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New Heat-Reduced Magnetic Solder Could Revolutionize Chip Design
A new heat-reduced soldering technique using magnets may lead to some revolutionary changes in the way chips are manufactured. Details are scant since the inventor seems to be playing it close to the vest for now in hopes of attracting chipmaker interest. "The result is a tin-silver alloy that contains a dispersion of iron particles tens of micrometers in diameter. When a magnetic field is applied to the solders, two things happen. First, the iron particles heat up, locally melting the solder. This localized heating, which works on the same principle as inductive stoves, remains completely contained, keeping the surrounding area cool. And second, the iron particles line up with the direction of the magnetic field, squeezing and pushing the liquid in that direction. This alignment is retained when the solder solidifies, and the well-ordered particles provide mechanical reinforcement that's greater than that afforded by a regular dispersion of particles."
How much iron are we talking about? Is this tantamount to having ferrite beads on all connections now?
-jcr
The only title of honor that a tyrant can grant is "Enemy of the State."
Will Microsoft install a magnetic field generator in the next Xbox to ensure the solder fails there, too?
Kwisatz Haderach
Sell the spice to CHOAM
This Mahdi took Shaddam's Throne
From the article:
A new type of solder can be melted and shaped in three dimensions under the force of a weak magnetic field
How weak are we talking about here? I wouldn't want my chips to become desoldered just because they were exposed to an electromagnetic field. The article didn't mention any thing about that.
The result is a tin-silver alloy that contains a dispersion of iron particles tens of micrometers in diameter.
Not saying it can't work, as the above is light on precise chemistry, but in an alloy like this, you're bound to have atoms floating around... say, to the surface of the deposition... where it will oxidize. And something like OSP (which yes, wouldn't bond to SnAg) only lasts so long in storage... Don't we already have ENOUGH problems with solder joint oxidation? I look forward to seeing how this issue is addressed.
If I had a nickel for every time I had a nickel, I'd be richcursive!
Not to be pedantic, but this is the Internet... They are applying magnetic flux to their solder, not just a magnetic field. A field doesn't impart any energy.
A slashdotter who didn't build his own computer is like a Jedi who didn't build his own lightsaber.
This would work great for individual components, and you could leave final assembly in the realm of other soldering techniques.
The only problem with that is that when you want to use two separate bonding techniques on a board, the cost and complexity skyrockets. This is why (or at least, one reason) this is traditionally avoided (the exception for that is reflow and wave soldering, which touch different component types... DIP vs. surface mount... even then though, the chemistries involved are frequently similar).
Even if you could manufacture that on the cheap, how are you going to support it? Throw away whole boards instead of rework/repair them? Some boards might be cheap enough to just throw away... but if they're that cheap, you're probably not using a fancy pants soldering technique anyhow.
If I had a nickel for every time I had a nickel, I'd be richcursive!
JB Weld contains so much iron particulate in suspension that it responds to a magnetic field. If it weren't for the fact that the particles are so much larger and get drawn out of suspension and toward the magnet, it might be possible to speed-cure the stuff with this same trick.
Once the solder melts, it should be possible to shape it using a refrigerator magnet -- molten solder simply doesn't have much viscosity or structural strength. You don't need to worry, though: melting it is done by inductive heating, which requires a strong time-varying magnetic field.
"They redundantly repeated themselves over and over again incessantly without end ad infinitum" -- ibid.
Solder is already conductive, so the eddy current losses won't be localized in the iron particles. Further, copper traces are even more conductive.
This must be based on the hysteresis losses in the iron B-H curves. That means he's probably got a very high frequency magnetic field generator that he's using to heat up the iron. Seems like a simple principle.
That said, I still don't want iron filings in my solder!
In soldering 101 I learned that if you put hot solder on cold metal, the solder doesn't really wet the joint, and you will get early or immediate failure of conductivity. You can even accidentally create a diode. So why will this work?
"When a magnetic field is applied to the solders, two things happen. First, the iron particles heat up, locally melting the solder. This localized heating, which works on the same principle as inductive stoves, remains completely contained, keeping the surrounding area cool."
Quote from ScuttleMonkey, the Slashdot editor: "Details are scant..."
Neither the Slashdot editor or the writer of the linked article understand the physics. Magnetic fields cause something to heat only if the field is rapidly changing. Then the magnetic field causes everything conductive to heat, including iron particles.
When you bring a magnet near a PC, the damage is done to magnetic recording media, not the chips. Silicon is not generally sensitive to magnetic fields. This guy has managed to put a video game controllers, keyboards, and mice inside an MRI bore. If those integrated circuits can work in a 3T magnetic field, I'm pretty sure it can survive this new magnetic assembly technique.
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