lately all my pcb's turn out like this

[gutsofgold]

Here's my method:
-Print layout on regular paper, then tape PNP over it and send it through again, printing to the dull side of the PNP.
-Cut board and sand it with Scotch Brite pad.
-Clean board using paper towel and Denatured Alcohol
-Place PNP on the board shiny side up, Iron one corner until it sticks.
-Push down with moderate pressure on the middle of the PNP and then on each side/corner, do this for about three-four minutes
-Immediately take board to sink and run under cool water for about a minute.
-Peel.

I get this...
http://img.photobucket.com/albums/v102/timie/IMG_1157.jpg

Now I've done plenty of good boards using photopaper so I have to assume it's the PNP... Does PNP require a lot more heat/pressure? Could my Iron be the culprit since the bottom of it is scratched up and dirty?

[Papa_lazerous]

-Print layout on regular paper, then tape PNP over it and send it through again, printing to the dull side of the PNP.

YEP thats fine!


-Cut board and sand it with Scotch Brite pad.

It should be smooth as a babies bum when bought I just clean it with some alcohol, but if its tarnished a very light going over to remove an oxidisation will suffice it looks quite abused in your picture!

-Clean board using paper towel and Denatured Alcohol

Yep good plan

-Place PNP on the board shiny side up, Iron one corner until it sticks.

I tend to lay the iron flat over it all at once just to it gets tacked to the board, I also have the iron set on the same temp I use for my normal ironing

-Push down with moderate pressure on the middle of the PNP and then on each side/corner, do this for about three-four minutes

sounds good

-Immediately take board to sink and run under cool water for about a minute.

NO NO NO, why would you imerse it in water??  give it about 30 seconds to cool and gently peel from one corner, if it hasnt stuck then you can always re iron.  I find when ironing on PNP you can see the PNP seperating where the tracks are put the tip of the iron on a track and move it along it applying a ltitle pressure you should visibly see that its different to an area with no heat on it


-Peel.

Yup that bits cool too

[dschwartz]

i use normal paper for toner tranfer..the secret for me is the ironing..a good hot iron and patience..sweeping with the border of the iron helps too.

then dissolve the paper with water and get good results..
i used PNP for a while, but didn´t like it cause once you screwed up..all the work is gone..and PNP is not cheap ir readily available here in chile...

[tiges_ tendres]

The first tutorial I saw talked about running the board under water to cool it off.  That just seems wrong to me.  Lets say you start to peel away your pnp and it hasnt adhered well.  Well, now you cant really iron over it again because its all wet and the water has loosened up the pnp.

A better way to cool off your board is by putting it on something cold.  I keep a large metal enclosure around and i place the pnp face down on it.  It sort of acts like a heat sink.  After 20 seconds or so, I move it to a colder part of the enclosure and continue to move the board until it is only luke warm.

You could also use a glass of ice water on top of the board too.  Just make sure your glass is plenty thick, and tempered too.

Preparation and Patience are the two most important tools you have when making PCB's (which is why I moved over to Vero  )

[cpnyc23]

I recommend sitting the iron on top of the PnP & bare circuit board for about 30 seconds - this warms up the copper evenly across the whole surface.  Then lay the PnP down (carefully).  After that I switch between slowly ironing back and forth across the board and just leaving the iron to sit on the board for a few seconds at a time.

From the looks of it, I would guess that you aren't using a hot enough iron.

-chris

[BINGEWOOD]

Check your print settings to make sure you aren't using a toner saving setting if the toner cartridge is on the newer side.  I have only had the sort of result you are showing from a toner cartridge that was low and needed to be replaced.  It would still give a decent looking output but would not transfer correctly.  Changing the cartridge worked for me.

[John Lyons]

I'd say too much heat and possibly too much pressure.
Maybe too much time as well. I don't spend that long even with photo paper.
Try few scraps as test runs. Just cut up a few small scraps and try with different heat and times.
Isn't there a set of instructions for PNP from the maker?

john

[neil411]

I have two things that I do to make sure the toner stays put:

I run the iron pretty hot, up in the "cotton" range. and I leave the iron on the PCB for at least two full minutes, moving it all the time.

I leave it alone for at least 15 minutes and let it cool off naturally to room temperature. I don't blow on it, run it under water or anything.

My early attempts looked like yours do until I did those two things.

[aloupos]

I've spent the last 2 years perfecting the technique, although I still get inconsistent results from time to time. Usually just a 3-5mm piece of trace that doesn't come through.  The problem is usually a combination of things: 

1.  Prep.  I use cleanser, water and scotchbright (green pads).  To make sure you clean the surface well, scrub horizontally from top to bottom, then vertically (left to right or whatever), then for good measure, diagonally.  Rinse really really well.  Any residue will cause issues with toner adheasion.  So will fingerprints. 

2.  Depending on how you've cut the board, there might be burrs on the edges.  Burrs don't let the iron sit perfectly flat on the board.  I file the edges of the board at a 45 degree angle. 

3.  Heat.  Not enough and you won't get traces, too much and you don't get clean edges or the hole in the pads fill with ink.  Unfortunately, every iron is different and produces different heat on different settings.  I've always wanted to get a laser temperature sensor to measure ...

4.  Time is related to heat, and too much has the same effect.  When trying to find a working heat setting, aim to iron for around 3 minutes for a small board (< 3" square).

5.  Motion.  I've tried everything, from clamping the iron tight to using a bar as a fulcrum to light or heavy ironing motion.  I settled on 30 seconds with the iron resting on the board, iron a bit, wait 30 more, iron a bit, etc. 

6.  Cool and peel.  I drench with cold water, use a paper towel to dry the top, then carefully peal the pnp off.  Leave a little extra pnp to use as a handle to peel off.  As you're pealing, see if you're missing traces -- if you are, go back and iron for 1 min, try again, repeat. 

If you're pads close, you're using too much heat or ironing for too long.  re-clean the board and try again at a lower heat setting. 


That said, John Lyons seems to get almost perfect results .. maybe he'll share his process.

Anthony

[John Lyons]

I do some of the same things Anthony.
I use photo paper and get far from perfect results but I have some cheats here and there.

Here's a rundown of what I do.
http://www.mrdwab.com/john/How-to-make-PCBs.html

(I now use only steel wool to scrub the board though.)

john

[soggybag]

I put my boards under cold water after ironing. I have read this in tutorials on the subject. Seems to work.

I would guess that the toner is not sticking to the surface for some reason. The surface is not clean. The toner is weak on the PNP. Or, and this is probably the most likely reason, the iron is not hot enough.