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custom pcb cost fabrication

Basic Info

Model No.: Quickturn printed circuit board production

Product Description

What is PCB manufacturing process?

PCB manufacturing process steps
Step 1: Design and output
The circuit boards should be strictly compatible, and the designer creates a PCB layout using PCB design software. Note: Before PCB manufacturing, designers should inform their contract manufacturers about the PCB design software version used to design the circuit, which helps to avoid problems caused by differences.
Once the PCB design is approved for production, the designer will export the design to a format supported by its manufacturer. The most commonly used program is called Extended Gerber.
After a comprehensive inspection, the designer forwards the PCB file to custom pcb fabrication. In order to ensure that the design meets the minimum tolerance requirements in the manufacturing process, almost all PCB Fab Houses conduct a design for manufacturing (DFM) inspection before the circuit board is manufactured.
Step 2: From file to film.
After the designer outputs the PCB schematic file and the manufacturer, the PCB printing begins to perform DFM inspection. The manufacturer uses a special printer called a plotter to make the photo film of the PCB to print the circuit board. Manufacturers will use these films to image PCBs. Although it is a laser printer, it is not a standard laser inkjet printer. The plotter uses incredibly precise printing technology to provide highly detailed PCB design films.
The final product resulted in the use of black ink on PCB negative photographs of the plastic. For the inner layer of the PCB, the black ink represents the conductive copper part of the PCB. The remaining transparent parts of the image represent areas of non-conductive material. The outer layer uses the opposite pattern: the copper color is clear, and the black refers to the area that has been etched away. The plotter automatically develops the film, and the film is stored safely to prevent any unnecessary contact.
Each layer of PCB and solder mask has its own transparent and black film. In general, a two-layer PCB requires four pieces: two layers for layers and two pieces for solder mask. It is worth noting that all lines must correspond perfectly to each other.
Step 3: Print the inner layer: Where is the copper wire?
The film creation in the previous step aims to draw the figure of the copper path. Now it is time to print the graphics on the film onto the copper foil.
This step in PCB manufacturing prepares the actual PCB. The basic form of PCB includes laminate, whose core material is epoxy resin and glass fiber, also known as substrate material. The laminate is an ideal body for receiving the copper that makes up the PCB. The substrate material provides a strong and dust-proof starting point for the PCB. The copper is pre-bonded on both sides. This process involves cutting copper to reveal the design of the film.
In the PCB structure, cleanliness is very important. Clean the copper side laminate and pass it into a decontaminated environment. At this stage, it is important that no dust particles are deposited on the laminate. Wrong dirt may cause the circuit to short-circuit or remain open.
Next, the cleaning panel receives a layer of photosensitive film called photoresist. The photoresist includes a layer of photoreactive chemical substance that hardens after exposure to ultraviolet light. This ensures precise matching from photographic film to photoresist. These films are attached to the pins, fixing them to the laminate.
The film and the circuit board line up and receive ultraviolet rays. The light passes through the transparent part of the film and hardens the photoresist on the copper underneath. The black ink from the plotter prevents light from reaching areas that should not be hardened, and they can be removed.
After the circuit board was prepared, any photoresist was not hardened by cleaning with an alkaline solution. The final pressure wash removes anything else left on the surface. The board is then dried.
When the product appears, the resist covers the copper area appropriately to maintain the final form. The technician checks the circuit board to ensure that no errors occur at this stage. All resists present at this time represent the copper that will appear in the finished PCB.
This step is only applicable to circuit boards with more than two layers. Simple double-layer boards can be drilled directly. Multilayer boards require more steps.
Step 4: Remove unwanted copper
With the photoresist removed and the hardened resist covering the copper we wish to retain, the circuit board enters the next stage: unwanted copper removal. Just like alkaline solutions to remove resists, more powerful chemicals will eliminate excess copper. The copper solvent solution bath removes all exposed copper. At the same time, the required copper remains fully protected under the hardened layer of photoresist.
Not all copper plates are the same. Some heavier boards require larger amounts of copper solvent and different exposure times. In addition, heavier copper plates require additional attention to track spacing. Most standard PCBs rely on similar specifications.
Now that the solvent removes the unwanted copper, the hardened resist protecting the preferably copper needs to be washed off. Another solvent accomplishes this task. The circuit board now only flashes the copper substrate required by the PCB.
Step 5: Layer alignment and optical inspection
When all the layers are clean and ready, the layers need to be aligned and punched to ensure they are all aligned. The alignment holes align the inner layer with the outer layer. The technician puts these layers into a machine called an optical punch, so that they can correspond accurately and punch accurately.
Once the layers are put together, it is impossible to correct any errors that occur in the inner layer. Another machine performs an automatic optical inspection of the panel to confirm that it is completely free of defects. The original Gerber design received by the manufacturer serves as a model. The machine uses a laser sensor to scan the layers and continues to electronically compare the digital image with the original Gerber file.
If the machine finds inconsistencies, the comparison is displayed on the display for the technician to evaluate. Once the layer passes the inspection, it will enter the final stage of PCB production.
Step 6: Layering and bonding
At this stage, the circuit board takes shape. All the individual layers await their union. As the layers are prepared and confirmed, they just need to be fused together. The outer layer must be connected to the substrate. The process is carried out in two steps: delamination and bonding.
The outer layer material consists of glass fiber board impregnated with epoxy resin in advance. This abbreviation is called prepreg. The thin copper foil also covers the top and bottom of the original substrate, which contains copper trace etching. Now, it's time to clip them together.
The bonding takes place on a heavy steel table with metal clips. These layers are firmly fitted on the pins attached to the table. Everything must fit together to prevent shifting during the alignment process.
The technician first puts the prepreg layer on the alignment groove. Before placing the copper plate, the base layer is attached to the prepreg. Another prepreg is on top of the copper layer. Finally, the aluminum foil and the copper press plate are stacked. Now it is ready to be pressed.
The entire operation is run through the automatic program of the bonding press. The computer coordinates the process of heating the stack, the point at which pressure is applied, and when to allow the stack to cool at a controlled rate.
Next, a certain amount of unpacking occurs. All layers are molded with Super Sandwich PCB, and technicians only need to open the packaging of the multilayer PCB product. It is a simple matter to remove the restriction pin and discard the top pressure plate. The goodness of the PCB wins out from the aluminum press plate housing. The copper foil included in the process still contains the outer layer of the PCB.

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Step 7: Drilling
Finally, drill holes in the stacking board. All subsequent components, such as copper connections through holes and leads, rely on the precision of precision drilling. The width of the drilled hair is-the diameter of the drill is 100 microns, and the average hair is 150 microns.
To find the location of the drilling target, the X-ray locator can identify the correct drilling target point. Then, appropriate positioning holes are drilled to secure a stack of a series of more specific holes.
The computer controls every micro-movement of the drill-it is natural that products that determine the behavior of the machine depend on the computer. The computer-driven machine uses the originally designed drill file to identify the proper location for the drill.
The drill uses a pneumatic shaft with a speed of 150,000 rpm. At this speed, you might think that drilling occurs in an instant, but there are many holes that need to be drilled. The average PCB contains more than 100 complete holes. During the drilling process, each drill bit needs its own special moment, so it takes time. These holes later accommodate PCB via holes and mechanical mounting holes. After electroplating, the final bonding of these parts will be done later.
After the drilling is completed, the extra copper lined up on the edge of the production panel is removed by analysis tools.
Step 8: Electroplating and copper deposition
After drilling, the panel is moved to electroplating. This process uses chemical deposition to fuse the different layers together. After thorough cleaning, the panel goes through a series of chemical baths. In the bath, the chemical deposition process deposits a thin layer of copper on the surface of the panel-about 1 micron thick. Copper enters the most recently drilled hole.
Before this step, the inner surface of the hole exposes only the glass fiber material constituting the inside of the panel. The copper bath completely covers or plated the hole wall.
Step 9: Outer layer imaging
In step 3, we apply photoresist to the panel. In this step, we do it again-except this time, we use the PCB design to image the outer layer of the panel. We start with the layer in the sterile room to prevent any contaminants from adhering to the surface of the layer, and then apply a layer of photoresist on the panel. The prepared panel enters the yellow room. UV lamps affect photoresist. The ultraviolet level of the yellow wavelength is not enough to affect the photoresist.
The black ink transparencies are fixed by pins to prevent misalignment with the panel. With the panel and template in contact, the generator irradiates them with high UV light, which hardens the photoresist. The panel then enters a machine to remove the unhardened resist, protected by the opacity of the black ink.
The process is opposite to the reversal of the inner layer. Finally, the outer board is checked to ensure that all unnecessary photoresist is removed in the previous stage.

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Step 10: Electroplating
We return to the electroplating room. As we did in step 8, we electroplated the panel with a thin layer of copper. The exposed part of the panel from the outer photoresist stage receives copper electroplating. After the initial copper plating bath, the panel usually receives tin plating, which allows all the copper remaining on the board to be removed for removal. In the next etching stage, tin protection of the panel means keeping the copper covered. Etching removes unnecessary copper foil from the panel.
Step 11: Final etching
Tin protects the required copper at this stage. The unwanted exposed copper and copper under the remaining resist layer undergoes removal. Again, a chemical solution is applied to remove excess copper. At the same time, tin protects valuable copper at this stage.
The conductive areas and connections are now correctly established.
Step 12: Solder mask application
Before applying the solder mask to both sides of the circuit board, clean the panel and cover it with epoxy solder resist ink. The circuit board receives ultraviolet rays and passes through the solder mask to the photographic film. The covered part remains unhardened and will be removed.
Finally, the circuit board enters the oven to cure the solder mask.
Step 13: Surface treatment
In order to add extra soldering capacity to the PCB, we electrolessly plate them with gold or silver. At this stage, some PCBs can also receive hot air flat pads. Hot air leveling results in an even pad. This process results in a surface finish. PCBCart can handle many types of surface treatments according to the specific requirements of customers.
Step 14: Screen printing
The nearly completed circuit board receives inkjet writing on its surface to indicate all important information related to the PCB. PCB finally enters the final coating and curing stage.
Step 15: Electrical test
As a last precaution, technicians conduct electrical tests on the PCB. The automated procedure confirms the function of the PCB and its consistency with the original design. At PCBCart, we provide an advanced electrical test called flying probe test, which relies on moving probes to test the electrical performance of each network on the bare circuit board.
Step 16: Analysis and V-Scoring
Now we come to the final step: cutting. Cut out different boards from the original panel. The method used is centered on the use of routers or V-grooves. The router leaves small tabs along the edge of the board, while the V-shaped groove cuts diagonal channels along both sides of the board. Both methods allow the circuit board to be easily ejected from the panel.

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