PCB Insulation Guide

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Nov 18, 2019|Product Innovations and Design, Technological Advancements and Materials

A PCB, or printed circuit board, generates heat as electricity flows through it. Without proper insulation, this heat can create massive problems for you and your PCB. Don’t wait until it’s too late, read on to discover more about PCB insulation.

Why Insulate a PCB?

Before understanding PCB insulation, we must answer the question, “What is a PCB?” 

A PCB, or printed circuit board, is a small green square with copper pieces. You can find one in nearly every electronic device in your home! A printed circuit board allows electronics to function correctly, making them a vital yet typically unseen part of our daily lives. Without them, our computers, phones, televisions, and electronic gadgets would work, or would not exist.

Electricity is vital to a PCB’s function. PCBs contain printed copper wiring, and so they naturally conduct electricity. However, electrical components can be hazardous if they are not enclosed in a non-conductive case, or if they become too hot. It is essential to insulate a PCB to prevent corrosion of the copper elements and to reduce accidental contact with conductive materials. Proper insulation can help keep a PCB from overheating or bursting into flames. 

There is more than one way to insulate a PCB. There are several common insulation materials, but the exact type of insulation often depends on the application the PCB was designed for.

PCB Insulation Materials

Common PCB insulation materials are often formed into non-conductive substrates, which meld together in several layers to allow electrical currents to travel correctly throughout the board. Simpler PCBs may be single-sided or single-layered. Complex PCBs, such as those used in high-speed digital communication, may be comprised of over twenty layers.

A PCB insulation calculator can help you determine creepage distances and clearance, which will factor into the exact type and quantity of insulation materials you may need. Creepage distance is the shortest distance between conductive parts, and clearance refers to elements separated by air, not substrate. Understanding creepage distance and clearance is essential for calculating PCB insulation. 

A PCB manufacturing company can choose to insulate with many different materials, ranging from the inexpensive plastic-like FR-2, to robust and sturdy metals such as aluminum. The intended use of a PCB often determines the materials used to insulate it. For example, the PCB in a cheaply made electronic toy will not require the same kind of insulation as the PCB in a satellite. 

To better understand PCB insulation and insulation materials, let’s explore the five most common forms of PCB insulation materials.

FR-2

FR-2 is a low-grade, flame-resistant laminate substrate option. It is a composite material created from paper and plasticized phenol resin, making it both lightweight and durable. Single-sided circuit boards often employ this material. FR-2 is halogen-free, non-hydrophobic, and can be punched or milled easily. One of the least expensive choices of PCB insulation, FR-2 is a common choice for companies producing single-use consumer electronics. 

FR-4

FR-4 is a high-grade, flame-resistant laminate substrate option. It is a composite material created from woven fiberglass, and it is often used in the manufacture of double-sided and multilayer PCBs. FR-4 can withstand higher temperatures and physical pressure than FR-2. It is also an affordable material, making it a popular choice for manufacturers of high-end consumer electronics. FR-4 is not as quickly mechanically processed and requires tungsten carbide tools to be milled, punched, or machined. 

RF

RF substrates are designed to allow PCBs to function within applications that use high-powered radio frequencies and microwaves. RF substrates are most often used on PCBs installed in military electronics, aeronautical electronics, and aerospace electronics. Though, it is important to note that there are a few consumer electronics that contain this type of substrate. The plastics that comprise a typical RF substrate do not create a tremendous amount of insulation, though they do perform well when tasked with generating strong electrical currents. RF and microwave PCBs typically have very few layers, sometimes only one or two. 

FLEX

Though most printed circuit boards are flat and rigid, there are innovative PCBs that are capable of flexing in nearly any direction without breaking. Flex circuits require a similar but unique form of insulation. A PCB insulation spray is often used to protect flex circuits, though plastic film is also a popular option. Flex circuits require a thin but sturdy PCB insulation coating that will allow them to move freely and fit into tight, restricted spaces. 

METAL

It may seem strange to choose metal as an insulator. Metals are typically conductive, and accidental conductivity can cause your PCB to malfunction, misfire, or melt. However, in certain instances, it may be more beneficial for a PCB to have a metal substrate. Metal is an excellent thermal conductor, allowing it to handle immensely powerful electrical currents without breaking or burning. PCBs installed in powered devices that consume a large amount of electricity may need a metal substrate to function efficiently and effectively. 

Candor Industries Can Help

To keep your PCB safe from overheating, sparking, or catching fire, it must be adequately insulated. The variety of insulation materials corresponds to the type of uses a PCB offers.

General electronics PCBs may work best with a simpler, more cost-effective FR-2 or FR-4 substrate. However, an RF substrate is better suited to applications involving high-powered radio frequencies. Flexible substrates such as plastic are ideally suited to meet the insulation needs of flexible circuit boards. And a metal can keep powered electronics cool while maintaining excellent thermal conductivity. 

A reputable PCB manufacturing company may be able to answer any questions that you have concerning PCB insulation. 

Candor Industries can provide you with a quote regarding your PCB needs, no matter how big or small. Our team of experienced professionals is eager to help. Our products include RF PCBs, Aluminum PCBs, Flexible PCBs, and much more. Our research and development, service, and innovative process differentiate us from competitors, and our sales and engineering team always welcomes inquiries.

Contact Candor today to learn more and receive a quote.