photoresist - Page 3

masood · 30th April 2012, 12:07 PM

dear sir,
my friend has a chemical that he says glue.he paste the glue on pcb and then he put the negative on it and then he put under sun exposure for 10 minutes after this he dip the pcb in blue colour .the image engrave on pcb.but question is that when the pcb is etch the image is also dissolve .ferric chloride etch both image and non image .How can we make image strong that prevent from ferric chlorde.some people says to dip in naoh i am cofused to know how it is possible and what is the chemical name of that glue.can any body help me .

sek · 30th April 2012, 07:23 PM

Well, the image shows that your friend has the exposure and 'development' process under pretty good control. Sadly it's the wrong chemical to withstand an etchant, just dyeing the exposed areas apparently doesn't change their properties.

With the right lacquer for such a lithographic processes, NaOH is the standard developer. The trick is to find a type of UV sensitive laquer that also resists NaOH in it's unexposed state. Standard products usually don't have these capabilities. The sun makes for a great exposure lamp, though.

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30th April 2012, 07:23 PM	#22
sek diyAudio Member Join Date: May 2003 Location: Berlin	Well, the image shows that your friend has the exposure and 'development' process under pretty good control. Sadly it's the wrong chemical to withstand an etchant, just dyeing the exposed areas apparently doesn't change their properties. With the right lacquer for such a lithographic processes, NaOH is the standard developer. The trick is to find a type of UV sensitive laquer that also resists NaOH in it's unexposed state. Standard products usually don't have these capabilities. The sun makes for a great exposure lamp, though.