Guideline

Mastering the Art of PCB Board Preparation: A Step-by-Step Guide

PCB Board Production Steps

Printed circuit boards, or PCBs, are the building blocks of nearly all contemporary electronics. Manufacturers use sophisticated processes to create operational PCBs from the bare board they receive. If you are wondering how to prepare PCB board for use in electronic gadgets, we can give you a step-by-step guide to PCB board preparation.

Let us examine the types of circuit boards used, important phases of the preparation, and techniques for quality control employed in expert PCB manufacturing because comprehending the whole production process will help you understand the system thoroughly.

PCB Types

Before talking about how to prepare PCB board, we will know the basic types of PCBs first. There are three commonly used types of PCB boards that one can choose from before starting the preparation and manufacturing process.

  • Rigid Boards: The largest number of PCB boards that designers encounter are rigid boards. Ordinarily, these pieces are constructed from strong materials, although depending on the particular needs of the layout, they might be altered to improve particular aspects of the design.
  • Flexible Boards: Because they are made of a less stiff substance, flexible boards have far higher deflection, and the board is often much thinner than a typical rigid board. The material of these boards is similar to a film roll, although flexible boards are already widely used, it is hoped that they will bring technology to the next level and eliminate the limits that rigid boards now have.
  • Metal-core Boards: The emergence of metal-core printed circuit boards, with a greater ability to diffuse heat across the surface of the board, is primarily attributed to inflexible board layouts. This procedure protects sensitive electronics and could be a great substitute for other commonly used boards to prevent PCB failure due to overheating.

PCB Board Preparation From Design to Finish

A printed circuit board has to be designed and prepared before it can be constructed for use. Listed below are the steps one needs to follow for PCB board preparation and design.

PCB Board Preparation

1. Electrical Schematic

Make sure that the library part designs are finished before using the CAD tools to begin the board’s design, and this entails drawing symbols for the components that will be used in the design, such as integrated circuits (ICs), resistors, capacitors, inductors, and connections. A wiring that shows the connection between terminals of the design can be created. Elements must be moved as necessary throughout the diagram to create a clear and understandable design.

2. CAD Parts Library

Creating CAD parts library required for the design is the initial stage, and this will feature step models for 3D printed circuit board display, footprints for PCB layout, and schematic symbols. Making a schematic of the circuitry’s logical representation comes next, once the libraries are prepared, then the symbols are placed on a schematic sheet using CAD software, and they are then connected to create the circuitry.

3. Layout Design

During the construction phase of the circuit architecture, schematics connections are obtained and converted into the nets that interconnect more than one constituent connections. With a schematic of the necessary panel shape shown on the monitor, the configuration creator will place the item’s imprints in the proper locations. After the aforementioned components are positioned correctly, the following stage in attaching the netting to the connections is to create the paths and surfaces between each of the points. Layout rules limit the amount of contact between tracing on different netting and control various other lengths and gaps needed for an entire layout that can be included into the design software.

4. Production Data Package

The outcome of the printed circuit board design is kept inside a standard program called Gerber which is later sent to the manufacturer for easy transmission of accurate data. The solder mask layers, component notations, and copper layers are defined in the Gerber files, and the manufacturing data package also comes with basic specs, and a drill file.

5. Circuit Simulation

After all of the parts and netting are assembled and organized in accordance with the blueprint, the next challenge is to verify whether the electrical system will function as planned. Before building the actual equipment, utilize circuit models with a modeling program to verify that the design works. PCB engineers may test the circuits they are designing with the help of these tools, which is why these tools are a crucial component of the PCB design process as they may save both time and money.

6. CAD Tool Setup

Numerous instruments available to PCB architects help their capacity to set layout guidelines and limitations that will keep different nets from crossing while maintaining proper distance between items. Other instruments available to the programmer include designing lines that are often employed to efficiently and neatly organize elements and path lines.

7. Manufacturing Panel Preparation

To maximize consumption of materials, conventional fabrication boards are employed by most designers. However, the production panels need to be constructed according to the printed circuit board specifications and production specifications that must be kept in mind.

8. Phototooling

A film is made for every PCB assembly layer board using a laser plotter and is placed in a dark, climate-controlled chamber. To ensure precise alignment between the layers, the films are registered with one another. During the UV exposure procedure, the films are aligned using the punched registration holes.

9. Component Placement

After appropriately configuring your design database and importing the network connectivity data from the schematic, the next step is to physically lay out the circuit board. The element’s traces have to be placed inside the software system framework to know which portions each imprint links with. The net connections will be shown as a “ghost-line” graphic for each footprint, and designers will be able to arrange these components for optimal performance while taking into account physical obstacles like cables, connections, and hardware. Nevertheless, in order for the producer to combine the pieces as efficiently as possible, architects additionally are required to consider where they should place them.

10. Using the Base Material

The substance known as FR-4 is usually used for this particular purpose and the copper foil covers both ends of the glass filaments and epoxy resin that comprise the center of the innermost layer. Both sides of the innermost layer of the metallic wrap are thoroughly treated to remove oxidation and other impurities. To provide adequate mechanical adhesion, the copper surface is simultaneously roughened by the moving brush rollers.

11. Dry Lamination

The central substance is passed across the pre-heated rollers combination, which is maintained at an internal temperature that is higher than 100 degrees Celsius. Since the surface is photosensitive, only the yellow light region is used for further processing of the PCB.

12. Exposure on Inner Layers

After applying film to the laminated material, the laminate layer is subjected to a UV light of high intensity. The printed circuit board lines are visible when the underneath lamination has been subjected to ultraviolet rays and these marks will eventually harden when the illuminated region is subjected to chemical-based processing.

13. Etching of Inner Layer Core

Another round of spraying, rinsing, and drying is applied using an acidic solution this time. The speed of the process will depend on how thick the layers of copper are because the conductive pattern’s fineness is constrained by thicker copper layers.

14. Automatic Optical Inspection

During the PCB board preparation process, the next step is automatic optical inspection. Interior sections undergo a computerized optical inspection to detect holes and other faulty systems, as well as a checking of suitable circuitry design concerning the initial layout information.

15. Braun Oxide Preparation

The innermost coatings go through a chemical-based surface-preparing stage that alters the outermost layer in order to increase the bonding of these two layers before the laminating procedure begins. This process ensures that the next stages are successful.

16. Stack-up

Layers are piled together before being laminated, and the stacking starts with a bottom layer of copper foil and prepreg layers are placed on top of the copper layer. This process is followed by more prepreg layers between the inner layers and a second copper foil on top of the inner layers.

PCB Board Preparation Stackup

17. High Pressure Lamination

Laminating the stacked layers involves applying pressure and heat to ensure a high-quality finish, and several PCBs are pressed at once, spaced apart by separators. The PCB becomes fused by force as the epoxy resin melts and solidifies under the influence of high pressure and rising temperatures.

18. Trimming

This process maintains the act of cutting off the reflective substance that extends out of the fused surface to produce an even board that mimics an insulated component.

19. X-ray Analysis

X-ray is used as a preliminary step to identify the unseen pads in the inner layers because the pads can easily be found, and new reference holes can be calculated for the drilling through X-ray analysis.

20. Drilling

A CNC drilling machine with a maximum speed of 280,000 revolutions per minute is used to create the PCB. For the holes to be plated with high-quality copper, they must be as smooth and cleanly drilled as possible. The panels are sandwiched between an upper aluminum sheet and a base plate. The top plate made of aluminum keeps the drill from deflecting and avoids burrs, and the panel’s surfaces are shielded from harm and scratches by the plates.

21. Brushing and Desmearing

Following the drilling process, oscillating and spinning brush rollers are used to mechanically brush the surface. To clean the drilled holes and get rid of any residue that could have spread on the copper, use oxygen plasma or a permanganate solution because the appropriate electrical conductivity between the traces in the layers and the hole plating may get impeded by resin residues on the copper.

22. Electroplating

To provide a link of electricity among various layers and bored openings, conductivity is established with a copper covering constructed using chemical procedures. This inductive coating serves as the foundation for a later process that uses a substrate.

23. Dry Lamination of Outer Layers

This procedure is the same as the one used in the inner layers and the panel gets run through a pair of heated rollers that are around 110 degrees Celsius.

24. Development and Exposure

A negative exposure mechanism is applied in this procedure. The conducting wiring needs to be copper-plated before being used and these parts are not covered with the epoxy. However, the areas that connect the wiring are covered with polymer that have been laminated.

25. Electrolytic Copper Plating

Every opening and wire has a receptive covering and the apertures in layering link each conductor through electricity. For there to be an effective electric connection, there should be copper present on the exterior surfaces of the openings. Consequently, the overall copper thicknesses on the topmost layer must have a specific thickness which should be maintained during the plating process.

26. Solder Mask

Printed circuit boards require a soldering overlay to safeguard the metal area that will not be joined during the procedure and to insulate it from damaging soldering connections when the assembling process starts. On each side of the board, a soldering overlay print covering is placed by using a producer that utilizes an ultraviolet (UV) printing for hardening the soldering iron mask. The soldering cover is removed from the areas that should be viewable by the person who is handling the panels in question.

27. Surface Finish

The surface finish is provided to the copper areas that were not protected by a soldering shield and this treatment protects the metal before all the parts are assembled and connected to the printed circuit board.

28. Routing

It’s now time to join the nets after the parts have been arranged though they can be rearranged as necessary. The rubber-band net connections get transformed into sketched traces and planes to do this. The designer may do this thanks to a variety of capabilities included in CAD software, such as time-saving automatic routing functions. When routing, great care must be taken to ensure that the nets do not traverse areas of severe noise and that their length is appropriate for the signals they are conveying. This may lead to signal integrity issues like crosstalk, which might impair the performance of manufactured boards.

Conclusion

After reading this blog post, you may have a brief understanding of how to prepare PCB board. It is never an easy task for professionals or beginners to master PCB board preparation. For further information, please visit https://www.viasion.com.

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