X-Authentication-Warning:	delorie.com: mail set sender to geda-user-bounces using -f
X-Recipient:	geda-user AT delorie DOT com
X-Spam-Checker-Version:	SpamAssassin 3.3.1 (2010-03-16) on
	ham01.websitewelcome.com
X-Spam-Flag2999:	NO
X-Spam-Level2999:
X-Spam-Status2999:	"No, score=-0.0 required=5.0 tests=BAYES_40
	autolearn=unavailable version=3.3.1
DomainKey-Signature:	a=rsa-sha1; q=dns; c=nofws; s=default; d=gibibit.com;
	h=Received:Date:From:To:Subject:Message-ID:In-Reply-To:References:X-Mailer:Mime-Version:Content-Type:Content-Transfer-Encoding:X-BWhitelist:X-Source:X-Source-Args:X-Source-Dir:X-Source-Sender:X-Source-Auth:X-Email-Count:X-Source-Cap;
	b=BlxxdYaVuwq0Ph41xq2q8QK3fxwJv4sXN2VqqiaAs7DhMo4WVFuQtKLlmeu4B2fSZpkmX+Zg9mveGdTW/2qxgiPUVsveaMKULSt9W5o45CnwpR+7w82C81OYHIHHJRtR;
Date:	Wed, 26 Oct 2011 11:08:04 -0700
From:	Colin D Bennett <colin AT gibibit DOT com>
To:	geda-user AT delorie DOT com
Subject:	Re: [geda-user] through hole electrolytic capacitor convention
Message-ID:	<20111026110804.242ff42c@svelte>
In-Reply-To:	<20111026121027.4a20fc1f@rainbird>
References:	<4EA7E80B DOT 902 AT optonline DOT net>
	<20111026121027 DOT 4a20fc1f AT rainbird>
X-Mailer:	Claws Mail 3.7.9 (GTK+ 2.24.6; x86_64-pc-linux-gnu)
Mime-Version:	1.0
X-AntiAbuse:	This header was added to track abuse, please include it with any abuse report
X-AntiAbuse:	Primary Hostname - gator297.hostgator.com
X-AntiAbuse:	Original Domain - delorie.com
X-AntiAbuse:	Originator/Caller UID/GID - [47 12] / [47 12]
X-AntiAbuse:	Sender Address Domain - gibibit.com
X-BWhitelist:	no
X-Source:
X-Source-Args:
X-Source-Dir:
X-Source-Sender:	spk.venturedesignservices.com (svelte) [65.61.115.34]:63912
X-Source-Auth:	colin AT gibibit DOT com
X-Email-Count:	1
X-Source-Cap:	c2t5bGVuO3NreWxlbjtnYXRvcjI5Ny5ob3N0Z2F0b3IuY29t
Reply-To:	geda-user AT delorie DOT com
Errors-To:	nobody AT delorie DOT com
X-Mailing-List:	geda-user AT delorie DOT com
X-Unsubscribes-To:	listserv AT delorie DOT com

On Wed, 26 Oct 2011 12:10:27 -0400
Vanessa Ezekowitz <vanessaezekowitz AT gmail DOT com> wrote:

> On Wed, 26 Oct 2011 06:59:23 -0400
> gene glick <geneglick AT optonline DOT net> wrote:
> 
> > Pin 1 is square, and represents positive pin of cap.
> > 
> > On silkscreen, is it customary to add a marking to indicate +
> > or - side of cap?  The electrolytics have that big stripe,
> > which is the minus side, so I thought maybe the silkscreen
> > should have some sort of marking.
> > 
> > Any conventional wisdom on this?
> 
> I usually mark the positive side (with a "+" of course), and this
> is pretty much how I've always seen it done, in production boards
> whenever I tear something apart, short of using the shape of the
> component or a beveled corner as the marking in some
> surface-mount stuff.

I too like to use a "+" since it clearly communicates what that
pin's purpose is.  However, to make assembly easier and reduce
chance for error, it is helpful to have component markings
specifically match the silk markings on the PCB if possible.  For
instance, it is often unclear which terminal of and SMT LED is
the positive terminal, so it would be nice if the PCB somehow
made it clear which way to place the LED without forcing the
assembler to look at the data sheet.  When I know exactly what the
component model is, and its *specific* markings, I sometimes make
my special footprint silkscreen match these specific markings.

E.g., some SMT LEDs have a beveled edge on the positive terminal.
For that footprint I will make sure I put a corresponding bevel in
the silk so at assembly time it is clear which way to put the
component.  For instance, my Optek OVS5MWWBCR4 [1] footprint has a
bevel corresponding to the bevel on one corner of the actual device.
But, this bevel is obscured when the part is installed, so I also
add a "+" outside the device footprint area so that visual
verification of correct orientation is possible after installation.

Regards,
Colin

References
----------

[1] Optek OVS5MWWBCR4 on Mouser, with photograph.
<http://www.mouser.com/ProductDetail/Optek/OVS5MWWBCR4/?qs=lKzSGHz6MSDvIrs9wCqmHw%3d%3d>

- Raw text -