An overview of the method used for manufacturing PCBs
An overview of the method used formanufacturing PCBsManufacturing of PCBs (printed circuit board) is a complexprocess and the first step of electronics manufacturing services.There are three types of circuit boards; single sided, double sidedand multi-layered. Complexity, density and the spatialrequirements are the deciding factor of which type of circuit tobe used.
Method of PCB manufacturingUsually nonconductive materials are used for the backing of boards.Conductive materials are used for the coating of circuit boards suchas aluminum, nickel and copper. Here’s a brief look at the method ofPCB manufacturing:Drilling & scrubbing the boards:Once the backing has been platedwith conductive material, holes are drilled to allow other electroniccomponents to be mounted over it. After drilling the holes, boardsare scrubbed to remove tiny conductor particles. Electricallyconductive materials like copper are recycled and recovered fromthe water waste with the help of filtration process or via centrifuge.
Etching process:In this process, the boards are first cleaned. After that,they are etched for better adhesion in the following steps. Next stepinvolves adding another conducting layer. Since the holes that were drilledin the earlier stage are not electrically conducive, hence for the purpose ofcoating the holes with a conductive material, a process like electrolysiscopper plating is employed.Getting final thickness:Photo imaging is used for making the final designof circuit. Electroplating copper is used for obtaining the final thickness ofprinted board. A very thin layer of lead or tin solder resist is applied forprotecting final circuit in next stage of etching. The plating is then removedin the next stage to expose the copper which will not be a part of the finalcircuit. Hydrogen-peroxide or sulfuric acid is used to remove unwantedcopper material.
Alternative resists:Volatile compounds or photosensitive materials canalso be used as other types of resists. They can be applied either dry orwet. These photosensitive compounds get hard when they are exposed toUV light. Various techniques are used for applying liquid resists such asroller, squeegee, spray or silk screen. The liquid may be applied on eitherboth sides or on a particular surface area.Multi-layered PCB panels:These panels are made by assembling innerlayers. These panels are then assembled as alternate epoxy sheet layersand copper foil layers. This book-like structure is then placed forlamination under high pressure. This results in melting of epoxy layers,and release of adhesive bond. This is followed by drilling of necessaryholes.This was an overview of a conventionally used method for producing PCBboards by electronics manufacturing company.