Soldering tips

Viserion · 16 July 2013, 20:30

As I have very little soldering experience, I thought to improve my skills before trying on my trusted A500, that I bought back in the day.

I have an AB IP9000HD that don't work any more, and after opening it I could see that some of the capacitors looked very dodgy.

So this would be the perfect way to recap this motherboard to gain some skills, as I don't care if this works or not as I consider it a write off anyway.

I got what I needed of parts, and started to remove the original caps by heating up the solder to remove it(the bottom side of the MB).

This is where I hit the first wall

No matter how high I sat the temperature it didn't melt.

The iron I use is a Weller WECP-20(heat regulated), and while it's old, I have had no problem melting solder on other projects I've had, so I don't think that is the problem.

I then tried to remove them from the top, and after using an air gun and moved the caps front to back, left to right a lot, I got one off.

This is when I got my second suprise

The minus side of the caps is round and has a goldish colour, and the plus side is square.

The distance between them is so small that it's impossible, or perhaps very difficult of for one who is more skilled than me, to use ceramic capacitors, as the capacitors covers more or less the whole distance on the outer side of both plus and minus.

I have tried electrolyte capacitors as well, and sort of get them on the MB, but I need to cut the connectors as I can't get them trough the MB, and they do not sit well.

I did clean the connectors before I tried to solder on them.

Any ideas of what is going on, or should I just bin hte MB, and try to find something else.

prowler · 16 July 2013, 21:16

Thread moved to the support.Hardware forum.

bubbob42 · 16 July 2013, 21:41

When removing components, fresh solder will be extremely helpful. I had similiar problems when I started recapping. Apply fresh solder to the joints first, then heat them up and the components will come off easily.

To free holes in the PCB I recommend using a bit of fresh solder and a wooden toothpick: Apply solder, heat it with a thin tip and then jam the toothpick in while the solder is still fluid.

Needs a bit of practice.

demolition · 16 July 2013, 22:18

There can be several reasons for the solder not melting. If the caps have been leaking, the outer part of the solder will have reacted with the acid, and that part won't melt easily. Fresh solder on the pad like bubbob42 writes, will help as the flux inside the solder will remove some of that. Also, having a blob of solder on the iron will improve the heat transfer to the pad. More surface area touching = lower thermal resistance.

Often the minus pin of the caps are connected to a ground plane which will 'suck' heat away from the pin you're trying to solder as they act as a heatsink. In this case, a higher temp (and enough power in the iron so it doesn't drop the temperature) and a thicker tip on the iron will help.

Keep going at it on that board. It is possible, and once you find the tricks to it, you're much less likely to damage the Amiga when trying with it.

I'm not sure what you meant about the pin distance?

delshay · 16 July 2013, 22:32

Soldering iron tip polisher.

Viserion · 16 July 2013, 23:52

Prowler: Sorry if I messed up where this should go. As it didn't have anything directly to do with Amiga that is why I chose as I did.

bubbob42: Thank you for the direction. It's a little late right now, but will try this tomorrow.

demolition: Only a few of the caps looked bad. There are relatively many of them on such a small MB. But none of the solder under the MB melted.

I know of the blob of solder trick, and I did try it.

I usally have my iron set to 300, sometimes 350 degrees C.

Max temperature is 450C, and I did try that. But as bubbob42 mentioned, I haven't tried to add a bit of solder first, so that I will try tomorrow.

When positioning the ceramic capacitor there is so little space to supply the solder on to make the connection.

The capacitor covers over the center of the square and the circle, so you can only see a tiny bit of gold shiny bits where you need to apply the solder.

delshay: I have a "golden ball" that I ordered to clean the tip with. Sorry, don't remember what it's called.

demolition · 17 July 2013, 09:56

Quote:

Originally Posted by Viserion

When positioning the ceramic capacitor there is so little space to supply the solder on to make the connection.

Maybe the cap is just too big for the footprint?
Trying to put a 1210 size cap on an 0805 footprint can be hard. Usually better the other way round.

Zetr0 · 17 July 2013, 10:24

@Viserion

Hello there, it does read as though you are in a slight pickle, lets see if I can help.

The A500, alongside A2000 / A1000 and A3000, motherboards do require a little more effort than say an SMT based board, like the A1200 or A600. this is because they have large ground and power planes, and this will suck down the heat and in places act like a large heat-sink.

For reworking motherboards of this area you need a good quality Iron, I have looked your Weller WECP-20 up online (with the powah of google) and can confirm it is sufficient to do the job, (50 watts) you just need to help it a little.

So we need to check the tip of you iron, is it corroded or dull ? if so either replace this tip OR get some "tip-tinner" - theres a few on eBay quite cheap I will post some links at the end of this.

Once we are sure the tip is good condition we need to make things a little easier for the heat to flow - FLUX.... but not just any kind of flux, you need to get NO CLEAN flux - for heavy gauge work like an A500 motherboard I use a flux-paste as this performs really really well and I can comfortable de-solder the through hole components between 280c and 320c (pending track thickness / ground plane)

FLUX removes corrosion on the board and allows the heat to flow uniformly across an area - it will drastically improve your skills by using this stuff.

Now while the product will say NO CLEAN, I promise you now you will need to clean it, in this regard you need to get a bottle of IPA Isopropyl Alcohol - this will help lift and remove any contaminants from the board ensuring nothing nasty or acidic is left behind.

So some links for you

Tip Tinner / Cleaner £6.99
Laco Flux Paste £9.99 + Postage
IPA (Isopropyl Alcohol) £7.50 + Postage

I hope all that helps, if you need any more help, take some pictures of what is challenging you I am sure we can help more =)

Viserion · 17 July 2013, 18:44

demolition: Maybe, but as far as I can remember the ceramics caps I bought was the only size with specifications I needed.

Zetr0: Just to make it clear, I've not tried an Amiga yet, but use a IP9000HD satellite receiver MB as the victim for my attempts to learn this.

The tip I'm using is a few months old, so there should not be any problems there.

I have taken 2 pictures, one of the front, and one of the back. It was very difficult to take as I don't have a good camera. These two turned out half decent.

It might be that the reasons for my trouble is that there is some green/blue stuff covering the MB. It is a little sticky, even if I have cleaned it with something that should contain Isopropyl.

A lot of chemicals is very hard to get for private persons in my country, and I'm uncertain I can buy this of ebay with no problems, or ending up on a list you don't want to be on.

It always been that way, but after the idiot blew up governmental buildings 2 years ago, I think it has become harder.

I have to do a little research first, before I try.

I have a flux pen, and some old paste type flux after my late father, but if this is the usable I don't know. The label says it is corrosive.

bubbob42: Toothpicks don't work well, as the holes are to small for it to fit. But adding a bit of fresh solder did work to some degree. I can't get enough off to remove the pins, but did manage to get some off.

Tried both with the pump, and solder wick. The wick I got is almost useless, but have some on order, so I hope I get it soon.

pandy71 · 17 July 2013, 19:11

Quote:

Originally Posted by Viserion

I have a flux pen, and some old paste type flux after my late father, but if this is the usable I don't know. The label says it is corrosive.

And can't be used for PCB's - unless you can fully clean remains (assume always that you can't).

Quote:

Originally Posted by Viserion

bubbob42: Toothpicks don't work well, as the holes are to small for it to fit. But adding a bit of fresh solder did work to some degree. I can't get enough off to remove the pins, but did manage to get some off.

Tried both with the pump, and solder wick. The wick I got is almost useless, but have some on order, so I hope I get it soon.

First this board use lot of copper ground layers - heat will be quickly spread over PCB - this why people preheat PCB or with special preheater or with hot air gun. Search on YT for movies that cover such aspects of soldering.
for example [ Show youtube player ]
Even ordinary hot air gun with carefully selected temepreture of air and air flow intensity can be used as preheater or even hot air soldering solution - some people fixing in that way cell phones or notebooks.

[ Show youtube player ]

PS

Do not use lead free solder alloy (RoHS compliant) - this is one big fraud in electronics...

Viserion · 17 July 2013, 20:21

Looks like I need to do some shopping again. Will get some flux to use, but have to use a air gun for now, as I've spent enough on Amiga related things this month.

I will look into the YT videos you linked to later.

I use only leaded solder, as I found out that the lead free was no good.

I bought first lead free from the same place I bought the wick from.

Zetr0 · 17 July 2013, 20:48

When dealing with devices prior to 2000, you can legally use non-RoHS compliant (leaded) solder in regards to services such as repairs as well as any adaptor upgrades you may design or make that are to be used on such equipment.

Lead free solder is slightly more difficult to work with for these implementations but its not impossible, when building an IDE adaptor for the Spectrum 128k (+2AB and +3) I used lead free and didn't have much of a problem for it. You just need to know your tolerances and learn the process of flux to solder to heat ratio.

I found myself gaining quite a bit of speed as the lead-free solder does in fact cool very quickly (compared to leaded)

Interestingly there a few industries that are exempt from RoHS regulations regarding lead-free solder, most notably heavy plant (locomotives / exscavators / deep sea / high pressure equipment) as well as any military based electronics. That's not say that new products are not trying to conform to RoHS standards in regards to the use of heavy elements, its just that its the implementation of these products or services are more important for society than the directive.

As you may of guessed its expansion that is the real problem with non-leaded solder - so it can make it's self quite difficult to work on older designs. A lot of problems faced today are not so much the use of the non-leaded solder - but the manufacturing process.

In regards to ordering things like Flux / IPA you shouldn't be having any problems. you can use a reputable company like farnell (EU) or digikey (the later is US related) and you can get your supplies from there.

Quote:

Originally Posted by pandy71

Do not use lead free solder alloy (RoHS compliant) - this is one big fraud in electronics...

I have to admit, in the beginning I was very much of the same opinion - however through practice and production I have leaned to appreciate the importance of reducing heavy element use, not just in the solder but (and this is more so) in the manufacturing process that really can be removed from the food / water table. Some of these elements like chromium and lead are incredibly carcinogenic which if introduced into a food chain or water supply would wreck quite some havock. To be honest were we can we should look to the future to mitigate their damage on society as a whole.

pandy71 · 17 July 2013, 21:44

Quote: