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From: "karl AT aspodata DOT se [via geda-user AT delorie DOT com]" <geda-user AT delorie DOT com>
To: geda-user AT delorie DOT com
Subject: Re: [geda-user] [OT] Solder paste woes
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References: <66c88bcb-820c-9a1d-1698-d0b36f32e3f3 AT linetec DOT nl>
Comments: In-reply-to "Richard Rasker (rasker AT linetec DOT nl) [via geda-user AT delorie DOT com]" <geda-user AT delorie DOT com>
   message dated "Wed, 17 Aug 2022 13:15:47 +0200."
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Date: Wed, 17 Aug 2022 14:21:52 +0200 (CEST)
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Precedence: bulk

Richard Rasker:
...
> My main problem is that even after hundreds of PCB's, the result is 
> unpredictable. Only 2 out of every 10 PCB's have a good crisp result, 
> like this: http://www.linetec.nl/electronics/paste_crisp.jpg
> 
> The other PCB's often look like this: 
> http://www.linetec.nl/electronics/paste_mess.jpg
...

This is what I noted:
. there are more lint strands in the "mess" one
. on some paste lands there is evidence of it sticking to the stencil
. on U2 the paste don't align with the cu-lands
. on the D2 andD3 silk, at the hole, there is some surplus paste,
  same on U6 bottom left hole inside the courtyard silk
  same to the left around the "+" silk sign
  some on the hole below U6's left side
. overall on the "mess" one, the alignment is bad

So, has there been movements and perhaps better cleaning will help ?

Also, if you store the paste in the refrigerator, it will get more
fluid when it heats up, so perhaps a more thick paste that you
will allow to heat up before use to lessen the differents between
pcb's.

Regards,
/Karl Hammar