A transparent PCB is revolutionary! This advanced technology changes how we view and use PCBs by offering enticing benefits. In truth, many LCD and LED technologies use these PCB innovations due to their optical characteristics.
Interestingly, recent developments have made transparent PCBs the backbones of the 5G network. However, the big question here is: What is a transparent PCB?
In this article, we’ll discuss the details surrounding the concept of transparent PCBs and the different types.
What are Transparent PCBs?
A transparent PCB
Transparent PCBs are variants of flexible PCBs offering more benefits than their flex and flex-rigid predecessors. Undoubtedly, the innovation utilizes polyamide, making it incredibly flexible and thin.
Further, you can find these circuit boards in the automotive industry, particularly underbody controls, ABS systems, instrument panels, and other components. In addition, the computer peripherals industry also utilizes transparent PCBs to connect printers to hard disk drives.
Moreover, consumer electronics can also use transparent PCBs. Usually, you’ll find them in devices like training monitors, cameras, calculators, and mobile phones.
What are Transparent PCB Substrates?
Transparent keyboard PCB
Currently, you can use two substrates for transparent PCBs, including ceramics and glass. PCB variants with ceramic materials provide excellent thermal conductivity that’s better compared to glass models.
However, transparent PCBs with glass substrates provide enhanced optical transmissivity. Interestingly, ceramic substrates offer 75% to 80% transmissivity, while glass variants possess up to 99.5% to 99.99%.
Types of Transparent PCBs
A hand folding a transparent PCB
As mentioned earlier, we have two substrates used for making these PCBs, which translates to two types: Glass and Ceramic transparent circuit boards. So, let’s take a deeper look at these models.
Note: We also have transparent flexible PCBs, which we’ll discuss in this section.
Glass Transparent PCBs
Transparent PCB on a table
Usually, manufacturers produce the glass substrate from a blend of limestone, sand, soda, and ash. Thankfully, these materials are recyclable and eco-friendly.
Further, tempered glass is the most widespread variant of this substrate. Typically, manufacturers pre-stress and reprocess the glass to achieve high durability. Additionally, tempered glass transparent PCBs can absorb impact force and shock.
Also, sapphire glass substrates provide the most rigid and durable models of all glass PCBs. Therefore, you can find them in high-end electronic equipment due to their enhanced thermal properties and dielectrics. In short, PCBs made from sapphire glass substrates work in devices built for space and satellites.
And transparent PCBs made from glass substrates can transmit light omnidirectionally. Hence, you can reflect light via the circuit board from almost all angles.
Benefits of Glass Transparent PCBs
You can get the following benefits from transparent glass PCBs:
- Incredible resistance to wear and tear.
- Glass transparent PCBs offer maximum transparency.
- They’re resistant to heat and deformation.
- These PCBs provide an incredibly flat surface.
But it’s crucial to note that glass transparent PCBs placed under extreme heat for extended periods will deform at trickling speed. As a result, these variants are one of the most desirable variants.
In truth, glass substrates can withstand up to 1000°C, and their materials are simple to source, making them easy to produce. Lastly, glass transparent PCBs are significantly less expensive than their ceramic counterparts.
Drawbacks
While the glass PCB substrate offers maximum transparency, the copper traces will remain visible. However, manufacturers are working towards innovations to fix such issues for true transparency.
Ceramic Transparent PCBs
Transparent PCB
Typically, transparent ceramic PCBs feature mixtures of materials like Aron, magnesium oxide, Al-Mg spinel, Yttrium oxide, and alumina. For example, these circuit boards can have fine alumina powder at small levels, like 5 – 10%. In addition, this process shoots the hardness values from 6H to 8H.
Also, some manufacturers may use oil-based alumina liquid, while others utilize water-based alumina liquid to produce transparent PCBs. However, most of these boards use glass-based solder masks to achieve better transparency.
Advantages of Ceramic Transparent PCBs
Here are some pros of using transparent ceramic variants.
- Ceramic transparent PCBs provide various optical features.
- These circuit boards offer enhanced electrical insulation.
- Ceramic boards feature over 24 – 31.4 W/mk thermal conductivity.
- The boards absorb water at slow rates.
- These boards can resist high temperatures.
- Lastly, they have a low and stable coefficient of thermal expansion.
Applications
You can use ceramic transparent PCBs in optical sensors, infrared missile windows, high-pressure sodium vapor lamps, aircraft, and high-power LEDs.
Transparent Flexible PCBs
Flexible transparent PCB
PCB manufacturers can combine transparency and flexibility into one board by utilizing thin PET films. In addition, they can manufacture these circuit boards in various colors like light green, blue, white, etc.
Interestingly, these transparent PET materials can produce flexible PCBs with different benefits from regular variants. Also, some innovative methods can make the board’s conductive traces equally transparent.
To achieve this, the fabricator can clamp the board with visible conductive traces between two PET films, protecting and making the PCB invisible.
Pros of Using Transparent Flexible PCBs
- Transparent flexible PCBs offer numerous optical features.
- They can cut down weight and form factors. Also, transparent flexible PCBs can initiate product miniaturization.
- Unlike standard rigid PCBs, these boards can reduce overall weight by over 90%.
- You can twist, fold, move, and bend these PCBs as much as you like without damage.
- These PCBs offer stable dimensions.
Applications
Here’s a list of things you can do with flexible transparent PCBs:
- Instrument panels
- Smart contact lenses
- Automatic control systems
- Mobile phones
- Electronic skins
- Medical devices
- Cameras
- Electronic calculators
- ABS systems
Final Words
Transparent PCB on a table
The PCB industry is getting countless innovations, and transparent boards are among the top. Manufacturers are now employing these revolutionary changes to satisfy the requirements of various electronic devices.
In addition, transparent PCBs also support the movement toward miniature circuit boards and devices. More importantly, you can have limitless devices with transparent PCBs.
And you can find the three types of transparent PCBs mentioned, each offering unique benefits. For example, ceramic variants offer more durability, while glass ones provide more transparency. In short, flexible PCBs offer the best circuit invisibility.
Do you have any questions? Don’t hesitate to reach out; we’ll be glad to support you.
