etching

[bigchasbroon]

Hi I need to pick your brains again... I have etched about 6 boards now and Im getting better with press n peel, the first two were scrapped but now my boards are near perfect each time, but I have a couple of questions regarding etching.

first of all if i leave a board in etchant for say overnight, will it eventually damage the tracks. Currently I sit and watch for about 1 1/2 to 2 hours until its ready but if i could just leave it that would be better.

Secondly I have made about 6 boards now in the same etchant, the etchant has turned blue from the copper and I was wondering how long i can keep using it for? will it just become less and less effective?

[ItZaLLgOOd]

What kind of echant are you using?  How big are the boards? 1 1/2 - 2 hours seems excessive.  With the peroxide and muriatic acid the longest I've waited was 10 minutes.

[bobp1339]

I am by no means an expert, having only done 9 etchings... but I get good results by doing the following:


I have an all glass bread baking dish that I fill halfway with water. I put this in the microwave for 2 minutes.
I put the etchant (I use Ferric Chloride from Radio Shack) into a gallon sealable freezer bag (ziplok,etc) I put in just enough to cover the board when the bag is laying flat. (I don't measure, I just pour some in.)
I place the board in the bag and seal it.
By that time, the microwave is done. I remove the dish from the microwave and place the bag into the hot water.
Then I gently agitate the bag for about 5 minutes.  By that time, 90% of the copper is removed and I continue to agitate and check it every 30 seconds or so.
I usually have a fully etched board in 10 minutes.

Once I have removed the board and rinsed it, I seal the bag and set it in a plastic container with baking soda in it. I put the baking soda in the container to absorb and neutralize any etchant that may leak from the bag.

I have used the same bag on 3 boards now, adding just a bit more etchant each time to "freshen up" the solution. I am not sure how many more etchings I will get, but once it starts taking longer, I will replace the etchant.

Bob

[bigchasbroon]

I cant remember what type of etchant. It was beads that I mixed with water but the packet has long since gone. I am probably exaggerating but it does take up to an hour. I really just wondered if there was any harm done in leaving it too long.

[Jarno]

The copper tracks will get thinner as the copper gets etched away from the sides (from under the etch resist). I did some etching in the shed this spring and that took about half an hour (even though I heated it with boiling water "au bain marie").
A couple of days ago I did a few using a fresh (and hot) solution of Ammonium Persulfate and those boards where done in like ten minutes.

[makaze808]

WAYYYYYYYYYYYYYYYYYYYYY TO LONG THERE DUDE,get some new etchant and mix a little stronger. as long as your heating it prior to use it should be no longer than 10 minutes, I use ferric chloride and it never takes more than this.

Woz.