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What is glass epoxy pcb board?
There are two elements of this term that you need to understand, which are: epoxy resin and printed circuit board
Epoxy resin is the raw material of copper clad laminate. Printed circuit boards use conductive wires to make electronic connections active
Epoxy PCB is then defined as a PCB made using epoxy resin.
There are many types of epoxy materials, so there are many types of this PCB
What is epoxy in circuit boards?
The main component of copper clad laminate on PCB is epoxy resin material.
This material is used to make the circuit board conductive
Epoxy materials, whether fiberglass-based or paper-based, need to be laminated.
During the lamination process, the epoxy resin itself melts into the cladding.
The choice of epoxy resin depends on the PCB designer.
But in doing so, the designer must weigh the price range with the characteristics of the epoxy resin material.
The purpose of using epoxy resin on PCB
The main answer is that epoxy resin is a form or protection. Another way to say it is that epoxy resin is a form of insulation on the circuit board.
But what to protect? When epoxy is weak or misapplied, the following can damage the PCB:
Overheating - can happen when the end device is in a hot environment. Vibration - when the end device is inside a gadget with engine problems
Shock - like when the end device is dropped. Temperature changes - such as changeable weather
What are the types of epoxy PCBs?
The type of epoxy material determines what type of epoxy PCB it is. Due to the wide range of customers, there are many options for epoxy materials:
Glass fiber reinforced (i.e. FR4 or FR5)
Paper-based epoxy
Compound epoxy, such as CEM-1 or CEM-3
High Tg, high CTI epoxy
Lead-free options, such as ceramic variants
Even with the wide range of choices, there is no doubt that FR4 material will prevail.
This is because it is flame retardant and strong due to its reinforced glass fiber content. It is also the most cost-effective.
What substrate materials can be used when making glass epoxy PCB boards?
The substrate materials used to make epoxy PCBs are divided into four different categories.
These include:
Rigid or Hard Substrate
If the main purpose is to ensure that the epoxy PCB retains its shape over time, a ceramic-based or rigid material will be required.
Due to the sturdy nature of these materials, the epoxy PCB will not deform, thus maintaining its shape throughout its lifecycle.
When building a computer motherboard, you will use a rigid material to make the epoxy PCB.
Rigid materials that can be used when making epoxy PCBs include beryllium oxide or aluminum nitride.
Some of the advantages of using these hard substrate materials include:
1. They continue to function even at temperatures exceeding 350 °C.
2. In addition, they also have a high dielectric constant.
3. Since they absorb minimal moisture, they facilitate sealed packaging.
4. In addition, they do not experience any outgassing issues.
5. They allow for packaging in small configurations and mate well with other PCB components.
Some of the reasons why a hard substrate is needed to make an epoxy PCB include:
1. Situations where you need a clear signal path.
2. When you need to reduce the price during mass production.
3. In areas where the application requires a sturdy printed circuit board.
4. When you need to conduct quick maintenance and repair practices.
Flexible or soft substrates
When you use flexible substrates, you can use them in various applications because they can be folded or bent into many shapes.
Therefore, many modern consumer electronics use these substrate materials in epoxy PCBs.
Also, you will use flexible substrates in epoxy PCBs when the application requires it to be bent frequently during operation.
Flexible substrates allow this to happen without affecting the flow of current.
Examples of industries that use this substrate include smartphones, wearable devices, etc.
The material that will be used when manufacturing flexible epoxy PCBs is called Kapton.
Also, the material has suitable heat resistance, consistent dimensions, and has a suitable dielectric constant value.
The most popular flexible epoxy PCB material substrates are polytetrafluoroethylene and polyimide.
Some of the advantages of using flexible epoxy PCB materials include:
1. They take up less space, thus enhancing the portability of the application
2. They are lightweight, thus suitable for small applications
3. They are suitable for making epoxy PCBs that will experience tuff environments
4. Also, due to their small size, they can be properly adapted to high signal traces and density uses
5. Flexible epoxy PCBs will provide proper stability as they form a coating close to the filler.
Some of the situations where you need to use flexible epoxy PCB materials include:
1. When the epoxy PCB is designed for use in extreme conditions
2. In applications where the epoxy PCB needs to bend or flex
3. When you need a lightweight and small epoxy PCB
Rigid-Flexible Substrate Materials
These epoxy PCBs use both rigid and flexible materials.
In addition, they contain multiple layers, formed of polyimide materials.
Some of the advantages of rigid-flex epoxy PCBs include:
1. Easy processing
2. They have low dielectric loss levels
3. Also, they are lightweight and take up less space
4. They are built with precision
Fields where rigid-flex epoxy PCBs are needed include:
1. When making power amplifiers and receivers
2. In cases where lightweight epoxy PCBs are required
3. When tags related to frequency identification are included
4. Military and medical application boards
5. Building automotive sensors and radar systems
RF-4 Substrates
These are glass fiber epoxy materials that are relatively cheap, have moderate fire resistance, and are good electrical insulation.
FR stands for flame retardant, meaning that they will meet UL94VO certification.
Their flame retardant properties are because they contain bromine halogens.
Advantages of FR-4 epoxy PCB materials include:
1. They are affordable and adaptable
2. In addition, their construction includes prepreg sheets containing epoxy resin and glass fiber mats
3. They are easy to drill and metallize according to electronic industry standards
Instances where FR-4 epoxy PCBs are needed include:
1. During prototyping
2. When manufacturing complex designs that require multiple layers
3. In scenarios where production costs need to be reduced
4. Applications that require low-speed circuits
Are epoxy PCBs strong?
Glass Epoxy PCB boards are strong, but this depends on the strength of the variety of epoxy you use.
Some of the main strength characteristics include:
Compressive strength
Peel strength
Shear strength
Flexural strength
The epoxy adhesives you will use on epoxy PCBs present high levels of strength.
In addition, some heat-curing epoxy adhesives have strength values between 35 N/mm2 to 41 N/mm2.
Should epoxy PCBs meet a set of international quality standards?
Yes, epoxy PCBs must meet these quality standards as it ensures that they are safe to use and meet the set requirements.
Some of the quality standards that glass epoxy pcb boards should adhere to include:
UL Certification
Restriction of Hazardous Substances [RoHS]
SGS Certification
ISO 9001 and 14000 Certification
What surface finishes can be used when making epoxy PCBs?
The purpose of the PCB surface finish you will use on epoxy PCBs is to protect the components on the PCB from oxidation or short circuits.
In addition, the surface finish forms a suitable connection between the epoxy PCB components and the PCB itself.
Some of the surface finishes you can use on epoxy PCB boards include:
Organic Solderability Preservative [OSP]
Immersion Silver
Electroless Nickel Immersion Gold [ENIG]
Gold or Nickel Electrolytic
Lead-Free Hot Air Solder Leveling [HASL]
Immersion Tin or White Tin
Electroless Nickel Electroless Palladium Immersion Gold [ENEPIG]
What is the Future of Glass Epoxy PCB Boards?
More research is being conducted on enhancing the substrates that will be used when manufacturing epoxy PCBs.
The need to manufacture lightweight and small epoxy PCBs has increased the demand for high-performance and functional multilayer PCB manufacturing.
In addition, there are new epoxy materials such as FR-408, Megatron, Getek, 4000-13, etc.
These materials have driven the advancement of PCBs because they have better performance compared to FR-4 materials.
RoHS regulations require the use of materials with higher heat resistance and reliability.