Where the
world gathers for metal finishing
Q&As since 1989


-----

Potassium hydroxide pre-clean solution temp inquiry

Good Day! I worked as a process engr. at plating somewhere in the phils., currently we are
on a cost reduction program and one of the projects that was assigned to me was consumption reduction of preclean/pre-treatment chemical solutions.
'Would just like to know if you have any idea on potassium hydroxide based pre-treatments? At what operating temperature they are best operable? Right now we are using them at 40C. At what concentrations also they are at best? By the way we are using copper based leadframes. Thank you and hoping for reply sooner.

Allan Vargas
Solderplating Process - Laguna, Philippines
2006

---

I currently use a pot. hydroxide solution. Our tanks stay around 120-130F. I usually use about 15 gallons of solution in a 500 gallon tank. I mainly plate brass and diecast so your application may vary. That is what works for us though.

Brad Standifer
Rack line / Barrel line operator - Knoxville, TN
2006

---

Everything in cleaning is a trade off. It normally cleans better or quicker when it is more concentrated, but it costs more and rinsing can become a problem. Hotter normally will work better, but you increase heating costs, water cost and exhaust cost.
I have no experience with PWB's but I would find it a bit unusual if it did nor contain a gluconate or EDTA and or a wetting agent (surface tension reducer).
Everything is a trade off and proprietary chemical vendors (quality ones) have been down that road and can tell you what optimum is or at least what the trade off costs are.(at least for their products).

James Watts
- Navarre, Florida
2006

---

Unless prices are greatly different in your part of the world, the simple way to reduce cost is to replace the potassium hydroxide with sodium hydroxide. The operating conditions are the same, say 65-85C
But it would be misleading to suggest that successful cleaners are just caustic. Most will contain silicates, chelates, detergents, etc. depending on the base metal and the type of soil you are trying to remove and the following processes.
You would probably save money by buying a proprietary cleaner and taking advice from the supplier rather than trying to teach yourself the finer points of cleaning technology.

Geoff Smith
Hampshire, England
2006