Etching a board set for my HRM build...

[ic-racer]

The relay board in the middle is flipped over to show the copper traces. The other boards are shown with the copper down to demonstrate that translucent look seen in many Dumble innards photographs.

[ic-racer]

The pictures used to come up with the HRM board traces. I found a datasheet for the original type trimmers and based the traces on that. So now I have to get these exact trimmers.

[ic-racer]

Tomorrow I'm going to go hunting around for a piece of wood-grained Formica.

[dano-rator]

Is it well documented that this is indeed wood grain formica and not just any old lam. turned wrong side up (which somewhat resembles tight grained mahogany)? Usually there is at least a satin sheen to formica which (granted picture may not be the right perspective) does not appear to be the case. And I haven't perused all the pics available. Just wondering out loud. The devil, after all, is in the details.

Ps. boards look great.
Have fun
Dan

[ic-racer]

I checked out some samples today. The Formica brand was the closest to 1/16 of an inch, but slightly thinner. Indeed the back side has a wood-like texture, but most of the pictures I have seen show a wood pattern.

The brand Wilsonart was thinner and probably not suitable.

The clincher was that the local lumber shop wanted a 36" x 8 feet minimum order. I didn't even ask how much it would cost. I'll have to check some other sources.

[Structo]

Yeah if you can talk to a installer he would probably have scraps, but how many people even use that stuff anymore in their kitchens?

What are you using for etchant solution. Radio Shack doesn't carry it anymore.
I tried all six of the stores in my town and nobody had any left.
They quoted environmental reasons for them not carrying it any longer.

There is a formula on the net how to make it with common chemicals.

[ic-racer]

Yeah if you can talk to a installer he would probably have scraps, but how many people even use that stuff anymore in their kitchens?

The experience got me thinking that the reason MrD may have used the woodgrain is that he got some scraps for free or little money and they just happened to be woodgrain, so he used it.

What are you using for etchant solution. Radio Shack doesn't carry it anymore.
I tried all six of the stores in my town and nobody had any left.
They quoted environmental reasons for them not carrying it any longer.

There is a formula on the net how to make it with common chemicals.

I got mine here. They are local to me, but since its a powder, I suspect they can ship it anywhere.

Dry Concentrated Etchant $3.50

http://www.ceitron.com/tech/datak.html

BTW that Circuit-Fix Kit they sell seems like a cool thing for modding circuit board amps. I have a JCM900 Marshall on the back burner.

[Structo]

Odd that most of their pages haven't been updated since 2004?

I never thought about the powdered etchant. Thanks


You know years ago when I used to make quite a few of my own boards, the one thing I found the really helped and could make or break a good trace was to get the copper very very clean.
We used to wash them with borax and scrub them very good.
Then didn't touch the copper with bare fingers because of the oils on the skin can cause adhesion problems.
That was using the stick on traces and photo etching.

[ic-racer]

Slowly populating the boards.

[martin manning]

The boards look really good!

I've decided to give the Pulsar system a try. I should have it within a week, and I'll report back with findings. The special materials aren't very expensive, especially if the results are reliable.

BTW there is a note on the Pulsar site that says the laminator doesn't work with the P'n'P Blue stuff (not enough time/temp), which was something I had wondered about.

I'm also very interested in trying the 1 part muriatic acid/2 parts hydrogen peroxide etchant as described on the Gootee site linked above. Very easy to get and as fast as ferric chloride by that account. Anybody else tried it yet?

MPM

[Structo]

I'm also very interested in trying the 1 part muriatic acid/2 parts hydrogen peroxide etchant as described on the Gootee site linked above. Very easy to get and as fast as ferric chloride by that account. Anybody else tried it yet?

MPM

OK, I knew I had read about a home brew etchant.

I used that same formula when I was relicing some guitar parts.

I tried both straight acid then the hydrogen peroxide mix, the peroxide really makes the acid etch faster. Like almost doubles the strength of it.

If you try it, remember your chemistry 101.
Always add the acid to the peroxide for safety reasons.

[Aurora]

We have used the hydrogen peroxide mix at work for years now, when our etching machines went down for one reason or another. Works OK, except for the nasty fumes - ensure good ventilation!

The danger though, is in making the mix too strong, which results in serious underetching ( etching in sideways in the tracks).
The original recipee published the the old "Reference book for Radio Engineers" gives the mix of 1:1:2 of 40% hydrochloric acid, 40% hydrogene peroxide and water resp. The normal trade solutions we get here in Norway is "Raw hydrochloric acid" - as sold for cleaning up concrete spill. The hydrogen peroxide I buy atthe chemists is listed as 30% strength. Making mix of diluting the raw acid 50 % gives a well controlled etchant.
NB: REMEMBER THE SAFETY RULES WHEN DILUTING ACID: ACID INTO WATER! NEVER WATER INTO ACID!

In our machines , I use sodium persulphate, - appx 250 g to the liter, but this mix must be heated to appx 45+C to work correctly. Ferric chloride is also OK- you just have to choose- ferric chloride stains everything, clothes included. Sodium persulphate just makes holes in your clothes!
( but when you notice the holes , it's too late )

[Structo]

Dang I got the chem 101 backwards......corrected now.

Yes I use the muriatic acid for washing stone.
It's hydrochloric acid but I think it is dilluted some.

Not sure what strength the over the counter hydrogen peroxide is.

[martin manning]

Drug store (chemist's, across the pond) H2O2 is 3%, and muriatic acid as sold for cleaning masonry is 28% HCl acording to the Gootee site. I'm picking some up today so I'll see what I can get.

Edit: The muriatic acid available locally is 31.45% (10.2M)... must be some variation in the exact strength sold among manufacturers.

Aurora, thanks for the info on your process- good stuff!

Re mixing order, I learned this rhyme as a child:

"May his rest be long and placid. He added water to the acid."

MPM

[ic-racer]

Not ideal, but I was able to make up a board by epoxy laminating some Wilsonart samples. The Wilsonart material is cheaper than Formica. The wood graphic is very thin and easily scrapped off, and it is thinner than Formica. I wouldn't think this stuff would be very durable as a countertop.

Anyway, it was free.