Etching at Home

[(In)Sanity]

I've tried and tried with the PnP blue over the years.  I've never got decent repeatable results.  However, one thing I've noticed is I get wildly varying results depending on the printer used.  From pretty good to zero transfer at all.  So I wonder if the large variation people have in success has something to do with which printer/toner is used.

Without a doubt,  the printer and brand of toner is critical.   So far I've had the best results with Konica/Minolta toner.   Now if I can just keep their printers running I'll be happier.

[Alana]

Double sided boards can be a bit tricky however. 

I did 2 sides with toner transfer - trick is to have common line between boards - i managed by cutting my board so that one of the edges was exactly the edge of ready pcb. This is unadvised with toner-transfer but allowed me to make both sides match.

Another thing is - i may use drilled holes as "fedushals" to match top and bottom. Basically - most of child-thinking ideas will work.

[ptricks]

The printer I currently use is an HP laserjet 2100 that replaced my laserjet 4. They are really old printers but do a superb job at printing. Caution, they do weight a lot as they contain lots of metal, that stuff that existed before all the plastic they use now
The one I have was made in 1998, has printed 900,000 pages and still works fine, I bought it on ebay, shipped for $40

I think the problem some are having with using an iron is the iron can be too hot and you cannot get enough even pressure.
With the laminator if the board is cold you need to warm it up doing multiple passes through the laminator with the sheet on it till you notice it start to stick, then do it a couple more times, the board will become too hot to hold so use a towel or cloth to hold the board. I run it through about 6 or 7 times turning the board each time. Might seem like a lot of time, but it really only takes a couple minutes.

For double sided boards I apply the first toner sheet to one side
Run the board through the laminator
Remove the paper
Drill 3 holes that will be used to line up with the second side of the board
Align second side of paper with the holes while holding the board over a light
Run the second side through the laminator, the toner already on the first side will not come off, the rollers are a special type of rubber that is non stick.
Remove the paper and etch. The holes are so small that over etching doesn't occur.

[Psi]

Double sided boards can be a bit tricky however. 

Yeah.

I've done it a couple of times and this is how i do it.

1 ) Toner transfer and etch one side (cover the copper on the other side with insulation tape. Be careful to make sure there are no ripples in the tape on the edges)
2 ) Drill out one through hole pad on each side of the pcb with the smallest drill you have. Make it as centered as possible, if you don't like the centering move to another hole and repeat.
3 ) Print out the toner transfer sheet for the 2nd side
4 ) With a sharp point puncher the sheet in the center of the matching pads
5 ) Put the pcb and sheet together using two drill bits or two bits of rigid wire as alignment pins to match up the sides.
6 ) Apply some super glue on the edges and when dry remove the alignment bits from step 5
7 ) Use Iron or laminator to transfer pattern to pcb.
8 ) Mask off the already etched side and etch the new side.

Note, you can etch both sides at once, but you need to be vary careful not to scratch the toner tracks when doing the other side. It's also harder with the alignment pins since you have to align both toner sheets at once.
Note, you need to mirror image one side so check this is correct before you start. (your pcb package may/maynot already do it)

[SgtRock]

Greetings EEVBees:

--At one time I was contemplating making my own PCBs, but I have been too busy doing repairs on friends stuff and dumpster finds. But I did to a lot of research and found the 4 part series of videos in the below link, which I believe to be the cleanest, best and most efficient approach to Homemade PCBs I have yet seen.

http://www.getlofi.com/?p=1997

--Please, any and all, have a look and tell us what you think.

"    'Tis a lesson you should heed:
    Try, try, try again.
    If at first you don't succeed,
    Try, try, try again. "
William Edward Hickson 1803 - 1870

Best Regards
Clear Ether

[free_electron]

I did try ammonium persulphate once but its no good for press-n-peel.

Try Sodium Persulphate instead. that's what the industry uses

[Harvs]

After reading this yesterday, I though I'd have another go.

Just want to say thanks.  After using a few of the techniques people talked about here, I've produced two small boards with PnP blue that turned out spot on.  I've never had that work like that before.

I think the biggest factor was pre-etching the boards.  The surface texture changes considerably and the toner/PnP stuck great.

[ee851]

wilfred, thank you for the tips.

.
.
..  One trick I learned for toner transfer is, after cleaning the PCB, drop the board in etchant until you see a solid color across the board surface,  once I started using the etchant rinse before transfer I never had problems getting the toner to stick and it worked for everything from normal printer paper to magazine paper.  . . .

ptricks, could you please elaborate on what you mean by this?
I am a newbie at toner transfer and don't understand.
This is on a cleaned copper-clad board before toner transfer, right?   What etchant are you using?

[smashedProton]

He means that you dunk the board before you transfer toner.  The theory is that it would roughen up the surface, so the toner would stick better.  Hope this helped.

[ee851]

Yes, thank you.     So if I dip the cleaned board in etchant, do I rinse the etchant off with water before applying toner?    Or do I wipe it off with an oil-free towel?

[SeanB]

Dip till an even matt appearance, then remove and rinse in clean water. Then dry with hot air, and do not touch it. Use surgical gloves and handle at the edges only. Apply toner within a few minutes or it will tarnish.

[smashedProton]

Do any of you guys tin/ solder plate your boards?  I have been looking into it, but A i cannot afford to buy the tin plating solution and B i do not know how to make it myself.  I was able to scavenge a giant bar of 63/37 solder one time.  I wonder if sulfuric acid and heat would do the trick... 

Is plating necessary for surface mount work?  Or can I get away with soldering the components directly after the board is done?

[(In)Sanity]

Do any of you guys tin/ solder plate your boards?  I have been looking into it, but A i cannot afford to buy the tin plating solution and B i do not know how to make it myself.  I was able to scavenge a giant bar of 63/37 solder one time.  I wonder if sulfuric acid and heat would do the trick... 

Is plating necessary for surface mount work?  Or can I get away with soldering the components directly after the board is done?

If the board is well cleaned before you start to solder with something slightly abrasive and some alcohol then you'll be good.   The trick to SMD is using flux,  without it your fighting a loosing battle.   Even regular paper can be used as an abrasive.    Cleaning and Flux are important parts. 

[ptricks]

Dipping the boards in etchant is really an important step. I first tried using things like brasso that are chemical copper cleaners and while they do make it look better they don't leave the copper with a surface that the sticks to the toner. My steps are:

Clean the board with a little soap and water.
Rinse well.
Apply the chemical cleaner, like Brasso.
Rinse well.
Drop board in toner until even color across the board, if you see patches or spots that don't clear up then clean the board again.  It can sometimes take a full minute for the board to get an even color. Depends on the etchant, I use mutiatic acid and peroxide.

A quick note about the etchant . You don't have to keep making new etchant. The batch I am using is several months old and has etched a lot of boards. When you are done etching, place the container in a safe area where nobody will contact it , with the lid OFF. In a few days you will see the etchant return to  the orginal light  green color vs the dark green. I don't know the exact cause for this but assume it is the liquid being exposed to air .  The more the etchant has been used the longer it takes to return to the light color.

If etchant  gets to the point where it can't be re-used you can do a couple things with it. One is plate out the copper, basically need a metal that can be plated with copper and a small voltage source, even 1.5V AA cells will work.  In solutions where there is a lot of copper just placing another metal in the solution will cause the copper to attach itself.

WARNING: DO NOT PUT ALUMINUM IN THE ETCHANT. IT WILL REACT VIOLENTLY.
The reaction is toxic and can cause the etchant to reach temperatures that will melt a plastic container.

If you want to store the etchant you can convert it to crystals that can be restored by adding some more acid. To make  crystals place the etchant on a heat source of low heat and evaporate out all the liquids.

[(In)Sanity]

I just use a mild scotchbrite followed by a good scrub with acetone.   I've never had toner not stick.  I'm sure the toner has a lot to do with it.

[Mark]

Do any of you guys tin/ solder plate your boards?  I have been looking into it, but A i cannot afford to buy the tin plating solution and B i do not know how to make it myself.  I was able to scavenge a giant bar of 63/37 solder one time.  I wonder if sulfuric acid and heat would do the trick... 

Is plating necessary for surface mount work?  Or can I get away with soldering the components directly after the board is done?

I used cold tin plating for my boards,
http://www.rapidonline.com/Tools-Equipment/Tin-plating-crystals-29475
90 grams will make 1 litre of solution, and it takes about 15-30 mins for the board to be plated.  The tin thickness builds up the longer the board is left in the solution. 
I found it makes a difference to the way the solder flows around the connections and it doesn't tarnish or get fingerprints over time like bare copper does. 

[ptricks]

Something else you can use to keep the copper from tarnishing is a permanent marker, but I don't use the black sharpee brand ones. I use some colored markers that are sold cheap in packs of 6 colors. The colors are sort of useful because you can use the different colors to color code parts of the board by their function. The ink burns off when the trace is heated so no problem to remove.

[Stiege]

My laminator finally arrived, can't wait to give it a go!

[Harvs]

If etchant  gets to the point where it can't be re-used you can do a couple things with it. One is plate out the copper, basically need a metal that can be plated with copper and a small voltage source, even 1.5V AA cells will work.  In solutions where there is a lot of copper just placing another metal in the solution will cause the copper to attach itself.

So are you saying that by plating out the copper it makes the enchant useful again? 

Or just that it's useful for when you want to copper plate something?

[ptricks]

So are you saying that by plating out the copper it makes the enchant useful again? 

Or just that it's useful for when you want to copper plate something?

Both.

[GK]

Something else you can use to keep the copper from tarnishing is a permanent marker, but I don't use the black sharpee brand ones. I use some colored markers that are sold cheap in packs of 6 colors. The colors are sort of useful because you can use the different colors to color code parts of the board by their function. The ink burns off when the trace is heated so no problem to remove.

Anything wrong with solder-through conformable coating?

[ptricks]

Anything wrong with solder-through conformable coating?

Depends on what coating and what thickness. I use the markers because they are cheap, readily available , and easy to remove coating if needed.

[GK]

Anything wrong with solder-through conformable coating?

Depends on what coating and what thickness.

I mean the solder-through stuff specifically made for coating PCB's, such as this:

http://au.element14.com/electrolube/cpl200h/lacquer-200ml-aerosol/dp/521462

or this:

http://www.jaycar.com.au/productView.asp?ID=NA1002


After drilling I give the board a good rub down with steel wool (that gets rid of any tarnishing) then lacquer.
Who knows what is in the can from Jaycar though. It might even be watered down with Samxon capacitor electrolyte.

[notsob]

If you are trying to measure current and have high voltages, watch out for leakage.

[ee851]

Is that clear conformal-coating "lacquer" the same kind of "lacquer" used for waterproofing wood ?

As an experiment, I cleaned four copper pennies with vinegar and salt to remove all oxidation, then rinsed them in tap water.
I placed two pennies underneath an inch of distilled water in a plastic container.  I sealed the plastic container with a plastic lid and put the other two pennies atop the plastic lid, exposed to air.

After 117 days,     none of the four pennies is as shiny as it was at the start.     However, the ones immersed in water are shinier than the ones exposed to air--probably half to two-thirds are tarnished as the air-exposed pennies.

So I plan to use Mark's "cold tin plating" on my etched boards.