A Quick guide on the manufacturing of Printed circuits
“Printed circuits are the future of electronics.” This statement is considered to be a cliché by most of the tech critics as they believe technology is advancing day-by-day. But this advancement has to be in circuits. Why?
Well, circuits are the most essential part of any device. The ‘brain’ and ‘heart’ in a human vessel has never been changed not even by the creator nor by humans themselves. Similarly, the printed circuits (‘brain’ off a device) can be developed but not changed until the tech-geeks find another power source. Printed circuit boards are an invention that can be observed in almost all the electronic devices. Its basic function is to connect the components of the device and transmit electric power to them. It also provides an area for the surface-clamped wires.
Hence, we can say that like brain PCB tells blood (here electricity) its path, on which it sshoukd flow to reach the organs (here circuit components). It sends current via a set of connections consisting copper pathways around its body (circuit). Yet, to manufacture a PCB a designer has to visit the fabrication industry first and inquire about the requirements for the PCB’s manufacturing. This is the reason behind the outsourcing for manufacturing of PCBs as companies want minimal errors and maxed-up efficiency.
Below is a perfect guide to help the PCB designers to get over the errors and design an efficient printed circuit board.
Steps that will lead to designing of an efficient PCB:
STEP-1 Designing and output estimation
The primary thing in this designing section is the software on which the design has been made. It is recommended for the designers to inform the manufacturer about the version of the software so that it might not get complicated when the manufacturing starts. Various designing software for designing a PCB are: CAD, KiCad, Altium designer, Pads, Eagle and so on…
After the design has been approved for reaching the production stage, the designer must convert the file into a format that the designer supports. Here, Gerber can be used as it’s the most prominent product in the market. It is also known as IX274X.
Important information like drill drawing, component notations, copper tracking the layers, apertures etc, are encoded with the help of the Gerber. Hence, IX274X has been considered as the best output format. The software uses algorithms to counter check every aspect of the design and so, leaves no error. Here, another inspection is carried out by the designer that goes by the name of design for manufacturing as it tests all the tolerances that it should have before it undergoes the Manufacturing process.
STEP-2 When Files are replaced by Films!
The schematic files made by the designers are replaced by the ‘negatives’ (conventional photography films). These films are used by manufacturers when they print the circuit board’s design using a ‘plotter’- a laser printer. These designs on films are used to image the printed circuit on the copper board. The technology of a plotter makes it efficient enough to provide a properly detailed design, the way it was on the software.
A sheet with the negatives on it in black is obtained from the plotter. In this design, the inked part represents the copper parts of the printed circuits. The clear patches on the plastic sheet represent the non-conductive parts of the circuit board. The area other than the copper’s conductive part will be removed. The sheets are used for the circuit board’s surface and solder masks. Hence, for designing a two layer PCB, four sheets are required.
The sheets should stick along the circuit’s body in such a manner that it should not disobey the alignment pattern. However, to give the sheets a perfect alignment you must create the connection holes in a manner that they face each other accurately else the circuit’s alignment will be disintegrated.
STEP-3 Creation of the printed layers on the copper surface
This is the initial stage of the creation of a PCB. The printed circuits are inscribed on a copper plate. It’s time to start the making of that copper plate actually. The board is made of substrate materials which are epoxy resin and glass fiber. The board is laminated in order to hold the copper over its surface. The substrates provide stiffness to the circuit board as well as make the board’s body a dust-resistance one. Copper is coated on both sides of the circuit board. To stop the circuit from being short or open it is decontaminated and cleaned so that no dust particle remains on the copper coated board.
It also consists of a layer that has photo chemicals over it. Now, that is what the photo films we created in the previous step require to settle on the copper board. The copper-coated board and the photo film are sandwiched on both sides. The sandwich undergoes an interaction with the UV light. The UV light here, hardens the photo film on the copper layer making them one. The ink markings from plotters prevent the UV rays from reaching the circuits structure areas.
The alkaline solution and a pressure wash are used to clean the board after which it’s left to dry. This step is used while manufacturing PCBs with more than two layers. In simple PCB manufacturing process, after the second step the manufacturer switches directly to the drilling part.
In manufacturing of multiple-layer PCBs some steps are executed before drilling:
• Copper removal
• Layer alignment
• Optical inspection
• Layer bonding
STEP-4 Drilling of the circuit holes!
A computer-controlled drill is used to create holes in the printed circuit board. The speed of the drill is approximately 150,000 rpm, well, at this speed a hole is drilled within a second. But, an average PCB consists of a hundred holes to drill thus, it takes time to drill them with precision even for a machine for it has to follow a certain path to drill all those holes.
STEP-5 Copper deposition and plating
This step is also the one that is used while creating a multi-layer PCB. This step involves the diffusion of different copper plated layers using chemical deposition.
STEP-6 Layer Imaging
After the drilling and plating the most important step in the manufacturing process comes. The photo film is deposited again. Now it contains the PCB’s design on it. This process is performed in sterile environment in order to make the PCB board perfect.
This step involves a repetition of the step before the previous step. Hence, it is also useful while manufacturing a multi-layer PCB.
The tin plating done in the previous step protects the copper while etching. As in this step as well copper is scrapped from the surface where it is excessive. The chemical solutions are applied once again to sterile the board and maintain its clean surface.
After etching connections are made over the conducting surface.
STEP-9 Solder mask
By using an epoxy solder mask ink, solder masks are established over the surface of the copper board. The UV lights are allowed to pass through the board again so that the photo film bonds with the board.
It then is passed to the oven to heat.
A plating of gold or silver is done on the circuit board which provides it a properly finished surface. Hot air-leveling is done to give the PCBs a proper surface finish.
STEP-11 Electrical Testing
A technician is employed for this step. The work of the technician here is to perform electrical endurance, durability, flow and resistance tests on the printed circuits. The results of this electrical testing will tell the exactness of the printed circuit board with the prepared design.
Designing a Printed circuit is not that big of a deal but manufacturing is. So, to get a PCB manufactured you must know the best PCB manufacturers in Canada and also the ways to select the best PCB manufacturer in Canada. This article covered most of the details required by a person to manufacture a PCB with some research. There are some steps in the article which are the most important ones as they are to be followed lest you are ready for a circuit failure!