effective assembly drawing coupled with a fabrication drawing is very helpful in assembling the circuit board.

What do all these terms mean? Specifically, what is the relation between a PCB Fabrication Drawing and an Assembly Drawing?

Since the name has it, a fabrication drawing entails important information that is compulsory in putting up the board. An assembly drawing on the other hand describes all the necessary details as to how each component shall connect to the board.

There are certain elements that should be included in a PCB fabrication drawing.

Dimensions

That is why it is necessary to mention the dimensions of the board as that will provide an understanding of how much PCB material will be needed to cover the board.

• Length of the board
• Its width
• Thickness
• Outline
• Tolerances

There also has to be a Board Outline and it instructs where the cuts have to be made, the holes, the radii, and other distances from the origin and the like.

• Drill chart       
• Which layers need drilling
• Drill Sizes
• Tolerance, and more.

The drill chart contains certain symbols associated with the hole size. It gives information on whether the inside of the holes are plated or not and much more.

Layer Stack Up

This is a clear indication that Layer Stack up has a lot of influence on some of the other facets of the project.

• Material
• Thickness
• Copper Weight
• Surface Finish
• Tolerances
• Controlled Impedance

Based on the Controlled Impedance specification, the manufacturer can then consider other aspects such as dielectric constant, spacing, trace width and more.

In a wide variety of software, the PCB Fabrication drawing can be created. But,it is not limited to:  

• Eagle EDA
• KiCAD
• Altium Designer
• PCB Fabrication Notes

With the following information, it will help to include PCB Fabrication notes in addition:

• Requirements of Controlled Impedance
• Manufacturing specifications
• Raw material specifications
• Plating details
• Details of Solder Mask
• Gold fingers, if present
• Any specifications concerning the position of holes.
• If via-in-pad exists then mention
• Blind/Buried via, if any
• Some more tolerance includes board tolerance & plating & etching tolerance.

With today’s modern methods of PCB manufacturing, why not have the best PCB manufacturing solutions. Even better, the PCB Fabrication services will be taken up a notch from the specialists here as they will accept all kinds of the newest technologies.

Next: Know About the High-Density Interconnect (HDI) Flexible PCBs