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How to choose PCB base material?

From:pcb assembly Read:Time:2017-11-19 21:49
Printed circuit board base material basically has two types: organic substrate materials and inorganic substrate material. The most often used is organic substrate material.
 
Different layers PCB also use different base material such as 3 ~ 4 layer board with prefabricated composite material, double panel for the most part to use glass - epoxy resin material. Utilizing electronics assembly process, a greater degree of printed circuit boards bends when heated due to temperature increase, therefore, in the SMT requirement as far as possible use small bending degree of plank, types of substrates such as FR – 4 base material. Because of substrate after heat stress on the impact of component which will cause the electrode and reduce the reliability, when select base material should also pay attention to material expansion coefficient, especially when the component is greater than 3.2 x 3.2 mm.
Surface mount technology requires PCB base material with high thermal conductivity, excellent heat resistance (150 ℃, 60 min) and weldability (260 ℃, 10 s), high (more than 1.5 x 104 pa) copper foil adhesive strength and bending strength (25 x 104 pa), high conductivity and dielectric constant, good cutting precision (+ / - 0.02 mm) and the compatibility with cleaner, additional requirements appearance smooth level off, not warp, crack, scars and rusty spot, etc.
Printed circuit board base material normal thickness is 0.5 mm, 0.7 mm and 0.8 mm, 1 mm and 1.5 mm, 1.6 mm (1.8 mm), 2.7 mm (3.0 mm), 3.2 mm, 4.0 mm and 6.4 mm.  0.7 mm and 1.5 mm thickness of the PCB is used in the design of double panel with gold finger, 1.8 mm and 3.0 mm for non-standard sizes.Printed circuit board size in terms of production, minimum veneer should not be less than 250 x 200 mm, generally the ideal size for (250 ~ 350 mm) x (200 x 250 mm), for the long side is less than 125 mm or edge is less than 100 mm wide PCB, easy to use makeup.
 

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