Common fiberglass epoxy boards (help me here Ray H.) have been translucent green
since 196~ (when they were also blue and tan and of course phenolic boards were
orange-brown). I have tried yellow silkscreen and it's very hard on the eyes -
we did not like it. Also, when it is screened very thin (or narrow) it is
translucent almost transparent whereas white is very high contrast relative to
green. Also, there is yellow and there is yellow and everyone would argue over
the shade. With white there is no argument as that pigment is WHITE. Yellow,
by the way, has to have white in it or you can't see it.
Bob Landman
H&L
----- Original Message -----
From: Abd ul-Rahman Lomax <[log in to unmask]>
To: <[log in to unmask]>
Sent: June 15, 1999 3:20 PM
Subject: Re: [DC] Origin of green??
> At 05:06 PM 6/15/99 +0800, Lum Wee Mei wrote:
> >I quite like the reason Bob gave. Solder mask is green so as to blend with
> the light greenish colour of the
> >printed circuit board before masked. The light greenish colour of the
> printed circuit board if my memory
> >does not failed me comes from the combination of the resin and epoxy being
> used. The percentage between
> >them and also the woven glass cloth give a slightly different colour.
>
> I'd say that this begs the question. If solder mask is green to blend with
> the color of the plastic laminate, first of all, why should it blend? And,
> secondly, why should the *laminate* be green? Epoxy resin itself is not
> green; rather it is clear.
>
> I've seen specifications on many drawings requiring that the solder mask be
> green, but I've never seen a reason stated anywhere.
>
> My suspicion is that, first of all, someone, somewhere, decided that a
> particular grade of epoxy/fiberglass laminate should be colored green, to
> distinguish it from other grades. I couldn't find my old copy of
> MIL-P-13949, and it is distressing to be reminded once again that, still,
> all these standards and their descendants are available only for sale at a
> fairly stiff price, and not for free download, especially considering that
> the MIL standards, at least, were written with public money.
>
> Now, another related question: why is white more or less the standard color
> for component legend ink when it's been considered for years that yellow is
> a better color to use, by those who specialize in such details (like Preben
> Lund), due to the increased contrast.
>
> I'd think that an opaque, or semi-opaque, solder mask might be easier to
> inspect.
>
> [log in to unmask]
> Abdulrahman Lomax
> P.O. Box 690
> El Verano, CA 95433
>
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