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Old 10-24-2019, 03:56 AM   #1
dicky96
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Default clearing solder from very small vias

Hi guys
I'm trying to fix this satellite receiver. it has an expensive subscription on it that I can't transfer to another box

Basically the owner has broken the HDMI connector

I have another reciever of the same type that is blocked (so I can't put a subscription on it)

I've successfully desoldered the HDMI connector from that one. The connector came out just fine. However I can't clear the solder from all the small holes. I'm practicing on the blocked box, but will then have to do this on the active one to replace the HDMI connector

I've tried a few techniques that I know but I'm getting nowhere fast

I've tried wicking out with flux and solder braid and managed to clear a couple of holes but it isn't very successful

I've tried a manual solder sucker but it doesn't work

I have some stainless steel needles but even the smallest guage in the set is too thick to go through these holes

I've tried tinning the holes with 60/40 and then tapping firmly on my bench but it doesn't work

I consider myself pretty good at micro soldering but I suspect I am missing the correct technique in my arsenal of soldering knowledge

Rich
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Old 10-24-2019, 04:09 AM   #2
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Default Re: clearing solder from very small vias

have you tried drilling them through ?
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Old 10-24-2019, 04:18 AM   #3
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Default Re: clearing solder from very small vias

I add lots of 60/40 hopefully getting it mixed with the lead free, remove as much as I can with Chemtronics braid, more flux and my iron and then hot air from above with the solder sucker underneath to clear any remaining holes.
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Old 10-24-2019, 05:53 AM   #4
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Default Re: clearing solder from very small vias

You need a decent through hole solder extraction system to deal effectively with this, I use a Pace SX-80 or SX-90 for rework such as this. Should there be a problems with very large thermal masses then hot air from one side and solder extraction system on the other

If this is not an option then remove as much solder as you can and carefully drill out the remaining material or find some one local to you whom can do this for you.
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Old 10-24-2019, 07:22 AM   #5
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Default Re: clearing solder from very small vias

pre-heat the area with hot air,
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Old 10-24-2019, 09:49 AM   #6
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Default Re: clearing solder from very small vias

Would heating with hot air or soldering iron until solder is molten, then using a compressed air duster can to blow the solder out, do the job?
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Old 10-24-2019, 11:46 AM   #7
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Default Re: clearing solder from very small vias

no idea, it may just cool the board.
i did wonder once if melting the solder with a vac cleaner hose on the other side would work, but never tried it.
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Old 10-24-2019, 11:55 AM   #8
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Default Re: clearing solder from very small vias

There's one way to find out then.......
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Old 10-24-2019, 01:20 PM   #9
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Default Re: clearing solder from very small vias

Use good solder braid with solder wick inside it, or add lots of wick to it.
Cover the holes with lead-solder.
Use the biggest tip you have (more thermal mass) and try the braid again.
P.S: If the soldering iron does not measure the temp inside the tip just set it to the highest temperature.
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Old 10-25-2019, 02:57 AM   #10
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Default Re: clearing solder from very small vias

Quote:
Originally Posted by dicky96 View Post
I've tried a few techniques that I know but I'm getting nowhere fast

I've tried tinning the holes with 60/40 and then tapping firmly on my bench but it doesn't work
Usually works for me, but ain't fast... repeat 3 to 4 times per hole.

imo, neither compressed air duster or vac cleaner hose will work because the solder will cool even faster
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Old 10-25-2019, 06:12 AM   #11
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Default Re: clearing solder from very small vias

In the end I did it (on the faulty PCB) but with a couple of lifted pads.

Mostly I used the addition of some more 60:40 plus heating the area with my heatgun then solder wick dipped in rosin and my soldering iron.

That went OK but there were 5 problematic holes that I eventually managed to clear by using the legs of a small resistor that were narrow enough to pass through the holes

So due to the repeated heating and clearing that's where a couple of the pads got damaged

It was very time consuming and not a total success in the end so I wouldn't like to do this the same way on the good PCB.

I would really like to buy the Pace MBT250 + SX100 but it's expensive and I've been investing a lot of money into the business recently and I have to stop somewhere. Shame because I used the origianal Pace desoldering tools back in the 80s and they were really excellent.

Would something like this do the job? It's 90W so that sounds reasonably useful.
https://www.aliexpress.com/item/3290...chweb201603_55

Also I could get one of these to preheat the board from below and that should help. These are cheap too
https://www.aliexpress.com/item/3301...chweb201603_55



I much prefer the wand type desoldering tools but this is affordable and I'm not doing this type of work every day. Most of it is smd.

best regards
Rich

Last edited by dicky96; 10-25-2019 at 06:17 AM..
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Old 10-25-2019, 06:13 AM   #12
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Default Re: clearing solder from very small vias

Try sharpened wood toothpick or some 0.5 0.3mm Pencil Lead Refills if fits.
Hot air station and or hot air gun (with some nozzle) to blow away solder
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Old 10-25-2019, 11:26 AM   #13
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Default Re: clearing solder from very small vias

Hmm I'm leaning towards getting one of those solder sucker guns I posted in #11 and one of the Kada preheaters as well

They seem to have some good reviews on Aliexpress. Has anyone here used that one (or equivalent)?
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Old 10-25-2019, 02:36 PM   #14
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Default Re: clearing solder from very small vias

the desoldering station is made by zhong-di, and sold under many names.
they are pretty good - i have a similar one.
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Old 10-25-2019, 04:01 PM   #15
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Default Re: clearing solder from very small vias

Quote:
the desoldering station is made by zhong-di, and sold under many names.
they are pretty good - i have a similar one.
I have a few of them as well they work fairly well

I do have have a recommendation for you and that this

Buy extra tips and filters for the Desoldiering station when you buy it you will need them
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Old 10-26-2019, 06:22 AM   #16
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Default Re: clearing solder from very small vias

Thanks guys
I've ordered the SS-331H vacuum desoldering stations and one of the Kada 853B Hot air preheaters as well

Hopefully these will be a useful addition to the workshop. I'll know in about 3 weeks when they come from China
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Old 10-26-2019, 06:37 AM   #17
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Default Re: clearing solder from very small vias

I've also added a couple of these to my order

https://www.aliexpress.com/item/3255...chweb201603_55

They look like they would be useful, and so cheap too.
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Old 10-26-2019, 04:21 PM   #18
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Default Re: clearing solder from very small vias

i also recomend an inline filter to protect the pump,
i linked a banggood one in an older thread.
like this:
https://www.banggood.com/Universal-P...-p-993094.html
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Old 10-26-2019, 04:25 PM   #19
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Default Re: clearing solder from very small vias

Thank stj that looks like a good idea. and so cheap they practically give them away

Bit like living here large beer..... 1.50 euro

Last edited by dicky96; 10-26-2019 at 04:29 PM..
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Old 11-18-2019, 10:03 PM   #20
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Default Re: clearing solder from very small vias

Is there a reason you dont just heat the board up with a hot air gun until the solder liquefies and then push the connector through the holes? You can put fresh solder on all the pins after.

Those little pins love to come off when you try and desolder them . I would use a micro hand drill before I tried desoldering them but I would just heat the board and put the connector on first.
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