[hpsdr] Bare Boards

[Philip Covington]

Hi all,

Here is a quick list of the equipment I use for soldering.  I have not
found anything that I would not attempt yet.

Weller WES51 Soldering Station - approx $120
Weller ETS tip - approx $5
Fine curve tip tweezers - approx $15
Dental Pick set - approx $15
Stereo Boom Arm Microscope (5x-10x) - approx $275
Toaster Oven - approx $30
Hot Air Gun (1" dia nozzle) - approx $20
Dwyer Temperature Controller w/ thermocouple - approx $30 used
Halogen lamp - approx $20
Anti-static work mat - approx $25
Dental mirror - approx $5
Kester No-clean flux pen
Kester Water Soluable Flux
Kester No-clean solder paste

I use the dental picks for inspection.  By dragging the dental pick
across the pins of the fine pitch parts I can quickly hear if there is
a bad solder joint.

I also use one of the dental picks as an electrical probe when debugging.

I use the dental mirror for inspecting the sides of components,
especially QFN leadless stuff.  I use the dental mirror under the
microscope at a 45 degree angle.

The hot air gun is great for removing one component.  I shield the
rest of the components with heavy duty aluminum foil and place the
thermocouple probe right at the component I want to remove.  I space
the heat gun about 1.5 " away from the part to be unsoldered and watch
the temperature.  When it reaches about 225 C, I remove the part by
tapping it with the dental pick.  The above procedure also works well
for soldering the QFN parts.  If I have more than one to do I use the
toaster oven instead with the same temperature probe.  I manually
modulate the temperature to follow the Kester solder paste profile.

I have enough patience to do at most one or two boards myself - but
pretty much only for the initial development and prototyping.  After
that, it becomes boring and too much like work - then I'd rather buy
an assembled board.

73 Phil N8VB



On 2/16/07, Bill Tracey <bill at ewjt.com> wrote:
> ***** High Performance Software Defined Radio Discussion List *****
>
> I'll admit to being surprised at the amount of interest in bare boards,
> turns out to be running a bit higher than I'd expected it would be.
>
> I'd be interested to hear from the folks looking at the bare board option
> their reason for going that route.  Is it a cost issue?  Or really want to
> know the technology and figure building the board helps in getting to know
> how it works?   The ship building feeling one gets putting something like
> this together?
>
> I'll admit I like building these things.  Having built two sets of these
> and done major repair work (FPGA replacement) on one, I'll happily go the
> built and tested route on this round of boards.    As others have pointed
> out, these are not beginner SMT boards.   The first set I did,  I did w/o a
> microscope using a fine tipped iron.  Doable but right at the margin of my
> skills w/o a microscope.   The 2nd set I did with a microscope and a mix of
> fine tipped iron and hot air and paste technique - this one was much easier
> with the microscope - I'll never consider doing 100+ pin 0.5mm pitch parts
> w/o a microscope ever again.     The other parts on the board that are
> somewhat troublesome to hand assemble are some of the resistor packs which
> are a leadless package (Personally, I do hope there's a special place in
> hell for the geniuses that came up with leadless packages)
>
> I don't mean to discourage anyone from going the bare board route if that
> is what they want to do.  Just interested in folks reasons for building
> their own and want to make sure folks are aware how small/tight pitched
> some of the parts are.     Actually I'd hope to recruit some of the folks
> with the skills and tools to build this kind stuff by hand to get involved
> in some of the future projects.
>
> Cheers,
>
> Bill  (kd5tfd)
>
>
>
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