anyone here with smd soldering experience ?

[joeybham]

hi guys just wanted a bit of advice i got a curcuite board and the connector has broken off i have a new connector to solder on however just want to advize please best way to tackle it.

i have noticed the connector pads where the connector broke off have are a dirty grey in colour and from my experience dirty grey connection are very hard to resolder too.

also what would be the ideal temps to use on hot air & soldering station.

i have a hot air station as well as a temp controlled soldering station.

have flux paist also a rosin core flux pen & no clean flux pen.

heres a closeup of the dirty connections.

anyone please advize best way to tackle it or any other thing which i would need or would help in the resoldering of new connector as they are very small connections and you have to be very carefull to not lift the pads with too much heat.

thanks in advance.

hosting images

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[uclabachelor]

You don't need a hot air gun.

Get some isopropyl alcohol to clean up the board. Remove the old pins with a regular soldering iron.

When the old parts have been removed, use a solder wick to suck up the old solder so you have fresh, clean pads to work with.

Line up the new connector and solder one of the ground pads on the side. You may need to realign the connector as you solder that pad.

That first pad will serve as an anchor while you solder the other side. If everything looks good, solder the pins and only use minimal solder as required to make the connection. You don't want each pad to be "bubbly". And use flux. A lot of it.

After you're finished make sure you clean up the area well with isopropyl alcohol.

 

[joeybham]

You don't need a hot air gun.

Get some isopropyl alcohol to clean up the board. Remove the old pins with a regular soldering iron.

When the old parts have been removed, use a solder wick to suck up the old solder so you have fresh, clean pads to work with.

Line up the new connector and solder one of the ground pads on the side. You may need to realign the connector as you solder that pad.

That first pad will serve as an anchor while you solder the other side. If everything looks good, solder the pins and only use minimal solder as required to make the connection. You don't want each pad to be "bubbly". And use flux. A lot of it.

After you're finished make sure you clean up the area well with isopropyl alcohol.

thanks for the advice uclabachelor.

i think soldering by hand wont be possible as these pins are very very small i took the pictures with my macro lense so they look quite big.

 

[William Gaatjes]

thanks for the advice uclabachelor.

i think soldering by hand wont be possible as these pins are very very small i took the pictures with my macro lense so they look quite big.

If i am not mistaken, on the right of this picture, there a component in a SOT23 casing. Above R9002. i am guessing but most of the resistors seem to be 0402 (especially R9002).
That is indeed small. But the connector solderpads spacing is about a 0402 length size. Thus with a new fine tip for the solder iron it should be possible. I advise to use solderpaste in these cases instead of solder wire. I do it myself as well and it makes life easy because it is solder with very good flux inside it. Use good forced ventilation because it will damage the insides of your nose, sinuses and lungs... I think you get the picture.

Solderpaste example :

Good old fashion lead solder at farnell. I noticed that the price has doubled.
Very bad development, that is.
http://uk.farnell.com/edsyn/cr-88/solder-paste-lead-free-5ml-10g/dp/1521898?Ntt=1521898

 

[joeybham]

If i am not mistaken, on the right of this picture, there a component in a SOT23 casing. Above R9002. i am guessing but most of the resistors seem to be 0402 (especially R9002).
That is indeed small. But the connector solderpads spacing is about a 0402 length size. Thus with a new fine tip for the solder iron it should be possible. I advise to use solderpaste in these cases instead of solder wire. I do it myself as well and it makes life easy because it is solder with very good flux inside it. Use good forced ventilation because it will damage the insides of your nose, sinuses and lungs... I think you get the picture.

Solderpaste example :

Good old fashion lead solder at farnell. I noticed that the price has doubled.
Very bad development, that is.
http://uk.farnell.com/edsyn/cr-88/solder-paste-lead-free-5ml-10g/dp/1521898?Ntt=1521898

thanks william i have used flux paist with my hot air station but never got a good contact.

i do remember trying to solder a old broken connector quite a long time ago just by useing flux and a fine tip and small amount of solder on end of tip and i ended up bridging the pins and i could not remove the soldered bridge i even used a soldering wick.

however might be better idea by just useing the paist and no solder at all on iron.

heres the paist i have would this be ok to use. also what iron temp would you use?
http://forums.anandtech.com/[url=ht...7;20[url=http://www.postimage.org/]psd upload psd upload

 

[William Gaatjes]

thanks william i have used flux paist with my hot air station but never got a good contact.

i do remember trying to solder a old broken connector quite a long time ago just by useing flux and a fine tip and small amount of solder on end of tip and i ended up bridging the pins and i could not remove the soldered bridge i even used a soldering wick.

however might be better idea by just useing the paist and no solder at all on iron.

heres the paist i have would this be ok to use. also what iron temp would you use?
http://forums.anandtech.com/[url=ht...7;20[url=http://www.postimage.org/]psd upload psd upload

I think the problem is that you applied it to your solder iron first.

Explanation :
When a printed circuit board is filled with components, first a metal sheet of limited thickness with holes in it (solder paste mask) is placed over the pcb and then solder paste is applied. After that step, the components are added. Then the pcb is preheated and finally fully heated and cooled down again. This is because of the characteristics of the flux inside the solder paste and because one does not want to damage the components and printed circuit board because of temperature - expansion issues and temperature - shrinking issues.


My way of doing it ?
First follow the cleaning steps of uclabachelor.
Check your solder paste if it is still alright. There must be a date of usage.
The flux inside the solder paste deteriorates over time, so do not forget that.
I also do not use water and a sponge to clean my tip. I use metal curls to clean my solder tip. Improves soldering quite a lot in my experience, see pictures.

Solderpad is bigger then component pin.
What i always do is the following depending if i have enough space on the solderpads. If the solderpad is larger then the leg of the component, i fixate the component first by soldering 1 pin at the end gently and then i apply a small amount of solderpaste to each pin individually and solder it with a fine tip solder iron. Use a new tip if possible for better results.

Solderpad is smaller then component pin.
If the solder pads and the legs of the component are the same size, i apply solder paste first to each solder pad individually, then place the component then use a hot air gun. Gently heat up the board, give it a minute to heat up and do not just heat the component only. See the board, solder paste with flux and component as one when heating. Keep the hot air gun at a distance of at least 2 inches or more depending on the type of hot air gun you have.

Luke, use the flux Luke !


And use proper forced ventilation ! Do not inhale the fumes unless you want to lose braincells !

 

[William Gaatjes]

I should mention one thing. Solder paste and flux are two different subjects.

Solder paste is made up of little solder balls with a greasy form of flux.

There is also a flux type that looks like water. This is not what i mean.

 

[TecHNooB]

I think the problem is that you applied it to your solder iron first.

Explanation :
When a printed circuit board is filled with components, first a metal sheet of limited thickness with holes in it (solder paste mask) is placed over the pcb and then solder paste is applied. After that step, the components are added. Then the pcb is preheated and finally fully heated and cooled down again. This is because of the characteristics of the flux inside the solder paste and because one does not want to damage the components and printed circuit board because of temperature - expansion issues and temperature - shrinking issues.


My way of doing it ?
First follow the cleaning steps of uclabachelor.
Check your solder paste if it is still alright. There must be a date of usage.
The flux inside the solder paste deteriorates over time, so do not forget that.
I also do not use water and a sponge to clean my tip. I use metal curls to clean my solder tip. Improves soldering quite a lot in my experience, see pictures.

Solderpad is bigger then component pin.
What i always do is the following depending if i have enough space on the solderpads. If the solderpad is larger then the leg of the component, i fixate the component first by soldering 1 pin at the end gently and then i apply a small amount of solderpaste to each pin individually and solder it with a fine tip solder iron. Use a new tip if possible for better results.

Solderpad is smaller then component pin.
If the solder pads and the legs of the component are the same size, i apply solder paste first to each solder pad individually, then place the component then use a hot air gun. Gently heat up the board, give it a minute to heat up and do not just heat the component only. See the board, solder paste with flux and component as one when heating. Keep the hot air gun at a distance of at least 2 inches or more depending on the type of hot air gun you have.

Luke, use the flux Luke !


And use proper forced ventilation ! Do not inhale the fumes unless you want to loose braincells !

please don't inhale anymore fumes :|

 

[William Gaatjes]

please don't inhale anymore fumes :|

You are right. I will hide my failure by stating English is not my native tongue.

When it comes to type errors i am

of course...


Note to myself :

Lose vs Loose

A lot of people are mixing up lose and loose. In particular, a lot of people are writing loose when they really mean lose. Here are the definitions of the two words from my Penguin dictionary:

loose [lOOs] adj not fastened or pre-packed; not tied up or confined; able to move freely; not tight, not firmly fixed; not close-fitting; careless, inaccurate, vague; dissolute, immoral; not closely woven; flabby; (of bowels) inclined to diarrhoea; l. box stable or van in which an animal can move about; at a l. end uncertain what to do next; unoccupied ~ loose adv in a loose way; play fast and l. behave rashly or unscupulously ~ loose n release; on the l. free from restraint; on a spree; ~ loose v/t untie, undo; release from confinement or constraint, set free; detatch; fire (gun); shoot (arrow); (eccles) absolve.

lose (p/t and p/part lost) [lOOz] v/t and i no longer have; be deprived of by accident or misfortune; mislay, fail to find; fail to get or win; be too late for; be bereaved of; waste; be defeated or beaten; suffer loss, become worse off; fail to hear, see or understand; cause or allow to perish; (of clock or watch) go too slowly; (refl) miss the right path; become absorbed in; l. one's head become flustered, panic; l. one's temper grow angry; l. one's way fail to find the right path; l. out (US) be defeated after a struggle.

Examples:

This knot is too loose.
Please do not lose my book.
I had better not lose that file.

One way to remember the difference between the two words is to think that "lose has lost an 'o'".

Ross Williams (ross@ross.net)
24 January 2002

 

[joeybham]

thankyou for the kind advice.

that flux is have proper paist not water type.
heres the details.

amtech RMA-223-TPF Clean Flux for bga rework is a kind of leaded solder flux.

2. RMA-223-TPF Clean Flux is a homogeneous mixture of the highest quality pre-alloyed solder powders and mildly activated resin paste flux.



3. This RMA-223-TPF clean flux and leaded solder flux with a special blend of gelling additives in this formulation, it prevents segregation of solder cream and provides a creamy mixture ready for application.


could you suggest best temp to use on my soldering station. as dont want to lift any pads off the board by useing too much heat.

thanks

 

[William Gaatjes]

I always use around 315 to 330 degrees celcius.

This is the solder station i use.

I am not sure but i think i use this point.

You do not have to have the same material. It is just as a reference or example.

 

[mindless1]

It's not as hard as you're making it out to be! Put a fine tip on the iron and desolder all the pins one at a time. Scrub clean with alcohol/water solution and a stiff toothbrush. Put flux on the area then put the desoldering wick down on the first pin. Put a bevel tip in the iron, put it down on the wick and drag across the pads to get the solder off. It is important to get as much of the solder off as possible so they are all the same height.

Next lay down a SMALL bead of soldering paste across all pads. Don't bother trying to individually apply to each pad, the key thing is don't put down too much. Next either glue down the connector or tack it down by positioning while soldering one of the end pins.

Next drag your bevel tip across all the pins. You will not have bridging if you don't use too much solder paste. If a significant amount of solder starts to build up on the iron tip, stop and wipe that off. Better to have not enough paste and put down a 2nd bead to get it done, than to have too much paste and try to get rid of solder bridges.

Temperature? Doesn't matter all that much (some will disagree) so long as it's a few dozen degrees above the specific solder/paste melting point... you aren't holding the iron in one spot long enough for overheating to happen and the flux in the paste distributes heat to make pad damage unlikely. Using a drag technique I'd set the station for about 350C, or closer to 300C if you still feel the need to solder pins individually... there is a chart for melting points at the following wiki page,
http://en.wikipedia.org/wiki/Solder#Solder_alloys

 

[joeybham]

hi guys just a update to this thread.

i have managed to get the new connector on but im haveing problems soldering the little pins :'(

the legs on the new connector just wont solder to the curcuit pads i have managed to get 1 leg soldered but the other just wont make a good contact.

i cleaned the area free of old solder and wicked the old solder off the pads and cleaned with isopropyl alcohol.

then soldered the new connector into place by the 2 ground pads.

i just used amtech RMA-223-TPF Clean Flux paist .along the connector pins. useing a fine tip soldering iron set at 330 degrees and gently touched each pin.

after i went over them twice they still have not made a good contact.

i then tryed my hotair station.

again i used amtech RMA-223-TPF Clean Flux paist but no go.

and i also tryed a flux pen and heated the pins then i allowed it to cool but the connector pins are still not making a contact ??

im stumped why the new connector pins are not soldering to the curcuit pads as ive used amtech RMA-223-TPF Clean Flux paist also tryed a no clean flux pen and also rosin core flux pen.

the pins just wont stick or flow.

 

[PottedMeat]

you wicked the old solder off, did you add a little dab of solder until it flowed into the gap when you heated the contacts?

 

[Modelworks]

Are you mixing leaded and lead free products ?
Leaded solder products don't work too well with the lead free products. Sometimes using leaded solder with lead free soldered products results in solder joints that don't form well. Sometimes you have to increase the heat significantly to get a good bond. Make sure the flux you are using is compatible with the solder and the board. Some flux doesn't work well with lead free.

 

[mindless1]

^^ There should not be a gap, connector pin should sit on the pad, having squished out solder paste applied before the part was tacked down. If the pin is not sitting on the pad, it could help to use a probe (I used a set of picks that look like dental tools) to hold it down while soldering. It helps if the probe is a less reactive metal like stainless that is polished so it is less likely to become part of the solder joint... but not entirely necessary depending on the situation and space available.


Which is the solder not wetting properly? PCB or connector? Either there was excessive residue remaining on that part, or the two were not in contact so your iron is only heating up one of them, or your solder paste's flux is shot (old/dried out/etc). Also make sure your iron tip is clean and uniformly wet with solder.

I realize it is hard to get a good macro of this but a good picture focusing on a typical failed joint (need not try to show all of them in one picture) might help.

 

[PottedMeat]

^^ There should not be a gap, connector pin should sit on the pad, having squished out solder paste applied before the part was tacked down.

if i'm reading through OPs postings right - i don't think he's using any solder paste, just flux in paste form.



OP, you've removed the solder, you need to add solder, the flux is just there to help it adhere to the surfaces.

 

[mindless1]

if i'm reading through OPs postings right - i don't think he's using any solder paste, just flux in paste form.

OP, you've removed the solder, you need to add solder, the flux is just there to help it adhere to the surfaces.

heres the paist i have would this be ok to use. also what iron temp would you use?
http://forums.anandtech.com/[url=ht...rl] [url=http://www.postimage.org/]psd upload psd upload

Lead, tin, silver, bismuth, antimony, indium, copper...

http://www.amtechinc.com/pdf/REVISE_1.PDF

Is this what is being used? Should be easy to tell by color, if it's gray it has solder balls in it.

 

[joeybham]

http://www.amtechinc.com/pdf/REVISE_1.PDF

Is this what is being used? Should be easy to tell by color, if it's gray it has solder balls in it.

\


yes mate thats correct thats the flux im useing its a cream paist colour specs say its a solder paist so thought this should do it.

 

[Modelworks]

The pins you are attaching are not that small. Forget the paste. Get some small diameter solder and use some flux. I thought we were talking about really tiny stuff, I have done smd chips with 48 pins using solder so pins that large shouldn't be a problem.

 

[joeybham]

The pins you are attaching are not that small. Forget the paste. Get some small diameter solder and use some flux. I thought we were talking about really tiny stuff, I have done smd chips with 48 pins using solder so pins that large shouldn't be a problem.

hi mate i have tryed useing solder with a fine tip but keep bridging the pins. and i haveing to keep wicking it off

 

[joeybham]

out of interest im useing useing 60/40 22swg solder.


dont know whever to just buy this stuff http://nl.farnell.com/productimages/farnell/standard/152189807-40.jpg

however money waisted if its just the same as my paist flux.

 

[Modelworks]

hi mate i have tryed useing solder with a fine tip but keep bridging the pins. and i haveing to keep wicking it off

Solder and then use wick to clean it up. Done all the time with surface mount circuits. Some people even flood all the pins with a blob of solder then wick up the excess being careful not to remove all of the solder from the connection.

http://www.youtube.com/watch?v=wQXhny3R7lk

 

[A5]

Solder and then use wick to clean it up. Done all the time with surface mount circuits. Some people even flood all the pins with a blob of solder then wick up the excess being careful not to remove all of the solder from the connection.

http://www.youtube.com/watch?v=wQXhny3R7lk

This is what I would do as well. Generally the solder doesn't really want to stay on the non-pad portions of the PCB (the technical term escapes me at the moment) since it is not as hot as the actual solder pads (which makes sense since the pads are conductors and the plastic mesh of the board is an insulator).

 

[Howard]

This is what I would do as well. Generally the solder doesn't really want to stay on the non-pad portions of the PCB (the technical term escapes me at the moment) since it is not as hot as the actual solder pads (which makes sense since the pads are conductors and the plastic mesh of the board is an insulator).

solder mask

three things you need: small tip, small solder, big flux