Contact US

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Streaking during spin coating

Streaking during spin coating

Streaking during spin coating

I am spin coating a polymer solution in toluene (bp=110C). However, after spin coating, I see streaks of the polymer on the substrate. Any idea as to how to solve the issue? I have played with polymer concentration and speed without any effect.

RE: Streaking during spin coating

I've been there on this one.  Describe the streaks.  It could be particles in the polymer, which cause a defect known as comet tailing.  It could also be a function of how you are wetting the surface, fluid viscosity, ramp rate, or even your surface preparation before coating.  

Aaron A. Spearin
Engineering Six-S'$

"The only constant in life is change." -Bruce Lee

RE: Streaking during spin coating

The streaks emanate from the center of the substrate to the periphery. I dont think it is due to particles in the solution, as I filter the solution with a 0.7 micron filter. I apply the solution by covering the entire substrate with a thin layer of solution and then spin-coating. Reducing the concentration and increasing the spin-rate reduces the streak formation to some extent, but not entirely. Also, the viscosity is that of water.

RE: Streaking during spin coating

So it sounds like a "starburst" type defect where these streaks are sort of a "ripple" of coating, but not a bare area of coating.  It could be that air in the coating chamber is not solvent rich enough, should be saturated vapor. This should delay the evaporation of the solvent from your surface, preventing localized zones of cured, dried, concentrated or viscous fluid.  I've also had luck dispensing the fluid while the coater is running, in general my conditions were a dynamic dispense at about 300 rpm to spread the solution, then ramp up to 1000 for spin-off, then 3000 final spin-off/drying stage.  

Aaron A. Spearin
Engineering Six-S'$

"The only constant in life is change." -Bruce Lee

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Design for Additive Manufacturing (DfAM)
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a part’s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close