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Hints, Tips and Solutions (Do NOT post requests for help here) If you have any useful general hints and tips for vintage technology repair and restoration, please share them here. PLEASE DO NOT POST REQUESTS FOR HELP HERE! |
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30th Nov 2017, 4:56 am | #1 |
Heptode
Join Date: Oct 2005
Location: Olympia, Washington, USA.
Posts: 664
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Surface mount parts- RIP. (Rest in Place)
While replacing some SMT parts in TV sets, I had a ****** of a time getting them to stay in place while I soldered them. After a mutual grumbling session with my friends, one of the girls suggested eye lash glue.
Use the Latex base stuff. (If it smells like ammonia, don't use it). A pin point size drop of the clear stuff, properly dried, held the parts just fine. Non- conductive too, if you don't use the black stuff. It took some experimenting, but the gal at the local makeup counter was delighted to sell me 5-6 different types to putter with. One tube will likely last for hundreds & hundreds of parts. Oh, yeah, be sure to put the cap back on tightly too. It turns into a rubbery blob if you don't. The black type seems somewhat conductive, as I think an ingredient is carbon black or charcoal for the coloring. At least the stuff I tried was conductive on the meter. I ran 1" strips of it on glass, and measured conductivity with my meter. One result of this was my SO had a many years supply of the types that were not suitable. Some of the adhesive types had chemicals in it that I was not sure would be safe for the chips and components. |
30th Nov 2017, 5:16 am | #2 |
Banned
Join Date: Dec 2013
Location: Middlewich, Cheshire, UK. & Winter in the Philippines.
Posts: 3,897
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Re: Surface mount parts- RIP. (Rest in Place)
Now then, you may have hit a bull's eye there with a bit of lateral thought.
Conductive silver paint is hellish expensive but black lash glue isn't. Food for thought? |
30th Nov 2017, 7:47 am | #3 |
Moderator
Join Date: Mar 2012
Location: Fife, Scotland, UK.
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Re: Surface mount parts- RIP. (Rest in Place)
Paint-on resistor!
DIY answer to screened and fired thick film hybrids? David
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30th Nov 2017, 11:28 am | #4 |
Tetrode
Join Date: Apr 2013
Location: Cambridge, Cambs. UK.
Posts: 71
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Re: Surface mount parts- RIP. (Rest in Place)
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30th Nov 2017, 11:46 am | #5 |
Moderator
Join Date: Jun 2003
Location: Oxford, UK
Posts: 27,939
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Re: Surface mount parts- RIP. (Rest in Place)
I wonder if a dab of nail varnish would also work as an adhesive?
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30th Nov 2017, 12:24 pm | #6 |
Dekatron
Join Date: Nov 2003
Location: Heckmondwike, West Yorkshire, UK.
Posts: 9,642
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Re: Surface mount parts- RIP. (Rest in Place)
What goes around!
I seem to remember that early grid leak resistors were sometimes made by soaking cardboard with Indian Ink. |
30th Nov 2017, 1:55 pm | #7 | |
Dekatron
Join Date: Apr 2009
Location: Oxfordshire, UK.
Posts: 4,934
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Re: Surface mount parts- RIP. (Rest in Place)
Quote:
B
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30th Nov 2017, 2:21 pm | #8 |
Dekatron
Join Date: Jun 2016
Location: London, UK.
Posts: 3,687
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Re: Surface mount parts- RIP. (Rest in Place)
They're pretty easy to get to stay put. My trick, which requires no glue is:
1. Tin the pad slightly. 2. Get some tweezers, stick the part on top of the pad and just heat it to tack solder it. 3. Solder diagonally the other end. 4. Solder the original end again. 5. Solder the rest of the pins. 6. Clean up with wick, then IPA. I've done this about 500 times now and no glue required! Works down to 0402's, TSSOP, SOIC, SOTs, the lot. Using these tweezers, which are worth the cost: https://uk.rs-online.com/web/p/tweezers/8348161/ |
30th Nov 2017, 8:04 pm | #9 |
Dekatron
Join Date: Jun 2009
Location: Staffordshire Moorlands, UK.
Posts: 5,270
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Re: Surface mount parts- RIP. (Rest in Place)
Yes, a good pair of non-magnetic tweezers, and then flux.
I'm not keen on glueing these things down. Although essential for high speed pick & place machines, some smt glue (ie the stuff actually meant for the job) has been found to turn conductive after some years. One product in particular I can think off had a raft of mods to overcome random pcb leaks caused by dots of glue under capacitors. I'd have never found such faults without access to the manufacturer's bulletin.
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1st Dec 2017, 12:42 am | #10 | |
Dekatron
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Location: Leominster, Herefordshire, UK.
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Re: Surface mount parts- RIP. (Rest in Place)
Quote:
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1st Dec 2017, 7:56 am | #11 |
Dekatron
Join Date: Jun 2016
Location: London, UK.
Posts: 3,687
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Re: Surface mount parts- RIP. (Rest in Place)
Street cred
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1st Dec 2017, 8:06 pm | #12 |
Octode
Join Date: Jan 2005
Location: Hyde, Greater Manchester, UK.
Posts: 1,074
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Re: Surface mount parts- RIP. (Rest in Place)
When i was in the PC repair business I used nail varnish as anti tamper seal, so much cheeper (free if your GF doesnt notice it missing )
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1st Dec 2017, 10:51 pm | #13 | |
Dekatron
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Location: Lynton, N. Devon, UK.
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Re: Surface mount parts- RIP. (Rest in Place)
Quote:
I usually tack SM parts down on one pin or pad, like MrBungle. Or I use a cocktail stick to hold it down, and flood the whole thing with solder, afterwards draining it away by holding the board upside-down and visiting the iron underneath. I definitely don't like any glue if I can help it! |
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2nd Dec 2017, 8:39 pm | #14 |
Hexode
Join Date: Jan 2011
Location: Aberdare, South Wales, UK
Posts: 403
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Re: Surface mount parts- RIP. (Rest in Place)
As someone who did all the company SMD repairs and prototypes, I can say that I have NEVER glued any components to the board. Totally unnecessary.
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Richard |
6th Dec 2017, 8:15 pm | #15 | |
Dekatron
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Location: Newcastle, Tyne and Wear, UK.
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Re: Surface mount parts- RIP. (Rest in Place)
Quote:
For smaller 2-pin, three pin devices and small ICs of up to about 16 pins I clear all the pads of solder and then put a shallow blob of solder on just one pad which I melt while manouvreing the part into place. That single spot of solder then holds the device in place while I solder the rest. -But. The OP's discovery of the conductive version of this goo makes it sound like a promising repair agent for those rubber membrane keypads whose conductive rubber button 'carbon pills' no longer conduct. |
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7th Dec 2017, 3:11 pm | #16 |
Dekatron
Join Date: Apr 2005
Location: North Wales, UK.
Posts: 6,916
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Re: Surface mount parts- RIP. (Rest in Place)
I've always found that introducing glue under an SMD IC is a mistake as it causes the chip to be too high. Like Sirius above, I find if the pads are completely clean the IC will sit square on them. A small blob on one corner (assuming a quad) then a little manipulation with the tweezers and a blob on the opposite corner and then the solder will take. If the pins are even fractionally above the pads then you can't do a good job. And what if you need to remove the new IC?
Glyn |
4th Jan 2018, 2:42 am | #17 |
Heptode
Join Date: Oct 2005
Location: Olympia, Washington, USA.
Posts: 664
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Re: Surface mount parts- RIP. (Rest in Place)
I never had any removal problem with the eye lash glue, if I had to change out the part.
Remember I said a "pinpoint" amount. I worked on mass consumer electronics and often turning the boards upside down, etc. was not an option. I had to work with the boards at odd angles, and getting a SMT part to stay in place long enuf to tack it with solder was nigh onto impossible. The" conductive glue" thing was rampant in consumer electronics here in the States. I remember having to remove it from many Pioneer, PCE, and other brand stereo receivers and TV sets, and even car radios. |
4th Jan 2018, 6:30 am | #18 |
Moderator
Join Date: Mar 2012
Location: Fife, Scotland, UK.
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Re: Surface mount parts- RIP. (Rest in Place)
Appropriate to the title of the thread, when badly located SMT parts stand on end due to surface tension on one end exceeding that on the other when the solder melts, it is called 'Tombstoning'
For use as prodders when soldering, tagstrips , T-H PCB, or SMT, cocktail sticks are rather useful. HP had them set up in stores, complete with part number. Guess who set up a part number for "Washer, Non-Ferrous, Mint Flavor" ? (American simplified spelling and engineering drawing included) David
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4th Jan 2018, 7:33 am | #19 |
Nonode
Join Date: Aug 2010
Location: Resolven, Wales; and Bristol, England
Posts: 2,608
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Re: Surface mount parts- RIP. (Rest in Place)
Did you also set up a part number for “Olives, stoned, green”?
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Richard Index: recursive loop: see recursive loop |
5th Jan 2018, 9:11 pm | #20 | |
Dekatron
Join Date: Feb 2007
Location: Leominster, Herefordshire, UK.
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Re: Surface mount parts- RIP. (Rest in Place)
Quote:
Someone in need of a lifesaver? There must be a way to get chukka in there somewhere. Maybe it's how long the washer lasts?
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....__________ ....|____||__|__\_____ .=.| _---\__|__|_---_|. .........O..Chris....O |
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