Homebrew PCBs

Stefan,

Thank you for such an extensive description of your process. You 
nailed my problems: lousy printer, one iron only and the rest. I 
clean my board with acetone (to remove leftovers and I have always 
plenty of those, don't ask why...), then water with dishwasher soap, 
tehn sandpaper 600, then brillo pad with detergent. Then all is well 
flushed with water.

Your process is interesting, but it takes s much time toand full 
attention. I am for the idea of Ron Peopeil: set it and forget it. 
Which brings me to another idea: chicken grill, just kidding. I agree 
with your supposition that higher temperature is more forgiving than 
lower and that two high pressure is not good for narrow traces.

I ahve one of those $2 grills for hamburgers but their footpriny is 
just too small.

The problem with iron is that I suspect that temperature is not 
evenly distributeed and therefore it must be set higher to compensate 
for the uneveness. However, that higher (than neccessary temperature -
 someone mentioned 130 being needed for fusing..) causes problems in 
areas with widened lines due to pressure. In other words the correct 
pressure and slightly higher temperature in one area becomes correct 
pressure and incorrect temperature in another, due to a temperature 
gradient within a PCB. My next trial will be a Singer iron press that 
I picked up from a  garage sale 2 summers ago for this convenient 
moment of being able to laminate PCBs... Right now I am baking that 
PCB in an oven after I finished pizza and New Year's ham...  Mike




--- In Homebrew_PCBs@yahoogroups.com, Stefan Trethan 
<stefan_trethan@g...> wrote:
> On Wed, 31 Dec 2003 17:37:42 -0000, mikezcnc <marabu@c...> wrote:
> 
> > I am spending lot's of time trying to find the best way of 
heating and 
> > pressing.
> >
> > There appears to be a distinct correlation b/w tempreture and 
pressure 
> > (paper being a given for the ezperiment). I won't mention 
humidity 
> > either.
> 
> You want just enough pressure to make a good bond.
> too much and the tracks widen.
> 
> I always use highest temp setting so far.
> will experiment when i have a other iron (with longer chord and no 
steam 
> holes).
> I think above a certain temperature it works pretty well.
> There must be some upper border but with my iron it seems i don't 
reach it.
> 
> > The other problem I have is that my boards are larger than an 
iron 
> > footprint. Iguess if my idea was to make a small board with heavy 
traces 
> > it would be trivial. With small board and SMD it would be also 
relatively 
> > easy. The problem starts with size. Just yesterday I tried moving 
from 
> > one end to the other end of the large board with fine traces and 
I made 
> > stops with iron every inch and stayed there for a minute and 
half, wool 
> > setting. Some places came up perfect, next to it pads were 
flattened 
> > (pressure issue?) and lsewhere I obviously did not laminate long 
enough. 
> > The good news is that where the ink stuck it did stuck like 
enamel. The 
> > links you are including and are fascinationg how he did it.
> >
> Which toner do you use and which darkness setting?
> For me short ironing works nearly as good as long.
> i use very light pressure, perhaps additional 10N to the weight of 
the iron 
> itself.
> But i mostly make boards smaller then the iron.
> 
> First i put it on the whole surface for about 10 seconds.
> then i start at one side and go over the board slowly, continuously 
with 
> the curved edge.
> the hot aluminium leaves on the paper a print through of the 
underlying 
> toner areas.
> when i can see all areas with the light brown/yellow printthrough i 
know it 
> is ok.
> if not i go over that place with the curved edge again.
> All with very light pressure.
> 
> The whole process takes no longer than 30 seconds.
> I got better results with lighter pressure.
> 
> I assume with that process i coud make larger boards too.
> i would first set the iron in the center for 10 seconds, and then 
the same
> offset all around until the whole board has had the 10 second 
heating.
> 
> (I think that gets the pcb up to temp.)
> 
> then i would go with the curves edge over it like i do with small 
boards.
> (i tilt the iron very slightly to get the pressure mostly on the 
edge.)
> 
> How do you prepare your boards? (cleaning)
> 
> Stefan
> 
> 
> > One more thing: lamiantors require 12 to 15 passes... I want a 
better 
> > laminator. Just went thru an excercise with the heat press-worse 
than 
> > iron. Is there anybody knowledgeable to suggest how to control 
heat and 
> > pressure on large size PCBs. Oh, I even had my boards preheated. 
I use 
> > dmax pressure but probably not evenly.
> >
> > Mike
> >