How to Design PCB Layout? - Guidelines, Advantages and Disadvantages

How to Design PCB Layout - Guidelines, Advantage and Disadvantage

The PCBs are designed today with the help of software. Readymade layout details, dimensions of electronic components are available which can be a part of the software. Manually also it is possible if it is less complex. Layout design is the main process of PCB design.

Layout design is the proces of creating the blue print of the actual PCB, Layout file contains the information on different components present, their physical appearance (foot print), the component placement, interconnecting among the components, number of layer for interconnections etc. for the PCB. The foot print is a pictorial representation of a component when it is looked from the top top (Top view). It is a 1:1 representation. Some of the readily available packages for ICs are, SIP, DIP, EIP, SOIC, QEP etc. Routes are the interconnection among the pins/leads of various components. It is called copper track. The width of the tracks are to be choses properly. Layers are the multiple planes used for performing routing a peration. In a multi-layer board, the interconnection among various layers is provided through conductive drill holes. These drill holes are known as via. The marking text and graphics provide information like part number, board name, graphics outline of components, etc. Generally marking text and graphics is carried out on PCB after fabrication on silk screen. 

Also read - What is printed circuit board and Types?

Guidelines for PCB Layout :

• The PCB manufacturer fabrication PCB as per layout files. An inefficient layout leads to an inefficient PCB. Following guidelines are to be followed for PCB layout. 

• Keeping the physical size of the PCB in mind. Place the components inside the layout area within board outline.

• The component to component distance is to be kept minimum.

• Place the connectors towords the edge of PCB. 

• Keep the number of layers minimum. Use lesser number of vias in the boards.

• Use appropriate track width for signal line and power lines.

• Keep the distance between two adjacent tracks minimum.

• Avoid sharp edge of the tracks.

• Provide neat and easily understandable assembly notes.

• For double side component mounting. Consider the component height and clearance between the bottom side of PCB and the enclosure.

Advantages of PCB :

There are several advantages of assembling electronic circuits in printed circuit boards.

• Compact in size and saving of wire : The number of inter connections are reduced and size is reduced.

• Miniaturisation : The components being miniaturized. PCB is the only choice as it allows compressed and efficient way of organizing electronic components.

• Tight connections and avoid short circuits : No chance of loose connections or short circuits as compared to peer to peer connections. 

• Ease of repair and diagnostics : PCB allows easier replacement of damaged components. Diagnostics also becomes simple.

• Saving of time : The conventional peer to peer method of circuit building is time consuming where PCB circuit assembly is fast process and it can be automated.

• Immune to loose connections and movement : Components fitted on PCB are fix and fit, hence immune to movements. 

• Low electronic noise : PCB designed is done carefully hence circuits on PCB cause less electronic noise.

• Los cost : Mass production is a very low cost (scalability).

• Reliability More due to above factors.

Disadvantages of PCB : 

• PCBs are not suitable for heavy current flow.

• Production process - etching, causes environmental degradation.

• Specific PCB can be used for that fixed and specific purpose only.