A Comprehensive Guide to PCB Manufacture Process

Printed circuit boards, or PCBs, are the building blocks of nearly all contemporary electronics. Through several intricate processes, the PCB manufacturing services turn raw laminates into boards that are ready to assemble. This manual offers a thorough rundown of all the main steps involved in PCB fabrication, from sourcing raw materials to conducting final testing. 

We will examine the critical phases, technologies, and techniques for quality control employed expertly for PCB manufacturing in the UK. Comprehending the entire production process aids designers in optimising their layouts for manufacturing while guaranteeing that the finished boards fulfil quality and reliability standards.

What is the Procedure For Making PCBS? 

The printed circuit board (PCB) manufacturing process necessitates a complicated method to guarantee the performance of the final product. Although circuit boards might be single, double, or multilayered, the manufacturing techniques employed only change once the initial layer is produced. 

The complexity of printed circuit boards is correlated with the number of stages involved in their production. Any step skipped, or the process shortened could have a detrimental effect on the circuit board’s functionality. Nevertheless, the PCBs should function correctly as essential electronic components after they are finished.

Process of PCB Manufacturing

PCB manufacturing or fabrication starts after the manufacturer receives your final manufacturing files and the PCB design is approved. Here’s where the design you created virtually for your circuit board manifests as a printed circuit board.

Step 1: Perceiving The Design

After several checks, it’s time to print your PCB board design. Plotter printers are specialised printers used by PCB board manufacturers to create films from circuit board design files. These films are comparable to your schematic diagram’s photo negatives.

The interior PCB layers are printed with two different ink colours:

• Clear ink denoting the non-conductive portions of the PCB, such as the fibreglass base; 
• Black ink depicting the copper traces and wiring of the PCB.

Additionally, the films provide a registration hole so that printed circuit boards can be aligned later in the manufacturing process. The movies will be kept in a secure location to prevent unwanted interaction.

Step 2: Printing Inner Layers On Copper 

The actual PCB manufacturing process starts at this point in the manufacturing cycle. It begins with a PCB in its most basic form, a laminate board constructed from the substrate material. Glass fibre and epoxy resin are typically used as the substrate materials. 

• The photo-sensitive material is applied to the laminate board. After the PCB design has been printed onto it,
• Copper has been pre-bonded to both sides of the board, and copper has been etched away to show the PCB design according to the film.
• Further, the laminate board is covered with photo-sensitive film, namely resist.

Step 3: UV Rays Blazing

The resist consists of a photoreactive coating of chemicals. This layer of photoreactive compounds is hardened by ultraviolet light, which we apply to the resist-covered laminate boards.

• The photoresist is hardened by UV light passing through the translucent parts of the film. 
• However, UV light cannot harden the areas covered in black ink. 
• The remaining portion of the board is slated away. 
• The photoresist residue is removed from the board in an alkaline solution. 
• Any residue is then removed with a final pressure wash. 
• Finally, the board is dried. A technician checks the board for errors before proceeding to the next step.

The goal of UV light blasting and photoresist is to guarantee that the real PCB is manufactured precisely according to the schematic blueprints.

Step 4: Etching 

Once the unexposed photoresist is removed, the inner layer’s intended copper pattern is seen. The intended circuit is then preserved by removing the leftover copper using a chemical solution. Each inner layer is subjected to this technique once more.

Step 5: Layer Alignment

After cleaning, the laminate boards are prepared for layer alignment. To align the inner and outer layers, we often use the optical punch, a specialised machine that inserts a pin through the registration holes.

Step 6: Visual Examination

Experts use an optical punch machine to align the clean layers during optical inspection to guarantee accurate placement. Since mistakes cannot be fixed once the layers are built, this procedure confirms that the PCBs are flawless. Electronic scans with laser sensors are performed using an Automated Optical Inspection (AOI) system, and the PCBs are compared to the original designs. After imaging and etching, defective circuit boards are disposed of, and the procedure is repeated for the outer layers.

Step 7: Layer Lamination: 

The inner layers are carefully laminated with their corresponding circuit designs after being etched. The core of the PCB is formed by permanently joining these layers into a cohesive unit using heat and pressure.

Step 8: Drilling

To produce vias for electrical connections between layers and to mount components, precisely placed holes are drilled through the whole PCB stack-up.

Step 9: PCB Plating 

Plating comes next after drilling. The process of PCB plating involves inserting copper into the drilled holes to permit current to flow from the board’s surface to its inner layers, between two layers, or between two surfaces. Several chemical baths are involved in the procedure. 

Step 10: Imaging and Etching of the Outer Layers

The copper traces and pads on the top and bottom part of the printed circuit board, where electronic components are to be installed, are defined by the same photolithography and etching procedures used for the inner layers. 

Step 11: Application of the Solder Mask 

The PCB surface is covered with a protective solder mask. This mask ensures accurate solder connections only at specific spots by covering areas that shouldn’t get solder during the assembly process.

Step 12: Silk Screening

When anything is silk-screened, an ink-jet printer prints all of the information directly onto the board. Using a silkscreen printing technique, identifying identifiers such as logos and component reference designators are printed onto the PCB surface. These markers provide important information for future maintenance and assembly.

Step 13: Surface Finishing

The exposed copper surfaces of the PCB may be electroplated with a thin layer of metal, such as nickel or gold. This coating improves the PCB’s general longevity, corrosion resistance, and solderability.

Step 14: Electrical Testing and Inspection 

The finished PCB undergoes extensive electrical testing to guarantee correct operation and find potential flaws. This could entail sophisticated X-ray analysis, optical inspections, and electrical continuity testing.

Step 15: Profiling

Profiling is the final stage of the PCB manufacturing process. The printed circuit boards are one single panel up until this point. Individual boards are cut from the PCBs using the original design files. The two most popular methods for dividing PCB boards are V-groove and scoring. With profiling, breaking apart the PCB boards is simple.

Step 16: Final Quality Check

Every printed circuit board undergoes a last visual examination and quality evaluation after profiling. The following checks help identify PCBs that are error-free and functional: 

• Fixing any boards that don’t pass PCB inspections and testing them again 
• Ensuring that every PCB precisely complies with the design parameters assigned to it 
• Checking each completed PCB for burrs or sharp edges 
• Ensuring that the hole dimensions in every layer are precisely aligned 
• Verifying that the hole sizes precisely correspond to the design specifications 

Step 17: Packing & Shipping 

The completed PCBs are shipped to the customer in a protective package to guard against damage during transit.

Designers and engineers can optimise their layouts while fulfilling all fabrication and quality standards by thoroughly understanding the entire PCB manufacturing services and process. The final boards are made with minimum complications and achieve cost requirements primarily due to effective communication between the fabricator and designer.