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-   -   Surface mount parts- RIP. (Rest in Place) (https://www.vintage-radio.net/forum/showthread.php?t=141784)

FrankB 30th Nov 2017 4:56 am

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.

Boater Sam 30th Nov 2017 5:16 am

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?

Radio Wrangler 30th Nov 2017 7:47 am

Re: Surface mount parts- RIP. (Rest in Place)
 
Paint-on resistor!

DIY answer to screened and fired thick film hybrids?

David

Colin G8TMV 30th Nov 2017 11:28 am

Re: Surface mount parts- RIP. (Rest in Place)
 
Quote:

Originally Posted by Radio Wrangler (Post 995580)
Paint-on resistor!

A company I do some work for makes equipment for testing printing inks. They have recently been involved with a different company doing research into printable electronics, including *active* components.

paulsherwin 30th Nov 2017 11:46 am

Re: Surface mount parts- RIP. (Rest in Place)
 
I wonder if a dab of nail varnish would also work as an adhesive?

AC/HL 30th Nov 2017 12:24 pm

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.

Bazz4CQJ 30th Nov 2017 1:55 pm

Re: Surface mount parts- RIP. (Rest in Place)
 
Quote:

Originally Posted by paulsherwin (Post 995615)
I wonder if a dab of nail varnish would also work as an adhesive?

As a kid I used to collect my sister's discarded nail varnishes and used them for all kinds of odd tasks, e.g. fixing coils in place on formers. Ah... the smell of nail varnish :o.

B

MrBungle 30th Nov 2017 2:21 pm

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/

McMurdo 30th Nov 2017 8:04 pm

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.

Herald1360 1st Dec 2017 12:42 am

Re: Surface mount parts- RIP. (Rest in Place)
 
Quote:

Originally Posted by Bazz4CQJ (Post 995650)
As a kid I used to collect my sister's discarded nail varnishes and used them for all kinds of odd tasks, e.g. fixing coils in place on formers. Ah... the smell of nail varnish

If anyone can show me the difference between RS anti tamper seal and red nail varnish, I'd be interested......

:)

MrBungle 1st Dec 2017 7:56 am

Re: Surface mount parts- RIP. (Rest in Place)
 
Street cred :)

jay_oldstuff 1st Dec 2017 8:06 pm

Re: Surface mount parts- RIP. (Rest in Place)
 
Quote:

Originally Posted by Herald1360 (Post 995841)
If anyone can show me the difference between RS anti tamper seal and red nail varnish, I'd be interested......

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 ;) )

kalee20 1st Dec 2017 10:51 pm

Re: Surface mount parts- RIP. (Rest in Place)
 
Quote:

Originally Posted by Herald1360 (Post 995841)
Quote:

Originally Posted by Bazz4CQJ (Post 995650)
As a kid I used to collect my sister's discarded nail varnishes and used them for all kinds of odd tasks, e.g. fixing coils in place on formers. Ah... the smell of nail varnish

If anyone can show me the difference between RS anti tamper seal and red nail varnish, I'd be interested...

Now there's a thing - if I was a girl, I'd want to paint my nails with the RS varnish. May not get the street cred- but definitely lab cred!

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!

trickie_dickie 2nd Dec 2017 8:39 pm

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.

SiriusHardware 6th Dec 2017 8:15 pm

Re: Surface mount parts- RIP. (Rest in Place)
 
Quote:

Originally Posted by trickie_dickie (Post 996286)
I have NEVER glued any components to the board. Totally unnecessary.

I have to agree - I solder SMD devices every day including some very fine pitch quad sided ICs and I just manouvre those into place while looking straight down on top of them through a magnifier and solder two opposite corner pins, briefly melting and moving one or the other again if necessary until the IC is dead in position. Then I solder the rest.

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.

Welsh Anorak 7th Dec 2017 3:11 pm

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

FrankB 4th Jan 2018 2:42 am

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.

Radio Wrangler 4th Jan 2018 6:30 am

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

mole42uk 4th Jan 2018 7:33 am

Re: Surface mount parts- RIP. (Rest in Place)
 
Did you also set up a part number for “Olives, stoned, green”?

Herald1360 5th Jan 2018 9:11 pm

Re: Surface mount parts- RIP. (Rest in Place)
 
Quote:

Originally Posted by Radio Wrangler (Post 1004757)
Guess who set up a part number for "Washer, Non-Ferrous, Mint Flavor" ? (American simplified spelling and engineering drawing included)

David


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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