Archive of the former Yahoo!Groups mailing list: Homebrew PCBs

I only use the thinnest cheapest Chinese ... 70x100mm PCBs  from EBAY

What do you mean by center punched?
Smacked a hammer and nail against the copper pads?
I would not mechanically abuse the copper like that.
Etch the hole ... with a PLUS sign to keep the drill bit from walking away from the target hole.

And etch time? 20 minutes?
I've been getting 4 to 6 minutes etching with room temperature.. same mix you do... 50mL muriactic acid to 100mL peroxide.

and
the only time it took longer is when the peroxide was low in the bottom of the peroxide container
soooooo....
I'm not a chemist so I can't declare why "old" peroxide takes 30 minutes while new peroxide takes less than 5 minutes.
 

 

I recently etched some thin brds .032 size with muratic acid and hydrogen

peroxide per 3/4 cup muratic acid & 1 & 1/2 cup hydrogen peroxide mixture. I coated the traces with liquid tin then center punched the pads. I started drilling the pads with a dremel like variable speed moto tool and brand new high speed drill bits only to have pads pull away from copper clad brd.  Why did this happen? Does anyone know as all I can tell is these are cheep orient type board stock bought in large pieces from a E-Bay buyer. It also took 15 to 20 min to etch boards at 120 degree temps. Professional positive brds in 1/16 thickness etched quite fast plus the pads did not pull away from fiberglass

at all. Am I right to assume that I got a bad batch of boards from E-Bay. Any input would help me figure this one out as other board stock did not behave like tis over the past 4 years also.