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How to protect poor solder joints

by jehan60188
Tags: joints, poor, protect, solder
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jehan60188
#1
Feb24-12, 09:53 PM
P: 204
I have tried and tried to make a decent joint, but the wire keeps falling off!
the joint is very small, and my tools are limited, so I need suggestions on rigging it up somehow.
I'm thinking a drop of two-part epoxy?

thanks!

picture: http://desmond.imageshack.us/Himg855...jpg&res=medium
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yungman
#2
Feb24-12, 10:20 PM
P: 3,904
You have to spend the money to buy a better solder station for the job. There is no way to protect the joint. You can paint over, glue etc, but you cannot make an intermittent solder joint reliable until you do touch up with new solder.....with a good soldering equipment. This is such an important thing. If you are too cheap, find a friend that has the station and use it if it is a one time thing. Buy a new solder station and a new tip, solder and return the station and keep the tip!!!!
jehan60188
#3
Feb24-12, 10:20 PM
P: 204
what should i look for in a good soldering station?

turbo
#4
Feb24-12, 10:56 PM
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How to protect poor solder joints

Quote Quote by jehan60188 View Post
what should i look for in a good soldering station?
Buy a decent Weller station (home-use, instead of industrial) that has heat-control. Use heats that are applicable to the job at hand. Most home-owners can use Wellers with light tips that heat up quickly. If you need to solder heavier stuff, you need to buy heavier tips for the soldering-guns and allow a bit more time for things to come to temperature.
Carl Pugh
#5
Feb24-12, 11:19 PM
P: 384
You are doing something wrong. The wire should not drop off.
What are you soldering? Aluminum and stainless steel won't solder.
Is everything very clean? Have you removed any burned flux?
Have you removed any oxide on parts you are trying to solder?
Are you using a solder that contains a large percentage of lead? The new lead free solder doesn't solder very well.
Does your solder contain a flux?
Is your soldering iron hot enough? When solder melts it should run easily and have a shiny color?
If your soldering iron requires tip to be filed and tinned, have you filed and tinned the tip? Don't file and tin soldering iron tips that are plated.
Temperature controlled soldering irons are a pleasure to work with, and serious professionals should own one.
However good solder joints can be made with cheap soldering irons. Your problem is not your soldering iron.
Using epoxy to keep the joint together is a poor idea and should not be done.
vk6kro
#6
Feb24-12, 11:36 PM
Sci Advisor
P: 4,044
Quote Quote by jehan60188 View Post
I have tried and tried to make a decent joint, but the wire keeps falling off!
the joint is very small, and my tools are limited, so I need suggestions on rigging it up somehow.
I'm thinking a drop of two-part epoxy?

thanks!

picture: http://desmond.imageshack.us/Himg855...jpg&res=medium
You need the joint to be mechanically stable before you try to solder it. If you don't do this, the wires will eventually pull the joint apart and possibly damage the printed circuit board.

I use hot glue to anchor the wires to something solid a short distance from the soldering. This sets quickly and can be removed easily if you need to. Hot glue sticks very well to PVC
You can also use cable ties to restrict the cable movement.
Averagesupernova
#7
Feb25-12, 09:55 AM
P: 2,535
Considering that the OP was considering gluing a joint that is supposed to be soldered I suspect that they are very inexperienced and doing something wrong which could include poor soldering equipment but not necessarily. So to suggest going out and purchasing new equipment is a bit premature. Lets find out a bit more first. I'm a bit surprised at some of the responses in this thread.
jehan60188
#8
Feb25-12, 11:12 AM
P: 204
I am pretty inexperienced- I've put together a mintyboost, as well as a 9V guitar amp, but that was easy since it was designed to be soldered by hand
also, I wasn't going to glue the joint, I am definitely going to solder it, but every time I try, it's brittle, so in order to avoid moving the joint around after soldering, I want to encase it in epoxy

the way I soldered this was to clean my hot iron with a wet towel, over-tin (a technical term i made up just now) the tip, use that to tin the wire, put the wire on the joint, and heat it until the solder from the wire ran onto the board.
i removed the iron, and held the wire for a few seconds to let the joint cool

any tips for improving my methodology?

wire selection? nothing too heavy, i imagine. stranded or single core?

as far as mechanical stability goes, I used bone-on-bone to stabilize my hand, which held a pair of pliers, which held the wire. is that what you are referring to?

thanks again, the more input i get the better
vk6kro
#9
Feb25-12, 07:38 PM
Sci Advisor
P: 4,044
as far as mechanical stability goes, I used bone-on-bone to stabilize my hand, which held a pair of pliers, which held the wire. is that what you are referring to?


No, if the wires are not pulling on your soldered joint while you are trying to solder it, then there should never be a problem with the joint falling apart while you are trying to solder it.

So, the idea is to make the joint stay in position even without the solder.

You can do this by gluing the insulation of the wires to something solid nearby, or you can add soldering pins to the holes in the printed circuit board. Then you twist the wires around these pins before you solder the joint.

Making the joint stable is not just a soldering convenience. It should be stable anyway, so that movement does not make the joint fail later.
In particular, there should never be anything soldered directly to the tracks of a printed circuit board that is not anchored. These tracks are only glued on and can easily be pulled away by movement.

Soldering pins can be obtained from data connecting strips like this one:
http://www.altronics.com.au/index.as...=item&id=P5430
NascentOxygen
#10
Feb26-12, 12:03 AM
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Quote Quote by jehan60188 View Post
any tips for improving my methodology?
I can give plenty. But first I need to know what it is that you are repairing--what you are trying to solder to what?

Can you post a close-up photo of the component and the site?
turbo
#11
Feb26-12, 01:53 AM
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The OP has posted an image that shows some fairly heavy leads being soldered to what should be surface-mount connections on a PCB. That is a recipe for failure, IMO, but then again I am used to soldering joints on guitar amps that need to be quite robust in order to survive. I would never try to solder heavy leads to surface PCB connections via globs of solder. If it is possible to install a couple of turret connections to that PCB without wrecking it, there would be a good chance of establishing decent connections.
jehan60188
#12
Feb26-12, 11:11 AM
P: 204
so, i need lighter wires, plus more stability in holding the wire still?
turbo
#13
Feb26-12, 11:25 AM
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Quote Quote by jehan60188 View Post
so, i need lighter wires, plus more stability in holding the wire still?
I would suggest lighter leads. Clean those contact points (gentle heat to avoid damaging the board) and remove the excess solder with a solder-sucker. Then clean the contacts with paste flux, tin them lightly and solder the lighter wires in place. I hate working on PCBs because they are delicate and the traces can be damaged easily.
jim hardy
#14
Feb26-12, 11:38 AM
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If he'll mechanically secure those wires so they want to lay right on the pads where he wants them soldered he can make it work. I'd drill a hole nearby and use cable ties.

All this has been said before - here it is in one place , no offense intended to anybody:

Three rules of soldering:

1. Cleanliness - you should see bright copper or bright solder
2. Make the joint heat the solder not other way around
3. Dont rely on solder for mechanical connection.

A little flux will help the solder flow. You want "Rosin Core" solder which has flux in the middle. NEVER use acid core on electrical stuff, that's for plumbing.

When soldering two wires together,

1. clean them
2. twist them together, or provide something to hold them together
3. Heat them with iron on one side, touch solder to other side of joint . Solder will flow toward the source of heat. When it flows, remove heat and dont let wires move until well after solder freezes.

When soldering wire to a PC pad:
1. Get the wire held where you want it by some mechanical means - nylon cable tie, string, hotglue, wedge it under a nearby part...
2. Clean and tin wire if not already so
3. Apply heat to pad and wire simultaneously, when solder on pad melts push wire into molten solder and remove heat.

i think your biggest trouble is not making the work heat your solder.
Use SMALL solder - my favorite is Kester 44 , 0.031 dia.
http://www.kester.com/SideMenu/Produ...9/Default.aspx

there's a product called Solder-Wick or Chem Wick that's handy for removing solder from circuit pads, see this video
http://www.ehow.com/video_4435740_us...ve-solder.html

and if you figure out how to block those %*U^$@#$ pop-up ads please let me know.
jehan60188
#15
Feb26-12, 12:01 PM
P: 204
Quote Quote by jim hardy View Post

and if you figure out how to block those %*U^$@#$ pop-up ads please let me know.
firefox + noscript
0xDEADBEEF
#16
Feb28-12, 03:25 PM
P: 825
I would second the recommendation about thinner wires maybe even some inner strands of a litz wire, you can solder these to a thicker one after a few centimeters, but the soldering pads tend to rip off if the wire can put any mechanical force on them. It would be best to fix the big wires mechanically to something (maybe with hot glue) so they don't rip off.

About the soldering rules that always get passed around I agree with most except a few (sorry for being opinionated about this ):

1) I hate Weller. Their stuff looks super ugly, and I found it clunky. I don't understand why everyone loves them. Go ERSA!
2) I think more important than a soldering station with adjustable temperature is a soldering iron with a fine tip. I only really use the adjustable temperature for soldering terrible things like manganin wire.
3) Heating the solder through the metal that is being soldered is advice for soldering rain pipes. In electronics flux is everything. Always have a bit of solder on your tip that still produces fumes. If there are no more fumes strip it off on a wet sponge and apply some more.Touch your contacts and then directly touch the tip with your soldering wire. This will melt the flux inside and produces a nice flowing drop right away.
4) If you blow on a drop of solder you can make it harden very fast, this can be very useful for delicate flying wire stuff.
5) Soldering pumps are better than soldering wig. (Except maybe for smd...)
Mike_In_Plano
#17
Mar4-12, 05:43 PM
P: 560
I see your problem, and it's fairly common. The leads are heavy and will concentrate the bending moment on the joint.

It's time to upgrade the lab:
Purchase some Kynar or Tefzel insulated wire wrap wire. This is small and resists solder heat.
Likewise, some Kapton (polyimide) tape will be a great help holding things in place and providing strain relief.

As usual, you should keep a flux pen, some acid brushes, some 95% or better isopropyle alcohol, and some solder wick handy. Solder wick degrades quickly, so keep it bagged with a silica pouch when in storage and flux it a bit to improve its ability.

It's also handy to 5 minute, two part epoxy handy. But not JB weld for electrical work. Usually the clear kind that comes in separate squeeze tubes works best for me. You can tack wires with it or make dams using tape and use it to mold.

Best luck

Mike
MATLABdude
#18
Mar4-12, 08:09 PM
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Quote Quote by Mike_In_Plano View Post
It's also handy to 5 minute, two part epoxy handy. But not JB weld for electrical work. Usually the clear kind that comes in separate squeeze tubes works best for me. You can tack wires with it or make dams using tape and use it to mold.
I've used JB STIK (think a better, cheaper Mighty Putty that actually came before Mighty Putty, good for up to 260 C / 500 F continuous) to insulate and "robustify" some soldered connectors that were inside a heat lamp--structural and sets in about 20 minutes.


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