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PCB/PCBA knowledge
PCB Substrate - What Are The Types And What Materials Commonly Use

In this blog post, you’ll learn about all the details associated with PCB substrate. It’s one of the most important materials used in the PCB manufacturing process, which adds to the overall strength and foundation to the PCB chip.

Table of Contents

What’s a PCB substrate?

A PCB substrate is a kind of foundation or a base material, on which all the components are embedded. It gives strength and rigidness to the overall PCB and acts as a core of the entire PCB chip. Different layers such as copper plating and PCB layers are stuck to the PCB substrate using adhesive.

What are the types of PCB substrate?

Types of PCB substrate
Types of PCB substrate

1.FR4
FR stands for Flame Retardant, which discourages flames when the material is taken away from the fire. It’s made of glass fiber composite and epoxy resin, which makes it flame retardant.

Features
●Strong and durable material.
●Flame retardant.
●Cost effective.
●Long-lasting material.
●Easy to work on the machine.

Benefits
●It’s easy to manufacture and easily available in the market.
●Clients on a low budget can go for this material for a budget-friendly PCB.

2.PFTE
It’s short for Polytetrafluoroethylene, which is a synthetic compound. It’s one of the most preferred materials not only used as a PCB substrate, but also in the cookware industry.

Features
●Strong composite material.
●High-frequency material.
●High TG substrate.

Benefits
●It’s a perfect choice for high heat resistant PCBs.
●Heavy components or components that generate a lot of heat can be embedded on it without any worries.
●You can make a high component density PCB using this substrate.

3.Polyimide
It’s a soft substrate that offers incredible heat resistant, and is a perfect choice as a substrate in manufacturing PCBs.

Features
●Soft, yet durable and strong material.
●High heat resistance.
●High power substrate.
●Can resist UV and microwaves.

Benefits
●It’s a cost-effective substrate.
●It’s perfect for making soft and flexible PCB.

What are the properties of PCB substrate?

Properties of PCB substrate
Properties of PCB substrate

1.Thermal properties
The thermal property of a substrate defines how much heat can it withstand. The heat tolerance levels of a substrate define the heat tolerance level of the overall PCB. Moreover, thermal properties also define the levels of heat conduction in the PCB.

2.Electrical properties
Electrical properties of a substrate are the electrical conduction in the PCB. Electrical properties define the speed of signals traveling from one component to another. The bandwidth, signal transmission speed, etc., are all influenced and determined by the electrical properties of a PCB substrate.

3.Chemical properties
Any chemical composition of a PCB substrate falls under the category of chemical properties. This defines the chemicals and their constitution in the PCB substrate. The chemical composition defines the toughness of a PCB.

4.Mechanical properties
Corrosion, resistance to corrosion, hardness, plasticity, density, etc., of a PCB are defined using mechanical properties of a PCB substrate. The mechanical properties are highly influential when determining the right PCB substrate for your PCB, depending on it’s application.

What are materials commonly used in PCB substrates?

1.FR4
This is the most commonly used and highly preferred PCB substrate. It has a dielectric constant of 3, 8-4, 7 and has a temperature resistance of up to 135 degrees Celsius. Some more variants of an FR4 PCB substrate include:

a.FR4 halogen-free: it has a heat resistance of up to 140 degrees Celsius with a dielectric constant of 4, 5-4, 9.

b.FR4 high TG: This variant can withstand heat of up to 170 degrees Celsius.

2. RCC
With a dielectric constant of 4, 0, this is a type of foil, (electrolytic copper), which has a layer of coating of special epoxy resin. It can withstand heat up to 130 degrees Celsius.

3. Polyimide
This is a massive heat resistant material that can withstand heat up to 260 degrees Celsius. It’ a polyimide resin with a dielectric constant of 4, 4.

4. PTFE
If you’re looking for even higher heat resistant substrates, then this one has a heat resistance of 240 degrees Celsius to 280 degrees Celsius. This is a high frequency laminate, that is used in PCBs requiring stable dielectric constant.

Why is FR4 the most preferred PCB substrate material?

Why is FR4 the most favored PCB substrate material
Why is FR4 the most favored PCB substrate material

FR4 is a flame retardant substrate, which is a primary choice in PCB substrates. The reasons for its popularity are:

1.It’s a strong material, that lays a strong core and foundation to the overall PCB. Rigid PCB manufacturers, therefore, heavily rely on its strong mechanical properties for a durable PCB.

2.It offers a good insulation between the copper and other layers of the PCB, which help in neutralizing the chances and risk of any short circuit in the PCB.

3.There’s low magnetic and other type of interference in the PCB that’s made of FR4. As a result, the signal strength and transmission speed is high in PCBS that are made of FR4.

How to select a PCB substrate?

Selecting a PCB substrate requires checking and verifying the following things:

  • Usage and application
    Check your PCB requirement. Consider your PCB usage. Where will you use this PCB? If you need to use it in a networking device, go for FR4 PCB.
  • Consider ambience heat
    If you’re going to use the PCB in a hot ambient environment with a tight housing, such as mobile phones, etc., go for FR4 or polyimide substrates, that can handle high levels of heat without failing.
  • Thickness and rigidness
    Do you need a thick, thin, single-layer PCB or multilayer PCB? Do you need a rigid or a flexible PCB? Think of these questions before choosing a PCB substrate. For rigid PCBs, FR4 or FR5 is the most preferred choice. For flexible PCBs, go for polyimide substrate.

What are the factors that affect PCB substrate cost?

Factors impacting PCB substrate cost
Factors impacting PCB substrate cost
  • Material
    If you’re using polyimide, it’ll be costlier than FR4. Similarly, the choice of material of a PCB substrate will add or reduce your overall PCB manufacturing cost.
  • Supplier of your PCB substrate
    Different suppliers of PCB substrate have their prices. Buying from a well-known supplier may be a bit costlier than a less reputed or a new supplier in the market.
  • Supplier’s location
    If you’re buying from a distant supplier, the PCB substrate will be costlier due to transportation charges. If importing, be ready for import and custom duties as well.

Conclusion

After learning about PCB substrate, you might be wondering where to buy from. You don’t necessarily have to buy a PCB substrate separately. You can reach out to a PCB manufacturer, such as IBE Electronics and speak to them about your requirements. You can have a conversation to mutually finalize the best PCB substrate depending on your requirements. IBE Electronics will be helpful in such regards.

FAQ

1.FR4
2.RCC
3. Polyimide
4. PTFE

  • Usage and application
  • Consider ambience heat
  • Thickness and rigidness
  • Material
  • Supplier of your PCB substrate
  • Supplier’s location

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