Electronic – Is it safe to rub WD-40 in to a brass insert on a circuit board

pcbsafety

I am trying to replace the SSD on a laptop. After a Loctite nightmare that I had while getting the casing off, there's just one last screw between me and getting the job done. Despite being confident that I've got the right screwdriver (a 000 Philips), the thing just won't budge. On top of my fear that I may have threaded the screw, I'm worried that I'm fighting Loctite again.

Fortunately, I know that a common Loctite removal trick involves dabbing some WD-40 on the screw with a cotton bud, letting it soak in, and then doing it again before trying to remove the screw normally. I'm ready to attempt this, but I just can't shake the feeling that WD-40 and circuit boards shouldn't mix.

Is it safe for me to put WD-40 so near to my circuitry? I've included a picture below. I'm hoping for the WD-40 to be contained by the (presumably brass) insert. Better yet, I'm hoping that I'm simply misremembering how WD-40 reacts to PCB.
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Note: It has been quite rightly said that this appears to be an x/y question, so I will make this note for future readers. The answers given appear to show that WD-40 is safe, which is all that was asked for and is indeed an answer. However, my research indicates that it will be ineffective. This here is the spec sheet for blue Loctite, which is one of the weaker forms of Loctite. Of note, it says that the Loctite only loses 15% of its strength after 500 hours of exposure to acetone. If acetone can only just barely do the job, then I suspect that WD-40 won't be able to do the job at all. In short, this question and its answers seem to show that WD-40 will be safe, but ineffective.

Best Answer

Putting WD-40, which has lubricating properties, on your screws and threads is not a great idea, especially in tight spaces where you won't have much of a way to wash it off with solvent afterwards. As you noted, many of these screws were secured with Locktite, which is usually done to prevent them from loosening due to vibration and other forces acting on the parts they hold together. By applying WD-40, unless it's subsequently washed off, you're doing the exact opposite of what was intended with Locktite - you're making the screw even more prone to loosening than it would normally be without any additives applied.

The reason why WD-40 helps defeat Locktite is a combination of its lubricating properties (which are undesirable for screws) and its solvent content. Solvent would be perfectly appropriate to apply on screws and threads, so if chemicals are your preferred method here, you might want to try isopropyl alcohol (which is not a very aggressive solvent and should be safe to use around most electronics components) or some more serious solvent like acetone. With acetone or any other aggressive solvent, you'll need to be careful not to spill it onto the PCB and the plastic parts around it, because it will soften and dissolve plastics, soldermask, legend print on the PCB and possibly parts of some of the components. It's also really important to have very good ventilation when working with chemicals like acetone, for health reasons.

As others already pointed out, another widely accepted method of defeating Locktite is by applying heat. If I were you, I'd pick that route - the risk of damaging electronics at these temperatures is low, and I wouldn't be compromising my mechanical connections the way I would have by using WD-40. For the source of heat, you can use a soldering iron (with its temperature set to 150-180 °C [300-360 °F], or if that's not possible, just carefully limiting how long it's touching the screw should be fine) or a clothes iron set to the highest temperature, if you can fit the tip of the soleplate in there.

When it comes to actually gripping the stripped screw head, avoid methods that create metal dust - you don't want that on your electronics. Prefer using a tool that bites into the screw head instead. Apart from others' great suggestions, there's one other suitable tool that you may have lying around - a small end-cutter. If the blades of your particular cutter extend all the way to the sides of the jaws, you should be able to carefully make them bite into the edge of the screw head, holding the tool horizontally (ie. in the plane of the top face of the screw head). That way, you'd have excellent mechanical advantage to turn the screw, as long as you're very careful not to allow the jaws to slip off the head.

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