PDB Soldering Help Please!!

[tombrown1]

Finally found some time to work on my new Y6. Soldering the thickest PDB I've ever had. I'm having a hell of a time just getting the ESCs on there. They just don't seem to be taking.

I'm using a Weller 100/140 watt gun with rosin core unleaded solder. Not using any flux - just trying to get a little pool of solder to stick to the PDB pad without even connecting the ESC, then melting the ESC wire into it. I got a few to stick, but it's taking forever and a couple that I had previously done have popped off.

The tip is clean on the gun, hex bolts are tight, the ESC wires are pre-tinned. After the solder slides or pops off a few times, it looks like the pdb pad gets a bit of a brown residue on it. So I scrape that off and start again.

Very frustrated right now and nervous that these suckers are going to pop off in mid-air.

I've watched many soldering videos online in the past, but they don't seem to be helping me in this situation.

Any help is much appreciated.

Thanks,

Tom

 

[SoCal Blur]

There may be a protective coating on the copper on the PDB. Take a little emery cloth and wipe it over the copper pads a few times. Also, if you're getting brown, burnt residue, it means your soldering iron is too hot...you're burning the rosin and that's not good. By the way, rosin core is essentially the flux. Unleaded solder is a pain, and in the end is not as strong as leaded solder - just as an FYI.

 

[RTRyder]

The problem is the unleaded solder. The heating characteristics of leadless is different than good old 60/40, I have a heck of a time getting the unleaded stuff to melt with a normal iron when I try to change wires on factory ESCs made with the stuff. Once I do get it off I put the wires back with my favorite 60/40 tin/lead rosin core, much easier to work with. I'm not particularly worried about exposure to lead, heck I used to wash engine parts bare handed in leaded gasoline back in the day, guess that explains a lot as my wife would say .

Bottom line is the lead free solders require on the average anywhere from 20 to 45 degrees C higher iron temps to melt and in some cases the higher temps can be damaging to components if you're doing board repair. You'll also find the iron goes through tips much quicker with the lead free as the necessarily higher temps cause them to oxidize and erode a lot faster than lower temp 60/40. I seem to recall seeing lead free specific soldering irons/tips for sale in supply house catalogs but can't put my hand on one at the moment.

Ken

 

[SoCal Blur]

There seems to be a fine line between the correct temp for lead-free solder and burning the rosin. In my limited experience with lead-free solder, it doesn't seem as strong as the 60/40. I fear the day (which is coming soon if it's not hear already) that aircraft avionics is soldered with lead-free solder.

 

[tombrown1]

Thanks guys! I'll try some leaded.

 

[PeteDee]

380 degrees for lead type, more like about 420 degrees for silver type.

I do like the silver type but some small connectors and boards do not like the extra heat.