What is Glass PCB?19 September 2023
In simpler terms, a flat layered PCB (Printed Circuit Board) resembles a sandwich consisting of non-conductive material with layers of copper circuits inside or on the outside. For complex tasks, they can have as many as a hundred layers of copper.
We encounter wires and PCBs every day, and they’re vital for modern electronics in things like high-tech gadgets, computers, and home appliances. PCBs vary in shapes and sizes, and engineers design them by creating a copper-covered circuit and then employing a special solution to eliminate any excess copper that is unnecessary.
What is Glass PCB?
Manufacturers often use glass PCBs in the production of LCBs (Liquid Crystal Displays) and LEDs (Light Emitting Diodes). They construct these PCBs primarily with glass. Engineers use a UV curable mask to transfer the circuit from the glass PCB to the copper plate. These UV curable masks have the benefit of accommodating smaller track widths and find application in large-scale PCB production as well.
The process involves the solidification of uncured etches when exposed to UV radiation.We apply an opaque film that contains the circuit’s image to the copper board and then expose it to UV light through this film. This process imprints the circuit design onto the resist film. Once we remove the uncured film, the circuit is ready for subsequent processing.
Once we remove the uncured coating, the circuit is prepared for etching. It’s worth noting that we use a straightforward solution as the developer for this purpose, much like using baking soda to remove uncured UV protection.
There are two types of UV-resist films: positive and negative. For positive films, the photoresist remains intact when we apply the developer, while it dissolves the unexposed portions. This is the opposite for negative films, where the unexposed areas remain, and the exposed areas dissolve. The choice between positive and negative films depends on the specific requirements of the process.
Types of Glass PCB
Many different materials can be used to create PCBs (Printed Circuit Boards). These materials have unique properties that make them suitable for specific conditions. Let’s take a look at some types of Glass PCBs:
- Tempered Glass:
- Tempered glass is a special type of glass that has been processed to be very strong and durable.
- It is difficult to break and can withstand high levels of pressure, around 4-5 times stronger than regular glass.
- Tempered glass remains undamaged even when a 1kg steel ball is dropped from a height of 1m.
- Military devices, such as night vision cameras, infrared and far-infrared views, and satellite technology instruments, utilize it, including optical prisms and windows.
- Tempered glass also finds applications in research instruments such as UV and IR windows and high-precision devices.
- Sapphire Glass:
- Glass containing sapphire crystals has excellent thermal properties and is chemically inert.
- It offers exceptional electronic and structural characteristics.
- Sapphire glass earns its reputation for its valuable qualities, including infrared conductivity, exceptional heat resistance, and chemical durability.
- Quartz Glass:
- Microelectronics, electric light sources, advanced manufacturing, and far-infrared radiative heaters commonly employ crystalline quartz material.
- It has a relatively low thermal coefficient and can be challenging to shape.
- Quartz glass is highly stable and transparent to both UV and infrared light, making it suitable for various applications.
Advantages of Glass PCB
Glass PCBs may not offer specific electrical advantages, but they possess numerous other benefits. Transparent glass circuit boards find use in applications like LED lighting, 5G technology, and LCD displays due to their 360-degree light-emitting properties and effective wire concealment capability. Presently, glass PCBs find extensive use in critical applications, including advanced LED lighting and other sophisticated lighting solutions.
- Stable Connection
- 360-degree illumination beam
- Chemical resistance
- Ability to work again after being faulty
- No Shocks
- Heat-resistant and tear-resistant
- It does not require a heat sink.
- No light attenuation
- Low deformation rate
- Flat and transparent
How to make Glass PCB?
Creating Glass PCBs differs from traditional methods. Designers expose the circuit design on a glass plate using light and then etch it, ideal for mass production.
- Glass Plate
- Copper Foil (1 oz) or Copper Clad Board
- Lithium Hydride Battery or Coin Cell Battery
- LED Light
- Prepare the Circuit Design: Convert the circuit diagram into a suitable image file (e.g., GIF or JPG).
- Print the Design: Use a laser printer to print the design on a special film, creating a negative image of traces and pads on the glass.
- Adhere Copper Foil: Apply specialized glue to the copper foil and place it on the glass, securing any loose parts.
- Apply Photoresist: Cover exposed copper foil areas with photoresist material. Cure it with UV light or heat.
- Light Exposure: Use UV light for PCB exposure. It typically takes around 10 minutes per side.
- UV-Vis Absorbers: Alternatively, use UV-Vis absorbers with a bright white LED for faster production (a few seconds per side).
- Develop Resist: Prepare a developer solution (with baking soda or rinse powder) and immerse the copper board for 1-2 minutes. Unexposed portions will dissolve, leaving solid resist tracks.
- Clean and Etch: Clean the glass with detergent and warm water. Etch the glass back with hydrofluoric acid, creating space for components.
These steps enable efficient Glass PCB fabrication, suitable for applications like LED lighting, 5G technology, and LCD displays due to its unique properties, such as 360-degree light emission and effective wire concealment.
Hey there, I’m Anshul Pal, a tech blogger and Computer Science graduate. I’m passionate about exploring tech-related topics and sharing the knowledge I’ve acquired. With two years of industry expertise in blogging and content writing, I’m also the co-founder of HVM Smart Solution. Thanks for reading my blog – Happy Learning!