The Hidden "Highway Network": How PCBs Are Powering Our Electronic World

October 30, 2025

Hello everyone! Today, we continue our easy-to-understand science series to talk about the "skeleton" of electronic products—the PCB (Printed Circuit Board). It's like a city's highway network, allowing electronic components (resistors, capacitors, inductors, ICs, power devices, connectors, etc.) to "traffic" smoothly (conduct electricity), forming complete functional circuits.

If you've ever played with building blocks, think of a PCB as the baseplate for electronic blocks. All components are inserted onto it and connected via copper traces. Without it, your mobile phones, computers, and game consoles would all become a pile of scattered parts!

Next, in a relaxed and fun way, we'll quickly guide you to understand PCB materials, processes, functions, and types. Oh, and also the environmental regulations!

1. What is a PCB? — The "Skeleton" of Electronic Products

(1) Function: Making electronic components "hold hands"
Without a PCB, electronic components are like a pile of scattered Lego blocks, unable to function properly. The copper traces on the PCB act like "wires," connecting the components to form a complete circuit.

(2) Structure: A multi-layer design like a "Sandwich"
A PCB is typically made of several layers of material laminated together:
Substrate (Insulating layer): Usually FR-4 fiberglass (like cardboard, but fire-resistant).
Copper Layer (Conductive layer): Etched with circuit traces (like drawing lines on paper).
Solder Mask (Protective layer): The green/blue/black "paint" that prevents short circuits.
Silkscreen (Marking layer): Prints text and symbols (e.g., R1, C2) to help engineers identify parts.

Here's an example: Imagine a PCB is like a pizza:
Crust = Substrate (Insulates)
Cheese = Copper Layer (Conducts)
Tomato Sauce = Solder Mask (Protects)
Toppings (Sausage/Veggies) = Electronic Components (Resistors, Capacitors, etc.)

2. Types of PCBs — Single-Sided, Double-Sided, Multi-Layer

PCBs are categorized into several types based on the number of layers and materials used.
For example:

Your TV remote? → Probably a single-sided board (simple and cheap).
Your smartphone motherboard? → Definitely a multi-layer board (at least 6-8 layers, super complex).
The cable in a foldable screen phone? → Flexible PCB (can bend hundreds of times without breaking).

3. How are PCBs Made? — 5 Steps from Design to Finished Product

PCB manufacturing is like baking a cake, done step by step:

(1) Drawing the Circuit Diagram (PCB Design)
Engineers use software like Altium Designer or KiCad to draw the circuit. It's like using CAD for architectural blueprints, but for drawing copper traces.

(2) Printing onto the Copper Clad Board (Photolithography)
The design is printed onto a copper-clad laminate. Unwanted copper is etched away using UV light and chemicals, like using a stencil to spray paint, leaving the desired pattern.

(3) Drilling (Making Holes for Components)
Holes are drilled for inserting electronic components (resistors, capacitors, etc.). Some holes are vias (connecting copper layers on different levels).

(4) Copper Plating (Making Holes Conductive)
The inner walls of the holes are plated with copper to allow electrical connection between different circuit layers.

(5) Soldering Components (Assembly)
Components are soldered using solder paste and reflow soldering (machine heating at high temperatures). Or by hand soldering (like when you tinker with Arduino).

Here's an example: PCB manufacturing is like making a pizza: Design the layout (decide toppings) → Lay the crust (substrate) → Spread sauce (copper layer) → Add toppings (drilling + soldering components) → Baking (reflow soldering).

4. Environmental Regulations — PCB Production Must Not Pollute the Earth!

PCB production involves chemicals and heavy metals, so it must comply with environmental standards:

(1) RoHS Certification (Lead-Free, Cadmium-Free)
Bans the use of toxic substances like lead, cadmium, and mercury (solder used to contain lead, now lead-free solder is used).

(2) WEEE (Waste Electrical and Electronic Equipment Recycling)
PCBs from old phones and computers must be properly recycled, not discarded randomly (heavy metals can contaminate soil).

(3) Green PCB?
Many PCB solder masks are green, but they can actually be red, blue, black, white... Green is most common mainly due to historical convention (early military PCBs used green).

5. Summary: PCB Quick Reference Guide

Remember this saying: "The baseplate for electronic blocks, connected by copper traces, multi-layered like a pastry, all governed by RoHS for environmental concerns!"

Now, when you look at your phone or computer, can you imagine what the PCB inside looks like?