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Old 16th January 2008, 02:49 PM   #1
johnm is offline johnm  United Kingdom
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Default Calling any UK SMD soldering experts!

Hi there!

I have a Amp4 which has been sitting in a drawer gathering dust for over 6 months. Reason being the two SMD chips just look too daunting to me to solder into place, and I don't really have the gear necessary to do it properly, and I don't want to damaneg anything. The other SMD components are fine, but the two Tripath chips I need help with.

Would any kind soul be willing to solder these into place for me, in exchange for some beer type monies PayPal'd to them? Just leave the beer until AFTER the soldering !!!

Many thanks,

- John
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Old 16th January 2008, 03:53 PM   #2
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These are PSOP packages aren't they?

The way I learnt to solder these was to make sure you've got a nice clean reel of solder wick (solder braid) handy.

1. You pre-tin the pads (assuming it's a gold-plated pcb, if it's tin plated then you don't need to do this). After pre-tinning, use the solder wick to take of the solder, leaving a very thin coating on the pads.

2. Melt a small amount of solder onto a corner pad. (You'll need to use proper very thin SMD solder and a good quality thin-tip iron)

4. Using fine tweezers, position the chip on the pads and carefully solder the correct corner pin onto the pre-tinned pad.

5. Hopefully you can now slightly rotate the chip to be correctly positioned on the pads. If not, re-position the chip on its corner pad.

6. When the chip is positioned correctly, solder the diametrically opposite pin to keep the chip located.

7. Now you flood-solder the pins on both sides. This will give you most of the pins on each side joined together and will look a horrible mess!

8. This is where the new reel of solder wick is used. Place the end of the wick on one (or two) of the pins, and put the soldering iron on top of the wick. When the solder melts it will get absorbed into the wick, so you then draw the wick away from the chip keeping it in-line with the pin. The excess solder in that area gets removed and the surface tension of the solder draws the remainder back onto the pins and pads. Use 60/40 solder, not lead-free as lead-free seems to have less surface tension.

9. Go round the rest of the chip, snipping of the used part of the solder wick first.

It sounds tricky, but when you get used to it you can produce very good soldered joints even on TSOP/MSOP/PSOP devices!

If you want a scrap commercial board with suitable chips on to practice on I'll post you one!
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Old 16th January 2008, 06:22 PM   #3
BWRX is offline BWRX  United States
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I'm not in the UK but I'd gladly solder the chips if you're willing to pay postage to send them back.
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Old 16th January 2008, 07:03 PM   #4
AuroraB is offline AuroraB  Norway
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A ligh coating of fresh no-clean flux tremendously eases the job.
Flux is available as marking type pens - quite handy for the small scale user.

Solder should not be thicker than .5 - .8mm, or get a tube of paste solder. you should seriously concider the offer for the practice board... or even buy a practice kit.
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Old 17th January 2008, 11:02 AM   #5
Gorilla is offline Gorilla  United Kingdom
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Default tutorial video

Have a look at this video. It is a really great tutorial. The site itself also has some good written advice.

I'd offer to help too, but I've only just moved to the UK and have no equipment .
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Old 17th January 2008, 11:31 AM   #6
johnm is offline johnm  United Kingdom
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Thanks for all the help and offers guys - truly appreciated

You've all convinced me to take a shot at this myself. Ouroboros would it be OK to take you up on the offer of that practice board? If I don't have much luck with that then I'll consider getting someone to solder those chips for me (thanks for the offer BWRX).


- John
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Old 17th January 2008, 11:38 AM   #7
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Ok, drop me an email via the site and I'll have a look in my R&D sample pile here at work for suitable chips and bare pcbs for you to have a go on. I doubt if I'll get it posted off to you before the weekend though.

best of luck!
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Old 17th January 2008, 01:09 PM   #8
Bobken is offline Bobken  United Kingdom
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Hi John,

I would encourage you to have a go at this for yourself, and you will learn a lot in the process.

Having made a good living out of soldering (and I have been soldering for around 60 yrs.) I found the video suggested by Gorilla to be truly excellent. The techniques are sound, and the likely pitfalls are sensibly explained.

I am sure that if you follow it carefully and take your time, you will succeed.

Good luck, anyway.

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