Archive of the former Yahoo!Groups mailing list: Homebrew PCBs

On Sat, 11 Oct 2008 17:28:36 +1100, you wrote:

The original Kodak KPR liquid resist was short wave UV sensitive. You
used bare mercury arc fluorescent bulbs with a major amount of
shielding to you couldn't see them. That's the same thing that turns
out to be a germicidal lamp. Sufficient exposure of your eyes to this
stuff causes permanent blindness.

The positive acting resists that are currently available seem to be
exposed with either blue/white (8000 degree K) light a la MG chemicals
instructions or longwave UV which seems to work well on GC chemicals
boards.

Exposure through a printed transparency (black laser) is touchy, since
the laser print is not completely opaque. Can be done, though, if
you're being careful.

Have since switched to DS work with toner transfer.

Harvey

>Hi ,The picture of the lamp in the instructions looks like a sunlamp (UV)
>type of lamp by the shape. There is no description as to what the film is
>sensitive to, every resist I have seen used over the last 30 years has been
>UV sensitive.
>Don VK3YV
>----- Original Message -----
>From: "pixelcanvas" <pixelcanvas@...>
>To: <Homebrew_PCBs@yahoogroups.com>
>Sent: Saturday, October 11, 2008 12:50 PM
>Subject: [Homebrew_PCBs] Re: Dry film woes, maybe the developer is at fault?
>
>
>> --- In Homebrew_PCBs@yahoogroups.com, "warrenbrayshaw"
>> <warrenbrayshaw@...> wrote:
>>>
>>> "pixelcanvas" wrote:
>>> >
>>>
>>> > The stuff I'm testing is this:
>>> > http://www.es.co.th/Detail_eng.asp?Prod=WARA%2DDRYFILM
>>> >
>>> > I get it locally (I live in Bangkok), and unfortunately the
>>> > instructions are in Thai... my girlfriend helped me out with it but I
>>> > still think there may be something wrong with them...
>>> >
>>>
>>> As this appears to be Wara product try the manufacturers web site to
>>> confirm your translation was correct.
>>>
>>> http://www.warapcb.com/dryfilm.php
>>>
>>> All the best
>>
>> Yes, the translation is correct, but I have serious dubts about it's
>> usefulness. For example it does say to use a 100W light bulb for 15
>> minutes to expose the film, and I know for a fact that is way too
>> little time. So I think I should take those instructions with a pretty
>> large grain of salt...
>>
>> Harvey, I think what you are saying about the bottom of the film not
>> being exposed may be correct.
>> I'm going to try to get an UV light, and expose a test board at
>> different times, I'll place a piece of cardboard over it and move it
>> to the side every 15 minutes or so to expose more of the board. Then
>> I'll see what exposure time works best.
>>
>> Thanks lot for the suggestions so far.
>>> Warren
>>>
>>
>>
>>
>> ------------------------------------
>>
>> Be sure to visit the group home and check for new Links, Files, and
>> Photos:
>> http://groups.yahoo.com/group/Homebrew_PCBsYahoo! Groups Links
>>
>>
>>
>
>
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