Drilling
For the multi-layer circuit board transmit signals between layers holes need to be drilled or lasered into to create
vias that connect the layers. Drilling is different based on the kind of via that is being utilized and is usually
performed using a set of 2-3 panels at one time. The final product will typically be five millimeters larger than the
finished product because these holes are coated with copper to send electrical signals via the Electroless Copper Deposition.
Hidden and blind vias need to be constructed prior to that process of laminating. Incorporating these vias to
your PCB design may raise the price due to additional steps to be followed.
Electroless Copper Deposition & Dry Film Outer Layer
After holes are made in the substrate, any excess resin and debris is cleaned by using mechanical and chemical
processes. After that, a fine layer of copper is then deposited across all exposed surfaces of the panel, forming
an aluminum foundation for an electroplating. Like the development/etch/strip method that was previously used,
dry film is sprayed onto the outside on the panel. It is exposed to direct laser imaging and leaves a conductive
pattern.
Electroplating, Stripping, and Etching
With the pattern that conducts and drill holes visible the panel is then set in an electroplating bath of copper
that is enriched with sulfuric acid, as well as copper sulfurate. When an electrical charge is added to this bath
the bath, copper is deposited on the surface that conducts electricity on the board in an average thickness of 1
millimeter. The plate is removed and placed in an etching bath with tin for use to act as an etching barrier.
After plating is complete The drying film will be removed, and the exposed copper that was not covered by tin, is
removed leaving only the trace pads, as well as other designs that are left on the plates. The remainder of the tin
is chemically removed and only the copper remains in the precise zones.
At this moment your printed circuit board has been put together, but it's still not yet ready to be assembled.
Solder Mask, Silkscreen, and Surface Finish
Prior to moving on towards step 3: PCB assembly stage The printed circuit board is secured with an solder mask
that has the same UV exposure as at the time of the photoresist. This gives the printed circuit board its
distinctive green hue, but other colors are also possible.
Solder masks are an extremely small layer of polymer which shields copper traces printed on the board from the
oxidation. It also blocks solder bridges that are created when an unintentional connects two conductors, which
can compromise the function of a circuit printed board.
Solder mask color may be selected at this point However, the majority of manufacturers choose green as it is
helpful in detecting defects thanks to its bright contrast and visibility to trace, which is essential in the PCB
prototyping phase. The color of the Solder mask doesn't typically alter the function of a PCB, however the darker
shades are more prone to heat absorption and therefore not suitable for applications that require high
temperatures..
After the solder mask is been applied, the component reference designations and other board markings are
screened onto the circuit board. The silkscreened mask and solder ink cure by baking the circuit board inside an
oven.
The final step is to apply a surface polish is applied over metal surfaces that are not covered by the mask for
solder. This shields the metal and assists in the soldering process in the PCB assembly process.
Assembly Preparation, Inspection, and Testing
With the PC fabrication process completed The boards are then subjected to an array of checks and tests to
verify their performance prior to being assembled or shipped. Automated testing equipment is used to identify
any imperfections that might cause problems for the board. Any PCBs which fail the requirements are rejected.
CONSIDERATIONS FOR THE PCB FABRICATION PROCESS
PCB production is an time-consuming process, and even small errors can be costly for businesses due to poor
construction. When selecting your PCB fabrication firm, think about employing PCB fabricators that have a track
performance record. Imagineering Inc produces aerospace-quality PCBs and is able to handle both
manufacturing and assembly of PCBs. Our qualifications include:
• The turnaround time is as short as 24 hours
• High mix low-to-mid volume
• Inspections for Class Il as well as Class III
• As9100D-certified and ITAR certified and ITAR
• The lead and the leaded RoHS assembly
• 100% on-time guarantee
• Design and design services (Outsourced)
• Full box construction
If you're in search of the highest quality PCB fabrication firm Look at Imagineering Inc. Our pricing is reasonable
and our speed cannot be bettered. Get a quote for PCB fabrication from kingtech now.
