There’s a rapid expansion of the PCB market, just to meet the needs and requirements of the different electronic and electrical devices. This is why you will see ceramic PCBs, metal OCBs, and even transparent PCBs.
Whether you believe it or not, there have been revolutionary changes brought into the PCB industry since the transparent glass technology came to be. Transparent PCBs are utilized in different LCD and LED devices. However, the most promising of all its uses is its utilization in the 5G network. This will surely change the communication concept forever.
The transparent PCB can have a luminescence of 360 degrees, 140lmw and above value for the rendering index. There’s no need to include the heat sink and light attenuation does not occur.
If you wish to learn about the most advanced printed circuit boards and stay updated with the remainder of the whole world, then take your time to go through our guideline on transparent PCBs.
Transparent PCB Substrate
There are two main substrates for transparent PCBs. It’s either ceramic or glass. Ceramic transparent PCB substrates have high thermal conductivity compared to glass. However, it has a slightly lower transmissivity. Its transmissivity is about 75 to 85% compared to 99.5 to 99.99% for glass.
Transparent Glass PCB
Before considering the uses of transparent PCBs, as well as the description, let’s quickly consider what glass is, as well as its use in the printed circuit board industry.
Most times, glass is made of soda, limestone, ash, and sand. These four materials are usually recycled, which makes them eco-friendly. Now, let us consider the most frequently used glass materials.
A glass material you will see very frequently is tempered glass. Tempered glass is referred to as a pre-stressed and reprocessed glass. This ensures more durability. In addition, its strength for shock absorbing and impact are usually higher, which are useful for extreme cases.
The hardest and strongest by far globally is sapphire glass. Due to its high dielectric and thermal properties, sapphire glass is useful in many high-end and complicated devices. Its applications are relevant, even in satellite and space devices and technologies.
Now, we know much about glass, as well as its materials, now let’s focus on transparent PCBs. These are printed circuit boards manufactured from transparent glass. They also have an illumination facility ofn 360 degrees. This means light will be able to pass through, ensuring you see some illumination from all the sides.
Using glass as your substrate comes with some unique benefits. These benefits come from its tear-resistance, heat resistance, deformation, transparence, flatness, etc. Under high temperatures and after working for long hours, the rate of deformation is extremely low.
This is one good reason why so many devices also utilize it to be attractive. However, one great advantage, and probably the best is their wire decoration, which is invisible. This truly helps in elevating the devices’ value.
Benefits of Transparent Glass PCBs
Already, glass material is advanced. Whenever it is utilized in making transparent printed circuit boards, it will surely add some value to constructions of circuit boards. Transparent PCBs are not exempted
Light can pass through transparent PCBs. This makes the transparent PCB versatile and better. Also, transparent glass pcbs are usually flat. This means it will have great symmetrical functionality and less flaws. This increases the efficiency and durability of these devices.
These transparent pcbs also have high heat resistance and temperature. Glass has the ability to withstand a temperature of about 1000 degrees. In addition, you can produce it easily in large quantities for PCBs and semiconductors.
Glass transparent PCBs can be manufactured easily. This is because glass can be gotten from recycled items like sand and ash. This makes glass transparent pcbs lower priced compared to ceramic pcbs. Therefore, with glass transparent pcbs, the cost of production of all your devices will be lowered.
Thanks to heat, dust, and water resistance, the deformation rating of glass is least. This ensures that glass transparent pcbs can withstand use for a long time even in very extreme conditions.
Heat sinking isn’t necessary here to manufacture this type of transparent PCB. Therefore, it boosts the rate of production further.
Ceramic Transparent Circuit Boards
This type of transparent circuit board can either be magnesium oxide, aluminum oxide, Al-Mg , and yttrium oxide spinel. These ceramic transparent circuit boards usually come with transparent substrates, as well as solder masks (glass-based). However, there is no transparency in the conductive part.
Ceramic Transparent Circuit Boards: Advantages
- Great thermal conductivity of 26+W/mK
- Small and stable CTE (Coefficient of thermal expansion)
- No absorption of water and great electrical insulation
- So many optical features available
- A high temperature resistance of over 2000 degrees Celsius
Transparent Ceramic Circuit Boards: Applications
The transparent ceramic circuit boards are applicable in the following areas.
- LEDs working with high power
- Infrared windows utilized in missiles, aircraft, etc.
- Optical sensors
- Sodium lamps with high pressure
Transparent Flexible PCBs
This type of transparent PCB can be referred to as flexible printed circuits that make use of PET thin film. These PET materials can either be white, transparent, light green, light blue, or white. Clear flexible printed circuits are usually different from the normally seen types. This is due to the PET materials that are transparent.
There are flexible PCBs, where just the substrate is transparent. Also, the pads and conductive traces are not transparent, but visible. There are transparent flexible printed circuit boards, which includes the conductive traces. They are completely clear. Here, an innovative method of manufacturing is utilized. In this case, the circuit is always clamped in-between two materials (transparent), to help protect it, thereby making it invisible when checked from outside.
Advantages of Transparent PCBs (Flexible)
Below are some benefits of the flexible type of transparent PCBs
- They come with lots of great optical features
- They are flexible, twistable, foldable, arbitrarily movable, and bendable in spaces of three dimensions.
- Achieve thinning, miniaturization, and lightness of products
- Flexible printed circuits save around 90% of the weight of the product compared with the rigid printed circuit boards having similar volumes.
- This transparent PCB’s manufacturing accurateness reaches the nano or micro level.
Transparent Flexible PCB Applications
The transparent flexible circuit boards are applicable in the following areas.
Flexible transparent circuit boards are widely utilized in ABS systems, mobile phones, cameras, instrument panels, automatic control, medical devices, and places where connections are needed in spaces that are closely packed.
Flexible pcbs that are fully transparent can be utilized in electronic devices, contact lenses, as well as electronic skins.
Transparent PCB Board Design
Transparent PCB Board: Circuit Design Preparation
Designing the transparent pcb board can be done on many different platforms. You can make use of the software “EASYeda.” This software is free to use, can be learned easily, and you will easily find the components.
Next, create a schematic diagram for that circuit. Next, model the layout of your PCB, after which you will make use of the autoroute tool in routing your circuit’s paths. For beginners, this stage may look a bit complex. However, you should be fine working with a few tutorials.
You will find some unwanted component diagrams and texts. For transparent pcb boards, we only need the pads and tracks. Therefore, after getting satisfied with the design, isolate the pads and oaths layer in your layer pallet, after which you can export the image as a PNG file.
The negative photoresist is used. This means that there is a need for the resist to get exposed to light. This is why you must utilize the option “white on black” for the dialog you are exporting.
Transparent PCB Board Design Printing
By now, the exported image, which you have designed, is with you. The OHP print’s purpose is making a mask that blocks the resist UV light exposure in regions that are not wanted. To achieve this, the OHP print’s black areas have to block light properly.
If this is not so, the light will leak though. Adding just a layer of print will not block the light effectively. Therefore, align three prints and then place them on each other. Also, glue them to keep them steady.
Gluing Your Copper Foil to Glass
Now, we will be gluing your copper foil on glass. During these final stages, the unwanted copper will have to be removed. This is achieved by dissolving it using ferric chloride. To make the whole process time expensive, choose a copper foil that is thick. One as thick as 0.05 mm is okay.