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PCB Manufacturing – A Complete Guide for Beginners
Today's electronics heavily rely on PCB (Printed Circuit Boards.) PCBs are essential elements that help transmit electrical signals to fulfill the device's mechanical and electrical functions. Therefore, PCB design and manufacturing process is necessary for anyone in the electronic world.
However, the PCB manufacturing process is a complex procedure that involves several crucial steps. Hence, skipping any step can negatively affect the circuit board's performance. To help you understand the PCB design and manufacturing process below is a complete guide for beginners.
However, the PCB manufacturing process is a complex procedure that involves several crucial steps. Hence, skipping any step can negatively affect the circuit board's performance. To help you understand the PCB design and manufacturing process below is a complete guide for beginners.
How are Printed Circuit Boards manufactured?
Step 1: Designing and Printing the PCB
The first step of PCB manufacturing is design and printing. The designer comes out with an outline for the PCB that fulfills all the requirements as defined. Luckily, there are several design programs used by the designers.
After inspection, the design goes back to a PCB fabrication house. Here, it undergoes another check referred to as the Design for Manufacture (DFM) check. The check is to ensure PCB design fulfills the requirements needed for manufacture. Once the checks are done, the design is printed using a plotter printer.
The first step of PCB manufacturing is design and printing. The designer comes out with an outline for the PCB that fulfills all the requirements as defined. Luckily, there are several design programs used by the designers.
After inspection, the design goes back to a PCB fabrication house. Here, it undergoes another check referred to as the Design for Manufacture (DFM) check. The check is to ensure PCB design fulfills the requirements needed for manufacture. Once the checks are done, the design is printed using a plotter printer.
Step 2: Printing of the copper for the inner layers
This is the first step where manufacturing a printed circuit board starts. PCB design is printed onto a laminate material, and then copper is pre-bonded to the same laminate. It serves as the structure for the printed circuit board.
Later, the laminate panel is shielded by a photo-sensitive film known as a resist. The work of the resist is to help technicians get a match between photos of the blueprint and what is printed to the photoresist.
When the resists and the laminate are lined up, they get a blast of UV light. The UV light passes through the translucent areas of the film, toughening the photoresist. This shows areas of copper meant to be pathways, while the black ink prevents light from getting to parts that should not be hardened to be removed later.
This is the first step where manufacturing a printed circuit board starts. PCB design is printed onto a laminate material, and then copper is pre-bonded to the same laminate. It serves as the structure for the printed circuit board.
Later, the laminate panel is shielded by a photo-sensitive film known as a resist. The work of the resist is to help technicians get a match between photos of the blueprint and what is printed to the photoresist.
When the resists and the laminate are lined up, they get a blast of UV light. The UV light passes through the translucent areas of the film, toughening the photoresist. This shows areas of copper meant to be pathways, while the black ink prevents light from getting to parts that should not be hardened to be removed later.
3. Removing unneeded copper
Before the PCB fabrication process can continue, the unneeded copper needs to be removed; hence, the next step is to remove unwanted copper. The board goes through a powerful chemical to get rid of copper that is not covered by the photoresist.
Once the unneeded copper is removed, the hardened photoresist also needs to be removed. This will ensure only the required copper for PCB is left.
Before the PCB fabrication process can continue, the unneeded copper needs to be removed; hence, the next step is to remove unwanted copper. The board goes through a powerful chemical to get rid of copper that is not covered by the photoresist.
Once the unneeded copper is removed, the hardened photoresist also needs to be removed. This will ensure only the required copper for PCB is left.
4. Inspection and Layer Alignment
Once the cleaning is done, the PCB needs to go through alignment and inspection. This is a crucial step that ensures the board meets the needed requirements. They need to go through a punch machine known as an optical punch to align the layers.
Optical punch work is to drive a pin through the holes to ensure the PCB layers are in line. Also, another machine is used to perform an optical inspection. This is to make sure there are no defects.
Optical inspection is vital because there is no chance of changing the errors once the layers are fixed together.
Once the cleaning is done, the PCB needs to go through alignment and inspection. This is a crucial step that ensures the board meets the needed requirements. They need to go through a punch machine known as an optical punch to align the layers.
Optical punch work is to drive a pin through the holes to ensure the PCB layers are in line. Also, another machine is used to perform an optical inspection. This is to make sure there are no defects.
Optical inspection is vital because there is no chance of changing the errors once the layers are fixed together.
5. Laminating the Printed Circuit Board Layers
Now the PCB layers are ready to be laminated. However, the laminating of the printed circuit board layers happens in two stages. There is the lay-up stage and laminating stage.
i) Lay-up Stage
This is a critical step where a layer of epoxy resin and a layer of copper foil covers both the inner and outer layers of the PCB. And once they are ready, they are sandwiched using metal clamps on a press table.
ii) Laminating stage
This is another essential step where the technician places a layer of epoxy resin called prepreg on the alignment basin. Then a layer of substrate covers the prepreg resin, followed by a layer of copper foil.
After these processes, the layers go through a laminating press of melting the epoxy inside the prepreg, heating the laminating plates, and the pressure from the press to fuse the stack of the PCB layers.
Now the PCB layers are ready to be laminated. However, the laminating of the printed circuit board layers happens in two stages. There is the lay-up stage and laminating stage.
i) Lay-up Stage
This is a critical step where a layer of epoxy resin and a layer of copper foil covers both the inner and outer layers of the PCB. And once they are ready, they are sandwiched using metal clamps on a press table.
ii) Laminating stage
This is another essential step where the technician places a layer of epoxy resin called prepreg on the alignment basin. Then a layer of substrate covers the prepreg resin, followed by a layer of copper foil.
After these processes, the layers go through a laminating press of melting the epoxy inside the prepreg, heating the laminating plates, and the pressure from the press to fuse the stack of the PCB layers.
6. Drilling
The next step of PCB manufacturing is drilling. This is where a technician drills the guiding holes with a drill machine. This is to ensure the PCB is secure before more particular holes are drilled.
In this process, CNC milling and drilling are the most used methods. When drilling the holes, a CNC drilling machine is used. But you need to use a file from Extended-Gerber design as your guide. After the drilling is done, extra copper from the board's edges is filed off.
The next step of PCB manufacturing is drilling. This is where a technician drills the guiding holes with a drill machine. This is to ensure the PCB is secure before more particular holes are drilled.
In this process, CNC milling and drilling are the most used methods. When drilling the holes, a CNC drilling machine is used. But you need to use a file from Extended-Gerber design as your guide. After the drilling is done, extra copper from the board's edges is filed off.
7. PCB Plating
After the drilling stage, the board is ready for plating. In this process, a chemical is used to fuse different board layers. Once the PCB is cleaned, it is bathed in a sequence of chemicals.
One part of the bathing procedure is to cover the panel in a heavy layer of copper that deposits over the top-most layers of the drilled holes.
After the drilling stage, the board is ready for plating. In this process, a chemical is used to fuse different board layers. Once the PCB is cleaned, it is bathed in a sequence of chemicals.
One part of the bathing procedure is to cover the panel in a heavy layer of copper that deposits over the top-most layers of the drilled holes.
8. Outer Layer Imagining and Plating
This is a step where another layer of photoresist is applied. But at this phase, the photoresist is only used on the outer layer, and then it goes through imaging. Also, it goes through the plating procedure as the interior layers of the board were done in the previous step.
This is a step where another layer of photoresist is applied. But at this phase, the photoresist is only used on the outer layer, and then it goes through imaging. Also, it goes through the plating procedure as the interior layers of the board were done in the previous step.
9. The last Etch
Here, the outer layer of the board goes through the last etch. There is a tin guard to protect copper throughout the etching process. So, after removing the undesirable copper and establishing all PCB connections.
Here, the outer layer of the board goes through the last etch. There is a tin guard to protect copper throughout the etching process. So, after removing the undesirable copper and establishing all PCB connections.
10. Solder Mask
During this step, an ink epoxy and a solder mask are used to cover the board. Then the PCB goes through a UV ray exposure that helps to mark out a particular solder mask for removal.
During this step, an ink epoxy and a solder mask are used to cover the board. Then the PCB goes through a UV ray exposure that helps to mark out a particular solder mask for removal.
11. Finishing and Silk Screening
During the finishing process, the boards are plated with silver, gold, or HASL so that the components are ready to be soldered to the pads to protect the copper. In the silk screening, vital information is printed on the board. This information includes company ID numbers, manufacturer marks, and warning labels.
During the finishing process, the boards are plated with silver, gold, or HASL so that the components are ready to be soldered to the pads to protect the copper. In the silk screening, vital information is printed on the board. This information includes company ID numbers, manufacturer marks, and warning labels.
12. Functional Reliability Testing
Here, the PCB goes through a set of electrical and functional tests. But the basic tests performed are the continuity and isolation tests. Even though electrical tests ensure functionality, they also test whether the PCB followed the manufacturing process.
Then the PCB board goes through another inspection phase. General cleanliness is conducted to ensure there are no sharp edges or any manufacturing hazards at this stage. Also, checks for chamfers, slots, bevels, and others are done according to client specifications.
Here, the PCB goes through a set of electrical and functional tests. But the basic tests performed are the continuity and isolation tests. Even though electrical tests ensure functionality, they also test whether the PCB followed the manufacturing process.
Then the PCB board goes through another inspection phase. General cleanliness is conducted to ensure there are no sharp edges or any manufacturing hazards at this stage. Also, checks for chamfers, slots, bevels, and others are done according to client specifications.
