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

[Loedown]

Originally Posted by 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!

Irons filings, why would you do this???????

Dremel will blast little fragments of metal under and around all sorts of QFP

I would absolutely not recommend this method.

[pandy71]

Reading the thread and i see that Lead Free Solder is used - Amiga chips are not compliant with such solder - also such solder create worse than normal lead-tin solder joints - so if this is possible please avoid Lead Free solders - on other side Lead Free parts can be easily used with Amiga and they are even better from DIY point of view.

[Eamoe]

Do you mean that the alloy the chips legs are made of contains lead?

[rkauer]

Not the alloy (which is mostly copper), the thin overcoat is plater + lead.

[pandy71]

chip legs are usually made from steel (easy to check - use the magnet), sometimes from braas (higher quality components), almost all are tin plated - exception is gold which is used for high quality joints usually for very tight removable joints like extension cards (side info - gold plated pads, parts of joints etc shall not be covered be lead or tin - almost all solders destroy layer of gold also direct contact gold plated parts and tin-lead layer will destroy layer of gold - gold easily migrate to tin-lead and layer is destroyed)

small hint - for cleaning gold plated pads use piece of ordinary printing paper - just clean once or two surface - no special cleaning is needed - paper act as very fine and quite gentle polisher.

new type of solders (Lead Free or RoHS compliant) can't be mixed with old type of solders - all remains from old solder (non RoHS) need to be removed from pads, new types of RoHS solders are usually higher melting points - it means especially for unexperienced that more easily is overheat electronic components, also new solders are worse in terms long term quality of joints, with some time they can create so called "whiskers".

http://image.guim.co.uk/sys-images/T...ers460x276.jpg

http://www.reflowfusingco.com/images/tin-whisker.jpg

http://www.mwrf.com/Files/30/14863/Figure_08.jpg
Generally old type of lead are:
easier to solder (lower melting point, better joints)
less risky for less experienced (better to see that joint is made properly - old, good joints are shiny - new always looks like cold joints)

also my advise - use lowest possible diameter for solder - 0.6mm are OK for most of work

Old solders (non Lead free) are still used by military, medical, automotive and space equipment - everywhere where high quality of joints is key to safety old type is OK - RoHS solders are forced to use only for customer products. You must use RoHS solder only if You produce and sell customer products - for own hobby purposes You can still use old type of solders.

Also is nice to buy decent flux - even if spec for flux says that flux is no-clean type (ie all remains from flux are safe for circuit and PCB and cleaning is not required) i advise to clean area of soldering by isopropyl alcohol so called IPA.
http://www.cirris.com/testing/guidel...lean-flux.html

rule #3 is important - verify that no-clean flux can be cleaned after soldering or heating - some of them can't be easily removed and can create weird problems in future especially in circuits with x-MOS IC (even small leakage current can destroy circuit)

How to learn - it easy - grab old PC mobo - at first try to desolder elements, learn how work with desoldering pump, how work with soldering iron - especially is important how unsolder elements with large copper areas of ground.
Learn hot to remove pins from holes - most of holes are also vias - they connecting more than one layer - if joint is to cold then it is very easy to rip off vias from PCB and destroy connection with internal layers - so learn first...
My advise - is electronic element is broken and need to be replaced - do not unseolder them - just gently cut pins by fine side cutter - Xytronics have few nice cutters.

http://www.xytronictools.com/

Buy a bigger wattage soldering iron with decent temperature control - bigger iron allow to work with large copper areas - ground planes - small irons are very poor - IMO 40 -60W is very decent and with proper tip can be used for normal and SMD elements - small irons need to be hotter due of their low thermal capacity - there is higher risk that You can overheat smaller parts - 60W iron with proper temperature can heat pin and pad quickly so it allow to finish joint faster.

[Zetr0]

@pandy71

Some great info there!!, thats bound to help out a lot of members =D


One thing i noticed though - I have not known any CPU or IC's legs/pins to be made from steel - steel is a very very strong resistor and would inhibit most signals.

From what I know CPU/IC pins are an alloys of the following Cu,Ni, Sn and Pb (Copper, Nickle, Tin and Lead) some pins like CPU pins are gold plated to reduce noise at the contact with the pcb/socket and improve conductance - it also looks awesome with the regal purple of the PGA MC68060 =D

I believe that there are also some IC's that use a Zinc alloy with Tin (brass) but this is based with some other elements too, Cu and Pb probably but I cannot remember them - damn.. nogging fail!

Interestingly I believe that ST's (not atari) licensed 68000 clone used a Zinc alloy as such I found it quite suspetable to acid damage - the pins on one side fell off like paper... still.... it made for an awesome keychain!

[pandy71]

http://www.ngiworld.com/Technical/Ma...LeadFrames.htm
steel i mean alloy42 - steel conductance is quite ok especially that typical length is lower than 1 inch.
Gold plating is very nice solution if socket and pin are gold plated - with some time there diffusion and gold migrate or self solder to second gold layer - after 20 yrs it is very difficult to remove the card or chip from socket - it is almost like welded.
Maybe ST use high Zinc brass or similar weird alloy?

[Eamoe]

Very interesting indeed! Thanks. What do you guys call a "cold joint"?

[pandy71]

http://en.wikipedia.org/wiki/Solderi...dering_defects

[Eamoe]

OK thanks. Looks like there can be various causes for a cold joint situation to occur. I've personally noticed that it's somewhat difficult to heat the parts before the solder. The main reason is that the surface of contact between iron tip and component leg is very small. To increase the contact surface, I've found that melting a drop of solder on the iron tip and then using this drop to heat the component works good. Do you think it's a bad idea?

[kipper2k]

Originally Posted by Eamoe

OK thanks. Looks like there can be various causes for a cold joint situation to occur. I've personally noticed that it's somewhat difficult to heat the parts before the solder. The main reason is that the surface of contact between iron tip and component leg is very small. To increase the contact surface, I've found that melting a drop of solder on the iron tip and then using this drop to heat the component works good. Do you think it's a bad idea?

.


My take on correct soldering is try to always apply heat to the pad, then touch the solder to the pad, preventing overheating. For IC's there are a few ways you can do it.

Flood soldering for example, apply excess solder across all pins/pads (not for the faint of heart), and then use wick to remove the excess solder and bridges

The method i use for small SMD IC's is to flux the pads, run the iron over the pads and solder the pads with a light coat of solder, clean off the excess flux (leave a small film so the IC can stick to it making the lining up easier). Lay the IC in position and run the iron back and forth along the pad/leg tips while pressing down gently on the IC, use a magnifying glass to check the work and then clean up.

For PLCC sockets, i remove all solder, clean all the pads thoroughly, dry them, use my abrasive pencil very gently on the pads, clean again, flux lightly, lay on the chip/socket and solder a pin on opposite corners. once happy with position, you can use the flood option or the iron to pad method

[pandy71]

personally prefer to heat through solder - so pad, pin and tip are clean and ready to solder, i put solder wire to pin and pad then simply touch solder wire by tip - first solder is heated and melted, rosin is released, then after short time which is enough to make proper joint, tip is removed. I'm using this method from many years (over 25 i think) with various soldering irons types - repairing many devices, no problems at all - after cleaning PCB looks like original one.

Also i used method described by kipper2k - excessive amount of solder i remove by solder braid (i use quite frequently coax shield filled with resin - it is always available - original wick some times can run out during heavy work )

To cleaning old pads (highly oxidated) sometimes i use ordinary eraser(rubber) - eraser should smell like normal rubber (why this is important - many eraser are made from vinyl or other elastic materials - older types of erasers are made from ordinary rubber but they are filled also with small, fine glass powder - sometimes they can be seen as small shiny spots - mostly those types of eraser was used in the past in technical drawing especially on tracing paper)

[Eamoe]

Originally Posted by pandy71

older types of erasers are made from ordinary rubber but they are filled also with small, fine glass powder - sometimes they can be seen as small shiny spots - mostly those types of eraser was used in the past in technical drawing especially on tracing paper)

Hah, I see exactly which type of eraser you mean. Nice trick, will try this on the oxydized pads of the missing CIA chip of one of my A600 mobos.

[pandy71]

http://www.pelikan.com/pulse/Pulsar/...62387./erasers

only for example - lead pencils, rubber made - many similar, various manufacturers are present on the market, after using eraser, clean area with alcohol - remove all rubber deposits - soldering should be easy and You may expect high quality joints.

[Retrofan]

Hi:
I've received today a ceramic resonator to change one of the mb which I've discussed in other thread.
I'm going to make it tonight and wasn't thinking to ask, but fitzsteve told me (he had the same component broken) that after he changed it it seems it didn't keep right...
This is the photo I taked:
http://img821.imageshack.us/img821/2765/abcd0013br.jpg

Can you give me any advice before I'll make it wrong?
I was thinking to twist it's "legs", as I'm going to put the Fast Ata over it (that's how it got broken) and don't want it to be very tall.

[FOL]

Originally Posted by Retrofan

Hi:
I've received today a ceramic resonator to change one of the mb which I've discussed in other thread.
I'm going to make it tonight and wasn't thinking to ask, but fitzsteve told me (he had the same component broken) that after he changed it it seems it didn't keep right...
This is the photo I taked:
http://img821.imageshack.us/img821/2765/abcd0013br.jpg

Can you give me any advice before I'll make it wrong?
I was thinking to twist it's "legs", as I'm going to put the Fast Ata over it (that's how it got broken) and don't want it to be very tall.

Solder sucker the solder from bottom of board.
Should be easy enough as its a through hole component.

[Retrofan]

Do I add more lead to it first and some Flux?

[FOL]

Originally Posted by Retrofan

Do I add more lead to it first and some Flux?

If it doesnt melt. Then I would try alittle solder first to get it flowing.

[Retrofan]

It seemed easy, but once I was there... now I'm trying to desolder the Rf modulator and it seems to be more difficult. I've desoldered the 3 small pins it has at the lowest part, but the 3 big ones that hold the box seem to have a hard solder.
Are those bent or they go straight through the hole?
Any advice to take the Rf out?

EDIT:
Don't hurry to answer me: it's out. I've used the "don't tell anybody I've told you this" way: I introduced an screwdriver between the box and the board while aplying the solder on the other side. It went out smoothly and I left no marks at all with the screwdriver.

[Oli_HD]

the shield pins are connected to the ground plane on the printed circuit board (A big internal copper layer) so its not that its a harder solder its just the heat being sucked out the iron as it tries to heat up the copper ground layer. Turn the heat up as high as it will go for those bits!