Here's my thoughts: (a) use fresh chemicals. (b) If you are using 30% NH4OH, cut back on the DI H2O. (c) once mixed, this etchant has a short shelf life (several hours at best) I use 25 ml of NH4OH (50%), 25 ml DI H2O and about 0.5 ml H2O2 (3%). Are you etching PCB copper or solid Cu slugs? -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of [log in to unmask] Sent: Thursday, July 13, 2017 2:44 PM To: [log in to unmask] Subject: Re: [TN] 1:1:1 Copper Etchant, Delineation Region of copper plating interface Dell - Internal Use - Confidential That's the whole problem...... I only have the listed chemicals to work with........ Victor, -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Tony Lentz Sent: Thursday, July 13, 2017 2:37 PM To: [log in to unmask] Subject: Re: [TN] 1:1:1 Copper Etchant, Delineation Region of copper plating interface Hello Victor, Increasing the concentration of the hydrogen peroxide will make this solution more aggressive as a copper etchant. The ammonium hydroxide is mainly there to aid in keeping the copper dissolved as a copper ammonium ion. Best regards, Tony Lentz Chemist / Field Application -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of [log in to unmask] Sent: Thursday, July 13, 2017 1:17 PM To: [log in to unmask] Subject: [TN] 1:1:1 Copper Etchant, Delineation Region of copper plating interface Fellow TechNetters: Is there any possible way to make the above stated etchant STRONGER/AGGRESSIVE: Here are the chemicals: Perhaps by varying the volume of one of the three constituents. 1 - Ammonium Hydroxide, 28.0 - 30.0% 1 - Hydrogen Peroxide, 3% 1 - Deionized water Victor,