Printed circuit boards (PCBs) are the backbone of nearly every electronic device, but what exactly is a PCB made of? Understanding PCB materials isn’t just useful for engineers—it’s critical for OEMs, sourcing managers, and product designers in any B2B setting. But here’s the kicker… material selection directly impacts electrical performance, cost, thermal stability, and even compliance with safety regulations. In this Jerico Multilayer PCB supplier writed guide, we’ll peel back every layer of a PCB, from substrates and copper to solder masks and specialty compounds. If you’ve ever wondered what your boards are really made of, this is your complete breakdown.

 

1. Introduction to PCB Composition

Let’s get started by unpacking the PCB’s material anatomy.

A PCB is more than just a flat green board. It’s a carefully engineered sandwich of materials—each chosen for its specific function. You’ve got substrates to hold everything together, copper for electrical connectivity, solder masks for protection, and silkscreens for guidance. Each layer serves a purpose, and using the wrong material can lead to heat failure, signal distortion, or regulatory noncompliance.

But what’s the real story? Most people don’t realize how tailored each board’s composition can be. A high-frequency telecom board will look nothing like a consumer gadget board. Likewise, military PCBs often include exotic, heat-resistant compounds.

Whether you’re designing for automotive, medical, or IoT, the right mix of materials determines everything from signal clarity to longevity. That’s why it pays to get familiar with what a PCB is made of—because when you understand your layers, you build a better product.

PCB Layer	Material Function	Typical Materials Used
Substrate	Structural base	FR4, polyimide, ceramic
Conductive Layer	Electrical signal routing	Copper foil
Dielectric	Insulation between layers	Epoxy resin, ceramic blend
Solder Mask	Protection & insulation	Epoxy, LPI green mask
Silkscreen	Component labeling	Epoxy-based white ink
Finish Layer	Surface protection & soldering	ENIG, HASL, OSP

2. What Is PCB Made Of, Core Structure of a Standard PCB

Ready for the good part? The heart of any PCB is its multi-layered structure.

A standard PCB typically consists of a non-conductive substrate, one or more layers of copper foil, a solder mask, silkscreen markings, and a surface finish. The number of copper layers may vary depending on the application—from simple single-sided PCBs to complex 12+ layer multilayer boards.

The inner core, usually made from FR4, gives the board rigidity and strength. On either side of this core, copper layers are laminated under high pressure and temperature. Dielectric layers separate each copper sheet to prevent short circuits. Over these, the solder mask protects traces from corrosion and shorts. Finally, a silkscreen helps identify components during assembly.

But here’s the kicker… even small changes in this stack-up can affect signal integrity, impedance, and thermal performance. That’s why material selection isn’t just cosmetic—it’s critical engineering.

For example, a medical-grade ECG monitor might use a 6-layer board with a polyimide core for flexibility and biocompatibility. In contrast, a consumer router may use a 2-layer FR4 stack with ENIG finish for cost-effectiveness.

Layer	Purpose	Material Example
Core Substrate	Mechanical stability	FR4, polyimide, ceramic
Copper Layer	Signal/power transmission	Electro-deposited copper
Prepreg (dielectric)	Electrical insulation	Epoxy resin
Solder Mask	Oxidation & short prevention	LPI green mask
Silkscreen	Labeling/assembly aid	White epoxy ink
Surface Finish	Solderability & protection	HASL, ENIG, OSP

3. Substrate Materials Used in PCBs

Now, let’s dive into the real foundation of your PCB.

The substrate forms the physical base of the board, and its characteristics determine how well your PCB handles heat, vibration, moisture, and frequency. The most common material? FR4, a flame-retardant woven glass epoxy laminate. But depending on the application, other materials may be better suited.

Here’s the key point: Substrate selection is not about choosing the most expensive or the cheapest option—it’s about finding the best fit for your product’s requirements.

Let’s break it down:

Comparison of Common Substrate Materials

Substrate Type	Key Properties	Ideal Applications	Cost Level
FR4	Flame-retardant, cost-effective, good electrical insulation	Consumer electronics, industrial controls	Low
CEM-1/CEM-3	Low cost, moderate strength, cellulose-epoxy blend	Lighting, toys, low-end electronics	Very Low
Polyimide	High-temperature resistance, flexible, excellent durability	Aerospace, automotive, flexible circuits	High
Ceramic	Extreme heat resistance, superior RF performance	Military, high-power modules, RF/microwave	Very High

Key Takeaways:

• FR4 is the most economical for general-purpose applications.
• Polyimide is ideal where flexibility and high-temperature stability are critical.
• Ceramic is unmatched for high-frequency or extreme environments but comes at a premium cost.
• CEM-1/CEM-3 is suitable for cost-sensitive, low-performance devices.

Remember: The best material isn’t necessarily the most expensive—it’s the one that aligns with your product’s electrical, thermal, and mechanical demands while balancing cost efficiency.

4. Copper Foil Layers and Their Function

Let’s move up the stack—literally.

The copper foil is what makes the PCB conduct. These layers form the electrical paths (traces) between components. Without them, your PCB is just a pretty plastic sheet. But here’s the kicker… copper thickness, purity, and patterning all affect performance.

Typically, copper is laminated onto the substrate via heat and adhesive. The standard thickness is 1 oz (35μm), but you’ll see 0.5 oz to 6 oz used depending on the current load.

Thicker copper = higher current handling. That’s why power electronics, EV charging modules, and industrial motor controllers use heavy copper boards.

Three examples:

1. A USB keyboard might only need 0.5 oz copper for signal transmission.
2. A power supply PCB for an LED panel may use 2 oz copper to prevent overheating.
3. An automotive ECU may require 3–4 oz for consistent voltage across layers.

Copper Thickness	Typical Use Case	Notes
0.5 oz	Signal transmission, low power	Great for cost savings
1 oz	Standard in most PCBs	Balanced performance
2 oz	LED, motor drivers, battery PCBs	Better heat management
3+ oz	Industrial power & automotive	Specialized, more expensive

5. Dielectric and Insulating Layers

Let’s talk insulation—it’s not just about heat; it’s about safety and signal integrity.

Dielectric layers separate copper traces to prevent short circuits and allow multilayer PCBs to function without interference. But here’s where it gets interesting… the material and thickness of these layers affect capacitance, impedance, and even EMI performance.

Common dielectric materials include:

● Epoxy Resin: Most widely used with FR4. It’s cost-effective and thermally stable up to 130°C.

● Ceramic-filled PTFE: Used in RF and microwave applications. Offers high signal integrity and low loss.

● Rogers Materials: Known for consistent dielectric constants and low dissipation. Ideal for aerospace and telecom.

Three real-world examples:

1. A 4G LTE base station uses low-loss PTFE-based dielectrics for reduced signal loss.
2. A server motherboard employs FR4-based epoxy dielectric for standard impedance control.
3. A satellite module might use Rogers RO4350B dielectric for stable performance at 10GHz+.

Dielectric Type	Dielectric Constant (Dk)	Application
FR4 (Epoxy)	~4.2–4.5	Standard electronics
Ceramic-filled PTFE	~2.2–2.5	High-frequency RF/microwave
Rogers RO4350B	3.48	Aerospace, telecom
Polyimide	~3.4	Flex PCBs and extreme temps

6. Solder Mask Layer Explained

Now, let’s address that iconic green layer—what is it and why does it matter?

The solder mask is more than a pretty coat. It insulates copper traces, prevents oxidation, and reduces the risk of solder bridging during assembly. But here’s the kicker… while green is the industry default, it’s far from the only option.

Manufacturers now offer solder masks in red, black, white, blue, and even transparent for aesthetic or identification purposes. What doesn’t change is the need for precision. Solder mask misalignment can cause short circuits or exposed copper that corrodes.

Most solder masks are LPI (Liquid Photo-Imageable) epoxy, cured under UV light. Some advanced boards use dry film masks for better edge definition in high-density layouts.

Three use cases:

1. Consumer gadgets (like phones) use LPI green for standard cost-effective protection.
2. Medical devices often choose white masks for component visibility and cleanliness.
3. Gaming motherboards might use red or black for branding and aesthetics.

Solder Mask Color	Common Use Cases	Notes
Green	Industry standard	Excellent contrast and durability
White	LED, medical devices	Reflects light well
Black	Aesthetic products	Shows dust and scratches easily
Blue/Red	Branding, prototypes	Visual differentiation

7. Silkscreen Layer and Markings

The silkscreen might not carry electricity—but it carries clarity.

Used for printing text, logos, reference designators, and orientation indicators, silkscreen ensures your PCB is readable during assembly and servicing. But here’s the real story… it also plays a huge role in post-manufacturing quality control and documentation.

Silkscreen is usually applied using epoxy-based white ink, though black and yellow are common on non-green solder masks. Ink is cured after printing to resist wear during handling and soldering.

Three examples:

1. A router PCB has reference numbers printed for every capacitor, simplifying troubleshooting.
2. A power converter uses silkscreen to mark warning zones and test points.
3. A branding PCB features a custom logo printed in gold ink for display products.

Best practices include keeping silkscreen away from pads, ensuring font size >0.8mm, and using high-contrast colors.

Silkscreen Feature	Purpose	Best Practice
Reference Designators	Assembly aid	Place near each component
Polarization Marks	Orientation help	Essential for diodes/ICs
Company Logo/Labels	Branding, identification	Avoid copper pad areas

8. Surface Finishes for Copper Pads

Now let’s talk about the finishing touch.

The copper pads on your PCB need protection—both from oxidation and poor solderability. That’s where surface finishes come in. Ready for the good part?

There are several finish options, each with strengths and tradeoffs:

● HASL (Hot Air Solder Leveling): Inexpensive, easy to inspect. Not ideal for fine-pitch components.

● ENIG (Electroless Nickel Immersion Gold): Flat, solderable, long-lasting. Slightly more expensive but perfect for BGA packages.

● OSP (Organic Solderability Preservative): Low cost, environmentally friendly, but limited shelf life.

Three real-world cases:

1. A smartwatch PCB uses ENIG for its fine-pitch ICs and surface mount pads.
2. An LED light board opts for HASL due to its cost efficiency and through-hole components.
3. A tablet prototype uses OSP for rapid assembly and short-term testing.

Surface Finish	Cost	Shelf Life	Flatness	Best For
HASL	Low	Moderate	Fair	Through-hole boards
ENIG	High	Long	Excellent	High-density SMT, BGAs
OSP	Very Low	Short	Excellent	Prototyping, cost-sensitive

 At Jerico Multilayer PCB Supplier, when receiving customer design files, our engineering team frequently provides expert recommendations on the optimal surface finish

9. Conductive Inks and Traces in Flexible PCBs

What happens when copper can’t flex? Enter conductive ink.

Used primarily in flexible PCBs and printed electronics, conductive inks (silver, carbon, or copper-based) are screen-printed or inkjet-deposited onto flexible substrates. They allow circuits to bend, twist, and stretch where traditional copper would crack.

But here’s the kicker… their resistivity is higher than etched copper, making them ideal for low-current, space-saving applications.

Three application examples:

1. Wearable fitness trackers use printed carbon traces on polyester film.
2. Automotive dashboards deploy silver ink circuits behind curved displays.
3. Smart packaging uses ultra-thin copper nanoparticle ink for NFC chips.

Ink Type	Conductivity	Typical Use Case
Silver-based	Very high	Wearables, antennas
Carbon-based	Moderate	Pressure sensors, buttons
Copper nanoparticle	High	Thin-film IoT, printed RFID

10. Material Choices for High-Frequency PCBs

Let’s turn up the speed—literally.

High-frequency applications, especially in telecom and RF, demand specialized materials that minimize signal loss and ensure signal integrity. But what’s the real story? Standard FR4 just doesn’t cut it when GHz speeds are involved.

Instead, you’ll find materials like:

● Rogers laminates: These offer low dielectric loss and tight Dk tolerances, ideal for RF and microwave circuits.

● Teflon (PTFE): Has outstanding electrical properties and is often used for satellite, radar, and aerospace boards.

● Ceramic composites: Provide exceptional heat resistance and are used in military and space-grade systems.

Three practical examples:

1. A 5G antenna board made with Rogers 4003C to reduce insertion loss at 3.5GHz.
2. A satellite communication board using PTFE to maintain signal integrity over long distances.
3. An industrial IoT gateway using a ceramic hybrid laminate to manage thermal loads and EMI.

High-Frequency Material	Dielectric Constant (Dk)	Best Use Cases
Rogers 4003C	3.55	5G, automotive radar
Teflon (PTFE)	~2.1–2.5	Aerospace, RF devices
Ceramic Hybrid	~6.5–10+	High-temp, military

11. Thermal Management Materials

Now it’s getting hot—literally.

Thermal performance is mission-critical in power electronics, LED lighting, automotive ECUs, and high-speed data systems. But here’s the kicker… without proper materials, PCBs can warp, degrade, or even fail catastrophically under thermal stress.

Enter thermal management solutions:

● Aluminum-core PCBs: Combine a thermally conductive core with traditional copper to efficiently spread heat away from components.

● Thermal vias: Copper-plated through-holes connecting layers that conduct heat vertically toward heatsinks or external chassis.

● Ceramic PCBs: Offer unmatched thermal conductivity and are ideal for high-power, high-density modules.

Three use cases:

1. An LED floodlight uses an aluminum-backed PCB to maintain light output consistency and lifespan.
2. An EV battery monitoring system employs thermal vias to disperse heat from the BMS ICs.
3. A server-grade VRM (voltage regulator module) includes ceramic-filled prepreg to reduce hotspots.

Thermal Material Type	Thermal Conductivity (W/mK)	Common Use
Aluminum Core	~1–5	LEDs, power supplies
Thermal Vias	Variable	BGA, MOSFETs, processors
Ceramic Substrate	~20–200	RF amplifiers, power ICs

12. Environmental and RoHS-Compliant Materials

It’s time to get green—literally and legally.

The electronics industry is under increasing pressure to eliminate hazardous materials. That means your PCB materials must now comply with standards like RoHS, REACH, and WEEE. But here’s where it gets interesting… compliance is about more than ticking boxes—it’s about futureproofing your brand.

Key considerations:

● Halogen-Free Laminates: Reduce smoke and toxicity during combustion, especially in consumer and public-space devices.

● Lead-Free Finishes: ENIG and lead-free HASL are now preferred over traditional SnPb HASL in most regions.

● Low-VOC Solder Masks: Some eco-conscious manufacturers are switching to environmentally safe curing agents and resins.

Examples of compliant applications:

1. A children’s toy PCB uses halogen-free FR4 and OSP finish to meet EU RoHS requirements.
2. A telecom server motherboard features REACH-compliant epoxy and ENIG finish for global shipment.
3. A smart home device manufacturer requires UL94-V0 halogen-free material for all PCB enclosures.

Compliance Type	Banned/Regulated Elements	Material Alternatives
RoHS	Pb, Hg, Cd, Cr6+, PBB, PBDE	Lead-free HASL, halogen-free FR4
REACH	SVHC (Substances of Very High Concern)	Low-toxicity resins
WEEE	Product recyclability	Modular PCB design

13. Specialty Materials for Unique Applications

Sometimes, standard materials just won’t do.

Special applications demand special materials—and printed circuit boards can be tailored for extreme conditions, high complexity, or unusual form factors. Ready for the good part?

● HDI PCBs: Use microvias, stacked vias, and ultra-thin prepregs for compact designs like smartphones, tablets, and wearable tech.

● Rigid-Flex Materials: Combine rigid FR4 sections with flexible polyimide tails for dynamic applications like medical catheters or aerospace panels.

● Space/Aero-Grade Materials: Use low-outgassing compounds, thermally stable resins, and advanced laminates like Teflon-glass composites.

Three practical examples:

1. A defense drone control PCB integrates rigid-flex with polyimide and stacked microvias.
2. A high-speed digital camera uses HDI material to support its dense 20-layer FPGA board.
3. A Mars rover PCB uses space-grade laminate that resists extreme UV and vacuum conditions.

Specialty PCB Type	Key Material Used	Application
HDI PCB	Laser-drilled vias, thin cores	Smartphones, wearables
Rigid-Flex PCB	FR4 + Polyimide	Aerospace, surgical tools
Aerospace/Military	Low outgassing epoxy/glass	Satellites, aircraft

14. Impact of Material Selection on PCB Cost

Let’s talk numbers—what does it all cost?

Material selection is the number one cost variable in PCB manufacturing. But here’s the kicker… the cheapest material isn’t always the most cost-effective. Poor choices can lead to field failures, redesigns, and lost customer trust.

Main cost influencers:

● Base Material: FR4 is the most affordable. Rogers, polyimide, and ceramics are more expensive but offer superior performance.

● Copper Weight: Thicker copper costs more per square inch. High-power designs will increase copper demand significantly.

● Surface Finish: HASL is cheap, ENIG is premium. The choice affects both cost and assembly success.

● Layer Count: Each added layer requires extra dielectric and copper, increasing both material and processing time.

Material Factor	Low-Cost Option	Premium Option	% Cost Difference
Substrate	FR4	Rogers, ceramic	+30–200%
Finish	HASL	ENIG, immersion Ag	+20–60%
Copper Weight	1 oz	3–4 oz	+25–50%
Layers	2	8–12	+100–300%

15. Summary of PCB Material Layers and Their Role

Let’s wrap it all up with a bow.

Every layer in a printed circuit board plays a role—mechanical, electrical, thermal, or visual. From the substrate that forms its skeleton to the silkscreen that communicates its identity, understanding what a PCB is made of empowers you to design smarter, source better, and manufacture more reliably.

Remember: the ideal mix of materials depends on your product’s demands. There’s no one-size-fits-all approach, but with this breakdown, you can speak confidently with engineers, suppliers, and clients alike.

Use this as your cheat sheet during sourcing conversations or technical meetings—it’s the foundation for building exceptional, cost-effective, and compliant PCBs.

PCB Layer	Function	Common Materials
Substrate	Mechanical foundation	FR4, polyimide, ceramic
Copper Layer	Signal and power paths	0.5–6 oz copper foil
Dielectric	Electrical insulation	Epoxy, PTFE, ceramic
Solder Mask	Oxidation and bridging protection	LPI epoxy mask
Silkscreen	Component guidance	White/black epoxy ink
Surface Finish	Solderability and longevity	ENIG, HASL, OSP

FAQ Section

• Q1:what are pcb made of?
  A PCB is made of layers including a non-conductive substrate (like FR4), copper foil, a solder mask layer, silkscreen markings, and sometimes a surface finish like ENIG or HASL.
• Q2: How does the substrate material affect a PCB?
  The substrate determines the board’s strength, flexibility, heat resistance, and dielectric properties, influencing overall performance and application suitability.
• Q3: What is the purpose of the solder mask in a PCB?
  The solder mask protects copper traces from oxidation, prevents solder bridging during assembly, and gives the PCB its color (usually green).
• Q4: Why are there different surface finishes on PCBs?
  Surface finishes like ENIG, HASL, or OSP protect copper pads and improve solderability, with each type suiting different assembly and storage needs.
• Q5: Are PCBs environmentally friendly?
  Modern PCBs can be made with RoHS- and REACH-compliant materials, using halogen-free laminates and lead-free finishes to reduce environmental impact.