The authoritative public forum
  for Metal Finishing since 1989
  

  -----

Removal of TOC glass coating using electroplating methods.

All, I am attempting to refine a method for removal of "stannic oxide" based transparent conductive oxide film bonded to the surface of borosilicate glass. my basic setup consists of a copper cathode and an alligator clip attached to a piece of TCO coated borosilicate glass that is slightly immersed into a 0.1 M HCl solution acting as the anode. Note that only part of the TCO coated glass is submerged into the acid bath while the portion of the glass containing alligator clip connection remains in air. DC 10V/0.1Amp is applied and localized Stannic removal occurs where the alligator clip meets the glass. I am looking for any advice on how to achieve complete removal. I have almost NO plating experience. Any input is welcome. -Adam

Adam Tomaino
Industrial Process Refinement - Pittsburgh, Pennsylvania, USA
August 23, 2011

---

August 23, 2011

Hi, Adam.

I have to admit that this removal method isn't making much sense to me. If you managed to remove the coating near the solution level, how would you get conductivity to the balance of the stannic oxide further down into the solution? It would seem that the process would stop as soon as there was a break in the conductive path.

What removal method do you even foresee? You have stannic oxide SnO2 on the glass, and you say that it is "removed" in the area of the alligator clip. What does "removed" mean . . . it pops off as dust, the tin is converted to a higher oxidation state, or what? Thanks!

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

---

You need chemical striping method, not electrochemical. Try simple immersion in mixture of 2 volumes nitric acid, 1 vol muriatic acid. Modify ratio until you get satisfactory results in terms of complete removal over reasonable time and less fuming. Very good ventilation or preferably an extractor hood of suitable material is advised.
G. Marrufo-Mexico

Guillermo Marrufo
Monterrey, NL, Mexico
First of two simultaneous responses -- August 26, 2011

---

I think that you may have better luck in removing stannic oxide with immersion in a warm, mildly alkaline solution that contains polyphosphates and a surfactant. The polyphosphates should help to solubilize the tin and also protect the glass from being etched.

Lyle Kirman
consultant - Cleveland Heights, Ohio
Second of two simultaneous responses -- August 29, 2011