Following another discussion on how to clean up stubborn thruholes, one of the ideas was micro drill bits.
What range of sizes is good to have? Roughly measuring a needle and seeing how it fits in smaller holes, I think 0.5mm or even smaller could be handy. Is there a need for wider than 1mm?
Any thoughts on
these 0.34-1mm bits, drill, pin vise?
Are
double-sided pin vises more useful?
But surely not to drill with?
But surely not to drill with?
Sort of. You insert the needles when the solder is molten to clean out the holes, and it's not unheard of to use a twisting action.
I'm after a real drill for cases where it doesn't melt all the way through.
I'm after a real drill for cases where it doesn't melt all the way through.
How do you plan to solder if you can't get it hot enough to flow properly then?
You might want to rethink your existing soldering iron (no idea what you're using), or perhaps supplementing it with a preheater. FWIW, even the best irons need a preheater if the PCB has enough layers sucking off the heat.
As per drills, if you're set on them, just get a kit like what you're looking at and supplement as needed. But I'm thinking there are larger issues that need to be addressed first (insufficient thermal transfer).
So what's the use case of drilling? I'm trying the simple options available. Some discussion on that already happened in the original™
stubborn thruhole thread.
So what's the use case of drilling? I'm trying the simple options available. Some discussion on that already happened in the original™ stubborn thruhole thread.
Drilling the holes prior to plating them.
Drilling is a last ditch effort at best, as you run a real risk of destroying the hole you're trying to clear. So it's best to try every other possible method first. The needles really do work, and work along the same lines you're after with drill bits (inexpensive too). Other methods were mentioned in the thread you linked, so re-reading those you've not been able to try would be worth it IMHO. Some scrap boards would also be helpful for practicing on before trying on something you really want to repair (regardless of the method).
Really though, I'm under the strong impression you need additional thermal capacity (rather than higher temps) under certain conditions such as ground planes. Not horribly expensive either, and may only need to re-purpose something, such as an unused electric skillet (i.e. it's just gathering dust somewhere). Purpose built preheaters that are reasonably priced can be had as well, such as the
Tenma 21-10135 (Hakko's equivalent is over $300). Hot air guns can also work, but are more clunky and cumbersome to handle IMHO.
Really though, I'm under the strong impression you need additional thermal capacity (rather than higher temps) under certain conditions such as ground planes.
Maybe, but remember, he started this saga by desoldering a capacitor. When he melted the solder to get the capacitor out, he obviously had enough thermal capacity to melt the solder. My guess is that he probably still has enough thermal capacity to melt that same solder in the same hole again, but maybe it's not being conducted to the solder now. More thermal capacity rarely hurts, but careful use of what's there could probably do the trick, if a good thermal conduction path is established between the iron and the solder. That may mean applying a bit more solder above the hole, the way the solder was above the hole when the initial desoldering job was done.
But preheating or using hot air won't hurt, and may help, too.
Maybe, but remember, he started this saga by desoldering a capacitor. When he melted the solder to get the capacitor out, he obviously had enough thermal capacity to melt the solder. My guess is that he probably still has enough thermal capacity to melt that same solder in the same hole again, but maybe it's not being conducted to the solder now. More thermal capacity rarely hurts, but careful use of what's there could probably do the trick, if a good thermal conduction path is established between the iron and the solder. That may mean applying a bit more solder above the hole, the way the solder was above the hole when the initial desoldering job was done.
But preheating or using hot air won't hurt, and may help, too.
The following post from the OP is what led me to my line of thinking.
...at no point the solder melts all the way through the hole. Tried more flux on the board, flux on the braid, another type of braid (new, but fishy), another type of solder (known good and new). The soldering iron is good. Tried up to 480C.
The best I could get is shallow depressions in both sides of the hole, but the middle remained blocked.
It's possible to remove a part if the solder reaches it's plastic range and sufficient mechanical force is applied IME (i.e. pull on part & heat 60/40 simultaneously until it comes out, yet not tear or remove any of the copper off the PCB or hole). Yet even after the part is removed, still can't get enough heat into the joint to fully melt the solder, so it won't clean off/out properly.
nanofrog, AG6QR: I'll reply in the other thread.
If anyone has other drill/bits suggestions...
TAMIYA makes/sell very nice pin vise. I don't recommend drilling a via, it's worst solution I have ever heard. There are more than 4 layers sometimes drilling would break the connections.
Get some low temperature solder or use a 200w ish iron with huge tips, these are cheap and easily available. Do it right, avoid all the monkey tricks.
TAMIYA makes/sell very nice pin vise. I don't recommend drilling a via, it's worst solution I have ever heard. There are more than 4 layers sometimes drilling would break the connections.
Get some low temperature solder or use a 200w ish iron with huge tips, these are cheap and easily available. Do it right, avoid all the monkey tricks.
Unless you're Bill Bixby about to turn into the Hulk, there is no way you can hurt or damage a decent-sized through-hole via with a hand drill and a small wire bit.
I do not understand the resistance to this method, nor the catastrophic scenarios people invoke.
Don't use a 1/2 inch Forstner bit with a press and you'll be fine.
But you're perfectly happy with a 200W iron, and tell people to mysteriously "do it right", as if they can't "do it right" with a small, harmless drill bit.
Baffling.
NO
YES
What is the difficulty?
(funny picture)
Now draw the actual FLEXIBLE drill bit, and the fact that copper is harder than solder, and how does a human hand keep laser-like positional accuracy like that!?
Again, *where* do you people get these infinitely rigid drill bits? And hands capable of drilling at 100000RPM?
Anyone, even me, can whip up catastrophic scenarios in the virtual world. What about reality? You've never seen the copper barrel come out of a via because of a heat-based approach? Really?
I kinda like the MAB 485 idea. It looks cooler. A bit on the expensive side, though.
Hi, over heating is a problem but with a high thermal capacity iron means you can work quickly instead of slow-cooking the board.
Long time experience has taught me that trying to clean out a pesky bit of solder by applying the soldering iron usually will lift the pad. I have used the tiny drill bit method successfully for years. Nothing wrong with that at all.
Long time experience has taught me that trying to clean out a pesky bit of solder by applying the soldering iron usually will lift the pad. I have used the tiny drill bit method successfully for years. Nothing wrong with that at all.
I agree, another tool to get the job done.
When the slow boat arrives with the cheap drill set and motor I will probably take another used Braun toothbrush and made a mini drill out of it. they are easy enough to open and cut the junky bits off the end and make up an epoxy mount that will allow me to make a bushing and shaft for the bits.
Sometimes, after removing the component from the board, some solder is still left in the hole. I have tried adding fresh solder, adding flux, using braid, using suction, using compressed air... sometimes all efforts to remove the last 5% of the solder fails to make the hole clear enough to fit and tight fitting component lead into the hole. In this case, I use wire drill bits
like these in an x-acto knife handle acting as a mandrel. The 40 RPM you get from finger-twisting the drill is just about the perfect speed. Copper is soft, but solder is much softer. I have never damaged a plated this way. I have, however, pulled the plating right out with the component when either too much or too little heat is being added (in combination with far too much force!). I would personally never attempt to drill out a completely solder-filled PTH.
What drill diameters do you find useful?
