Homebrew PCBs

The resist is interesting indeed.  It develops in 5 seconds with a 1000w
light.  It does use the same 1% solution of sodium carbonate for developing
as other resist brands. 

 

They instruct exposing and then developing as normal.  They say then to
expose it again to harden it further.  I never thought of the extra
hardening step.  I will use it.

 

The instructions say to use a spray bottle or lawn pump sprayer to apply the
developer saying it will strip unexposed resist easier without abrading
exposed resist.  If a spray bottle can be used for applying developer, could
it work etching?  Has anyone ever tried it?

 

Jeff

 

  _____  

From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
On Behalf Of smilingcat90254
Sent: Tuesday, January 08, 2013 8:13 PM
To: Homebrew_PCBs@yahoogroups.com
Subject: [Homebrew_PCBs] photo resist. Slightly different material.

 

  

Some of you have complained that the resist lifts off or gets damaged during
handling. laying of the transparent image, static electricity causing the
resist to lift off with the image, vacuum bagging causing more surface
scratch and so on. 

and the use of chemicals.

I just recently ordered a material called puretch from only US distributor.
claims that the film is good down to 1 mil resolution provided your image is
that good.

links to the US distributor: www.capefearpress.com/puretch.html
youtube videos on the product: www.youtube.com/watch?v=xkGt9nFER1s

another link: http://www.polymetaal.nl/siteUK/shopukwork/en-gb/dept_183.html

Developer used is sodium carbonate (do not get it confused with sodium
bicarbonate which is baking soda)

capefear press has some good information on how to expose without creating
shadows and the lamp recommended. Good solid information. Application at
capefearpress is not electronics but rather arcane art form. Far more
technical than most of us here or using toner transfer method.

Some advantages: photoresist is protected from handling by a thin plastic
layer. It is removed when you are ready to develop so that you can't scratch
or lift off during handling and exposing.

For photoimaging, they also sell stoufer exposure gauge to help you get the
right exposure.

------------
For now I think I have Pulsar toner transfer system working well enough.
Don't need to use lot of pressure. Too much pressure causes the toner to
"bleed" on the edges. temperature to melt toner is around 100C anything more
and the toner becomes too thin and the image "bleeds"/run.

I may still switch over to puretch. Don't need to keep printing images for
multiple board. higher resolution for use with TQFP with 0.5mm pitch. Pulsar
is near the limit for 0.5mm pitch.





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