Need advice about soldering FC

R

Rex3906

Member
So ive soldered a few pads on a f4 05 aio and theres flux around the outside and i want to clean it so it doesnt bridge or short anything but afraid to to use some kind of cleaner like rubbing alcohol, dont know if it will hurt anything on the board? Also is it ok to use the rubbing alcohol or should i buy actual flux cleaner? Oh and im using good 60 40 solder with %2.2 flux n says ra flux on it, hope these arent dumb questions n thats why i havent been able to jus google this
 
Rex3906 said:
So ive soldered a few pads on a f4 05 aio and theres flux around the outside and i want to clean it so it doesnt bridge or short anything but afraid to to use some kind of cleaner like rubbing alcohol, dont know if it will hurt anything on the board? Also is it ok to use the rubbing alcohol or should i buy actual flux cleaner? Oh and im using good 60 40 solder with %2.2 flux n says ra flux on it, hope these arent dumb questions n thats why i havent been able to jus google this
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Use 63/37 solder. It has a lower melting point and gives you some room for error. Bit more money. but worth it. Amazon has tons of it.
 
You should use RMA flux.

With type RMA flux, the flux residue after soldering is non-corrosive and non-conductive. Kester 186 rosin flux has been developed for use in critical applications where difficult assemblies are to be soldered.
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Jackson said:
You should use RMA flux.
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RMA flux should leave behind less residue and still be non-corrosive.

I use some R for the low impedance characteristics and a good bit of RA but it is pretty messy.

There are desirable and required characteristics for your solder, RA would only give you some desired properties so here is no real reason to buy something else if that is what you already have though.
 
Thankz alot for all your advice, i desoldered the small solder pads to clean the flux off but i cant get all the stickyness off so is that ok is it conductive at all? I dont know alot about soldering i know how to thats easy for me but the pads being so close to each other. I tried to scratch some of it off went through paint real small not touching any pad itz right in the middle. Im gonna cover it with epoxy so thats y i need to know how conductive the flux is?
 
I resoldered n im not using the small ground on top, gonna put vtx n cam ground on the bottom small pad n its not alot of flux on it after cleaning but is still there. Couldnt use a better pic of it cuz of the size
 

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Ya im a very detailed person i make custom exotic wood furniture builder where little detailz matter jus getting into electronics. Thnx i figured so but wasn't sure lol
 
Thought its stronger then paint to go over where i scratched the board through the black paint n looked like copper. I dont know much about electronics n the pads r so close n that scratch is in between a 5v n ground n know that if they touch itll cauze a short
 
Its obvious that with the advice from some questions ive asked around on forums that fc boards n other pcb boards that there alot more forgiving than i thought
 
I'd suggest a little bit of fingernail polish, you probably just scratched the solder mask off. As long as you are on standoffs you should be good. The flight controller shouldn't be against he frame anyways.
 
Rex3906 said:
I resoldered n im not using the small ground on top, gonna put vtx n cam ground on the bottom small pad n its not alot of flux on it after cleaning but is still there. Couldnt use a better pic of it cuz of the size
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Rule number one was always make a good physical connection. Not always possible anymore.
Rule number two was if your solder joints are shiny. They are probably good.
Yours loook Shiny!

Have fun
Bill
 
... Not too bad of a soldering job for a newb at it ... lol ... that should work just fine. :p

Words of advise on future soldering work though:
Solder is NOT melted upon the wire or the pad as was obviously the case by looking at two of your solder pads.

The tip of the soldering iron should contact the place where the wire meets the pad in such a way that BOTH the solder pad AND the wire are heated simultaneously
to the point at which they melt the solder when it's touched to THEM (not to the tip of the iron). The solder will then flow over the entire pad uniformly and create a "fillet"
which rises from the edges of the pad up to and around the wire. :)

If the pad is not hot enough it will look like "a drop" of solder sitting atop the pad (like your "S4 pos and neg" connections) but all the other connections look really good.
In fact, the connections I'm critical of are good enough too, so I wouldn't mess with them again. If the pad is hot enough but the wire is not, then the pad will be covered
well but the solder will "pucker" around the wire rather than flowing up onto it. The connection being "shiny" is proof that the solder was clean (no contaminants or slag)
and that the solder was not overheated. ;)
 
Ya when im soldering the wire to the pad im gonna make sure its melted n on whole pad. I cant change temp on soldering iron n its 400f it doesnt like alot of solder one pad had too much n wont melt n now i gotta desolder n redo.

And i got another question my vtx that i got from another quad is 5v i cant find docs on it, can i put the cam 5v n vtx 5v on same pad?
 
Rex3906 said:
can i put the cam 5v n vtx 5v on same pad?
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Usually yes, but you want to check that the PDB you're using can handle it before trying.
The total current drawn by the cam and the VTX added together should be less than the rating
for that connection on the PDB, otherwise you'll fry the voltage regulator on the PDB. ;)
 
Rex3906 said:
I cant change temp on soldering iron n its 400f it doesnt like alot of solder
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That's pretty low temp for an iron unless it's used for soldering the actual parts (tiny parts) onto circuit boards.
Do yourself a favor and buy an iron that's at least 600-700 degrees because soldering is best done quickly , otherwise you risk having the pads
lifting off of the board from being too hot for too long (not hot enough to melt the solder but still hot enough to delaminate from the board).
 
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