A printed circuit board popularly known as PCB is the first thing you would require when you decide to build an electronic circuit. A proper PCB design ensure that various circuit components are interconnected as per the circuit diagrams once they have been placed on the PCB in their proper positions and subsequently soldered. Simple circuits can sometimes assembles without PCB. However your collage project work may a little bit complicated and you will surely need to design and etch the pcb of your own circuit. This post will share some basic pcb layout design rules that you need to know before proceeding.
LAYOUT DESIGN
Layout design is the first step of the PCB design and it is a rough design of the artwork which contains some proper information for preparing pcb artwork. For the preparation of layout, the pcb designer should have the following information.
- Physical size of each component
- Pin configuration details of components (Transistor, IC etc)
- Design rule for particular application (Analog or Digital)
- Preferable size of PCB
- Termination of connection
LAYOUT SCALE
Depending upon the accuracy of the designed circuit board required, layout should be produced at 1:1, 2:1 or 4:1 scale. The 4:1 scale is used only when high precision is required. 2:1 scale is commonly used. After completing the layout, it should be reduced to 1:1 scale photographically.
LAYOUT PROCEDURE
- Prepare component layout first as viewing from the component side.
- Layout should be prepared in the direction of signal flow as far as possible
- Among the electronic components, larger ones are placed first and the space in between them is filled with smaller components like resistors, small transistors, diodes.
- Components that require input-output connection are placed near the connectors or pcb edge.
- All components are placed in the printed circuit board in such a manner that desoldering of the other components is necessary if they have to be replaced.
- The electronic circuit can be sub-divided into functional subunits and each subunit is realized on a defenite position of the board.
- While preparing the layout, it is a common practice to draw conductor lines only on graph sheet.
- Spacing between the components must be uniform and it must be checked when the conductor passes between pcb pads.
- For critical signal parts, optimum precaution have to be taken such as minimum conductor length guard lines and clear separation of input and output lines etc.
- Components producing considerable heat have to be identified on the circuit diagram so as to avoid concentrated heat on the circuit board.
- To identify the conductor lines on layout for double sided PCB's, pencils of different colour's can be used. Another possibility is to draw all of them with an ordinary pencil, but to draw interrupted lines for conductors on one of the side.
