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=gmail.com; s=20161025;
        h=mime-version:in-reply-to:references:from:date:message-id:subject:to;
        bh=LPgHwYPW7qqU9gmC6RnIoRZlCpeV+G6XgqjFoLYSNfo=;
        b=LZFk2zH6UutAxSlTLfqxR1CKajVn0fgNGSNVDKSKeM1sH+VPULJR8CU+a5p0chWhqu
         gsCyBM3yCI0VWOyKA4SyTISg9bMX5VjpgQ49p9PXLG5Uvk0YrGSKL2VOpKCQR3v0FinD
         BvhZZc/CViJf+TZkVBdD2NehwNrHKeVYY/wZUheXMlTpdcvML/d6UyXaerBQR+cn2nWB
         4xsVofSc0FHhncuJ5unvwJN7SJ4EtUH0fBL/fp594Eq6dswiOefBnqAHLzI4JSFvoe/a
         PdAxT/Oo0tneTItxEntbY9lEublmxYZYxLx8lqwmJ/Yjr0sugXCT0Hdprbm2wZKhcDCk
         jjNg==
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=LPgHwYPW7qqU9gmC6RnIoRZlCpeV+G6XgqjFoLYSNfo=;
        b=Of5Y5Y9het5fvtBrOi4TtGDFvsSP7tAU2OpK8swrMvgUQBGcGbo5K9yucvXwStKDQG
         kyhZOwY+7nEwMnGJB8rN2Tni6hLIx7EExu5Y/ozRBkBbFTm6Qrpa7qLQCcxwBucEcKwZ
         AnaAk5caDhmWBuxAHPEcIjYNXumcfSuabB6VMqCtEhXhhpVwbs1wJwmmI0ysUvM1/GZS
         FY70Gto8PBv4B0Q1wUTqRIT0YZBfrcGZdprl+0VDfD2BUwmpd+ztadhIB9E6yeaRUpBd
         v7SGxlzYMmimmTpWo9VFVzOmg9/JeDUcoyuxnVDTvw346cKyi+ssODuiNs+pVDyH22+j
         Qfug==
X-Gm-Message-State: AFeK/H3GBV/y2LdfR91sPe8Jryw2sxzQYbJyCrE1aO+v9tWlKIqK3pMjImTqMJzPpRo1kMHWYcKqF6lsX004DA==
X-Received: by 10.157.16.120 with SMTP id o53mr21769946oto.261.1490220933313;
 Wed, 22 Mar 2017 15:15:33 -0700 (PDT)
MIME-Version: 1.0
In-Reply-To: <20170322210114.08D208106DD0@turkos.aspodata.se>
References: <20170322172551 DOT DF40C8106DD0 AT turkos DOT aspodata DOT se>
 <201703221400 DOT 51991 DOT gheskett AT shentel DOT net> <20170322210114 DOT 08D208106DD0 AT turkos DOT aspodata DOT se>
From: "Erich Heinzle (a1039181 AT gmail DOT com) [via geda-user AT delorie DOT com]" <geda-user AT delorie DOT com>
Date: Thu, 23 Mar 2017 08:45:32 +1030
Message-ID: <CAHUm0tOOZm8RoJgi37PyObp71bJtxEJ3=dWFwVWvgNUyJDNcdg@mail.gmail.com>
Subject: Re: [geda-user] handsolder QFN packages
To: geda-user <geda-user AT delorie DOT com>
Content-Type: text/plain; charset=UTF-8
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

I've had success reflow soldering with a simple lift-off jig made from
bits and pieces lying around to gently lift the reflowed board away
from the hot plate at around 280 seconds.

The key features are a ~3mm thick plate to spread the heat, having the
800W hot plate starting at ambient remain on for 250 seconds, then
turned off, then lifting off the board with the jig at about 280
seconds, to get a really good fit to the recommended JEDEC heating
curve.

http://vk5hse.blogspot.com/2011/05/finishing-off-sdr-cube-transceiver.html

being able to lift the board without jostling at 280 seconds avoids
the problem of thermal inertia of the hot plate continuing to heat the
board longer than necessary. I usually just chock the jig after
lifting it away from the hot plate.

for a tiny board, slightly less than 250 seconds may be sufficient,
and can be judged by the solder paste elsewhere going from grey to
shiny.

I started with a thermocouple, but the process is so predictable you
really only need a clock that shows elapsed seconds.

Cheers,

Erich.