Bare Board:

A finished PCB that has had no components added.

Blind Via: A via hole that does not pass completely through the printed circuit board. A blind via starts from one side or another.

Buried Via: A buried via connects two or more inner layers but no outer layer, and cannot be seen from either side of the board.

Copper Foil - as used in the manufacture of PCBs:

The copper foil used in the manufacture of multilayer printed circuit boards is Electrodeposited copper foil. There are several different thicknesses of copper foil that can be used depending on the application of the printed circuit board.

Copper foil is measured in Ounces per square foot or Grams per m²

The standard copper foils are:

• ½ Ounce Copper Foil or 153g m² or 17 microns

• 1 Ounce Copper Foil or 305g m² or 35 microns

• 2 Ounce Copper Foil or 710g m² or 70 microns

The thicker the copper foil the more current the copper will be able to carry and the lower the impedance characteristic will be . As a rough guide, each doubling of copper foil thickness allows an increase of about 1.4 times current capacity.

Etching

The process of selectively removing any material not protected by a resist using an appropriate solvent or acid.

A brief description of FR4

FR4 is a general grade laminate made of woven fibreglass fabric saturated with an epoxy resin. This laminate is used in both double sided materials and multilayer base materials. FR4 has the best physical, thermal and electrical properties of all of the laminates for many circuit board applications.

Gerber

Gerber is a format designed by Gerber Scientific for use with their Photoplotters. The Printed Circuit industry has adopted it as a standard because of the flexible and reliable way in which it can be used for Photo plotting Printed Circuit artworks.

Photoresist

A light sensitive liquid or a film, which when selectively exposed to light, masks off areas of the design that can then be etched away.

Photoplotter

A device for generating photographic images by directing a controlled-light beam that directly exposes a light-sensitive material.

Plated Through Hole

A hole in which electrical connection is made between internal or external conductive patterns, or both, by the plating of metal on the wall of the hole.

Pre-preg - description

In it's simplest form pre-preg is the glue that holds the separate layers of a multilayer circuit board together. There are different types of pre-preg that can be used depending on the finished board thickness being built and the amount of copper that has to be encapsulated.

Solder Mask

A coating applied over selected areas of a circuit board thereby permitting soldering only of the exposed (uncoated) areas, usually only the pads

Solder resist:

Coating material used to mask or protect selected areas of a pattern from the action of an etchant, solder, or plating.

Surface Mount Technology:

(SMT). The components are mounted on the surface of a circuit board rather than inserting components into plated through holes.

Via:

A plated through hole used as a through hole connection between the layers on a circuit board. These holes are generally the smallest as no components are inserted in them.

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