Page 16 - Make Your Own PCBs with EAGLE from Schematic Designs to Finished Boards

FIGURE 1-1 Anatomy of a double-sided PCB.

• Pads are where the components are soldered to the PCB.

• Tracks are the copper tracks that connect pads together.
• Vias are small holes through the board that link a bottom and top track together electrically.
Tracks on the same layer cannot cross, so often, when you are laying out a PCB, you need a

signal to jump from one layer to another.
• Silk-screening refers to any lettering that will appear on the final board. It is common to label

components and the outline of where they fit so that when it comes to soldering the board
together, it is easy to see where everything fits.
• Stop mask is a layer of insulating lacquer that covers both sides of the board except where

there are pads.

Surface Mount and Through Hole

Pads are either though hole, where components with leads are pushed through from the top, soldered
underneath, and then the excess lead snipped off, or surface mount, where the components are
soldered to the top of the pad. Figure 1-2 shows a board that contains both surface-mount and
through-hole components.