Flux is - or used to be - rosin dissolved in alcohol. You can take a bottle
of Radio Shack Flux and dilute it as you like with alcohol. I take it
straight. Tough guy! I use a spent syringe with the needle removed to
squirt flux on my boards. Then a tuna can with plastic top with more
alcohol in it to flush the board flux off.
You should be just fine. I would recommend getting into SMD stuff. You
sure can make a large schematic in a small board! I am now all SMD and
boards are much smaller. Except I have lots of LM324s that eat up board
space!
Larry
-----Original Message-----
From: Electronics_101@yahoogroups.com
[mailto:Electronics_101@yahoogroups.com] On Behalf Of Banibrata Dutta
Sent: Sunday, December 02, 2012 12:41 PM
To: Electronics_101@yahoogroups.com
Subject: Re: [Electronics_101] Re: DMM, continuity test - on soldered uC
Thank you, Larry and Richard. That is very reassuring. The flux variety I
have is the fairly thin liquid kinds, and not the more gel (probably thicker
/ more viscous) type ones seen in many videos. Could this matter ?
Since the uC in question is only available in TQFP, I'd to take the SMD
route. I hope to use through-hole components for everything else on the
board. Hoping that it works.
On Sun, Dec 2, 2012 at 10:52 PM, rtstofer <rstofer@pacbell.net> wrote:
> **
>
>
>
>
> --- In Electronics_101@yahoogroups.com, Banibrata Dutta
> <banibrata.dutta@...>
> wrote:
> >
> > Wanted to check if it is okay to check for good solder contacts, by
> > doing the standard DMM continuity test between the uC pins, and the
> corresponding
> > breakout board header pin ? Or can it damage the IC in some way ?
> >
> > cheers,
> > BD
>
> I would make certain that the RED lead of my DMM went to the pin and
> the BLACK lead went to the trace. At least this would keep the
> polarity straight.
>
> Most uCs have pin voltage protection using Schottky diodes between the
> pin and ground as well as between the pin an Vcc. I wouldn't want to
> reverse bias them.
>
> I would put my DMM on the Ohm mode. I just connected the DMM in Ohms
> mode to another DMM in Volts DC mode and came up with just 0.7V. I like
that!
> Barely enough to forward bias a diode. In the other modes (nS, Buzzer
> and Diode Test), the voltage across the probes was 5V.
>
> I could see drag soldering a 64 pin device, it's pretty easy. But if I
> had other 0805 components, I would use solder paste and a hot plate.
>
> Make sure you have plenty of SolderWick in a couple of sizes. I
> usually apply even more flux if I have to break up a solder bridge with
SolderWick.
>
> Richard
>
>
>
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