|
Multi-layer PCBs are printed circuit boards with more than two layers of copper,
such as 4-layer, 6-layer, 8-layer, 10-layer, 12-layer, and so on. With
advancements in technology, it is now possible to manufacture PCBs with 20 to 32
layers of copper.
This structure allows engineers to allocate different layers for various
functions, such as power distribution, signal transmission, EMI shielding, and
component mounting. To manage the complexity and avoid excessive layering,
buried vias and blind vias are often incorporated into multi-layer PCBs. For
boards with more than 8 layers, high
Tg FR4 material is preferred over standard Tg FR4 due to its
enhanced thermal properties.
The manufacturing process becomes more complex and costly as the number of
layers increases. Consequently, the lead time for multi-layer PCBs is typically
longer compared to standard PCBs. For precise lead time, please contact us directly.
|
|
A multi-layer PCB is a complex and sophisticated printed circuit board that
consists of multiple layers of conductive copper and insulating material. Here’s
a detailed breakdown of its structure:
- Core Material
FR4 Core: The central layer is typically made of FR4, a
fiberglass-reinforced epoxy laminate that provides structural integrity
and
insulation. This core material can also be a pre-preg (a composite
material
made of fiber reinforcements pre-impregnated with a resin matrix).
- Copper Layers
Inner Layers: Multiple inner layers of copper foil are
laminated onto the
core material. These layers are used for routing electrical signals, power
distribution, and grounding.
Outer Layers: The top and bottom layers are also copper
foils, which can be
used for component mounting and additional routing.
-
Pre-preg (Pre-impregnated Composite Fibers)
Insulating Layers: Between each copper layer, there are
layers of pre-preg.
This material acts as an insulating barrier and provides mechanical strength
to the PCB. The pre-preg layers are cured and bonded under heat and pressure
during the lamination process.
- Vias
Through-Hole Vias: These vias pass through the entire PCB,
connecting all
layers.
Blind Vias: These vias connect outer layers to one or more
inner layers but
do not go through the entire board.
Bured Vias: These vias connect only the inner layers and
are not visible
from the outer layers of the board.
- Solder Mask
Protective Coating: A layer of solder mask is applied to
the outer surfaces
of the PCB. This layer protects the copper traces from oxidation and
prevents solder bridges during component soldering.
- Silkscreen
Identification Markings: The silkscreen layer is applied on
top of the
solder mask. It includes printed information such as component labels,
logos, and other identifiers.
|
