i only know spray on resist (ready in pressurized can) from "kontaktchemie" but i think this won't be
available where you are. i think the much better idea would be to buy ready made coated clad or do you
have lots of uncoated like mine?
if you are coating yourself remember the following:
clean, clean, clean, before you spray.
try to spray a uniform thickness.
do this in a room with little dust if possible.
shouldn't inhale damps of spray.
after spraying put the pcb in a box (like the ones shoes are sold in)
, you can apply the spray in there also, and put the lid on to prevent dust from settling down.
(the dust would be bad when exposing)
if you have litte time baking and ventilation helps depending on resist kind.
this was told to me by a friend who coats all the boards himself. i never did that.
i may ask him for the brand of resist he uses, but he is located in hungary so this may not help you.
oh, yes, please keep in dark the coating (some minutes in normal indescent light are NO problem, but
prevent direct sunlight and flourescent lights.) especially in drying (Long time), therefore the box is
best suited.
i would really suggest rather using ready coated material, this is covered with protective light dense
foil for storage. only if you have a vast amount of uncoated plain clad i would suggest coating
yourself.
if you have troubles getting it to work simply ask, it is somehow tricky to get it working if you have
no experience with it but after you know how to do it it is a forgiving and simple process.
i don't like it because of expensive pre-coated material and generating the fim, my printer doesn't
make that right..
regards
st
27.04.2003 19:02:00, "Tayyab Jamil Qureshi" <
tjq@...> wrote:
>Hello,
>
>I want to try the photosensitive coating method, I have tried one material available in the local
market but the results were not that good.
>
>Can some one suggest me the names/brands/materials which are photosensitive and can be used for
coating on the plan board to make it photosensitive.?
>
>Regards
>Tayyab
> ----- Original Message -----
> From: Stefan Trethan
> To: Homebrew_PCBs@yahoogroups.com
> Sent: Sunday, April 27, 2003 3:29 AM
> Subject: Re: [Homebrew_PCBs] beginner need help
>
>
> there are three methods which are "beginner level" i think:
>
> first: photosensitive coating
>
> need layout on transparent film or translucent paper, or needs use of pausklar spray (oil).
> then you have to expose it (different cheap light sources possible)
> then developing in NaOH for example (other developer gives less trouble but expensive)
> then rinsing and finally the etch.
> any trace with possible with good artwork.
>
> second: toner iron on
>
> this method uses the plastic ingredients of laser printer / copier toner and somehow transfers it
from
> the printed sheet to the pcb while applying heat and pressure by a hot iron.
> ranges from plain paper, glossy, kitchen baking paper, transparent ohp, speial (expensive) PRESS 'n
> PEEL etc...
> with all papers i think the following process:
> print at darkest setting
> iron on (several tricks here)
> let the paper be dissolved by water or chemical
> ready for etch.
> limitation in trace with is given by widening of trace while melting and other factors, i have no
> experience here, only tried twice and bad results.
>
> third: plot on directly on copper
>
> i'm currently experimenting with that, very fine results, (advantage: only plain copper clad
> (uncoated), not so difficult like iron on).
> you definitely should have a tungsten carbide x grooved metal tip plotter pen, a old pen plotter of
> course (no flatbed needed, works also with hp7475a and clones). further best ink is staedtler
lumocolor
> red ink (better resistant than anything), sold as refill bottle.
> if you have the pen and get a hpgl file from your cad system it should really work fine, as with the
> iron on here you also can plot a professional component outline (colored!). better do it before
> drilling to avoid pen catch in hole and breaking of it.
> limitations in exactness here is pen size (smallest i have is 0,18 mm) and plotter exactness
> (acceptable).
>
> fourth method: printing with inkjet (Straight path) and acrylic floor polish to copper, read here,
no
> experience myself. i believe this acrylic floor polish to be possibly replaced by thinned water
soluble
> laquer but this is only a guess.
>
> if you want any assistance, especially in direct plotting i would provide what i know.
>
> hope that helps..
>
> regards
> stefan
>
> 26.04.2003 22:08:07, "Tayyab Jamil Qureshi" <tjq@...> wrote:
>
> >Hello,
> >
> >I am trying different methods of transfereing my artwork from printed positive to the plain copper
> board, Can any one suggest me the easy and cheap way to make fine tracks.
> >
> >My PCB need to have 10 mil tracks and gaps.
> >
> >Regards
> >Tayyab
> >
> > ----- Original Message -----
> > From: Mike Putnam
> > To: Homebrew_PCBs@yahoogroups.com
> > Sent: Sunday, April 27, 2003 12:10 AM
> > Subject: Re: [Homebrew_PCBs] Re: Oh no, blank fibreglass again!
> >
> >
> > I have to differ with you, Tom. I used Tin Plate (Electrolysis) in my shop
> > for many years and not Gold. Gold plating was too expensive. I etched with
> > Ferric Chloride with no problems ever. Perhaps the trick is in how fast you
> > are able to etch the panel.
> > -Mike
> >
> > ----- Original Message -----
> > From: "twb8899" <twb8899@...>
> > To: <Homebrew_PCBs@yahoogroups.com>
> > Sent: Saturday, April 26, 2003 11:40 AM
> > Subject: [Homebrew_PCBs] Re: Oh no, blank fibreglass again!
> >
> >
> > > Max,
> > >
> > > We always used solder plating as a resist and it worked fine. After
> > > etching either reflow the solder or strip it off and apply one of the
> > > newer "white tin" coatings if you want tin plating. Are you using
> > > immersion tin or really electroplating it? Immersion tin is worthless
> > > as a metallic resist but some electroplated tins will work if they
> > > are plated heavy enough. By switching to solder plating you will
> > > eliminate the problem. The same plating bath can probably be used.
> > >
> > > Ferric chloride will not work unless gold is being used as the etch
> > > resist. Sulfuric/peroxide will work as an etchant for solder plated
> > > boards. After stripping the photoresist dip the panel in a 10%
> > > peroxide dip and then etch. This keeps the black crud from forming on
> > > the solder plated surface for a better reflow finish. After etching
> > > dip the panels in a 10% hydrochloric acid dip for about five minutes
> > > to brighten the solder plating for reflow. Skip the peroxide and
> > > hydrochloric dips if the solder is being stripped after etching. They
> > > are only required for solder reflow quality.
> > >
> > > Bake the boards for at least 30 minutes at 300 degrees F after
> > > etching and before reflowing. This is for outgassing any trapped
> > > moisture and will keep the plated through holes from blowing out when
> > > soldering.
> > >
> > > BTW, are you using the newer activated palladium cataylyst and
> > > skipping the electroless copper stage? Good luck on your new system!
> > >
> > > Tom
> > >
> > >
> > > --- In Homebrew_PCBs@yahoogroups.com, "Max Davies" <max.davies@b...>
> > > wrote:
> > > > Hi everyone.
> > > >
> > > > A newbie to this group, I am (perhaps over-ambitiously) attempting
> > > > to set up a micro through-hole plating line at home. It's a lot
> > > > more involved than I ever thought it would be, but I now have most
> > > > of it working fine. ...Except what should be the easy bit - the
> > > > final stage - the etching!
> > > >
> > > >
> > > > To give a brief description of what I do...
> > > >
> > > > STAGE 1: Starting with plain, copper-clad board, I do the drilling.
> > > > STAGE 2: Apply photopolymer laminate, then expose & develop. (This
> > > > is positive photopolymer, so the copper which will ultimately
> > > become
> > > > tracks is exposed to the air on developing the pattern)
> > > > STAGE 3: Go through a 6-stage process to electroless-plate the
> > > > entire thing (including the holes & edges). The copper cover it
> > > puts
> > > > on is pretty thin, but uniform at 1-2 microns.
> > > > STAGE 4: Electroplate the copper - this gives reasonable thickness
> > > > to the copper applied in stage 3 - I aim for 25 microns.
> > > > STAGE 5: Electroplate with tin to 10 microns. This
> > > > (theoretically!) protects the copper from etchant.
> > > > STAGE 6: Remove remaining resist. Then etch. This should leave
> > > > the tin-plated areas untouched, everything else should be zapped.
> > > >
> > > >
> > > > But alas no! Stage 6 fails, because both tin ∗and∗ copper are
> > > > etched, leaving me with a fine, blank piece of fibreglass! It
> > > > matters not whether I use Ferric Chloride or Sulphuric/Peroxide
> > > > etchant - they both destroy what has been so lovingly created!! So
> > > > I reckon there must be something awry with my tin plating.
> > > >
> > > > It's a total impasse, and nothing I do, from increasing/decreasing
> > > > current to re-formulating the tin plating bath according to
> > > > manufacturer's instructions seems to change things.
> > > >
> > > > Does anyone else use a similar process, or have any clue about what
> > > > might be the problem here?
> > > >
> > > > Max.
> > >
> > >
> > >
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