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Multilayer PCB consist of 3 or more circuit layers bonded together by a thickness of insulating material called prepreg and core. Multilayer printed circuit boards are most complicated than others, and are generally considered to be the most sophisticated PCB product due to their construction methods and design complexities.
These are a few of the applications using multilayer printed circuit boards:
Communications
Industrial controls
GPS technology
Aerospace
Computers
Military
Medical
Satellite systems
General specification for Multi-layer printed circuit board
1, 4-38 layers
2, Board finished thickness: 0.3mm-7.0mm
3, Material: FR-4, CEM-1, CEM-3, High TG, FR4 halogen Free, Rogers, Telfon.
4, Max. Finished board size: 23*25(580*900mm)
5, Min. Drilled hole size: 6mil(0.15mm)
6, Min. Line width: 3mil(0.075mm), Min. Line spacing: 3mil(0.075mm)
7, Surface finish/treatment: HASL/HASL lead free, Chemical tin, ENIG,Immersion Silver, OSP, etc.
8, Copper thickness: 0.5-20 oz
9, Solder mask color: Green/yellow/black/white/red/blue
10, Copper thickness in hole: >25.0 um(>1mil)