If you're looking for the best material for your PCB, you're in the right place. In this guide, we will discuss all the different types of PCB laminate materials available today.
We'll discuss their pros and cons and help you decide which type of material for your project.
So, whether you're a beginner or an experienced engineer, read on to learn more about PCB laminates!
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What is Laminate in PCB?
Electronics industry concept: digital circuit board with microchips over the schematic diagram
Laminate is a material that PCB manufacturers use to fabricate printed circuit boards.
It is also made of thin layers of different materials, typically bonded with heat and pressure.
The most common type of laminate is FR-04, which is made of glass-reinforced epoxy.
And other types of laminate include FR-02 (polyimide), FR-06 (Teflon), and CEM-01 (ceramic).
The traditional four board layers are as follows: Substrate, Copper, Soldermask, and Silkscreen (from bottom to top).
Also, the laminates are developed by curing under pressure and temperatures of cloth using thermoset resin to create the final piece of uniform thickness.
Laminate plays a critical role in the performance of a PCB. For example, it affects the board's electrical properties, thermal conductivity, and mechanical strength.
Therefore, choosing the right type of laminate for your project is important.
Types of PCB Materials
Heap of PCBs isolated on white
The following are the main types of pcb laminate materials:
FR-4
FR- stands for Flame Retardant, a glass-reinforced epoxy laminate.
Plus, FR-4 is the most common type of pcb laminate material. Besides, it has good thermal conductivity and mechanical strength.
However, it is not suitable for high-temperature applications.
High-Performance FR-4
When working with multilayer PCBs, you should choose a high-performance FR-4 laminate.
The improved TG and decreased dielectric qualities make it more reliable and ideal for high-frequency circuits.
Copper Clad (CCL)
CCL, called copper-clad laminates, is a base material with a copper layer bonded to one or both sides. Plus, it is available in different thicknesses, with the thinnest being 0.0014”.
The reinforcing substance of the copper-clad laminate is glass fiber or wood pulp paper.
A CCL laminate is applicable for high-voltage circuits in most cases, such as in producing printed circuit boards (PCBs) or transformers' wiring.
The Teflon
Teflon is a fluoropolymer with excellent properties, such as a low dielectric constant and loss tangent. Teflon materials also resist chemicals, UV light, and high temperatures.
Manufacturing Teflon PCBs can be better as a dielectric material in capacitors and as heat-resistant insulation in high-frequency applications. It is also useful as a lubricant and for other non-stick applications.
Teflon materials are available in sheet form, and you can cut them into the desired shape with a CNC router.
High Tg Epoxy
It is ideal for multilayer PCBs. The material has excellent thermal and chemical resistance.
In applications where high humidity and extreme temperatures are present, Ultra High Tg Epoxy provides excellent electrical insulation. In addition, Tg EEPOXY is extremely adaptable, cost-effective, and flame-resistant.
Polyimide
Polyimide is a polymer with excellent heat resistance and electrical insulation properties. Also, extreme environmental stability is a characteristic of this type of laminate.
Polyimide is applicable on both rigid and flexible circuit boards with high-density, bendable, or inflexible circuits.
In addition, It also generates high levels of chemical, thermal, and mechanical properties.
Besides, Polyimide laminates are useful in a wide range of industries, including automotive, aerospace, military, and consumer electronics.
BT Epoxy
BT Epoxy has good heat resistance and electrical insulation properties. The BT Epoxy laminate is often useful on lead-free printed circuit boards.
Besides, it has excellent thermal, mechanical, and electrical properties. It is also resistant to chemicals and flame.
PCB Material Properties Consideration
Printed circuit board populated with some components
When choosing pcb laminate materials, you need to consider the properties important for your application. Some of the most important properties to consider include:
-Chemical Properties
*Moisture Absorption
Moisture absorption is the amount of water vapor a pcb material can absorb under specified conditions.
The moisture absorption rate is important because it affects the dimensional stability of the pcb material.
*Flammability
Flammability is the ability of a pcb material to catch fire and burn. In truth, the printed circuit board industry uses a classification system to rate the flammability of pcb materials.
The classifications are based on the pcb material's UL 94 Vertical Burn Test results.
*Methylene chloride resistance
Methylene chloride is a common solvent used in the pcb industry. It is important to know the methylene chloride resistance of a PCB material because it can attack and dissolve some PCB materials.
-Mechanical characteristics
High-tech electronic PCB (Printed circuit board) with processor and microchips.
*Density
The density of a PCB laminate material is important to consider because it affects the weight and thickness of the PCB.
*Time to Delamination
The time to delamination is when it takes for a pcb material to delaminate or fall apart. This is important to consider because it affects the strength and durability of the pcb.
*Peel Strength
The peel strength of a PCB laminate material is the force required to peel the material off the PCB. And this is important to consider because it affects the durability of the pcb.
*Flexural strength:
A pcb laminate material's flexural strength is the force required to bend the material. This helps to determine the PCB's ability to withstand forces without breaking.
-Thermal Properties
*Coefficient of Thermal Expansion (CTE):
The CTE of a pcb laminate material is the amount that the material expands or contracts when exposed to heat. This affects the thermal stability of the PCB, so it is important to consider this when choosing a PCB laminate material.
*Thermal Conductivity (k)
It is a measure of a pcb material's ability to conduct heat. Plus, the thermal conductivity of a PCB material is important because it affects the amount of heat that can be dissipated from the PCB.
*Decomposition Temperature (Td):
The decomposition temperature is when the pcb laminate material begins to break down. Also, the Td is important to consider because it affects the long-term reliability of the pcb.
*Glass Transition Temperature (Tg)
The glass transition temperature is when the pcb laminate material changes from rigid to rubbery. Plus, you can think of the Tg as the point at which the pcb laminate material becomes flexible.
-Electrical Properties
Electronic circuit board PCB with excellent electrical properties
*Dielectric Loss Tangent (Tan δ)
The dielectric loss tangent measures the pcb laminate material's ability to dissipate heat. Usually, different laminate materials have different dielectric loss tangents.
*Dielectric constant (Er)
It measures the pcb laminate material's ability to store energy. This is important to consider because it affects the electrical properties of the pcb. The dielectric materials with lower constants are better.
*Electrical Strength
The electrical strength of a pcb laminate material is a measure of its ability to withstand an electric field. Moreover, it is inversely proportional to the thickness of the pcb.
*Surface Resistivity (pS)
The surface resistivity of a pcb laminate material measures its ability to resist the flow of electrical current. Plus, it is also proportional to the PCB's thickness.
*Volume Resistivity (p)
The volume resistivity of a board material is a measure of its ability to resist the flow of electrical current. You can also calculate it by multiplying the PCB's surface resistivity by thickness.
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What to Consider When Selecting Printed Circuit Board Material
Now that you know the basics of the printed circuit board laminate material, here are some things to consider when selecting the right one for your project:
Cost:
Cost is always an important factor to consider when selecting any board material. You'll want to balance cost with the other factors on this list to find the best overall pcb material for your project.
Availability:
Some printed circuit board laminate materials are more easily available than others. This is something to keep in mind when making your selection, as it may impact your project's cost and lead time.
Performance:
Performance is key when it comes to the printed circuit board laminate material. When selecting, you'll want to consider factors such as thermal conductivities, dielectric constants, and more.
Lead Time:
Your pcb material's lead time can impact the overall timeline of your project. Be sure to factor this in when making your selection.
PCB Material Selection
SMD green multi-layer printed electronic circuit board with microcontroller and components
Now that you've learned about the most popular PCB materials, let's look at some of the alternative possibilities. Which one should you choose to assemble your PCBs among the aforementioned options? There are many things to think about. Here are a few examples:
Dielectric constant
One of the pcb materials' key characteristics is its dielectric constant. Plus, this value indicates how much a material can slow down electrical signals, and it's important for high-speed applications.
Thermal performance
Another pcb material consideration is its thermal performance. Will your application require soldering or other high-temperature processes? You'll need to ensure the pcb laminate materials you choose can withstand those temperatures.
Debugging electronics devices. PCB with microcontroller in electronics laboratory
Coefficient of thermal expansion (CTE)
The pcb laminate materials' CTE value is important because it indicates how much the material will expand or contract when exposed to heat. In addition, different pcb laminate materials have different CTE values, so choosing one compatible with your application is important.
Transition temperature
The transition temperature is the temperature at which the pcb laminate materials' properties change. For example, some pcb laminate materials become brittle at high temperatures, so it's important to know the transition temperature of your material.
Thermal conductivity
The thermal conductivity of a pcb laminate material indicates how well it conducts heat. This is important to consider because it can affect the overall performance of your device.
Electrical performance
The electrical performance of pcb laminate materials is important to consider because it can affect the overall performance of your device.
Flame retardancy
The flame retardance of pcb laminate materials is important to consider. Because pcb laminate materials are often used in devices that generate heat, it's important to know how well the material can withstand high temperatures.
Dimensional stability
This includes the thermal expansion coefficient and the water absorption of the pcb laminate material. Also, the dimensional stability of pcb laminate materials is important to consider because it can affect the overall performance of your device.
Higher glass transition temperatures (Tg)
This helps to improve the dimensional stability of pcb laminate materials.
Improved solderability
Considering if you will be soldering components onto your pcb is important.
High-Speed Networks Drive PCB Laminate and Material Choices
High-speed network equipment manufacturers require PCBs built using specific laminates that can survive the operating conditions, which include high frequencies and temperatures.
Therefore, they employ standard industrial procedures and strict internal processes to qualify PCB laminates for their products.
Different PCB stacks with the laminate layer as the core
Some of these materials include Tachyon and Tachyon-100G. Isola fronted these two laminates to build PCBs for high-speed digital applications like line cards and router backplanes.
These two materials have a loss tangent (Df) of 0.002 and a dielectric constant (Dk) of 3.02, which does not change up to 40 GHz.
The materials also feature spread glass and low-profile copper foil to reduce the weave-induced differential skew, minimize jitter, cut signal rise times, and reduce intersymbol interference.
However, Tachyon-100G has higher thermal stability with a low expansion coefficient on the Z-axis. Therefore, it is better for high-speed line cards (ethernet 100 Gbps) with multi-layer designs.
A Wi-Fi router’s PCB
But both materials can have a broad range of core and prepreg thicknesses, and you can process them using the same procedures as FR4.
All materials with similar properties can work as PCB laminates for high-speed network devices.
Printed Circuits Material Suppliers
Close-up a lead solder, a pin of an LED, and a transistor on a PCB board.
There are many printed circuit material suppliers that you can choose from. It is important to do your research to find a reputable supplier that offers good quality products.
Some of the most popular pcb laminate materials suppliers include:
- DuPont
- Rogers Corporation
- Taconic
- Isola
When choosing a pcb laminate material supplier, it is important to consider the quality of their products and their customer service and support.
It would be best to consider the lead time for delivery of pcb laminate materials, as this can impact your production schedule.
Once you have selected a pcb laminate material supplier, you must choose the specific material you want to use for your PCB.
Various pcb laminate materials are available on the market, and each has its unique set of properties.
PCB Laminate FAQ
What Is the Process of PCB Lamination?
Circuit board lamination involves placing the internal layers (prepregs and foils) under extreme pressure and temperature with a photosensitive dry resist in a vacuum heat press.
The PCB cures at high temperatures for some time, after which the material cools slowly, and pressure gets released gradually, resulting in a stack that forms a multi-layer PCB.
What Is the Difference Between Prepreg and Laminate PCB?
PCB laminates are the base or core materials that provide structural support to circuit boards and insulation between the copper foils or conductive layers. On the other hand, prepregs are insulation layers that can separate two cores (laminates) or a core and a copper layer.
PCB layers with the prepreg separating the core from the copper foil in the 4-layer stack and the laminate from the laminate in the 6-layer stack
What Causes PCB Delamination?
The root cause of delamination is trapped moisture between the layers. Improper storage of the base materials can make them absorb moisture, which will expand rapidly during lamination due to the high heat, causing delamination.
The separation can also occur during assembly because the soldering heat will expand the moisture, and the vapor must find a way out.
Can You Use Different Laminate Materials Within the Same PCB Design?
Yes, you can. However, you should consider the performance requirements for the different board sections to pick the most suitable core materials.
Summary
Abstract Central Computer Processors Concept. 3D illustration. Conceptual CPU on circuit board - PCB
In conclusion, PCB laminate materials are a key component in manufacturing printed circuit boards.
They provide rigidity and strength to the board and must meet specific requirements to ensure proper PCB functioning.
Many different types of PCB laminates are available on the market, so it is important to select the right one for your application. Thanks for reading!
Special Offer: $1 for 5 PCB Assemblies!
Please email [email protected] for details.