Soldering hints

[Shadowfire]

Right. Typically you will heat up the surface mount component with hot air, remove it when the solder melts, let the board cool down, use a normal iron + braid to remove the old solder, clean the board, lay down new paste, align/press the new part down, use the hot air to melt the solder.

When the new component is soldered, you gently press on the pins laterally with a pick or some other probe and see if the pins move. If they do, you need to touch up the joint with more solder.

Finally, you will visually check for shorts, and clean them up (using braid if there's an excess of solder, otherwise you would irrigate the area with flux, and repeatedly heat up the pin and clean your tip). You want good (8x) magnification, and don't forget to check up inside the area behind the pins for shorts - if you get a short there and you can't clean it up with the iron and flux, your only option is to load it up with a lot of solder, then use braid to draw the excess out.

Last, but certainly not least, CLEAN THE FLUX OFF THE BOARD.

[CU_AMiGA]

hi

i am looking into getting some soldering practice.i was talking to alexh and he recommened looking on maplin website and see wot they had. here is wot i found:

http://www.maplin.co.uk/Module.aspx?ModuleNo=98133
http://www.maplin.co.uk/Module.aspx?ModuleNo=218050
http://www.maplin.co.uk/Module.aspx?ModuleNo=4103
http://www.maplin.co.uk/Module.aspx?ModuleNo=10271

here is the search list:

http://www.maplin.co.uk/Search.aspx?...lder&source=15

am i on the right track here guys? have i found anything good or is there anything else anyone here recommends? thanks for your time.

regards

[Dimlow]

I have the first one in the list, it works well, was cheap when i got it a few years ago, it has nice tips.

[Washac]

Hi All


Been out of touch with this pastime for a while and need some advice.

I am going to buy the Iron suggested in this thread from Maplin & pack of different tips.

Just one quick question, which gauge solders would be best for any soldering job
within an Amiga.

I used to use two years ago but have no idea what they where.


Thanks for reading....

[CU_AMiGA]

right guys. now got myself most of the equipment. does anyone know where i can get thin lead solder thats suitable for fine soldering? maplin only sells lead free!

[Zetr0]

for those looking for a good solder -

1.5oz 0.022 Silver Bearing Solder from Radio Shack £2.50 + £1.79 pnp



I use a combination of the above (for through hole) and the same stuff (but different pitch) 0.015 for SMD work

[Washac]

Originally Posted by Zetr0

for those looking for a good solder -

1.5oz 0.022 Silver Bearing Solder from Radio Shack £2.50 + £1.79 pnp



I use a combination of the above (for through hole) and the same stuff (but different pitch) 0.015 for SMD work

Hi


Thanks for the pointer

[Peter]

See this image... well, on the left hand side for example where it states "connect this together"... there are two soldered points yes... what do you do to connect them... do you just put a blob of solder on one point and then using your hot iron drag the molten solder either up or down so as it meets the other point and connects the two, leaving a line of solder between the two points when it gets cold?

Not a very technical description I know but is what I am stating essentially correct?

See picture...

[xc8]

put a small piece of cable + flux (between the 2 points), to make a 'bridge'

Chris

[Hewitson]

Wtf for? Simply bridge it with solder.

Peter: Melt both solder points simultaneously and stick a bit of solder in between them. Remember the solder goes on the component you are soldering, NOT the iron.

[Eamoe]

Erm, soldering ultranoob questions:

1. Is it possible to solder surface mount chips and caps with "iron + solder" rather than "hot air + solder paste"?

2. What exactly is flux and when do you use it?

[Merlin]

@ Eamoe

Look up "drag soldering" on Youtube and you will see someone soldering surface mount chips with a normal iron.

Flux is a compound that cleans the component to be soldered and it makes the solder 'take' to the component and wet out much better. You normally have to clean this off afterwards, although there are 'no-clean' fluxes available.

[Eamoe]

@Merlin

WOW... boy am I noob! Incredible vids I've seen here. Now I do understand how soldering such small parts can be made possible. If I get this right, the flux is essential: it makes the solder "stick" to other metal parts, like pads and chip legs, correct?

[Zetr0]

Hiyas Eamoe

Originally Posted by Eamoe

Erm, soldering ultranoob questions:

1. Is it possible to solder surface mount chips and caps with "iron + solder" rather than "hot air + solder paste"?

Yep, I do it all the time, just takes a little more patience and soft calming music, like Enya or Enigma or if you want a little progressivenes, perhaps I could suggest some Annhilator: Alice in Chains.

Originally Posted by Eamoe

2. What exactly is flux and when do you use it?

Flux is a liquid that is use to spread the heat of the iron / gun and clean the contacts from oxides that build up from contact with the air thus making it hard for solder to bond with the contacts.

Flux is slightly corrosive and some are damn right corrosive, however some are NON-Clean - meaning they clean themselfs and add a protective barrier once the solder has cooled.

Flux comes in liquids and Pastes, some types of flux contain micro-solder beads, meaning once applied and heated it does it all in one go, this is called Solder Paste and has several compositions for different applications.

for now I would suggest the following

1. When to use Flux?

Always

2. What Flux do I use?

well this really is dependent on the project, but a quick guide would be at what temperature will you be soldering at?

If its above 280c then most liquid Flux's will vaporise before doing their job, so above 280c then a Paste Base Flux is recommended.


To give you an idea.

When soldering SMD (surface mount) I usually run about 220 - 260c and use a liquid flux (Laco Liquid Flux). However when I am reworking heavy gauge components like Power Supplies I use a Flux Paste - infact I am a little naughty as I use Copperlux Flux Paste.

CopperLux Flux Paste is intended by design for brazing copper pipes and not for electronics.

This is because its highly corrosive and if left even for a day it will eat copper tracks right off the PCB. to stop this one must clean the PCB very thorougly.

Knowing your tools well is an advantage!

As with all Flux, even those that say NO CLEAN, I always clean them, to clean I would recomend IPA (thats iisopropyl alcohol) it lifts, cleans all dirts and greases as well as neuralize acids.

However this can be a little expensive, So I use pre-diluted Car Screen Wash.... which is diluted IPA..... I can get about 5 Liters of this to half a liter of IPA, sure you can use a bit more, but then you have alteast 5 times as much.

To help clean I also use an electric toothbrush and a Ultra Sonic Cleaner

[Eamoe]

Why, thank you Merlin, and Zetr0 for the nice and interesting post, that sets me pretty good to start some serious soldering. Still missing flux, IPA and nail polish to complete the equipment.

Very interesting way to go, the car screen wash! Doesn't the "Fresh Citrus Fragrance" from that mix pose problems when the rest evaporates? I thought they also put a tiny bit of soap in these.

My absolute goal for now is to manage to solder an U7 (CIA) chip on an A600 mobo. That's surface mount and it looks quite reduced in size... compared to what I've soldered till now!

[Loedown]

Originally Posted by Eamoe

Why, thank you Merlin, and Zetr0 for the nice and interesting post, that sets me pretty good to start some serious soldering. Still missing flux, IPA and nail polish to complete the equipment.

Very interesting way to go, the car screen wash! Doesn't the "Fresh Citrus Fragrance" from that mix pose problems when the rest evaporates? I thought they also put a tiny bit of soap in these.

My absolute goal for now is to manage to solder an U7 (CIA) chip on an A600 mobo. That's surface mount and it looks quite reduced in size... compared to what I've soldered till now!

A600 CIA is J-leg SMD, take the old one off with a heatgun, or if you're sure it's phuckt you can cut the tops of the legs where they come out of the chip, be careful with this method, it can place stress on the solder pads. Once all the pins are cut, simply take tweezers and remove them one by one, making sure you let the solder melt first, they don't need much pressure to be applied to remove them. Clean up the pads with soderwick ( solder wick ) in a pattern, always rub *very* gently in the direction of the pad in a 'z' like fashion, so top left to right, then next down left to right. until all solder is removed from every pad, do not stay on one pad too long as you can lift it. At this point clean all the old flux off the board, using Contact Cleaner / Fluxclene / Isopropyl and let it dry. Apply new flux, place the chip down and solder two diametrically opposed corners, making sure that it's lined up in X-Y directions. Then work your way along with a fine tipped iron, a pin at a time, wiping the tip after about every 3rd pin or so, I'd also recommend using fine solder and applying the iron tip to a 45 degree front / side, making sure you don't let the tip contact two pins at once. Do the first side, then the opposed side, repeat for the second set. Apply another layer of flux, a very light one and then *carefully* drag the iron tip slowly down a side, making sure it melts every pin's solder again, also making sure it doesn't short pins or leaving a blob of solder. This last step isn't crucial but provides a much nicer finish. Clean up excess flux and enjoy your new chip.

I'd practise first on another chip, get and old PC mainboard and do a few J-leg parts on that. If you'd like me to post a Youtube video of such, I can, just not today, probably mid to late week coming.

I may even consider doing a small series of videos for J-leg, gull wing and fine pitch, if people are interested?

[Jope]

J-leg? Is that an official term? I always called them PLCC.

[Loedown]

Originally Posted by Jope

J-leg? Is that an official term? I always called them PLCC.

PLCC is the package style and the pins are referred to as J-leg AFAIK

http://workmanship.nasa.gov/lib/insp...0Packages.html

http://en.wikipedia.org/wiki/Plastic...d_chip_carrier

J Lead is mentioned, but I've also heard J Leg and that's what I use.

[Eamoe]

Originally Posted by Loedown

I'd practise first on another chip, get and old PC mainboard and do a few J-leg parts on that. If you'd like me to post a Youtube video of such, I can, just not today, probably mid to late week coming.

I may even consider doing a small series of videos for J-leg, gull wing and fine pitch, if people are interested?

Yeah!


Please do post videos when you can, I am interested.

Thanks for the technique. I will try on other PCB's, have a few here that take dust. My sodler iron has a "pointy" tip, not these 45 degrees beveled ones you see in videos like this (@1:00): [ Show youtube player ]. Would that totally prevent me from managing a nice solder?

[rkauer]

If you have a steady hand, a Dremmel cutting tool will ease the removal of the dead chip: use it on the top of the leads/legs so you can pull the chip out and then start to unsolder the remaining pins as Loedown told you.

Remember to wash the entire board, Dremmel use to spread metallic powder all over the place!