94V-0 Circuit Board - The Ultimate Guide in 2023
Fire is one of the many risks to consider in PCB manufacturing. Combustion can destroy a PCB and spread to other parts of the product, resulting in a complete failure. You also have to account for the fact that an overheated PCB can catch fire.
There are steps to mitigate this risk, including choosing a fire-resistant material for your circuit board. Find out more about the 94V-0 standard and the requirements PCBs have to meet to comply with this flame-retardant standard.
What Does 94V-0 Stand For?
The 94V-0 standard refers to a material’s ability to resist exposure to fire. This standard is the result of Underwriters Laboratories or UL coming up with their own flammability standard. You’ll sometimes find sources that refer to this standard as UL 94.
The letter V refers to the fact that the material must go through a vertical test. During this test, a flame burns the bottom of the material, and the testers track how far combustion progresses.
The number 0 refers to the acceptable degree of flammability. You’ll find other classifications, including V1 and V2, which correspond to a lesser degree of fire resistance.
What Does the 94V-0 Test Look Like?
Researchers apply two flames to a material to conduct the 94V-0 test. The material obtains the 94V-0 designation if it meets a few requirements:
- The material has to stop burning within 10 seconds after testers remove the open flame.
- The afterglow combustion doesn’t last more than 30 seconds.
- Researchers have to repeat this test on five samples. The total combustion time across these samples shouldn’t exceed 50 seconds.
- It’s acceptable that a portion of the sample burns, but the combustion shouldn’t go past the mounting clamp used to hold the sample in a vertical position.
- Testers place cotton underneath the burning sample to see if any burning particles drip from the material. The 94V-0 standard indicates that no material drips.
This comprehensive test ensures that the material will stop burning by itself once the exposure to a flame stops. It also guarantees that the burning material will not drip and spread the fire to other parts of the device. Testing five samples means that these results should be consistent.
The requirements for the V1 level are less strict and allow the material to burn longer:
- Combustion shouldn’t last longer than 30 seconds once the flame disappears.
- When testing five samples, the total combustion time shouldn’t exceed 250 seconds.
- Afterglow can last up to 60 seconds.
- The burn limit and dripping requirements remain the same.
The V2 level uses the same requirements as the V1 standard, but the burning material can drip melted particles and cause the cotton swab to catch fire.
Other Flammability Standards
The UL standard isn’t the only set of requirements guaranteeing a flame-retardant product. ISO and IEC have similar standards in place.
The 94V-0 standard shares requirements with the ISO 9772 and 9773 standards for plastics. There are a few differences between the 94V-0 standard and the IEC 60695-11-10 and IEC 60695-11-20 standards, but the requirements remain similar.
The UL and ISO standards are slightly stricter regarding how much of the sample can burn. These two tests set the limit at the four inches mark.
The IEC standard sets this limit at 125mm or 4.9,” which means the combustion can progress further into the vertical sample. The IEC standard also established guidelines for conducting a horizontal burning test on the samples, resulting in a more comprehensive testing process.
Everything About 94V-0 Circuit Boards
Circuit boards that meet the 94V-0 standards use quality materials with flame-retardant properties. These properties can vary depending on the materials used, but the 94V-0 standard establishes a clear requirement indicating a safe circuit board.
Flammability can vary from one PCB to another due to the materials used. There isn’t a single combination of materials that results in a circuit board compatible with the 94V-0 standard.
Instead, PCB manufacturers select different flame-retardant materials and put the PCB through a vertical burning test to see if the design is viable.
Most PCBs use copper for their conductive layer. Copper doesn’t burn, but other metals and alloys can catch fire.
PTFE or Teflon is a common laminate material. You’ll also find PCBs made from FR4 material, a glass-reinforced epoxy laminate material. FR4 uses woven fiberglass and an epoxy resin binder with flame-retardant properties. Some manufacturers add bromine to increase the PCB’s fire resistance.
You can also find G-10 PCBs, a fiberglass laminate that lacks the fire-resistant properties of PTFE and FR4.
The main downside of G-10 and FR4 is that these materials use epoxy resin. This polymer is flammable and potentially dangerous since it produces a lot of smoke when burning.
Manufacturers must modify the epoxy resin by introducing compounds like phosphaphenanthrene to reduce or prevent combustion. If you’re considering using FR4 for your PCBs, it’s crucial to look for a material that meets the 94V-0 standard.
Polyimide is another option for PCBs. This flexible polymer has excellent flame-retardant properties and can be more durable than FR4.
Single Side PCB
Most PCBs feature a single-sided design. These circuit boards have a conductive layer on one side, and the components sit on the other side with the soldering points.
Single-side circuit boards are simple and versatile. They allow for a lower density of components, facilitating assembly and preventing overheating. Plus, single-sided PCB tend to be cheaper to produce.
Even though a single-sided design can prevent overheating, you should still take steps to protect your prototype or product from fire and look for a 94V-0-compliant PCB material.
Double Side PCB
Double-sided PCBs feature circuit traces on both sides. These boards typically have drilled holes plated with a conductive material like copper to connect the two sides.
This design is ideal if you need to fit a lot of components in a tight space. Double-sided designs can facilitate things if you’re working on a complex project.
The double-sided PCB will usually have more routing traces, and the routing traces can sit closer. The higher concentration of components and routing traces can result in overheating, which is why opting for a PCB that meets the 94V-0 standard, or another flammability standard is crucial.
Why Do You Need a 94V-0 Circuit Board?
Did you know that electrical failures and malfunctions cause over 46,000 home fires each year? Old appliances and faulty outlets are the two main culprits, but electronics, machinery, and other products with PCBs can be just as dangerous.
Because fire is conductive, electronics and appliances can cause significant damage and result in injuries or even deaths when they burn.
Adopting the 94V-0 standard is one of the steps you can take to reduce risks and offer appliances, electronics, and other products your customers can feel safe about using.
You should adopt the 94V-0 standard because PCBs can overheat and combust. A crowded board will overheat faster, but events like short circuits or spark gaps can cause a board to overheat. Limited airflow, a lack of heat dissipation components, or a high external temperature can increase risks.
You also need to account for the fact that flames can come from an external source, such as a battery or another item that caught fire. With a 94V-0-compliant circuit board, the material will burn slowly and quickly stop burning once the fire is under control.
Plus, the burning circuit board will not drip and spread the fire to other components and can prevent more damage.
Awesome Properties of 94V-0 Circuit Boards
The 94V-0 standard focuses on measuring how easily and quickly a material burns. Properties can vary from one material to another since this test only measures a material’s flame-retardant capacities.
However, PCBs that meet the 94V-0 standards have a few properties in common:
- These circuit boards are flame retardant. When exposed to an open flame, they will burn slowly.
- Once the flame disappears, the PCB will stop burning within 10 seconds, and the afterglow shouldn’t last more than 30 seconds.
- The burning PCB will not drip and spread the fire to other components.
- These flame-retardant properties mean these PCBs can withstand high temperatures and might last longer, even in hot conditions.
- Meeting the 94V-0 standard allows for compact designs, including double-sided circuit boards.
- PCBs that meet the 94V-0 standard are compatible with ISO 9772 and 9773 standards. Most 94V-0-compliant products should also meet the IEC 60695-11-10 and IEC 60695-11-20 standards.
What Are the Most Compatible PCB Substrates With 94V-0?
When it comes to the circuit trace, copper is the most common choice for 94V-0 PCBs. This material doesn’t burn easily and is suitable for several applications.
Thanks to its high melting point and thermal degradation threshold, PTFE or Teflon can be a good option for meeting the 94V-0 requirements.
FR4 is another common option. This type of glass-reinforced epoxy laminate resists fire well, and it’s possible to modify this material by adding compounds with flame-resistance properties.
Polyimide is less common and tends to cost more, but this flexible material can meet 94v) standards. Compared to FR4, polyimide has better heat dissipation properties and can be a better choice if overheating is a concern.
The least common PCB material for applications requiring a 94V-0-compliant material is G-10. This polymer has a lower ignition threshold, but it’s possible to modify it by adding flame-retardant compounds to meet or exceed the 94V-0 standard.
Applications of 94V-0 Circuit Boards
There is a wide range of uses for 94V-0 PCBs. Even if your project doesn’t fit into these categories, adopting this standard will help make your product safer.
Prototypes
Prototypes typically go through rounds of testing. It’s crucial to choose a durable PCB material to prevent failures.
A sturdy circuit board that resists heat and fire well is a component you can easily reuse as you work on different iterations of your design.
Hobbyists and Students
Designing a circuit board from scratch can be challenging. As hobbyists and students go through the necessary learning curve, they might make mistakes with overcrowded designs that result in overheating. A 94V-0 PCB will help keep things safe.
Compact Devices
If you’re creating a compact product, you will likely have to use a double-sided PCB. Choosing a 94V-0 will keep the product safe, in case the circuit board overheats.
Consumer Products
From electronics to appliances, you can offer safe, reliable, and durable products by selecting flame-retardant materials. Choosing safe materials can reduce the risks of product liability claims.
Battery-Powered Electronics
Working with fire-resistant materials is crucial when designing products that run on battery power since a punctured or damaged battery can catch fire.
Industrial Settings
Industrial machinery goes through a lot of wear and tear, such as laser cutting machine or CNC machine. The Circuit board must use safe and reliable materials to run for hours at a time.
Cost of a 94V-0 Circuit Board
A 94V-0 circuit board is a cost-effective way to make your product or prototype safer. Many inexpensive options meet these requirements, including FR4 PCBs.
The manufacturer or supplier will have to include the cost of conducting 94V-0 testing in the product price, but the test is relatively inexpensive to implement.
Opting for a 94V-0-compliant material will not significantly increase the project’s price, and the added safety and durability justify any additional costs incurred.
Other factors, such as the size of the PCB run, the number of layers, or any manual assembly steps, will more significantly impact the price of your project.
Reference: How Much Does a PCB Cost?
Conclusion
The 94V-0 standard indicates that a PCB has passed a test that guarantees the product is flame retardant. It doesn’t make the material flameproof, but the circuit board will burn slowly, and combustion will stop quickly once the flame disappears. You also won’t have to worry about the material melting and dripping.
Adopting this standard won’t increase your production cost, but it will make your product or prototype much safer. It’s a crucial requirement for industry and heavy-duty applications. Still, it’s also an intelligent decision if you want to offer a high-quality product or prevent failure when putting a prototype through testing.
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