How do you do your PCBs?

[PekkaNF]

I'm not too reat on PCB making.

And I'm now into this kind of stuff:
https://www.elektormagazine.com/magazine/elektor-201409/27026

PCB # 130297-1
https://www.elektormagazine.fr/magazine/elektor-201406/26534

SMDs and stuf....two sided, way too small tracks...

Pekka

 

 

[CrazyModder]

I have this process for 1- or 2-sided PCBs with SMDs:

1. Make board in Eagle
2. Print on overhead projector transparent sheets with a cheap laser printer
3. Expose PCB with some old (huge) sunlamp
4. Develop with NaOH
5. Etch with FeCl3
6. Drill holes
7. Rub high spots from drilling with scotch brite
8. Tin it by smearing with plumbers tin "stuff" and shooting it with a hot air gun
9. Try hard to ignore the (visual) mess this last step leaves behind with half burned PCBs and swear never to do it again
10. Spray it with some transparent stuff which is supposed to make it even easier to solder, and protect the copper from oxidizing
11. Solder

There you go! Looks like it's a big effort, but all steps are actually quite easy and clean. I regularly find myself doing it even though I only have a few connections to make, I just dig the look of even very small PCBs compared to individual cables on an experimental board.

[PekkaNF]

You use photosensitive boards or do you spray on positive 20 or other UV-sensitive resist?

I have tried to buy some, much of them have gone old before I got them. Is there any other method to check, except to exposure, develop and etch and then try to figure out which step went wrong?

Has anybody tried toner transfer/laminator method?

Pekka

[sparky961]

I've used something called "Press n Peel" quite a lot. It works pretty well if you're careful. Better for boards with some room between traces though. I found it worked much better than direct toner transfer. If you're willing to pay the shipping I'd hapilly send you a few sheets to try out.

[RussellT]

I've done toner transfer with toner transfer paper.  It works OK but I always find the ironing on step fiddly.  It is difficult to keep the film still while you're getting it fixed to the copper and difficult to be sure it's all stuck down properly - especially if the tracks are narrow.

I've tried some of the suggestions on the internet for using glossy paper - they don't work nearly as well as the proper stuff.

I've never tried a double sided board but I think that it would be  difficult to register the second side.  If I had to do a double sided one I might do two boards and put them back to back.

I also try and keep my tracks and pads as fat as possible - easier to drill and solder.

Here's a picture of one I did last month - which gives some idea of how clear the edges are.

Russell

[philf]

Or, if you have a CNC router or mill, try machining them. No messy chemicals, no UV lamp, cheap copper clad board.



Phil.

[jiihoo]

Hi Pekka,

I've used "Thermal transfer paper for PCB" (check ebay.co.uk with this search term, I don't want to link to any individual seller). Works on PCBs of "normal" complexity (i.e. try to avoid traces that are overly thin). All of mine have been fairly simple and the last were done a "few" years ago.

To make a simple double-sided board, iron the transfer on one side first and then drill a couple of locating holes to position the other side correctly. Fold the edges of the 2nd transfer paper to keep it positioned correctly. Try to make 4 extra "locating holes" on your PCB design if you can; if you used some of the normal holes for this then consider plugging them before etching as the edges of the holes you just drilled are not protected and will etch somewhat. Anyway don't make your boards 2-sided if you don't have to and when you do, try to keep the other side simpler to make the locating less critical.

My stack of 20 sheets of thermal transfer paper is from 2014 and none of them have been used  (but I am sure that I'll find a good use for them real soon now...).

You are welcome to a couple of sheets if you want to try them without waiting for long delivery from far away... Just PM me.

The Positiv 20 UV resist is usually good for a long time after the expiration date.


Jari

[PekkaNF]

Thanks.

I have really been thinking of building a small CNC router just to do euro card size PCBs max. Just so hard to get started. I have seen some professional ones and hobby models or DIY types just feel so hopeless.

Direct toner method sounds nice, if it works. Specially if you can print also component outlines, markings and solder mask. I wonder if 3D printer could be used to dispence any of that stuff?

There were some nice stuff on lab when I was studying. Two sided was no problem: taped two repro films together on two sides (easy to index), then slip sensitized and oven dried PCB in between and tape tags on corners to immobilize the PCB and "pouch". But now I have only household stuff.

I'll have to take your offer JH, PM will follow....I have greatest faith on UV resist method, but I really like the direct toner transfer idea.

Pekka

[Joules]

With a small cnc like my old Roland MDX3, you have the option of coating you PCB, then scratch the resist for normal etching.  It means even a small cnc machine can produce boards.  I made this tool to go in the 6mm collet of my little MDX3.

[CrazyModder]

You use photosensitive boards or do you spray on positive 20 or other UV-sensitive resist?

I use pre-made boards from Bungard.

I have tried to buy some, much of them have gone old before I got them. Is there any other method to check, except to exposure, develop and etch and then try to figure out which step went wrong?

The story, as far as I can tell, is that they are forced to print a shelf date on the boards by regulations. In fact, they seem to hold for many years with no problems. Mine did, I'm sure; I have not tracked how old my boards are, but I have certainly used ones of 5 years or older with no noticeable difference.

Has anybody tried toner transfer/laminator method?

I've tried it and found it as hit-and-miss as the other people here.

Really, the NaOH/FeCl3 method is not messy at all. If you are able to pour a liquid from one container into another without making big splashes everywhere, then you'll be fine. Sure, those are chemicals, but only mildly dangerous to humans. You won't get blind from fumes or destroy your lungs or something like that. You can store them indefinitely in plastic containers with no risk of them breaking (check the data sheet for which kind of plastic; I got my containers in a local apothecary when buying 2 liters of aqua dest there, for free ;) ). The dangers appear when you simply pour the used stuff in the toilet (especially the FeCl3 - I have heard that the utilities can track that and you'll get really punished, and the ground water will go to hell ;) ). You can use and re-use the FeCl3 a very long time though, it is very benign. The other danger is of course to clothes, and the FeCl3 will - duh - etch metal, so don't use it in the kitchen in the good stainless steel sink or the wife will put you in pain. All should be pretty obvious. Eye protection and simple gloves should be standard, no questions asked.

There *are* other chemicals that can be used for PCBs which *are* indeed very dangerous indeed. That's why I use NaOH/FeCl3. The FeCl3 step takes a long time (can be like 30-45 minutes) at room temperature, but that's fine with me.

All of those parts are easy to source and cheap (like 1-10€ cheap). The printer is kind of important though; I assume not every printer will give good results on transparents. A slight cloudiness does not hurt, but if there are holes in the print,  you will get holes in your copper. Mine cost < €100. And you can use it for standard printing as well, so I don't count it as investment at all.

[John Rudd]

Guys,
In order to speed up the etching process, I warm my ferric chloride in the microwave oven....depending on the wattage of yours( 'er indoors I should say)...for 10 secs a time...and agitate the board in your etching bath....
It does make a difference.....

John.....pcb etching dept.

[awemawson]

Mine not only warms the Ferric Chloride, but agitates it by pumping air bubbles from below'

Made by Mega, it has a developer tank, etch tank and tin plating tank, with water rinsing slots in between making it all very convenient - has a handy sink built in as well.

Amazing what you can pick up on eBay. 

 This is the second one I've owned. The first one got sold when I moved to reduce volume of the move itself, but this is an improvement as the last one didn't have the sink. 

[CrazyModder]

Yes, if I am in a hurry (and the wife is not around), I simply put my etching container into a hot water bath in the kitchen. Careful not to over-etch, then.

I've made myself a bubbling device as well, but *that* was messy indeed and I just don't need that step to go fast.

But as the OP is hesistant about the method, I'd just like to point out that both of these things are completely optional and just speed things up.

[John Rudd]

I ought to point out that overheating the ferric chloride is not good....
It will turn to ferrous chloride....


John....pcb etching lab services..

[philf]

One method I don't think has already been mentioned is pcb transfers. Similar to Letraset you have pads, tracks etc which you rub down onto bare copper. The transfer is etch resistant. I have some of these in a drawer that I must have had for 40 years so I guess mine won't work now. Electronics magazines often used to include rub-down transfers of a whole pcb for their projects. They were printed by a local guy in Stockport.

I wouldn't like to do a very complex circuit with this method. I used it for doing pcb artworks on drawing film. We had a setup like Andrew's at work so etching was no problem.



Phil.

[sparky961]

Further to my previous reply, I definitely prefer UV presensitized boards but if you mess up its more costly 'cause you can't just remove the resist and try again. The benefit is very fine traces and crisp edges.

Last time I wanted a board I just ordered it online. Can't beat the quality, delivery was quick, no mess or chemicals to deal with. Price is still up there but only if you consider your time free.

[PekkaNF]

Thank you

I'll try Bungard pre sensitized boards and normal laser printer transparencies.

I may try thermal tranfer paper method too, just to have something to compare and that looks like a cheap method.

I do have few UV-tubes, really should build the exposure box. I even bought the acryllic and specially asked the non UV filtering type and got the UV filtering type. Surpricingly I found out too that much of the windlow class has UV filtering...Probably should buy the cheapest picture frames there are to get few correct size glass panels, I'm sure they have no UV protection!

Pekka

[efrench]

I'm in the process of designing my first PCB.  This is the process I'll probably use to create the board:
http://quinndunki.com/blondihacks/?p=835

The board itself will be about 2"x2" with 150 odd holes.

[CrazyModder]

I may try thermal tranfer paper method too, just to have something to compare and that looks like a cheap method.

Sure. In Germany people  traditionally use pages out of the printed catalogue of one of the big electronics shops, for whatever reason that seems to work best (or it is simply because people who do things like this have this kind of catalogue lying around ).

I do have few UV-tubes, really should build the exposure box.

I have one of those old sunlights (I think it is a "Philips HB 171/A" or similar to it) and just prop it up on something when I need it, I didn't feel the need for a proper box yet.

I even bought the acryllic and specially asked the non UV filtering type and got the UV filtering type. Surpricingly I found out too that much of the windlow class has UV filtering...Probably should buy the cheapest picture frames there are to get few correct size glass panels, I'm sure they have no UV protection!

 

[awemawson]

I worked in an electronics lab at Mullards Southampton back in the late 1960's where we had a thing like an Etch-O-Sketch, manually operated you put a clear but coated  film on the bed and shaved the waxy coating off leaving clear track that was then reproduced photographically. The waxy coating was red. When you made a mistake there was a bottle of correcting fluid to cover your mistakes.

Somewhere I too have transfers like Phil's, also a 'tape pen' that lays down tracks from a reel onto your art work.

Then of course there was the 'Dalo Etch Resistant Pen' that you drew your tracks directly onto the copper.

Then 'someone' (me!) found that a thick layer of layout blue was a good etch resist, and was flogging it as such in adverts in the back of Practical Wireless and Wireless World in little bottles. That was in the early 1970's

[PekkaNF]

Sure. In Germany people  traditionally use pages out of the printed catalogue of one of the big electronics shops, for whatever reason that seems to work best (or it is simply because people who do things like this have this kind of catalogue lying around ).

Incidentally I think I have the right catalog to the job, starts with little blue "r"?

Do people soak it long or use other deucedly clever method?

I have one of those old sunlights (I think it is a "Philips HB 171/A" or similar to it) and just prop it up on something when I need it, I didn't feel the need for a proper box yet.

I have bunch of T5 small tubes, 20 cm long or so... Really would like to build a small enclosure a) To keep it safe between uses b) to make it as small as possible. I have way too much trash, treasures, thrashures.

Pekka

[awemawson]

When we were kids just after the war, Sunray lamp treatment was all the rage for pale under nourished children. We had a lethal lamp with a Mercury discharge tube shaped like a horse shoe, little red button on the back to press to start the discharge.

It stayed in a cupboard for years until I needed a uv source for exposing PCB art work. Only took seconds !

Now I have a proper Mega exposure unit with built in timer.

[geoff_s]

Unless it's a really simple, single sided design, I send the gerbers off to somewhere like Seeed and get them made.
Simple designs I route out on the CNC.

[tom osselton]

I have a flip top plate maker for printing presses it has a carbon arc with timer and vacum do you think this would work on the photopolymer paper?

[PK]

Made by Mega, it has a developer tank, etch tank and tin plating tank, with water rinsing slots in between making it all very convenient - has a handy sink built in as well.

We had one of those units for many years. We used Ferric Chloride etchant and ours didn't look much like that picture when we finally sold it. Before that we had one we made from glass. Before that we used one we built from PVC Sheet. Before that we had a little hobby one.....You get the idea..buy decent tanks ..

Our process was:
Inkjet print onto transparency (inkjets have better resolution)
Lay the top and bottom transparencies on piece of paper and align them, hold in place with tape.
Put double sided Kinsten board in and expose both sides in our DIY exposure box.
Etch,
CNC drill.

A word of caution. Making a double sided exposure box is a good idea. Making one with short wavelength tubes is VERY DUMB!  The lighting supplier sold me UV tubes used to sterilise water. Hand on my heart those lights were on for less than 5 seconds and I spent the nigh in emergency with sunburned corneas. I never knew my eyeballs could hurt that much!

The advent of the US$1 per board prototyping services out of china mean that we no longer do in house boards... It's just not worth it...

PK