When we talk about the manufacturing or production of a Printed Circuit Board (PCB), we are referring to two things. The first is the fabrication of the board, which has to do with the process of transferring the schematic design to the bare board. It is after this that the circuit can be subjected to prototyping (if the customer needs this). Otherwise, the designer would immediately commence the next production stage of placing the needed components on the board vias a process called Printed Circuit Board Assembly (PCBA).
In this article, we walk you through the process of manufacturing your PCB electronics.
What Goes into PCB Manufacturing?
A lot of processes go into the production of circuit boards. It could range from 10 and 20, depending on what you want to achieve.
However, we have listed and explained some of the most important processes below:
1. Schematic Design Creation
This is usually the first step. The creation of the schematic design entails the production of the early-stage design for the PCB, which would serve as a guide for the next stages of production.
It is expedient to mention that the schematic design needs to be done with the best tools, such as Eagle, Altium Designer, KiCAD, OrCAD and Pads.
It is after the design has been made that you can contact a PCB manufacturing company to act upon it and start designing.
You must also note that there might be issues arising from the schematics and it often happens when you don’t communicate with the designer ahead of time. The reason for doing this is to inform the designer of the design expectations, as well as the PCB schematic design tool/software used for the design.
2. Circuit Board Fabrication
A lot of steps go into fabricating the board ahead of the component placement (assembly). Here are some of the things you need to know about this stage of PCB electronics manufacturing:
- Circuit Board Printing: this has to do with the transfer or transcribing of the PCB (schematic) design onto the bare board – the physical structure of the circuit board. For this process, a set of steps, including the making of “photo films” of the PCB, and the punching of “registration holes” through the films as a way of perfecting the alignment of the films.
- Inner Layers’ Printing: the inner layer of the PCB will now be printed or have the mapped-out figure of the copper path unto the copper foil. The “unwanted” or unused copper is removed, after the photo resist has been removed. The unwanted copper’s removal process often involves washing the surface with a copper solvent solution bath.
3. PCB Optical Inspection
This is an important step to be taken to ensure that the board doesn’t suffer defects later on. The optical inspection has to do with the alignment of the inner layers to the outer layers. The idea is to ensure that the registration holes are accurately punctured.
The accurate puncturing of the holes, and the conduction of optical inspection on the circuit panels helps to validate the PCB’s free of errors.
4. Layer-Up and Bonding Process
At this stage, we are looking at the fusion or connection of the necessary layers on the Printed Circuit Board (PCB). For emphasis, the outer layers must be connected to the substrate.
The next step is to bond or sandwich the original substrate’s top and bottom (that contains the copper trace etchings), and the outer layer material consisting of the sheets of fiberglass, which, in turn, is impregnated with epoxy resin.
5. Hole Drilling
With the bonding processes completed, holes will now be bored or drilled into the PCB’s stack. The hole-drilling process takes time and once it is completed, you can be sure that the mechanical mounting holes and the vias for the PCB have been drilled.
6. Chemical Deposition
Actually, two processes take place here. They are plating and chemical deposition. Plating has to do with the subjecting of the panel for a thorough cleaning. It is after this has been done that the panel can be subjected to a series of chemical baths, during which the chemical deposition process will be used to deposit or place a thin layer of copper over the panel’s surface.
7. Outer Layer Imaging and Plating
It is now the time of the outer or exterior PCB layer to be imaged. The process includes the application of photo resist to the panel, the removal of the unhardened resist on the panel and the inspection of the outer plates. The inspection is required to validate the total removal of the unhardened resist.
Once this has been done, the plating process will be brought back. It involves the electroplating of the panel using a thin layer of copper. Tin plating is also used here to remove the copper left on the board.
Once these have all been done, we can then move to the next stage of etching the board.
8. Copper Etching
The etching of the copper has to do with the use of chemical processes to etch the copper layers. This is important due to the presence of the copper beneath the remaining resist layer, as well as the unwanted exposed copper.
By using the chemical processes, these unwanted coppers are removed. However, to prevent exposing the wanted/needed coppers, a tin plating is used to guard the section of the panel meant to be covered.
9. Applying the Solder Mask
With the removal of the unwanted coppers, the connections and conducting areas of the board will now come into full view.
What’s left at this point is to apply the solder mask. The following processes must be implemented to achieve a successful solder mask application on the PCB:
- The cleaning of the panels.
- The application of the solder mask to the board sides of the PCB.
- The panels, after cleaning, need to be covered with an epoxy solder mask ink.
- After the above, the PCB need to be exposed to UV light. Doing this helps to keep the covered portions unhardened and to have them removed.
- It is now time to cure the solder mask. This can be actualized by passing the circuit board into an oven.
10. Surface Finishing
You can now begin the process of making the PCB electronics presentable. It has to do with the chemical-induced plating of the board with either silver or gold. This helps to bolster the solderability of the board.
Note that there are different variants to PCB soldering. So, you may want to consult your circuit designer for inspiration and direction.
11. Silkscreen Application
Applying the silkscreen is a vital step in the PCB electronics manufacturing stage. It has to do with the placement of ink-jet writing on the PCB’s surface. Doing this helps to enable the indication of the different markings, logos, symbols and vital identification details on the PCB’s surface.
Without the silkscreen application, it is quite impossible to identify which component is to be placed on the board and where it is to be placed.
12. Test Your PCB Electronics
Your board is almost ready for use, but you don’t want to use the excitement of that to forget how important it is to test it.
The testing procedure is an important element in the identification of design errors and other anomalies that might arise.
The following are some of the testing methods you can use:
- Electrical Testing: as the name suggests, it has to do with confirming if the circuit board meets up with the electrical requirements. An example of such electrical test is Flying Probe Testing. It has to do with the testing of the electrical performances of each of the nets on the PCB. The testing process also covers the validation of the circuit’s proper connection and the absence of short-circuiting on the board.
Additional Step: while most PCB electronics manufacturers stop at the electrical tests, we can also go the extra mile to be sure your board works as expected. One additional step we can take is to make a profiling and V-scoring of the circuit board. This has to do with the permission/enablement of the board to pop out from the panel. Note that it goes both ways – using the v-groove process that cuts diagonal channels along both sides of the board and the router process that retains smaller tabs along the PCB’s edges.
Wrapping Up: How to Get Started with PCB Electronics Manufacturing
The process of manufacturing your circuit board, including the fabrication and component assembly needs to be handled by a professional designer. At Hillman Curtis, we offer a full-suite service through our Electronics Contract Manufacturing (ECM).
Our job as contract manufacturers includes but are not limited to sourcing the components for the job, fabricating the board, assembling the components and testing the board to be certain of the performance.
You can trust on our service to not only manufacture the PCB as per your schematic designs, but to also work with your budget, any additional customizations you may need and to offer professional guidance every step of the way.
