How to crimp and solder connectors properly.

[ex-Gooserider]

The biggest thing to remember is that you want an electronics flux, NOT an "ACID" flux... If they recommend it for plumbing, you do NOT want to use it on electrical stuff, and vice versa... Ditto for the solder - "rosin core" is fine, "acid core" is not...

Once you get into electronics fluxes though, there are some extra points... The brown stuff that BM pointed to is a traditional rosin flux, which works, but can be a real pain to clean, and really should be cleaned off after soldering. The problem is that many of the solvents that remove it most effectively ARE banned, or tightly restricted. Rubbing alcohol does work to take it off, but slowly...

They now also make clear water-based fluxes that work just as well (at least on pc-board electronics), and are intended to be cleaned with just plain water... Mostly I just use rosin core solder, so I haven't really tried both, but I know that many of our electronics guru's swear by the water based stuff, and AT the rosin stuff... In one case it's a guy that specializes in doing ultra fine pitch SMD stuff, who says the rosin fluxes give problems with small SMD components with leads that go under the chip (BGA's among others) as it is very hard to get them cleaned out afterwards, where the water based ones aren't as hard to deal with...

ex-Gooserider

[flagman1776]

I was just making my solder splices tonight... I see I still have several rolls of fine cored electronics solder... I hope I don't have trouble replacing it.

[LROBBINS]

To complicate it further, there are even more classes of electronics soldering fluxes:

traditional rosin flux
no-clean flux (a flux that can be left in place in most applications)
water-soluble flux (easier to remove if you want to remove it)

all 3 are available for lead/tin or lead-free solders

all 3 are available as paste or liquid, and at least no-clean and water-soluble are also available as "sticky" formulations that I like for doing SMD (I'm less likely to move the stuff while getting it into an oven). Some people just dissolve violinist's rosin (or even resin from pine cones) in alcohol. Haven't tried that yet.

Most people doing a lot of SMD like to use paste solder, which is finely ground solder in flux. Unfortunately, unless refrigerated it has a short shelf life, though I'm not sure that this really matters if you also use a bit of liquid flux. It's often shipped overnight on ice, which gets pretty expensive. One industrial outfit I know of uses liquid flux and powdered solder.

I've come up with my own scheme for SMD that avoids using paste solder, hot-air re-work guns, and hand soldering. I use a very fine gauge (0.4mm, 0.015") 63/37 lead-tin Kester no-clean flux solder wire. Using smooth jaw needle nose pliers, I gently flatten a strip of it so that it won't roll about. I then cut it into strips a bit longer than the entire series of the pins of an IC, or a bit longer than the length of a discrete component. (I cut enough strips for a couple day's work and store them in a clean container.) I then put a bit of no-clean tacky flux (made for lead free, but fine for lead) on all the pads on the board. I then lay the solder strips for a few components, tacky flux the component pads, and position the piece with fine forceps under a stereo microscope (a magnifying glass or very good eyes would do, I just happen to have a scope available). Once all the parts are positioned, I transfer the board to an ordinary toaster oven (the absolute cheapest that I could find at amazon.it - NOT TO BE USED FOR FOOD!).

The oven thermostat is then set at 105o C for 15 min to 1/2 hour to drive off any absorbed water, raised to 125o for another 15 minutes (even 85o use-rated components are rated at least 125o for storage). I then turn it up to ca. 200o for 5 minutes, and finally turn the oven to max and watch for when the solder starts to melt. In about 15 seconds the solder starts to flow by capillary action, wetting out the pads and disappearing from between them, and after 30 seconds I turn the oven off and leave it gently cool for a few minutes before opening the door.

With several hundred pads soldered this way so far, I've had no bridging and only one cold joint that I had to fix (probably a dirty pad on a chip). Professional equipment (paste solder, stencils, profiled ovens) would make this easier, but I don't do near enough to justify the cost of all that.

Ciao,
Lenny

[Burgerman]

Once all the parts are positioned, I transfer the board to an ordinary toaster oven (the absolute cheapest that I could find at amazon.it - NOT TO BE USED FOR FOOD!).

Unless you like chips?

[ex-Gooserider]

The concern is that the lead and flux vapors from the melting solder will condense on the inside of the oven, and then potentially transfer to any food cooked in it afterwards - potential toxins hazard, plus the rosin flux tastes nasty. (I'm told)

At the Asylum it is noticeable that every toaster oven in the place is labelled as being for food or not... (Ditto any dishes that are for non-food, and it is a very serious violation of the safety rules to use an Asylum dish for non-food - we also prohibit washing anything used for toxics in the dish-sink...

The technique that our fine pitch SMD guy uses on resistors and other exposed lead components is to put a little dot of solder on ONE pad of each location where a given part will go (i.e. all the 1K resistors) He then uses a pair of tweezers and a fine tip iron to solder one end of each part to it's pad. After he gets all the parts tacked that way, he goes back and solders all the free ends... He does the same single pad approach with IC's with exposed leads. For BGA's and other hidden lead parts, he either uses paste, or puts solder on and then puts the board on a hot plate...

ex-Gooserider

[Astgabel]

Hello,

question, would the following bit sufficient for doing the crimping?

Cause I've already got the respective pliers, and this would be the most cost efficient way for me, also it's very high quality.

[Burgerman]

Probably. Soldering is cheaper and you can see it wont fall off!

[inglegrump]

I know these days we're supposed to use lead free solder....don't. Lead free solder is sort of OK for industrial electronics flow solder use where the temperature is controlled precisely (much hotter than lead + tin) but in normal use it can be hopeless. It makes a brittle joint. just solder a wire to something and move it and chances are you'll just snap it off. There is a reason why three of the industries that are 'excused' using lead free solder, Military, Aerospace and Medical Equipment, it's unreliable, and for something bumping down the road, not a good idea. Failure of vehicle ECU's has increased and you have to buy a new one, nobody is going to mend it to component level. Invariably the fault can be down to 1 PCB joint. You can still buy Tin/lead solder, do so please.

[garriew]

Does this look like a good deal?

http://www.tmart.com/YQK-70-Domestic-Us ... KQQAvD_BwE

[Burgerman]

Very similar to what I am using. But its dies are different, and less in number. As long as it does common sizes no problem. They are heavy, and can crimp serious stuff.

[ex-Gooserider]

Looks about the same as the one I bought from Harbor Fright, and a much better price... As BM said, if the dies cover the sizes you need (looks like they do) it should do the job... If I didn't already own the HF unit, I'd certainly be tempted by this one...

ex-Gooserider

Does this look like a good deal?

http://www.tmart.com/YQK-70-Domestic-Us ... KQQAvD_BwE