Printed Circuit Boards: the Basics

PCBsupplierChina talk Printed circuit boards are typically made from laminated composite material.This non-conductive substrate sandwiches copper circuitry that actually makes up the circuits the boards are named after.

These copper circuits, also known as signal traces, electrically connect and mechanically support other mounted components on the board.

Why are PCBs green?That’s actually the solder mask showing up through the fibreglass core of the board.Solder protects the copper circuits and prevents short circuits.The green solder casts a tint on the glass pieces protecting it.

solder mask: /ˈsädər mask/;a protective layer of liquid photo imagable lacquer that has been applied to the top and bottom of PCBs to protect copper from oxidation and dust.

How To Identify Components Step-by-Step

Identify the Parts

Next, identify passive components like capacitors and inductors.Don’t worry, we’ll have pictures later in this post.Then look for resistors and potentiometers.These will usually have an ohm measurement mark.The symbol for an ohm is the Greek letter Omega, which looks like this: Ω.100MΩ translates to 100 megaohms.

Other easy-to-identify components include oscillators (cylinders or boxes typically marked with X or Y), transformers (T), diodes (D), and relays (marked as K).

Now look to see if the board has a fuse.Fuses are often clear or opaque tubes.Then try to identify any batteries or transistors.

Identify any board connectors.Connectors are used to attach other circuit boards or to attach the board to a larger system or outside components.

There are so many different kinds of connectors you could spend months learning them all, but the most common are backplanes, terminal blocks, pin headers and the sockets that accept them, and jacks or plugs.

Finally, identify the processor and other integrated circuits on the board.Many ICs will have their manufacturer and part number label or ID.If so, you may be able to look up an individual datasheet to learn more about the chip.

Printed Circuit Boards: Most Common Components

While PCBs can have many different mounted components, eight make up the most common. These include：

Batteries.In most cases, batteries will be marked as “BT.” Batteries provide backup stored power.

Capacitors.Marked “C”.Capacitors store energy, and are rated in farads.This is usually written as microfarads ( µF) or millifarads (mF).

Diodes.Marked D or CR. Zener diodes may be marked Z or ZD.These regulate voltages.

Inductors.Marked L. Inductor coils store energy in a magnetic field as electric current flows through.

LEDs.Light-emitting diodes.Marked LED.LEDs convert electrical energy into light.

Resistors.Marked R. Resistors reduce current flow, adjust signal levels, divide voltages, and terminate transmission lines.They can also dissipate watts of electrical power as heat.

Switches Marked S. You use switches every day.Just like a light switch or your car ignition, these switches are used to turn things on or off.

Transistors.Marked Q. Transistors are a type of semiconductor.They amplify and rectify signals.Why are they represented by Q?

FPCmanufacturer talk because when they first came into use (the 1950s) transformers had already taken the (T) designation.Plus, people honestly didn’t know if they were going to be useful enough to stick around.So (Q) seemed good enough.