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How to choose the right PCB material

PCB board life and performance depends on the choice of circuit board material. In order to select the correct board material, it is important to check the materials available for different board categories. There are different characteristics and physical characteristics that help to select the plate. When evaluating PCB materials, it is necessary to ensure that the design requirements meet the required circuit board performance.
When large amounts of current need to be handled, the spacing and width of the circuit board are also important. The structural strength of the board is determined by the substrate and laminate. The choice of materials for these two layers depends on the type of board.
Layers on the PCB and their significance
The PCB board is composed of four layers, namely substrate, laminate, solder mask and screen printing. The substrate and laminate together define the basic electrical, mechanical and thermal circuit board properties.
Substrate
Fiberglass FR4 is the most common material used for PCB substrates. Here, FR stands for flame retardant. Suitable for its rigidity and thickness. For flexible PCB, use Kapton or equivalent plastic.
The thickness of the PCB depends on its application or use. For example, the thickness of most Sparkfun products is 1.6mm, while the thickness of Arduino Pro products is 0.8mm. PCBs made of cheaper materials such as epoxy resin lack durability.
Substrates have been found in low-cost consumer electronics products. These have low thermal stability, which causes them to easily lose lamination. When the soldering iron is fixed on the board for a long time, the substrate will also cause smoke, which makes them easy to identify.

The non-conductive layer of the dielectric material is selected based on the dielectric constant.
The substrate must meet certain required properties, such as glass transition temperature (Tg). Tg is the point where heat causes the material to deform or soften. A variety of materials can be used for the substrate, such as aluminum or insulated metal substrate (IMS) FR-1 to FR-6, polytetrafluoroethylene (PTFE), CEM-1 to CEM-5, G-10 and G-11, RF-35, polyimide, alumina and flexible substrates such as Pyralux and Kapton.
“Overall, IMSes can minimize thermal resistance and conduct heat more efficiently. These substrates are mechanically stronger than the thick-film ceramic and direct-bonded copper structures commonly used in many applications.”


Post time: Apr-16-2020