[sdiy] pros and cons of SMT in DIY

Mon May 22 00:58:34 CEST 2017

Nice, sounds interesting. How do you connect it to a display for minimum
lag?

On Sun, 21 May 2017 21:36 charlie wallace, <charlie at finitemonkeys.com>
wrote:

> convert it to m12
> https://www.peauproductions.com/collections/playstation-eye-accessories
> then you can use a wide variety of m12 lenses  there are some 3d
> printable setups on thingiverse but they're not great.
>
> i'd give you a specific one, but i use my ps3 eye for a different
> setup, it is not really that hi res, but the frame rate is much better
> 640 x 480 at 60fps which i find better to work with than the slow usb
> microscope cameras that are usually very laggy though with a higher
> speed, i'll grab some pics and share of the quality once i'm finished
> building these 500 pcbs ;)
>
> cheers
>
>
> On Sun, May 21, 2017 at 4:27 AM, cheater00 cheater00
> <cheater00 at gmail.com> wrote:
> > Yeah i know you can put th footprints on a board you'll populate with
> smd,
> > that's the whole point. I posted about this here maybe 10 years ago
> already.
> >
> > Good to know about the experiences with magnet wire. Thanks.
> >
> > Charlie what lenses do you suggest for the ps eye? Do you have video
> demos?
> >
> >
> > On Sat, 20 May 2017 18:59 charlie wallace, <charlie at finitemonkeys.com>
> > wrote:
> >>
> >> a few of us are putting together 400 boards this week/end, it is
> >> mostly smd 0805 with lqfp (which i personally dislike but i was
> >> outvoted, i prefer qfn since it solders better)
> >>
> >> we have a stencil printer
> >>
> >>
> http://www.ebay.com/itm/332130477725?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
> >> it is not great but once you get it dialed in it works, in the past we
> >> just put hinges on a piece of MDF and the stencil, then cut out an
> >> outline of the pcb to be made , and use those as guides
> >>
> >> the stencil comes from the pcb people or we laser cut or cnc one out,
> >> these are generated from the tcream layer in eagle, with cheap ebay
> >> 40w laser i use the engrave method rather than cut , it gives better
> >> edges; if i cnc then i use brass shims, usually 3mil and i schrink the
> >>  tcream a little first.
> >>
> >> the paste is applied using a thin spring steel metal scraper that i
> >> used for clay sculpting, it works the best of anything i've found so
> >> far, i use aim leaded water soluble solder the no clean stuff is no
> >> good for these boards, and its a nightmare to clean if you have too
> >>
> >> then to a small pnp the neoden tm220a, though wish i'd gone for the
> >> 240a at the time (bought by generating litecoins with old gpus a few
> >> years ago) there is a nice ulp dp-tm220a.ulp that handles it, once its
> >> up and running it does pretty good but not a lot of components can fit
> >> it, we have a modified juki as well but its in storage.
> >>
> >> once as many parts as the pnp can place, the board goes into the
> >> kitchen and the others place the few smd components, and then it goes
> >> on to the madell hot plate, for a 170o cycle, after the thru hole
> >> parts are added with the metal under either the amscope microscopes or
> >> the mantis (all ebayed or bought from amscope directly during sales)
> >>
> >> then the board is de-briged if needed, usually the lqfp arm chips
> >> since this time i let the board house do the stencil gerber and they
> >> didn't shrink it.
> >>
> >> there are about 60 parts placed, the good thing about smd is that part
> >> placement only has to be pretty close, the surface tension of the
> >> solder will pull the parts in (usually)
> >>
> >> with two of us we can do about 10 boards an hour at a relaxed pace,
> >>
> >> qfn's i like since you can practically throw them onto the board and
> >> they'll self right, and they tend not to bridge, we did a test where
> >> we could see how lax the part could be placed and it'll still solder
> >> in properly.
> >>
> >> smd size doesn't really matter if you're hot plating, once you get
> >> down to like 0201 and such its all about magnification and a steady
> >> hand, and if you don't have that then use a manual xy pick and place
> >> tool, or an automatic one. manually soldering them is also straight
> >> forward you can glue them in place then solder if you're not steady, a
> >> small tipped iron with the right temperature it goes well , takes a
> >> little bit of practice on how best to hold them and avoid tombstones
> >> if not glued, again you can also use the xy tool to place and hold a
> >> part while you hand solder it.
> >>
> >> we've taught 100s of people to smd aver the years, some have never
> >> even picked up an iron before and they're placing chips, 0602s with no
> >> bother , though occasionally people have soldered chips upside down
> >> before ,another good argument for qfn
> >>
> >> basically you just need a good iron, good microscope (amscope rp type
> >> is fine) i'd avoid most usb microscopes since too much lag so hard to
> >> solder and stick to glass, but you can $5 a playstation eye , mod the
> >> lense and and get an ok picture at 180fps, flux and a 10/5ml tube of
> >> solder paste.
> >>
> >>
> >>
> >> On Sat, May 20, 2017 at 8:15 AM, Richie Burnett
> >> <rburnett at richieburnett.co.uk> wrote:
> >> > Paula, when you say "working with 0402", do you mean replacing the odd
> >> > component here and there, or soldering 100s of SMT parts on?  And how
> >> > are
> >> > you actually doing the soldering?  With a fine tipped soldering iron
> and
> >> > a
> >> > steady hand?  ...heater tweezers?  ...or stencilling solder paste onto
> >> > the
> >> > board then placing components into the paste and ovening the board?
> >> > Just
> >> > curious what methods you're using, particularly to get consistent
> >> > results
> >> > with those tiny QFNs.
> >> >
> >> > I can also vouch for the structural integrity of super-gluing down
> >> > wire-wrapping wire or polyurethane enamelled copper (magnet wire) for
> >> > mods
> >> > to PCBs.  Never seen one fail, and they're almost impossible to rip up
> >> > if
> >> > you need to.  I've never felt entirely happy with the fumes given off
> >> > when
> >> > someone has to solder in an area of the board polluted with dried
> >> > Cyanoacrylate glue though.  I remember doing this once and leaping
> >> > backwards
> >> > with my eyes and nose stinging!  Can any of the chemists on this list
> >> > comment on what vapours are liberated when a hot soldering iron
> touches
> >> > cured Cyanoacrylate glue?  (I appreciate that I should already have
> been
> >> > soldering in an area with positive airflow away from me, extraction to
> >> > outdoors, etc...)
> >> >
> >> > -Richie,
> >> >
> >> > -----Original Message----- From: paula at synth.net
> >> > Sent: Saturday, May 20, 2017 3:45 PM
> >> > To: cheater00 cheater00
> >> > Cc: Synth DIY
> >> > Subject: Re: [sdiy] pros and cons of SMT in DIY
> >> >
> >> > On 2017-05-20 03:42, cheater00 cheater00 wrote:
> >> >>
> >> >> Yes, a TH pcb will be able to hold a daughter pcb just by the
> >> >> through-holes, whereas SMD pads will not hold one. So you can easily
> >> >> change topology using an extra pcb on a TH circuit but not on an SMT
> >> >> circuit.
> >> >
> >> >
> >> > You know you can use both SMT and through hole if you need?
> >> > My current project for work has around 100 SMT parts, and 7 through
> >> > hole, some of which are for PCB interconnect.
> >> >
> >> > At the end of the day, the choice is up to the designer.
> >> > I'm really comfortable working with 0402 and QFN (3mm x 3mm) packages,
> >> > and with modding them with mod wires if needed (for the record super
> >> > gluing a mod wire makes it rock solid).
> >> > I'm considering trying 0201 for some parts, just as a personal
> challenge
> >> > :)
> >> >
> >> > So it's up to each person.
> >> > There's no "right or wrong" or "this way is better", it's just
> >> > different.
> >> >
> >> > Paula
> >> > _______________________________________________
> >> > Synth-diy mailing list
> >> > Synth-diy at synth-diy.org
> >> > http://synth-diy.org/mailman/listinfo/synth-diy
> >> >
> >> > ---
> >> > This email has been checked for viruses by AVG.
> >> > http://www.avg.com
> >> > _______________________________________________
> >> > Synth-diy mailing list
> >> > Synth-diy at synth-diy.org
> >> > http://synth-diy.org/mailman/listinfo/synth-diy
> >> _______________________________________________
> >> Synth-diy mailing list
> >> Synth-diy at synth-diy.org
> >> http://synth-diy.org/mailman/listinfo/synth-diy
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://synth-diy.org/pipermail/synth-diy/attachments/20170521/dc3a5517/attachment.htm>