Single Sided PCB
SIMPLE AND SMART !
The printed circuit boards (PCBs) have been a massive step in the history of electronics. Simple and smart, the concept of the single-sided PCB is still the same as a long time ago, but it benefits from the latest innovations in production processes and materials. New technology is always expensive as can be easily explained by the increasing costs of development, production, new machinery and patented processes. With time, those technologies become more accessible which makes the single side PCB more advanced, but also more affordable.
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PCB : WHAT ARE THEY MADE OF ?
A single layer Printed Circuit Board is made of insulating material, known as the substrate. Most of the time, this material is glass fibre reinforced (fibreglass) epoxy resin or phenol resin on which a copper layer is laminated in the desired pattern. The copper circuits are coated with a layer of tin-lead to prevent oxidation and assist the soldering process. Other finishes are also available, such as OSP (Organic Solderability Preservative) or chemical gold. Contact fingers are plated with nickel, and finally electrolytic gold (0.025 to 2µm) for excellent conductivity. Different options are possible such as silver-cross or carbon connections, carbon contacts, and different types of solder mask which can be either silkscreen or a photo-imageable process.
Those materials are used in every-day devices that don’t require a large amount of modern technology. They are made of paper and phenol which are cheap and easy to build, but with poor resistance to heat (130°). The FR1 is still available on the market but is gradually being replaced by CEM1/FR3 and FR4 materials.
CEM-1 is a composite material composed of woven glass fabric and a paper core combined with epoxy resin. With properties of easy punching, excellent electrical properties, and higher flexible strength, the CEM-1 provides excellent mechanical and electrical properties and punches well up to 2.36 mm (0.093″). The CEM-3 is very similar to FR4 but, instead of woven glass fabric, a ‘flies’ type is used. CEM-3 has a milky white colour and is very smooth. It is a complete replacement for FR4 and has a very large market share in Asia. It is a type of flame-retardant epoxy, copper-clad, plate glass material, and is generally used in electronics for double sided-PCB boards
FR is for “Flame Retardant”. As a printed circuit board is made to work with electricity, it is supposed to resist heat. FR4 has a much better heat resistance than FR1/XPC thanks to a different composition of its layers. The FR4 PCB core is made of fibreglass epoxy laminate. It is the most commonly used PCB material at 1.60 mm (0.062inch) thick. The FR4 uses eight layers of glass fiber material as a standard. The maximum ambient temperature is between 120° and 130°C, depending on the brand and filler. FR1 is the cheapest option you can find but nowadays, FR4 is affordable. FR4 is the best selection in the market to make PCBs. Some materials may be cheaper but they can only be used to make one-layer boards, and the reliability of the boards made by these materials is not good. Therefore, they are only used for single-layer and very simple boards.