i have the spray "pausklar 21" here.
this is a light oil which smells like the oil in orange peelings.
it should make the paper transparent (to uv).
i used it quite a while, because my laser is poor on transparency.
but the results are not that good.
the problem is because it is a fluid it builds small "lakes" between the paper/ pcb and paper/glass.
because of reflection etc. this "lakes" have other light transmitting value then the areas where a small
gap of air is in between.
this shows up very strong when developing.
also if you expose with a hot lamp the pcb gets hot too and there appear bubbles of air between the
layers even if you have put that much spray on it to get the whole area filled with oil.
i can not recommend this method, i think it is not good for (semi-)prefessional use.
maybe it gets better if you let the paper dry some minutes to get excess oil evaporating.
the oil also dissolves toner.
if you expose it with a hot lamp (the pcb only gets warm so that you still can touch) and when the time
is elapsed you peel of the paper the traces stick partially to the pcb.
(if you let the oil completely dry up the paper looks like before without oil applicated)
as a conclusion i can say it is possible to get it working.
i don't wat to make any confirmations about the possible trace with. i remember doing 0,3 or even 0,2
millimeter with it. (space between wider but won't be the limit).
but you really have to know how your developer works and you have to cope with several disadvantages.
if one wants to use photopositive process i can only suggest not to make it that weak and messy and less
powerful with trying to use this oil.
good transparencys are a better idea.
(if no way: i read of process using transparent (photo)film and printing on paper. then exposing
transparent film with artwork on paper lying on it for only some seconds (without oil but i think
water). this short time is because of sensitivity of film.
disadvantages obvios: expensive and darkroom work.)
but there is one REALLY GOOD USE FOR THE OIL:
it is the finest stuff for removing the rests of the covering foil on the pcb.
i had some pretty old stuff where the black cover didn't come of good at the edges.
the oil was a wonderful solvent for this sticky stuff but leaves alone the photopositive layer.
maybe it is a good solvent for other sticker residues too... never tried...
regards
stefan
18.05.2003 18:47:18, "Leon Heller" <leon_heller@...> wrote:
>
>
>>From: Chris Graham <Chrisgr@...>
>>Reply-To: Homebrew_PCBs@yahoogroups.com
>>To: Homebrew_PCBs@yahoogroups.com
>>Subject: Re: [Homebrew_PCBs] How I make my PCBs
>>Date: Sun, 18 May 2003 08:15:40 -0700
>>
>>Hans Wedemeyer wrote:
>>
>> > I make double side board all the time. I used to do it the way you
>> > mentioned, and even wrote a program for my CNC mill to compensate for
>> > alignment problems.
>> > I found a better way by printing on transparencies and then aligning
>> > them visually, then stapling them together. Then slide the board in
>> > between the transparencies and sandwich the whole lot between two plates
>> > of glass, and place the sandwich between two lamps
>>
>>I make boards almost exactly the same way, also using Eagle. I print with
>>a
>>Brother 5040 laser printer at 1200 dpi on overhead transparency slides.
>>I've made double sided boards down to 10 mil traces.
>>
>>I decided to go with Eagle (even though I don't really like its user
>>interface because of) its stability, the extensive parts libraries, and
>>the
>>very active support and user forums. Even if I don't find the exact part I
>>want in an Eagle library I can usually find something close that I can
>>start
>>with - much easier than starting from scratch on a new part. And if I have
>>a
>>question or problem I've always been able to get a quick answer on one of
>>the forums.
>>
>>Regarding printing transparencies, one minor irritation I'd like to
>>overcome
>>is that dark areas on the slides aren't as opaque as I'd like, and I've
>>needed to double up the top and bottom transparencies, for a stack of four,
>>which is a little tricky to align and keep aligned.
>>
>>What media do other people print slides on?
>>
>>Also, I read somewhere of someone who printed "transparencies" on normal
>>paper and then made them more transparent by spraying them with some
>>solution (maybe spray silicone?). These resulted in very opaque dark
>>areas.
>>They needed somewhat longer than normal exposures, but produced excellent
>>boards. I now can't find where I read this, and would love to know the
>>details of the process. Are any of you familiar with this?
>
>
>ESR (http://www.esr.co.uk) sells a spray to make paper transparent. I
>haven't tried it. I've heard of people using cooking oil, and tried it once;
>it works, but is a bit messy.
>
>
>Leon
>--
>Leon Heller, G1HSM Tel: +44 1424 423947
>Email:leon_heller@...
>My web page: http://www.geocities.com/leon_heller
>
>_________________________________________________________________
>It's fast, it's easy and it's free. Get MSN Messenger today!
>http://www.msn.co.uk/messenger
>
>
>
>Be sure to visit the group home and check for new Bookmarks and files:
>http://groups.yahoo.com/group/Homebrew_PCBs
>
>To unsubscribe from this group, send an email to:
>Homebrew_PCBs-unsubscribe@yahoogroups.com
>
>
>
>Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
>