[time-nuts] Soldering small stuff...

[Forrest Christian (List Account)]

So a couple of notes from here:

I solder 0.5mm pitch TQFP's on a fairly regular basis with just a
reasonably-sized chisel tip and plenty of flux.   I often will end up with
just a bit at the end of surplus which wick will pull off.    I actually
have done this on the bench with a $100 hakko FX601 and a questionable
tip.  So nothing to worry about.

As my eyes have aged, I don't see small things or far away things all that
well.   I have discovered a slightly overpowered set of reading glasses are
perfectly adequate to look at a fine pitched TQFP to determine if there are
bridges.   I do have a couple stereo microscopes available to me, but I
typically prefer the glasses unless I need to look very closely at the work.

On Sun, Apr 26, 2020 at 12:28 AM Charles Steinmetz <csteinmetz at yandex.com>
wrote:

> Burt wrote:
>
> > I have an AM-SCOPE 7-35 magnification stereo microscope. I also have an
> > OptiVisor with a 5x stereo lens that my son gave me about 10 years ago.
> > As nice as the microscope is, I generally wind up using the OptiVisor.
>
> Optics:
> OptiVisors are *great*.  But there are lots of poor-quality imitations
> out there.  Accept no substitutes!  Buy Genuine Donegan OptiVisors
> *only*, with "DA-" series glass lens plates (blue lens frames) -- *not*
> the "LX" series with acrylic lenses in clear lens frames.
>
> The one drawback of OptiVisors is that if you want higher power you have
> to settle for reduced working distance.  At some point, I don't really
> want my face that close to the hot iron and solder vapors.  For
> soldering, I find the DA-5 lens plate (2.5x at 8" working distance) is
> my practical limit.  A good stereo microscope (with reduced-power barlow
> lens) solves this problem.
>
> BTW: Even 7x is *way* too much power for comfortable use as a soldering
> magnifier, IMO. You might want to try a 0.2x to 0.3x Barlow lens, such
> as the AmScope model SM03, which could make the experience much nicer.
> And possibly some lower-power eyepieces.
>
> So:  How about a wearable version of the stereo microscope (best of both
> worlds)?
>
> Those are called "surgical loupes."  And they are a pure joy to use.
> Once you try a pair of properly fitted and collimated surgical loupes,
> you will never go back to anything else for soldering small parts.
>
> However: surgical loupes are moderately to very expensive, and it's hard
> to economize by buying used because they really need to be fitted and
> adjusted by an optician who knows what (s)he is doing or you may have
> eyestrain using them.  If you are optically knowledgeable and can figure
> out the misalignments for yourself (say, if you have sucessfully
> collimated a few pairs of binoculars), it is possible to self-fit them.
>   *Note* that the collimation problem arises with stereo microscopes as
> well -- many of the old venerable models you find used (B&L, AO) are
> badly out of alignment.
>
> Soldering:
> Finally, there is no need to flood IC pins with so much solder that you
> need solder braid to remove it.  The secrets are (1) use the right iron
> tip (a flat or slightly concave bevel tip is one of the best, but a
> spade will work); (2) keep the tip surgically clean; (3) keep the tip at
> the right temperature; and (4) use quality solder with plenty of flux.
> To see it done right (in less than 3-1/2 minutes), watch:
>
> <https://www.youtube.com/watch?v=5uiroWBkdFY>
>
>
> Best regards,
>
> Charles
>
>
>
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-- 
- Forrest