Author Topic: Cleaning up solder from a stubborn thruhole  (Read 13061 times)

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Offline atferrari

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Re: Cleaning up solder from a stubborn thruhole
« Reply #26 on: November 15, 2014, 11:39:26 pm »
Sometimes force is the only thing that can work. A de-soldering station with vacuum pump would probably clear it. If you don't have one you could try heating it and poking out the solder with something like a toothpick before it solidifies.

I have always kind of a toothpick around for those cases.  :-+
Agustín Tomás
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Offline kxenos

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Re: Cleaning up solder from a stubborn thruhole
« Reply #27 on: November 16, 2014, 02:57:53 am »
Thanks everyone.

I tried what I could of the above. I can't push anything through because 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. I suspect something blocks heat transfer in the middle. Is that a common occurrence, and any idea what and why that might be?

Those drill bits, what range of mm sizes is useful for this?

BTW, in some cases when touching the iron to the hole something creaked. Maybe the board, but not sure. Common thing? A bad sign? :)

I'm afraid the next suggestion will suggest a kitchen oven...  ;)
 

Offline pickle9000

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Re: Cleaning up solder from a stubborn thruhole
« Reply #28 on: November 16, 2014, 03:26:05 am »
If you can melt the solder use these:

http://www.ebay.ca/itm/Hollow-needles-desoldering-tool-for-electronic-components-/370723601236?pt=LH_DefaultDomain_0&hash=item5650d93b54

If you can't melt the solder measure the diameter of the wire of the replacement component. 

Get a pin vise http://www.ebay.ca/sch/i.html?_from=R40&_sacat=0&LH_BIN=1&_nkw=pin+vise&rt=nc&_pppn=r1&LH_FS=1

Get some bits http://www.ebay.ca/sch/i.html?_odkw=pcb+drill+bits&_from=R40|R40&LH_BIN=1&LH_FS=1&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313&_nkw=pcb+drill+bits+set&_sacat=0

I prefer plain old hss twist bits. Manually drill the hole, be gentle. Take 3 minutes or so . For things like caps you can flush cut with snips and leave the lead in place. The trick is not to use a large bit, even if you destroy part of the thru hole the small bit keeps most of it intact. Having said that if you have the hole partially clear and can't get the lead through this method should not be used. The bit can screw in and detach the plating. Better to fill the hole and drill it out.

Stuff like this is always handy to have on the bench, of course a preheater is also an option.
 

Offline BradC

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Re: Cleaning up solder from a stubborn thruhole
« Reply #29 on: November 16, 2014, 04:19:49 am »
The soldering iron is good. Tried up to 480C.

Actually the problem is your iron. If your iron was any good and had a real 480C at the tip when you had it buried in the hole you'd push right through. Your iron is either
A) Lying to you (never seen a properly calibrated whoflungpoo iron out of the box)
B) having sufficient thermal resistance between the heater and the tip that the board is sucking the heat out faster than the iron can keep up (ie crap iron/tip)
C) Woefully undersized

Now, you can either preheat the board (I use an Aoyue hot air gun held in a chemistry retort stand and clamp for positioning) or get a better iron. None of the suggested fixes will work until you can properly melt _all_ the solder.

If your iron is a JBC, Hakko or Metcal then you are using it wrong. If it's not then it's likely too small or badly engineered. I have 3 irons here, all cheap Aoyue handles. One of them has had the heater replaced with a genuine Hakko unit, and all have genuine Hakko tips on them. The upgraded unit is far better at thermal conductivity than the others and sees the most use. I have the extras as at $17 each it's easier to swap irons than tips, so I have irons ready with all the other tips I commonly use.

Take another long hard look at your iron.
 

Offline G7PSK

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Re: Cleaning up solder from a stubborn thruhole
« Reply #30 on: November 16, 2014, 09:43:45 am »
Nozzle cleaners (for gas torches) are very good for cleaning through holes in PCB's Start small and work up to the correct size and unless you are very brutal there is no damage to the copper plating.

http://www.ebay.co.uk/itm/1-X-NOZZLE-CLEANER-SET-SPECIAL-OFFER-/180468427507?pt=LH_DefaultDomain_3&hash=item2a04c1aaf3
 

Offline dfmischler

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Re: Cleaning up solder from a stubborn thruhole
« Reply #31 on: November 16, 2014, 12:33:05 pm »
A) Lying to you (never seen a properly calibrated whoflungpoo iron out of the box)
B) having sufficient thermal resistance between the heater and the tip that the board is sucking the heat out faster than the iron can keep up (ie crap iron/tip)
C) Woefully undersized
D) Not moving heat because it is not properly tinned.
 

Offline lpc32

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Re: Cleaning up solder from a stubborn thruhole
« Reply #32 on: November 16, 2014, 03:04:09 pm »
Let's see some pictures


(How's that for guerrilla marketing? :))

Iron and tip: Hakko FX-888D with probably T18-D16 (chisel, ~1.5mm). It's tinned, etc.

If your iron is a JBC, Hakko or Metcal then you are using it wrong.
It's not an Apple iron. But yes, anything's possible, though it worked mostly okay for other holes.

If you can melt the solder use these:

http://www.ebay.ca/itm/Hollow-needles-desoldering-tool-for-electronic-components-/370723601236
Why hollow, less heat loss? Will the handles stand the needles being heated directly?

Quote
I prefer plain old hss twist bits.
As opposed to what other types?


Silicone tube: Where do you get it?

Nozzle cleaners: Are these just variable-size needles?

Pin vise: Any recommend/not recommended types? Will these hold most drill bit types?

Preheater: I'm not doing it often enough to warrant getting the gear. I assume it SHOULD be possible to somehow do it without.

I'll try making a hot-needle implement; but where are all the corks when you need them...

By the way, I had a go at another board and most annoyingly I'm stuck at about the same point. 3 caps removed, 4 holes cleaned, 1 hole open but too narrow, 1 hole blocked. Like the first board, cap removal and all initial holes went mostly smooth.
 

Offline Alex Eisenhut

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Re: Cleaning up solder from a stubborn thruhole
« Reply #33 on: November 16, 2014, 04:51:48 pm »
sigh

http://www.ebay.com/itm/21pc-Mini-Micro-Drill-Bits-Set-Index-61-80-w-Blue-Aluminum-Drill-Handle-CHIDB003-/371180845759?pt=LH_DefaultDomain_0&hash=item566c1a3abf

Just drill it out. The amount of time and energy you have invested so far you could have drilled for oil by now!

I almost feel like making a video now, and I've never done that before!
*Except AC/DC adapters on eBay. Avoid them all!
 

Offline dfmischler

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Re: Cleaning up solder from a stubborn thruhole
« Reply #34 on: November 16, 2014, 04:54:51 pm »
I also have a Hakko FX-888D.  I like the 3.2mm chisel tip for recapping because it moves a lot more heat than the 1.6mm chisel tip that comes with the iron.

As for the suggestion to drill out the hole: that will work for getting the new cap into the hole, but what makes you think he will be able to melt the solder all the way through once it is in place?
 

Offline pickle9000

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Re: Cleaning up solder from a stubborn thruhole
« Reply #35 on: November 16, 2014, 05:05:14 pm »
@ lpc32

Stainless Needles:

No reason for the hollow tips as far as I know. The linked pins in the post are fairly crappy in terms of finish but they work just fine. Basically the procedure is to apply fresh solder and while it is still smoking (resin still present) poke a needle through. Use the smallest one you can get away with otherwise the solder will harden. Holding the needle on the tip will help. Remember heat will destroy the throughole plating and PCB itself if applied too long. If you can't do it in under 3-4 seconds then there is potential for damage.

Drill bits

Many bits are actually router bits they tend to wander when hand drilling. The tin or tin/lead solder is very soft so twist bits will pull a nice curl from the hole. Any hss twist bit is my pick and will stay on center.

Any pin vise will work I have a few. My preference is for one like this (narrow body):

http://www.ebay.ca/itm/Double-End-Pin-Vise-Tong-For-Jewelry-Craft-Hobby-Tools-/310602618746?pt=LH_DefaultDomain_2&hash=item48515bd77a

Pin vises and small drill bits can normally be found at a local hobby shop that sells electric train sets.


- Your picture shows a slight bowl on the bottom side this is a perfect place hand drill. The drill will autocenter on this point.   
 

Offline pickle9000

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Re: Cleaning up solder from a stubborn thruhole
« Reply #36 on: November 16, 2014, 05:23:43 pm »
I also have a Hakko FX-888D.  I like the 3.2mm chisel tip for recapping because it moves a lot more heat than the 1.6mm chisel tip that comes with the iron.

As for the suggestion to drill out the hole: that will work for getting the new cap into the hole, but what makes you think he will be able to melt the solder all the way through once it is in place?

I have done it this way many times over the years. The main issue with solder removal is that the device being used to remove or poke through the solder will have a heatsink effect and solidify the solder. This holds true for solder suckers as well. I'm talking about the marginal heating ability of any system, in some cases this can be your soldering iron / system. It could also be a simply massive ground plane on an 8 layer board with a large FET or other device on it. I have used a grinder to remove components, and the sucked out the pins after, saving a large expensive pcb can be worth it. 

For myself I often opt for drilling when I feel the end user has any chance of seeing the rework. Drilling preserves the "look" of the board. 

When it comes to time spent. I would normally solder suck holes and then just drill the one or two that need it. I could use a preheater, pins and such (I have them) but drilling is very time efficient when doing just one or two holes.
 

Offline Alex Eisenhut

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Re: Cleaning up solder from a stubborn thruhole
« Reply #37 on: November 16, 2014, 05:25:15 pm »
I also have a Hakko FX-888D.  I like the 3.2mm chisel tip for recapping because it moves a lot more heat than the 1.6mm chisel tip that comes with the iron.

As for the suggestion to drill out the hole: that will work for getting the new cap into the hole, but what makes you think he will be able to melt the solder all the way through once it is in place?

It doesn't have to melt all the way through unless he's going for an IPC certified and inspected repair. And in any case you can use two irons to bring the heat to a stubborn joint. It's far easier than using two irons and braid or whatever to unsolder.

And if he can't melt the solder, then insisting on trying to clean the hole with heat will do far more damage than a simple drill.

I mean we're at how many soldering or desoldering irons, different tips, braid, flux, stainless steel needles, or pins now?

And the holes are still plugged.

Just drill them out. It's done in 5 seconds. No heat. No flux. No needles, pins, chisel tips, braid, or mechanical engineering treatises.
*Except AC/DC adapters on eBay. Avoid them all!
 

Offline lpc32

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Re: Cleaning up solder from a stubborn thruhole
« Reply #38 on: November 16, 2014, 05:49:15 pm »
Just drill it out. The amount of time and energy you have invested so far you could have drilled for oil by now!
These eBay drills are 2 to 8 weeks away. Assuming it is possible to clean the hole with "normal" methods, isn't that an overall safer or cleaner choice?

Quote
I almost feel like making a video now, and I've never done that before!
That could be interesting. But difficult to shoot. I haven't found videos that go into detail on trouble holes, just generic "use sucker/wick" where everything works.

Many bits are actually router bits they tend to wander when hand drilling. ... Any hss twist bit is my pick and will stay on center.
How do you tell them apart?

Anyway, I've tried heating up a needle. No go. It helped to increase the hole size of an open but too narrow hole (another PCB), but not open a blocked one. Hopefully the widened hole is not damaged.



« Last Edit: November 16, 2014, 05:55:50 pm by lpc32 »
 

Offline Alex Eisenhut

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Re: Cleaning up solder from a stubborn thruhole
« Reply #39 on: November 16, 2014, 06:08:22 pm »
Just drill it out. The amount of time and energy you have invested so far you could have drilled for oil by now!

These eBay drills are 2 to 8 weeks away. Assuming it is possible to clean "normally", isn't that an overall safer or cleaner method?

How many weeks away is a new Hakko 707? (That's the one I have, it's old but it's a beast.)

Quote
I almost feel like making a video now, and I've never done that before!
There could be interesting. But difficult to shoot.

Anyway, I've tried heating up a needle. No go. It helped to increase the hole size of an open but too narrow hole (another PCB), but not open a block one. Hopefully the widened hole is not damaged.

Fair enough. I didn't want to have to do it, but here goes:

Get a BIC pen. Take out the innards and the endcap. Now you have a nice blowgun. Heat the joint with fresh solder and make sure you have a nice plug of as hot as possible solder going. While you are still heating the joint, move the iron away from the hole but still on the copper, now bring the BIC pen to the hole and blow as hard as you can. Of course do this as one quick move. And needless to say: don't inhale!

The best way is to have a board holder, heat the joint from beneath, and look at top of the joint, when it's liquid you blow it out! The advantage is that the iron only needs to heat the joint and not any additional stuff like braid or a pin.

Of course there's the danger of a hot slug of solder flying all over the place, but there you go.

And if the other side of the joint looks like a dying T-1000, that's far easier to fix now that the solder is out of the hole.
*Except AC/DC adapters on eBay. Avoid them all!
 

Offline pickle9000

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Re: Cleaning up solder from a stubborn thruhole
« Reply #40 on: November 16, 2014, 06:17:00 pm »
For ID here are a couple images.

Regular twist drills are easy to spot, same diameter all the way along. You should be able to get these from a local hobby shop.

Items with the fat shank are the ones to stay away from. It is possible to find bits of the correct type in this format it's just easier to get the other ones.
 

Offline Alex Eisenhut

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Re: Cleaning up solder from a stubborn thruhole
« Reply #41 on: November 16, 2014, 06:32:11 pm »
For ID here are a couple images.

Regular twist drills are easy to spot, same diameter all the way along. You should be able to get these from a local hobby shop.

Items with the fat shank are the ones to stay away from. It is possible to find bits of the correct type in this format it's just easier to get the other ones.

That's not a routing bit, it's a carbide twist drill for drilling PCBs. It's far too brittle for routing or hand-drilling.

http://en.wikipedia.org/wiki/Drill_bit#PCB_through-hole_drill_bits
*Except AC/DC adapters on eBay. Avoid them all!
 

Offline pickle9000

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Re: Cleaning up solder from a stubborn thruhole
« Reply #42 on: November 16, 2014, 06:37:09 pm »
For ID here are a couple images.

Regular twist drills are easy to spot, same diameter all the way along. You should be able to get these from a local hobby shop.

Items with the fat shank are the ones to stay away from. It is possible to find bits of the correct type in this format it's just easier to get the other ones.

That's not a routing bit, it's a carbide twist drill for drilling PCBs. It's far too brittle for routing or hand-drilling.

http://en.wikipedia.org/wiki/Drill_bit#PCB_through-hole_drill_bits

I know, it's an example shape of what to avoid.
 

Offline lpc32

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Re: Cleaning up solder from a stubborn thruhole
« Reply #43 on: November 17, 2014, 04:53:37 pm »
heat the joint from beneath, and look at top of the joint, when it's liquid you blow it out!
But this too needs the same basic requirement: having the whole joint liquid.

As for the suggestion to drill out the hole: that will work for getting the new cap into the hole, but what makes you think he will be able to melt the solder all the way through once it is in place?
A good question. I'm assuming part of the problem is the old (leadfree?) solder, or something mechanical blocking heat transfer, but I don't know. The only trivial thing I can think of next is to try drilling.

Though, I'm unhappy about not being able to clean it up normally, or even know for sure why it doesn't work.

With only an iron, manual sucker, and wick, how common do you get holes that need drilling? In the two boards I have here it's 2 (or 3 with the narrow hole) out of 12, not a good ratio.
 

Offline AG6QR

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Re: Cleaning up solder from a stubborn thruhole
« Reply #44 on: November 17, 2014, 05:28:40 pm »
With only an iron, manual sucker, and wick, how common do you get holes that need drilling? In the two boards I have here it's 2 (or 3 with the narrow hole) out of 12, not a good ratio.

About 80% of the holes I try come clean the first time using only an iron and wick (sometimes with flux added).  Every one of the remaining ones has come clean using a little piece of resistor lead, and heating the hole and lead with an iron while pushing the lead through the hole.  That technique was mentioned in the second reply on this thread. 

I've never tried any of the other techniques mentioned on this thread, not because I think there's something wrong with them, but because wick and a resistor lead have always worked.  I can't count the number of holes I've cleaned up that way, but it's a lot.
 

Offline Smith

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Re: Cleaning up solder from a stubborn thruhole
« Reply #45 on: November 17, 2014, 06:10:59 pm »
Most will do fine when adding some new solder.
I occasionally use a heat plate aka second hand 500W kitchen warming plate when the ground plane is just to large. Heating the board to 100/125 degrees does wonders.
Trying is the first step towards failure
 

Offline dfmischler

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Re: Cleaning up solder from a stubborn thruhole
« Reply #46 on: November 18, 2014, 11:45:08 am »
With only an iron, manual sucker, and wick, how common do you get holes that need drilling? In the two boards I have here it's 2 (or 3 with the narrow hole) out of 12, not a good ratio.

I have never had a hole that I had to drill because I couldn't heat it up enough to suck it out, but I use a much larger tip on my iron, and I have a Weller iron, heat gun and hot air station that I could use as well.  I even have a 100 watt soldering gun that I could use if really necessary, but I can't ever remember using it on a PC board.

Hints: leaded solder (e.g. 63/37) melts at a lower temperature than unleaded.  Adding leaded solder to the joint can help by reducing the melting temperature.  Unless you have really top-of-the-line equipment a bigger tip generally moves more heat.
 

Offline nanofrog

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Re: Cleaning up solder from a stubborn thruhole
« Reply #47 on: November 18, 2014, 07:17:16 pm »
I occasionally use a heat plate aka second hand 500W kitchen warming plate when the ground plane is just to large. Heating the board to 100/125 degrees does wonders.
+1  :-+

Adding more heat via an electric skillet has been mentioned in another thread the OP started. Not sure if he's ignoring it or missed it.  :-// Even a hair dryer could help (trying to think of something that may be on-hand or purchased locally to finish the job same day).
 

Online nali

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Re: Cleaning up solder from a stubborn thruhole
« Reply #48 on: November 18, 2014, 08:07:37 pm »
I've used before one of those 500W yard floodlights that you can buy in DIY superstores for £5 or so to preheat boards.. which has the advantage of not needing direct contact for heat transfer. Warning: Use a dimmer or make sure you switch it off when the board gets to temperature or you'll get lots of smoke & molten solder!  :palm:
 

Offline tiago

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Re: Cleaning up solder from a stubborn thruhole
« Reply #49 on: November 18, 2014, 09:06:09 pm »
Heat the pad and whack the board against the table.

Crude but effective.
 


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