[OS] SPIN COATER

Low-cost Open Source spin coater.

This project is a spin off of Jan’s Tiepelt ideas Fabubox and Fabublox. I have collaborate with him for the manufacturing of the solar cell and the strain gauge shown in this article.

Check the project in great detail →HERE←

What is a Spin Coater and why its important for modern manufacturing.

Spin coating plays a pivotal role in various sectors, including the semiconductor industry, MEMS (Micro-Electro-Mechanical Systems), sensors, integrated photonics, and antennas. It serves as an integral step in the manufacturing process, facilitating the consistent fabrication of thin films while maintaining precise control over thickness at the nano to micro order of magnitude.

Commercial spin coaters available off the shelf typically come with a price tag of around $2,000. However, we have identified an opportunity to significantly reduce the associated costs by designing specific components and opting for a smaller vacuum pump. Through this approach, we have successfully developed a closed-loop spin coater utilizing readily available elements found in Fab Labs, resulting in a cost reduction to approximately $80.

I find great satisfaction in the innovation applied to the mechanism designed for sustaining vacuum transmission while allowing rotational freedom. This mechanism is particularly noteworthy for its ability to maintain stability even at rotational speeds of up to 11,000 rpm, ensuring effective vacuum transmission. Initially, my exploration on the internet yielded expensive alternatives, prompting me to embark on the creation of a custom solution. To date, the system has demonstrated remarkable reliability, consistently delivering vacuum without failure.

While, like any vacuum device or process, there are inherent leaks, my system boasts significantly smaller leakages compared to the suction capacity. Operating our pump at 9V with a specified 12V rating, we have successfully achieved a rotational speed of 3,000 rpm, demonstrating optimal performance even with reduced vacuum levels.

The device’s construction involves a rotor and stator assembly, securely fastened together through the utilization of the inner portion of a bearing. Cleverly engineered, the bearing incorporates O-rings along its edges, intricately complicating the airflow path in areas other than the designated tube leading into the component, effectively minimizing unintended air leaks.

In the literature, it is commonly established that the thickness of the spun layer is proportional to the inverse of the square root of the angular velocity.

We used ellipsometry to measure thicknesses from our spin coater vs. a robust spin coater from MIT Nano, and the comparative looks like the following:

With this technology, we built a hot plate and we were ready to make some single layer (or multilayer without registration) devices! We achieved to make a very good organic solar cell and a functional strain gauge: