What are the Differences Between the CEM3 PCB and the FR4 PCB ?

Multilayer and double-sided printed circuit boards are usually used with a flame-retardant copper-clad epoxy glass board. The CEM3 PCB (printed circuit board) is a newly-developed substrate material that serves FR4-based printed circuit boards.

Before we go into details, let us know what a CEM3 PCB is.

What is CEM3 PCB?

This is a copper-clad composite laminate. It is composed of glass fiber cloth and copper foil that has been impregnated with epoxy resin (flame-retardant). The major difference between FR4 PCB and CEM3 PCB is that the CEM3 PCB is manufactured from glass mat and glass cloth composite substrate. It is not just glass cloth, it is also composite.

Furthermore, the board type is a layer of non-alkali electronic grade glass fabric that is non-woven. It is also impregnated with brominated flame-retardant epoxy resin. Each of these fabrics is an alkali-free electronic grade fiber cloth.

Also, the coating is with flame-retardant epoxy resin, adding copper foil on both or one of the sides. Also, the pressing is done hot into a laminate (copper-clad).


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How do you Manufacture CEMs (Composite Epoxy Materials)

You manufacture composite epoxy materials when you combine at least two materials that have different physical and chemical properties. You do this so as to get the right substrate material having unique characteristics and properties. Generally, CEMs are useful in printed circuit boards as a form of substrate material.

Furthermore, the printed circuit boards that make use of paper (cellulose) and glass fabric (woven) coupled with its substrate material as epoxy, are all referred to as CEM3 PCB boards. The material has a milky-white color and it is useful during the production of double-layer pcbs.

Also, CEM 3 possesses great mechanical and electrical properties. This shows that it has great tolerance for some mechanical processes such as punching and milling. Also, in contrast to FR4, the mechanical strength of CEM 3 is lower. However, as regards price, it is less expensive than the FR4.

Furthermore, the material possesses great endurance for solder heat and it works great with the lead-free soldering. Today, CEM 3 CBs are widely useful in fax machines, instrumentation, household appliances, telephones, and automotive electronics.

What is the Performance of the CEM 3 PCB?

All the following: the temperature of glass transition of the CEM PCB, the water absorption, peel strength, dip resistance, insulation resistance, UL index, electrical breakdown, etc – can meet the standard FR-4. The only difference is that compared to the FR4, the flexural strength of the CEM 3 is lower. Also, the thermal expansion of the CEM-3 is higher in contrast to that of FR4.

Furthermore, the processing of the metalized hole isn’t an issue for CEM 3 PCB. The wear bit of the drilling also goes on at a low rate. Also, punch forming and punching is easy. Asides from this, its accuracy for thickness dimension is also high. However the metalized hole’s inferiority is a bit poor.

Market Application of the CEM 3 PCB

UL feels that you can interchange the FR-4 and the CEM 3. Therefore double layer printed circuit boards using FR4 are readily available to serve as replacements. Since FR-4 and CEM 3 perform similarly, so also, replacing them on the multi-layer boards is now impossible.

CEM-3 made circuit boards are now useful in copiers, fax machines, home appliances, automotive electronics, telephones, and instrumentation.


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Further Development and Improvement of the CEM 3 Substrate

To adapt further to electronic products’ SMT assembly, the development of multifunctional, miniaturized, thin, and light CEM 3 substrates has seen more improvements. This has happened in these aspects.

Improvement of the resin system. With the use of resin, there’s an improvement in the Processability, reliability of the substrate’s hole metallization, and high-frequency properties.

There has also been an improvement in the glass non-woven mat and the glass fiber’s surface treatment, which is very important in improving the resistance of the insulation during any wet condition.

Also, the dimensional stability can see great improvements via the glass fiber ratio’s length.

With the CEM 3 substrate’s continuous improvement, as well as the performance’s improvement, the applications in our world today are now becoming much more popular.

Recently, adding to China, Taiwan, South Korea and Japan also deal in the production of the CEM 3. Furthermore, the development is very rapid too. The rate of growth is higher and higher in contrast to FR4.


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CEM3 PCB vs FR4 PCB: What is the Difference?

Recently, Japan has used lots of CEM3 rather than FR-4, which has even caused the CEM-3 to surpass the FR-4. A larger fraction (55%) of panels with two sides makes use of the CEM-3.

The process involved in the production of the CEM3 PCB is more like that of the FR-4. Also the glass mat gluing could be either a horizontal gluing or vertical gluing. This epoxy resin system which is used is similar to FR-4.

To achieve better performance, you can modify it. Most times, people add a particular amount of filter. Generally, the pressure for suppression is usually half lower compared to that of FR-4.

To meet requirements of the different thicknesses, you can use glass mats having different standard weights. The ones most commonly used are 105g, 75g, and 50g.

If CEM hopes to replace the FR-4, then it has to achieve the different properties that FR-4 possesses. All of the temperature of glass transition, water absorption, peeling strength, immersion resistance, UL indicators, insulation resistance, etc for the CEM 3 can meet the standard (FR-4). The only difference here is that the bending strength of the CEM3 PCB is low.

The metalized hole processing of the CEM 3 isn’t an issue. Press forming and punching is easy, and the dimension accuracy and thickness are high. However, the punching’s metalized appearance is a bit worse.

UL feels that FR-4 and CEM3 are interchangeable. Because CEM3 PCBs perform similarly to the FR4, this has made its substitution on multi-layer boards possible.


By now, you should be able to explain what the features of the CEM3 PCB are as well as the differences between CEM3 PCB and the FR4 PCB.

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