Acronym for Printed circuit board, PCB finds its application in electronics and is highly cost effective and offer more reliability as compared to other circuits like point to point circuits or wire wrapped circuits. Though the manufacturing process of a PCB is a complicated one as it involves high initial investments, the results are highly rewarding.
PCB support electronic components mechanically and connects them electrically via copper etched traces, conductive pathways on a non conductive substrate and is also known as etched wiring or printed wiring board.
There are three methods that are commonly used by the manufacturers of PCB’s & these differ in the subtractive methods. The process involves the bonding of a copper layer on either or both the sides of a full substrate. After this process the excess copper or undesired copper is removed completely whilst the necessary copper is retained with the help of a temporary mask.
The most common methods used by the PCB manufacturing companies in the subtractive process of PCBS are as follows:
Photo Engraving – This process makes use of a photo mask as well as chemical etching for removing the unwanted copper from the substrate. This photo mask is created with the help of a photo plotter that is again created by a technician through computer based manufacturing software.
Silk Screen Printing – This subtractive method employs etch resistant ink on the important parts and protects the requisite copper foils, while at the same time the etching process removes the unwanted or undesirable copper.
Pcb Milling – A PCB prototype is used for milling away the undesirable copper foil from the substrate. This system is also referred to as two or three axis mechanical milling system and works the same way as the plotter and the commands are transmitted via the host software that control the positions of all the three axis.
Lamination – The lamination process involves the bonding of multiple thin trace layers or etched boards, also referred to as multi layer printed circuits.
Drilling – Drilling is done to connect every single layer of the PCB with the other layer by drilling holes called VIAS with the help of an automated drilling machine. These drills are driven by the computer and are also known as numerically controlled drills or excellon files. Every wall of a multi layered board is copper plated forming plate through holes connecting the conductive layers of PCB.