EEVblog #437 - Removing SMD Parts with ChipQuick

[robbak]

The Canonical thread seems to be missing, so I'll put one in. Feel Free to remove it to put the right one in.

The Video: http://youtu.be/UmD7F0--7Lc

I wanted to add to this thread, with the following:

The users over at YouTube consider this a variant of Field's Metal, or perhaps Cerrosafe with some indium. Low melting point metals are really interesting. Cast a teaspoon out of one of them, and hand it to an unsuspecting guest!

Secondly, used ChipQuick would have some extra solder contamination, but it should still be useable. But using it as a ball would be difficult, so how would you go about getting it back into wire or strips for reuse?

[LoyalServant]

I have used this stuff for many years and it works a treat.
Dave used too much of it and he lifted a passive when he did the second flat pack 

You really only need a small amount of this stuff for it to work.
I use it in conjunction with a hot air gun and it works better for me that way.
You also reduce the risk of lifting pads and bending pins if you want to reuse the chip.

Good product I highly recommend it.

[Kiwi_frog]

I also have used this for years, I prefer it to hot air.  It's crucial that the pcb is cleaned properly after.

The flux is some of the best I've used for re-flow also...

Mike.

[justanothercanuck]

I laughed when I saw the patent sticker pasted on the packet of alcohol wipes.  I see boxes of those wipes at work on a weekly basis.

[notsob]

The main ingredient in chipquik is bismuth (approx50%), similar product to zephtronics 'lowmelt' product.

[G7PSK]

There is a whole host of low melting point alloys, at one time you could buy spoons made from such metals which would melt when stirring your tea or coffee. The link is to wikipedia woods metal which then gives a list of other alloys which I have also put below.

http://en.wikipedia.org/wiki/Wood's_metal

Alloy   Melting point   Eutectic?   Bismuth   Lead   Tin   Indium   Cadmium   Thallium
Rose's metal   98 °C (208 °F)   no   50%   25%   25%   –   –   –
Cerrosafe   74 °C (165 °F)   no   42.5%   37.7%   11.3%   –   8.5%   –
Wood's metal   70 °C (158 °F)   yes   50%   26.7%   13.3%   –   10%   –
Field's metal   62 °C (144 °F)   yes   32.5%   –   16.5%   51%   –   –
Cerrolow 136   58 °C (136 °F)   yes   49%   18%   12%   21%   –   –
Cerrolow 117   47.2 °C (117 °F)   yes   44.7%   22.6%   8.3%   19.1%   5.3%   –
Bi-Pb-Sn-Cd-In-Tl   41.5 °C (107 °F)   yes   40.3%   22.2%   10.7%   17.7%   8.1%   1.1%

[ktulu]

If you don't have a hot air gun, it is still possible to salvage IC's (or any parts) from a PCB by heating it from underneath with a lighter or torch, or even your regular gas cooking plate. 
The board will be demaged of course, and you need good ventilation.

[Winston]

With its 58C melting point, it looks like Bolton 136 (Cerro Low 136) is it:

http://shop.boltonmetalproducts.com/Bolton-136-formerly-sold-as-Cerro-Low-136-LB220002.htm

"Alloy is used in anchoring parts for machining (jet blades); testing, inspection, block lenses in optical manufacturing, proof casting; fusible element in safety devices (sprinkler heads); fusible cores in compound cores; low temperature solder; sealing adjustment screws and many craft applications."

$100.43/lb

[robrenz]

Idealy you want to anticipate the addition of the tin and lead from the solder you are blending with. So you would want the Cerro Low 136 alloy with the tin and lead removed.  Then when you add it to the solder you end up with aproximately the Cerro Low 136 alloy with a 58C melting point.

[free_electron]

This is a high bismuth alloy. Even though bismuth itself only melts at 270 degree c it lowers the melting point of other metals drastically.

The reason this stuff works is because of two things:
You put on quite bit of mass. That mass , combined with the heat retention capability of the qfp and the board you are heating up ( remeber you need to heat the whole thing ) gives you a long tome where the alloy remains in liquiod state.

Always remeber to thoroughly clean the pads of this stuff ! You don't want to contaminate you solder withe bit of bismuth.

[EExtrom]

Didnt know this stuff exist ... quite expensive though ... anyway, THANKS!

[kodai]

Its just plain old woods metal.  Those of use that play with crystal radios know it very well as its been a part of crystal sets for about a hundred years now.  When you place down your gelana crystal for your cats whisker you put it in a little metal cup that is filled with woods metal.  You can use hot water to melt it and you prevent damage to the crystal by using low heat.  Lots of beginners try to solder their crystal in place but find out the hard way that it kills the crystal.  So woods metal is the only real way to get a full connection to the crystal.  I've often wondered if solder and woods metal would mix and what the outcome would be.  Now I know.  Now I also know of a good source to get some more for my radio builds when my limited supply of woods metal runs out (got about 3-4 more uses left), so thanks for the vid.  ^_^

[KuchateK]

Dave, it probably took you so long to remove that big chip because although you melted ChipQuick on the pins soldering iron temperature was too low for existing solder underneath.

[Arp]

I bought a few packs of 70% medical iso-propanol pads some time ago. They contained skin lotion to prevent drying of the skin. Left a nasty residue on the mirror. I thought this lotion was common with medical pads?

[justanothercanuck]

I bought a few packs of 70% medical iso-propanol pads some time ago. They contained skin lotion to prevent drying of the skin. Left a nasty residue on the mirror. I thought this lotion was common with medical pads?

I don't think I've come across any of the lotion ones at work, people actually bring in their own moisturizers because of the alcohol...  It used to be worse before they changed the hand wash stations... they also were a high-percent alcohol, and it would make your hands all chapped.  The wipes shown in the video are just 70% isopropyl.

[m0r]

Seeing the nice blobs of alloy it forms, have any of you tried to be cheap and reused this kind of material?

[shashwatratan]

Cool Stuff! Never Used it.




Shashwat

[LaurenceW]

OOPS! Watch for C08  just to the south of the small chip which is desoldered as part of the second demonstration. 

Now ya see it, then ya don't...

[JoannaK]

Nice video. I used this in 2000 or so when I needed to replace qfp-chip (SMC ethernet) on one of our boards. Back then the hot air gun's were not as easy to find as these days (china clones) so this ChipQuick was really a treat.

Expensive, yes. But on a day you need it, it's totally worth the money.

[divelectservices]

Good stuff...worth every penny when you have a "must-salvage" board or chip.  Very messy to clean up though, too thin for the desoldering station to suck up.  Solder wick and a nylon brush work good on the board and hot air works on the chip.

[tom66]

Someone suggested this was regular solder mixed with bismuth.

I found some bismuth to confirm, but unfortunately, it did not work when trying to solder with it (not entirely unexpected.) I'm guessing it needs to be "melted in" with the solder then re-drawn out into a wire. And I'd guess the concentration is important. But I'm not a metallurgist.

So for now I'll use plenty of flux, wick and hot air... and I have no problem. May not be as fast though, but I'm rarely in a rush.

[Excavatoree]

OOPS! Watch for C08  just to the south of the small chip which is desoldered as part of the second demonstration. 

Now ya see it, then ya don't...

You can still see it.  (for a bit) It ended up in the large blob on the right.  Dave cut to a shot after he removed the blob and the poor, lost C8.

Seriously, it has to be a result of the strange soldering iron angle needed to work under the camera.

[EEVblog]

Seriously, it has to be a result of the strange soldering iron angle needed to work under the camera.

Yes, the angles are limited when you have an inverted tripod hanging overhead, and not wanting to move the board to keep the shot consistent etc.
It's a lot different to when I'd just ordinarily do it.

Dave.

[amyk]

Someone suggested this was regular solder mixed with bismuth.

I found some bismuth to confirm, but unfortunately, it did not work when trying to solder with it (not entirely unexpected.) I'm guessing it needs to be "melted in" with the solder then re-drawn out into a wire. And I'd guess the concentration is important. But I'm not a metallurgist.

So for now I'll use plenty of flux, wick and hot air... and I have no problem. May not be as fast though, but I'm rarely in a rush.

According to the MSDS it's Sn 12% Pb 18% Bi 49% In 21%

[Moshly]

I've used this stuff a bit at work and home. Just a few points to add.

You can reuse it, it works fine for around 6 - 8 uses.
More if you add more fresh ChipQuick & always use lots of flux.

Works best on small to medium size gull wing & all J lead parts.

You need to use a washing / squelching type motion to mix the alloy & the solder.
Just putting it on top of the joins is insufficient as it needs to mix.
Use a circular motion as you add solder, that causes the solder to pulse in & out between the pins a few times.

You still need to bring the part and the PCB up to soldering like temperatures before you remove the part, its just that when you do, you have around 10 seconds or more to remove the part.