Summing Up The PCB Manufacturing Process
Nothing can connect electronic devices electronically better than printed circuit boards. PCBs are one of those aspects that form an integral part of everything ranging from personal electronics to even airplanes. Just as how easily they have been simplifying functioning and enhancing the performance of electronic devices, they aren’t as simple to manufacture; in fact, the complexity of the process, along with the expertise and skills required, is precisely one of the primary reasons why businesses choose to outsource printed circuit board prototype production.
There are a lot of things that need to be considered and followed during the PCB manufacturing process. Here is a quick summary of the step-by-step procedure:
Step#1 – Film Generation
This film is typically created for copper and soldermask layers and is made from photographically exposed mylar. These films are generated from the design files that are provided from clients. The PCB manufacturers then create a replication of the film. Every Gerber file that’s submitted by the client to the PCB prototype manufacture embodies a single layer of the PCB.
Step#2 – Selection of Raw Material
As per the industry standards, 0.059 inches thick FR-4 laminate copper is used on both sides. Moreover, panels are sized to accommodate multiple boards.
Step#3 – Drilling of Holes
The files submitted by clients are thoroughly analyzed for drilling holes appropriately. Normally, these holes are drilled using NC drill machines and carbide drill bits.
Step#4 – Electroless Copper
In order to allow the drilled holes to connect with various layers of the PCB electronically, a very thin layer of copper is chemically arranged through the holes. During further stages, this copper is solidified through electrolytic copper plating.
Step#5 – Application of Photo-Resist and Image
To allow the transfer of PCB design from the CAD data to the bare circuit board, PCB manufacturers begin by applying photosensitive photo-resist onto the panel. This application covers the entire circuit board. Then, a copper layer film is placed over the board while a high-level UV light source renders the remaining portion of the board. Then, the board is developed chemically and all the unexposed photo-resists are eliminated from the panel, producing traces and pads.
Step#6 – Pattern Plate
During this step, the copper thickness is built through the holes and onto the board’s surface through an electrochemical process. Once done, an additional layer of tin plating is made onto the surface. It is this layer that protects the platted copper during the etching process.
Step#7 – Stripping and Etching
First, the photo-resist is chemically striped from the panel and then the new exposed copper is etched from the board. By this stage, the elementary circuitry of the PCB is clear and precise. Lastly, the tin layering is striped to expose the copper circuitry.
Step#8 – Soldermask
Now, the board is fully covered with liquid soldermask. Through the use of UV light sources and films, the areas that need to be soldered are highlighted. Fundamentally, the real purpose of the solder mask is to protect the copper on the board from oxidation, corrosion and damage.
Step#9 – Silk Screening
In this step, the PCB manufacturers print other information that’s present in the files submitted such as designators and logos. This process has a high similarity with the inkjet process that specifically designed for PCBs.
Step#10 – Application of Surface Finish
The final surface finishing is applied to the board which can be of tin/lead solder, immersion silver, immersion gold, flash gold, ENIG, gold finger, HAL and HAL lead free. The sole purpose of the surface finish is to prevent oxidation and allow soldering of the PCB components.
Step#11 – PCB Fabrication
The perimeter of the PCB is routed from the larger panel through the NC equipment. At this stage, the PCB manufacturing gets completed.