Generally we are listening the words PCB’s, PCB layout, PCB designing, ect. But what is PCB? Why we are using this PCB? We want to know about all these things as a electronic engineer. PCB means Printed Circuit Board. This is a circuit board with printed copper layout connections. These PCB’s are two types. One is dotted PCB and another one is layout PCB. The two examples are shown in below.
Fig. 1:Typical Image of Dotted PCB and Layout PCB
What is the main difference between the dotted PCB and layout PCB? In dotted PCB board only dots are available. According to our requirement we can place or insert the components in those holes and attach the components with wires and soldering lid. In this dotted PCB we can make the circuit as out wish but it is very hard to design. There are so many difficulties are there. Those are connecting the proper pins, avoiding shot connections and etc. Coming to the layout PCB this is simple to design. First we select the our circuit and by using different PCB designing software’s, design the layout of the circuit and by itching process preparing the copper layout of our circuit and solder the components in the correct places. It is simple to design, take less time to design, no shortages, looking nice and perfect.
Up to now we have discussed about types of PCB’s and difference between the types. Now we can discuss about PCB designing software. There are so many PCB designing softwares available. Some are Express PCB, eagle PCB, PCB Elegance, free PCB, open circuit design, zenith PCB and Proteus etc. Apart from remaining Proteus is different. Proteus is design suit and PCB layout designing software. In Proteus we can design any circuit and simulate the circuit and make PCB layout for that circuit.
Introduction to Proteus:
Proteus professional is a software combination of ISIS schematic capture program and ARES PCB layout program. This is a powerful and integrated development environment. Tools in this suit are very easy to use and these tools are very useful in education and professional PCB designing. As professional PCB designing software with integrated space based auto router, it provides features such as fully featured schematic capture, highly configurable design rules, interactive SPICE circuit simulator, extensive support for power planes, industry standard CADCAM & ODB++ output and integrated 3D viewer.
Up to know we have discussed about the basics and software description. Now we are entering into the designing section. Run the ISIS professional program by clicking the icon on the desktop, then this splash screen will appear.
Fig. 2:Screenshot of Launch Window of Proteus Design Suite
Next, a work space with interface buttons for designing circuit will appear as shown in figure below. Note that there is a blue rectangular line in the workspace; make sure that whole circuit is designed inside the rectangular space.
Fig. 3:Screenshot of IDE of Proteus Design Suite
Next step is selecting the components to our required circuit. Let us take one example is designing of 38 kHz frequency generator by using 555 timer IC. The circuit diagram is shown in below image.
Fig. 4:Circuit Diagram of 555 IC based 38 KHz Frequency Generator
In the above circuit the required components are 555 timer IC, 470? and 22K? resisters, 10K? variable resister, 0.001µf capacitor and one IR LED. So select the components from library. In menu bar library > pick device/ symbol. Then one window will open that shown in below.
Fig. 5:Screenshot of Device Selector on Proteus
There is another way to select the components. In work space left side there is a tool bar. In that tool bar click the component mode button or pick from library.
Fig. 6:Screenshot of Component Mode Button on Proteus
Select the all components from library, that components are added to devices list. Click on the device and change the angle of the device by using rotate buttons. Then click in the work space then the selected component is placed in work space. Place all the devices in work space and put the curser at the component pin end then draw the connections with that pen symbol. Connect all the components according to circuit then that designed circuit is show in below image.
Fig. 7:Screenshot of Sample Circuit designed on Proteus
If any modifications want to do to the component place the mouse point and click on right button then option window will open. That is shown in below figure.
Fig. 8:Screenshot of circuit modifications on Proteus
After completion of designing save with some mane and debug it. This is virtual simulation means without making circuit we can see the result in virtually through this software and we can design the PCB layout to our required circuit with this software.
PCB Layout Designing
Now we are going to design a PCB layout for the above circuit. Proteus has the integrated ARES PCB designing suit. By using this we can easily develop the PCB layout. After simulation save the circuit designing and click on tools then select netlist to ARES. Then a window will open with list of component packages. That is shown in below image.
Fig. 9:Screenshot of Tools Menu on Proteus
Fig. 10:Screenshot of Work Space on Proteus
Then next step is creating a board edge by selecting 2D graphics box mode. Next click on the select layer at bottom left corner and select the board edge option. The image is shown in below figure.
Fig. 11:Screenshot of 2D graphics Box on Proteus
Then next click on work space then a green line will appear. With that draw a box and click again once. Then the box is fixed and turn into yellow color layout. This box is same like in above ISIS professional blue line. The circuit should be inside of the yellow box. If the circuit is more complex and big in size, the there is a chance to expand the box by clicking on the select mode. Then next click on the component name and change the angle of the component by using rotation arrow options if required. Then place the component on the work space. After adding the all components to the work space, arrange the position of the components properly in the workspace. To move component one place to another place click on selection mode and click on component then it change color with white and hold the component and moved to required place within the yellow box. After placing the all components in correct position, next thing is tracking. Tracking means establishing the connection between the components with copper layer. First select the track mode by clicking the track mode button, and change the track width by clicking ‘C’ create or ‘E’ edit buttons shown in the below image. When we click the button C or E immediately a window will open. Select the width of the track from given list. It is better to select between 25, 40. Electronic hobbyists made their required PCB’s at their home or lab. At that time track width in case less than 25, there is a chance of occur cuts in tracks. The less width is useful in computer based PCB layering. So hobbyists are making their PCB’s their own. So the width should be greater than 25. My suggestion is the width should be 35.
Fig. 12:Screenshot of PCB Layering on Proteus
Then next thing is create tracks between components. Connection representation in green line and yellow line shows the direction. After setting the track width click at the component one end with pen and follow the green line. When two components are successfully connected then green line will removed automatically.
Another main thing is there are several PCB’s are available. Those are single layer PCB, duel layer PCB, multi layer PCB. In single layer PCB components are placed at one side and connections (tracking) done in another side. Coming to duel layer PCB, tracking is done in two sides and components are placed in two sides also. In this type mostly SMD components are used. Next finally multi layered PCB’s, in these many layers are used. In this two are top and bottom layers and remaining all are inner layers. In Proteus we can design up to 16 layers PCB. One is top layer, another one is bottom layer and remaining all are inner layers. The layer selection in Proteus is at left down corner. Each layer will represent in different color. For example bottom layer represented in blue color, top layer represented in red and inner layers are represented in different colors. The image shown in below figure.
Fig. 13:Screenshot of Layout designing on Proteus
In the above image, it shows that track is placed between R1-2 pin and RV1-1pin. Another thing is placing the track from 6th pin to 3rd pin. The direction is indicating in white arrow mark. Connection is indicating in green line and blue line indicates the track. If any contact errors occurred while tracking, those are represented in red circles and the image shown in below figure.
Fig. 14:Screenshot of PCB Layout on Proteus
In the above image red color represented circles are errors occurred while tracking. To avoid such errors change the track path. Like this arrange the tracks between the all pins without errors. If you are planning for duel layer PCB, there is short cut for changing the track layers from one layer to another that is press the mouse left button two times immediately turned into another layer. In above image there is an orange circle. That represents the ‘via’ means placing connection between one layer to another layer. There is an advantage in Proteus. That is auto-router. This is special tool to arrange tracks automatically without errors. But this tool creates duel layer PCB. When we select this tool, automatically shape based auto router window will open. This window having the execution mode, design rules and grid width changing options. By changing all options according to our requirement and click the button begin routing automatically routing will start.
Fig. 15:Screenshot of Auto Router on Proteus
In above second image red tracks indicate top copper and blue tracks indicate bottom tracks. This is duel layer PCB designing. If we want single layer PCB, we can place tracks out own. The given below image shows the single layer PCB design of our required circuit. After completion of tracking save the project in same folder where the above Proteus project saved. In Proteus we have one other tool that how the circuit is been looking like after completion.
Fig. 16:Screenshot of Auto Routed PCB Layout on Proteus
To see the final circuit, click on output in menu bar and then select 3D visualization. Then the circuit visualization will open in other window. It is having the features of all angles visualization, components less board view and back layer view. That is shown in below figure.
Fig. 17:Screenshot of 3D View of Circuit on Proteus
Next this is the final step of PCB layer designing, which is layout printing. Taking prints of board layer is the final step. So to take print of the circuit layout, click on output in menu bar and click on print. Then print layout setup window will open.
Fig. 18:Screenshot of Print Layout Window on Proteus
In that window all layer selection options, modes, path, rotation options, scale, reflection and image preview available. Coming to modes it is having the four modes those are artwork, solder resist, SMT mask and drill plot. In artwork mode all our work means tracks and components view means in above images yellow color module view can take print. While printing the bottom copper layer one important thing is there, that is reflection selection. That should be selected in mirror mode. The window is shown in below figure. We have to take many prints of the circuit layout.
PCB Layout Printing
1.Top copper layer printout. It is no need to this because this is single layer PCB. It is only for duel layer PCB.
2. Bottom copper layer printout. While printing this layer except bottom copper and board edge remaining all boxes will unselect position in layers/artwork part. Next select the scale as 100%, select the rotation as X horizontal and the important thing is reflection should be select mirror. Because after printing this layer on paper it is placed on the copper board in opposite direction means the printed side should be faced to copper layer. That’s why we are selecting reflection as mirror.
Fig. 19:Image of PCB Layout Print for Sample Circuit
3.Top silk layer printout. This combination with bottom copper. In single layer PCB we are using only bottom copper. That means components are present in top side. So top silk layer prints the components view. This will prints the place of the components. While printing this layer except top silk and board edge remaining all boxes will unselect position in layers/artwork part. Remaining all selections is same except reflection. Reflection should be selected in normal mode.
Fig. 20:Image of Silk Layer Printout for Sample Circuit
4. Bottom silk layer printout. This is for duel layer PCB.
5.Solder resist layer printout. This is for preventing from short circuits. To print this layer select the mode as solder resist and click the bottom resist box and board edge and reflection mirror mode. Because this is also same like bottom copper layer printing.
Fig. 21:Image of Resist Layer Printout for Sample Circuit
6.SMT mark is not for this because in our circuit we don’t use the SMT modules.
7. Drill plot layer printing. This layer indicates the drill place and drill hole size. While printing this layer only drill and board edge boxes is in selected position. Reflection is normal mode.
Fig. 22:Image of Drill Dot Layer Printout for Sample Circuit
After printing the all layers next thing is PCB itching. That means copper tracks designing with layer printed paper.
1.Take the copper layered PCB board and cut the board according to our requirements.
2. Place the bottom copper layer printed paper on the copper PCB board by facing the printed surface to copper layer. The example shown in below figure.
Fig. 23:Image showing layout print placed over Layout PCB
3.Fix the paper and board without moving.
4. Apply heat by iron box or any other sources to the white printed paper.
5.At the printing machine carbon powder sprayed on white paper and applying heat, the model is scanned, according to that model carbon powder is stick on the paper and remaining powder on the paper is cleaned.
6. Here we are applying same process. Place the face of printed paper to copper layer and applying heat to it then the carbon power stick to copper layer. So the paper is merged with board.
7. Drop the board into water and remove paper slowly then the carbon layer fixed on copper board. That example image shown in below figure.
Fig. 24:Image of Copper Board with printed layout
8.Then drop the board into ferric-chloride liquid. Then the copper react with ferric-chloride and the copper which is not having carbon layer is dissolved in ferric-chloride and remaining part which is having the carbon layer that is not dissolved in ferric-chloride. That example image shown in below figure.
Fig. 25:Image of PCB Layout with printed Circuit
9. Next clean the board with sand paper. Erase or remove the carbon layer by scratching the board with sand paper. Then the carbon layer completely removed and copper layer shown out.
10. Make the holes by drilling according to drill position layer.
11.Then finally place the proper components in correct places and by using soldering kit fix the components to the board.
12. Then finally cut the extra pins come from holes by cutter. Then our circuit is ready.
Filed Under: Electronic Projects
Tagged With: pcb, pcb design, Proteus
