TreadBot

[mister_e]

transparencies film work great with inkjet printer. That's what i use here. Set your printer to the best resolution mode... yeah slower but better.

I tried laser printer in the past. i gave up, sometimes the toner don't do a nice and perfect job on 10-12mils traces.

Home made Thru-hole plating would be nice... but not a trivial thing. Sure there's some rivet kit available here and there... but it's a little bit expensive for what it worth. Better to outsource your PCB to some cheap PCB fabs.

Good luck!

[skimask]

transparencies film work great with inkjet printer. That's what i use here. Set your printer to the best resolution mode... yeah slower but better. I tried laser printer in the past. i gave up, sometimes the toner don't do a nice and perfect job on 10-12mils traces. Home made Thru-hole plating would be nice... but not a trivial thing. Sure there's some rivet kit available here and there... but it's a little bit expensive for what it worth. Better to outsource your PCB to some cheap PCB fabs. Good luck!

Inkjet? Really? I didn't think that worked at all! I tried the 'Press-n-Peel' method awhile back, used the good laser printer at OfficeMax, was really careful and all that. But it seemed like my problem was with the toner.
Does the ink actually dry on the transparency or do you have to be fairly careful with it (i.e. don't bend it, etc.)? How small are you able to get reliably on the traces and circles and the like?

[mister_e]

I've never had enough guts and patience to try the press and peel method. Yeah i like dealing with chemicals and black-rooms

Depending of your printer, you won't need to care about film handling. I'm a Canon printer fan. I use a IP4200. I print the film, wait 20-30 second (just for safety sake) then do the exposure job.

The ink stick on those film really well, you can bend them as you wish. no real problem. Just make sure you select the right film model for the right printer brand and you're in business.

I'd compare few film brands to see if there's any difference between them. Not really. I use those from staples.

PCBs brand make a difference. Here we can have those from C.I.F (circuit imprimé francais) or MGChemicals. By far, i prefer MGChemicals. Hassle free, work all the time.

[dragons_fire]

i tried a transparency on my injet on the last board i did, it worked amazingly well, nice and dark, with nice edges and all... my printer doesnt have rollers after the printing head, so i dont have to worry about it smudging, i just have to let it dry for 10 minutes after..
unfortunately, with the last board, my overhead got scratched and the board came out bad...

i think what i may try, is getting a laser printer, adn try ironing the toner onto regular (not-presensitized) boards. that way, i can use cheaper boards, and skip some of the chemicals..

[mister_e]

this method may have it's advantage for sure. My biggest concern, and also why it doesn't turn me on, is the precision of your layout alignment when doing a double sided PCB. With transparencies film it's just soooo simple to do.

You place your 2 films on a white sheet (or lightened table if you have any) align them perfectly, stick them together with tape on 3 edge (create a kind of pouch) and VOILA!

Place your film on your exposure gizmo, place your PCB the way you want without having to care about alignment, start neons, few minutes later it's done... on both side!

But yeah... you have to deal with exposure time, chemicals etc... but it's working really well. I did many successful prototype PCB using fine pitch SMD components, i can't confirm if the toner method would work as this well. But as long as it's working for you... life is good

If you scratch your film, or you use a fine tip ink pencil.. or simply print it again. Make sure you inspect them carefully first.

If you mess the toner transfer, what happen? is this easy to remove? What is the aprox cost of a toner-transfer sheet?

Films can be reuse again and again.

[skimask]

Place your film on your exposure gizmo, place your PCB the way you want without having to care about alignment, start neons, few minutes later it's done... on both side!

But yeah... you have to deal with exposure time, chemicals etc... but it's working really well. I did many successful prototype PCB using fine pitch SMD components, i can't confirm if the toner method would work as this well. But as long as it's working for you... life is good

If you mess the toner transfer, what happen? is this easy to remove? What is the aprox cost of a toner-transfer sheet?

Films can be reuse again and again.

I didn't realize you were using the pre-sensitized boards. I tried that too... used a couple of 15w flourescent bulbs for exposure (not even close to the right equipment to be sure), couldn't really get the hang of it. I suppose it was because of those bulbs I used.
Toner Transfer Sheets $ - they weren't cheap, cheaper than presensitized boards, but a guy still has to buy the blank copper. If you screw up the toner, sure you can take it off with a steel wool pad, but then you have to start over again, transfer it somehow, blah blah blah.
I'd really love to get my hands on one of those Protomat S62's for the house...only $25K with the options...pocket change! NOT!

[mister_e]

Yeah it's one of those machine some may want to have hanging on their bench

Maybe your tube haven't the right specs, were to far of your PCB, or your exposure time was not appropriate. You have to use special wave lenght tube (UV). regular Black-light tube (or lamp)have nothing to do with that. I usually pre-heat my tube before for 1-2 minutes.... once again for safety sake.

Once you have did few experiments, you know how much time your exposure time will be... it's almost the same everytime.

At least you will scrap 1 big PCB. if you're using 2-3 tube, this MUST take less than 2.5 minutes.

1. Start the exposure lamps and hide major part of your whole PCB with an opaque material
2. wait at least 1.5 minutes
3. move the opaque material to reduce the 'hidden from UV' PCB area every 5-10 seconds
4. develop the whole PCB and look where your PCB look the best.

At the bottom of this link, it's almost what i said... but in english
http://www.turbokeu.com/myprojects/pcb.htm
Enjoy and have fun with the pcb etching and... drilling job

EDIT: i heard some use now ultraviolet LEDs...

[dragons_fire]

the board is done now, and some of the stuff is mounted to it. im using the pic18lf6585, which is the low voltage one (but should work from 2 - 5.5V) and i have a 5V 5A regulator. when i connect the battery without the chip in its socket, everything works fine, as soon as i stick the chip in, the PIC and the Regulator heat up... i havent let the smoke out "yet" but they did heat up lots, and might not be any good anymore... i checked to see if i had Vss or Vdd backwards (so when i put the chip in, it would short out) but everything looks good.





if anyone has any ideas of why its doing that, please let me know.. heres a pic of the bottom of the board on my first attempt with the toner transfer method. the top didnt turn out as good, but there is only 3 traces on the top, and they werent affected.


my last question for everyone is: For PICs that have multiple Vss and Vdd's, do they all need to be connected (they are on this board), or are they connected internally?

[mister_e]

All VSS and VDD have to be connected.

From what i see on your picture, there's few potential traces short-circuit. Assuming there's no routing mistake and the original design worked, You should do a visual inspection first then use you Multimeter.
<img SRC="http://www.picbasic.co.uk/forum/attachment.php?attachmentid=1538&stc=1&d=117673623 8">

Seems to be caused by a lack of etching time or toner transfer... i can't tell.

The overall layout and routing looks good, the final results... so so. I try to avoid 90 degree routing, the etching process work better. It have also other benefits in high frequency.

I also try to avoid unconnected 'ground plane dedicated' copper islands.

Check if there's any polarised capacitor connected backward.

[skimask]

my last question for everyone is: For PICs that have multiple Vss and Vdd's, do they all need to be connected (they are on this board), or are they connected internally?

All Vss's must be connected together outside of the chip, same with Vdd.

And nice job on the PCB...really. The only things I was going to mention...mister_e already covered them...

As far as overheating, with the PIC out of the socket and power disconnected, if you put a meter between any Vss and Vdd, what do you get for a resistance reading? How about a Vf reading (normally seen as a continuity test on a meter when really it measures a diode's forward voltage)... Now try it with the PIC in the socket and power still disconnected?
Then hook up the meter to Vdd & Vss, turn it on volts, put the PIC in the socket, and plug in power just long enough to read the meter. Did the meter come up to system voltage? In other words...dead short somewhere on the board?