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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