Printed Circuit Board (PCB)

A printed circuit board, or PCB, is used to mechanically support and electrically connect electronic components using conductive pathways, or traces, etched from copper sheets laminated onto a non-conductive substrate. Alternative names are printed wiring board (PWB), and etched wiring board. A PCB populated with electronic components is a printed circuit assembly (PCA), also known as a printed circuit board assembly (PCBA).

PCBs are rugged, inexpensive, and can be highly reliable. They require much more layout effort and higher initial cost than either wire-wrapped or point-to-point constructed circuits, but are much cheaper and faster for high-volume production. Much of the electronics industry's PCB design, assembly, and quality control needs are set by standards that are published by the IPC organization.

The example for PCB Layout Program
Materials

Conducting layers are typically made of thin copper foil. Insulating materials have a wider scale: phenolic paper, glass fibre and different plastics are commonly used. Usually PCB factories use prepregs (short for preimpregnated), which are a combination of glass fibber mat, no woven material and resin. Copper foil and prepreg are typically laminated together with epoxy resin. Well known prepreg materials used in the PCB industry are FR-2 (Phenolic cotton paper), FR-3 (Cotton paper and epoxy), FR-4 (Woven glass and epoxy), FR-5 (Woven glass and epoxy), and FR-6 (Matte glass and polyester).

Patterning (etching)

The vast majority of printed circuit boards are made by bonding a layer of copper over the entire substrate, sometimes on both sides, (creating a "blank PCB") then removing unwanted copper after applying a temporary mask (e.g. by etching), leaving only the desired copper traces. A few PCBs are made by adding traces to the bare substrate (or a substrate with a very thin layer of copper) usually by a complex process of multiple electroplating steps.

The etching machine
Lamination

Some PCBs have trace layers inside the PCB and are called multi-layer PCBs. These are formed by bonding together separately etched thin boards

Printed circuit assembly

After the printed circuit board (PCB) is completed, electronic components must be attached to form a functional printed circuit assembly, or PCA (sometimes called a "printed circuit board assembly" PCBA). In through-hole construction, component leads are inserted in holes. In surface-mount construction, the components are placed on pads or lands on the outer surfaces of the PCB. In both kinds of construction, component leads are electrically and mechanically fixed to the board with a molten metal solder.

Protel 99 SE As PCB Design Tools

With Protel 99 SE we can take any design from the simplest 3 component circuit through to the most complex multi-sheet project, from concept to completion. Protel 99 SE includes an easy-to-use schematic capture editor with a huge range of components, a powerful PCB design editor with sophisticated interactive routing and placement features that are second-to-none, and an easy-to-use shape based auto router that routes like a professional board designer.

To back up these core design tools Protel 99 SE also includes a SPICE 3f5 compliant mixed-signal circuit simulator, a CUPL-based PLD compiler, and a sophisticated PCB signal integrity analysis tool. Nowadays, the usage of Protel 99SE is no longer available.

Footnote : This information is based on my assignment.