Circuit Board Composition and Material Composition of Electronic Components

Electronics are complex manufactured items that contain up to hundreds of homogeneous materials. Undoubtedly, technology evolves rapidly, and engineers invent new patents every day, with new materials! What is the circuit board composition and the material composition of some of the most common passive and active electronic components?

Circuit Board Composition

A bare circuit board composition is typically the following:

Epoxy
Copper
Flame retardants – FR-4
Surface finish – HASL, ENIG – lead, gold, etc.

On top of the circuit board composition, electronic devices are typically made of other components with many materials.

Material Composition of Passive Electronic Components

Resistors

There are many various types of resistors with different compositions. This table presents the most common types of resistors and gives examples of their material composition:

Types of Resistors	Structure and Examples of Material Composition
Carbon Composition Resistors (CCR)	Resistive element: A mixture of finely ground carbon particles and a non-conductive ceramic material (e.g., clay) Metallic end caps Leads made of copper wires Insulating material (e.g., plastic)
Metal Film Resistors	A thin metal (often nickel-chromium) layer as the resistive element sputtered on a high purity ceramic cylindrical core Metallic end caps Leads made of copper wires
Carbon Film Resistors	A carbon film or layer as the resistive element on a ceramic substrate Metallic end caps Leads made of copper wires Epoxy coating
Metal Oxide Film Resistors	A metal oxide (e.g., tin oxide with the additive of the antimony oxide) film as the resistive element coating the ceramic substrate Metallic end caps Leads made of copper wires
Wire-Wound Resistors (WW)	Resistive element: A metal wire (often nichrome or manganin) winding around a non-conductive material (e.g., plastic, ceramic, or fiberglass) core An insulating material covering wounded wire

Resource: Physics and Radio-Electronics

Resistors are one of the most common passive electronic components. The function of resistors in a circuit is to resist the flow of electrical current.

Capacitors

There are different types of capacitors based on their material compositions. This table describes the most common capacitors and gives examples of their composition:

Types of Capacitors	Structure and Examples of Material Composition
Plastic Film Capacitors	Two plastic films (e.g., polyester) as insulators layered with aluminum or zinc sheets as electrodes Lead connecting wires
Ceramic Capacitors	Ceramic as an insulator Conductive metals as electrodes Lead connecting wires
Aluminum Electrolytic Capacitors	Aluminum sheets Aluminum oxide as an insulator
Tantalum Electrolytic Capacitors	Tantalum powder Tantalum pentoxide as an insulator
Niobium Electrolytic Capacitors	Niobium or niobium oxide powder Niobium pentoxide as an insulator
Mica Capacitors	Mica (a phyllosilicate mineral) sheets as insulators layered with copper or aluminum metal sheets as electrodes A plastic case Lead connecting wires
Paper Capacitors	Two or more aluminum sheets as electrodes Paper sheets as insulators Lead connecting wires Wax or plastic resin coating

Resources:

Physics and Radio-Electronics
J.L. Stevens, A.C. Geiculescu, T.F. Strange, Dielectric Aluminum Oxides: Nano-Structural Features and Composites at the Wayback Machine
T. Kárník, Avx, Niobium Oxide For Capacitor Manufacturing, Metal 2008, 13. –15. 5. 2008

Capacitors are another example of passive electronic components. In electronic circuits, capacitors store energy in the form of an electrical charge and release it whenever required.

Inductors

There are different types of inductors based on the material composition of their cores. Here you can find examples of these materials:

Types of Inductors	Examples of Material Composition of Inductor’s Core
Air Core or Ceramic Core Inductors	Ceramic
Iron Core Inductors	Iron
Ferrite Core Inductors	Ferrite Manganese Zinc Nickel
Iron Powder Inductors	Iron powder mixed with a binder (e.g., epoxy or phenolic)
Laminated Core Inductors	Steel or other materials with insulating material

Resource: Electronics Hub – Types of Inductors and Applications.

Inductors store energy in the form of a magnetic field when an electric current passes through them. They consist of conducting material, normally insulated copper wire, winding around a core.

Material Composition of Active Electronic Components

Most active electronic components consist of semiconductors. Semiconductors possess electrical properties between conductors and insulators. The most commonly used material in semiconductors is silicon (Si). Other semiconductor materials in electronic devices are:

Germanium (Ge)
Gallium arsenide (GaAs)
Silicon carbide (SiC)
Gallium Nitride (GaN)
Gallium phosphide (GaP)
Cadmium sulfide (CdS)
Lead sulfide (PbS)

Resource: Electronics notes – Semiconductor Materials Types” Groups & Classifications

Transistors

The table below explains the structure of two types of transistors and gives examples of material compositions for each one:

Types of Transistors	Structure and Examples of Material Composition
Bipolar Transistors	A thin layer of p-type or n-type semiconductor material between two layers of the opposite type (PNP or NPN).P-type semiconductor: Composition of a pure semiconductor material (like Silicon or Germanium) and a small amount of trivalent impurity (like Boron (B), Gallium (Ga), Indium (In), Aluminum (Al)). N-type semiconductor: Composition of a pure semiconductor material (like Silicon or Germanium) and a small amount of pentavalent impurity (like Phosphorus (P), Arsenic (As), Antimony (Sb), Bismuth (Bi)).
Field Effect (Unipolar) Transistors	Two layers of a single type of semiconductor, either p-type or n-type (See above).

Resource: Engineering360 Transistor Information

A transistor is a semiconductor electronic component that can perform either as an amplifier or a switch. There are different types of transistors available in the market.

Diodes

Here you can find examples of material compositions of every element of a diode:

Types of Diode	Examples of Material Composition
Chip	Doped Silicon (Si)
Lead Frame	Ferrous Alloy composing of different materials like iron (Fe), Nickel (Ni), Manganese (Mn), Cobalt (Co), Silicon (Si), Chromium (Cr)
Lead Frame Plating	Silver (Ag)
Bond Wire	Gold or Silver Silicone
Lead Plating Finish	Matte Tin (Sn)
Encapsulation	Silicone Dioxide, Silica, Epoxy Resin, Phenol Resin, Magnesium Hydroxide, Carbon Black, and others

Resource: Diodes Incorporated – Part numbers AZ23C10 and 1N5711WS.

A diode is a semiconductor electronic component that allows the current to flow in one direction. Different elements in the structure of a diode consist of various materials.

Material Composition of Electronic Integrated Circuits (ICs) Components

You can find examples of materials in every element of an integrated circuit in this table:

Elements of an Integrated Circuit (IC)	Examples of Material Composition
Chip	Silicon
Insulator	Silicon Dioxide
Connector between different components	Aluminum
Mounting Package	Ceramic or Plastic materials
Wire leading from the chip to the mounting package	Aluminum or Gold
Impurities	N-type impurities such as Phosphorus and Arsenic P-type impurities such as Boron and Gallium

Resource: How Products are Made – Integrated Circuit

An Integrated Circuit (IC) consists of different electronic components such as resistors, transistors, and capacitors implanted onto a small chip of semiconducting material. Each element of Integrated Circuits contains various materials.

Classifications of Electronic Components

There are two types of electronic components:

Passive Electronic components
Active Electronic Components

What are Passive Electronic Components?

Passive electronic components do not need an external power source to operate. However, they can not provide energy on their own. They receive energy from active components and dissipate, absorb, or store it. The most common passive components are:

Resistors
Capacitors
Inductors

What are Active Electronic Components?

Active electronic components are fundamental components for the operation of any device. They require an external power source to supply and control energy in electronic circuits. Most active components contain semiconductors. The most common active components consisting of semiconductors are:

Transistors
Diodes
Integrated Circuits (ICs)

Material Composition and Regulated Hazardous Substances in Electronic Components

Some of the materials in electronic components contain hazardous substances like:

Heavy metals (e.g., lead, mercury, cadmium, etc.)
Brominated compounds (e.g., PBBs, PBDEs) and other Persistent Organic Pollutants (POP),
Phthalates (e.g., BBP, DBP, DEHP, DIBP) and other plastic flame retardants
Per- and polyfluoroalkyl substances (PFASs)

Environmental regulations worldwide tend to restrict the use of these substances of concern. Examples of these restrictions are:

RoHS on the Restriction of Hazardous Substances in electrical and electronic equipment
EU REACH with the Substances of Very High Concern (SVHC) and the SCIP notification
California Proposition 65 Chemical list
The US TSCA-PBT – Toxic Substances Control Act – addressing several Persistent, Bio-accumulative, and Toxic substances in articles

We are here to help you comply with these environmental obligations. Reach out to the Enviropass team for any questions regarding environmental compliance assessments of your electrical and electronic products.