PCB Manufacturing Process and Services
The manufacturing process of PCB is a complicated task that starts with the conception of a product and results in the fabrication of a PCB that can perform all its intended functions. During this process, a schematic is drawn up to represent the component connectivity. After the PCB manufacturing, testing and verification of the circuit design have been completed, the PCB will then be ready for assembly and components can be mounted or soldered to incorporated it into the product.
The manufacturing of a PCB from scratch involves a great deal of attention to detail, which must be maintained throughout the process. The manufacturing of the bare board is one step in this process that doesn’t get the attention it should get but is still very important. Because of the sophisticated software tools involved in its development, the PCB design process needs a great deal of attention. The manufacturing process will receive equal praise for contributing to the overall satisfaction of finishing the product.
The manufacturing of PCBs, however, is a hidden process, unknown to many people outside of the design industry. This article will discuss, in depth, the PCB manufacturing process and we will make it easy for you to understand it.
Table of Contents
PCB Manufacturing Steps
The process of manufacturing a printed circuit board begins with the design and verification stages and continues through the final production of the circuit boards. Because there are a lot of procedures, you need computer direction and machine-driven equipment to make sure everything is accurate and to avoid any fault in manufactured PCB. Before the finished circuit boards can be packed and shipped to clients, they are subjected to stringent quality assurance testing.
Following are main steps to manufacture a PCB.
As a first step, the designer will use a PCB design program to construct the appropriate PCB layout for compatibility considerations. This will be done to ensure that the final product works properly. Eagle, Pads, and Altium Designer are a few examples of well-known Printed Circuit Board design software that designers may choose to create the PCB layout.
Before commencing work on a PCB layout, the design team will collaborate with the PCB manufacturer to define the specifications and configuration of the physical board. This will take place before any work on the layout itself begins. This information is required for selecting the PCB manufacturing vendor that is most appropriate for the task. It is necessary to finish the basic design before beginning production of PCBs to guarantee accurate results. Even a straightforward modification to a component that was not synced between the layout and the schematic might result in an altered footprint and, therefore, a poorly constructed circuit board.
After the design has been created and given to the PCB manufacturer, the PCB manufacturer will need to provide their approval on the PCB design before manufacturing can begin. Next, the designer will need to export the design using a format that is acceptable to the PCB manufacturer.
The completed PCB design is then delivered to a PCB manufacturer, the fabricator performs a second check on it. This check is known as a Design for Manufacture (DFM) check. A thorough DFM inspection guarantees that the PCB design satisfies, at the very least, the tolerances that are necessary for production.
Film Making Stage
Transferring the PCB design circuitry picture data from the manufacturing files that were given by the customer to the board is the second stage in the production of a circuit board. Although the data will often arrive in a file format known as Gerber, it is possible to use a variety of different formats and databases. The data pertaining to the images will be sent to the board utilizing one of the following two distinct procedures:
This is standard imaging method that is used in the production of printed circuit boards for as long as mass-produced circuit boards have existed. The pictures of the designed circuitry will be created on film by a precision photoplotter, and the film will serve as a template for printing the images onto the circuit board during the manufacturing process.
The use of photo tools has been omitted thanks to the utilization of a laser that prints the pictures of the circuitry straight onto the circuit board. When compared to the usage of film, this method is superior since it is more exact, there are no alignment problems, and photo tooling won’t need to be periodically recreated to replace films that have become worn out. On the other hand, each layer will have to undergo the more time-consuming and costly process of individual laser printing.
Substrate Layering Stage
Multilayer PCBs consists of several layers of dielectric material and copper. PCBs is made up of layer with a dielectric core material of epoxy resin and glass fiber more generally known as FR-4, which is sandwiched between two layers of copper foil. The FR-4 core material is what gives it its common name. Although there are various dielectric materials available, the production of printed circuit boards typically makes use of FR-4 as the core material.
To construct the stack up of multilayer boards, a smaller version of the same core structure that was utilised in the production of double-sided boards is laminated along with additional core structures. For the finished result to be of high quality, each layer needs to have its width, copper weight, and alignment with subsequent layers carefully monitored and regulated.
Copper Printing for Inner Layers
Following the process of printing the circuit board design onto a piece of substrate material, a layer of copper foil or a copper coating is placed onto it. After that, the copper is pre-bonded to the same piece of substrate that previously served as the framework for the PCB. After this, the copper is etched away to expose the blueprint that was created previously.
A photo-sensitive film, called resist, is applied over the substrate panel so that it can no longer be seen. The resist consists of a layer of photo-reactive compounds that, if subjected to ultraviolet light, become brittle and form the barrier. The resist enables the technicians to achieve a flawless match between the photographs of the blueprint and the circuit that is printed onto the photoresist.
After the resist and the substrate/laminate are aligned with the holes that were created previously, a burst of UV light is directed at the two materials. The photoresist is made opaquer because of the passage of ultraviolet light through the film’s transparent areas. This denotes regions of copper that are to be preserved in their original state as passageways. In contrast, the black ink stops any light from penetrating the parts that aren’t supposed to harden so that they may be deleted later. This allows these sections to be etched away.
After the preparation of the board is complete, it is washed in an alkaline solution to eliminate any residual photoresists that may have been present. After that, the surface of the board is given a thorough cleaning with a power washer, and it is then allowed to air dry.
After drying, the only resist that should be left on the PCB is the layer that sits atop the copper that, if the PCB is ultimately popped free, will stay as a component of the PCB. A technician inspects the PCBs to ensure that they are free of any mistakes. If there are no mistakes, then it’s time to move onto the next stage.
Layer Laminating Stage
Layer of PCB are placed on top of one another to produce what is known as the final “printed circuit board.” Thin layers of copper foil are used to cover the exterior surfaces of the top and bottom sides of the board. Each layer pair will have a sheet of “prepreg” sandwiched in between them so that the layers may be bonded together more easily. The term “prepreg” refers to a substance made of fiberglass that has been impregnated with epoxy resin and is designed to melt because of the heat and pressure experienced during the lamination process. When the prepreg has reached the desired temperature, it will glue the layer pairs together.
During this step, putting the components of the board together called “compositing” takes a great deal of attention to detail to preserve the proper alignment of the circuitry on the various layers. After the stack up has been finished, the layers are sandwiched together and then laminated. During the lamination process, heat and pressure are used, which fuses the layers together creating a single circuit board.
Drilling holes in the board is the next stage in the manufacturing of printed circuit boards. These holes are used for component mounting, thru-hole vias, and the non-plated holes of mechanical features. The bulk of the thru holes that are used in a circuit board will be plated. Because of this, the holes are often drilled 0.005 millimeters bigger than the size that is needed for the final hole so that plating may take place. The fabrication of any blind and buried vias or laser-drilled micro-vias occurs before the lamination of the board if the design calls for any of those features. The additional processing steps necessary to create these vias can result in an increase in the cost of the circuit board’s manufacturing, but they may be necessary to achieve dense circuitry and/or optimal electrical performance.
After the holes have been drilled, they go through a cleaning procedure that combines chemical and mechanical methods to remove resin stains and debris that were created by the drilling process.
Outer Layer Copper Plating Stage
After that, a chemical coating of a very thin layer of copper is applied over the entirety of the board’s exposed surface, including the interior of the holes. This produces a metallic layer that will be used in the subsequent stage, which involves electroplating more copper into the holes and onto the surface. A micron-thick layer of copper is deposited over the topmost layer and into the holes that have just been drilled as part of this plating process. This layer is applied to the layered board, which results in the layered board being covered with a copper coating.
The purpose of the holes, prior to their being filled with copper, is merely to reveal the fiberglass substrate that is found on the interior of the panel. Copper is poured into the holes, which covers the walls of the holes that were previously bored.
Outer Layer Imaging and Etching Stage
At this stage in the process, the photoresist is only applied to the outermost layer. Following the coating of the outside layers in photoresist and the imaging process, the outer layers of the PCB are next plated in the exact same manner that the internal layers of the PCB were plated in the stage before this one. However, even though the procedure remains the same, the outer layers are plated with tin, which helps protect the copper that is present on the outside layer.
When it comes time to etch the outermost layer for the last time, the tin guard is utilised to assist in protecting the copper while it is being etched. Tin is used to shield the valuable copper in the etching region from the copper solvent, allowing any undesired copper to be removed using the same copper solvent that was used before.
One of the most significant distinctions between the etching of the inner layer and the etching of the outer layer covers the regions that require removal. These inks are inverted for the outer layers, such that dark ink is used for conductive regions and clear ink is used for non-conductive surfaces. Inner layers employ dark ink for conductive areas and clear ink for non-conductive surfaces. The transparent ink makes it possible for the tin plating to cover and protect the copper underneath it. During the etching process, engineers remove any excess copper as well as any leftover resist coating to get the outer layer ready for solder masking.
Automated Optical Inspection
The automated optical examination must also be performed on the outer layer. During this optical inspection, we check to see if the layer satisfies all the design specifications exactly. Additionally, it ensures that the preceding procedure successfully eliminated any excess copper from the layer to produce a PCB that can work correctly and will not produce incorrect electrical connections.
Solder Mask & Silk-Screening Stage
Before the solder mask can be applied, the PCBs must go through a meticulous cleaning process. After being cleaned, the surface of each PCB is covered with a coating that is composed of ink, epoxy, and solder mask. After that, ultraviolet light is flashed on the boards to determine which areas of the solder mask need to be scraped off. After the solder mask has been removed from the circuit board by specialists, the board is next baked in an oven to cure the mask. The copper on the board is given an additional layer of defense from the corrosive and oxidative effects of the environment with the help of solder mask.
In addition to the solder mask, various PCB markings and component reference designators are silk-screened onto the PCB. By placing the circuit board in an oven at a certain temperature for a certain amount of time, the solder mask and the silkscreen ink will both get cured. Fabricators of PCBs must utilize a technique known as silkscreen application or legend printing to print essential data on the surface of the board. This is necessary since PCBs need to have information directly on the board.
Inspection & Testing Stage - Final Stage
The completion of the PCB manufacturing process finishes in the preparation of the PCB for assembly process. If it is required to do so, PCBs are routed out of their manufacturing panels, or the panels are prepared for breakout following assembly. This may be accomplished e ither by scoring a V-cut on the board outline or by routing out the board completely.
Testing for continuity is performed on the completed PCBs using automated test equipment such as a bed of nails test fixture or a flying probe test system. During the tests, any accidental shorts between the nets, which would render the board useless, are looked for. When all the testing is done and the board has been given a satisfactory report, the PCB is sent to the clients or to the assembly line for component placement.
ELE Technology Co. the Leading PCB Manufacturer
ELE Technology has been serving the electronic industry with high-quality and printed circuit board assemblies (PCBA) for more than 15 years. The company’s manufacturing and management are located in Shenzhen and Huizhou, China. We can produce printed circuit boards with 0 to 24 layers, as well as quick-turn prototypes and full turn-key assemblies.
PCB Manufacturing Services Offered by ELE
We are expert in PCB manufacturing, and we offer a wide range of manufacturing services including the manufacturing of following types of PCBs,
- – FR-4 PCB
- – Multi-layer PCB
- – Flex PCB
- – Rigid-Flex PCB
- – Metal Base PCB
- – Impedance Control PCB
- – High Density Interconnect PCB
- – High Density Multilayer PCB
- – High-TG PCB
- – Heavy Copper PCB
- – Special PCB-Advanced High Frequency PCB
Our team of highly trained engineers performs a DFM check on every Gerber file that is provided. In accordance with IPC-A6012 Class 2 or other standards, each PCB is put through the quality assurance process. Choose ELE Technology today, and you will save a lot of time on your project and work.
Click Here for a comprehensive rundown of the PCB fabrication capabilities offered by ELE Technology Co., we cherish you as a client and look forward to serving you for the many next years to come.