X-Authentication-Warning: delorie.com: mail set sender to geda-user-bounces using -f X-Recipient: geda-user AT delorie DOT com X-Virus-Scanned: Debian amavisd-new at mail.linetec.nl Content-Type: multipart/alternative; boundary="------------9tpvhgy6InIiZl9WfzRqXOLT" Message-ID: <80ec108f-40ab-647a-bee7-4f846c169fad@linetec.nl> Date: Fri, 19 Aug 2022 11:31:08 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.11.0 Subject: Re: [geda-user] [OT] Solder paste woes Content-Language: en-US To: geda-user AT delorie DOT com References: <66c88bcb-820c-9a1d-1698-d0b36f32e3f3 AT linetec DOT nl> From: "Richard Rasker (rasker AT linetec DOT nl) [via geda-user AT delorie DOT com]" In-Reply-To: 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 This is a multi-part message in MIME format. --------------9tpvhgy6InIiZl9WfzRqXOLT Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Almost missed this one: Op 17-08-2022 om 14:59 schreef Erich Heinzle (a1039181 AT gmail DOT com) [via geda-user AT delorie DOT com]: > Two thoughts > > 1) I have heard of many people doing reflow at home who use locating > pins on a precisely drilled support block that positively locates the > pcb itself and the overlying stencil with matching holes when applying > the paste > > 2) It could be that your apertures in the stencil are not optimal. > Smaller apertures may allow more precise results. IIRC gEDA PCB solder > mask aperture shrinkage relative to the pad shape can only be defined, > if at all,  on a whole board basis. > > pcb-rnd treats each pad as a padstack,  where layer apertures on each > layer can be defined individually,  or autogenerated, in the > :padstackedit action. > > Identical pads, i. e. in a QFN,  can use the same padstack prototype > for all the pads,  once defined. This gives you very granular > control,  down to the individual padstack if required. Slots and > arbitrary simple polygonal pad shapes are also supported in padstacks. > > How are you generating your gerbers for the stencil? I use pcb's export function in a shell script I wrote: pcb -x gerber $projname.pcb (This script also collates the gerbers and xy files into a zip file, and sorts and converts the bom into a format that I can import in a LibreOffice spreadsheet.) A switch to pcb-rnd is tempting, as it offers more control and richer features, and I have tried it out in the past -- however, there are several reasons for me to stick with pcb, including familiarity and compatibility with some colleagues of mine (who also use pcb). I'll take another look at pcb-rnd, and see what I can do with regard to stencil apertures (I noticed that many PCB houses automatically split up large single holes into multiple smaller ones) -- but first, I'll focus on the mechanical set-up and workflow here, because I think that is the biggest cause of my problems. Regards, Richard --------------9tpvhgy6InIiZl9WfzRqXOLT Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: 8bit

Almost missed this one:

Op 17-08-2022 om 14:59 schreef Erich Heinzle (a1039181 AT gmail DOT com) [via geda-user AT delorie DOT com]:
Two thoughts

1) I have heard of many people doing reflow at home who use locating pins on a precisely drilled support block that positively locates the pcb itself and the overlying stencil with matching holes when applying the paste

2) It could be that your apertures in the stencil are not optimal. Smaller apertures may allow more precise results. IIRC gEDA PCB solder mask aperture shrinkage relative to the pad shape can only be defined, if at all,  on a whole board basis. 

pcb-rnd treats each pad as a padstack,  where layer apertures on each layer can be defined individually,  or autogenerated, in the :padstackedit action.

Identical pads, i. e. in a QFN,  can use the same padstack prototype for all the pads,  once defined. This gives you very granular control,  down to the individual padstack if required. Slots and arbitrary simple polygonal pad shapes are also supported in padstacks.

How are you generating your gerbers for the stencil?

I use pcb's export function in a shell script I wrote: pcb -x gerber $projname.pcb

(This script also collates the gerbers and xy files into a zip file, and sorts and converts the bom into a format that I can import in a LibreOffice spreadsheet.)

A switch to pcb-rnd is tempting, as it offers more control and richer features, and I have tried it out in the past -- however, there are several reasons for me to stick with pcb, including familiarity and compatibility with some colleagues of mine (who also use pcb).

I'll take another look at pcb-rnd, and see what I can do with regard to stencil apertures (I noticed that many PCB houses automatically split up large single holes into multiple smaller ones) -- but first, I'll focus on the mechanical set-up and workflow here, because I think that is the biggest cause of my problems.

Regards,

Richard

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