D
1: Your paranoia is warranted. imho.?
I too embarked on a DIY Etching setup which included the whole buffet of parts chemicals and storing them.
?After storing the chemicals in a explosion proof cabinet. +/- 6 months later? rust started to appear in the cabinet.
quite a bit of rust. While in my scenario Im not to happy that my once pristine cabinet in now full of surface rust. I am happy?
that its not my machines or the both of them! If you have valuable rust free machines? invest in storing the caustic chems properly.
-Sam

On Tue, 5 Mar 2019 13:05:18 -0600, you wrote:

After seeing some guys post on leaving his etchant tank out in his shop,
and the next day his drill press post was solid rust... I was thinking
that I really don't want to mess up my steel building or anything in it.
That said, if I use the muriatic/peroxide etchant outside, and then pour
it into a sealed container, I should be ok?

Define "sealed".....

Or if not if I really want
to be sure, what is the best of the other etchants that works the
fastest with no worry of rusting my stuff? Or am I being too paranoid?

Likely ammonium persulfate or ammonium perchloride. That still will
release extra oxygen here and there, but not acid fumes, afaik....

You could put it in a jug, say one used for distilled water or the
same one used for the acid (if you know someone who uses pool acid,
see if they have an old empty bottle.

I was tempted to (and almost did) get one of those brown resin
containers to put the acid in (suitably bottled).

No, you are not being too paranoid. I'd store it outside. I suspect
that the main problem is the fumes from the acid, but then again, no
idea of how well the container was sealed.

what would work should be a bottle designed for acid storage, say from
a chemical supply store.

Harvey

Thanks

Received from Harvey White at 3/5/2019 04:22 PM UTC:

The Ferric Chloride eventually becomes CuCl, but will run out of Chloride, hence adding HCL is needed. In the HCL/H2O2, you start out with enough oxygen from the H2O2, run out of that, then bubble. You really ought to bubble in the first place, since it keeps the etchant moving.

Exactly!

And using just plain CuCl + HCl, with no iron present, avoids the brown color the iron imparts to the solution so it's much easier to tell when the solution needs rejuvenating by bubbling. Emerald green is good, muddy brown is bad. Somewhere in between etches just fine, but most will prefer to maintain emerald green.

Jim H

Received from Rob via Groups.Io at 3/5/2019 03:23 PM UTC:

My experimenting with HCL H2O2 was driven by a 2 decade old Radio Shack Ferric Chloride failure to etch:

That looks like you either used spent FeCl or didn't etch long enough. You'd get the same result from using spent HCl/H2O2.

Jim H

Received from Dave at 3/5/2019 05:21 PM UTC:

On 3/5/2019 10:28 AM, Harvey White wrote:

On Tue, 5 Mar 2019 08:26:04 -0600, you wrote:

Thanks. I had found that one earlier today. It has been replace by a more expensive model. After a lot of searching online, it looks as though I just need to look for a suitable container, get a pump, and a heater. The proper shaped glass vase or something. Glass is better. The etchant tends to eat the seal on rubbermaid containers, but will work. You could use an air bubbler stone, but that will be attacked by the acid. At one time, I used an aquarium heater to heat the etchant, from what I remember, I stopped that and just etched on warm days.

Ammonium persulfate (or perchlorate) does not corrode things the way that HCL based etchants do.

Ammonium persulfate solution needs to be heated to etch efficiently and heat causes the solution to decompose. It isn't as efficient at etching copper as other more easily obtained chemicals unless the solution is enhanced via the addition of a trace of mercuric sulfate. That's a really big NO NO for anyone without the ability to manage the waste100% legally. Whether or not heated, the solution can't be rejuvenated and must be disposed of when spent... along with any copper it contains. No problem for those who don't care about proper (legal) disposal... a pain in the butt for those who do. I'd forget ammonium persulfate.

Ammonium perchlorate sounds similar to ammonium persulfate, but it's a completely different thing. It's a super powerful oxidizer with primary uses being in fireworks and as an ingredient in some solid rocket propellants. I can't find any credible references to using ammonium perchlorate for etching PCBs. The chemistry just isn't right.

Use polypropylene or glass and corrosion becomes a non-issue. Note that the material in the soft seal built into the lids of some polypropylene containers isn't polypropylene and could be attacked. That's why I store my solution in a large wide mouth glass jar with a plastic lid left a bit loose to avoid pressure build up.

I was just looking at those 8x8 inch square glass blocks as an easy container. The ones that have the rectangular hole already cut in them. May make a good starter bubble tank. So now I already have my first problem. Finding a plastic suitable for my HCL based etchant. :) Or change etchants already... I want to stick with the muriatic and peroxide for now.

When it comes to plastic containers, pretty much any polypropylene container from Walmart will do for etching. No lid needed when etching. The recycling symbol for polypropylene is a recycling triangle with "5" or "05" inside and "PP" below, so it's easy to identify. I etch in a plastic pan and store the solution in a glass container with a plastic lid between uses. I use a large 1-gallon or so wide mouth jar that's about half full... and the bubbler tube comes out thru a small hole in the lid... so when bubbling to rejuvenate my solution any minor splashes from the bubbler stay in the jar. If you just use HCl and peroxide and don't let copper build up appreciably in it, there's nothing to rejuvenate so you can forget the rejuvenation part. (But leave the lid a bit loose because H2O2 decomposes to produce oxygen gas and that can cause pressure to build up.) I actually added a fair bit of copper wire to my initial HCl/H2O2 solution because I wanted to let the cupric chloride that forms plus a bit of HCl do the etching... and I rejuvenate the solution with bubbled air rather than adding H2O2. Using this approach the only thing you add is a bit of water to maintain the volume of the solution and a bit of HCl when the solution won't rejuvenate completely to a nice emerald green. That boils down to adding HCl in the amount needed to make up what gets used when etching... and that's not much unless you etch a heck of a lot of boards. It's adequate to just etch until the solution either won't rejuvenate to a bright emeralds green or if you notice that the etching rate is slowing down. I've never noticed the latter.

Also, a fritted glass bubbler is NOT affected by the etchant. Stone bubblers (as warned above) maybe, depending on the material, but NOT fritted glass. Fritted glass bubblers are a glass tube with a porous glass bubbler on the end. The stone type will almost always have a plastic tube with a bubbler stone glued/epoxied onto it. The smallest (cheap) vibrating aquarium pump will provide enough air for etching and rejuvenating. You don't need a sheet of bubbles flowing vigorously all over the board, you just need the solution moving around enough to continuously remove the brownish reaction products from the surface of the board. The more you agitate the solution the more undercutting you'll get so a large airflow isn't as desirable as one might think.

To it in perspective, you have to etch a heck of a lot of boards to put the slightest strain on a couple of liters of etchant consisting of cupric chloride solution plus HCl.

Jim H

On 3/5/2019 12:42 PM, Harvey White wrote:

On Tue, 5 Mar 2019 08:44:41 -0600, you wrote:

Harvey,

?5-6 minutes on the tin. I can remember that. Never heard of a
"microinch" though. :)

Instructions are on the MG chemical site.

One milionth of an inch. Yikes! That is thin. I never get anything closer that 0.0005 :)

No photo trays but plenty of dog treat plastic containers. Square ones
too. Never too clean is the rule.

Just never reuse them, of course.

Of course.

Ni vias for me yet until I get going and see the need. I have two
granite tables but the marble slabs are likely almost as accurate for
being flat.

Vias are good when doing double sided. No real use otherwise. You
can use jumpers as needed to jump traces. On a double sided board,
the jumpers are replaced by traces, of course.

I bought either marble slabs or regular tiles. The advantage on
double sided boards is that the epoxy doesn't really glue the tiles
together. Make sure that the board surface is covered with masking
tape to avoid bleed through on the epoxy. That's for double sided
boards, of course.

That is one way and a good idea for a double sided board.

And I just got a new portable vac with my free bonus points from a
credit card company and got a Lowes gift cad for Xmas.

You can run a hose from that to the drill press and suck up the
debris.

I have a industrial hood/mask thing with an air pump if I need to get
serious. I used it for sandblasting outdoors.

that'll work too, but the vacuum cleaner is good, mine has a HEPA
filter and was intended for this use (originally, CNC milling of
boards).

Harvey

In the end it's all about safety and health. And I plan on being healthy as long as I can. :)

开云体育

On Tue, 5 Mar 2019 08:31:05 -0600, you wrote:

Harvey,

? All good info. 

Thanks.

If I ever come up with a money making idea with a pcb 
board involved, I may have to have my boards made, But I don't ever see 
that happening. 

Make sure that you can legally do this with the PC board package you
have.  EAGLE and other "free" versions have a "no profit" restriction.

DesignSpark has no restriction. I don't think Diptrace does either but I would have to verify that.

Who knows, maybe in a time saving way if the price was 
right, but I need to be realistic as I have many other interests/hobbies 
that need some of my time. :) 

Not that I'd know anything about that...........

:):):) I was told once that my hobby was "collecting hobbies".

That said, when I decide to do something I 
go all out to do it the best I can so all this info is great. I am going 
to use Muriatic and HP for my etchant for now.

I started out many years ago with photoetching, KPR and Kodalith
negatives.  Photo stuff was fine, the KPR was nasty stuff.

I tried some presensitized boards, with varying results, negative
density is absolutely critical.

Went to toner transfer, which has been working for a long time. Needed
double sided boards and ended up making each side and epoxying them
together.

However, the designs got so complex that I needed plated through
holes.  That ran the limit of what I could do at home.

Tried Oshpark (and they're very nice, good quality, price depends on
the size of the boards), then I tried a Chinese firm, somewhat
different boards, but not too much.  Oshpark was ENIG (gold plated),
Chinese is HASL (Hot Air Solder Leveled).  Either works.

So I outgrew, if you would, what I could do at home.

Good luck on your projects.

Harvey

You likely did much more than I even plan to accomplish. Small and simple for now.

开云体育

I was stunned by the OSHPARK price and service.

????? says MADE IN THE USA

and when I pulled the trigger and paid $60 for 3 small circuit boards

they said my order was ready for a fabrication house and I will be informed when they have added my

3 PCBs to a huge sheet of orders... and

a day later they said? GOOD NEWS...YOUR GERBERS ARE ON THEIR WAY TO A FAB HOUSE... WE WILL LET YOU KNOW WHEN YOUR

PCBs RETURN FROM THE FAB HOUSE

and then

two weeks later? I got my PCBs that I thought OSHPARK was going to make in the USA.

and then

I spent $13 buying ten PCBs from ALLPCB.com and they were done and delivered in FIVE days.

Needless to say I will never use OSHPARK again.

After seeing some guys post on leaving his etchant tank out in his shop, and the next day his drill press post was solid rust... I was thinking that I really don't want to mess up my steel building or anything in it. That said, if I use the muriatic/peroxide etchant outside, and then pour it into a sealed container, I should be ok? Or if not if I really want to be sure, what is the best of the other etchants that works the fastest with no worry of rusting my stuff? Or am I being too paranoid?

Thanks

开云体育

Hi Rob,

? Funny thing you mention the rocker as Many years ago I bought some slow rotisserie motors to build a rocker and still have the parts. I was going to make a wooden cam lobe and have the tupperware container on a small wide see-saw where the wooden cam would move the board up and down. I know I don't "need" a bubble tank but I think it would be pretty nice to have.

Thanks

On 3/5/2019 11:57 AM, Jim Pruitt wrote:

Hello Dave

On 3/5/2019 9:21 AM, Dave wrote:

Glass is better.? The etchant tends to eat the seal on rubbermaid

containers, but will work.? You could use an air bubbler stone, but
that will be attacked by the acid.? At one time, I used an aquarium
heater to heat the etchant, from what I remember, I stopped that and
just etched on warm days.

Ammonium persulfate (or perchlorate) does not corrode things the way
that HCL based etchants do.? I've seen designs that are effectively
spray etchers, rotating cylinders with holes in them.? Normal water
pipes (schedule 20 or so) do not get affected by the acid, so an "L"
of that plastic with small holes drilled in it, fed outside by an air
pump will handle the bubbler.

Your tank needs to be level for a good bubble flow.

Harvey

I was just looking at those 8x8 inch square glass blocks as an easy container. The ones that have the rectangular hole already cut in them. May make a good starter bubble tank. So now I already have my first problem. Finding a plastic suitable for my HCL based etchant. :) Or change etchants already... I want to stick with the muriatic and peroxide for now.

The DIY etch tank I referenced in Radio Electronics Magazine for December 1989

?had you buying acrylic (aka Plexiglass) sheeting and cutting it to the sizes you needed. Then using a solvent glue (WeldOn #3 or #4--or acetone works too I think) and gluing the container together.? It also had you build a carrier so you did not have to fish the board out of the warm etchant.? It used fish tank air pumps and fish tank heaters.? I think places like McMaster Carr have the solvent and probably the plexiglass or if you have a local plastic shop (maybe a sign shop) often have it and will even cut the size(s) for you for a fee, at least the plastic shops. Also places like Ace Hardware and to a much lesser extent Lowes and Home Depot have acrylic but usually not the 1/4" (6mm) thick that was used in this article.

I liked that arrangement because it allowed me to make several tanks the size I wanted or needed.

Good luck.

Jim Pruitt

Hi Jim,

? I just answered the other message about the Radio magazine instructions so disregard that one. I will call a few sign shops and see what they say and also check out McMaster Carr.

Thanks

I dont have plans. because I "winged it" But your free to copy mine. Im 100% satisfied with my setup.
https://www.hyperlinks.net/?s=etching&id=m

On Tue, 5 Mar 2019 13:01:53 -0500, you wrote:

NOT saying DO NOT build a heated bubbler etching tank ......

but

for any newbies doing it for the first time........

you don't need heat or bubbles.

agitation with new HCL and H2O2.

Once it becomes CuCl then you need agitation. Heat will speed up
etching.

agitation tends to remove "stale" etchant near the board.

When you brush the board with etchant using a sponge, you remove the
oxidation and don't need agitation.

I've been etching for 4 years on my kitchen counter at room temperature
and in summer in 65 degree crisp cold air conditioning

and

never have seen any deviation in my HCL H2O2 etch bath time.... always
between 5 and 7 minutes

That tends to indicate fresh etchant every time. Since I use a tank,
I needed to keep the solution for a while, ended up with about a
gallon capacity tank, so different approach.


Harvey

and

I periodically wipe bubbles off the copper with a fan shaped makeup
brush and make sure that the metal

ferule on the brush never touches the liquid.

Some guys use rockers to slosh the liquid.

Some guys attach vibrator motors.... the kind in pagers and cell phones
and kink toys...

?to shake away the bubbles that form on the PCB.

?Sometimes I don't even bother with the brush

and

always end up with a pretty PCB.





On 03/05/2019 12:21 PM, Dave wrote:

On 3/5/2019 10:28 AM, Harvey White wrote:

On Tue, 5 Mar 2019 08:26:04 -0600, you wrote:

Thanks. I had found that one earlier today. It has been replace by a
more expensive model. After a lot of searching online, it looks as
though I just need to look for a suitable container, get a pump, and a
heater. The proper shaped glass vase or something.

Glass is better.? The etchant tends to eat the seal on rubbermaid
containers, but will work.? You could use an air bubbler stone, but
that will be attacked by the acid.? At one time, I used an aquarium
heater to heat the etchant, from what I remember, I stopped that and
just etched on warm days.

Ammonium persulfate (or perchlorate) does not corrode things the way
that HCL based etchants do.? I've seen designs that are effectively
spray etchers, rotating cylinders with holes in them.? Normal water
pipes (schedule 20 or so) do not get affected by the acid, so an "L"
of that plastic with small holes drilled in it, fed outside by an air
pump will handle the bubbler.

Your tank needs to be level for a good bubble flow.

Harvey

I was just looking at those 8x8 inch square glass blocks as an easy
container. The ones that have the rectangular hole already cut in
them. May make a good starter bubble tank. So now I already have my
first problem. Finding a plastic suitable for my HCL based etchant. :)
Or change etchants already... I want to stick with the muriatic and
peroxide for now.

On Tue, 5 Mar 2019 08:49:20 -0600, you wrote:

Yes, CNC rules. I have a few 3D Printers. I though about CNC'ing (is
that a word?) my mill but then I figured I would want handles on it too
for manual work as everything in CNC would likely not be a great idea.
Most of the CNC mills seem to lack the handles or maybe I didn't look
hard enough but I know turning a stepper motor can mess up some
controller boards as they generate voltage when you do that and back
feed the board.

You could always disconnect it (power off!!!) and disconnect the
motors. You'd want dual shaft steppers. I do think it depends on the
drivers, though.

Some drivers can be disabled, and the drivers may be happy with
voltage induced on the leads. The main problem is that the inductive
spike when disconnecting with power on will spike through the driver
transistors.

Harvey

On 3/4/2019 8:25 PM, Harvey White wrote:

On Mon, 4 Mar 2019 17:39:37 -0600, you wrote:

Harvey,

? Yes, all good info. My Proxxon just arrived so I will been opening
the little box and see what I bought. :)? I figure 8500 rpms will be
fine and being it's a hobby I will be ok. I have a large milling machine
and learned a lot from using it. Too bad it isn't CNC. :)

One of these days, I'll complete the CNC conversion on my X1...

Harvey

On Tue, 5 Mar 2019 08:44:41 -0600, you wrote:

Harvey,

?5-6 minutes on the tin. I can remember that. Never heard of a
"microinch" though. :)

Instructions are on the MG chemical site.

No photo trays but plenty of dog treat plastic containers. Square ones
too. Never too clean is the rule.

Just never reuse them, of course.

Ni vias for me yet until I get going and see the need. I have two
granite tables but the marble slabs are likely almost as accurate for
being flat.

Vias are good when doing double sided. No real use otherwise. You
can use jumpers as needed to jump traces. On a double sided board,
the jumpers are replaced by traces, of course.

I bought either marble slabs or regular tiles. The advantage on
double sided boards is that the epoxy doesn't really glue the tiles
together. Make sure that the board surface is covered with masking
tape to avoid bleed through on the epoxy. That's for double sided
boards, of course.

And I just got a new portable vac with my free bonus points from a
credit card company and got a Lowes gift cad for Xmas.

You can run a hose from that to the drill press and suck up the
debris.

I have a industrial hood/mask thing with an air pump if I need to get
serious. I used it for sandblasting outdoors.

that'll work too, but the vacuum cleaner is good, mine has a HEPA
filter and was intended for this use (originally, CNC milling of
boards).

Harvey

Thanks

On 3/4/2019 7:20 PM, Harvey White wrote:

On Mon, 4 Mar 2019 16:46:21 -0600, you wrote:

Harvey,

? I am a very careful person but I do appreciate the warnings
nonetheless. How thick is the correct amount of plating?

Not very, I think it works out to (and check the MG chemicals website)
5 microinches/minute. I remember leaving the boards in for about 5-6
minutes, which is what they recommend.

I used old photo trays, 5x7 or 8x10 were fine, and the plastic was not
attacked by the chemicals. You'll want a dedicated funnel for the
bottle, too.

While the solution has "brighteners" in it, that remove airborne
induced oxidation, the cleaner you get often the better.

When I did double sided boards, I could not have any vias under a part
(except a dip socket), but had to place them outside of any part.

I used #26 wire to "lace" the top to the bottom at the vias, soldered
both sides, then carefully clipped the excess off.

I also made the top and bottom separate, and aligned them (it can get
tricky) and used 30 minute (not 5, think about it....) epoxy to put
the boards together, and fairly stiff pins to align them. I had
masking tape on both copper sides (keeps epoxy fingerprints off...),
used gloves, and used tape to hold the boards in alignment before I
put the sides together. Putting it between two slabs of marble (home
discount store cheap stuff), made the whole board turn out flat.

Once done, remove the tape, trim to size (I use a shear), and then
drill.

Better to use a vacuum cleaner sucking in the debris than blowing
fiberglass dust into the air.

If you can find someone with a CPAP unit, the old hoses can be useful.

Harvey

On 3/4/2019 3:25 PM, Harvey White wrote:

On Mon, 4 Mar 2019 13:38:34 -0600, you wrote:

Please read the warning labels, do this outside, and do not breathe
the fumes.

Time in bath equates to thickness of plating.

Solution can be reused many times until it fails.

Harvey

On Tue, 5 Mar 2019 08:31:05 -0600, you wrote:

Harvey,

? All good info.

Thanks.

If I ever come up with a money making idea with a pcb
board involved, I may have to have my boards made, But I don't ever see
that happening.

Make sure that you can legally do this with the PC board package you
have. EAGLE and other "free" versions have a "no profit" restriction.

Who knows, maybe in a time saving way if the price was
right, but I need to be realistic as I have many other interests/hobbies
that need some of my time. :)

Not that I'd know anything about that...........

That said, when I decide to do something I
go all out to do it the best I can so all this info is great. I am going
to use Muriatic and HP for my etchant for now.

I started out many years ago with photoetching, KPR and Kodalith
negatives. Photo stuff was fine, the KPR was nasty stuff.

I tried some presensitized boards, with varying results, negative
density is absolutely critical.

Went to toner transfer, which has been working for a long time. Needed
double sided boards and ended up making each side and epoxying them
together.

However, the designs got so complex that I needed plated through
holes. That ran the limit of what I could do at home.

Tried Oshpark (and they're very nice, good quality, price depends on
the size of the boards), then I tried a Chinese firm, somewhat
different boards, but not too much. Oshpark was ENIG (gold plated),
Chinese is HASL (Hot Air Solder Leveled). Either works.

So I outgrew, if you would, what I could do at home.

Good luck on your projects.

Harvey

Thanks


On 3/4/2019 7:13 PM, Harvey White wrote:

On Mon, 4 Mar 2019 16:43:20 -0600, you wrote:

Ok on the top/bottom posting. Nobody is complaining yet. :)

My default trace setting was 15 and I had bumped it up to 20 so that
sounds good to me. I have seen those "islands" you speak of and figured
it was either a ground plane or a way to save etching time. I may
experiment with that.

The island approach really didn't require etching, it needed an xacto
knife and a ruler.

Etching time will be the same, as long as you have enough etchant.
Think about that one, you have to go through the same amount of copper
regardless. When you do the etching, you'll want a bubbler of some
sort. The HCL/H2O2 etchant works very well until you run out of H2O2,
perhaps 30 days. The etchant then changes (slowly) into CuCl etchant,
which etchs when oxygen is added, literally, your first time look at
the copper and you'll see it turning reddish and going away, that's
the copper oxidizing in solution.

Once the etchant changes color, then you're likely in CuCl etching.
I'm not the expert, but an internet search may give you accurate (and
better than mine) details.

For the mechanical approach, you could also use CNC and some sort of
router bit (usually PCB and carbide). It works very well on discrete
transistors/resistors/capacitors but has a limited utility when
dealing with ICs... Has more to do with pin spacing than not.

Main thing is that you make boards that work for you. As you decide
to go from through hole to surface mount, and then to TFQP flatpacks,
and then plated through holes, your techniques will change until you
likely need to use a board house to make the designs. Mine did.

However, there's a lot you can learn in the process.

Harvey

I am using DesignSparkPCB for now.

I ordered the 16oz bottle of MG Liquid Tin. That should last me forever.
Good reasoning on why a lot of people don't use Tinit or Liquid Tin
because they finish soldering all the components right away. Now I can
plan ahead and etch, tin, and save for later finishing if need be.

Thanks


On 3/4/2019 1:45 PM, Harvey White wrote:

On Mon, 4 Mar 2019 11:31:38 -0600, you wrote:

Quick question. Is top posting preferred here. That is the way I like to
do it but on some other forums people complain and like it the other way.

I prefer to interleave where reasonable. For this post, I will. For
the previous post, it was so long that without seriously trimming it,
my reply would be at the very bottom.

You get your choice, I think.

Now back to the subject at hand...All good info but, if I am just
starting out and am not worried about trace widths, my job should be
easier if I use wide traces at first, right? I remember taking apart old
electronics and the traces and solder were absolutely thick. And for
starters my projects will be very simple, like a breakout board.

Generally about 16 mils is what I normally use. However, as long as
the traces work for you, and you can build the board, it doesn't
matter.

There's a method that makes the pads as large as possible, so you're
wiring parts between very large pads, islands, even. The 1/16 inch or
so is the space around the pads. Saves etchant and can be done with
an xacto knife in some cases.

I think I seen where Rob found that Krylon enamel paint was a great
resist that could be thinned with lacquer thinner and used in a pen.

Depends on how you do the board. I generally did a program (like
EAGLE), toner transfer, and then I tinned the board.

Does Tinit help any or is that just a corrosion preventative and does
anyone use it anymore?

It's a bit of a corrosion inhibitor, and is effectively solder, so it
makes soldering easier.

I've done boards both ways, and if you build the board all at once,
then you likely can get away without the tin/lead. What happens if
you don't is that you get tarnish from normal oxidation and soldering
becomes difficult.

If you could mask the pads somehow, you could do a solder mask with
paing, and that would allow you to have a neater board. That, with a
silk screen layer would be a good look.

What they do in the factory is use a solder mask chemical that's UV
cureable... The stencil has holes where the pads are, you coat the
entire board with the mask, let it dry, and then the UV through the
stencil destroys the polymer so that the exposed areas wash off,
uncovering the pads.

Hence the tinning that tends to make the board look good and reduces
corrosion.

Harvey

开云体育

NOT saying DO NOT build a heated bubbler etching tank ......

but

for any newbies doing it for the first time........

you don't need heat or bubbles.

I've been etching for 4 years on my kitchen counter at room temperature and in summer in 65 degree crisp cold air conditioning

and

never have seen any deviation in my HCL H2O2 etch bath time.... always between 5 and 7 minutes

and

I periodically wipe bubbles off the copper with a fan shaped makeup brush and make sure that the metal

ferule on the brush never touches the liquid.

Some guys use rockers to slosh the liquid.

Some guys attach vibrator motors.... the kind in pagers and cell phones and kink toys...

?to shake away the bubbles that form on the PCB.

?Sometimes I don't even bother with the brush

and

always end up with a pretty PCB.

Hello Dave

On 3/5/2019 9:21 AM, Dave wrote:

Glass is better.? The etchant tends to eat the seal on rubbermaid

containers, but will work.? You could use an air bubbler stone, but
that will be attacked by the acid.? At one time, I used an aquarium
heater to heat the etchant, from what I remember, I stopped that and
just etched on warm days.

Ammonium persulfate (or perchlorate) does not corrode things the way
that HCL based etchants do.? I've seen designs that are effectively
spray etchers, rotating cylinders with holes in them.? Normal water
pipes (schedule 20 or so) do not get affected by the acid, so an "L"
of that plastic with small holes drilled in it, fed outside by an air
pump will handle the bubbler.

Your tank needs to be level for a good bubble flow.

Harvey

I was just looking at those 8x8 inch square glass blocks as an easy container. The ones that have the rectangular hole already cut in them. May make a good starter bubble tank. So now I already have my first problem. Finding a plastic suitable for my HCL based etchant. :) Or change etchants already... I want to stick with the muriatic and peroxide for now.

The DIY etch tank I referenced in Radio Electronics Magazine for December 1989

?had you buying acrylic (aka Plexiglass) sheeting and cutting it to the sizes you needed. Then using a solvent glue (WeldOn #3 or #4--or acetone works too I think) and gluing the container together.? It also had you build a carrier so you did not have to fish the board out of the warm etchant.? It used fish tank air pumps and fish tank heaters.? I think places like McMaster Carr have the solvent and probably the plexiglass or if you have a local plastic shop (maybe a sign shop) often have it and will even cut the size(s) for you for a fee, at least the plastic shops.? Also places like Ace Hardware and to a much lesser extent Lowes and Home Depot have acrylic but usually not the 1/4" (6mm) thick that was used in this article.

I liked that arrangement because it allowed me to make several tanks the size I wanted or needed.

Good luck.

Jim Pruitt

开云体育

Hello Dave.

AmericanRadioHistory.com has scanned many old magazines including Radio Electronics.?


Look at Radio Electronics for December 1989.? The table of contents says page 45 but it actually is page 41, at least as far as Adobe pages go.? The direct link to the magazine (entire issue) is:

The article title was "Make Your Own Etching Tank" by Tony Lewis.

I built several of these after that article came out.? Why several, you ask.? Because it was easier to make a tank the size I needed so I did not have to have too much etchant open at any one time.? The size as shown in the article is a great size for these days but back then I was trying to make some large boards.? The WeldOn #3 or #4 solvent/glue is much easier to find these days than it was then.

Good luck.

Jim Pruitt

开云体育

But it was 2 decades old. :)