The layer count of PCB determines its manufacturing technology difficulty and PCB manufacturing cost. PCB boards can be briefly classified into two categories: single-layer (single-sided) PCB and double-layer (double-sided) PCB. When it comes to high-end electronic products, a couple of signal layers can be added to the inside of PCB apart from surface routing due to some limitations in terms of board real estate and board design. During the manufacturing procedure, after routing for each layer has been finished with positioning and lamination completed, multiple layers of signals will be pressed into a single board that is called multilayer PCB. Therefore, a multilayer PCB refers to any piece of circuit board containing more than two layers of signals. Multilayer PCBs can be multilayer rigid PCB, multilayer flex PCB and flex-rigid multilayer PCB.
Necessity of Multilayer PCB
Due to the increasing use of IC (Integrated Circuit) package, interconnection lines become so dense that multi-substrate boards become necessary. In addition, some design problems, like noise, stray capacitance, crosstalk etc., are so protruding that should be solved through multilayer resolution. As a result, multilayer PCB design has to make sure that signal lines should be minimized and parallel circuits should be avoided, which is apparently difficult to be obtained in either single-sided or double-sided design. Therefore, multilayer printed circuit boards come into being for the acquisition of perfect performance of circuits.
The original aim of multilayer PCB is to provide more freedom in terms of routing for circuits that are complex and/or sensitive to noise. There are at least three layers in a multi layer circuit board and two layers are external with the left layer(s) synthesized inside insulating plate. The electrical connection in a multilayer PCB derives from plated through hole on the cross section of circuit board.
Advantages of Multilayer PCB
• Smaller size
• Lower weight
• Higher speed of signal transmission
• Constantly low impedance
• Better shielding effect
• Higher assembly density
Item
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Capability
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Material
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FR4 Tg 140C/150C
FR4 High Tg 170C/180C
FR4 Halogen-Free
FR4 Halogen-Free & High Tg
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Board Type
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Multilayer Rigid PCB
Multilayer Flex PCB
Rigid-Flex Multilayer PCB
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Layer Count
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1-32layers
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Board Dimension
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6mm*6mm - 600mm*700mm
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Board Thickness
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0.6mm - 3.2mm
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Copper Weight
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0.5oz - 6oz
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Min. Spacing/Tracing
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3mil/3mil
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Surface Finish
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HASL (lead & lead-free)
ENIG
Immersion Silver/Tin
OSP
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Min. Annular Ring
|
3mil
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Aspect Ratio
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10:1
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Min. Drilling Hole Diameter
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6mil, 4mil (laser drill)
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Other Techniques
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Blind/Buried Via
Gold Fingers
Press Fit
Via in Pad
Electrical Test
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Multilayer PCB boards can be served in so many industries including consumer electronics, medical care, aerospace, telecommunications, military, automotive, wearables, IoT etc. based on its benefits. PCBCart has been striving to provide high-quality multilayer PCBs for customers with full concerns in terms of design, cost and lead time. Contact us to find reliable experts of multilayer PCB manufacturing!
Helpful Resources:
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Single-Layer vs. Multi-layer PCBs
•
Multilayer PCB Benefits and Applications
•
Flex-Rigid Multi-Layer PCB Fabrication Process
•
Full Feature PCB Manufacturing Services from PCBCart