EEVblog Electronics Community Forum
Electronics => Beginners => Topic started by: wasyoungonce on September 30, 2016, 04:55:07 am
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Gents...sorry long read:
I'm finding I'm doing more SMD removal and replacements these days and are looking at obtaining/using the easiest cheapest most suitable method for SMD IC removal. I can go either one of 3 ways but want to check with others experience before I commit. I will be doing some tightly packed boards soon and will need a good method of removal. I can solder ICs by hand ok but if I get a bad IC I'll need to be able to remove if and replace. I cannot afford to be damaging PCB pads (especially on some of the commercial units I repair...Losmandy Telescope computers) thus which way should I go, so far I have been fluking it and using quikchip? I have a fair bit of soldering experience but less so with SMDs ..so lets begin:
Method #1: Use my Hakko 936 stations(s) with a 907 iron attachment (http://www.wagneronline.com.au/hakko-900m-smd-barrel/soldering/tools-test/900m-1000-10951/6532/pd/) that allows various SMD IC tips, see down the page (http://www.wagneronline.com.au/soldering-irons-hakko/soldering/tools-test/pl/) to use. The cost of this is actually quite high as I'd need a range of tips. Good part is .....there is a good range of tips even LQFP64 and TQFP32..as well as SOIC8/16; SSOP20/28..etc which I will be doing.
Method #2: Use my Hakko 936 stations(s) and buy one of the Ayuoe T001 hand pieces (a Hakko 950 knockoff) like this (http://www.aoyue.com/en/product/default.asp?id=291). This also has a range of tips that are quite cheap but I don't see any quad package IC tips. The good thing with this is it is cheap, a reasonable range of tips! Down side I'd have to change the plug to a Hakko, but that's no problem. Oh my Hakko 936 is home built exact copy but with 75VA transformers, meaning it can supply the extra power the T001 uses. Another issue here may be calibration of tip heat....not sure what they use as feedback in these knockoffs it may not suit my Hakko 936. Hakko 950-CK hand piece is way to expensive for me...let alone their extra tips.
Method #3: I have a Yihua 858D hot air station but no suitable nozzles for SMD IC's. I can get them cheaply, but, due to some of the PCBs I'll be playing with keeping heat to a minimum and in the right places might be an issue even with copious Kapton tape. Beauty of this is...cheap! Although I must say I'm not a fan of these hot air units...except for using with heat shrink. Maybe I just need to gain more experience using them...I suspect this is very true!
Anyway....what are experiences of others? What do members use and prefer of would use if they could! If indeed spending more is the preferred way to go with best results...then I will do this but wanted feedback before I go down the burrow.
Oh lastly I have a Royel solder/de-solder station and a number of iron (and de-solder iron) (https://www.eevblog.com/forum/testgear/list-your-test-equipment-score-here!/msg1029991/#msg1029991) so I have DIL packages covered. Its just that...de-solder iron is no help on SMDs!
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For removing bad SMD chips? Like as in QFP, SSOP, SOIC, DFN, and the like? I would use hot air station. Nozzle smaller than the body of the IC and blast the IC, not the pins/board. Bad for the IC, of course, but I'm removing it because it's bad, anyway.
If I was working on expensive boards, and I was making good money doing it... then yeah, I might get spendy on tips, too. But the cheap tweezer accessories you might get for a 936, I've had a set or two somewhat like that, and it's not worth it. 936 doesn't even have enough power to remove anything but an 8 pin chip, tops. It might be useful if.. never mind, it would probably never be useful, IMO.
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Thanks for the input.
Yes I was thinking the OEM Hakko 950-CK tweezers would be 25W's per side which is no where near enough. I believe the Aoyue T001's are a little more power ~65W...thus ~ 32.5W per side (my 936 station can handle this with the bigger 75VA transformer). Its higher than the Hakko 950's but not significantly. Your observations parallel my thoughts on this method.
I'm also thinking that a 907 iron with the SMD IC attachments would almost fall into the same trap! Not enough power!
Not really making money doing Telescope computer repairs...barely covering costs! To charge the correct rate...too prohibitive for consumers. For the Telescope computer repairs...just parts cost plus ~10~15%. But looking at building high density Astro camera PCBs as a group project. My part is the PCB drawings and assy! Lucky me! As you said...removal of ICs...they are tossed after this. I'd never re-used a removed IC.
Thus, really looking for a method of removal of bad IC's minimising PCB damage.
I'll order some hot air nozzles for my air station and start practising..oh and more Kapton! At least all this is cheap! Again...many thanks.
Brendan
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You can also fashion some shields out of very thin sheet metal to contain the hot air just around the IC if you'd prefer the DIY route (i.e. rivet or braze the seam).
If you'd rather have ready-made, JBC makes them (Protectors (http://www.jbctools.com/protectors-nitrogen-kit-for-dde-dme-product-553-category-9-menu-70.html)), if you'd rather buy them. Not exactly cheap, but not horrendous either (~$20 per). Versions with a vacuum extractor run ~$40, and a separate vacuum tripod as depicted in the illustration is ~$45.
(http://i.imgur.com/xEFfXjh.png)
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You can also fashion some shields out of very thin sheet metal to contain the hot air just around the IC if you'd prefer the DIY route (i.e. rivet or braze the seam).
If you'd rather have ready-made, JBC makes them (Protectors (http://www.jbctools.com/protectors-nitrogen-kit-for-dde-dme-product-553-category-9-menu-70.html)), if you'd rather buy them. Not exactly cheap, but not horrendous either (~$20 per). Versions with a vacuum extractor run ~$40, and a separate vacuum tripod as depicted in the illustration is ~$45.
Now that's something I didn't know of. I'd seen people fashion shields but would be easy to buy them. The Hakko SMD barrel is $39 AUS alone and each SMD tip is around the same so this shield is way cheaper. :-+
Thanks
Brendan
edit:
Hmmm here's an idea. Use Chip Quik on the SMD ICs pins. Bridge them with an iron and Chip Quik, then use hot air to heat pins all at once. Should work and be easier than using an iron to keep pins at desired heat. The only issue is industrial packs of Chip Quik cost ~ $60 in Australia. Ahhh Oritech has 4.5ft packs for $44 AUS. (http://www.oritech.com.au/701_dash_769/Chip-Quik-SMD-Removal-Alloy-%28SMD4.5%29/pd.php). That's better and cheaper than RS; Ele14; Upton and MEK.
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Hmmm here's an idea. Use Chip Quik on the SMD ICs pins. Bridge them with an iron and Chip Quik, then use hot air to heat pins all at once. Should work and be easier than using an iron to keep pins at desired heat. The only issue is industrial packs of Chip Quik cost ~ $60 in Australia. Ahhh Oritech has 4.5ft packs for $44 AUS. (http://www.oritech.com.au/701_dash_769/Chip-Quik-SMD-Removal-Alloy-%28SMD4.5%29/pd.php). That's better and cheaper than RS; Ele14; Upton and MEK.
You could, but I suspect Chip-Quik won't be necessary with a shield.
Do you have a spare or scrap board of similar specs you can place a thermocouple/s on to test PCB temps?
Could save you a good bit of funds, particularly down the road. ;D
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I've always found tweezer irons a pain as it's hard to get them lined up right, and the parts stick to them & can be a fiddle to unstick.
A MUCH quicker and easier method is to use two irons, one in each hand - gives much more control.
https://www.youtube.com/watch?v=eOYsAHHs2RA (https://www.youtube.com/watch?v=eOYsAHHs2RA)
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Hi Mike and nanofrog. I've used 2 iron SOIC16 SMD removal before, quite a few times...no Chip Quik. Since it was only every once in awhile I didn't bother looking for other methods. I have also done a few SOIC32 SRAM ICs like this as well. That was more difficult!
But nowdays.....my helper went on strike...she got burnt and blamed me! :-//
I have some scrap boards I'll play with and test temperatures. Damn fine idea!
Brendan
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For anything with more pins than you can get an iron on, hot air is the quickest & easiest
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Hi Mike...yep that's the conclusion I came to...and kinda knew before asking, but it doesn't hurt to ask.
I've tried using my hot air station on some junk PCBs to see how it goes and found some big items need a lot of heat and for delicate areas you need to "Dam" it up with Kapton tape to protect other components from excess heat. Using Chip Quik will reduce this "excess heat" issue greatly. I have a Vac desolder station but it's pretty useless for SMD and indeed I always got away with DIL thru hole packages by cutting the legs carefully then a quick heat and tweezers to remove the left over pin. This method also works with most thru hole stuff even electros etc. Cut the package, leave the legs.
That said..I was scavenging Sony ICX453AQ camera sensors recently (from Nikon cameras) and the VAC de-solder came into its own here.
Now days I'm doing more and more SMD and need to re-invent my methods. Again many thanks I'm on the right track now.
Brendan
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One vital tip for using hot air - leave the tool to warm up fully before using - at least a minute.
If it's not hot enough, or still warming up, you can cause more damage as you need the heat for longer. Once stable you have good control by adjusting distance.
And of course use plenty of flux. As well as making life generally easier, it acts as a visible temperature indicator as it bubbles & evaporates.
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One vital tip for using hot air - leave the tool to warm up fully before using - at least a minute.
If it's a large board and/or thick pour, you can waste the minute preheating the surrounding area. :) Unless there are plastic connectors nearby, I don't usually fuss over heating other nearby components. The one you're after is going to reach melt point, first, just be careful to not dislodge the surrounding caps/resistors when you lift it off. Heat shield is sometimes necessary, but I would think it can cause thermal expansion stress in the surrounding joints.
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Heat shield is sometimes necessary, but I would think it can cause thermal expansion stress in the surrounding joints.
Preheat at a lower temp, say 150C max for a minute or so, then ramp the temp up to what's needed to solder/desolder. It also helps with ground pours and the like.
FWIW, I use the presets on mine for this purpose (i.e. poor man's reflow profile implementation sans an oven). >:D
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Annnd here is what $65 buys...
At least its cheaper than the SMD IC adaptor tips or Hakko 950 tweezers (or knock off)...including lots of tips needed.
Time to practice I think. Many thanks you everyone's input
Brendan