On Tue, 24 Mar 2015 00:03:54 -0700 (PDT), you wrote: >Hi Harvery, > >700 dgree can melt lead-free solder *directly* very well -- that's how I >adhere a layer of solder to connector pins. Then I put connector on top of >P2 on the board and heat the pins for making the solder melt and connect >joint just like the video.
This is called (or was) "sweat soldering" it does work, but may not be the best at times. No problem though. >But the solder between pins and P2 won't melt What may be happening is that the solder on P2 is protected by a layer of something, either oxide, or solder mask, or the like. I'd take a small xacto knife or equivalent, and gently scratch one of the pads to clean the surface. You want to stay in the plating area (assuming that this is solder plated. Did you use flux? Liquid flux is generally very useful in this kind of situation. You should be able to melt the solder and let it flow onto the board land (the contact area), without a pin there. If the solder just beads up, then you're not getting any heat transfer to the pad, or the pad is protected. I've had badly oxidized pads not take solder, and some plating on boards will not accept solder (nickel, if I remember it). In that case, some very gentle abrasion of the plating may expose the copper. This is a crude solution, though. You could also try cleaning the pads with a pencil eraser. It's quite abrasive and should not be used for edge contacts (it will remove gold plating very easily). >and none of it will adhere to the P2 even I heated 4-6 seconds in 700 >degree. Note that I cleaned the solder iron with tip tinner and brass >sponge before this step. Generally, what you do is avoid the tip tinner unless you're losing the tinning on the tip (solder won't adhere to the tip itself). I normally don't use it or need it. Then you add solder, just a bit, to the tip, use the sponge to clean it (and any oxides) off, then solder. You can add a tiny bit of solder to the tip, which forms a tiny drop there, and when put to a joint, will help heat transfer. The steps are generally 1) clean the tip, 2) do the joint, 3) put the iron back (it doesn't need to be cleaned at this point, the excess solder actually tends to protect the tip). > >Another way is just like you said (hope my understanding is correct) to >heat some solder and let it flow to the pin and wet the joint. I tried. But >the solder flow won't adhere to the P2 but just accumulated on the pin till >bridge with adjacent pin. Then there's something there that the solder won't wet. There might be a coating over the connector. > >Do you have any comment on this situation? > Just did, it's an odd situation, since most of the boards are manufactured to enable you to solder to selected areas, and the pads for such a connector site would be ready to solder to. Mine's a circuitco board, so I can't help with trying. If you have some leaded solder, I'd try that. I'd also get a tube of flux, you want the Kester RMA flux, which would be available at places like Mouser or Digikey or Avnet (not sure about Jameco). This flux is quite helpful for doing surface mount soldering (I do that a lot...). Harvey >Thank you so much! > >On Monday, March 23, 2015 at 8:37:46 PM UTC-7, Harvey White wrote: >> >> On Mon, 23 Mar 2015 19:46:19 -0700 (PDT), you wrote: >> >> >Thank you Tom and Harvey! I'll try again with higher temperature (800 or >> >even more higher till it melts) as well as adopt Harvey's suggestions. >> >Result will be reported in this thread. >> >> Ah, no, more temperature is not always what's needed. >> >> Too cold and it never melts. Too hot and it damages the board and >> what you're soldering. For leaded solder, 600 degrees is fine for >> small sensitive parts, 700 degrees for standard parts, and you almost >> never need 800 degrees. >> >> Try a few joints with the solder and just solder a few pieces of wire >> together, say 22 gauge or so. That gives you the practice you may >> need for lead free solder (behaves differently). >> >> >> > >> >I used lead-free .022 in 700 degree. Temperature is one of a few factors >> I >> >haven't adjusted in those attempts for not damaging the board. >> > >> 800 degrees is a bit too hot. There's a bit of a touch to it, as to >> how to solder and how not to. You want the solder to "flow" and to >> "wet" the joint as if it were water. >> >> I'd see what the melting point of your particular lead free solder is, >> and then see what the recommended iron temperature is as well. >> >> Harvey >> >> >Also I've found CircuitCo version in Jameco Electronics. >> > >> >On Monday, March 23, 2015 at 5:25:56 PM UTC-7, Harvey White wrote: >> >> >> >> On Mon, 23 Mar 2015 16:56:58 -0700 (PDT), you wrote: >> >> >> >> > >> >> >> >> >> >> >> >> >> >> >> >> >> >> > >> >> >I just checked my settings. I have my iron set to 430C / 806 F and >> >> haven't >> >> >touched it since soldering that JTAG connector last week. Yeah. So >> very >> >> >hot. Don't leave it sit on the board at that temp. I figured a fast >> dab >> >> at >> >> >high temp is better than letting it sit at lower temp though. Maybe >> I'm >> >> >wrong. Like I said, I'm not a pro with the soldering, but it worked >> for >> >> me >> >> >on the first try. Before I got my nice soldering iron I had problems >> >> >getting connectors soldered onto another board because my iron wasn't >> >> >getting hot enough. I don't have that problem anymore. :-) >> >> > >> >> >My solder is Kester 44 Rosin Core Solder 60/40 .031. >> >> >> >> OK, several things here: >> >> >> >> 1) 63/37 is eutectic for solder, and has the lowest melting point. It >> >> goes from liquid to solid and does not have a plastic phase (good). >> >> >> >> 2) 700 degrees is normal, and 600 is used for sensitive devices. >> >> >> >> 3) the amount of power that your tip can deliver (not necessarily the >> >> temperature) determines the size of the joint you can heat and >> >> successfully solder >> >> >> >> 4) clean is the key, a freshly tinned tip (clean and can transfer heat >> >> well) is much better than an oxidized tip. >> >> >> >> 5) better to use a brass sponge than a wet one. Less thermal shock to >> >> the tip. >> >> >> >> Harvey >> >> >> >> > >> >> >Tom Olenik >> >> >> >> >> >> -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to beagleboard+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
