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PCB Manufacturing Process
Stage 1: Design
Using PCB design software, the designer should produce a PCB layout that is rigidly compatible with circuit boards. Software for designing PCBs that is often used includes Eagle, KiCad, Pads, OrCAD, Altium Designer etc. Since it helps prevent problems brought on by inconsistencies, PCB designers should tell their contract manufacturer prior to PCB manufacturing about the PCB design software version which is used to design the circuit board.
Designers export the final PCB design into a format that is supported by manufacturers once it is ready for manufacturing. Extended Gerber is the software that is most usually used.
Extended Gerber was developed by the PCB industry as the ideal output format. Gerber files, which all include detailed critical information like copper layers tracking, drill drawings, apertures, component notations, and other choices, may need various Gerber file generating methods depending on the PCB design program being used. At this stage, the PCB design is checked in every area. To guarantee that no flaws go unnoticed, the program runs oversight algorithms on the design. Designers also consider features like hole size, hole spacing, track width, trace and board edge spacing when evaluating a plan.
Stage 2: Film making
Designers generate PCB schematic files, and manufacturers do a DFM check before PCB printing starts. Circuit boards are printed by manufacturers using specialized plotters, which create photography films of the PCBs. The films will be used by the manufacturers to image the PCBs. It isn’t a typical laser jet printer, despite the fact that it uses laser technology. Plotters produce an extremely detailed film of the PCB board design using exceptionally fine printing technology.
The finished item is a board printed in black ink with a picture negative of the PCB. Black ink is used to depict the conductive copper components of the PCB for the inside layers of the PCB. The portions of non-conductive material are shown by the remaining clear area of the picture. The outer layers have the reverse pattern: transparent for copper and black for the etched-away portion. The film is automatically developed by the plotter and then safely kept to avoid any improper touch.
A black and separate transparent film sheet is applied to each layer of the PCB and solder mask. A two-layer PCB requires four sheets in total: two sheet is for the solder mask and other two sheets is for the layers. Importantly, every movie has to match every other movie exactly. Together, they lay out the alignment of the PCB.
Stage 3: printed copper path
It’s time to print the figure from the film onto copper foil after the films with the copper path figure were done being created.
This stage of manufacturing PCBs sets up the creation of actual PCB. Epoxy resin and glass fiber, often known as substrate material, make up the laminate board that is the foundation of the PCB. An suitable body for holding the copper that supports the PCB is laminate. The PCB’s foundation is made of robust, dust-resistant substrate material. Each side of the copper is already bonded. To disclose the pattern from the films, the copper is whittled away during the process.
The registration holes must be punched through out each film to ensure exact alignment. By changing the table that the film is set on, the hole becomes more precise. The hole is punched when the table’s minute adjustments result in the best possible match. In the following phase of the imaging process, the holes cab be fit for the registration pins.
A layer of light-sensitive film known as photo resist is then applied to the clean panel. The photo resist is made up of a coating of chemically photo reactive substances that become rigid after being exposed to ultraviolet light. This guarantees a perfect fit between the photo resist and the photo films. The films are held in place over the laminate panel by pins that fit over the films.
A UV light burst is directed towards the film and board in a line. The photo resist on the copper beneath becomes more rigid when light travels through the transparent portions of the film. The plotter’s black ink shields the parts that are not supposed to harden and are intended for removal from the light.
After the board has been prepared, any photo resist that hasn’t yet solidified is removed by washing it in an alkaline solution. Anything else on the surface is removed with a final pressure wash. Next, the board is dried.
When the product is finished, the copper parts that are supposed to stay in the final shape have resist adequately covering them. A technician checks the boards to make sure there are no mistakes at this point. The copper that will emerge in the completed PCB is indicated by all the resist that is currently present.
Only boards with more than two layers need complete this step. Drilling is omitted for straightforward two-layer boards. Boards with several layers involve extra processes.
Stage 4: Removing those extra copper
The board moves on to the following step, the removal of undesirable copper, once the photo resist has been removed and the hardened resist has covered the copper we want to preserve. A stronger chemical solution takes away the extra copper in the same manner that the alkaline solution eliminated the resist. The exposed copper is completely removed by the copper solvent solution bath. Under the layer of photo resist that has become more durable, the desirable copper is still completely shielded.
Copper boards vary greatly from one another. Some heavier boards call for longer exposure times and higher concentrations of copper solvent. As a side point, track spacing needs to be carefully considered when using heavier copper boards. Standard PCBs often use the same specifications.
The hardened resist covering the desired copper has to be washed off now that the undesirable copper has been removed using the solvent. This is accomplished via yet another solvent. Only the copper substrate required for the PCB remains, leaving the board to gleam.
Stage 5: Automatic Optical Inspection(AOI)
The layers need alignment punches once they are all clean and prepared to guarantee that they line up. The inner layers are aligned with the outer layers via the registration holes. The operator inserts the layers into an apparatus known as an optical punch, which enables precise correspondence to ensure that the registration holes are punched correctly.
Any mistakes that arise on the inner layers cannot be fixed after the layers are assembled. To verify that there are no faults at all, another machine does an automated optical examination of the panels. The model is the original Gerber design that the manufacturer got. The machine electronically compares the digital picture with the original Gerber file after scanning the layers using a laser sensor.
If the machine discovers a discrepancy, the comparison is shown to the technician on a monitor for evaluation. The layer advances to the PCB production’s final stages after passing inspection.
Stage 6: Bond and layer-up
The circuit board begins to take shape at this phase. The merger of all the various strata is pending. The layers just need to fuse together now that they are prepared and verified. The substrate must be joined with the outer layers. Layer-up and bonding are the two processes that make up the process.
Fiber glass sheets that have already been pre-impregnated with epoxy resin make up the outer layer material. The abbreviation for this is prepreg. The copper trace etchings on the original substrate are also covered with a thin copper foil on the top and bottom. Put them in a sandwich right now.
On a large, heavy steel table with metal clamps, the bonding is done. Layers fit into table-mounted pins with ease. To prevent moving during the alignment, everything needs to fit snugly.
A prepreg layer is first applied by a technician over the alignment basin. Before the copper sheet is applied, the substrate layer is positioned over the prepreg. The copper layer is topped with more prepreg sheets. The stack is completed with an aluminum foil and a copper press plate. It is now ready for pressing.
The bonding press computer automatically runs a program during the whole process. The computer controls how the stack is heated, when pressure is applied, and when the stack is allowed to cool at a predetermined rate.
After that, some unpacking takes place. The technician just has to unpack the multi-layer PCB product once all the layers have been molded together into a super sandwich of PCB splendor. The top pressure plate must be thrown away when the restraining pins are easily removed. The PCB goodness triumphs from within its protective covering of aluminum press plates. The outside layers of the PCB are still made of the copper foil that was used in the manufacturing.
Stage 7: Drill
Finally, the stack board is drilled with holes. Precision drill holes must be accurate in order for later-added components like leaded elements and copper-linking through holes to function properly. The holes are drilled to a hair’s width; a human hair is typically 150 microns wide, but the drill only reaches a diameter of 100 microns.
An x-ray finder detects the appropriate drill target sites in order to locate the drill targets. The stack is then secured for the subsequent set of more precise holes by drilling the appropriate registration holes.
To guarantee a clean bore is executed, the technician installs a board of buffer material beneath the drill target prior to drilling. When the drill exits, the exit-material prevents any needless ripping.
Every little movement of the drill is managed by a computer; it seems sense that a product that regulates how machines behave would rely on computers. The drilling file from the original design is used by the computer-driven device to determine the appropriate places to hole.
Air-driven spindles that rotate at 150,000 rpm are used in the drills. Drilling may seem to move quickly at this speed, but there are actually a lot of holes that need to be drilled. There are often far over 100 bore intact places on a PCB. Drilling takes time since each person needs their own unique moment with the drill. The vias and mechanical mounting holes for the PCB are afterwards housed in the holes. These components are finally fastened after plating.
After the drilling is finished, a profile tool is used to remove the extra copper that lines the manufacturing panel’s edges.
Stage 8: Copper Deposition
The panel then proceeds on to plating after drilling. Chemical deposition is used to fuse the several layers together in the procedure. The panel is thoroughly cleaned before going through many chemical treatments. A thin layer of copper, one millimeter thick, is chemically deposited onto the panel’s surface throughout the baths. The freshly bored holes receive the copper.
The fiber glass material that makes up the inside of the panel is merely exposed by the internal surface of the perforations prior to this process. The walls of the holes are totally covered, or plate, by the copper baths. In addition, a fresh copper coating is applied to the whole panel. The fact that the new holes are covered is crucial. The entire dipping, removal, and procession procedure is managed by computers.
Stage 9: Imaging the outer layer
In this phase, we picture the panel’s outer layers using a PCB design once more. To prevent impurities from adhering to the layer surface, we start by applying the layers in a sterile environment. Next, we apply a layer of photo resist to the panel. The prepared panel enters the room with the yellow walls. Photo resist is effected by UV radiation. UV levels present in yellow light wavelengths are insufficient to alter the photo resist.
To prevent misalignment with the panel, black ink transparencies are pinned into place. A generator shoots intense UV light into contact between the panel and stencil, hardening the photo resist. The unhardened resist, which was shielded by the black ink opacity, is then removed off the panel by a machine.
The procedure mirrors that of the inner layers in reverse. The outer plates are next examined to make sure all of the undesirable photo resist was eliminated during the earlier procedure.
Stage 10: Plating
We head back to the plating area. We electroplate the panel with a small coating of copper, just as we did in Step 8. The copper electro-plating is applied to the panel’s exposed areas from the outer layer photo resist stage. The panel often undergoes tin plating after the initial copper plating baths, allowing all of the copper that was left on the board to be removed to be removed. The copper-covered area of the panel is protected by the tin during the subsequent etching process. Copper foil that is not needed is removed from the panel by etching.
Stage 11: final Etching
At this point, the tin shields the desirable copper. The copper behind the remaining resist layer and the undesirable exposed copper are removed. Once more, chemical treatments are used to get rid of extra copper. In the meanwhile, the tin shields the pricey copper at this point. Now that the conducting spaces and connections have been constructed correctly.
Stage 12: Solder Mask
The panels are cleaned and coated with epoxy solder mask ink before the solder mask is placed to both sides of the board. A UV light burst is directed at the boards and travels through a solder mask photo film. The covered areas will be removed since they are still soft. The board is then placed in an oven to dry the solder mask.
Stage 13: Surface Finish
We chemically treat the PCB with gold or silver to increase its solderability. During this phase, certain PCBs additionally get hot air-leveled pads. The uniform pads are the product of the hot air leveling. Surface finish is produced as a result of the technique. INTOPCB can handle a variety of surface finishes according on the unique requirements of the customer.
Stage 14: Silkscreen
The nearly finished board has ink-jet printing applied to its surface to identify all significant PCB-related information. Finally, the PCB moves on to the last stage of coating and curing.
Stage 15: Electrical Test
A technician conducts electrical testing on the PCB as a final precaution. The automated process verifies the PCB’s usability and conformance to the original design. At INTOPCB, we provide Flying Probe Testing, an innovative method of electrical testing that makes use of moving probes to evaluate the electrical performance of each net on a bare circuit board.
Step 16: Profiling and V-Scoring
We are now at the final phase, cutting. The original panel is cut into many boards. Either a router or a v-groove are used as the main components of the technique. A v-groove cuts diagonal channels along both sides of the board, whereas a router leaves little tabs along the edges. The boards may simply come out of the panel in any direction.
why PCB manufacturing in green?
The solder mask is used to protect the copper circuits printed on the board’s fiber glass core from short circuits. It also prevents the board from getting damaged due to soldering errors.
There are various theories about why green is considered to be the traditional color of PCBs. Some of these include the army’s role in the development of the technology, the color of the resins used during the production of PCBs, and the industry convention held in the 1950s.
Does the PCB must be manufactured in green color?
PCBs do not have to be green, they can still feature various colors. These can be used to distinguish them from one another or to customize them. In addition to standard production, INTOPCB can also produce custom colours for corporate or individual applications.
what material are the pcb layer made of ?
Regardless of the type of board you choose, each of its components has the same basic foundation. This means that even though different types of PCBs have varying number of layers, they all have the same essential foundation.
Substrate layer
This type of board is usually made from fiberglass, which gives it its rigidity. However, some types of substrates are also made with epoxies, which do not provide the same durability.
Copper layer
A printed circuit board (PCB) is made from a copper layer that’s laminated using heat.
When we talk about the various layers of a printed circuit board (PCB), we’re referring to the number of copper layers that are on one side of the board. For instance, in a single-sided board, the conducting material will only be on one side of the board. In a double-sided board, the other side will be used to incorporate electronic components.
The copper layer thickness of a PCB will be determined by the power it needs to operate. For instance, if the board needs to operate at a high power level, then the copper layer will have a thicker level.
Solder mask layer
The solder mask layer is placed over the copper, which provides the green color of PCBs. It also insulates the copper and prevents it from coming in contact with other elements.
Silkscreen layer
The goal of the silkscreen layer is to make it easier for people to understand the various functions of LEDs and pins. It adds numbers, letters, and symbols to the board so that it can be easily understood by users.
How to reduce the cost of PCB manufacturing?
Reduce PCB complexity
One of the easiest ways to reduce the cost of PCBs is by optimizing the board component layout. Doing so will allow you to reduce the size and complexity of the board. However, be careful not to use complex forms and leave enough space between the elements.
Complex forms are also more expensive if they are irregular. It’s recommended to avoid internal cuts on the board, and manufacturers will typically bill a supplement for any additional cuts. Although engineers like the appearance of an original design, this feature doesn’t add anything to the finished product and is not perceived as a significant factor in the design process.
Perfect PCB thickness and size
The size and complexity of PCBs have a significant impact on the wiring process. If the board is small and complex, it can take a lot of time and effort to complete it, and it will also be expensive to have the same board in multiple operations. One of the most important factors to consider is reducing the size of the board to save space.
One of the most important factors to consider is the complexity of the board. If the board is large and complex, it can affect the price. Having a square or rectangular board will allow you to keep control over the design.
The higher the number of layers you choose, the higher the costs. The various types of holes that you select can also affect the board’s performance. If the board is thinner, you can save money by reducing the overall cost. However, if the board is still thick, you might have to use more holes. Before you start implementing a new strategy, it’s important that you talk to your supplier about the cost savings.
Proper holes
The easiest way to create large holes and pads is by using a machine that doesn’t require a lot of accuracy. On the other hand, smaller holes and pads require more delicate control, which can take longer to make and increase your costs.
Optimize PCB Layout
The optimal distribution of components on a panel is also a key factor that can affect the cost of production. For instance, if a panel is too tight, it can lead to costly adjust or need to manual solder, it would increases in price.
Correct via
Although penetration vias are cheaper than embedded holes, both of these types of holes can lead to additional costs. For high-frequency and complex boards, the number of vias and their type can affect the production costs.
The presence of vias, such as blind vias, buried vias, and microvias, in a circuit board can affect the cost of production. Generally speaking, the more vias there are, the more expensive it will be. To minimize the cost of bare PCBs, it’s important that you arrange the number of vias in a way that guarantees their functions.
Order quantity
If you usually order 10 times one, each time order 200 pieces. You can change to order 5 times, each time order 400 pieces, order more quantity usually average cost can be cheaper, and each item shipping would be cheaper too. That can you to save cost.
Shape
The price of PCBs can also be affected by the shape of the PCB. For instance, if a square or rectangle is used, it will lead to low prices while special shapes will increase the cost.
Surface finish
A surface finish is a type of protective coating that can prevent pads from oxidizing. There are various types of surface finishes that can be used, such as OSP, ENIG, and HASH. They have advantages and disadvantages, and they can be chosen the best fit for your products depending on your requirements.
Got a professional suggestion
Before the end of the engineering design phase, it’s important that you have a dialogue with your PCB manufacturer to discuss the various aspects of your project. This can help you identify the potential issues that could affect your project.
Before you start the design process, it’s important that you gather as much information as possible about your suppliers. This will allow you to make informed decisions and minimize the time that you spend on the project. Doing so will allow you to avoid costly errors and ensure that the right solution is available to you.
We an professional PCB manufacturer serve in PCB fabrication industry since 2000. No matter you need single sided PCB, double sided PCB, or multilayer PCB, we all can make for you. If you contact us, we can give you some suggestions for free.
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