What Are Printed Circuit Board Made Of
Fri, Nov 08, 2019
Printed circuit boards are a standard feature of technology today.
Found in just about every single piece of electronic gizmo that one comes across, this is one piece of technology that has a universal nature unlike anything else.
As much as they have become ‘common place’, there is a certain ‘curiosity’ about them which many people have.
It is not so much about the way they function, but rather what they are made of.
There is a good reason for this. Printed circuit boards are unlike anything in the world, when it comes to electronics. With their distinct shapes, designs and coloration, it is probably the first thing that would catch the eye of anyone disassembling a piece of electronic.
This curiosity is certainly understandable.
Given that humans are a ‘curious’ species by nature, it is only to be expected.
With regard to the actual components of a printed circuit board, it would be interesting to note that the technology has been fairly ‘standardized’. In other words, its construction in standard industry practices is to a large extent the same all over the world, in terms of material, design, techniques and other related aspects.
When it comes to the construction of printed circuit boards, it can be said the the technology has undergone a tremendous amount of evolution to reach the present form.
Over the years, many practices have become common place, along with the usage of several different materials that are used in the construction of your average printed circuit board.
Details of the same are given in the points below.
1.) The Main Board
The main board forms the backbone of the modern PCB design.
It is the foundation on which all of the other circuits are placed.
There are many different materials that have found them being used for the main board’s construction. These included everything from plastics and wood to other materials.
As time progressed, it was decided that the material of choice was standardized in favor of resins. Today, there are a wide range of resins used by the industry, the two most common being that of ‘fiberglass’ epoxy and the ‘paper reinforced phenolic’ resin.
The latter is the cheaper one to manufacture, which makes it very useful for commercial electronics. The former on the other hand, is relatively expensive but tends to be more stable, which is why it is used in general for heavy duty applications.
2.) The Circuitry
The Board is one part of the equation.
What makes the printed circuit board a ‘circuit’ at the end of the day are the many circuits that exist on its surface, in one form or another.
The standard industry practice for the creation of circuits is the use of copper foil, which is bonded to the surface of the boards. This holds true for both kinds of boards, i.e. whether the same is made using fiberglass epoxy resin or that of paper reinforced phenolic resin.
The way that the circuitry is added to the surface will depend on the industry, and the purpose that the board is used for. There are currently two ways in which the circuitry is added; plating and etching.
The term ‘plating’ refers to the ‘deposition’ process in which a thin layer of metal is deposited on the surface along a predetermined path, decided in advance during the design stage.
The second process of etching is one in which a metal path is etched with the help of suitable tools, thereby creating the circuit required.
It should be added that the metal of choice is not always copper, although it has become an industry standard. Depending on the need and requirement, other metals or alloys may be used as well. In many cases, such as that of fine electronics and smart phones, the metal of choice is not copper but rather silver or gold. In fact, in a lot of these modern electronic gadgets, there is actually more gold per ton of the finished product, than there is gold in gold ore.
3.) The Protective Layer
The next important component of printed circuit boards is a protective layer, typically made from either a metal or metal alloy.
The practice became standard in the industry in an effort to prevent the oxidation of the circuitry. This was especially important in the case of printed circuit boards, as they were essentially exposed metal surfaces as opposed to metal wires, which had an insulating layer which doubled up as a form of protection against corrosion.
There are many different materials used for this protective layer. In general, the most common material of choice is zinc, as it is both affordable as well as offers a high degree of resistance against corrosion. In other cases, alloys are used, typically those of tin and lead. The exact material of choice will vary based on industry and application requirements.
These days, there has been a trend to add another layer of protection on top of the protective one, which is that of water-proofing materials, often consisting of polymers. Although this is not yet standard practice, they have become rather common in the manufacture of devices such as smart phones in an effort to make them ‘water resistant’ or ‘water proof’.
4.) Other Additions & Components
In addition to the above, there are other additions and components that are used in printed circuit boards.
These are not always a given, with certain exceptions. They are usually very application specific, meaning that the exact nature of the component, as well as the ways in which it is used, will vary.
There are several different components that come under this category. Some of the most common ones here include, but are not limited to, resistors, diodes, capacitors, transistors, integrated circuit chips and so on.
Also to add is that these components are often used in ‘combination’ with each other, meaning that you can usually find several of them together.
To sum up, the modern printed circuit board employs the use of a wide range of materials, along with others which may be proprietary trade secrets.
But as a whole, the materials used in their construction are fairly standard, and have been for a very long time.
And until a revolutionary new material or set of materials come about, vastly superior to the ones used today, it can be expected that this will not change in any way.