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Fr-4 is a code name for the class of combustible materials, which means that the resin material must be able to extinguish itself after combustion state. It is not a material name, but a material class.
Classification of substrates
PCB substrates are mainly divided into four types according to different reinforcing materials:
FR-4: glass cloth substrate
FR-1, FR-2, etc. : paper substrate
CEM series: composite substrate
Special material substrate: ceramic, metal base
The origin of the name
FR - 4 is a kind of code of fire resistant material grade, represented by the mean resin material after combustion state must be able to put out a material specification, it is not a material name, but a kind of material material level, therefore the general FR - 4 grade materials used in the circuit board has a lot of kinds, but mostly four functions (Tera - Function) of epoxy resin and filler and glass fibre made of composite materials. Main technical features - stable electrical insulation performance, good flatness, smooth surface, no pits, thickness tolerance standard, suitable for application and high performance electronic insulation requirements of products.
FR - 4 definition (NEMA standard L | 1983) : refers to the test of glass fiber epoxy resin sample burning, its size is 5 inches long, 0.5 inches wide, the thickness of the informal without copper substrate, in particular the Bunsen burner, under the sample put 45 degrees of inclined try to burn it, then remove the fire and let already with flame retardant agent (e.g., 20% of the bromide) sheet of self extinguishing, and take the clock down from spread of the number of seconds after the fire, after ten times try to burn their total spread the number of seconds to less than 50 seconds to become V - 0, called V - 1 is less than 250 seconds, all accord with V - 1 sheet of glass fiber epoxy resin, are called FR - 4.
The applicability of plates
Advantages - low cost, low density, perforation processing
Disadvantages - low working temperature, poor heat resistance, poor moisture resistance, poor mechanical properties, poor hole metallization performance
Composite base PCB:
advantage - medium cost, medium density, impact machining or mechanical drilling
Disadvantages - low working temperature, general heat resistance, poor moisture resistance of CEM1, mechanical properties, limited hole metallization performance
Epoxy glass fiber cloth based printed board:
Advantages: high working temperature, good heat resistance, good moisture resistance, good hole metallization performance
Disadvantages: high cost, high density
Special base printed board:
Advantages: good heat dissipation, good mechanical properties, good electromagnetic shielding effect, good thermal expansion performance
Disadvantages: expensive, difficult to process
FR4 copper clad plate classification
A1 copper clad plate - mainly used in military, communications, computers, digital circuits, industrial instruments and meters, automotive circuits and other electronic products. This grade copper clad plate is widely used, all the technical performance indicators meet the requirements of the electronic products mentioned above, and the quality reaches the world-class level.
A2 copper clad plate, mainly used for ordinary computers, advanced household appliances and general electronic products. The performance indicators can meet the needs of general industrial electronic products, have a good price performance ratio, can make customers effectively improve competitiveness.
A3 copper clad plate, home appliance industry, computer peripheral, general electronic product development fr-4 products, its characteristics is the performance of the premise of meeting the requirements, the price has a competitive advantage.
Class B copper clad plate
Belongs to the secondary product plate, the performance may satisfy the request not the high electronic product demand, is suitable for the manufacture line spacing, the line width, the hole spacing and the aperture request not to be high ordinary single double panel