# Securing mod wires to PCB

I have done a few mods to a PCB with 36 gauge mod wire. Obviously this wire is so thin that it only takes a few bends back and forth to break it. What is the best way to secure this in place on the PCB? I have tried super glue but that makes a mess because it flows too easily.

• There's gel type superglue that's far easier to use than the normal low viscosity fluid, but even that is likely to slump before setting unless you spray it with an activator to set it quickly. There are two part epoxies that I've used to good effect in similar circumstances, the quick set (5 minute) stuff will begin thickening within a minute or so, so you can time when to drop the mix into place if you want to build up a supporting collar around the joint. – Phil G Jun 28 at 21:41

At work I use Dow Corning 3145 RTV silicone adhesive for this very purpose. We also use it to secure flex cables in their connectors, secure right-angle parts such as capacitors to the board surface, fill small gaps to make the product waterproof, electrical component insulation, and so on. It is chemical-resistant, water-resistant, corrosion-resistant, non-conductive, and sticks to just about anything. There are many different uses for it, and in my opinion it is absolutely indispensable.

And to prevent this from being a specific product plug (I am not affiliated with the company in any way, I just like the product), I will say that just about any silicone adhesive designed for printed circuit board use will probably work great in this sort of application.

• Beware this is extremely different than hardware store RTV silicone! The hardware store product is hazardous to electronics as unlike this it releases acetic acid while it cures. – Chris Stratton Jun 29 at 2:50
• @ChrisStratton Thank you very much for emphasizing this. I have changed the text in my answer to bold italics clarifying that it must be PCB-grade RTV. – DerStrom8 Jun 29 at 3:09
• What's the shelf life of that kind of RTV? It's always like \$60+ for a few dozen mL and I'm hesitant to spend money on it since whenever I need some it's never very much. – DKNguyen Jun 29 at 5:26
• From the technical data sheet: When stored at or below 30°C in the original unopened containers, this product has a usable life of 12 months from the date of production. – DerStrom8 Jun 29 at 11:23
• @DerStrom8 This was my final solution. It worked very well. Thank you. – user8908459 Jul 3 at 20:55

Kapton tape.

Enamel paint. (Nail polish might even work in a pinch.)

Hot glue for larger wires.

Use a needle which you dip into the super glue to make tiny glue dot and (right angled) tweezers to keep the modification wire in place.
Or use hot melt; same procedure.
Hot melt has the benefit you can melt it again and you can kind of control the cool down using your hot air station.

Our PCB EMS facility used wire similar to WW AWG30 or smaller , soldered and Loctite bonded with 1 part instant adhesive for strain relief from vibration. 1 glue dot per 5 cm.

I prefer annealed magnet wire. AWG30 or smaller.

I was Eng Mgr for C-MAC WINNIPEG and global Design Services Mgr with over 100 factories now all sold twice and owned by the largest EMS provider overseas.

• Do you have more specifics on the Loctite product? – user8908459 Jun 28 at 21:50
• 20yrs ago , no I forget the model number 647? but pretty common low viscosity, and used under clean air flow control for OSHA. – Tony Stewart Sunnyskyguy EE75 Jun 28 at 21:52
• But for large mass strain relief, most use some PU white dispensers, I just use PLC4000 but to high volatile former versions were stronger for heavy parts and fast drying. – Tony Stewart Sunnyskyguy EE75 Jun 28 at 21:54
• Isn't Loctite instant adhesive pretty much just super glue? – user8908459 Jun 28 at 21:54
• Yes except they have more than a dozen flavours , 1 or 2 part, more and less carcinogenic and always kept in the freezer. Some for medical surgery. – Tony Stewart Sunnyskyguy EE75 Jun 28 at 21:55