Oops!
        sorry- I suppose the correct term would be organometallic, as the
dye structure is a copper complex (inorganic/metal) with phthalocyanine
groups (organic) surrounding it.
To answer your further question, I am not I pigment expert but there are
some inorganic chrome-based pigments that are pretty stable. I don't know if
anyone uses these type of pigments in soldermasks, though.

-----Original Message-----
From: Ken Fong [mailto:[log in to unmask]]
Sent: 17 February 2000 04:18
To: [log in to unmask]
Subject: Re: [TN] Why are soldermasks green?


     David,
     In your 2nd explanation, you mentioned the word "organic", could it be
     inorganic? If yes, are there any inorganic heat stable colour?

     Regards,
     KenF, Feb 17,00


______________________________ Reply Separator
_________________________________
Subject: Re: [TN] Why are soldermasks green?
Author:  "TechNet E-Mail Forum." <[log in to unmask]>           "Albin  David"
<[log in to unmask]> at Internet
Date:    2/16/00 1:54 PM


I can offer two other alternative explanations:
(1)     When PCB's were hand assembled, a great many of the operators found
the green colour 'more restful' on the eyes than other colours used.

(2)     A more likely explanation is that the green colour is usually from a
copper phthalocyanine pigment, which at the time of the first boards, was
the only heat-stable organic colour.

David Albin
Project Leader
Coates Circuit Products

-----Original Message-----
From: Arturo Aguayo [mailto:[log in to unmask]]
Sent: 16 February 2000 08:14
To: [log in to unmask]
Subject: [TN] Why are soldermasks green?


I was recently asked by a college student working on a research project,
"why are printed circuit boards green?". The short answer to that is that
they are green because of the soldermask color. Which led to the next
question "is there a reason why soldermasks are green?" To this question I
had no answer and therefore turn to this forum to see if anybody might know
the reason (I wouldn't want a student to not graduate because of me).

regards
Art Aguayo

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