PCBs are a mainstay of the modern world.
Found in everything from simple electronics to space age hardware, this is one piece of technology that abounds everywhere.
When it comes to their manufacture, there is a lot that goes into their construction.
From the raw materials used, to the actual manufacturing process itself, there is a lot that goes into the preparation of modern PCBs.
As for the materials that are used, they are indeed many.
Although many of the basics about the PCB design, such as the substrate, circuitry components and other additions are fairly identical, there are many variations as well.
These variations in turn, largely exist for the purpose certain specific properties that the materials have, in need by the PCB user.
To start off, it is important to get a rough idea of what the two materials actually are.
FR-4 is a material used as a flame retardant in electronics such as PCBs among others, which in turn, is comprised of woven fiberglass cloth, with a flame-resistant epoxy resin binder. FR in turn, is an acronym for ?Flame Retardant?, and is an indication that it adheres to industry standards, which in this case, has a standard code of UL94V-0.
Rogers in turn, is a reference to the Rogers Company, which manufactures laminate materials used in design of circuit boards. The materials are comprised of FR4 compliant materials, which are glass fiber and epoxy composites, with copper-foil laminates on either or both of the sides. The laminates in turn, are known for cores that have better high-frequency properties, and designed using materials such as Teflon.
Long story short, the two materials are both commonly used in the PCB industry, when it comes to flame-resistant boards, with Rogers being more attuned for high-frequency applications.
As far as the difference between the two is concerned, there are a few of them, which are worth mentioning.
One of the key differences between the two happens to be the price.
There is a sharp price difference between the two materials, with one being more expensive than the other.
In general, FR-4 is considered to be the cheaper of the two materials, while Rogers?s material is the more expensive one.
For those having PCBs designed on a budget, going for FR-4 would be the most ideal choice, while Rogers is preferred for those who prefer quality over cost.
2.) High Frequencies
As already mentioned, one of the key differences between the boards, is not so much in the construction and design, although some variations do exist.
The real difference has to do with the applications that the boards are used for varying frequencies, with Rogers materials used in applications which have higher frequencies.
FR-4 materials on the other hand, are more broad-ranged in application, and can be used for a variety of frequencies, as opposed to a select few ones.
3.) Impedance Stability
Impedance is the obstruction or the measure of obstruction of an electric current, towards the energy flow that takes place whenever a certain voltage is applied.
FR-4 materials tend to be highly susceptible to variations in the dielectric constant, while Rogers doesn?t have the same problem.
This means that in cases where one has to design PCBs working with broad temperature changes and little variations, high-frequency laminates such as Rogers would be an ideal choice. FR-4 materials on the other hand, can be used for everything else.
4.) Space Applications
An increasingly important industry of the modern era, space exploration is one of the newest frontiers in PCB use.
When it comes to space technology, PCBs have found widespread use, in everything from satellites to probes and everything in between. While both FR-4 and Rogers can be of use, Rogers is typically a more preferred option.
One of the main reasons, has to do with a phenomena known as ?outgassing?, where the gases trapped in the board during the manufacturing process is released. Then other issues emerge, such as the penetration of moisture or corrosive materials into the board and damaging it.
At the same time however, it should be added that in terms of absolute performance, FR-4 is a more suitable choice, given that it delivers better results in comparison, although it isn?t a suitable choice given its ?outgassing? issues.
The Dissipation Factor or DF also plays a major role in the selction of FR-4 or Rogers material.
Dissipation factor can be thought of as the loss of energy that takes place in a capacitor or other circuitry, whenever a current is applied.
FR-4 materials have a high dissipation factor, in comparison to Rogers materials, when used at high-frequencies. This makes Rogers a suitable choice for applications where high-frequency requirements are a necessity.
But in general, the dissipation factor is low in general applications, which make FR-4 an ideal choice for standard applications, in comparison to Rogers.
6.) Dielectric Constant
The dielectric constant can be thought of as the ability of a substance to store electrical energy across an electric field. This is something of prime importance, when it come s to the manufacture of PCBs.
In general, FR-4 materials have a dielectric constant of about 4.5, while that of Rogers is about 6.15 to 11.
For applications where the storage of electricity is of importance, while those without, is where Rogers is more suitable.
One limitation here is that the PCBs with high dielectric constants tend to break down faster, especially when subjected to intense electric fields.
7.) Temperature Management
The issue of temperature is especially important, given that the primary purpose of both the boards is to ensure that they don?t catch fire when being used.
In this regard, it is important to take into consideration the temperature management aspect of the boards, which in simple words is the ability of the materials to maintain a stable temperature over an extended period of time while in use.
In cases where the board has to work with little variation over a high temperature range, the ones made from Rogers materials are of an ideal choice. In those where the opposite is true, the FR-4 materials are a more suitable material work with.
To sum up, these are some of the key differences, between the two materials used by the PCB industry.
There are indeed others as well, with the above mentioned being one of the main ones.