[sdiy] SMD soldering technique

cheater00 cheater00 cheater00 at gmail.com
Fri Mar 24 05:53:41 CET 2017


What sort of magnification do you use when soldering under the mantis? What
about smd inspection?

On Fri, 24 Mar 2017 04:34 charlie wallace, <charlie at finitemonkeys.com>
wrote:

> i use solder paste with a water soluble flux, personally for me no
> clean is a pita especially if people have to handle the boards
> afterwards.
>
> drop the paste on the pad, drop the part on the paste, solder it with
> an iron, hot gun, or hot plate, use an  under-board heater to help
> with thermal shock and it makes a lot easier to work with too.
>
> i fill up a small syringe with a metal luer lock every so often, use
> that up and put the rest in the fridge.
>
> we use the amscopes that are around  $100 or under (they're often on
> sale), the R-P type,,though i have the trionocular boom one for when
> lots of work, and an ebay'd mantis which is awesome.
>
>
> On Thu, Mar 23, 2017 at 5:25 PM, cheater00 cheater00
> <cheater00 at gmail.com> wrote:
> > Thanks, I'll check out that flux.
> >
> > So you don't use any flux for the smaller parts? Does that work well at
> all?
> >
> >
> > On Thu, 23 Mar 2017 17:31 Vladimir Pantelic, <vladoman at gmail.com> wrote:
> >>
> >> congrats of going SMD, but I have to say I find your technique overly
> >> complex.
> >>
> >> what I do for 0603/0805 and SOT/SO parts:
> >>
> >> 1) apply solder (0.35mm, lead free Felder ISOCORE, 3.5% flux, no clean)
> >> to one pad, or diagonal pads if a larger IC
> >>
> >> 2) pick part with tweezers, reheat the pad with the solder and place the
> >> part
> >>
> >> 3) solder the other pad(s)
> >>
> >> 4) done.
> >>
> >> for smaller ICs like TSSOP I add some Edsyn FL22 flux to the pads, then
> >> solder them with the same 0.35mm solder and tip as above, using a $200
> >> stereo microscope (Amscope SE 400-Z, 10X)
> >>
> >>
> >>
> >> On 23.03.2017 09:00, cheater00 cheater00 wrote:
> >> > Hi,
> >> > I have recently bought an SMD learning kit to try out some techniques.
> >> > I've had some really good results that were stunning for a person who
> >> > tried real SMD soldering for the first time, so I thought I'd share
> >> > what I did and what I used.
> >> >
> >> > I got one that looks like this, but I think I got mine on Amazon:
> >> >
> >> >
> >> >
> https://www.aliexpress.com/item/DIYmall-SMT-SMD-Component-Welding-Practice-Board-Soldering-DIY-Kit-Resitor-Diode-Transistor-By-start-Learning/32776255634.html
> >> >
> >> > The 1206 were easy, as were the 0805 and 0603. Too bad they didn't
> >> > have smaller ones. I didn't have to use a microscope but I wear
> >> > contact lenses so my vision is OK. Good lighting was crucial (see by
> >> > the end of the email), as my eyes couldn't resolve the detail without
> >> > it. With the light the work was really comfortable.
> >> >
> >> > I've used my Hakko-clone soldering station Aoyue Int2903 with this
> >> > Hakko-clone T12 tip type JL-02:
> >> >
> >> >
> >> >
> https://www.aliexpress.com/store/product/Hot-Hakko-T12-Soldering-Tips-T12-JL02-Series-Iron-Solder-Tip-For-Hakko-Fx-951-high/1486111_32574864414.html
> >> >
> >> > The tip I used worked pretty good.
> >> >
> >> > I used AmTech Tacky Flux, model NC-559-V2-TF. I bought it from Insat
> >> > on http://www.bga-reworking.co.uk/. They have other good soldering
> >> > stuff so check them out. I made enough of an order that they sent me a
> >> > set of tweezers and cutters. The tweezers are ESD and very precise,
> >> > the cutters have really nice blades but the spring shifts around which
> >> > is annoying.
> >> >
> >> > It's important to buy the flux from an authorized distributor listed
> >> > on this page:
> >> >
> >> > http://www.inventecusa.com/reps---distributors.html
> >> >
> >> > You can find AmTech knockoffs nearly everywhere and obviously they're
> >> > not going to have the same chemical composition as the original.
> >> > Amazon has the knockoff, so does eBay. The flux is really important.
> >> >
> >> > I first put the board in a "helping hand" stand, although I am
> >> > awaiting the delivery of an inexpensive pcb holder vise. Does anyone
> >> > know where to get aligator clips for the helping hand that don't have
> >> > the teeth? Much rather rubber jaws or no teeth at all? That would be
> >> > so much better. I might put some heat shrink on these.
> >> >
> >> > I start soldering by applying a tiny amount of the flux to the board.
> >> > Then I'd add some Stannol SN60Pb39Cu1 to the pads. I have a 1.00mm
> >> > diameter 500g spool that'll last me, my children, and my children's
> >> > children a lifetime. I could use some finer solder though, maybe
> >> > 0.2mm, because 1mm really applies very quickly. I'm holding my
> >> > soldering iron in my right hand.
> >> >
> >> > Next I'll take a pair of ESD tweezers and, holding the tape in my
> >> > right hand, I'll pry it open with the tweezers and pick out the part.
> >> > I'll put it on the board and apply heat to the top pad with the
> >> > soldering iron, then to the other pad. The part will not have settled
> >> > yet, so once it's held securely by the joints I'll let go with the
> >> > tweezer and heat both pads alternating between them until the part
> >> > settles. If it needs pushing in place I'll use the tweezer or a
> >> > spudger. I'm going to buy a magnetic knife holder thing for my
> >> > tweezers and spudgers which should make the process easier.
> >> >
> >> > At this point the resistor pads will have gratuitous balls of solder
> >> > on them, so I'll remove nearly all of it with Pollin 1mm wick, order #
> >> > 840 030:
> >> >
> >> >
> >> >
> http://www.pollin.de/shop/dt/OTY5OTUxOTk-/Werkstatt/Loettechnik/Entloetgeraete/Entloetlitze_1_0_mm_1_5_m.html
> >> >
> >> > it comes out of the spool condensed so I twist it around until it
> >> > separates into a mesh. This way it'll absorb much more solder for the
> >> > same length.
> >> >
> >> > At this point I might have to realign the resistor so I'll use some
> >> > heat and a spudger. I use these spudgers:
> >> >
> >> >
> >> >
> https://www.aliexpress.com/item/6Pcs-Hand-Tool-Professional-Steel-Solder-Assist-Electronic-Components-Repair-Welding-Auxiliary-Tools-Set-FULI/32780051115.html
> >> >
> >> > or at least ones that look the same. I don't know where I bought them
> >> > any more. ("Welding" is Aliexpress for "Soldering" and "Auxiliary
> >> > tool" is for "accessory", useful when searching for something)
> >> >
> >> > The flux makes all the difference. I did the first resistor with the
> >> > flux, and it worked well. I did the neighbouring one without applying
> >> > flux, I just used flux from the previous one, and that was pretty good
> >> > too. I tried the third pad watching out not to apply any flux, and the
> >> > results were really bad. As soon as I applied a little flux the joints
> >> > cleaned up, and the resistor applied well. The flux also smells really
> >> > nice. I later cleaned it off with some 70% ethanol and normal q-tips.
> >> >
> >> > I don't have a good light set up yet so during the process I used the
> >> > Black Diamond Revolt head-mounted lamp which I bought several years
> >> > ago, use all the time, and it remains like new.
> >> >
> >> >
> >> >
> http://blackdiamondequipment.com/en_US/headlamps-and-lanterns/revolt-BD620613_cfg.html
> >> >
> >> > It has an adjustable angle mount which was very important for
> soldering.
> >> >
> >> > The nice thing about this soldering technique is that it gave me
> >> > really perfect results without much of a fight. I might still have to
> >> > practice to leave more solder on the pads, but the initial results are
> >> > very promising.
> >> >
> >> > The one improvement I'd like is a different tweezer. A sideways
> >> > tweezer would be better, where the jaws curve in on themselves out of
> >> > the plane of the sheet metal the tweezer is made of. I haven't been
> >> > able to find one with a nice angle (say 75 degrees) and a fine tip and
> >> > ESD coating. If anyone has a suggestion, I'd love to hear about it.
> >> >
> >> > After cleaning with 70% ethanol, the board still seems to have a bit
> >> > of a film on it, so if someone has a suggestion for a better solvent
> >> > for the AmTek flux, let me know please.
> >> >
> >> > Hope this helps someone. If not, at least I had fun documenting what I
> >> > did in case I forget in the future :)
> >> > _______________________________________________
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> >> >
> >>
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