Linked Electronics Co., Limited is a professional PCB and PCBA
service provider for 20 years. Our professional OEM electronic
manufacturing services impress our customers in various fields
around the world. Since its establishment in 2002, Linked Electronics has accumulated a group of
engineers with more than ten years of manufacturing experience and
professional electronic components purchasing team. With ten years
of professional spirit, providing professional engineering services
(PCB layout design, SMT process technology solutions, etc.), PCB
manufacturing , electronic components purchase, supply chain
management, PCBA manufacturing (SMT and DIP), one stop integrated
manufacturing service from test, maintenance, aging test and
assembly to directional development. Our more than 800 employees
are proud to serve customers all over the world in various fields
including military electronics, aerospace, medical equipment,
industrial automatic control, new energy, automotive electronics,
wearable device, 5G communication, drone and LED display, etc. More
than 1500 customers have witnessed our growth over the past 20
We have 10000 square meters of dust-free workshop and more than 800
employees, more than 30 production lines including PCB
manufacturing, SMT, DIP, automatic welding, aging test and assembly
etc. The equipment includes over 50 SMT machines from Japan and
Korea, automatic solder paste printing machine, automatic stencil
test machine, automatic stencil cleaning machine, automatic first
sample test machine, SPI solder paste on-line detector, 12
temperature reflow soldering machine, on-line AOI detector, X-ray
detector, lead-free wave soldering machine, automatic DIP machine,
automatic PCB splitting machine, PCBA auto clean machine, automatic
coating machine, intelligent MES electronic material management
system etc., with a daily output of 40 million points. A variety of
production line configuration can meet all kinds of demands from
sample order (lead time 24-hours) to mass production delivery. Our
products have passed through many testing procedures, strictly
implemented the quality system standards. We have obtained ISO9001,
ISO14001, IATF16949 series of system certification and recognized
as a national high-tech enterprise. Since the establishment of the
company, we are committed to end-to-end one-stop manufacturing
solutions. With rigorous technology, excellent quality and fast
delivery, we have provided customers with the most convenient and
mutually beneficial electronic manufacturing services, and won
praise from domestic and oversea markets.
What is the definition of Multilayer PCB electronic printed circuit
Multilayer PCB is the multi-layer printed circuit board that is
composed of three or more electronic layers. This is made up of a
substrate layer, which has a conductive metal on top and bottom
sides. It also offers enhanced functionality. They are utilized in
complex devices which require a very high number of connections.
Multilayer PCB boards includes at least three layers of conductive
layers. This multilayer PCB laminating process means pressing FR4
core and PP together.
Both of them are laminated under high hydraulic press pressure and
temperature condition. This process will melt prepreg which later
make the prepreg to join these layers together.
Multilayer PCB Manufacturing Steps
The manufacturing process of multilayer circuits takes several
complicated steps which much more difficult and complex than
doubled sided PCBs.
PCB Layout--That is the process by customer engineer
Printed Circuit boards should be rigorously compatible with, a PCB
layout created by the engineer designer using PCB design software.
Here is some of the commonly-used PCB EDA software, Altium
Designer, OrCAD, Pads, KiCad, Eagle etc. NOTE: Before the PCB
fabrication, designers should inform their contract manufacturer
about the PCB design software version used to design the circuit
since it helps avoid issues caused by discrepancies.
Once the PCB design is approved for production, designers export
the design into format that PCB manufacture accepts and the
frequently used program is called extended Gerber in the format
The PCB industry birthed extended Gerber as the perfect output
format. Different PCB design software possibly calls for different
Gerber file generation steps, they all encode comprehensive vital
information including copper tracking layers, drill drawing,
apertures, component notations and other options. All aspects of
the PCB design undergo checks at this point. The software performs
oversight algorithms on the design to ensure that no errors go
undetected. Designers also examine the plan with regard to elements
relating to track width, board edge spacing, trace and hole spacing
and hole size.
After a thorough examination, designers forward PCB file to PC
Board Houses for production. To ensure the design fulfills
requirements for the minimum tolerances during manufacturing
process, almost all PCB Fab Houses run Design for Manufacture (DFM)
check before printed circuit board fabrication.
Printing of the PCB Design
PCB printing begins after designers output the PCB schematic files
and manufacturers conduct a DFM check. The PCB manufacturers use a
printer called a plotter, which makes photo films of the PCBs, to
print circuit boards. PCB manufacturers will use the films to image
the PCBs. Although it's a laser printer, it isn't a standard laser
jet printer. Plotters use incredibly precise printing technology to
provide a highly detailed film of the PCB design.
The final product results in a plastic sheet with a photo negative
of the PCB in black ink. For the inner layers of PCB, black ink
represents the conductive copper parts of the PCB. The remaining
clear portion of the image denotes the areas of non-conductive
material. The outer layers follow the opposite pattern: clear for
copper, but black refers to the area that'll be etched away. The
plotter automatically develops the film, and the film is securely
stored to prevent any unwanted contact.
Each layer of PCB and solder mask receives its own clear and black
film sheet. In total, a two-layer PCB needs four sheets: two for
the layers and two for the solder mask. Significantly, all the
films have to correspond perfectly to each other. When used in
harmony, they map out the PCB alignment.
To achieve accurate alignment of all films, registration holes
should be punched through all films. The exactness of the hole
occurs by adjusting the table on which the film sits. When the tiny
calibrations of the table lead to an optimal match, the hole is
punched. The holes will fit into the registration pins in the next
step of the imaging process.
Print the Copper Utilized for the Interior Layer
This step is the first while making the inner layer of the PCB. You
print the multilayer PCB design; then copper is re-bonded to the
FR4 or PP that serves as the PCB structure.
Discard unwanted copper
With the photo resist removed and the hardened resist covering the
copper that needs to be kept, the board manufacturing steps into
the next stage: unwanted copper removal. Just as the alkaline
solution removed the resist, a more powerful chemical preparation
wash away the excess copper. The copper solvent solution bath
removes all of the exposed copper. Meanwhile, the desired copper
remains fully protected beneath the hardened layer of photo resist.
Not all copper boards are created equal. Some heavy copper boards
require larger amounts of copper solvent and varying lengths of
exposure. As a side note, heavier copper boards require additional
attention for track spacing. Most standard PCBs rely on similar
Now that the solvent removed the unwanted copper, the hardened
resist protecting the preferred copper needs washing off. Another
solvent accomplishes this task. The board now glistens with only
the copper substrate necessary for the PCB.
Lamination of the PCB Layers
AOI will be performed to check that there will be zero defects for
the traces. Those can be bonded together. You can achieve this
process in two spes, which includes the lay-up and the laminating.
The entire operation undergoes an automatic routine run by the
bonding press computer. The computer orchestrates the process of
heating up the stack, the point in which to apply pressure, and
when to allow the stack to cool at a controlled rate.
Before you drill, the drill spot is located with an x-ray machine.
This helps in securing the PCB stack.
This process helps in fusing the different PCB layers making use of
Imaging and Plating of the Outer Layer
By doing this you are guarding the copper found on the outer layer
by applying the photoresist.
To protect the copper during the process, a tin guard is utilized.
This gets rid of unwanted copper. This also ensures properly
established PCB connections.
Applying Solder Mask
After cleaning the PCB panels, soldermask is applied onto both
sides of the PCBs
Silk print is printed onto the PCBs
The nearly completed board receives ink-jet writing on its surface,
used to indicate all vital information pertaining to the PCB. The
PCB finally passes onto the last coating and curing stage.
Electrical and Testing Reliability
A technician performs electrical tests on the PCB. The automated
procedure confirms the functionality of the PCB and its conformity
to the original design. At linked electronics, we offer an advanced
version of electrical testing called Flying Probe Testing, which
depends on moving probes onto the pads to test electrical
performance of each net on a bare printed circuit board. Another
advanced testing is fixture which is faster but expensive for
prototypes. The pins of the fixture will touch the pads and check
the conformity of the boards.
PCBs will be routed as per customer’s mechanic file after flying
probe test. For PCB using fixture test, the PCB will be routed out
before mechanic process.
Final inspection will be performed. This includes board thickness,
board warp and twist, any scratches etc. The errors rectified
before it is sent for delivery.
Materials Used in the Manufacturing of Multilayer PCB
The different materials utilized in manufacturing multilayer PCBs
are boards, copper foil, resin system, substrate, infused
fiberglass sheet. Using an alternating sandwich, you can laminate
these materials together.
All the planes of copper are etched and the plating through of all
internal vias is done before the layers.
Multilayer PCB: Advantages
Multilayer PCBs come with lots of great benefits. Some of them
• Higher assembly density
• Provision of high speed and high capacity, as a result of their
• Weight reduction of devices
• Elimination of connectors needed for multiple separate PCBs,
thereby simplifying its construction.
Multilayer PCB: Product Use
Multilayer PCBs can be used in many areas
They are used in manufacturing CAT scan, heart monitors, and modern
• Utilized in the production of high-speed circuits due to their
functionality and durability
• Used for headlight switches and onboard computers due to their
high functionality and heat resistant ability
• The running of machinery and industrial control system utilize
them due to their small size and durability.
• Consumer electronics such as microwaves and smartphones also make
use of multilayer PCBs as a result of their small size and
• Satellite applications, GPS, and signal information, also make
use of multilayer PCBs
• Used in the production of computer electronics that are utilized
in motherboard servers due to its performance and space-saving