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help on a project for school

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jake0o0babs

New Member
well this isn't like a real big deal it's just kinda annoying

in my opto-electronics class i'm doing a project where i'm putting together this radio kit, it's pretty common you've probably seen it before

well the solder seems to not stick to the circuit board very well...i ran an eraser of the circuit board a few times before i started working on it because i heard that's supposed to help but still the solder doesn't wanna go onto the board

i thought maybe my soldering iron wasn't supplying enough heat so i turned it up a little & i thought maybe the solder that came with it wasn't the greatest (unfortunatly i'm not sure the exact type of the solder that came with the kit)

but can you think of anything else i might have missed? any help would be appreciated

thanks
 

Sceadwian

Banned
It's obviously not raw copper, there's something on it etch resist maybe? How are your circuit boards made?
 

Sceadwian

Banned
There could be a hundred different ways they made the board then. Don't lick your fingers =O Scuff the board down to copper with something to get to raw metal, then the solder will stick.
 

Hero999

Banned
Are you using lead free solder?

Some lead free solders aren't compatible with leaded solders?

If the board is tinned with lead and you're using lead free solder (or vice versa) it might not stick.

Of course this is assuming you've cleaned the board and removed any copper oxide or dirt.
 

jake0o0babs

New Member
the solder is lead free

i believe i cleaned the board of well enough but then i can't be sure

today when i worked on it my soldering iron wasn't melting the solder very well at all so tomorrow when i go into class i think i'm gonna try a different soldering iron & see if that helps at all



also just recently i changed the tip on my soldering iron from a flat tip to a real fine point tip
i'm not sure if that has anything to do with the heat transfer of the soldering iron but maybe you would know if it would effect it or not
 

Sceadwian

Banned
I like fine tips they work great but a blunter tip may get better contact, I tend to have to wet my soldering tip a lot with a quick blob of fresh solder to get good heat contact with my fine tip. Stupid question but is it rosin cored solder? Maybe there isn't enough flux in it? Could try a neutral paste flux or something more aggressive if you clean the joint afterwards. Also make sure you're heating the board up well, lead free solders tend to need a higher temperature, it may not be flowing right because the PCB trace isn't heating well.
 
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jake0o0babs

New Member
yea i like the fine point too because it's easyer to work with
it's no problem cause i just have to turn the soldering up a little bit i was just wondering if that would be normal for a fine point to heat not as well as like a flat tip 1

& i believe it is rosen core solder...the kit came with solder & it's real shiny like but the 1 day i used solder that is in our shop that i've always used & it seemed to work a little bit better so i could always just do that again

thanks a lot of the help tho
 

Sceadwian

Banned
The tips should heat up about the same, but the smaller surface area/volume of the tip will limit the heat transfer compared to the broader heavier tip, the extra mass acts as a mini heat reservoir. But it practicality it's not much of an issue unless you're doing really high temperature stuff. If you cut the solder with a pair of sharp scissors and look at it closely with a magnifying glass you should be able to see the rosin core. Wire cutters tend to crimp the end making it hard to see. Extra flux never hurts, though it can get a bit messy.
 

jake0o0babs

New Member
yea the soldering iron that i use has like 5 levels of eat & when i changed up to the fine tip i noticed that i had to use like 4 or 4 1/2 so it's not a big deal i was just making sure that was like normal & there wasn't a problem or anything

okay i'll check it out in shop today & try & figure it out...i know that the solder we have in their for class is so just using that is always a back up option
 

audioguru

Well-Known Member
Most Helpful Member
Use electronics solder with flux in it.
Don't use solder designed for plumbing.
 

Sceadwian

Banned
Nothing wrong with plumbing flux, it's acidic though so the joint needs to be washed. Never use it near an IC where it can whic under the chip or around the leads.
 
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