02/15/2026
Home Brewed Cupric Chloride
For PCB etching. Muriatic (hydrochloric) acid, 3 % hydrogen peroxide, and copper. Supposed to be better than the ferric chloride I've used for decades.
I'm trying the "laser paint Ablation" method. Cupric chloride is supposed to have less undercut which allows for smaller trace width. I'll soon see if that's true.
It's cool that cupric chloride can be reused nearly indefinitely...supposedly. When it gets loaded with copper, just aerate with an aquarium bubble stone. I use a bubble stone at the bottom of the etch tank to gently agitate the PCB during etching anyway. I always etch vertical especially for two sided PCB'S.
The acid needs to be kept close to 40 deg C so I'm submerging my etch tank in a larger tank with water and a Caswell plating heater. Worked good to make the cupric chloride.
Now to finish getting the laser engraver dialed in and then work out the flipping it over part so both sides align. I'm using FlatCAM and it's 2-sided feature for creating the gcode for my cnc router for the alignment pins, drilling, and board cutout. KiCAD for schematic and PCB layout. Inkscape for processing KiCAD exports for import into Lightburn for the laser work. Yeah, a LOT of potential failure points. Hopefully comes out with smaller traces and better detail than the cnc relief milling method. If I get the process down, then I won't have to deal with the pain of relief milling height maps that don't help enough sometimes.
Anyone else using this method? Have any tips, tricks, or gotchas's to share?
