[time-nuts] Vaperware Parts and pulse stretching circuits

[Bob kb8tq]

Hi

Metcal’s are great soldering setups. They also are *expensive* soldering setups. 
I mumble and grumble each time I do a re-stock on tips. I know of several plants 
that tooled up on Metcal’s and then switched to something else after a few years.
The issue was never performance. It always was cost.

Bob

> On Apr 25, 2020, at 8:38 PM, Bill Notfaded <notfaded1 at gmail.com> wrote:
> 
> I totally agree with the Metcal soldering station!!!  I'll never go back to
> anything else.  I don't even use a scope.  I bought some magnifying glasses
> with 5 sets of different power lenses you wear like glasses.  It has built
> in led light and adjustable strap that hold it on your head off Amazon.
> Works great.  I can do all small surface mount stuff with them.  Plus I
> have my normal vision and hand eye coordination going that way.  Soldering
> under a scope or on a video monitor is a lesson all in itself!
> 
> Bill
> 
> On Sat, Apr 25, 2020, 6:15 AM Gerhard Hoffmann <ghf at hoffmann-hochfrequenz.de>
> wrote:
> 
>> 
>> Am 25.04.20 um 13:41 schrieb John Ackermann:
>>> I do have a microscope (cheap Chinese unit, maybe $400 with articulated
>> arm and the works) and it does make things much easier.  But as long as you
>> can see the work, you can do the job.
>>> 
>>> It's not that hard to do small pitch parts.  I usually do the best I can
>> soldering individual pins, knowing their will be bridges, then clean up
>> with solder wick and *lots* of no-clean flux.  You can never have too much
>> flux.  I've found a 1.6 mm chisel tip is a good all around size for SMD
>> work, though I have a 0.8 mm chisel available for when things get tight.
>>> 
>>> The hardest part is getting the first couple of pins tacked down so the
>> part is square on the pads.  After that it's fast.
>>> 
>>> John
>> 
>> I have about the same here, plus a cheap Chinese Ayoue852 hot air
>> station. Exchanging the Weller for a Metcal was the biggest improvement
>> after the LED ringlight for the microscope.
>> 
>> In my quest to scrutinize the 1/f region, I have built some chopper
>> amplifiers and the newest one will have GaN transistors that are nekkid
>> chips with jut 4 tin bumps below. No case, just the passivated chip, 1 *
>> 1 mm, EPC2038. Low channel resistance, even lower capacitance -> low
>> charge injection. Resistors are 0603.
>> 
>> Fearing I could not handle them, I made a minimum version of the switch
>> itself as a test structure in an unoccupied corner of a different
>> project. But soldering did take just 3 minutes, it was surprisingly
>> easy. Just keep the air flow low enough, or you will have trouble to
>> find the chips again. The thick-liquid flux helps to fix the chips in
>> place.
>> 
>> Legible part numbers on the board are hopeless at this scale. The board
>> was made by PCBway, there were some discussions about having solder mask
>> ON part of the pads, and some discussions with our German customs that
>> you cannot buy 10 boards for $10 or so.
>> 
>> The chips are the gray squares between the 2 vias on the left and the 4
>> huge coupling capacitors.
>> 
>> Cheers, Gerhard
>> 
>> 
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