Michigan State University College of Engineering

ECE 480 Team 7

Ryan Lupinski

11/08/13

The purpose of this tutorial is to guide a person through the process of creating a working printed circuit board (PCB) using the free software PCB Artist from 4PCB.com. The tutorial will give a brief introduction to the tool followed by a step by step process of selecting components in the component library, designing a circuit schematic, and finally laying out the schematic to a PCB.

Background

PCB Artist is a free PCB schematic and layout tool provided by Advanced Circuits. It is an intuitive and simple program that includes a large library to select components from while also allowing users to create their own symbols. A drawback, however, is the program’s omission of Gerber (.gbr) files, that are universal fabrication files, but a .fab file. This requires the user to order directly from Advanced Circuits.

PCB functionality

PCB’s are made of ‘layers’. The common PCB will have 2 or 4 layers, consisting of metal layers, silkscreen layers, and solder mask layers. Components are placed on the upper-most layer and traces will run from connection pads on the component to various components, supplies, ground, etc. The use of multiple layers gives dimensional flexibility to the user by being able to jump up and down from layers to avoid crossing traces on a single layer. ‘Footprints’ for the surface connection of components are created and the user can specify how the metal traces connect each component. When the user is satisfied with the layout, the board and it’s layers and traces are fabricated and sent to the user so they may populate the board by soldering components to their proper ‘footprint’ on the board.

Beginning a project

To begin a new project open PCB artist then go File->New. Select the option for a New Project and create a proper path to save the project. You must follow the same process to add a New Schematic and New PCB Design, and select ‘Add To Open Project’ for each. This is shown in Figure 1. This combines the Project (.pjr), Schematic (.sch), and PCB (.pcb) files together for consistency.

Figure 1. (left to right) New Project, New Schematic, New PCB Design

Creating a schematic

A schematic is a symbolic representation of a circuit the user wishes to design. PCB artist offers a wide range of components in its Component Library and also offers the user a “Wizard” if they want to create a custom symbol. This tutorial will not cover the creation of custom symbols. Figure 2 shows a blank schematic and numbers corresponding to [1] the add component button, [2] the component library, [3] and the trace button. For this tutorial, a simple low pass filter will be created using an OPA33AIDG4 op amp.

Figure 2 Schematic design space

The first step is to select your component by either clicking the ‘add component’ button [1] seen in Figure 2. Figure 3 shows the Add component pop up window and the Find pop up window which can help you search a component by name.

Figure 3. Add component window and Find window

The next step is the hit close on the Find pop up window and then click add in the Add Component library. Lastly you can position the component symbol in the Schematic design space. Now minor components such as resistors and capacitors can be added to the schematic. These can be found using the same process, but rather than searching OPA333 in the find window, the user can search resistor or capacitor. Once all the components are selected and added to the Schematic design area, the connections between the components can be made. Figure 4 shows both a complete and incomplete connection between component and wire nodes that connect the feedback loop of the op amp through the resistor. Wiring components together can be done by clicking on the trace button [3] in Figure 2 and then drawing a path between two components.

Figure 4. Complete and incomplete wiring

Once all the components are placed in the design space in a logical pattern and wired properly the user can send the schematic to PCB layout. The final low pass circuit schematic can be seen in Figure 5.

Figure 5. Fully populated schematic

Creating the PCB

The next step is to transfer the schematic to PCB layout. This is done from the schematic design space by selecting Tool>SchematicßàPCB>Translate to PCB. Figure 6 shows the PCB Design Setup wizard that will walk the user through PCB specifications.

Figure 6. PCB Design Setup Wizard

Set units to ‘mils’ and precision to ‘0’ and select Use Board Template. The next step lets the user select a 2 or 4 layer board. This tutorial will proceed with a 2 lay set up. Hitting next until arriving at the Production stage uses default values for layers and additional parameters. The user can specify other values during the set up if desired. Figure 7 shows the production step where the board will be named, turnaround time selected, quantity selected, and pricing will be shown. These can be changed as desired and 5 days turnaround time is the recommend selection for time and cost purposes.

Figure 7. Production step of set up wizard

Hit next and chose to have components placed outside of the board. The user may now drag components into the green region and begin making trace connections. Figure 8 shows components placed on the board. Yellow ‘rubber bands’ indicate connections that need to be made.

Figure 8 Arranged components with connection indicators

Components can be rearranged and traces between them can be made. Traces are copper paths that allow for electrical connection between components. Traces on common layers MUST NOT OVERLAP. The use of 2 layers allows for a bottom layer to be used as ground or another plane for traces to jump between layers by use of a via. Figure 9 shows a complete 2 layer board.

Figure 9 Completed Low pass filter PCB

The blue layer shows the bottom layer of the PCB which has been dedicated to ground. This allows for any connection made through a via (the small yellow circles) to connect the top layer to the bottom layer. It can be noted that the GND symbol at the top has connections to the bottom layer by allowing the blue region of copper (ground) to have traces over the connection. This creates a common ground for the board. This concludes the design of the PCB and is now ready for fabrication.