Going to start rolling my own PCBs soon-a few questions

[ExpAnonColin]

Here is a walteresque list of questions... I am going to use the laser printer onto avery paper/ironing/ferric chloride method.

1) I went ahead and bought some board from Radioshack because I'm impatient.  Was this stupid?  Where can I get board of different colors, like the really cool green?

2) Is there anything safer, or less generally evil, than ferric chloride, assuming price is no big deal?

3) Is there any way to do a DIY solder mask?  This would be super cool...  Does spraying it with polyurethane varnish help?

-Colin

[NaBo]

Well, I'm by no means an expert, but I've read a bunch about pcb etching when i was starting out, and i've done two pretty successful batches so far...  I'll give you a response if for no other reason that the forum is usually kind of dead and this ungodly hour. (for me anyway... 5:30 am  :shock:)

1) a. Well, it wasn't stupid.  The first batch I did was using the radioshack PCB kit... two smallish boards, a sharpie, ferric chloride, rubbing alcohol (to remove sharpie from traces after etching), and the plastic case doubled as the little etching bath.  This was a good, simple way of finding out if i was up to etching my own boards right from the get-go, but, like most things at radioshack, it's not cheap (about 20$), and not the best quality.  And the double sided boards weren't good at all for etching single-sided projects, since the back would take forever to etch.  After learning a bit more and getting more interested in this as a hobby (more like a way of life ), I took a stroll to a local electronics store and found some pretty big sheets (about 5" x 14")of single-sided copper clad for about 60 cents each.  They also sell bags of ferric chloride POWDER pellets, for 5 bucks... enough to mix with about a litre of water, and you can of course reuse the solution if you have a suitable container to store it in.  Used an old pyrex baking pan on a stovetop set to lowest heat, and it was completely etched in about 15 minutes.  Where I had the patience to get a good thick layer of sharpie (i was in a rush to etch and drill while home before having to head back to school), the results were flawless.  With the laser printer/ironing method, you should get perfect results.  So basically, radioshack is convenient for a test-trial, but it's a bit of a PITA to etch, and more expensive than it should be.

  b.  Dammit!  There was a thread about the different coloured circuit boards with a link (i think?) a while ago but the search function is failing me...  I think it may have possibly discussed Cornish and his red ones.  I'd like to know myself where the red and blue pcbs can be getted... cuz thats always cool.

2.  Safer for the environment, plumbing, or you?  There's a bunch of alternatives which i haven't used...  i've heard "muriatic acid" a lot.  I've heard of hydrochloric being used as well.  I imagine finding something "safe" in all three of the aforementioned categories that corrodes metal and other materials for a living is hard to come by  

3.  a) Not sure of that... never bothered, probably never will... though it is nice and sure looks professional.  A quick google turned up this product: http://www.mgchemicals.com/products/862.html.

    b) Probably any decent finish would do well to protect bare copper.  I opt to run a tinned iron over the traces...  takes time and looks kinda crappy, but i end up confident i dont have any broken traces, able to mod things in the future easily enough, and I know my copper won't be oxidizing in the meantime.  For someone like yourself, who is, i imagine, doing production runs and selling a finished product to the discerning musician... i mean... experimentalist .... the bare solder joints for modification isn't paramount and some type of lacquer or varnish sloshed onto the trace side after soldering would save time, cut costs, and perform the same protective function as a solder mask.  It's up to you in the end, perhaps someone more experienced could give you better advice regarding those methods.

So, it's not exactly the super-knowledgeable answers you deserve, but it'll have to do for now.   :wink:  

Good luck with the DIY PCB's!  May your etch resist never fail, your traces be contiguous, and...  your ferric chloride never spill on your stove while cooking some boards  

[rubberlips]

From memory, the different coloured PCBs are just sprayed that colour, as were the green ones for years and years and years. I thought it was justa different coloured laquer.

Anyways, I've been doing PCBs with the avery labels for years and it's pretty simple and works really well (although they dont have to be avery labels, any label backing with a none sticky surface will work. The only thing, be careful when putting it on the hot PCB. If you're not right on, the toner will stick  and then you have to print again

As for etchant, I think you can use something called amonium  something or rather (sorry can't remember the full name). I've got a bottle in the shed but it's too late to go out there - monsters come out at night  :twisted: I normally just use ferric chloride which does boards even if its a bit cold, just wait a bit longer.

You could solder to the tracks, I just whack a coat of PCB laquer over them to protect, still have a can from 10 years ago and still going strong.

Pete

[Samuel]

The alternative etchant is ammonium persulfate I believe. I think it's kind of a decision whether you want your etchant to stain your clothes brown or bleach them white. Beyond aesthetics I know many people prefer the ammonium because it is transparent and you can monitor the board's progress - (I've only ever used ferric).  One disadvantage (if it's even a disadavantage to you) is that the ammonium does not come in liquid form - you have to mix it.  (although reading the prev. response maybe you can find it in liquid? i've only ever seen powdered...)

And a big second "boo" on the RS boards, simply because if you are not making a double-sided PCB the backside of copper will take a long time to etch and exhaust your etchant for no good reason...

[nightingale]

Colin,
i used to get the "cool green baords" from steve @ smallbear. te ones he has shipped to me in the last year or so, have all been this slightly yellowish color. which is cool, i think that it sort of looks like "fish-paper" that was in older amps. in other words it looks old!

now i order this clear/translucent board from mouser. here is the part #: 501-FR4X6S

hth,

[Mark Hammer]

The colour of boards is not simply an aesthetic difference.  The milky green boards are made of fibreglass and are generally stiffer.  That can make one helluva difference in their susceptibility to cracks in traces due to bending.

Personally, I can't point to any specific standards, but my guess is that if you are making a board bigger than maybe 2" x 3" board composition can start to matter.  Think of this analogy - if the bar is short enough, it is difficult to bend; the thicker the bar, the longer it needs to be before it becomes bendable.  Nice thick fibreglass board can withstand manhandling without cracking thin traces.  That thin beige textured stuff can withstand manhandling if it is a small enough board, but if you're attempting something big there is greater risk of cracking traces.

As for ammonium persulphate, it is more than just a question stainig.  Ferric chloride, while it can be easily deactivated with baking soda, is worse for the environment and certainly harmful to your household plumbing, if unceremoniously dumped down the drain.  Ammonium persulphate is apparently less intrinsically harmful.  It also needs to be heated to work, which may be one of the reasons why some folks find it a nuisance to use but also why you can flush used stuff without automatically eating away your plumbing.

As for ferric chloride pellets, make sure you can store them in a DRY place.  I foolishly stuck mine on a shelf in the garage over the winter and I may as well have used rabbit droppings to produce etchant when the winter was over.

Heat helps in all etching processes, regardless of chemicals used, but there are an infinity of ways to apply that heat.  One thing I like to do is drill tiny holes at the corners of the board and stick toothpick pieces in to turn the board into a mini coffee table, copper side down.  This assures the board never sinks, and sit atop fresh-er etchant (used stuff sinks to the bottom).  With the component side of the board close to the surface of the etchant bath, you can simply blow warm air at it with a hair dryer or heat gun, or stick a reading lamp over it to warm it up.  As far as the board is concerned, all that really matters is that the molecules of etchant in the immediate vicinity of the board, and the board itself, are warm.

This last part cannot be overemphasized enough, and you will find many thousands of words on the topic in the archives: THE BEST ETCHES ARE PRODUCED WITH BOARDS THAT ARE PRISTINE AND SPOTLESS, BUFFED TO A MIRROR-LIKE SHINE BEFORE EVER TOUCHING ETCHANT.  How you accomplish this is your own business, but if your board, no matter what it is made of, has fingerprints, breath, or any source of oxidation or residue covering the bare copper, expect an awkward uneven etch.

[Peter Snowberg]

1) I went ahead and bought some board from RadioShack because I'm impatient.  Was this stupid?  Where can I get board of different colors, like the really cool green?

Forget the RS board.... as noted.... double sided is not good here.

The color comes from the solder mask almost 100% of the time. The exceptions are in phenolic board which is very poor quality in comparison to epoxy-glass board like FR-4. Fiberglass board is more of an epoxy cream-yellow color.

2) Is there anything safer, or less generally evil, than ferric chloride, assuming price is no big deal?

What's evil is the dissolved copper in the etchant.

Good commercial board houses recycle the etched copper and use it to electroplate the raw boards before etching to get thicker traces, to fill in manufacturing voids that would otherwise render the new board useless, and to create a very clean and pure surface for the photo-resist to stick to.

3) Is there any way to do a DIY solder mask?  This would be super cool...  Does spraying it with polyurethane varnish help?

You would need top spend more than it would cost a board house, you need full scale & high resolution silk-screen printing capability, and you would have a VERY hard time dealing with the chemistry. Commercial solder masks are mostly done with photo-imageable chemistry now.

Spraying things with varnish may be OK, but now you're talking about conformal coatings and not a solder mask.

The whole purpose of solder masks is to allow for automated wave soldering.



I don't mean to be disrespectful at all, but I've been making boards since before you were born and I've analyzed the situation in depth. Home made PCBs cannot hold a candle to commercial PCBs. That's just the way it is.

Best to save "rolling your own" for them twisty little cigarettes.

[onboard]

b) Probably any decent finish would do well to protect bare copper.  I opt to run a tinned iron over the traces...

I've seen a product called TinnIt that does just that. Could you use that *after* you etch, to tin the traces?

Colin, look around Parts Express in the hobbiest/prototyping section for the copper clad boards too, not sure how their prices compare though. They also carry photo-resist boards (uber green) and developer.

There's also an etching solution at Dick Blick Art Supply they claim is nuetral and "the safest solution available for biting zinc or copper plates" I contacted them to ask if it will in fact etch clean (explaining the intended use for homemade pcb's)  and the reply was yes. Don't know if it's the same as ferric chloride - methinks no since it's sold as nuetral and safe? Might be worth a try.

Careful with the muriatic acid - its still 20% hydrochloric and still mucho nasty. My wife was applying a patina solution to a frame she guilded with copper leaf, and spilled some on the garage floor. Even at that small percent hydrochloric, it etched the concrete :shock: Is the Radio Shack ferric chloride the same as anything else? Has it been on their shelf since 1997, or does that matter?

Shoot, maybe *I'll* try etching boards...

[nightingale]

Home made PCBs cannot hold a candle to commercial PCBs. That's just the way it is.

This is true.
I pay pretty close attention to detail when i make my boards/boxes. I have been doing home PCB's for about 2yr. It is still a pretty common act for me to have to take out the sharpie and "touch up" where the transfer did not take for whatever reason. once the sharpie hits the board all of the "professional look" goes right out the window IMO.. i am sure there are flaws in my PCB routine that cause this.. but i am pretty darn carefull!

I feel like if i was going to be selling alot of boxes, i would have them made someplace else.. i always liked the idea of silkscreening or however they put the graphics on them too..

i am considering having my boards made locally at this hobby place..
hth,

[mojotron]

... I am going to use the laser printer onto avery paper/ironing/ferric chloride method.

Have a lot of patience with your self.... it may take a number of tries. Just remember not to etch until you have a really good toner transfer...

I never had a good experience with Avery label backing method... but I did use the Staples "Picture Paper" method for a while... long enough to look for someone to make my boards for me... But, then I tried PNP Blue, and realized that that PNP is the only way to go for this - that stuff is perfect! But, I think you have to try the other methods to appriciate it... Like I said... patience....perseverence....

1) I went ahead and bought some board from Radioshack because I'm impatient.  Was this stupid?  Where can I get board of different colors, like the really cool green?

That stuff is ok... I ussually get copper clad from Smallbear or Mouser... but, the RS stuff works too. I get my etchent from RS - the dude there always gives me the evil eye... like I'm making a bomb or something...

2) Is there anything safer, or less generally evil, than ferric chloride, assuming price is no big deal?

It's generally safe, just don't put it down any drains... I nutralize it with a few pennies when I'm done... It turns into harmless sludge... If you put your etchent tray in hot water while you etch you won't have to use that much - I generally etch 3-4 boards in the etchent I used to use for just one before I started heating it with really hot water...

BUT, do your first few without heating the etchent in hot water - you will need the extra time to learn/see how this works. There are always spots that are slow to etch - a good toner transfer will allow you to keep the rest of the board in the etchent a while longer to allow these spots to etch.

3) Is there any way to do a DIY solder mask?  This would be super cool...  Does spraying it with polyurethane varnish help?

I've done a lot of boards, never used tinit...., the electrons generally don't mind what color the copper turns... although, for soldering you do have to start with really clean copper... I just sand it with 220 grit after ..

Look at my post here http://www.diystompboxes.com/sboxforum/viewtopic.php?t=30754&postdays=0&postorder=asc&highlight=pnp&start=15 for the details of how I do my boards... I can make pretty much perfect boards with this method (using PNP) and it's pretty quick too...

[Mark Hammer]

Glossy paper is "good enough" for SOME things, and not nearly good enough for others.  Similarly, PnP is "good enough" for some things, but not nearly good enough for others.

I've used Tinnit, and while it certainly keeps the bare copper traces from oxidizing too much, do not expect it to provide a superhighway for solder flow.  If you want to prevent solder from bunching up, you will still need to either buff the board or apply some liquid fluz with a Q-tip or something.

[Stuart]

Regarding tinning boards, immersion tin chemistries contain thiourea.  Apart from being a hazard to your person (toxic and carcinogenic), thiourea is extremely damaging to the environment and should never be disposed of to drain.  

Apart from all that, immersion tin has rather a short solderable shelf life, so don't tin boards unless you intend to populate them soon after. YMMV of course...

[puretube]

whatever you use/etch: "spaghetti"-layouts need much more etchant, and are more un-ecological, than largely ground-plained boards with small distances between traces!
Get more shielding, faster etching, longer-lasting poisons by blackening your layouts!
(this goals for most stompbox worx - radio hams know how to do it their way...).

watch out where the etchers go: DON`T you drain that yellow flow...

DON`T flush the blue p*ss either!

[Samuel]

on that topic - how great is the risk of heterodyning or any other issues if you essentially "fill in" the unused area on a board? is heterodyning the wrong term here? just curious...

[ExpAnonColin]

Wow, thanks for all of the responses.  I think I will go with the ammonium and boring old fiberglass boards and no solder mask...  Fortunately I have some micromesh (have you guys heard of this?) which is fiberglass sandpaper material that goes up to 12,000 grit... so I can definitely get it to a mirror.  I would get PnP but it's pricey...

Or maybe I'll just go back to pad per hole for everything but production runs :shock:

It's just that I get impatient... and when I have a design ready to be made into a PCB I don't want to spend tons of money and time waiting for it to come to my door, however gorgeous and wonderful (peter, I definitely respect what you say) it is.

-Colin

[puretube]

"heterodyning" is not such a risk in stompboxes;
what you`re worried about is rather (pos.) feedback;
large groundplaines can prohibit this,
but of course, on the other hand there`s a chance of "loading"
a (high impedance-) circuit at certain points through stray-capacitance (e.g. to ground);

experience and comparing/looking at other layouts can help a lot:

...ahh, err, and then again: traditonell stompox PCB layout isn`t exactly a good teaching basic... (sorry).

[Peter Snowberg]

Hey Colin, have you tried Veroboard yet?

Aron sent me a couple of pieces and I've got to say that I REALLY like it! (Thanks again Aron!

Zachary did all his early production that way. :shock:

[Apehouse]

I get my etchent from RS - the dude there always gives me the evil eye... like I'm making a bomb or something...

Yep, i've gotten that look too and i'm a fairly straight looking dude.  And a couple months back i had my kids with me at a local electronics store getting etchant and the dude there a super wierd look on his face(deer in the headlights) and kept looking at my kids. He eventually made a coment about it being poison and all. I must look like an idiot or a degenerate and i'm not sure which i prefer.  (My first response was to tell him how cool it made the purple in the grape kool-aid look, but i've discovered once you have kids you're not allowed to make those type of jokes in public anymore.)


I personally like the ziploc baggie method for etching(which i of course learned about rummaging thru these wonderful archives). I get the little "snack" size bags, drop in the board, add a wee bit of etchant, work quite a bit of the air out of the bag while closing it(i usually double bag it), and drop it in hot water. Only takes a few minutes but i have to work the etchant around in the bag with my fingers pretty frequently. Its seems to be the cleanest and quickest method for a lo-fi like me.  

hope it helps!
 -greg

[ExpAnonColin]

Hey Colin, have you tried Veroboard yet?

Aron sent me a couple of pieces and I've got to say that I REALLY like it! (Thanks again Aron!

Zachary did all his early production that way. :shock:

Yeah, but I much preferred Pad Per hole... no offense to the veroboardists, but I just like to have complete control.

-Colin

[Dan N]

I love this stuff!

http://www.web-tronics.com/printed-circuit-board-supplies-positive-photo-resist-pre-sensitized-pcbs.html

El YOU VEE