Thursday 12 September 2013

What Goes Into Manufacturing Of PCB

By Helene Norris


Printed circuit boards, otherwise known as PCB are found in almost all electronic devices. In manufacturing of PCB, electricians who are amateurs can make their own boards by drawing a design and then giving it to the manufacturer. There are three types; single sided, multi layered and double side boards. They are usually conducted with nickel, copper or aluminum material, and the type used is determined by the complexity and density of the circuits. The process of making them is described below.

The backing is first plated with a conductive material. Holes are then drilled into it in order for conduction to take place in between the layers and also to mount electronic components. The board is then scrubbed to get rid of any small particles of the conductor. Such particles can be later on recycled from the water by using a process such as filtration. Any copper particles left behind can easily mix with other wastes and become pollutant to the environment.

The board is then cleaned. Etching also takes place to allow for proper adhesion in the next stage. Once this has been carried out, there is an addition of another layer of conductor. The process of electrolysis copper plating is applied in order to conduct the holes that had been drilled previously. Both alkaline based and acidic based solutions such as copper sulfate can be used to enhance pH balance.

Photo imaging is used to achieve the final design of the circuit. The final thickness is also arrived at by electroplating copper. Protection of the final circuits in the next etching is quite vital and hence, a thin layer of tin or lead solder should be applied. The copper will not form the final circuit and should therefore be removed. Sulfuric acid or a solution containing ammonia is used to etch away the unwanted copper.

Obtaining alternative resist can be achieved by use of other compounds that are photosensitive or organic. They can be used in their dry or wet forms. When exposed to ultraviolet light, they become hard.

In order to spread the liquid resist, one can use a silk screen, squeegee, roller or spray. One or both sides can have the liquid on. However, application can also be done to a specific area on the surface. Finer circuits can be produced by use of light.

The last stage in this process is forming multi layer panels. The layer's inner cores are assembled together. The resulting product is like a book which has a copper foil with sheets of epoxy that are alternating.

The book is then placed in a lamination press and high heat and pressure applied to it. The epoxy layers will melt and form a bond. An oven is used to cure the panel. It also undergoes trimming and buffing and then the required holes are finally drilled into it. Summarily, manufacturing of PCB requires a careful and properly calculated procedure in order to achieve the desired results.




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