WHAT IS PCB?
A printed circuit board mechanically supports and electrically connects electronic components using conductive tracks, pads and other features etched from one or more sheet layers of copper laminated onto and/or between sheet layers of a non-conductive substrate.
MANUFACTURING PROCESS
Board cutting
The process starts with board cutting. First, the board is dry cleaned in a machine and then cut and small pieces which is suitable for manufacturing.
Drilling
After cutting they come to the drilling room. Drilling is done for two purposes for connecting the loaded components and for the via holes that link the copper layers together first the operator takes an MDF board as exit material then they load one or more PC panels and place it on the machine and finally adds the sheet of aluminium as an entry foil. Those machines are computed-controlled after selecting the right drill program the machine starts working drill change is fully automatic. The machine selects the drill to use from the drill rack and checks that it is the correct size and then loads it into the drill head this is a year driven drill that can rotate up to 150 revolutions per minute. The high-speed drill makes the whole wall cleaner after that the corners are trimmed to make it round it. Then the surface is clean the machine automatically smooths the edges of the board one side at a time as the board has drilled for making the connection between top and bottom there but in the middle there is non-conductive fibreglass. So, to make a connection between top and bottom there the board comes for electroplating the operator loads the panels onto the flight bars the panels themselves act as cathodes for electroplating the panels are carried through a series of chemical and rinsing baths by the overhead crane. This is a multi-stage process, and everything is controlled by a computer to ensure about one-micron thick copper has deposited over the walls of the hole.
Copper plating
After that, the board goes through a series of processes where copper is plated up to a thickness depending on the required. The final finish for the panel this process took about 40 minutes and then the board automatically goes to another room for the next step. To enter into this room, we need to put on a special type of anti-static clothes and we need to pass through a dust cleaning chamber.
Image the outer layers
Then it is first coated with a layer of photosensitive film in the photoresist which is hot rolled onto the copper. This machine does this automatically or sometimes down this process manually. This film is blue light-sensitive so all the lights in the room are yellow, so the light does not affect this film then the operator cleans the films. The film is the one that already has printed circuit diagrams on it and loaded the first pill. Then put the laminated panel and finally the second theory after perfectly aligning both layers the board is sent to the printer. So, after this process, only the circuit part is hardened and the rest unwanted areas remain soft. A modern machine can do this whole process automatically. Next, the board is processed through a chemical solution or developer that removes the unhardened and unwanted resist from areas that were not polymerized by light.
Etching
This process is to remove the unwanted copper using a powerful alkaline solution. After etching, the boards need to be cleaned and washed to remove the excess chemical solution then the boards come for automatic optical inspection or AOI.
AOI (Automatic Optical Inspection)
This machine enables a fast and accurate section of PCBs to ensure that the quality of product leaving the production line is high and the items are built correctly and without manufacturing faults. When detecting circuits the machine automatically scans the PCB through the camera collects images and compares the tested solder joints with the qualified parameters in the database. When everything is okay, the board comes again to another yellow for solder mask.
Solder mask
This coating machine simultaneously covers both sides of the panel with a boxes solder masking. A solder mask is required to protect the copper surface and prevents older short in between components during assembly. After applying solder mask, panels are now wrecked and put through a conveyance to the dryer at 87 degrees Celsius, which hardens the resist just enough for the next stage.
Residual solder pad
Usually, it takes almost 25 minutes to bake a solder mask is applied all over the board to remove the solder mask from the solder pad. First, the operator takes the PCB and then align the photo film carefully at both sides simultaneously. The UV lamp in the machine hardened the ink where the film is a clear letter on the unhardened and unwanted resists are stripped off. Most PCBs have a component legend to show which component goes where they use in jet printers to image the legends direct from the board digital data.
Legend/silkscreen
This printer is very advanced the operator only needs to find the silkscreen file corresponding to the board and set the positioning on the main control computer. Then the inker will be applied on the boards evenly and automatically. Moreover, it can also be printed and cured on the same system to protect the copper of solder pad from oxidation hot-air solder levelling is often chosen as surface finish method for circuit boards. In addition to the usual HASL, they also provide a variety of surface treatment methods such as Immersion gold, Hard gold and OSP for customers to choose according to their needs. Finally, the PCB production process is done then they are electrically tested.
Testing
Every multi-layer PCB against the original board data using flying probe tester that is the high voltage insulation and low resistance conduction of the circuit boards and check each net to ensure that the circuit is complete and there is no short or open circuit for high-volume production. They use an automatic test machine which saves time and money because it runs at a high rate after all testing the boards come into the milling room.
Milling & v-scoring
Now it’s time to separate all individual PCBs from the large production panel. The operator loads one or more PCBs onto the CNC machine and chooses the right program for those ports. According to customer needs the board or array can also be stored so that they can be easily broken apart after assembly after milling the board comes for cleaning.
Board washing
This machine cleans dust and oil stains using ultrasonic waves after wet cleaning the boards are dried.
Final inspection
Then a team of sharp-eyed inspectors give each PCB a final and carefully check over they look for any cosmetic defects like scratches and marking also check aperture, thickness, holes. etc. After inspection, the PCBs are vacuum sealed, and bubble wrapped to keep out dirt and moisture.
Packaging
Then the packets come to the packing room after printing the production release note PCBs are securely boxed inside the form wrapper and at the end of the day, the courier comes and takes a package and delivers it all over the world.
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DISCLAIMER
The information is provided by Tecquisition for general informational and educational purposes only and is not a substitute for professional legal advice. If you have any feedback, comments, requests for technical support or other inquiries, please mail us at tecqusition@gmail.com.
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