You may have come across black PCB. Its true color is the solder mask, and not the PCB itself. Most of the time, PCBs are colored green. A few cases exist where other colors are used. In this case, we will be focusing in black PCBs.
One major reason why solder masks are black is due to the light reflection, which isn’t desired for such circuits. Let’s continue to know more about black pcbs.
What is Black PCB?
Black printed circuit boards are color boards having a black solder mask. Most of the time, this black coating happens to be the only material with black color on the board. However, in some other scenarios, the materials for black PCBs could be black as well.
What is Matte Black PCB?
Matte black PCBs are more common today due to their great performance. It looks more attractive to the plain and normal black PCB.
Using matte black for your pcb helps in giving your board a softer and duller finish in contrast to other colors. With this feature, it doesn’t reflect too much light, but it bounces anytime it gets exposed to any heavy light.
Furthermore, the matte finish prevents easily noticeable scratches from getting to your board. One great benefit of matte black PCB is that it helps you detect problems of board’s possessing this color variant.
Black PCB Board Design Benefits
Black PCBs are very versatile. This means that you can use different coatings having different properties to cover it. This solely depends on what you want.
Therefore, you should consider some properties like moisture, electrical, and moisture resistance. This is to ensure that the PCB is set for effective use. Furthermore, black PCBs are usually visually appealing, most especially when there are shiny components on the board’s circuitry.
Its reflection to light is low. Black is known as a poor light reflector. Therefore, it is utilized in areas where there’s no need for light reflection.
It is also difficult to plagiarize the black pcb board. This is because figuring out its copper features done come easy when looking using the human eye. This is what makes it difficult to pirate just by following the design traces of the board.
Another reason why it is difficult to plagiarize is its high production cost, when compared to some other boards.
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Best Design Tools and CAD Software for your Black PCB
Making use of the best tools for your design is very significant. This is because they play a great role in designing a black PCB’s blueprints. Below are the best available software tools that will be of great help to you.
Solid Works
This has a powerful design, therefore making your electronic design work easier. It is attributed to bidirectional mixing, with its PCB solutions offering a strong cooperation of CAD and PCB designs.
KiCad EDA
This is appropriate when creating designs that have no limits. With this tool, users can create a layout very quickly. This layout may feature about 32 layers of copper. KiCad EDA works fine for producing inspected designs and expert layout annotation.
DipTrace
Considering the amazing capabilities and intuitive interface of DipTrace, it becomes easy to use. This is why design engineers of PCBs find this software very useful and suitable.
DipTrace’s single environment ensures that you enjoy the true supremacy of converting circuits to boards directly. Lastly, with this tool, you will be able to get the manual routing and board design.
Altium Designer
This tool for your PCB design is the most popular right now. This is because you can stimulate your circuit just by using this software. Altium designer helps in bridging all the significant areas of the design procedure of black PCB.
Furthermore, it ensures that the user has a connection to the design. With this tool, you can be sure that your classified diagram and design reuse are easy to use with the designer software’s interface.
XCircuit
This tool is great for design automation and schematic presentation. Furthermore, producing netlists from the circuit as well as related figures through symbolic capture comes easy.
Structure Types of Double Layer Black PCBs
Trace: Traces are called simple metal buses made of copper, which connects the black parts of the PCB and the legs.
Pad: For black PCBs with double layers, the pad is referred to as a small copper, which are connected to the parts’ legs. With the help of the solder, you bond the pad and the legs
Solder mask: The solder mask is the layer that is added to the top area of the board’s copper layer. Usually, it comes black in color and helps in preventing pads from coming in contact with conductive black fr4 materials present on your black printed circuit board.
Top and bottom layer: Black PCB’s upper layer helps in mounting all the PCB segments. For the bottom area, you fasten the segments via the openings.
Black PCB Etching: Applicable Methods
Below are some of the major applications.
Plasma Etching
The generation of plasma is done under very strict conditions. It is useful in the cleaning materials that are left behind after drilling the holes on black PCBs.
Chemical Etching
Chemical etching is usually done with ammonium persulphate or ferric chloride. Both liquids are corrosive, while dissolves unwanted copper away to help define that circuit board you desire.
Laser Etching
Laser etching is the removal of one fine layer from the black PCB (photosensitive). This is achieved using a laser beam to help expose or reveal the copper underneath. Through acid birth, can the corrosion of the copper take place.
Black PCB Etching: What are the Processes Involved?
Below are the steps to take when etching a black circuit board.
Get the design of your black circuit board and print it out
First, use the software design you desire to design your circuit board. Next, get a glossy paper and print the layout on it.
Slice up the copper-clad and sand it
In this step, cut many required layers from the copper clad and make sure their sizes are the same. After doing this, sand them. Your sanding has to focus on the copper-clad edges. This ensures your etching comes out nice.
Then, transfer the circuit to the copper clad making use of a heatless toner or any heating element. After this step, you can start etching. By using the chemical process of etching, dip the copper clads into ferric chloride solution and allow it to stay for around 8 minutes. Furthermore, check these traces and get rid of any unwanted copper found in-between the traces.
Rinsing, Cleaning, and Inspection of the Black PCB
Once you are through with the etching process, use clean water (tap preferable) to rinse your black circuit board. Next, rub alcohol on the pcb board to clean it. This helps to wipe off excess ink that may have gotten to your black pcb board.
Lastly, check your black pcb board properly and make sure that all the details are well in place.
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Surface Mount Technology (SMT) Methods Applicable to Black PCBs
Type 1A
For this assembly, the soldering of the components of surface mounts are done on the black PCB’s component side. This assembly form is the simplest.
Type 1B
This is made up of components of surface mount found on any of the black PCB sides. For this reason, its functional density becomes very high.
Here, you can save a huge space. Furthermore, the secondary side’s components are first placed using an adhesive, and then reflowing is done.
Type 2
The black PCBs primary side is made up of both surface mount and through-hole components. For this assembly, the black PCB board’s secondary side has the surface mount components.
Black PCB Soft Soldering vs Hard Soldering: What’s the Difference?
Soft soldering may only be applicable for black fr4 material of black PCB requiring temperatures below 400 degrees centigrade.
Here, you apply some heat at the ends of the filler metal where they ought to be joined. Next, the workpieces are strongly connected by heat. One strong requirement for this method of soldering is the soft lead.
Furthermore, black PCB hard soldering can also be called silver soldering. The temperature necessary for this to hold must be higher than 480 degrees. In contrast to the soft soldering type, it makes stronger joints.
For this, two metal elements are united by the solder. This is achieved by spreading it to the components’ holes that have been unlocked as a result of high temperature.
Important Tests to Conduct for Black PCB
Burn-in Test
This helps in detecting early failures, as well as establishing the capacity of the load. As a result of its intensity, the burn-in test may be destructive to some of the parts you are testing. This test helps to push power via electronics. Therefore, this happens at the maximum capacity that lasts for 49 to 168 hours nonstop.
In addition, if your black PCB board somehow fails this test, it is called infant mortality and boards having an infant mortality that is high are not suitable.
In-Circuit Test
This test is the most robust of all the black PCB tests in existence. This test deals with using fixed probes, which are laid out to match your black PCB’s design. With these probes, you will be able to check your solder connection’s integrity.
X-Ray Inspection
The x-ray inspection is a test that serves as a tool for inspection. During this test, it is easy for the technician to locate errors early when the manufacturing process is on. Furthermore, it checks hidden elements and prevents its visibility like connections.
Flying Probe Test
This test works with the help of needles that are attached to your probe, which are gotten from the basic CAD. The flying probe test doesn’t power the board up.
Optical Inspection (Automated)
This is mostly utilized in detecting problems very early. If there’s an issue, production is stopped very early. Furthermore, this test integrates either 3D or 2D cameras, which can take photos or pictures on your black PCB.
Next, the software goes ahead to compare your board’s photos to the detailed design. Any board that fails to match the required design level is immediately marked for inspection.
Functional Testing
For this, the customer provides the specifications and functional tests. This consumes much time; however, it saves money and face.
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Design Parameter to Consider During the Design Rule Checking of Black PCBs.
Minimum Width
Here the DRC checks if the widths of the GND and VCC are in line with a black PCB’s design parameters. Also, this checks if the coupling between the ground wire and power supply is tight enough.
Minimum Area
Here, you will run this DRC to help in checking if the board’s overall size, as well as the size of the black PCB board’s components works with the allowable area. Therefore, this helps in notifying the board’s designer if this board doesn’t follow the designed outline of the black PCB.
Misaligned Via Wires
Here, you utilize the DRC in checking if the two layers having similar logical nets do not align through a connection or do align. If this inserted via doesn’t align with the metal crossing, then a flag for via misalignment is raised.
Silkscreen shots
For this, the DRC checks if the icons and labels that are added on black PCB can lead to any shorts. Then, if this is the case, it notifies the designer to make changes accordingly.
Minimum Spacing
With this parameter, you can check the least spacing that is present between the components on the board.
Digital and Analog GNDs
This checking rule ensures that the digital and analog circuit found on the black PCB boards features separate grounds.
Black PCB Applications
Below are the common applications of matte black PCB.
Medical devices
Matte black PCB isn’t just useful in devices used in medicine, but plays a great role in monitoring, testing, and diagnostics.
Automotive
Using multilayer matte black PCBs in the automotive industry helps engineers feature new features for electronics like enhanced GPS systems. Also, it ensures that existing systems are updated as a result of its ease in interchangeability.
Consumer Electronics
Matte black pcbs are useful in computer electronics like kitchen appliances, laptops, and mobiles.
Industrial Electronics
Matte black pcbs are necessary for appliances requiring high power. This is because they work great in severe industrial conditions.
Conclusion
We hope that you were able to gain so much from black pcbs. It features several advantages, which you should consider whenever you’re choosing a color for your solder mask. Choose black pcbs today and you’ve just made a great decision.
