Temporary SMD Adhesives?

Question

When I do prototyping I solder my PCBs by hand. That works fine most of the time, but I run into a problem when I have to solder chips with fine pitch (Google for VQ100 to get an idea of what I'm working with). The problem is not the soldering by itself but keeping the parts in place once the pins are aligned to the pads.

Now I'm looking for an adhesive that lets me temporarily stick a large SMD component onto the board so it does not slip away as soon as I touch the pins with my soldering tip.

During a Google search I found a log of SMD adhesives, but all of them are resistant to PCB cleaning substances. I need the exact opposite. Something that lets me temporarily stick a part onto the PCB and dissolves fast in PCB cleaning chemicals (I use isopropyl alcohol if that matters).

Something with the sticky properties like thick honey would work except that I'm looking for a more professional solution.

I'm certainly not the first one to look into this, so there must be a ready made product out there, right?

I always just put the part down loosely then tack a corner. I can knock it into place with my pick while keeping the pin hot and align it that way. Tack opposite corner and solder away. Works even for qfns, of course now that I've learned to skillet reflow this is a rework only approach for me. — Some Hardware Guy, Jun 08 '15 at 23:56

score 3 · Answer 1 · answered Jun 08 '15 at 23:34

I've used Kapton tape in the past for larger ICs that I need to keep down. Smaller ICs can be addressed by placing a small amount of solder paste on a corner pad. Place part and REflowing that corner pin. Very Small shifts can then be made to part before soldering the other corners then rest of pins.

score 1 · Accepted Answer · answered Jun 08 '15 at 22:46

Have you tried bog standard thermal glue? They are not particularly strong, and the component can be slid with modest force to release from adhesion. The glue can be scraped off fairly easily, I don't know what solvent would remove it, but I can't imagine it would be easy to find one that does it. An alternative idea would be using a magnet or suction device to hold onto the component, and then position it with a clamp - or in fact just use a clamp of sorts on its own. I believe the suction and/or electromagnets are what is used in automated PCB manufacturing robotics for placing the components.

Why do you need to remove the device after soldering? I'm missing something here. Once it's soldered, why would you need to remove the adhesive?

That idea with a magnet is great! I'll try that. – Nils Pipenbrinck Jun 08 '15 at 23:09 — Nils Pipenbrinck, Jun 08 '15 at 23:09

score 1 · Answer 3 · answered Jun 08 '15 at 23:24

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You might try RTV compound (its rubberized so relatively easy to peel off) or double sided tape between the component and board.

answered Jun 08 '15 at 23:24

user3169

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score 1 · Answer 4 · answered Jun 09 '15 at 01:04

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The standard stuff that most people use is something called "blue tack". This is available at many office supply stores.

You can also use silly putty or modeling clay.

You need to use only a very tiny amount.

answered Jun 09 '15 at 01:04

Dwayne Reid

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Temporary SMD Adhesives?

4 Answers4