X-Authentication-Warning: delorie.com: mail set sender to geda-user-bounces using -f X-Recipient: geda-user AT delorie DOT com X-Original-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=dcarr-org.20150623.gappssmtp.com; s=20150623; h=mime-version:in-reply-to:references:from:date:message-id:subject:to; bh=cBk8ZJJd3gqURmnzukb0eMiQ8lrwk+nzLjt1LWw/ONM=; b=ojzdLPVKc8NlkDYRuGgGEKlvQcepr/AcaaILVxHMtK7hfEKYs4jEd7rGhaAuYJnZk0 vmvwP0Q7INk+mOGdJLMGgqXNMulDCbgl8WyFHKVpjkWHQAROWsrCn8J9Rnb1v+PjvgpL 2cGj7YqhWsGx3IfNNfmje75L0vhnfx7PlvmVWG20MUl8thwg2cx6DDGIkYn9zo8vEjpl xGdvPlKWPhB2HMk0GQhVZHUqfJO/5ZWa5ZGe97a1iYcVOAXWUu6RiCXZ4qa5i0RwQlqn PUnn2jLMIrpvvKz+JLX7i3zA5IXewqJ3s1LSIoIOSTZWnL4kmMFJasOsunrXVLEM4X8Q RBIQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to; bh=cBk8ZJJd3gqURmnzukb0eMiQ8lrwk+nzLjt1LWw/ONM=; b=UcMOimacEJXK/AvShcvoLJUbCft/G0fNuBGDqpUkkgrRyYE3E/ZFXhBR+sVvH2VPNy Wmd5X0Tz02o+Cmfo3azHXN+g/GYJCa1qAHxUKxqg79q9blj7mAO7MGdXXDPJsy7LA6yk WkFuFksxZpgr220ge3wupUYgq996l7mbIjgn9Jmm4ZBqU5ahoAK6lYL6Ff/WedJtR6eX igux2F1YPu+kScg5WMSruDOunYjhGDdSYbJaL1ojucpLpROu3EJd58QwFnp7chX5iUBx YEkDjVgMNyvhQRXcAXtsv9sewfewJC+D4pZIZk/rQR+8FZfqKePCDSkYtMmOUU7qey1g p5Bw== X-Gm-Message-State: AIkVDXKfyH9t+fDlMhOEXT9oMVczVehwZpG9F975MyIan7sWy44bwPt+mp7hdu7/zsjSvIzKjiYcl9QD6S1IcQ== X-Received: by 10.25.22.104 with SMTP id m101mr12992217lfi.17.1484690286163; Tue, 17 Jan 2017 13:58:06 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <2df480cc-5ef2-9ac6-b7ad-d17788a6b8b9@ecosensory.com> References: <2df480cc-5ef2-9ac6-b7ad-d17788a6b8b9 AT ecosensory DOT com> From: "David Carr (junk AT dcarr DOT org) [via geda-user AT delorie DOT com]" Date: Tue, 17 Jan 2017 15:57:25 -0600 Message-ID: Subject: Re: [geda-user] QFN packages solder mask To: geda-user AT delorie DOT com Content-Type: multipart/alternative; boundary=001a114015e21bcee7054651650e 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 Precedence: bulk --001a114015e21bcee7054651650e Content-Type: text/plain; charset=UTF-8 John, gerbv can remove elements from gerber files. I'd add your tiny metal specks to get the mask relief you want and then use gerbv to manually remove those specks from the metal layer after generating the gerbers. David On Tue, Jan 17, 2017 at 3:47 PM, John Griessen (john AT ecosensory DOT com) [via geda-user AT delorie DOT com] wrote: > I've been making footprints for QFN packages and came across guidelines by > the chip makers that say > it is beneficial to have some solder mask under the edge of the QFN > package, but not if it gets too thin > anywhere, as it can come off and cause trouble if it is. > > So I was wondering if there is any way to get zones of solder mask added. > PCB generates solder mask, > it does not define it directly, so I'm looking for a trick. > > I experimented with the thickness clearance and mask values in the pad > line of an element. > The sharp square corners of the mask layer cause problems at QFN package > corners. > > The reasons are graphically shown in these files: > > http://ecosensory.com/geda/qfn_lands_problem.png > http://ecosensory.com/geda/qfn_lands_problem_cure.png > > Is there a gerber editor to use? > > In a while, pcb-rnd will be probably able to handle solder mask directly > and go beyond > layer growing limitations of solder mask and clearance, but I need > something now. > > If fabs would let you, a speck of metal that would be gone in the etch > could have > solder mask opening and put it where I want it... > > Is > -- > John Griessen -- building field gear for biologists > Ecosensory Austin TX ecosensory.com > --001a114015e21bcee7054651650e Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
John,

gerbv can remove elements from ge= rber files.=C2=A0 I'd add your tiny metal specks to get the mask relief= you want and then use gerbv to manually remove those specks from the metal= layer after generating the gerbers.

David

On Tue, Jan 1= 7, 2017 at 3:47 PM, John Griessen (j= ohn AT ecosensory DOT com) [via geda-= user AT delorie DOT com] <geda-user AT delorie DOT com> wrote:
=
I've been making footprints for QFN pack= ages and came across guidelines by the chip makers that say
it is beneficial to have some solder mask under the edge of the QFN package= , but not if it gets too thin
anywhere, as it can come off and cause trouble if it is.

So I was wondering if there is any way to get zones of solder mask added.= =C2=A0 PCB generates solder mask,
it does not define it directly, so I'm looking for a trick.

I experimented with the thickness clearance and mask values in the pad line= of an element.
The sharp square corners of the mask layer cause problems at QFN package co= rners.

The reasons are graphically shown in these files:

http://ecosensory.com/geda/qfn_lands_problem.pn= g
http://ecosensory.com/geda/qfn_lands_probl= em_cure.png

Is there a gerber editor to use?

In a while, pcb-rnd will be probably able to handle solder mask directly an= d go beyond
layer growing limitations of solder mask and clearance, but I need somethin= g now.

If fabs would let you, a speck of metal that would be gone in the etch coul= d have
solder mask opening and put it where I want it...

Is
--
John Griessen -- building field gear for biologists
Ecosensory=C2=A0 Austin TX=C2=A0 ecosensory.com

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