Designing process of printed circuit boards

Designing Process Of
Printed Circuit Boards

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Designing Process Of Printed Circuit
Boards
Introduction:
 The most vital element in electronic circuits and equipment's is the
Printed Circuit Board (PCB). It is also possible to build an electronic
circuit with bread boards and zero boards, but the method is a low level
and less efficient one wherein the designing circuit is prone to damage
and the designing involves a complex process of placing the components
of the circuit.

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What is a Printed Circuit Board?
 Electronic circuits in engineering and industry are normally manufactured
by using printed circuit boards (PCBs).
 These boards are made up of special materials.
 That do not conduct electricity such as fiber and glass.
 The circuits are designed on the boards with copper tracks.
 Instead of wires for the conduction of electricity between the electronic
components.

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 The electronic components are fixed in their respective positions.
 By drilling holes on the board, placing the components.
 Then soldering them in appropriate positions so that the copper
tracks and components together form a circuit.
 It offer quick functioning, access, control, monitoring and precise
and exact results when compared to other wiring methods based
devices.

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 The printed circuit boards used in all electronic products such as
o Automotives
o Wireless Devices
o Robotic applications

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The below figure shows how the circuit is arranged on a PCB with
copper layer.
555 Timer PCB Circuit 555 Timer Printed Circuit Board

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Designing Process of a
PCB
 There are numerous ways available for designing PCBs.
 Circuit board design can be manufactured as bulk using several machines in
PCB fabrication industries Including .
o Drilling
o Punching
o Plating

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Designing Process of a
PCB
o Laser drilling with CNC machines
o Automatic plating machines
o Strip etching machines
 Use of optical inspection equipments, flying probe testers for electrical
testing of printed circuit board process result in high-quality PCBs (with a
greater production yield).
 Final fabrication processes that are performed through highly automated
machines.

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Step1: Design the PCB Circuit With a Software
 Draw the schematic circuit diagram with the PCB layout software.
 Using CAD software, Eagle and Multisim software.
 This type of PCB design software contains a library of components that
can be used to build the circuit.
 It allows your to change the circuit design’s position ,modification
according to your convenience and requirement.

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 We have selected Eagle software to design the circuit and its procedure is
as follows:
o Open the Eagle circuit board design software.
o A window with a menu bar appears.
o Click on the file menu.
o Select ‘new design’ from the drop-down menu.
o Click on the library menu.

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o Select ‘pick devices/symbol’ from the drop-down menu.
o Select a relevant comment by double clicking on it.
o so that the component appears on the window.
o Add all the components and draw the circuit with proper connections
as shown in the figure.

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 Enter the rating of each component according to the requirement.
 Go to Command Toolbar and click Text editor varriages, click on the
Varriages, and then close the window.
 Next, a black screen appears which is of the layout or the film diagram of
the circuit as shown in the below figure, and save this as an image format.

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Step2: Film generation
 The film is generated from the finalized circuit board diagram of the
PCB layout software which is send to the manufacturing unit where
the negative image or mask is printed out on a plastic sheet.

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Step3: Select Raw Material
 The bulk of the printed circuit board is made with an unbreakable glass
or fiberglass.
 Having copper foil bonded unto one or both the sides of the board.
 The PCBs made from unbreakable paper phenolic with a bonded
copper foil.
 These are less expensive and are often used in household electrical
devices.

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Step3: Select Raw Material
 Mostly 0.059 industry standard thick, copper clad laminate, either
single or double sided board is required.
 Panels may be sheared to contain May boards of different sizes.

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Step4: Preparing Drill Holes
 Machines and carbide drills are used to put holes on the printed
circuit board.
 There are two types of machines available to drill the PCBs.
 They include hand machines and CNC machines.
 The hand machines require human intervention or effort to drill the
holes.
 CNC machines are computer-based machines.

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 It work-based on the machine timetables or programs that run both
automatic as well as manually.
 The drilled pattern is stored in the computer like drill bit sizes, number of
holes per panel, drilled stack, drilled time per load, etc.
 The PCB boards are placed into the CNC machine.
 The holes are drilled according to the determined pattern to place
printed circuit board components.

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Step5: Apply Image
 The printed circuit layout can be printed in different ways on PCBs like.
o Manual pen.
o Dry transfers.
o Pen plotters and printers.
 The laser printers are a better way to print the layouts on printed circuit
boards.

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Step5: Apply Image

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Step5: Apply Image
 The following steps are used to print the PCB layout through a laser printer:
o Take a clean and neat copper paper and place it on the laser printer.
o Next, store the designed layout film in the computer.
o A laser printer prints the designed circuit layout on a copper paper
whenever it gets a print command from the computer.

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Step6: Stripping and Etching
 Stripping and Etching process involves removing the unwired copper on
the PCBs.
 Using different types of chemicals like ferric chloride, ammonium per-
sulphate, etc.
 Make the solvent by mixing 1% of sodium hydroxide and 10 grams of
sodium hydroxide pellets to one litre of water.
 Mix the composition until everything is dissolved.

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Step6: Stripping and Etching
 The PCB is put on a chemical bowl and cleaned up with a brush.
 During this process, if the PCB is still greasy, due to applied sunflower
or seed oil, the developing process may take about 1 minute.

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Step7: Testing
 After finishing the manufacturing process of the Printed Circuit Board.
 The Board undergoes a testing process to check whether the PCB is
working properly.
 Nowadays many automatic testing equipments are available for the
high volume testing of the PCBs.
 The two different types of testing equipment available today .

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Step7: Testing
 That test your circuit boards include ATG test machines that are flying
probe.
 Fixtureless testers and in addition to a universal grid testing capability as
well.

Conclusion
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 The invention of the PCB that supports physical electronic
components and their wiring through the surface-mounted copper
tracks is really remarkable. Printed circuit boards, PCBs, form an
essential part of any electronics equipment these days. The PCB
design and layout forms an integral part of the design of the whole
product, and it can be the key to the success of the product meeting
its performance requirements in many instances.

Designing process of printed circuit boards

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Designing process of printed circuit boards